science+and+engineering
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Ultra-High Strength Metamaterial Developed Using Graphene
New metamaterial has been developed, exhibiting hundreds of times greater strength than pure metals.
Professor Seung Min, Han and Yoo Sung, Jeong (Graduate School of Energy, Environment, Water, and Sustainability (EEWS)) and Professor Seok Woo, Jeon (Department of Material Science and Engineering) have developed a composite nanomaterial. The nanomaterial consists of graphene inserted in copper and nickel and exhibits strengths 500 times and 180 times, respectively, greater than that of pure metals. The result of the research was published on the July 2nd online edition in Nature Communications journal.
Graphene displays strengths 200 times greater than that of steel, is stretchable, and is flexible. The U.S. Army Armaments Research, Development and Engineering Center developed a graphene-metal nanomaterial but failed to drastically improve the strength of the material.
To maximize the strength increased by the addition of graphene, the KAIST research team created a layered structure of metal and graphene. Using CVD (Chemical Vapor Deposition), the team grew a single layer of graphene on a metal deposited substrate and then deposited another metal layer. They repeated this process to produce a metal-graphene multilayer composite material, utilizing a single layer of graphene. Micro-compression tests within Transmission Electronic Microscope and Molecular Dynamics simulations effectively showed the strength enhancing effect and the dislocation movement in grain boundaries of graphene on an atomic level.
The mechanical characteristics of the graphene layer within the metal-graphene composite material successfully blocked the dislocations and cracks from external damage from traveling inwards. Therefore the composite material displayed strength beyond conventional metal-metal multilayer materials. The copper-graphene multilayer material with an interplanar distance of 70nm exhibited 500 times greater (1.5GPa) strength than pure copper. Nickel-graphene multilayer material with an interplanar distance of 100nm showed 180 times greater (4.0GPa) strength than pure nickel.
It was found that there is a clear relationship between the interplanar distance and the strength of the multilayer material. A smaller interplanar distance made the dislocation movement more difficult and therefore increased the strength of the material. Professor Han, who led the research, commented, “the result is astounding as 0.00004% in weight of graphene increased the strength of the materials by hundreds of times” and “improvements based on this success, especially mass production with roll-to-roll process or metal sintering process in the production of ultra-high strength, lightweight parts for automobile and spacecraft, may become possible.” In addition, Professor Han mentioned that “the new material can be applied to coating materials for nuclear reactor construction or other structural materials requiring high reliability.”
The research project received support from National Research Foundation, Global Frontier Program, KAIST EEWS-KINC Program and KISTI Supercomputer and was a collaborative effort with KISTI (Korea Institute of Science and Technology Information), KBSI (Korea Basic Science Institute), Stanford University, and Columbia University.
A schematic diagram shows the structure of metal-graphene multi-layers. The metal-graphene multi-layered composite materials, containing a single-layered graphene, block the dislocation movement of graphene layers, resulting in a greater strength in the materials.
2013.08.23 View 14274 -
Liver Damage Mechanism of Hepatitis C Proven
KAIST researchers found mechanics behind a Hepatitis C virus, thereby taking a step closer to the development of a cure for Hepatitis C.
Professor Choi Chul Hui (Department of Biological and Brain Engineering) and Professor Shin Eui Chul (Graduate School of Medical Sciences) proved, for the first time in the world, the mechanism behind liver damage of a patient with Hepatitis C.
It is anticipated that this discovery will allow for the development of a Hepatitis C cure that has no side effects and little Liver damage.
Hepatitis C is an immune response of the body to the Hepatitis C virus and causes liver irritation.
Around 170million people are infected with Hepatitis C worldwide including 1% of the Korean population. Once infected, most cases turn into chronic cases and may lead to liver cancer.
However it was impossible to infect Hepatitis C within a test tube cell environment until 2005 and up till then Chimpanzees were used to study the virus which proved to be a huge barrier to research.
The research team used cells infected with Hepatitis C virus and found out that the virus works by increasing the destruction of cells by the TNF-a protein responsible for the cell’s immune response.
In addition the protein structure of the virus that causes this reaction was successfully found.
Conventionally the Hepatitis C medication focused on the suppressing the growth of the virus and therefore had many side effects.
The experimental results allow new medication aimed at suppressing the actual mechanism of liver damage to be discovered.
The result was selected as the cover dissertation of the September Edition of the Hepatolog magazine.
2012.09.11 View 11494 -
The KAIST & GIT team developed a power generation technology using bendable thin film nano-materials.
Figure description: Flexible thin film nanomaterials produce electricity.
Can a heart implanted micro robot operate permanently?
Can cell phones and tiny robots implanted in the heart operate permanently without having their batteries charged?
It might sound like science fiction, but these things seem to be possible in the near future. The team of Prof. Keon Jae Lee (KAIST, Dept. of Materials Science and Engineering) and Prof. Zhong Lin Wang (Georgia Institute of Technology, Dept. of Materials Science and Engineering) has developed new forms of highly efficient, flexible nanogenerator technology using the freely bendable piezoelectric ceramic thin film nano-materials that can convert tiny movements of the human body (such as heart beats and blood flow) into electrical energy.
The piezoelectric effect refers to voltage generation when pressure or bending strength is applied to piezoelectric materials. The ceramics, containing a perovskite structure, have a high piezoelectric efficiency. Until now, it has been very difficult to use these ceramic materials to fabricate flexible electronic systems due to their brittle property.
The research team, however, has succeeded in developing a bio-eco-friendly ceramic thin film nanogenerator that is freely bendable without breakdown.
Nanogenerator technology, a power generating system without wires or batteries, combines nanotechnology with piezoelectrics that can be used not only in personal mobile electronics but also in bio-implantable sensors or as an energy source for micro robots. Energy sources in nature (wind, vibration, and sound) and biomechanical forces produced by the human body (heart beats, blood flow, and muscle contraction/relaxation) can infinitely produce nonpolluting energy. (Nanogenerator produces electricity by external forces: http://www.youtube.com/watch?v=tvj0SsBqpBw)
Prof. Keon Jae Lee (KAIST) was involved in the first co-invention of “High Performance Flexible Single Crystal Electronics” during his PhD course at the University of Illinois at Urbana-Champaign. This nanogenerator technology, based on the previous invention, utilized the similar protocol of transferring ceramic thin film nano-materials on flexible substrates and produced voltage generation between electrodes.
Prof. Zhong Lin Wang (Georgia Tech, inventor of the nanogenerator) said, “This technology can be used to turn on an LED by slightly modifying circuits and operate touchable flexible displays. In addition, thin film nano-materials (‘barium titanate’) of this research have the property of both high efficiency and lead-free bio compatibility, which can be used in future medical applications.” This result is published in November online issue of ‘Nano Letters’ ACS journal.
<Video>
Youtube link: http://www.youtube.com/watch?v=tvj0SsBqpBw
Thin Film Nanogenerator produces electricity by external forces.
2010.11.23 View 13976 -
Prof. Cho Wins Best Paper Award
KAIST Prof. Nam-Zin Cho of the Department of Nuclear and Quantum Engineering, won the Best Thesis Award in the nuclear reactor physics category at the 2008 Winter Meeting of the American Nuclear Society held on Nov. 9-13 in Reno, Nevada.
His paper, entitled "Thermal Feedback Transient Analysis of a Pebble Fuel Based on the Two-Temperature Homogenized Model," was jointly authored by Hwi Yu and Jong-Un Kim under the guidance of Prof. Cho.
Prof. Cho was elected a fellow of the American Nuclear Society in 2001 and has served as the deputy editor of the Nuclear Science and Engineering, the research journal of the American Nuclear Society, since 1999.
2008.12.09 View 13341 -
Women Leaders Awarded Honorary Degrees
Korea"s two women leaders, Park Geun-hye, former President of the Grand National Party, and Lee Gil-ya, chairperson of the Gachon Gil Foundation, a major medical services organization, were awarded honorary doctorate degrees by KAIST, Korea"s state-run science and technology research university, on Feb. 29.
It is the first time in the school"s 37-year history that women have been awarded honorary doctorate degrees. Park and Lee were conferred with the honor during the university"s 2008 graduation ceremony in recognition of their achievements in social services.
KAIST President Suh Nam-pyo said that the university decided to confer honorary doctorate degrees to Park and Lee, who both have educational backgrounds in the fields of engineering and science, in order to present role models to female students in science and engineering who still make up a relatively small percentage of the total enrollment at KAIST and throughout Korean universities.
"Our graduates and future students will strive to make meaningful contributions to the nation and the world, just as the two women leaders have done so well, for so many years," said Suh in his commencement address.
Female students constitute 23 percent of the total enrollment of 7,800, including graduate and doctorate students.
The honorary doctorate citation said Park Geun-hye, a graduate of the Department of Electronic Engineering, Sogang University in Seoul, has exerted strenuous efforts for the advancement of science and technology education and women"s social role. Among other things, Park called for the launching of a "second-stage science and technology revolution" during her 2007 presidential campaign. She declared science and technology as "the most crucial area of national development and survival" and instituted seven-point strategies to innovate the nation"s science and technology. Those strategies are specifically aimed at increasing investment in science and technology, fostering a world-class science and technology university and creating science-friendly curriculum at schools.
Lee Gil-ya, a widely-revered medical doctor, has demonstrated outstanding leadership in education, culture, journalism and business management, according to her citation. Throughout her brilliant professional career, she has vigorously pursued her lifelong goal of philanthropy, social service and patriotism. In particular, her dedication to nurturing young talents is widely recognized in Korea.
2008.03.05 View 12846
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Professor Jongwon Lee wins Korean Engineering Award
Professor Jongwon Lee wins Korean Engineering Award
Professor Jongwon Lee of the department of Mechanical Engineering won the 7th Korean Engineering Award conferred by the Ministry of Science and Technology and Korean Science and Engineering Foundation.
Professor Lee is a world-famous scholar in the field of ‘dynamics and vibration of rotors’ and his work in 1993, ‘Vibration Analysis of Rotors’, is highly recognized as a creative and practical research on the dynamics of rotors.
The Korean Engineering Award is conferred on domestic scientists who have made world-level research achievements in the engineering field by the Ministry of Science and Technology and Korean Science and Technology Foundation every two years.
2007.01.11 View 12201