• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.366-370
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• 2002

GaAs has become a very popular material for the fabrication of high frequency, low noise and microwave power devices. GaAs devices are also well suited for high temperature operation because of the large band gap of this material. The standard GaAs technology and device structures have to be modified for stable operation at high temperature. In this paper, AlGaAs/GaAs HBT considering stable ohmic contact at high temperature as well as thermal effect such as self-heating effect are introduced. All the data obtained study will be used as input data for the simulator and the result will be compared with an analytical model available in this study,

• JSTS:Journal of Semiconductor Technology and Science
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• 제8권1호
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• pp.92-97
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• 2008

In this Paper, we present a scaling theory for dual material surrounding gate (DMSGTs) MOSFETs, which gives a guidance for the device design and maintaining a precise subthreshold factor for given device parameters. By studying the subthreshold conducting phenomenon of DMSGTs, the effective conductive path effect (ECPE) is employed to acquire the natural length to guide the design. With ECPE, the minimum channel potential is used to monitor the subthreshold behavior. The effect of ECPE on scaling factor significantly improves the subthreshold swing compared to conventional scaling rule. This proposed model offers the basic designing guidance for dual material surrounding gate MOSFETs.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제28회 추계학술대회
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• pp.323-329
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• 1998

The effect of humidity on friction characteristics of friction materials were studied using a pad-on-disk type friction tester. Three different friction materials containing simplified ingredients were investigated by changing the solid lubricant, graphite, MoS$_2$, and $Sb_2S_3$. A friction material without solid lubricant was also examined to study the effect of ingredients in the matrix on humidity. Friction material containing graphite showed lower friction coefficient at high humidity level than other conditions, however, friction material containing MoS$_2$ indicated higher friction coefficient at initial stage under high humidity level. Friction materials without solid lubricant and with $Sb_2S_3$ were little affected by humidity conditions.

• Journal of Magnetics
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• 제5권3호
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• pp.102-105
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• 2000

The extremely soft magnetic behaviors in the nanocrystalline $Fe_81B_11Nb_7Cu_1$ alloy annealed at 450 $\circ C$ and 550 $\circ C$ for 1 hour in a vacuum were investigated by means of the magnetoimpedance (MI) effect and the incremental permeability. Because the MI effect can be obtained only in ultra-soft magnetic materials, the improvement of magnetic softness by proper thermal treatment was carefully monitored by the MI effect for all annealed samples. The changes of the incremental permeability as a function of an external field were also measured to verify the magnetic softness along with the MI measurement.

• 한국전기전자재료학회논문지
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• 제17권4호
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• pp.443-447
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• 2004

In this study, we investigated the necessity of encapsulation layer to maximize flexibility of brittle indium-tin-oxide (ITO) on polymer substrates. And, Young's modulus (E) of encapsulation layer han a significant effect on external bending stress and the coefficient of thermal expansion (CTE) of that han a significant effect on internal thermal stress. To compare the magnitude of total mechanical stress including both bending stress and thermal stress, the mechanical stress of triple-layer structure (substrate / ITO / encapsulation layer or substrate / buffer layer / ITO) can be quantified and numerically analyzed through the farthest cracked island position. As a result, it should be noted that multi-layer structures with more elastic encapsulation material have small mechanical stress compared to that of buffer and encapsulation structure of large Young's modulus material when they were externally bent.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2000년도 International Symposium on Magnetics The 2000 Fall Conference
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• pp.466-472
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• 2000

The extremely soft magnetic behaviors in the nanocrystalline Fe$_{81}$B$_{11}$Nb$_{7}$Cu$_{1}$ alloy annealed at 450 $^{\circ}C$ and 550 $^{\circ}C$ for 1 hour respectively in a vacuum were obtained, and examined by means of the magnetoimpedance(MI) effect and the incremental permeability. Because the MI effect can be obtained only in ultra-soft magnetic materials, the improvement of magnetic softness by proper thermal treatment was carefully monitored by the MI effect for all annealed samples. The changes of the incremental permeability as a function of an external field were also measured to verify the magnetic softness along with the MI measurement.ent.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 추계학술대회 논문집
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• pp.407-414
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• 1999

Sand drain as a vertical drainage is widely used in soft ground improvement. Recently, sand, the principal source of sand drain, is running out. A laboratory model test was carried out to utilize gravel as a substitute for sand. Though which the characteristics of gravel are compared to those of sand for engineering purpose. According to the test, the settlement was found to be smaller in gravel drain than in sand drain. The increase in bearing capacity by gravel rile explains the result. The clogging effect was not found in gravel column. As a result, it is assumed that gravel is relatively acceptable as a drainage material. Gravel material seems better than sand material in bearing capacity and it is found that bearing capacity is larger when gravel is used as compaction pile than as drain from in-situ test on bearing capacity. Increase of bearing capacity with gravel pile means an effect of composite ground by stiffness of gravel material. It can lie supposed to use gravel pile instead of sand pile in view of consolidation effect and bearing capacity.

• 한국방사선학회논문지
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• 제15권2호
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• pp.191-199
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• 2021

본 연구의 목적은 경량 연자성 소재의 방사선 차폐 효과를 분석하여 군사시설에 대한 적용 가능성을 확인하는 것이다. 연자성 물질은 EMP 차폐에 효과적인 것으로 알려져 있다. 이 물질이 방사선 차폐에도 효과적이라면 군 방호에 효과적으로 적용이 가능할 것으로 예상된다. 이에 본 연구에서는 감마선 차폐 효과를 확인하기 위해 Cs-137 및 Co-60 선원을 사용하여 실험을 수행하였으며, 중성자 차폐 효과를 평가하기 위해 Monte Carlo N-Particle (MCNP) 모델링을 적용하였다. 그 결과 연자성 소재의 두께가 증가함에 따라 감마선과 중성자의 선형 감쇠 법칙에 의한 차폐성능이 향상됨을 확인할 수 있었다. 따라서 연자성 소재를 군사용 구조물 등에 적용할 경우에 방사선 차폐에 효과적이라는 것을 확인하였다.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2006년도 임시총회 및 하계학술연구발표회
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• pp.82-83
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• 2006

• 한국기계가공학회지
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• 제6권1호
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• pp.62-70
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• 2007

The development of new materials that are light-weight, yet high in strength has become vital to the machinery, aircraft and auto industries. However, there are a lot of problems with developing such materials that require expensive tools, and a great deal of time and effort. Therefore, the improvement of fatigue strength and fatigue life are mainly focused on by adopting residual stress. The fatigue crack growth rate of the Shot-peened material was lower than that of the Un-peened material. And in stage I, threshold stress intensity factor of the shot-peen processed material is high in critical parts unlike the Un-peened material. Also, fatigue crack growth exponent and number of cycle of the Shot-peened material was higher than that of the Un-peened material. That is concluded from effect of da/dN. And Fatigue life shows more improvement in the Shot-peened material than in the Un-peened material. And compressive residual stress of surface on the Shot-peen processed operate resistance force of fatigue crack propagation.