• Journal of Advanced Marine Engineering and Technology
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• 제7권1호
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• pp.64-78
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• 1983

In nucleate boiling, bubbles are created by the expansion of entrapped gas or vapor at small cavities in the surface of heat transfer. Namely, surface roughness is the important factor of heat transfer. This paper deals with the characteristics of boiling curve according to surface roughness. Freon-113 is used as the experimental fluid. The results are as follows; 1. In the case of the same as "q=C$\Delta$T$^{n}$ ", the lower numberical index "n", the larger heat transfer coefficient and the lower wall superheat "$\Delta$T" is obtained for the rougher surface. 2. In the working of every kind of heat transfer sruface with boiling, improvement of capabilities of heat transfer can be devised by adding suitable roughness on the heat transfer surface. 3. When the metal nets of moderate mesh number are established, the capabilities of heat transfer can be improved in evaporation of liquid in vessels. But in the case that the sucession of bubbles in checked by using the nets which are too tight, the generation of bubbles union decreases critical heat flux. decreases critical heat flux.

• Journal of Advanced Marine Engineering and Technology
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• 제28권1호
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• pp.75-82
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• 2004

In this research, a computer analysis has been developed for predicting the Pipe pressure of the intake and exhaust manifold in a small single cylinder engine. To get the boundary conditions for a numerical analysis one dimensional and unsteady gas dynamic calculation is performed by using the MOC(Method Of Characteristics). The main numerical parameters are engine revolutions. to calculate the Pulsating flow which the intake and exhaust valves are working. The distributions of the exhaust pipe pressures were influenced strongly to the cylinder pressures and the shapes of exhaust pressure variation were similar to the Inside of cylinder pressure As the engine revolutions are increased. the intake pressure was lower than ambient pressure. The amplitude of exhaust pressure had increased and the phase of cylinder pressure $P_c$ is delayed and the amplitude of cylinder pressure were increased.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1999년도 추계 학술발표회 논문집
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• pp.149-154
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• 1999

This paper describes a passive safety injection system with free piston Stirling pump working withabundant decay heat in the nuclear reactor during the hypothetical accident. The water column in the tube assembly connected from the hot chamber to the cold chamber in the pump oscillates periodically due to thermal volume changes of non-condensable gas in each chamber. The oscillating pressure in the water column is converted into the pumping power with a suction-and-bleed type valve assembly. In this paper a dynamic model describing the frequency of oscillation and pumping pressure is developed. It was found that the pumping pressure is a function of the temperature difference between the chambers. Also, the frequency oscillation depends on the length of the tube with water column.

• 한국표면공학회지
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• 제33권5호
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• pp.349-355
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• 2000

Indium tin oxide (ITO) thin films have been deposited on PET (polyethylene terephthalate) and glass substrates by a do magnetron sputter method of powder target without heat treatments such as substrate heater and post heat treatment. During the sputtering deposition, sputtering parameters such as sputtering power, working pressure, oxygen gas mixture, film thickness and substrate-target distance are important factors for the high quality of ITO thin films. The structural, electrical and optical properties of as-deposited ITO oxide films are investigated by sputtering power, oxygen partial pressure and films thickness among the several sputtering conditions. XRD patterns of ITO films are affected by sputtering power and pressure. As the power and pressure are increased, (411) and (422) peaks of ITO films are grown strongly. Electrical resistivity is also increased, as the sputtering power and pressure are increased. Transmittance of ITO thin films in the visible light ranges is lowered with an increase of sputtering power and film thickness. Reflectance of ITO films in infra-red region is decreased, as the power and pressure is increased.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 추계학술대회
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• pp.428-430
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• 2009

본 논문은 RF 마그네트론 스퍼터링 시스템을 이용하여 p-Si (100) 기판위에 증착된 C축 배향을 가지는 ZnO 박막의 특성을 분석하고 있다. 증착 전력, 공정 압력, 반응가스로 사용된 산소 가스의 비율과 같은 증착 조건들을 변화시켰을 때, ZnO 박막의 결정구조의 변화를 분석한다. 증착된 ZnO 박막의 결정 구조는 주사 전자 현미경(scanning electron microscope, SEM)을 이용하여 조사되었다. 분석 결과 증착 파라미터들은 증착된 ZnO 박막의 결정(grain) 크기와 배향 특성에 강한 영향을 미친다는 사실을 알 수 있다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.339-345
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• 2006

This these was conducted to investigate tile characteristics of a frozen start up for a VCHP which has water as a working fluid and Nitrogen as a non-condensible gas. The tested heat pipe was made of a copper tube with the outer diameter of 12.7 mm, the length of 340 mm, and the sintered metal wick had the thickness of 0.7 mm. This experiment was conflicted under the thermal load, inclined angle and cooling conditions.

• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2005년도 추계 학술대회
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• pp.106-109
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• 2005

The ITO thin films for Top-Emitting Organic Light Emitting Devices (TOLEDs) were prepared on cell(LiF/Organic Layer/Bottom Electrode : ITO ) by FTS (Facing Targets Sputtering) system under different sputtering conditions which were varying gas pressure, input current and distance of target to target($D_{T-T}$). As a function of sputtering conditions, I-V characteristics of prepared ITO thin films on cell were measured by 4156A (HP). In the results, when the In thin films were deposited at $D_{T-T}$ 70mm and working pressure 1mTorr, the leakage current of ITO/cell was about 11[V] and 5E-6[$mA/cm^2$].

• 도시과학
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• 제9권2호
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• pp.63-68
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• 2020

In recent years, the planning of livable communities has emerged as a new paradigm. The concept of livable communities is related to both the spatial balance of working, playing, and living and the promotion of green modes of transportation, such as walking and biking. This study uses a disaggregate travel survey conducted by the Seoul Metropolitan Area in 2006. I applied a multi-level random intercept logit model to estimate the effects of land-use characteristics on the choice of green modes, holding a traveler's socio-demographic characteristics constant. The empirical results show that higher density and more mixed land-use development encourages people to walk and bike even when individuals have the same socio-economic characteristics. This paper demonstrates that land-use planning by itself can play a role in the creation of livable cities and the decline of greenhouse gas production.

• 한국가시화정보학회지
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• 제19권2호
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• pp.32-40
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• 2021

Vapor-driven solutal Marangoni flow is governed by the concentration distribution of solutes on a liquid-gas interface. Typically, the flow structure is investigated by particle image velocimetry (PIV). However, to develop a theoretical model or to explain the working mechanism, the concentration distribution of solutes at the interface should be known. However, it is difficult to achieve the concentration profile theoretically and experimentally. In this paper, to find the concentration distribution of solutes around 2D droplet, the reverse tracking method with an artificial neural network based on PIV data was performed. Using the method, the concentration distribution of solutes around a 2D droplet was estimated for actual flow data from PIV experiment.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.359-362
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• 2003

Damping systems have been widely used to various industrial structures and are mainly hydraulic and pneumatic devices nowadays. In this work, a novel damping system based on the colloidal suspension in the field of nanotechnology is investigated. The colloidal suspension consists of Iyophobic working fluid and hydrophobic-coated porous particle. The mechanism of mechanical energy dissipation in damping system based on the colloidal suspension with nano-porous particles is different from that of the existing hydraulic damping system. The absorbed energy of the damping system using colloidal suspension can be calculated through the mechanical equilibrium condition by the superficial tensions of liquid-gas Interface in the hydrophobic surface in nano-porous particles. The results from an analytic approach have a reasonable agreement with experimental results.