• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.764-768
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• 2002

Characteristics of ohmic Co/Si/Co contacts to n-type 4H-SiC are investigated systematically. The ohmic contacts were formed by annealing Co/Si/Co sputtered sequentially. The annealings were performed at $800^{\circ}C$ using RTP in vacuum ambient and $Ar:H_2$(9:1) ambient, respectively. The specific contact resistivity$(\rho_c)$, sheet resistance$(R_s)$, contact resistance$(R_c)$, transfer length$(L_T)$ were calculated from resistance$(R_T)$ versus contact spacing(d) measurements obtained from TLM(transmission line method) structure. While the resulting measurement values of sample annealed at vacuum ambient were $\rho_c=1.0{\tiimes}10^{-5}{\Omega}cm^2$, $R_c=20{\Omega}$ and $L_T$ = 6.0 those of sample annealed at $Ar:H_2$(9:1) ambient were $\rho_c=4.0{\tiimes}10^{-6}{\Omega}cm^2$, $R_c=4.0{\Omega}$ and $L_T$ = 2.0. The physical properties of contacts were examined using XRD and AES. The results showed that cobalt silicide was formed on SiC and Co was migrated into SiC.

• 설비공학논문집
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• 제10권6호
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• pp.773-783
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• 1998

The heating system for apartment complex may be classified as old systems including central system with steam boiler(S1), gas engine driven heat pump system(S2), system using waste heat(S3) and new systems including mechanical vapor re-compression system with flashing heat exchangers(S4), system using methanol(S5), system using metal hydride (S6). The purpose of the present study is to suggest optimal heating system by technically, economically and environmentally evaluating old and new heating systems of apartment complex from 500 to 3,000 households. Economic evaluation based on the technical evaluation results which estimated heat transfer area of heat exchangers and capacity of equipments was estimated initial investment cost, annual operating cost and relative payback period by considering annual increasing rates of energy cost and interest. Environmental evaluation provided annual generation rate of carbon dioxide. Initial investment cost was cheap in the order of S6, S5, S3, S2, S4, S1, annual operating cost was cheap in the order of S1, S2, S4, S5 and relative payback period was short in the order of S6, S5, S2, S3 and S4. Relative payback period was within 8 years for all scenarios of 3,000 households, and was increased as annual increasing rates of energy cost and interest were increased. As transportation pipe length was increased twice, payback period was increased by 1.4~2.6 time. The effect of temperatures of waste gas and waste water on the relative payback period was small within 0.8 years. The annual generation rate of carbon dioxide was big in the order of S4, S2 and S1. S4 was the most economic system among whole scenarios when S1 was replaced with other scenarios.

• 한국태양에너지학회 논문집
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• 제36권2호
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• pp.41-51
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• 2016

A solar air heater was designed for supplementary domestic heating. The absorber plate had a series of protruding notches which had triangular openings on the front surface of the absorber plate to direct partial air flow to the rear surface and to enhance the convective heat transfer to the flowing air. The height of the opening as well as the opening configuration was determined by preceding numerical simulations. The experimental model had an absorber plate of 0.78-m width and 1.0-m length which was coated with black paint. The air temperature increased as much as $18^{\circ}C$ for $90-m^3/h$ flow rate when the absorber plate was inclined by $45^{\circ}$ for a clear-day solar irradiation of about $906W/m^2$. The collector efficiency ranged from 69 to 74%. Considering the simplicity of the structure and low manufacturing cost, the solar air heater might have competence as an auxiliary heating device for domestic use. On-site experimental results are presented with discussion for various solar irradiations and air flow conditions.

• 전자공학회논문지SC
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• 제39권1호
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• pp.66-75
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• 2002

IEEE 802.11a에 의해 규정되어진 데이터 전송속도 12Mbps, 부호화 율 1/2, 구속장이 7인 무선 LAN용 비터비 디코더의 이론적인 성능분석을 위해서 Cramer법칙을 이용하여 전달함수를 구하고 가산성 백색 가우시안 잡음 환경하에서 각 구속장 별 첫 번째 사건에서의 에러 확률과 비트 에러 확률을 구하였다. 설계과정에서는 4 비트 연성판정을 위해 입력 심볼을 16단계로 양자화 하였으며, 역 추적을 위한 방식으로 메모리를 사용하는 대신 레지스터 교환방식을 사용함으로써 다수결 결정이 가능한 구조를 제시하였다. 구현과정에서는 12Mbps 고속의 데이터를 처리하기 위해 파이프 라인을 적용한 병렬구조를 갖는 비터비 디코더와 가산성 백색 가우시안 잡음 설계를 FPGA 칩을 사용하여 구현하여 실시간 환경에서 성능검증을 하였다.

• 한국환경과학회지
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• 제11권8호
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• pp.819-827
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• 2002

Laboratory scale experiments were conducted to evaluate the performance of a biofilter for eliminating dimethyl sulfide(DMS). A commercial compost/pine bark nugget mixture served as the biofilter material for the experiments. The gas flow rate and DMS concentration entering the filter were varied to study their effect on the biofilter efficiency. The operating parameters, such as the residence time, inlet concentration, pH, water content, and temperature, were all monitored throughout the filter operation. The kinetic dependence of the DMS removal along the column length was also studied to obtain a quantitative description of the DMS elimination. High DMS removal efficiencies(>95％) were obtained using the compost filter material seeded with activated sludge. DMS pollutant loading rates of up to 5.2 and 5.5 g-DMS/m$^3$/hr were effectively handled by the upflow and downflow biofilter columns, respectively. The macrokinetics of the DMS removal were found to be fractional-order diffusion-limited over the 9 to 25 ppm range of inlet concentrations tested. The upflow column had an average macrokinetic coefficient(K$\_$f/) of 0.0789 $\pm$ 0.0178 ppm$\^$$\sfrac{1}{2}$//sec, while the downflow column had an average coefficient of 0.0935 $\pm$ 0.0200 ppm$\^$$\sfrac{1}{2}$//sec. Shorter residence times resulted in a lower mass transfer of the pollutant from the gas phase to the aqueous liquid phase, thereby decreasing the efficiency.

• 한국산업보건학회지
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• 제23권4호
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• pp.367-373
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• 2013

Objectives: Employee exposure record refers to a record containing information about environmental (workplace) monitoring or measuring of a toxic substance or harmful physical agent. The aims of this study were to examine problems related to exposure records and provide some amendments to the Korean Industrial Safety & Health Act for the effective management of chemical substances under the law. Methods: This study performed a literature search and review on legal provisions related to exposure records of a number of different countries, including Korea, the USA, Japan, EU, Germany, and the UK. They were compared and investigated and the amendment of articles was suggested. Results: The results of this study were provided as suggested amendments to the related act. There were a variety of ways of improvement, including a 30-year retention period and the introduction of new access methods, contents, transfer, and maintenance methods. All exposure data elements have to be standardized, including reference to a similar exposure group (SEG), sampling strategy, and circumstances of exposure (e.g., date, shift length, use of personal protective equipment, etc.). The SEGs are described by process, job, task, and environmental agent. Conclusions: This study is expected to provide for the amendment of the related act in order to ensure effective management of exposure records and is helpful for solving the cause and result of occupational disease by keeping exposure records according to the Industrial Safety & Health Act.

• 한국중재학회지:중재연구
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• 제24권1호
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• pp.45-58
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• 2014

It is a well recognised rule in international law that the property of aliens cannot be taken. The question of whether indirect expropriation and government regulatory measures require compensation is an important issue in international investment law. Bilateral investment treaties and other investment agreements contain brief and general indirect expropriation provisions. These focus on the effect of government action and do not address the distinction between compensable and non-compensable regulatory actions. It is generally accepted that a state is not responsible for loss of property or for other economic disadvantages resulting from bona fide general taxation accepted as within the police power of states, provided it is not discriminatory. Yukos Oil Company is a Russian oil and gas company engaged in exploration, refining, and marketing activities. It is one of the largest oil and gas companies in the world. Yukos Oil Company has its production operations in Russia and markets its products in Europe. An international tribunal ordered the Russian government to compensate a group of Spanish investors for the losses they suffered when Russia seized the Yukos Oil Company on July 26, 2012. This has been the subject of several judicial proceedings and academic publications. This paper explores which circumstances do not lead to taxation amounting to expropriation. The author suggests that under the following circumstances, taxation would not amount to expropriation. First, taxation should be non-discriminatory. Also a lawful exercise of the taxation powers of governments would not amount to expropriation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.160-160
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• 2010

In this work, we investigate ohmic contacts to p-type GaN using a Pt/Cu/Au metallization scheme in order to achieve low resistance and thermally stable ohmic contact on p-GaN. An ohmic contact formed by a metal electrode deposited on a highly doped InGaN/GaN superlattice sturucture on p-GaN layer. The specific contact resistance is $1.56{\times}10^{-6}{\Omega}cm^2$ for the as-deposited sample, $1.35{\times}10^{-4}{\Omega}cm^2$ for the sample annealed at $250^{\circ}C$ and $6.88{\times}10^{-3}{\Omega}cm^2$ for the sample annealed at $300^{\circ}C$.

• 콘크리트학회논문집
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• 제26권5호
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• pp.635-642
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• 2014

일반적인 슬래브대신에 중공슬래브를 사용함으로 콘크리트의 무게를 줄일 수 있으며 비용도 절감시킬 수 있다. 하지만 중공슬래브는 복부에서 콘크리트단면의 감소와 전단철근을 배근할 수 없기 때문에 전단에 대한 검토가 필요하다. 본 연구에서는 프리캐스트-프리스트레스트 중공슬래브를 실험을 기반으로 전단강도 평가를 수행하였다. 전단강도실험은 6개의 실험체를 제작하고 수행하였으며, 전단강도는 현행기준인 EC2, ACI, EN1168, AASHTO로 평가하여 비교분석하였다.

• Composites Research
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• 제15권6호
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• pp.1-7
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• 2002

VARTM공정에서는 수지유동을 빠르게 하기 위해 투과촉진층이 사용되는데 투과촉진층과 섬유층 사이의 수지 속도차가 크다. VARTM제품은 길이에 비해서 두께가 얇으나 두 가지 다른 유통 매질 사이에 발생하는 lead-lag 유통을 관찰하기 위해서는 두께 방향을 고려한 3차원해석이 요구된다. 그런데 3차원 해석에 있어서 계산 시간이 문제가 된다. 일반 PC로 절점수가 많은 3차원 문제를 해석하려면 오랜 시간이 소요되므로 비실용적이다. 그래서 본 연구에서는 dual-scale 기법을 도입하여 전체 영역은 2.5차원으로 해석하고 주요한 관심 영역만을 3차원으로 해석하였다. 2.5차원 시뮬레이션만으로 예측하기 어려운 lead-lag 유동과 같은 특이한 유동 경향을 국부적인 3차인 해석을 통해서 발견학 수 있었다. 본 연구에서 개발된 global-local 해석기술은 일반 PC에서 적당한 계산 시간 내에 균일하지 않은 유동 매질 사이를 지나는 유동흐름의 특성 분석에 효과적으로 사용될 수 있다.