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Extremely Thin and Highly Flexible Graphene-Based Thermoacoustic Speakers
A joint research team led by Professors Jung-Woo Choi and Byung Jin Cho of the School of Electrical Engineering and Professor Sang Ouk Kim of the Material Science and Engineering Department, all on the faculty of the Korea Advanced Institute of Science and Technology (KAIST), has developed a simpler way to mass-produce ultra-thin graphene thermosacoustic speakers.
Their research results were published online on August 17, 2016 in a journal called Applied Materials & Interfaces. The IEEE Spectrum, a monthly magazine published by the Institute of Electrical and Electronics Engineers, reported on the research on September 9, 2016, in an article titled, “Graphene Enables Flat Speakers for Mobile Audio Systems.” The American Chemical Society also drew attention to the team’s work in its article dated September 7, 2016, “Bringing Graphene Speakers to the Mobile Market.”
Thermoacoustic speakers generate sound waves from temperature fluctuations by rapidly heating and cooling conducting materials. Unlike conventional voice-coil speakers, thermoacoustic speakers do not rely on vibrations to produce sound, and thus do not need bulky acoustic boxes to keep complicated mechanical parts for sound production. They also generate good quality sound in all directions, enabling them to be placed on any surface including curved ones without canceling out sounds generated from opposite sides.
Based on a two-step, template-free fabrication method that involved freeze-drying a solution of graphene oxide flakes and the reduction/doping of oxidized graphene to improve electrical properties, the research team produced a N-doped, three-dimensional (3D), reduced graphene oxide aerogel (N-rGOA) with a porous macroscopic structure that permitted easy modulation for many potential applications.
Using 3D graphene aerogels, the team succeeded in fabricating an array of loudspeakers that were able to withstand over 40 W input power and that showed excellent sound pressure level (SPL), comparable to those of previously reported 2D and 3D graphene loudspeakers.
Choong Sun Kim, the lead author of the research paper and a doctoral student in the School of Electrical Engineering at KAIST, said:
“Thermoacoustic speakers have a higher efficiency when conducting materials have a smaller heat capacity. Nanomaterials such as graphene are an ideal candidate for conductors, but they require a substrate to support their extremely thinness. The substrate’s tendency to lose heat lowers the speakers’ efficiency. Here, we developed 3D graphene aerogels without a substrate by using a simple two-step process. With graphene aerogels, we have fabricated an array of loudspeakers that demonstrated stable performance. This is a practical technology that will enable mass-production of thermosacoustic speakers including on mobile platforms.”
The research paper is entitled “Application of N-Doped Three-Dimensional Reduced Graphene Oxide Aerogel to Thin Film Loudspeaker.” (DOI: 10.1021/acsami.6b03618)
Figure 1: A Thermoacoustic Loudspeaker Consisted of an Array of 16 3D Graphene Aerogels
Figure 2: Two-step Fabrication Process of 3D Reduced Graphene Oxide Aerogel Using Freeze-Drying and Reduction/Doping
Figure 3: X-ray Photoelectron Spectroscopy Graph of the 3D Reduced Graphene Oxide Aerogel and Its Scanning Electron Microscope Image
2016.10.05 View 11882 -
Special Lecture by Professor Sung-Hou Kim of UC Berkeley
As part of its special lecture series, the Department of Biological Sciences at KAIST has invited Professor Sung-Hou Kim of the Department of Chemistry at the University of California, Berkeley, to lecture on his research in structural biology. He will speak twice on May 23 and 30, respectively, on the topics “Origin of Universe and Earth—A Narrative” and “Origin of Life and Human Species—A Narrative.”
Professor Kim's research addresses the structural basis of molecules to reveal how they communicate with each other to activate or inhibit particular processes in cell growth, cell differentiation, and cancer. Using the single-crystal X-ray diffraction technology, he discovered, for the first time in the world, the three-dimensional (3-D) structure of a transfer RNA (t-RNA) and received much praise for this work from the scientific community. Since then, he has been cited as a candidate for a Nobel Prize in Chemistry for many years.
He also examined the 3-D structures of a RAS protein in normal and cancer cells and identified the mutations of the RAS protein as a cause for cancer. His work has assisted in the development of target drugs for cancer treatment. In recent years, he has adopted a computational biology approach to study the structure and function of biological genomics, with which he has tried to predict disease-sensitive genes.
Professor Kim graduated from Seoul National University in 1962 and received his Ph.D. degree in chemistry from the University of Pittsburgh in the United States in 1966. He worked at the Massachusetts Institute of Technology (MIT) as a senior research scientist, and has taught at UC Berkeley since 1978.
2016.05.23 View 6184 -
Symposium on Creative Education
KAIST and the Korea Society for Creativity and Application (KSCA) co-hosted a symposium on creative education on January 21, 2016 at the KAIST Business and Management College in Seoul. Along with the symposium, the two organizations also held the Korea "Theory of Inventive Problem Solving" (TRIZ) Festival 2016.
Around 200 experts from academia, industry, and research including Dong-Suk Kim, Dean of the KAIST College of Business and Management and Gui-Chan Park, Director of POSCO Group Academy, attended the symposium.
The event was organized to celebrate the foundation of KSCA and to increase social awareness of creative education and design-related thinking with a "TRIZ approach."
"TRIZ" stands for the “Theory of Inventive Problem Solving” in Russian. It is a problem-solving method based on logic and data, not intuition, which accelerates the project team’s ability to work out issues creatively. The "TRIZ approach" has been widely used among Korean companies including Samsung, LG, and POSCO as a means of boosting employees’ creativity.
The academic symposium was divided into a keynote speech, paper presentations from each field, and a poster fair.
Professor Dae-Sik Kim from KAIST delivered a keynote speech on “Neuroscience and Creativity,” offering a glimpse of the world from a neuroscience perspective. Jae-min Lee, a researcher at Samsung Electronics, provided an industrial case study, “Application of TRIZ for the Improvement of Refrigerator.” Professor Jung-Seok Hyun from Jeju University and Dr. Jung-Ho Shin from E-Triz System presented their application of TRIZ on “Limitless Imagination and Invention Class for the Elementary School Students.” Altogether, 36 other research papers and case studies were presented at the symposium.
Dr. Dong-ryul Yang, President of KSCA, said, “This academic symposium allows us to discuss a range of innovative case studies that utilize TRIZ in industrial and educational fields, from which we can learn good lessons and practices.”
2016.01.19 View 5716 -
Professor Keon-Jae Lee Lectures at IEDM and ISSCC Forums
Professor Keon-Jae Lee of KAIST’s Materials Science and Engineering Department delivered a speech at the 2015 Institute of Electrical and Electronics Engineers (IEEE) International Electron Devices Meeting (IEDM) held on December 7-9, 2015 in Washington, D.C.
He will also present a speech at the 2016 International Solid-State Circuits Conference scheduled on January 31-February 4, 2016 in San Francisco, California.
Both professional gatherings are considered the world’s most renowned forums in electronic devices and semiconductor technology. It is rare for a Korean researcher to be invited to speak at these global conferences.
Professor Lee was recognized for his research on flexible NAND chips. The Korea Times, an English language daily newspaper in Korea, reported on his participation in the forums and his recent work. An excerpt of the article follows below:
“KAIST Professor to Lecture at Renowned Tech Forums”
By Lee Min-hyung, The Korea Times, November 26, 2015
Recently he has focused on delivering technologies for producing flexible materials that can be applied to everyday life. The flexible NAND flash memory chips are expected to be widely used for developing flexible handsets. His latest research also includes flexible light-emitting diodes (LED) for implantable biomedical applications.
Lee is currently running a special laboratory focused on developing new flexible nano-materials. The research group is working to develop what it calls “self-powered flexible electronic systems” using nanomaterials and electronic technology.
Lee’s achievement with flexible NAND chips was published in the October edition of Nano Letters, the renowned U.S.-based scientific journal.
He said that flexible memory chips will be used to develop wearable computers that can be installed anywhere.
2015.11.26 View 9418 -
KAIST Develops New Technique for Chiral Activity in Molecules
Professor Hyunwoo Kim of the Chemistry Department and his research team have developed a technique that can easily analyze the optical activity of charged compounds by using nuclear magnetic resonance (NMR) spectroscopy. The research finding entitled “H NMR Chiral Analysis of Charged Molecules via Ion Pairing with Aluminum Complexes” was published online in the October 19th issue of The Journal of the American Chemical Society.
The technique relies on observation of the behavior of optical isomers. Molecules with the same composition that are mirror images of each other are optical isomers. For example, the building blocks of all living organisms, amino acids, are a single optical isomer. In our bodies, optical isomers bring different physiological changes due to their distinct optical activities. Therefore, controlling and analyzing the optical activities are critical when developing a new drug.
High-performance liquid chromatography (HPLC) is the de facto standard of analyzing the optical activity of a compound. However, HPLC is very expensive that many laboratories can’t afford to have. In addition, with the machine, one analysis may take 30 minutes to one hour to complete. It lacks in signal sensitivity and chemical decomposition, and the application is limited to nonpolar compounds.
Usually adopted in analyzing the structure of a chemical compound, NMR spectroscopy requires only one to five minutes per single analysis. Since it is essential for analyzing the molecular structure, many chemistry labs have NMR equipment. However, until this technique was invented, no other research team had reported an effective way of using the NMR spectroscopy to decompose the signal of chiral activity of a compound.
The research team uses negatively-charged metal compounds in NMR spectroscopy. The technique employs negatively-charged metal compounds which bond ionically to positively- and negatively-charged optical compounds. As a result, the NMR spectroscopy can distinguish the signal from chiral activity. Not only can it analyze various chemicals without structural constraints, but it can also be used for both nonpolar and polar solvents.
As many compounds for new drugs have functional groups, which can be charged, this analysis method can be directly employed in the development process of drugs. Professor Kim said, “A revolutionary analysis method has been developed using simple chemical principles. I hope that our method will be applied to the development of new medicine.”
This research was sponsored by the Center for Nanomaterials and Chemical Reactions at the Institute for Basic Science and the Supercomputing Research Center of KAIST.
Picture 1: Separations of NMR Signals of Chemicals due to Interaction with Metal Compounds
Picture 2: Separations of NMR Signals in Different Chemicals
2015.11.20 View 10889 -
Open KAIST 2015
KAIST’s research environment and its most recent achievements were open to the public.
KAIST hosted “Open KAIST 2015” over two days from November 5-6, 2015 in which its 17 departments and three research centers were open to the public. The event is one of the largest events that KAIST holds, which permits such public viewings of its facilities. It is the eighth time it has taken place.
During this event, the departments and centers offered 64 programs including laboratory tours, research achievement exhibitions, department introductions, and special lectures.
The “Motion Capture System”of Professor Jun-Yong Noh’s lab (Graduate School of Culture Technology) drew particular attention.
The “Motion Capture System” expresses human and animal motion in three-dimensional (3D) space using infrared cameras and optic markers, which can then be applied to various industries such as movies, games, and animation. During the program, researchers themselves demonstrated the recording of the movement and its conversion into 3D characters.
Professor Yong-Hoon Cho’s laboratory introduced the scientific mechanism behind the Light Emitting Diode (LED) as well as its manufacturing process under the topic:“A to Z of LED Production.” The reserachers explained that how green LED is much more efficient compared to previous light sources and presented applications that how it is widely used in everyday life in smart phones, electronic displays, and other mobile gadgets.
Professor Jun-tani of the Department of Electronic and Electrical Engineering introduced “Humanoid Robot Nao’s Imitation of Human Motions.” Nao is an autonomous, programmable humanoid robot developed by a French robotics company based in Paris. Nao has an artificial neural circuit, which is the functional equivalent of a human brain, and can thus mimic the subject’s motions through learning.
In addition, Professor Hyo-Choong Bang (Department of Aerospace Engineering) in his lecture on “Unmanned Vehicle Research and Nano Satellites” and Professor Hyun Myung (Department of Civil and Environmental Engineering) on his lecture on “Future Civilization Robot System: the Jellyfish Elimination Robotic Swarm and the Wall-Climbing Drone” provided information on the progress of their respective research.
KAIST also displayed its most recent research achievements. A lecture on “Information Technology Convergence” offered a showroom for “Dr. M,” which is a mobile healthcare platform. Dr. M is a mobile healthcare system that collects and analyzes biosignals via a smart sensor attached to the human body that shows around 20 advanced technologies.
The Satellite Technology Research Center introduced the public to its “Get to Know Satellites” program on Korea’s first satellite “Our Star 1” in addition to showing the satellite assembly room and the satellite communication center.
Special lectures were also held for visitors. Professor Min-Hyuk Kim and Hye-Yeon Oh of the School of Computing talked about “Computer Graphics and Advanced Video Technology” and “Man and the Computer,” respectively, from the perspective of non-experts.
Another interesting feature was the “Wearable Computer Competition” in which college students held fashion shows with computers attached to their clothes.
Professor Jung Kwon Lee, the Dean of the College of Engineering, who led this event, said that “the Open KAIST, which is being held for the eighth time this year, is an excellent opportunity for the general public to experience KAIST’s research environment.” He hoped this could motivate young adults to widen their spectrum of scientific knowledge and raise affection for science.
2015.11.13 View 9363 -
President Steve Kang of KAIST Receives the Outstanding Contribution Award from the Korean-American Scientists and Engineers Association
The Korean-American Scientists and Engineers Association (KSEA), a non-profit Korean professional organization based in the United States with over 6,000 registered members, bestowed upon President Steve Kang of KAIST the 2015 Outstanding Contribution Award.
The award is presented to a person who has made significant contributions to the development of KSEA.
The award ceremony took place during the 2015 US-Korea Conference on Science, Technology, and Entrepreneurship (UKC), which was held on July 30, 2015, at the Hyatt Regency Hotel in Atlanta, Georgia.
The UKC is the flagship conference of KSEA, which takes place every year, and covers science, engineering, technology, industry, entrepreneurship, and leadership. It attracts more than 1,200 participants from the US and Korea. The UKC 2015 was held on July 29-August 1, 2015.
President Kang has participated in UKC conferences over the past few years as a plenary speaker, addressing major issues in science and technology for both nations, and provided generous support for the activities of UKC and KSEA. He also promoted discussions and exchanges of professional knowledge in his field, microelectronics, by organizing fora and symposia.
He addressed the UKC 2015 as a plenary speaker with a speech entitled “Pursuing Excellence with a Servant’s Heart.” President Kang said that good leadership should bring out synergistic contributions from all constituents and achieve excellence under all circumstances. He mentioned one example of good leadership, known as humble leadership, and explained how such leadership played an important role in the development of scientific breakthroughs, such as the world’s premier high-end microprocessor chip sets first produced by his team under extremely high pressure.
2015.08.05 View 6508 -
Professor Sung Yong Kim Presents a Keynote Speech at the International Ocean Color Science Meeting (IOCS) 2015
Professor Sung Yong Kim of the Mechanical Engineering Department at KAIST delivered a keynote speech at the International Ocean Color Science Meeting (IOCS) 2015 held in San Francisco on June 15-18, 2015. His speech was entitled “Research and Applications Using Sub-mesoscale GOCI (Geostationary Ocean Color Imager) Data.”
The IOCS, organized by the International Ocean Color Coordinating Group (IOCCG), is a community consultation meeting providing communication and collaboration between space agencies and the ocean color community, building strong ties among international representatives of the ocean color communities, and providing a forum for discussion and the evolution of community thinking on a range of issues.
Professor Kim was recognized for his contribution towards the development of remote exploration of sub-mesoscale processes including eddies, fronts, and environmental fluid dynamics.
He also attended the 26th General Assembly of the International Union of Geodesy and Geophysics (IUGG) in Prague, the Czech Republic, on June 22, 2015 and gave a presentation on the sub-mesoscale eddies circulation research.
2015.06.12 View 7976 -
Professor Shim Featured with His Drone System in IEEE Spectrum
The IEEE Spectrum, a technology and science magazine published by the Institute of Electrical and Electronics Engineers (IEEE), featured an article of KAIST’s autonomous unmanned aerial vehicles (UAVs) entitled “South Korea Prepares for Drone vs. Drone Combat,” posted on April 1, 2015.
The article introduces the anti-drone defense system being developed by Professor “David” Hyunchul Shim of the Department of Aerospace Engineering at KAIST. With the goal of developing guard drones that can detect and capture unknown UAVs, the anti-drone defense system consists of reconnaissance drones, agile multi-rotor UAVs equipped with nets which are dropped to snare enemy drones, and transport UAVs to carry smaller drones.
Professor Shim currently leads KAIST’s Unmanned System Research Group (USRG, http://unmanned.kaist.ac.kr/) and Center of Field Robotics for Innovation, Exploration, aNd Defense (C-FRIEND).
For the article, please go to http://spectrum.ieee.org/automaton/robotics/aerial-robots/south-korea-drone-vs-drone.
2015.04.02 View 11486 -
Qualcomm Innovation Award Recognizes 20 KAIST Students
The
award provides research fellowships, worth of USD 100,000, to 20 KAIST graduate
students
With an audience of 100 people present,
KAIST held a ceremony for the Qualcomm Innovation Award 2015 at the Information
Technology Convergence building on campus on March 12, 2015.
The Qualcomm Innovation Award, established
in 2010, is a fellowship that supports innovative science and engineering master’s
and doctoral students at KAIST. Qualcomm donated USD 100,000 to KAIST, stipulating that it be used to foster a creative research environment for graduate
students.
To select the recipients, KAIST formed an award committee chaired
by Professor Soo-Young Lee of the Department of Electrical Engineering and accepted research proposals until late January.
The award committee first selected 37
proposals from 75 papers submitted and then chose the final 20 research
proposals on March 12, 2015 after presentation evaluations. The presentations had to show promise of innovation and creativity; prospective influence on wireless communications
and mobile industry; and the prospect of being implemented.
Each recipient received a USD 4,500 research
fellowship along with an opportunity to present their research findings at a
workshop where Qualcomm engineers and other distinguished individuals of the industry
will attend.
Previously, Qualcomm has donated
research fellowships to KAIST graduate students in 2011 and 2013.
2015.03.19 View 9111 -
A KAIST Student Team Wins the ACM UIST 2014 Student Innovation Contest
A KAIST team consisted of students from the Departments of Industrial Design and Computer Science participated in the ACM UIST 2014 Student Innovation Contest and received 1st Prize in the category of People’s Choice.
The Association for Computing Machinery (ACM) Symposium on User Interface Software and Technology (UIST) is an international forum to promote innovations in human-computer interfaces, which takes place annually and is sponsored by ACM Special Interest Groups on Computer-Human Interaction (SIGCHI) and Computer Graphics (SIGGRAPH). The ACM UIST conference brings together professionals in the fields of graphical and web-user interfaces, tangible and ubiquitous computing, virtual and augmented reality, multimedia, and input and output devices.
The Student Innovation Contest has been held during the UIST conference since 2009 to innovate new interactions on state-of-the-art hardware. The participating students were given with the hardware platform to build on—this year, it was Kinoma Create, a JavaScript-powered construction kit that allows makers, professional product designers, and web developers to create personal projects, consumer electronics, and "Internet of Things" prototypes. Contestants demonstrated their creations on household interfaces, and two winners in each of three categories -- Most Creative, Most Useful, and the People’s Choice -- were awarded.
Utilizing Kinoma Create, which came with a built-in touchscreen, WiFi, Bluetooth, a front-facing sensor connector, and a 50-pin rear sensor dock, the KAIST team developed a “smart mop,” transforming the irksome task of cleaning into a fun game. The smart mop identifies target dirt and shows its location on the display built in the rod of a mop. If the user turns on a game mode, then winning scores are gained wherever the target dirt is cleaned.
The People’s Choice award was decided by conference attendees, and they voted the smart mop as their most favorite project.
Professor Tek-Jin Nam of the Department of Industrial Design at KAIST, who advised the students, said, "A total of 24 teams from such prestigious universities as Carnegie Mellon University, Georgia Institute of Technology, and the University of Tokyo joined the contest, and we are pleased with the good results. Many people, in fact, praised the integration of creativity and technical excellence our have shown through the smart mop.”
Team KAIST: pictured from right to left, Sun-Jun Kim, Se-Jin Kim, and Han-Jong Kim
The Smart Mop can clean the floor and offer users a fun game.
2014.11.12 View 10255 -
PIBOT, a small humanoid robot flies an aircraft
The 2014 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2014) took place in Chicago, Illinois, on September 14-18, 2014.
Professor David Hyunchul Shim and his students from the Department of Aerospace Engineering, KAIST, presented a research paper entitled “A Robot-machine Interface for Full-functionality Automation Using a Humanoid” at the conference.
The robot called “PIBOT,” a pint-sized, tiny humanoid robot, uses a mixture of flight data and visuals to fly an airplane, capable of identifying and operating all of the buttons and switches in the cockpit of a normal light aircraft designed for humans.
For now, the robot is only flying a simulator, but Professor Shim expects that “PIBOT will help us have a fully automated flight experience, eventually replacing human pilots.”
The IEEE Spectrum magazine published an article on PIBOT posted online September 18, 2014. Please follow the link below for the article:
IEEE Spectrum, September 18, 2014
Tiny Humanoid Robot Learning to Fly Real Airplanes
http://spectrum.ieee.org/automaton/robotics/humanoids/tiny-humanoid-robot-learning-to-fly-real-airplanes
2014.09.23 View 12358