• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.508-510
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• 1995

A fiber-optic pressure sensor is fabricated with a photoelastic glass material. To remove the influence of external pertubation along the optical fiber, a new referencing technique is proposed by using two light sources. LED with 870nm wavelength is used as light source for reference signal, and LED with 660nm wavelength is used as light source for modulation signal. The fiber-optic pressure sensor system shows good linearity within the pressure range of 0 to 5 $kg/cm^2$.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 전기설비
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• pp.88-90
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• 2005

There are a lot of troubles during the transfer of the source of electric power in UPS (uninterruptible power supply system) which is indispensable to the industrial equipments. They cause blackout accidents, resulting in a great economic loss. After measuring and analyzing the transient phenomena happening during the transfer, this paper presents the solution of the troubles. The solution can be used as a basic material for maintenance and it can minimize the troubles occurring in UPS and enhance the reliability of it.

• E2M - 전기 전자와 첨단 소재
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• 제6권3호
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• pp.214-219
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• 1993

고온에서 실리콘에 인을 확산시키기 위한 새로운 고체 판상 원료를 개발하였다. Source Wafer는 거품 형태의 골결을 지닌 불활성 재료에 Yttrium metaphosphate가 들어있는 구조로 되어있다. 새로운 고체 판상 원료를 사용하여 고온에서 인을 확산시켜서 재현 가능한 Sheet resistance와 깊은 Junction을 얻었다. 일련의 한 시간 도핑 결과들로부터 새로운 고체 판상 원료의 수명은 40시간 이상인 것으로 판명되었다. 1150.deg.C에서 인의 실리콘에로의 확산에 대한 유효 확산계수와 대응되는 활성화 에너지의 값을 구하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.131-131
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• 2009

Silicon Carbide (SiC) is a material with a wide bandgap (3.26eV), a high critical electric field (~2.3MV/cm), a and a high bulk electron mobility ($\sim900cm^2/Vs$). These electronic properties allow high breakdown voltage, high-speed switching capability, and high temperature operation compared to Si devices. Although various SiC DMOSFET structures have been reported so far for optimizing performances, the effect of channel dimension on the switching performance of SiC DMOSFETs has not been extensively examined. This paper studies different channel dimensons ($L_{CH}$ : $0.5{\mu}m$, $1\;{\mu}m$, $1.5\;{\mu}m$) and their effect on the the device transient characteristics. The key design parameters for SiC DMOSFETs have been optimized and a physics-based two-dimensional (2-D) mixed device and circuit simulator by Silvaco Inc. has been used to understand the relationship. with the switching characteristics. To investigate transient characteristic of the device, mixed-mode simulation has been performed, where the solution of the basic transport equations for the 2-D device structures is directly embedded into the solution procedure for the circuit equations. We observe an increase in the turn-on and turn-off time with increasing the channel length. The switching time in 4H-SiC DMOSFETs have been found to be seriously affected by the various intrinsic parasitic components, such as gate-source capacitance and channel resistance. The intrinsic parasitic components relate to the delay time required for the carrier transit from source to drain. Therefore, improvement of switching speed in 4H-SiC DMOSFETs is essential to reduce the gate-source capacitance and channel resistance.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.358-361
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• 2002

Self-aligned MOSFETS using a polysilicon gate are widely fabricated in silicon technology. The polysilicon layer acts as a mask for the source and drain implants and does as gate electrode in the final product. However, the usage of polysilicon gate as a self-aligned mask is restricted in fabricating SiC MOSFETS since the following processes such as dopant activation, ohmic contacts are done at the very high temperature to attack the stability of the polysilicon layer. A metal instead of polysilicon can be used as a gate material and even can be used for ohmic contact to source region of SiC MOSFETS, which may reduce the number of the fabrication processes. Co-formation process of metal-source/drain ohmic contact and gate has been examined in the 4H-SiC based vertical power MOSFET At low bias region (<20V), increment of leakage current after RTA was detected. However, the amount of leakage current increment was less than a few tens of ph. The interface trap densities calculated from high-low frequency C-V curves do not show any difference between w/ RTA and w/o RTA. From the C-V characteristic curves, equivalent oxide thickness was calculated. The calculated thickness was 55 and 62nm for w/o RTA and w/ RTA, respectively. During the annealing, oxidation and silicidation of Ni can be occurred. Even though refractory nature of Ni, 950$^{\circ}C$ is high enough to oxidize it. Ni reacts with silicon and oxygen from SiO$_2$ 1ayer and form Ni-silicide and Ni-oxide, respectively. These extra layers result in the change of capacitance of whole oxide layer and the leakage current

• 보존과학연구
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• 통권17호
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• pp.123-160
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• 1996

There have been many studies and experiments regarding exhibition lighting. Many experiments on photochemical damaging effect and visibility resulted in a practice limited to assigning light levels and adjusting annual exposure time. The three damaging factors to the artifacts are intrinsicsusceptibility to absorb radiant energy, spectral distribution of light source and intensity of illumination and time of exposure. Dividing all the artfacts into three categories to suggest a recommended illuminance level causes some problems. Blue wool, for example, used as the reference material for susceptibility, is not a standard material representing museum artifacts. In the most light sensitive category, ISO class I or anything below have been excluded. The exposure time of one soure can be three times more than another sourece. The spectral distribution of the light source and the relative spectral responsibility of the artifact are not considered in the practice. So in case of very light sensitive material, the recommended illuminance is only the referring value and it is indispensable to check the characteristic of susceptibility of each artifacts. Daylighting is prevailing method to solve the psychological need of the visitors. However, it sould transparent, and should not diffused, and the green-house effect must be considered. llluminance uniformity should based on the maximum illuminance to handle the limitation of exposure for the conservation of a large sensitive object such as a painting. Damage index is not absolute reference for selecting the lighting source because it is experimented from the paper of low grade then calculated. Visibility should be increased by reducing the visual noiseand by planning of appropriate luminance contrast. This paper reviews the problems with the previous studies and experiment sand the current exhibition lighting design practice. The plan for museum showcase lighting is to check the susceptibility and to raise the visibility simultaneously.

• 설비공학논문집
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• 제26권1호
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• pp.1-7
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• 2014

A field test of a 70 kW heat pump system with flue gas heat recovery was performed by an experiment at the Korea Institute of Energy Research. The flue gas is exhausted from a 320 RT absorption chiller-heater in the heating season. Using this flue gas, source water of the heat pump is heated by a condensed-type heat exchanger in the chimney. The operating characteristics of the heat recovery heat pump system were analyzed. Based on the results of the experiments, operating maps were obtained, and an optimum operating range is suggested, in which the return and heat source water temperature are $51^{\circ}C$ and $31^{\circ}C$, respectively. Additionally, economic analysis of this system was conducted and about 50% energy cost savings can be expected in the heating season.

• 한국음향학회지
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• 제23권7호
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• pp.503-513
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• 2004

본 논문에서는 단위 음향파워에 대한 온도 변화인 열 감도 (thermal sensitivity)를 새로이 정의하였으며, 이 물리량으로 조직모사물질의 성능을 평가 할 수 있다는 것을 제안하였다. 실험에 사용된 시료는 공장에서 생산되는 식용 두부이고, 초음파의 주파수를 8 MHz로 고정하고 조사 (irradiation) 시간, 음향파워, 시료 표면으로 부터의 깊이 및 초음파 변환기와의 거리에 따른 온도 변화를 측정하였다. 아울러 깊이와 초음파 변환기와의 거리를 고정하고 일정한 음향파워 조건에서 주파수에 따른 온도 변화도 측정하였다. 측정된 온도변화를 열 감도로 변환하여 고찰한 결과 조직모사물질의 성능인자로 사용하기에 충분한 것으로 판명되었다. 특히 조직모사물질로 선택한 두부는 10 MHz 에서 열 감도가 최대로 나타났으며. 이 결과는 실제 인체 조직에서 열 감도가 주파수에 민감하게 의존 할 수 있다는 가능성을 함축하는 중요한 결과이다.

• 암석학회지
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• 제13권3호
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• pp.142-151
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• 2004

경기육괴의 남서부지역인 용인-안성지역에는 선캠브리아기 초기의 기반암으로 사료되는 고변성도의 편마암과 편암 그리고 이를 관입한 중생대 쥬라기 화강암류가 광범위하게 분포하고 있다. 이 논문에서는 용인-안성지역에 분포하는 선캠브리아기의 변성암류와 이를 관입한 쥬라기 화강암의 지구화학적 특징을 토대로 서로의 상관성을 토의하고자 하였다. 연구결과에 의하면, 변성암류의 Nd모델연대( $T_{DM}$ $^{Nd}$ )는 경기육괴의 가장 활발한 지각형성시기였던 약 2.6Ca～2.9Ga(Lee or of., 2003) 동안에 생성된 기원물질로부터 유래되었음을 지시 해준다. 그리고 Nd 모델 연대( $T_{DM}$ $^{Nd}$ )에 의하면, 흑운모 호상편마암과 석영장석질 편마암의 Nd 모델 연대는 각각 2.59Ga～2.73Ga, 2.70Ga～2.88Ga로서 석영장석질 편마암의 기원물질이 약간 더 오래된 것으로 나타났다. 따라서 이들 변성암류는 경기육괴의 가장 활발한 지각형성시기의 기원물질로부터 유래되었음을 알 수 있다. 희토류원소의 분포에 있어서, 흑운모 호상편마암은 (La/Yb)$_{N}$ 값이 37～136으로 매우 급격한 기울기를 보여주는 반면에, 앰피볼라이트의 경우 (La/Yb)$_{N}$ 값이 4.65～6.64로 거의 편평한 분포양상을 보여준다 이는 흑운모호상편마암은 분화가 상당히 일어난 기원물질로부터 유래되었음을 지시해준다. 특히 연구지역내 흑운모 호상편마암, 석영장석질 편마암과 같은 고변성도의 변성암류에서 관찰되는 희토류원소의 분포도는 초기기원물질의 특성을 그대로 보유하고 있는 것으로 볼 수 있다 그리고 인접한 중생대 화강암의 (La/Yb)$_{N}$ 과 Nd 모델연대는 각각 32～40, 1.69Ga～2.08Ga로서 기반암인 흑운모 편마암과 석영장석질 편마암과는 지구화학적 특성이 서로 다른 젊은 기원물질로부터 유래되었음을 지시해준다.

• 한국군사과학기술학회지
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• 제19권4호
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• pp.453-461
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• 2016

The paper represents the experimental analysis of the shock noise of medium caliber guns when a projectile is passed through the shielding material. In the study, the shielding material was constructed and tested in three separate experiments. The shielding material was not installed for medium caliber gun in Case 1. A medium caliber gun was fully covered with shielding material in Case 2, and another one was put with shielding material near muzzle in Case 3. In each experiment, the experimental data was compared with each other. Results showed the firing shielding material achieved a significant noise reduction in $90^{\circ}$ to the noise source. Case 3 is confirmed to be better effective than Case 2 in the near field. But, the noise reduction in the far field is small in quantity due to the low frequency. The paper is considered that further study is necessary for the shielding material which can absorb a low frequency noise in the future.