MAG
-
Spintronics: A high wire act by Nanowerk News
An article by Nanowerk News on the integration of ferromagnetic nanowire arrays on grapheme substrates was published. Professor Bong-Soo Kim from the Department of Chemistry, KAIST, led the research in conjunction with Hanyang University and Samsung in Korea.
http://www.nanowerk.com/news/newsid=22204.php
Posted: Jul 25th, 2011
Spintronics: A high wire act
(Nanowerk News) Graphene is a promising material for a wide range of applications due to its remarkable mechanical and electronic properties. An application of particular interest is spin-based electronics, or spintronics, in which the spin orientation of an electron is used to perform circuit functions in addition to its charge. Bongsoo Kim and colleagues from KAIST, Hanyang University and Samsung in Korea now report the integration of ferromagnetic nanowire arrays on graphene substrates, opening up a route for the construction of graphene-based spintronic devices using nanowires as spin-injecting contacts ("Epitaxially Integrating Ferromagnetic Fe1.3Ge Nanowire Arrays on Few-Layer Graphene").
The spin of an electron is a property that, like charge, can be used to encode, process and transport information. However, spin information is easily lost in most media, which has made spintronics difficult to realize in practice. In graphene, on the other hand, spin can be preserved for longer due to its peculiar electron transport properties. "Low intrinsic spin–orbit coupling, long spin diffusion lengths and vanishing hyperfine interaction are features of graphene that make it a promising medium for spin transport," explains Kim.
Scanning electron microscopy image of vertical iron germanide nanowires grown on graphene. (© ACS 2011)
A prerequisite for the realization of spintronic devices based on graphene is its integration with ferromagnetic contacts to allow spin injection. Kim and his co-workers found that nanowires of iron germanide (Fe1.3Ge) serve as efficient contacts for this purpose. "Iron germanide nanowires show low resistivity and room-temperature ferromagnetism, and they are compatible with existing complementary metal–oxide–semiconductor technologies," says Kim.
To produce the atomically well-defined interfacial contact between the nanowires and the graphene surface needed for optimum device performance, the researchers deposited the contacts by an epitaxial method based on chemical vapor transport. Through careful adjustment of deposition parameters such as carrier gas flow rate and reaction temperature, the researchers produced vertically aligned nanowires that are closely lattice-matched to the graphene sheets (see image).
Initially preparing the graphene sheets on a substrate of silicon oxide allowed the researchers to isolate the final nanowire–graphene structure by etching and then transfer it to another substrate, greatly expanding the versatility of the approach. It is a delicate process, however. "It is necessary to transfer the graphene films onto the substrate very carefully in order to avoid folding and wrinkling of the graphene," says Kim.
Source: Tokyo Institute of Technology
2011.07.26 View 11035 -
Wireless electric trams at Seoul Amusement Park begin full operations.
Photo by Hyung-Joon Jun
IMMEDIATE RELEASE
Wireless electric trams at Seoul Amusement Park begin full operations.
KAIST’s On-Line Electric Vehicle (OLEV) becomes an icon of green technology, particularly for young students who aspire to transform their nation into the “vanguard of sustainability.”
Seoul, South Korea, July 19, 2011—As young students wrap up their school work before summer vacation in late July, Seoul Grand Park, an amusement park located south of Seoul, is busily preparing to accommodate throngs of summer visitors. Among the park’s routine preparations, however, there is something new to introduce to guests this summer: three wireless electric trams have replaced the old diesel-powered carts used by passengers for transportation within the park.
The Korea Advanced Institute of Science and Technology (KAIST) and the city of Seoul held a ceremony this morning, July 19, 2011, to celebrate their joint efforts to adopt a green public transportation system and presented park visitors with the three On-Line Electric Vehicles (OLEVs), which will be operated immediately thereafter. Approximately one hundred people, including science high school students across the nation, attended the ceremony and had a chance to ride the trams.
KAIST unveiled the prototype of an electric tram to the public in March 2010, and since then it has developed three commercial trams. The Korean government and the institute have worked on legal issues to embark on the full-scale commercialization of OLEV, and the long awaited approval from the government on such issues as standardization of the OLEV technology and road infrastructure, regulation of electromagnetic fields and electricity safety, and license and permits for vehicle eligibility, finally came through.
The On-Line Electric Vehicle (OLEV) is no ordinary electric car in that it is remotely charged via electromagnetic fields created by electric cables buried beneath the road. Unlike other currently available electric cars, OLEV can travel unlimited distances without having to stop to recharge. OLEV also has a small battery onboard, which enables the vehicle to travel on roads that are not equipped with underground power cables. This battery, however, is only one-fifth of the size of a conventional electric vehicle battery, resulting in considerable savings in the cost, size, and weight of the vehicle.
The OLEV project was initiated in 2009 as a method of resolving the battery problems of electric cars in a creative and disruptive way. KAIST came up with the idea of supplying electricity directly to the cars instead of depending solely on the onboard battery for power. Since then, the university has developed core technologies related to OLEV such as the “Shaped Magnetic Field in Resonance (SMFIR),” which enables an electric car to collect the magnetic fields and convert them into electricity, and the “Segment Technology,” which controls the flow of electromagnetic waves through an automatic power-on/shut-down system, thereby eliminating accidental exposure of the electromagnetic waves to pedestrians or non-OLEV cars.
According to KAIST, three types of OLEV have been developed thus far: electric buses, trams, and sport utility vehicles (SUVs). The technical specifications of the most recently developed OLEV (an electric bus), the OLEV research team at the university said, are as follows:
· Power cables are buried 15cm beneath the road surface.
· On average, over 80% power transmission efficiency is achieved.
· The distance gap between the road surface and the underbody of the vehicle is 20cm.
· The OLEV bus has a maximum electricity pickup capacity of 100kW.
· The OLEV bus complies with international standards for electromagnetic fields (below 24.1 mG).
The eco-friendly electric trams at Seoul Grand Park consume no fossil fuels and do not require any overhead wires or cables. Out of the total circular driving route (2.2km), only 16% of the road, 372.5m, has the embedded power lines, indicating that OLEV does not require extensive reconstruction of the road infrastructure. The city government of Seoul signed a memorandum of understanding with KAIST in 2009 as part of its initiatives to curtail emissions from public transportation and provide cleaner air to its citizens. Both parties plan to expand such collaboration to other transportation systems including buses in the future.
KAIST expects the OLEV technology to be applied in industries ranging from transportation to electronics, aviation, maritime transportation, robotics, and leisure. There are several ongoing international collaborative projects to utilize the OLEV technology for a variety of transportation needs, such as inner city commute systems (bus and trolley) and airport shuttle buses, in nations including Malaysia, US, Germany, and Denmark.
# # #
More information about KAIST’s On-Line Electric Vehicle can be found at http://olev.co.kr/en/index.php. For any inquiries, please contact Lan Yoon at 82-42-350-2295 (cell: 82-10-2539-4303) or by email at hlyoon@kaist.ac.kr.
2011.07.22 View 15683 -
Scientists develop highly efficient industrial catalyst
http://english.yonhapnews.co.kr/business/2011/07/14/48/0501000000AEN20110714009600320F.HTML
SEOUL, July 15 (Yonhap) -- South Korean scientists said Friday that they have developed a highly efficient nanoporous industrial catalyst that can have a considerable impact on chemical and oil-refining sectors.
The team of scientists led by Ryoo Ryong, a chemistry professor at the Korea Advanced Institute of Science and Technology (KAIST), said the solid zeolite compound developed in the laboratory has a reaction speed five to 10 times faster than that of conventional materials.
Zeolite, which is made from silica and aluminium, is frequently used as an absorbent, water purifier and in nuclear reprocessing, although it is mainly employed in the chemical industry.
The annual size of the zeolite market is estimated at US$2.5 billion with output using the material topping $30 billion. At present, 41 percent of all catalysts used in the chemical sector are nano-scale zeolite materials.
The KAIST team said that because the new zeolite is made up of different sized pores, the material can be used as a catalyst when existing materials are unable to act as a changing agent.
"Existing zeolites only have pores under 1 nanometer in diameter, but the new material has holes that range from 1 nanometer to 3.5 nanometers, which are all arranged in a regular honeycomb arrangement," Ryoo said. A nanometer is one-billionth of a meter.
He said the ability to have both micro- and meso-sized pores is key to the faster reaction speed that is an integral part of raising efficiency. The South Korean researchers used a so-called surfactant process to make the different sizes of pores.
The development is a breakthrough because researchers and companies such as Exxon Mobil Corp. have been trying to build zeolite with different sizes of pores for the past two decades without making serious headway. There are more than 200 different types of zeolites in the world.
Ryoo, who received funding from the government, has requested intellectual property rights for the discovery, which has been published in the latest issue of Science magazine. He also developed another zeolite in the past that can transform methanol to gasoline up to 10 times more efficiently than existing catalysts.
Exxon Mobil has expressed interest in the two zeolites made by Ryoo"s team. Undisclosed South Korean petrochemical companies have also made inquiries that may lead to commercial development in the future.
"There are some technical issues to resolve, mainly related with mass production and stability," the scientist said.
He said full-fledge production will be determined by how much companies are willing to spend on research to speed up development that can bring down overall production costs.
The KAIST team said it took two years to make the new zeolite, which can be custom made to meet specific needs.
(END)
2011.07.15 View 12539
-
Biomimetic Carbon Nanotube Fiber Synthesis Technology Developed
The byssus of the mussel allows it to live in harsh conditions where it is constantly battered by crashing waves by allowing the mussel to latch onto the seaside rocks. This particular characteristic of the mussel is due to the unique structure and high adhesiveness of the mussel’s byssus.
KAIST’s Professor Hong Soon Hyung (Department of Material Science and Engineering) and Professor Lee Hae Shin (Department of Chemistry) and the late Professor Park Tae Kwan (Department of Bio Engineering) were able to reproduce the mussel’s byssus using carbon nanotubes.
The carbon nanotube, since its discovery in 1991, was regarded as the next generation material due to its electrical, thermal, and mechanical properties. However due to its short length of several nanometers, its industrial use was limited.
The KAIST research team referred to the structure of the byssus of the mussel to solve this problem.
The byssus is composed of collagen fibers and Mefp-1 protein which are in a cross-linking structure. The Mefp-1 protein has catecholamine that allows it to bind strongly with the collagen fiber.
In the artificial structure, the carbon nanotube took on the role of the collagen fibers and the macromolecular adhesive took on the role of the catecholamine. The result was a fiber that was ultra-light and ultra-strong.
The results of the experiment were published in the Advanced Materials magazine and is patent registered both domestically and internationally.
2011.06.20 View 13171
-
From Pencil Lead to Batteries: the Unlimited Transformation of Carbon
Those materials, like lead or diamond, made completely up of Carbon are being used in numerous ways as materials or parts. Especially with the discovery of carbon nanotubes, graphemes, and other carbon based materials in nanoscale, the carbon based materials are receiving a lot of interest in both fields of research and industry.
The carbon nanotubes and graphemes are considered as the ‘dream material’ and have a structure of a cross section of a bee hive. Such structure allows the material to have strength higher than that of a diamond and still be able to bend, be transparent and also conduct electricity. However the problem up till now was that these carbon structures appeared in layers and in bunches and were therefore hard to separate to individual layers or tubes.
Professor Kim Sang Wook’s research team developed the technology that can assemble the grapheme and carbon nanotubes in a three dimensional manner.
The team was able to assemble the grapheme ad carbon nanotubes in an entirely new three dimensional structure. In addition, the team was able to efficiently extract single layered grapheme from cheap pencil lead.
Professor Kim is scheduled to give a guest lecture in the “Materials Research Society” in San Francisco and the paper was published in ‘Advanced Functional Materials’ magazine as an ‘Invited Feature Article’.
2011.05.11 View 11593
-
Artificial Photosynthesis Technology Developed using Solar Cell Material
Humanity is facing global warming and the exhaustion of fossil fuel. In order to remedy these problems, efforts to produce fuel without the production of carbon dioxide using solar energy continues constantly.
KAIST’s Professor Park Chan Beom and Professor Ryu Jeong Ki’s research teams of the department of Material Science and Engineering has developed an artificial photosynthesis system that mimics the photosynthesis in nature using solar cell technology.
The development of the technology is sure to pave the way to ‘Eco-Friendly Green Biological Process’.
Photosynthesis is the process by which a biological entity produces chemical products like carbohydrates using physical and chemical reactions using solar energy as its energy source.
Professor Park’s team was able to develop the artificial photosynthesis technology with a biological catalyst as its basis.
The result of the experiment was published in ‘Advanced Materials’ magazine on the 26th of April edition and has been patented.
2011.05.11 View 11231
-
Genetic Cause of ADHD (Attention Deficit Hyperactivity Disorder) Found
The cooperative research team consisting research teams under Professor Kim Eun Joon and Professor Kang Chang Won of the department of Biological Sciences discovered that ADHD arises from the deficiency of GIT1 protein in the brain’s neural synapses.
ADHD (Attention Deficit Hyperactivity Disorder) is found in around 5% of children around the world and is a disorder where the child becomes unable to concentrate, show over the top responses, and display impulsive behavior.
The research team found that the difference between children with ADHD and those without it is one base in the GIT1 gene. The difference of a single base causes the underproduction of this protein, and those children with low levels of the protein had a higher probability to develop ADHD.
In addition, further evidence was provided when the research team conducted mice experiments. Those mice with low levels of GIT1 exhibited impulsive and exaggerated reactions like humans with ADHD, had learning disabilities, and produced abnormal brain waves. And upon injecting these mice with cure for ADHD, the symptoms of ADHD disappeared.
The impulsive behavior of ADHD children disappears as the child enters adulthood and a similar pattern was found in mice. A mice with low levels of GIT1 showed impulsive behaviors when 2 months old, but these behaviors disappeared as it got older to around 7 months old (equivalent to 20~30 years old for humans).
Professor Kim Eun Joon commented that there has to be equilibrium between mechanisms that excite the neurons and mechanisms that calm the neurons, but the lack of GIT1 leads to the decrease in the mechanisms that calm the neurons which causes the impulsive behavior of ADHD patients.
In addition, Professor Kang Chang Won commented that the results of the experiment has been receiving rave reviews and is being seen as the new method in the production of the cure for ADHD.
The result of the experiment was published in the online edition of Nature Medicine magazine.
2011.04.30 View 11262
-
A Light Weight, Energy Effcient Household Polysomnography (PSG) System Developed
A smart ‘household polysomnography (PSG) system’ was developed by domestic research team.
Professor Yoo Hui Joon and his research team of KAIST’s department of Electricity and Electronic Engineering successfully developed a PSG system that is light weight and has high performance levels. The conventional PSG systems were complex with numerous lines and wires.
The PSG is used to monitor biological signals during sleep and the monitored results are used to diagnose and cure sleep-related illnesses and disorders. However because of restrictions like the size of the machine, impurities, and the change in environment, multiple trials over several days were required to obtain accurate data.
The system developed by the research team is lighter than a q-tip so as to not disturb the patient’s sleep. It also has Intelligent Circuit (IC) that detects when sensors come detached and automatically replaces the sensor with another sensor thereby allowing continual monitoring of the user.
A low-power consuming circuit was implemented allowing the entire system to run continuously on a single coin battery for 10 hours which effectively decreased the weight of the system and simultaneously allows for uninterrupted monitoring of the user over the entire sleep cycle.
Even a remote diagnosis system can be implemented. The user will don the PSG and sleep at home, ensuring that a normal heat beat rate, brain waves, breathing, etc. will be monitored. The data procured overnight can be sent to the experts online who will be able to diagnose remotely.
The research team plans on performing research in cooperation with the KAIST hospital and U-Healthcare research.
The research result is winning worldwide rave. The system was announced in the International Solid-State Circuits Conference (ISSCC) and was published in ISSCC magazine and in Japan’s NIKKEI Electronics January edition.
2011.03.25 View 12307
-
Professor Min Beom Ki develops metamaterial with high index of refraction
Korean research team was able to theoretically prove that a metamaterial with high index of refraction does exist and produced it experimentally.
Professor Min Beom Ki, Dr. Choi Moo Han, and Doctorate candidate Lee Seung Hoon was joined by Dr. Kang Kwang Yong’s team from ETRI, KAIST’s Professor Less Yong Hee’s team, and Seoul National University’s Professor Park Nam Kyu’s team. The research was funded by the Basic Research Support Program initiated by the Ministry of Education, Science, and Technology and Korea Research Federation.
The result of the research was published in ‘Nature’ magazine and is one of the few researches carried out by teams composed entirely of Koreans.
Metamaterials are materials that have physical properties beyond those materials’ properties that are found in nature. It is formed not with atoms, but with synthetic atoms which have smaller structures than wavelengths.
The optical and electromagnetic waves’ properties of metamaterials can be altered significantly which has caught the attention of scientists worldwide.
Professor Min Beom Ki’s team independently designed and created a dielectric metamaterial with high polarization and low diamagnetism with an index of refraction of 38.6, highest synthesized index value.
It is expected that the result of the experiment will help develop high resolution imaging system and ultra small, hyper sensitive optical devices.
2011.02.23 View 17547
-
OLEV Safety Confirmed by International Standards
On September 19, KAIST announced that the electromagnetic (EM) field levels of its online electric vehicle (OLEV) measured in June and September of this year demonstrated verification of its safety.
Last June, the EM field level of OLEV installed at the Seoul Grand Park was measured by the Korea Research Institute of Standards and Science (KRISS) to test its harmfulness to human. The results were 0.5 ~ 61mG which is within the national and international standards of 62.5mG.
KRISS measured EM field levels on 22 spots on the side of and at the center of OLEV at a fixed distance (30cm) but variable heights (5cm~150cm) according to the national standard of measurement methods for electromagnetic fields of household appliances and similar apparatuses with regard to human exposure (IEC 62233).
In addition, another testing took place on September 13 following a request by National Assemblywoman Young-Ah Park, a member of the National Assembly’s Education, Science and Technology Committee, who has raised an issue on the safety of OLEV. This testing session was held by EMF Safety, Inc., an institution designated by Park, and it tested the EM field level of the same OLEV train that was tested in June.
As a result, the September measurements were well within the national and international standards with 0~24.1mG. The test was conducted under the presence of third party to produce a fair and objective result.
As reference, the EM field level results are well within the American IEEE electromagnetic field standards of 1,100 mG.
The September measurements were produced by Park’s recommendation of following the criteria specified in the measurement procedures of IEC 62110, “Electric and magnetic field levels generated by AC power systems to public exposure,” which were 15 measurements at a fixed 20cm distance at the side of and from the center of OLEV with variable heights of 50cm~150cm.
2010.09.27 View 12926 -
Nanowire crystal transformation method was newly developed by a KAIST research team.
Figure 1
Schematic illustration of NW crystal transformation process. FeSi is converted to Fe3Si by high-temperature thermal annealing in diluted O2 condition and subsequent wet etching by 5% HF.
Figure 2
Low-resolution TEM images of FeSi; Fe3Si@SiO2 core—shell; Fe3Si NW after shell-etching; and Scale bars are 20 nm
Professor Bongsoo Kim of the Department of Chemistry, KAIST, and his research team succeeded to fabricate Heusler alloy Fe3Si nanowires by a diffusion-driven crystal structure transformation method from paramagnetic FeSi nanowires. This methodology is also applied to Co2Si nanowires in order to obtain metal-rich nanowires (Co) as another evidence of the structural transformation process. The newly developed nanowire crystal transformation method, Professor Kim said, would be valuable as a general method to fabricate metal-rich silicide nanowires that are otherwise difficult to synthesize.
Metal silicide nanowires are potentially useful in a wide array of fields including nao-optics, information technology, biosensors, and medicine. Chemical synthesis of these nanowires, however, is challenging due to the complex phase behavior of silicides.
The metal silicide nanowires are grown on a silicon substrate covered with a thin layer of silicon oxide via a simple chemical vapor deposition (CVD) process using single or multiple source precursors. Alternatively, the nanowires can be grown on the thin silicon oxide film via a chemical vapor transport (CVT) process using solid metal silicide precursors.
The CVT-based method has been highly effective for the syntheses of metal silicide NWs, but changing the composition of metal silicide NWs in a wider range, especially achieving a composition of a metal to silicon, has been quite difficult.
Thus, developing efficient and reliable synthetic methods to adjust flexibly the elemental compositions in metal silicide NWs can be valuable for the fabrication of practical spintronic and neonelectronic devices.
Professor Kim expliained, “The key concept underlying this work is metal-enrichment of metal silicide NWs by thermal diffusion. This conversion method could prove highly valuable, since novel metal-rich silicide NWs that are difficult to synthesize but possess interesting physical properties can be fabricated from other metal silicide NWs.”
The research result was published in Nanao Letters, a leading peer-reviewed journal, and posted online in early August 2010.
2010.08.25 View 11675 -
KAIST's OLEV Best Model of Creative Growth Engine
Various models of electric vehicles designed to replace the internal combustion automobiles face significant problems as they invariably failed to overcome the limitations involving lithium battery in terms of power capacity, weight, raw materal price, recharging time and preparation of charging stations. Worst of all, the limited supply of lithium will eventually raise its price sky high when all cars use lithium batteries, and the economic value of electric cars will be lost.
KAIST"s online electric vehicle project (OLEV) seeks to resolve these fundamental problems involving electric vehicles that have so far been developed. KAIST OLEV, a project to develop a new growth engine for the nation and lead the future of global automotive industry, is an entirely new concept: the electric vehicle picks up power from underground power supplier lines through the non-contact magnetic charging method, while either running or standing. This is the first eco-friendly and economic automotive system that can resolve the problems inherent to previously-developed electric vehicles, according to the KAIST OLEV Project Center.
In February 2009, KAIST researchers first proved that up to 80 percent power conveyance is possible through a gap of 1 centimeter from the power line, and in July they successfully supplied power to a bus -- up to 60 percent across a 12 cm gap from the power line embedded in the ground -- using power supply and pick-up devices they developed. In this process, KAIST has secured the core technologies for maximizing power efficiency and minimizing the cost of installing the non-contact power supply system. KAIST has established the Online Electric Vehicle Co., Ltd., to undertake business activities related to the OLEV project, including the IPR on power supply and pick-up devices, parts and accessories and commercial promotion. A demonstration event is scheduled for Aug. 13, Thursday.
The impact of the development of the OLEV technology on the energy and environment issues and the overall economy will be enormous. In case a half of the total automobiles running in Korea, or 6 million vehicles, are replaced with OLEV, electric power produced by just two of the nation"s atomic power plants will be enough to operate them all, and the nation will be able to reduce crude oil import by 35 million barrels worth U.S.$3 billion a year (supposing $80 per barrel).
Korea"s export of OLEV units will in the future surpass the present level of overseas sale of conventional cars. When nations use online electric vehicles in large numbers, their demand for CO2-free power plants will grow. Korea has cutting-edge technology in the construction of atomic power plants. As a world leader in the area of nuclear power plant, Korea will enjoy new opportunities to contribute to the global advancement of atomic power generation as well as transportation industries.
Korea still shares a small portion of the world"s automobile market estimated to worth some 2,000 trillion Korean won. But commercialization of the OLEV technology worldwide will greatly enhance Korea"s global automotive market share. Successful development of the online electric vehicle requires preemptive investment and positive support by the government for the ultimate purpose of resolving energy and environment problems.
If and when domestic enterprises secure technological supremacy in the next generation automobile market with their online electric vehicles which will replace the 100-year-old combustion engine, it will be the most desirable shortcut to raising Korea"s international competitiveness. OLEV promises to be the model of creative growth engine in the 21st century.
2009.07.30 View 17349