• 한국산업정보학회논문지
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• 제18권6호
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• pp.25-30
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• 2013

나노크기 MOSFET 공정에서 회로의 신뢰도에 영향을 미치는 음 바이어스 온도 불안정성(NBTI), 핫 캐리어 주입(HCI), 시간 의존 유전체 파손(TDDB) 등과 같은 노화 현상들에 의해서 회로 성능의 심각한 저하를 가져올 수 있다. 그러므로, 본 논문에서는 디지털회로에서 발생할 수 있는 노화를 극복할 수 있는 적응형 보상 회로를 제안하고자 한다. 제안된 보상회로는 노화에 의해 감소하는 회로 성능을 적응적으로 보상해 주기 위해서 노화 정도에 따라 파워스위치 폭을 조절할 수 있고, 순방향 바디 바이어싱 전압을 걸어줄 수 있는 파워 게이팅 구조를 사용하여서 45nm의 공정기술에서 설계되었다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제5권3호
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• pp.454-467
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• 2013

A practical Ship Inner Shell Optimization Method (SISOM), the purpose of which is to improve the safety of the seagoing transport ship by decreasing the maximum Still Water Bending Moment (SWBM) of the hull girder under all typical loading conditions, is presented in this paper. The objective of SISOM is to make the maximum SWBM minimum, and the section areas of the inner shell are taken as optimization variables. The main requirements of the ship performances, such as cargo hold capacity, propeller and rudder immersion, bridge visibility, damage stability and prevention of pollution etc., are taken as constraints. The penalty function method is used in SISOM to change the above nonlinear constraint problem into an unconstrained one, which is then solved by applying the steepest descent method. After optimization, the optimal section area distribution of the inner shell is obtained, and the shape of inner shell is adjusted according to the optimal section area. SISOM is applied to a product oil tanker and a bulk carrier, and the maximum SWBM of the two ships is significantly decreased by changing the shape of inner shell plate slightly. The two examples prove that SISOM is highly efficient and valuable to engineering practice.

• Journal of Welding and Joining
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• 제29권5호
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• pp.95-98
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• 2011

Recently, there is a growing tendency that fine-pitch electronic devices are increased due to higher density and very large scale integration. Finer pitch printed circuit board(PCB) is to be decrease insulation resistance between circuit patterns and electrical components, which will induce to electrical short in electronic circuit by electrochemical migration when it exposes to long term in high temperature and high humidity. In this research, the effect of soldering flux acting as an electrical carrier between conductors on electrochemical migration was investigated. The PCB pad was coated with OSP finish. Sn3.0Ag0.5Cu solder paste was printed on the PCB circuit and then the coupon was treated by reflow process. Thereby, specimen for ion migration test was fabricated. Electrochemical migration test was conducted under the condition of DC 48 V, $85^{\circ}C$, and 85 % relative humidity. Their life time could be increased about 22% by means of removal of flux. The fundamentals and mechanism of electrochemical migration was discussed depending on the existence of flux residues after reflow process.

• 한국산업정보학회논문지
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• 제10권1호
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• pp.1-8
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• 2005

다중 반송파 기술과 CDMA 기술이 결합된 MC-CDMA 시스템은 주파수 선택적 페이딩에 의한 신호감쇄를 완화시키면서 높은 전송률에 대한 요구를 만족시킬 수 있는 전송방식이다. 본 논문에서는 전송률이 서로 다른 다양한 서비스들을 지원하기 위한 새로운 비동기 MC-CDMA 시스템을 제안한다. 제안된 시스템에서는 전송속도에 따라 병렬 부 채널의 수(P)를 조절함으로서 다중전송률 시스템을 구성하며, 이런 시스템 성능을 수식적으로 분석한다 시스템 성능은 평균 비트 오류율로 나타내었다. 여기서 평균 비트 오류율은 무선 채널을 통과한 수신신호의 간섭전력을 수치적으로 구한 후, 가우시안 근사방법을 이용하여 얻는다. 제안된 시스템과 단일 데이터율을 갖는 MC-CDMA시스템의 성능과 비교한다.

• 멤브레인
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• 제23권1호
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• pp.54-60
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• 2013

PEGDA/PETEDA dendrimer 막은 PEGDA에 5~15 wt%의 PETEDA dendrimer를 첨가하고 UV를 조사하여 제조하였다. 제조된 막의 특성은 FT-IR, $^1H$-NMR 그리고 DSC를 통해 분석하였다. PEGDA/PETEDA dendrimer 막의 유리전이온도($T_g$)는 PETEDA dendrimer의 함량이 증가할수록 감소하였다. $CH_4$에 대한 $CO_2$ 투과 특성은 PETEDA dendrimer의 함량과 압력을 변화시키며 조사하였다. 10 wt%의 PETEDA dendrimer를 포함하는 막의 투과도는 162.2 barrer였으나 $CO_2/CH_4$ 이상분리 인자는 31.8로 가장 높게 나타났다.

• 한국산학기술학회논문지
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• 제12권9호
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• pp.4147-4152
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• 2011

변형된 CMA는 CMA에 비해 고차 신호점을 등화 시 보다 적은 수의, 균등한 간격을 갖는 모듈러스를 이용함으로써 정상상태 성능 개선과 고차 신호점으로의 확장이 용이하다. 본 논문에서는 변형된 CMA에 가변 수렴상수를 적용하여 정상상태 성능을 더욱 개선하여 다른 경판정 알고리즘으로의 전환 없이도 충분히 만족스러운 성능을 달성할 수 있음을 보인다. 새로운 두 가지 수렴상수 가변 방법을 제안하고, 이를 적용한 변형된 CMA의 성능 개선을 모의실험을 통해 CMA와 고정 수렴상수의 변형된 CMA에 대해 확인하였다.

• Journal of the Korean Wood Science and Technology
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• 제31권6호
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• pp.83-88
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• 2003

The woodceramics are porous amorphous carbon and glassy carbon composite materials. Woodceramics attracted a lot of attention in recent years because they are environmentally friendly and because of their unique functional characteristics such as catalysis, moisture absorption, deodorization, purification, carrier for microbial activity, specific stiffness, corrosion and friction resistance, and their electromagnetic shielding capacity. In this paper, we made new products of clay-woodceramics to investigate the industrial analysis and ethylene gas adsorption for basic data of building- and packging- materials keeping fruit fresh for a long time. Clay-woodceramics were carbonized for 3 h of heating in a special furnace under a gas flow of nitrogen(15 ml/min.) from 3 layers-clay-woodparticleboard made from pallet waste wood, phenol- formaldehyde resin(hereafter PF, Non volatile content:52%, resin content 30%), and clay(10%, 20% and 30%). Carbonization temperature was 400℃, 600℃ and 800℃. Experimental results shows that the higher the carbonization temperature, the higher the fixed carbon and the lower the volatile contents. The higher the clay content, the more the ash content. The higher the carbonization temperature, the more the ethylene gas adsorption. Carbonization temperature of 800℃ gave the best reslts as same as that of white charcoal and activated carbon.(800℃-clay-woodceramic: 5.36 ppm, white charcoal: 5.66 ppm, activated carbon: 5.79 ppm) The clay contents did not make difference of ethylene gas adsoption.

• World Technopolis Review
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• 제7권1호
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• pp.2-14
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• 2018

Nowadays, we are standing in front of the $4^{th}$ Industrial Revolution that is featured by a great range of new and advanced technologies that influences all the domains of economies and industries. The great question that this revolution raises is how it can lead to a future that reflects the peoples' common objectives and values on how these advanced technologies can affect the life and transform the economic, social, cultural, and human environment. It is commonly agreed that to be adapted to these changes and needs and shape a society with competitive economies with highly-skilled individuals, we need to encourage innovation, entrepreneurship, new knowledge generation and exchange and true and effective collaboration and communication. In this complex scene, education seems to have a central and critical role on finding new ways of developing expertise and innovation within the existing knowledge procedures, with more and better cooperation between the key players. This paper argues the concepts, opportunities and challenges that are related to the learning ecosystem towards the needs raised by the $4^{th}$ Industrial Revolution. The education is discussed as catalyst but also as carrier of innovation and innovation practices and the basis of a relevant framework is presented that takes into account all the aspects, domains and key players of educational world and interacting domains. Having introduced the ideas of innovation, collaboration and technology advancement in this environment, this paper also presents a real case of practice, focusing on how more than 5.000 schools around Europe succeeded the last four (4) years to implement innovation activities in a collaborative way and under a unique but also flexible pedagogical innovation framework.

• 한국분말재료학회지
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• 제8권3호
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• pp.151-156
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• 2001

MgO based nanocomposite powder including ferromagnetic iron particle dispersions, which can be available for the magnetic and catalytic applications, was fabricated by the spray pyrolysis process using ultra-sonic atomizer and reduction processes. Liquid source was prepared from iron (Fe)-nitrate, as a source of Fe nano-dispersion, and magnesium (Mg)-nitrate, as a source of MgO materials, with pure water solvent. After the chamber were heated to given temperatures (500~$^800{\circ}C$), the mist of liquid droplets generated by ultrasonic atomizer carried into the chamber by a carrier gas of air, and the ist was decomposed into Fe-oxide and MgO nano-powder. The obtained powders were reduced by hydrogen atmosphere at 600~$^800{\circ}C$. The reduction behavior was investigated by thermal gravity and hygrometry. After reduction, the aggregated sub-micron Fe/MgO powders were obtained, and each aggregated powder composed of nano-sized Fe/MgO materials. By the difference of the chamber temperature, the particle size of Fe and MgO was changed in a few 10 nm levels. Also, the nano-porous Fe-MgO sub-micron powders were obtained. Through this preparation process and the evaluation of phase and microstructure, it was concluded that the Fe/MgO nanocomposite powders with high surface area and the higher coercive force were successfully fabricated.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.141-141
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• 2010

The effect of thermal anneal on the characteristics of structural properties and the enhancement of luminescence and photovoltaic (PV) characteristics of silicon-rich silicon-nitride films were investigated. By using an ultra high vacuum ion beam sputtering deposition, B-doped silicon-rich silicon-nitride (SRSN) thin films, with excess silicon content of 15 at. %, on P-doped (n-type) Si substrate was fabricated, sputtering a highly B doped Si wafer with a BN chip by N plasma. In order to examine the influence of thermal anneal, films were then annealed at different temperature up to $1100^{\circ}C$ under $N_2$ environment. Raman, X-ray diffraction, and X-ray photoemission spectroscopy did not show any reliable evidence of amorphous or crystalline Si clusters allowing us concluding that nearly no Si nano-cluster could be formed through the precipitation of excess Si from SRSN matrix during thermal anneal. Instead, results of Fourier transform infrared and X-ray photoemission spectroscopy clearly indicated that defective, amorphous Si-N matrix of films was changed to be well-ordered thanks to high temperature anneal. The measurement of spectral ellipsometry in UV-visible range was carried out and we found that the optical absorption edge of film was shifted to higher energy as the anneal temperature increased as the results of thermal anneal induced formation of $Si_3N_4$-like matrix. These are consistent with the observation that higher visible photoluminescence, which is likely due to the presence of Si-N bonds, from anneals at higher temperature. Based on these films, PV cells were fabricated by the formation of front/back metal electrodes. For all cells, typical I-V characteristic of p-n diode junction was observed. We also tried to measure PV properties using a solar-simulator and confirmed successful operation of PV devices. Carrier transport mechanism depending on anneal temperature and the implication of PV cells based on SRSN films were also discussed.