• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 제5회 학술대회 논문집 일렉트렛트 및 응용기술연구회
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• pp.25-28
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• 2003

Ozone is a strong and useful oxidizing gas for the fabrication of oxide thin films. In order to obtain high quality oxide thin films, higher ozone concentration is necessary. In this paper an ozone condensation system was evaluated from the viewpoint of an ozone supplier for oxide thin film growth. Ozone was condensed by an adsorption method and the ozone concentration reached 8.5 mol% in 2.5 h after the beginning of the ozone condensation process, indicating high effectiveness of the condensation process. Ozone was continuously desorbed from the silica gel by the negative pressure. We found the decomposition in the ozone concentration negligible if the condensed ozone is transferred from the ozone condensation system to the film growth chamber within a few minutes.

• Journal of Advanced Marine Engineering and Technology
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• 제33권1호
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• pp.37-43
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• 2009

This paper is performed to develop a tripple-tube exchanger which can improve the system efficiency. Three different tube diameters are compacted by one body(tripple-tube) to recover waste heat from heat exchanging among the fluids. With this, the tripple-tube shows higher cooling capacity than the double-tube after comparing between those two systems. The results of this paper are basic data to design the optimum tripple-tube heat exchanger.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.1192-1195
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• 2003

A highly condensed ozone gas be transferred to the superconductor thin film growth chamber because ozone is strong oxidizing gas. In order to obtain high quality oxide thin films, higher ozone concentration is necessary. In this paper an ozone condensation system was evaluated from the viewpoint of an ozone supplier for oxide thin film growth. Ozone was condensed by an adsorption method and the ozone concentration reached 8.5 mol% in 2.5 h after the beginning of the ozone condensation process, indicating high effectiveness of the condensation process. Ozone was continuously desorbed from the silica gel by the negative pressure.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권2호
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• pp.98-106
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• 2006

This paper proposes to position and speed control of interior Permanent magnet synchronous motor(IPMSM) drive without mechanical sensor. Also, this paper develops a adaptive fuzzy controller based fuzzy logic control for high performance of PMSM drives. In the proposed system, fuzzy control is used to implement the direct controller as well as the adaptation mechanism. A Gopinath observer is used for the mechanical state estimation of the motor. The observer was developed based on nonlinear model of IPMSM, that employs a d-q rotating reference frame attached to the rotor. A Gopinath observer is implemented to compute the speed and position feedback signal. The validity of the proposed scheme is confirmed by various response characteristics.

• 설비공학논문집
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• 제14권6호
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• pp.468-476
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• 2002

This paper deals with heat and mass transfer characteristics and performance evaluation of a counter flow double-tube condenser for a multi-component refrigerant mixture. The local heat and mass transfer characteristics of ternary zeotropic refrigerant mixtures composed of HFC32/HFC125/HFC134a are evaluated for a counter flow double-tube condenser cooled by water. Then, the local values of vapor quality, thermodynamic states at bulk vapor, vapor-liquid interface and bulk liquid, heat flux and condensation mass flux are obtained. The heat exchange performance for ternary zeotropic refrigerant mixtures composed of HFC32/HFC125/HFC134a on the total pressure drop and the heat transfer characteristics are also compared with those for R404A, R410A, R502, R22, R32, Rl23 and R134a.

• Journal of Information Technology Applications and Management
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• 제12권2호
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• pp.163-184
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• 2005

The purpose of this research is to examine the major determinants affecting the usage and performance of information technologies in Daedeok Valley and Zhongguancun venture firms. The development of the research model is based on the theoretical linkages of IDT (Innovation Diffusion Theory) and TAM(Technology Acceptance Model). Seven hypotheses are derived and tested using regression analysis. The results from regression analysis suggest that the usage of Information technologies is affected by innovation characteristics (perceived usefulness) as well as organizational characteristics (top management support, employee capability on information technology acceptance) in Daedeok Valley venture firms. But, The results from regression analysis suggest that the usage of Information technologies is affected by innovation characteristics (perceived usefulness), organizational characteristics (top management support, employee capability on information technology acceptance), and external pressure (environmental uncertainty, intensity of competition) in Zhongguancun venture firms.

• 기계저널
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• 제16권2호
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• pp.84-91
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• 1976

An experimental investigation of the natural circulating boiling flow characteristic in three cases of annulus with different outer diameter, and the effect of annular gap size on the burnout behavior is presented. The experimental work was conducted for each case of test section at system pressure of $1kg/cm^2$ and inlet subcooling $0-20^{\circ}C$ in the full range of throttling ratio. As the result, the following facts were found. 1) With the increase of ${\Delta}T_{sub}$, $D_{2}$ and A/A_{o}$, $q_{BO}$ increases on the whole, and with the decrease of ${\Delta}T_{sub}$ and $D_{2}$, hydrodynamic instability is accelerated to happen prematually. 2)With the increase of ${\Delta}T_{sub}$, $D_{2}$ and A/A_{o}$ burnout characteristic shows the high velocitylow quality burnout, and with the decrease, low-velocity-high quality burnout. 3)With the decrease of A/A_{o}$, hyddrodynamic instability is singnificantly restrained and the difference of $q_{BO}$ in each $D_2$ under same condition is gradually reduced, finally converging into $1.9{\times}10^{5}kcal/m^{2}-hr$.

• 에너지공학
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• 제20권1호
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• pp.30-35
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• 2011

2중관형과 판형 열교환기에 에틸렌 클리콜-물 수용액으로 만들어진 아이스슬러리를 적용하는 경우의 유동 및 열적 특성을 규명하기 위하여 실험을 수행하였다. 아이스슬러리의 질량유속과 얼음 분율은 각각 800에서 3500 kg/$m^2s$과 0에서 25%이었다. 실험을 통해, 압력강하와 열전달율은 질량유속과 얼음 분율에 따라 증가하였다. 그러나 얼음 분율의 효과는 높은 질량유속 영역에서는 크지 않은 것으로 나타났다. 낮은 질량유속에서는 압력강하와 열전달율의 급속한 증가가 질량 유속에 관계되는 것으로 나타났다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 춘계종합학술대회
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• pp.590-593
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• 2003

금속 산화물 박막 제작에 유효한 산화가스로 오존가스를 채택했다. 고품질의 산화 박막을 얻기 위해 고농도 오존이 필요하여 오존 농축 시스템을 구축 및 평가하였다. 이 장치는 실리카겔로 오존의 선택 흡착을 이용해, 농축 공정 시작 후 유입 농도 8.5 mol%가 검출되는 2.5 h에서 농축이 완료되고, 진공 배기로 고농도 오존가스를 생성하였으며, 성막 장치까지 가스가 공급되는 몇 분 동안은 자연분해 효과를 무시할 수 있었다.

• 대한전자공학회논문지
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• 제18권1호
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• pp.16-24
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• 1981

Delay-lock loop(DLL)는 상단관련이 있는 두 파형 사이의 지연차이를 추적하는한 최적장치이다. 본 논문에서는 지연시간이 n- 로 확장된 한 DLL의 구조와 동기상실 주파수등 저역주파수대의 성능이 해석되었다. 본 DLL은 correlator와 개선된 PN 신호장치로 구성되었으며,상관 특성은 확장된 S-커브의 형태를 가지고 있다. 잡음이 크더라도 추적범위와 초기동기시간이 좋은 특성을 가지고 있다. 3- DLL을 1- DLL과 비교하면 직렬동기방식에서 초기동기시간이 3배나 빠르며, doppler shift에 대한 저항이 2배나 큰 것으로 나타났다.