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KAIST presents a fundamental technology to remove metastatic traits from lung cancer cells
KAIST (President Kwang Hyung Lee) announced on January 30th that a research team led by Professor Kwang-Hyun Cho from the Department of Bio and Brain Engineering succeeded in using systems biology research to change the properties of carcinogenic cells in the lungs and eliminate both drug resistance and their ability to proliferate out to other areas of the body.
As the incidences of cancer increase within aging populations, cancer has become the most lethal disease threatening healthy life. Fatality rates are especially high when early detection does not happen in time and metastasis has occurred in various organs. In order to resolve this problem, a series of attempts were made to remove or lower the ability of cancer cells to spread, but they resulted in cancer cells in the intermediate state becoming more unstable and even more malignant, which created serious treatment challenges.
Professor Kwang-Hyun Cho's research team simulated various cancer cell states in the Epithelial-to-Mesenchymal Transition (EMT) of lung cancer cells, between epithelial cells without metastatic ability and mesenchymal cells with metastatic ability. A mathematical model of molecular network was established, and key regulators that could reverse the state of invasive and drug resistant mesenchymal cells back to the epithelial state were discovered through computer simulation analysis and molecular cell experiments. In particular, this process succeeded in properly reverting the mesenchymal lung cancer cells to a state where they were sensitive to chemotherapy treatment while avoiding the unstable EMT hybrid cell state in the middle process, which had remained a difficult problem.
The results of this research, in which KAIST Ph.D. student Namhee Kim, Dr. Chae Young Hwang, Researcher Taeyoung Kim, and Ph.D. student Hyunjin Kim participated, were published as an online paper in the international journal “Cancer Research” published by the American Association for Cancer Research (AACR) on January 30th. (Paper title: A cell fate reprogramming strategy reverses epithelial-to-mesenchymal transition of lung cancer cells while avoiding hybrid states)
Cells in an EMT hybrid state, which are caused by incomplete transitions during the EMT process in cancer cells, have the characteristics of both epithelial cells and mesenchymal cells, and are known to have high drug resistance and metastatic potential by acquiring high stem cell capacity. In particular, EMT is further enhanced through factors such as transforming growth factor-beta (TGF-β) secreted from the tumor microenvironment (TME) and, as a result, various cell states with high plasticity appear. Due to the complexity of EMT, it has been very difficult to completely reverse the transitional process of the mesenchymal cancer cells to an epithelial cell state in which metastatic ability and drug resistance are eliminated while avoiding the EMT hybrid cell state with high metastatic ability and drug resistance.
Professor Kwang-Hyun Cho's research team established a mathematical model of the gene regulation network that governs the complex process of EMT, and then applied large-scale computer simulation analysis and complex system network control technology to identify and verify 'p53', 'SMAD4', and 'ERK1' and 'ERK 2' (collectively ERKs) through molecular cell experiments as the three key molecular targets that can transform lung cancer cells in the mesenchymal cell state, reversed back to an epithelial cell state that no longer demonstrates the ability to metastasize, while avoiding the EMT hybrid cell state.
In particular, by analyzing the molecular regulatory mechanism of the complex EMT process at the system level, the key pathways were identified that were linked to the positive feedback that plays an important role in completely returning cancer cells to an epithelial cell state in which metastatic ability and drug resistance are removed.
This discovery is significant in that it proved that mesenchymal cells can be reverted to the state of epithelial cells under conditions where TGF-β stimulation are present, like they are in the actual environment where cancer tissue forms in the human body.
Abnormal EMT in cancer cells leads to various malignant traits such as the migration and invasion of cancer cells, changes in responsiveness to chemotherapy treatment, enhanced stem cell function, and the dissemination of cancer. In particular, the acquisition of the metastatic ability of cancer cells is a key determinant factor for the prognosis of cancer patients. The EMT reversal technology in lung cancer cells developed in this research is a new anti-cancer treatment strategy that reprograms cancer cells to eliminate their high plasticity and metastatic potential and increase their responsiveness to chemotherapy.
Professor Kwang-Hyun Cho said, "By succeeding in reversing the state of lung cancer cells that acquired high metastatic traits and resistance to drugs and reverting them to a treatable epithelial cell state with renewed sensitivity to chemotherapy, the research findings propose a new strategy for treatments that can improve the prognosis of cancer patients.”
Professor Kwang-Hyun Cho's research team was the first to present the principle of reversal treatment to revert cancer cells to normal cells, following through with the announcement of the results of their study that reverted colon cancer cells to normal colon cells in January of 2020, and also presenting successful re-programming research where the most malignant basal type breast cancer cells turned into less-malignant luminal type breast cancer cells that were treatable with hormonal therapies in January of 2022. This latest research result is the third in the development of reversal technology where lung cancer cells that had acquired metastatic traits returned to a state in which their metastatic ability was removed and drug sensitivity was enhanced.
This research was carried out with support from the Ministry of Science and ICT and the National Research Foundation of Korea's Basic Research in Science & Engineering Program for Mid-Career Researchers.
< Figure 1. Construction of the mathematical model of the regulatory network to represent the EMT phenotype based on the interaction between various molecules related to EMT.
(A) Professor Kwang-Hyun Cho's research team investigated numerous literatures and databases related to complex EMT, and based on comparative analysis of cell line data showing epithelial and mesenchymal cell conditions, they extracted key signaling pathways related to EMT and built a mathematical model of regulatory network (B) By comparing the results of computer simulation analysis and the molecular cell experiments, it was verified how well the constructed mathematical model simulated the actual cellular phenomena. >
< Figure 2. Understanding of various EMT phenotypes through large-scale computer simulation analysis and complex system network control technology.
(A) Through computer simulation analysis and experiments, Professor Kwang-Hyun Cho's research team found that complete control of EMT is impossible with single-molecule control alone. In particular, through comparison of the relative stability of attractors, it was revealed that the cell state exhibiting EMT hybrid characteristics has unstable properties. (B), (C) Based on these results, Prof. Cho’s team identified two feedbacks (positive feedback consisting of Snail-miR-34 and ZEB1-miR-200) that play an important role in avoiding the EMT hybrid state that appeared in the TGF-β-ON state. It was found through computer simulation analysis that the two feedbacks restore relatively high stability when the excavated p53 and SMAD4 are regulated. In addition, molecular cell experiments demonstrated that the expression levels of E-cad and ZEB1, which are representative phenotypic markers of EMT, changed similarly to the expression profile in the epithelial cell state, despite the TGF-β-ON state. >
< Figure 3. Complex molecular network analysis and discovery of reprogramming molecular targets for intact elimination of EMT hybrid features.
(A) Controlling the expression of p53 and SMAD4 in lung cancer cell lines was expected to overcome drug resistance, but contrary to expectations, chemotherapy responsiveness was not restored. (B) Professor Kwang-Hyun Cho's research team additionally analyzed computer simulations, genome data, and experimental results and found that high expression levels of TWIST1 and EPCAM were related to drug resistance. (C) Prof. Cho’s team identified three key molecular targets: p53, SMAD4 and ERK1 & ERK2. (D), (E) Furthermore, they identified a key pathway that plays an important role in completely reversing into epithelial cells while avoiding EMT hybrid characteristics, and confirmed through network analysis and attractor analysis that high stability of the key pathway was restored when the proposed molecular target was controlled. >
< Figure 4. Verification through experiments with lung cancer cell lines.
When p53 was activated and SMAD4 and ERK1/2 were inhibited in lung cancer cell lines, (A), (B) E-cad protein expression increased and ZEB1 protein expression decreased, and (C) mesenchymal cell status including TWIST1 and EPCAM and gene expression of markers related to stem cell potential characteristics were completely inhibited. In addition, (D) it was confirmed that resistance to chemotherapy treatment was also overcome as the cell state was reversed by the regulated target. >
< Figure 5. A schematic representation of the research results.
Prof. Cho’s research team identified key molecular regulatory pathways to avoid high plasticity formed by abnormal EMT of cancer cells and reverse it to an epithelial cell state through systems biology research. From this analysis, a reprogramming molecular target that can reverse the state of mesenchymal cells with acquired invasiveness and drug resistance to the state of epithelial cells with restored drug responsiveness was discovered.
For lung cancer cells, when a drug that enhances the expression of p53, one of the molecular targets discovered, and inhibits the expression of SMAD4 and ERK1 & ERK2 is administered, the molecular network of genes in the state of mesenchymal cells is modified, eventually eliminating metastatic ability and it is reprogrammed to turn into epithelial cells without the resistance to chemotherapy treatments. >
2023.01.30 View 11833 -
NYC-KAIST Cooperation Agreement Signed in New York for KAIST NYU Joint Campus
A ceremony was held to celebrate the signing of the Cooperative Agreement between NYC and KAIST and the presentation of the signage for KAIST NYU Joint Campus at NYU’s Kimmel Center in Manhattan.
KAIST President Kwang Hyung Lee (left) and NYU President Andrew Hamilton (right)
KAIST (President Kwang Hyung Lee) signed a cooperative agreement with the City of New York and had an official showing of the signage for the Joint Campus of KAIST and New York University (NYU) on September 21 at 4:00 pm (Eastern Standard Time) at NYU’s Kimmel Center in New York City with the NYC Mayor Eric Adams, the Korean Minister of Science and ICT Dr. Lee Jong-ho, NYU Chairman William Berkley, NYU President Andrew Hamilton, and other distinguished guests in attendance.
KAIST and NYU signed a Memorandum of Understanding in June about building a joint campus in an effort to educate global talent. As a follow-up measure, NYU has provided KAIST with space to begin joint research programs and held a ceremony to present the signage designed for the future KAIST NYU Campus. In line with these efforts, KAIST has also signed an agreement with New York City, the administrative authority in charge of the establishment of the campus, for mutual cooperation.
NYU is a prestigious university headquartered in Manhattan, New York. It has nurtured outstanding talents in the humanities, art, and basic sciences, including 38 Nobel Prize winners, 5 Fields Prize winners, 26 Pulitzer Prize winners, and 38 Academy Award winners to be deserving of the evaluation.
The proposed joint campus is to be centered on science, technology, engineering, and mathematics (STEM) by combining NYU's excellent basic sciences and convergence research capabilities with KAIST's globally renowned science and technology capabilities. The joint initiative is expected to launch in 2023; its programs will focus on areas such as AI Basic Science, AI Convergence Brain Science, AI-Applied Cyber Security, Cyber Security, and Sustainable High-Tech Smart City/Climate Change in order to lead the Digital Era and to solve the problems that surfaced following the COVID-19 pandemic. In addition, in order to prepare for the Post-AI Era, it was decided to create the “New Engineering” program for undergraduate program that employs a hyper-convergence learning model that combines project-based, problem-solving learning (PBL, PSL) pedagogy.
▲ Biomedical Engineering- Research and development of technology to respond to the entire cycle (prevention-treatment-diagnosis-prediction) for a new infectious disease (Disease X) by converging new technologies such as IT and NT with biomedical technologies
▲ AI Convergence Neuroscience- Research on brain-machine interaction and brain-based machine learning through AI technology convergence
▲ AI Science- Algorithm development and in-depth research in preparation for the post AI era
▲ Sustainability and Climate Change- R&DB for advanced smart cities, sustainability for the global environment and carbon zero
▲ Next-generation Wireless Communications- From ICT to AIT: Research on 6G/7G related technologies, new communications theories, and etc.
▲ Cyber Security- Advanced research on protection of digital information and information safety/reliability
KAIST President Kwang Hyung Lee (left) and NYC Mayor Eric Adams (right)
The KAIST NYU Joint Campus has started enlisting professors and researchers from both institutions to participate in the collaboration. The campus will also function as the headquarter that will oversee the operation of the joint research program. At Daejeon, KAIST is also setting up a location for NYU on its main campus to provide space for NYU researchers upon their visit to KAIST.
The KAIST NYU Joint Campus, which has begun to take basic shape with the space for collaboration rendered this time, is to be upgraded to “KAIST New York Campus” in the future to function also as an industry-academic cooperation campus in which that promotes strategic cooperation with industries and expands start-up opportunities. To this end, the related procedures from the detailing of the establishment plans through a preliminary feasibility studies, to deliberation and decision on whether to proceed with the establishment by the KAIST Board of Trustees, will be taken.
The KAIST NYU Campus is expected to serve as a stepping stone for the outstanding talents of KAIST to pursue their dreams in the global market and research environment while seizing the attention of the world-class talents drawn to New York at the same time. In addition, by combining NYU's strong basic academic capabilities with KAIST’s strengths, it is expected to contribute to achieving 'global innovation' by creating synergies in various fields such as education, research, and entrepreneurship. The future KAIST-NYU Campus is also expected to encompass an industry-academic cooperation campus with industrial partners and startups.
Meanwhile, KAIST is planning to expand its excellent scientific and technological capabilities to the global stage through the cooperative agreement with New York City, and to prepare a pathway for KAIST students, faculty, and startups to enter their respective fields in the global markets. In the future, KAIST plans to explore areas of cooperation in different fields, such as education, economy, society, and culture, to prepare and implement detailed cooperation plans.
< KAIST-New York City Cooperation Items (Example) >
▲ Education: Joint degree program with a university in New York City, training of key talents in the field of artificial intelligence, etc.
▲ Economy: A hub for technology startups, job creation in the tech sector, etc.
▲ Society: Economics, finance, media-related engineering research, etc.
▲ Culture: Diversity-based culture and art-tech research, etc.▲ Etc: Joint research in the field of artificial intelligence healthcare, etc.
As a global mecca for startups, education, and investment, New York has a well-developed global network for cultural diversity and successful career development, and has great power to attract various resources including funds and talented individuals. Based on this, it has established itself as a mecca of global tech companies and global top media groups, and is building the reputation as 'Silicon Alley' in addition to its legends of the ‘Wall Street'.
Dr. Andrew Hamilton, the president of NYU, said, “We’re delighted by our newly established partnership with KAIST. We see great potential in the opportunities to collaborate on development of courses, research, cutting edge technologies, university-level courses, degrees, entrepreneurship initiatives and industrial partnerships, and exchanges. We believe this partnership is very much in line with NYU’s commitment to global engagement and will make important contributions to New York’s tech sector. It’s exciting to think how much NYU and KAIST have much to learn from one another, and how much we may accomplish together.”
New York City Mayor Eric Adams said, “We’re proud to have helped facilitate this partnership between KAIST and New York University, which will be a real win for students and help drive continued innovation in our city.” He added, “From the time that senior members of our administration learned about this opportunity during a recent trip to South Korea, we have worked closely with KAIST to develop strategies for increasing their presence and investments in New York. This is the start of a relationship that I am confident will bring even more academic, business, and technological opportunities to the five boroughs.”
Dr. Kwang Hyung Lee, the president of KAIST, urged, “Based on the KAIST-NYU partnership, we must create an interdisciplinary hyper-convergence model of collaboration and use cutting-edge tools to create an innovative model for new type of problem-solving engineering education to prepare to solve the challenges facing the world.” He went on to stress, “The new fusion engineering degree program will leverage the unique strengths of the two institutions to provide a uniquely colored education not found anywhere else.” In addition, he added, “KAIST will utilize the advantages that are unique to the global city of New York to contribute to advancing the science and technology research in New York City and creating jobs in the tech sector to lead the renaissance of Silicon Alley.”
2022.09.27 View 10495 -
Big Ideas on Emerging Materials Explored at EMS
Renowned scholars and editors from academic journals joined the Emerging Materials e-Symposium (EMS) held at KAIST and shared the latest breakthroughs and big ideas in new material development last month. This e-symposium was organized by Professor Il-Doo Kim from the KAIST Department of Materials Sciences and Engineering over five days from September 21 through 25 via Zoom and YouTube. Professor Kim also serves as an associate editor of ACS Nano.
Esteemed scholars and editors of academic journals including ACS Nano, Nano Energy, and Energy Storage Materials made Zoom presentations in three main categories: 1) nanostructures for next-generation applications, 2) chemistry and biotechnology for applications in the fields of environment and industry, and 3) material innovation for technological applications.
During Session I, speakers including Professor John A. Rogers of Northwestern University and Professor Zhenan Bao of Stanford University led the session on Emerging Soft Electronics and 3D printing.
In later sessions, other globally recognized scholars gave talks titled Advanced Nanostructuring for Emerging Materials, Frontiers in Emerging Materials Research, Advanced Energy Materials and Functional Nanomaterials, and Latest Advances in Nanomaterials Research.
These included 2010 Nobel Prize laureate and professor at Manchester University Andre Geim, editor-in-chief of ACS Nano and professor at UCLA Paul S. Weiss, Professor Paul Alivisatos of UC Berkeley, Professor William Chueh of Stanford University, and Professor Mircea Dinca of MIT.
KAIST President Sung-Chul Shin, who is also a materials physicist, said in his opening address, “Innovation in materials science will become an important driving force to change our way of life. All the breakthroughs in materials have extended a new paradigm that has transformed our lives.”
“Creative research projects alongside global collaborators like all of you will allow the breakthroughs that will deliver us from these crises,” he added.
(END)
2020.10.06 View 12318 -
Expanding Gas Storage Capacity of Nanoporous Materials
A KAIST research team led by Professor Jihan Kim of the Department of Chemical and Biomolecular Engineering has successfully proposed a rational defect engineering methodology that can greatly enhance the gas storage capacity of nanoporous materials. The team conducted a high-throughput computational screening of a large experimental metal-organic framework database to identify 13 candidate materials that could experience significant methane uptake enhancement with only a small proportion of linker vacancy defects.
This research was published online on November 16 in Nature Communications, with M.S. candidate Sanggyu Chong from KAIST as the first author and post-doctorate researcher Günther Thiele from the Department of Chemistry at UC Berkeley as a contributing author.
Metal-organic frameworks, hereinafter MOF, are crystalline nanoporous materials that are comprised of metal clusters and organic linkers continuously bound together by coordination bonds. Due to their ultrahigh surface areas and pore volumes, they have been widely studied for various energy and environment applications.
Similar to other crystalline materials, MOFs are never perfectly crystalline and are likely to contain several different types of defects within their crystalline structures. Among these defects, linker vacancy defects, or the random absence of linker vacancies in their designated bonding positions, are known to be controllable by practicing careful control over the synthesis conditions.
The research team combined the concepts of rational defect engineering over the linker vacancy defects and the potential presence of inaccessible pores within MOFs to propose a methodology where controlled the introduction of linker vacancy defects could lead to a dramatic enhancement in gas adsorption and storage capacities.
The study utilized a Graphic Processing Unit (GPU) code developed by Professor Kim in a high-throughput computational screening of 12,000 experimentally synthesized MOFs to identify the structures with significant amounts of pores that were inaccessible for methane. In determining the presence of inaccessible pores, a flood-fill algorithm was performed over the energy-low regions of the structure, which is the same algorithm used for filling an area with color in Microsoft Paint.
For the MOFs with significant amounts of inaccessible pores, as determined from the screening, the research team emulated linker vacancy defects in their crystalline structures so that the previously inaccessible pores would be newly merged into the main adsorption channel with the introduction of defects for additional surface area and pore volume available for adsorption. The research team successfully identified 13 structures that would experience up to a 55.56% increase in their methane uptake with less than 8.33% of the linker vacancy defects.
The research team believes that this rational defect engineering scheme can be further utilized for many other applications in areas such as selective adsorption of an adsorbate from a gas mixture and the semi-permanent capture of gas molecules.
This research was conducted with the support of the Mid-career Research Program of the National Research Foundation of Korea.
Figure1. A diagram for flood fill algorithm and example of identification of inaccessible regions within the MOFs, using the flood fill algorithm
Figure2. Methane energy contours before and after detect introduction
2017.12.04 View 7165 -
Dr. Zi Jing Wong Named 2017 Jeong Hun Cho Awardee
(Photo caption: The 2017 Jeong Hun Cho Scholarship recipients pose with President Shin (left photo) and Dr. Zi Jing Wong, the recipient of the 2017 Jeong Hun Cho Award)
Dr. Zi Jing Wong, a postdoctoral scholar at the University of California, Berkeley was named the 2017 recipient of the Jeong Hun Cho Award. The award recognizes outstanding young scientists in the field of aerospace engineering annually. The recipient receives a 20 million KRW prize.
The Award Committee said that Dr. Wong who earned his MS at KAIST Department of Aerospace Engineering is a rising scholar in the fields of optic meta materials, photonics, imaging, among others. He has published five papers on the realization of a zero refractive index and the control of a refractive index, as well as the realization of a 3D invisibility cloak in Science and Nature Photonics in 2014 and 2015. Dr. Wong also swept the best paper awards from many international academic societies including the US Materials Research Society, IEEE, SPIE, and Metamaterials Congress in 2015. He finished his Ph.D. at the University of California, Berkeley.
The Award Committee also named three recipients of the Jeong Hun Cho Scholarship: Ph.D. candidate Hyon-Tak Kim of the Department of Aerospace Engineering at KAIST, Ph.D. candidate Ho-Song Park from the Department of Mechanical Engineering at Korea University, and Hyong-Jin Choi of Kongju National University High School.
The award was endowed by the family of the late Ph.D. candidate Jeong Hun Cho who died in a rocket lab accident in the Department of Aerospace Engineering in 2003. Cho was posthumously conferred an honorary doctorate degree.
In memory of Cho, his father established the ‘Jeong Hun Cho Award and Scholarship.’ The scholarship annually selects three young scholars from Cho’s alma maters of KAIST, Korea University, and Kongju National University High School.
2017.05.12 View 9848 -
A mechanism for how reactive oxygen species cause cell responses studied
A research team led by Professor Kwang-Hyun Cho of the Department of Biology and Brain Engineering, KAIST, and Dr. Gi-Sun Kwon of the Korea Research Institute of Bioscience and Biotechnology succeeded in proving the mechanism behind the determination of cell life in relation to reactive oxygen species.
The results of the venture were published in the June 3rd edition of Science Signaling. The title of the research paper is “MLK3 is part of a feedback mechanism that regulates different cellular responses to reactive oxygen species.”
The research team discovered that the molecular switch that determines the division of apoptosis of a cell was based on MLK3 feedback mechanism. MLK stands for mixed-lineage kinase.
Under sufficient stress, the mechanism instructs the cell to undergo the division but in an overly stressful environment, the mechanism stops the cell division and instead, induces apoptosis. This discovery is expected to be a breakthrough in illnesses related to the concentration of the reactive oxygen species (ROS).
At low concentration of ROS, the protein associated with cell division, ERK (extracellular-signal-regulated kinase), is activated while as the ROS concentration increases, JNK (c-Jun N-terminal protein kinases), responsible for apoptosis, becomes activated. Furthermore, through computer simulation analysis and mathematical modeling, in tandem with molecular cell biology experiments, the MLK3 based feedback mechanism was the fundamental molecular switch that determines the balance between ERK and JNK, and ultimately the cell’s responses.
Professor Cho commented that “the contradicting cell responses to ROS had remained a mystery, but with the system biology, an approach in which information technology and biotechnology converge, such riddles can be resolved. We expect that the proven mechanism will be used to overcome aging or cancer growth as a result of ROS in the near future.”
Picture shows the process of identifying cell responses caused by reactive oxygen species.
2014.06.13 View 8795 -
Leon Chua, the founder of the circuit theory called "memristor," gave a talk at KAIST
Dr. Leon Ong Chua is a circuit theorist and professor in the Department of Electrical Engineering and Computer Sciences at the University of California, Berkeley. He visited KAIST on April 16, 2014 and gave a talk entitled “Memristor: New Device with Intelligence.”
Dr. Chua contributed to the development of nonlinear circuit theory and cellular neural networks (CNN). He was also the first to conceive of memristor which combines the characteristics of memory and resistor. Memristor is a type of resistor, remembering the direction and charge of electrical current that has previously flowed through the resistor. In other words, memristor can retain memory without power. Today, memristor is regarded as the fourth fundamental circuit element, together with capacitors, inductors, and resistors.
In 2008, researchers at Hewlett-Packard (HP) Labs developed the first working model of memristor, which was reported in Nature (May 1st , 2008).
In addition, Dr. Chua is an IEEE fellow and has received numerous awards including the IEEE Kirchhoff Award, the IEEE Neural Network Pioneer Award, the IEEE Third Millennium Medal, and the Top 15 Most Cited Author in Engineering Award.
2014.04.21 View 9298 -
"Modeling and Simulation of Discrete Event Systems" by Professor Byoung-Kyu Choi, Selected as Textbook by UC Berkeley
The book, "Modeling and Simulation of Discrete Event Systems," written by Professor Byoung-Kyu Choi from the Department of Industrial and Systems Engineering at KAIST, was selected as a textbook for the Department of Industrial Engineering at the University of California in Berkeley (UC Berkeley).It was published based on professor Choi’s lecture notes and has been used as a textbook for both undergraduate and graduate students at KAIST.Professor Lee W. Schruben from the Department of Industrial Engineering at UC Berkeley said, “It was selected as a textbook for the discrete event simulation course since it shows outstanding educational methodology as well as academic values.”Professor Choi said, “This is the first case of an American university choosing a Korean industrial engineering publication as a textbook. We should be proud of the high evaluation of KAIST’s Industrial and Systems Engineering Department.” The School of Engineering in UC Berkeley was ranked third in the Times Higher Education World University Rankings in 2013.
2014.01.29 View 7670 -
Professor Young-Ho Cho elected as head of international academic conference
KAIST’s Professor Young-Ho Cho of the Department of Bio and Brain Engineering was appointed as the head of the PowerMems (Power Micro Electro Mechanical Systems) symposium to be held at Se-Jong Hotel in Seoul from November 15-18, 2011.
Professor Jo is America’s first engineering doctor in the field of MEMS and is the founding member of the BSAC (Berkeley Sensor and Actuator Center), the start of the MEMS technology.
PowerMEMS is the core of green growth and next generation energy production. It focuses on harvesting energy from minute vibrations or renewable energy sources such as sunlight or plants to harvest and store energy via micro or even nano size systems.
The symposium was first held in 2000, and it is where leading experts in the field share papers on the production and harvesting energy in the micro scale.
2011.01.14 View 10389 -
Nanowerk Spotlight: Bacteria as environmentally friendly nanoparticle factories, Sep. 24, 2010
The Nanowerk.com is a leading portal site for nanotechnology and nanosciences, which runs a daily news section called “Spotlight.” On September 24, 2010, the Spotlight published an article on the latest developments of the research by a KAIST team headed by Distinguished Professor Sang-Yup Lee of the Chemical and Bimolecular Engineering Department. For the article, please click the link below:
Nanowerk Spotlight: Bacteria as environmentally friendly nanoparticle factories, Sep. 24, 2010
By Michael Berger.
http://www.nanowerk.com/spotlight/spotid=18188.php
2010.09.25 View 10009 -
Photonic crystals allow the fabrication of miniaturized spectrometers
By Courtesy of Nanowerk
Photonic crystals allow the fabrication of miniaturized spectrometers
(Nanowerk Spotlight) Spectrometers are used in materials analysis by measuring the absorption of light by a surface or chemical substance. These instruments measure properties of light over a specific portion of the electromagnetic spectrum. In conventional spectrometers, a diffraction grating splits the light source into several beams with different propagation directions according to the wavelength of the light. Thus, to achieve sufficient spatial separation for intensity measurements at a small slit, a long light path – i.e., a large instrument – is required.
However, for lab-on-a-chip or microTAS (total analysis system) applications, the spectrometer must be integrated into a sub-centimeter scale device to produce a stand-alone platform. To achieve this, researchers at the Korea Advanced Institute of Science and Technology (KAIST) propose a new paradigm in which the spectrometer is based on an array of photonic crystals with different bandgaps.
"Because photonic crystals refelct light of different wavelengths selectively depending on their bandgaps, we can generate reflected light spanning the entire wavelength range for analysis at different spatial positions using patterned photonic crystals," Seung-Man Yang, Director of the National Creative Research Initiative Center for Intergrated Optofluidic Systems and Professor of the Department of Chemical & Biomolecular Engineering at KAIST, tells Nanowerk. "Therefore, when the light source impinges on the patterned photonic crytals, we can construct the spectrum using the reflection intensity profile from the constituent photonic crystals."
Photonic crystals – also known as photonic band gap material – are similar to semiconductors, only that the electrons are replaced by photons (i.e. light). By creating periodic structures out of materials with contrast in their dielectric constants, it becomes possible to guide the flow of light through the photonic crystals in a way similar to how electrons are directed through doped regions of semiconductors. The photonic band gap (that forbids propagation of a certain frequency range of light) gives rise to distinct optical phenomena and enables one to control light with amazing facility and produce effects that are impossible with conventional optics.
To demonstrate this new concept based on patterned photonic crystals, Yang and his group used non-close-packed colloidal crystals of silica particles dispersed in photocurable resin. Due to the repulsive interparticle potential, monodisperse silica particles spontaneously crystallize into non-close-packed face-centered cubic (fcc) structures at volume fractions above 0.1. Therefore, the particle volume fraction determines both the lattice constant and the bandgap position.
a) Optical image of an ETPTA film containing porous photonic crystal stripe patterns with 20 different bandgaps. b) Reflectance spectra from the 20 strips. c) Optical microscope image of the middle region with the parallel stripe pattern (denoted as white-dotted box in a). d) Cross-sectional SEM images of first, sixth, eleventh and seventeenth strips. The scale bars in a, c and d are 1 cm, 2mm and 2 µm, respectively. (reprinted with permission from Wiley-VCH Verlag)
Reporting their findings in a recent issue of Advanced Materials ("Integration of Colloidal Photonic Crystals toward Miniaturized Spectrometers"), the KAIST team has demonstrated the integration of colloidal photonic crystals with 20 different bandgaps into freestanding films (prepared by soft lithography), and their application as a spectrometer.
Yang explains that the team was able to precisely control the photonic bandgap by varying the particle size and volume fration.
"The prepared colloidal composite structures showed high physical rigidity and chemical resistivity" he says. "The composite structure is suitable for spectroscopic use due to the small full widths at half maximum (FWHMs) of the reflectance spectra, which mean that there is little overlap of the reflectance spectra of neighboring photonic crystal strips."
"On the other hand" says Yang, "porous photonic crystals showed large FWHMs and high reflectivities, which should prove useful in many practical photonic applications that require high optical performance and physical rigidity as well as simple and inexpensive preparation."
In addition to fabricating miniaturized spectrometers, which can for instance be integrated into small lab-on-a-chip devices, these integrated photonic crystals can be potentially used for tunable band reflection mirrors, optical switches, and tunable lasing cavities. Moreover, patterned photonic crystals with RGB colors are well-suited for use in reflection-mode microdisplay devices.
Yang points out that, although the spectrometric resolution can be reduced by employing the smaller bandgap interval and photonic bandwidth, there is a limitation. "Now, we are studying photonic crystals with continuous modulation of bandgap position. We expect that the photonic crystals can reduce the resolution to 0.01 nm."
By Michael Berger. Copyright 2010 Nanowerk
2010.03.17 View 13089
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KAIST Team Identifies Nano-scale Origin of Toughness in Rare Earth-added Silicon Carbide
A research team led by Prof. Do-Kyung Kim of the Department of Materials Science and Engineering of KAIST has identified the nano-scale origin of the toughness in rare-earth doped silicon carbide (RE-SiC), university sources said on Monday (Oct. 6).
The research was conducted jointly with a U.S. team headed by Prof. R. O. Ritchie of the Department of Materials Science and Engineering, University of California, Berkeley.
The findings were carried in the online edition of Nano Letters published by the American Chemical Association.
Silicon carbide, a ceramic material known to be one of the hardest substances, are potential candidate materials for many ultrahigh-temperature structural applications. For example, if SiC, instead of metallic alloys, is used in gas-turbine engines for power generation and aerospace applications, operating temperatures of many hundred degrees higher can be obtained with a consequent dramatic increase in thermodynamic efficiency and reduced fuel consumption. However, the use of such ceramic materials has so far been severely limited since the origin of the toughness in RE-SiC remained unknown thus far.
In order to investigate the origin of the toughness in RE-SiC, the researchers attempted to examine the mechanistic nature of the cracking events, which they found to occur precisely along the interface between SiC grains and the nano-scale grain-boundary phase, by using ultrahigh-resolution transmission electron microscopy and atomic-scale spectroscopy. The research found that for optimal toughness, the relative elastic modulus across the grain-boundary phase and the interfacial fracture toughness are the most critical material parameters; both can be altered with appropriate choice of rare-earth elements.
In addition to identifying the nano-scale origin of the toughness in RE-SiC, the findings also contributed to precisely predicting how the use of various rare-earth elements lead to difference in toughness.
University sources said that the findings will significantly advance the date when RE-SiC will replace metallic alloys in gas-turbine engines for power generation and aerospace applications.
2008.10.08 View 13933