• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
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• pp.116-120
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• 2011

In this paper, we studied the optimization of the screen pringting method for crystalline silicon solar cell fabrication. The 156 * 156 mm2 p-type silicon wafers with $200{\mu}m$ thickness and $0.5-3{\Omega}cm$ resistivity were used after texturing, doping, and passivation. Screen printing method is a common way to make the c-Si solar cell with low-cost and high-efficiency. We studied the optimized condition for screen printing with crystalline silicon solar cell as changing the printing direction (finger line or bus bar), finger width, and mesh angle. As a result, the screen printing with finger line direction showed higher finger height and better conversion efficiency, compared with one with bus bar direction. The experiments with various finger widths and mesh angles were also carried out. The characteristics of solar cells was obtained by measuring light current-voltage, optical microscope and electroluminescence.

• 한국해양환경ㆍ에너지학회지
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• 제17권4호
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• pp.318-323
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• 2014

해상에서 사고선박을 예인하기 위해서는, 예상되는 바람과 조류 등의 해상상태에서, 선정된 예인선들의 예인력과 예인방향을 이용하여 피예인선의 선속과 방향을 추정하여야 한다. 본 논문에서는 사고선박의 다양한 예인계획에 따른 예인상태 추정 방법을 연구하였다. 기존 전산 프로그램을 사용하여 계산된 피예인선의 정면방향 선속과 저항을 가져오는 방법과, 초기 예인상태에서 선정된 예인선들에 의한 피예인선의 전진방향 선속과 저항을 계산하는 방법, 그리고 안정된 예인상태에서 피예인선의 전진방향 선속과 저항을 계산하는 방법을 제안하였다. 이들 계산 방법은 전산 프로그램으로 구현되었으며, 이 프로그램은 피예인선의 상태를 적절히 추정할 수 있는 유용한 프로그램으로 확인되었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.1173-1174
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• 2010

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1994년도 춘계학술대회 논문집
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• pp.59-62
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• 1994

Tact Electrical conductivity. optical absorption spectra of poly(p-phenylene vinylene) and their dependence on stretching are discussed in detail. The conductivity in the parallel direction to the stretching is higher over one order in magnitude than that in the perpendicular direction to the stretching is higher over one order in magnitude than that in the perpendicular direction to the stretching. The photocurrent spectrum for the ligh polarized parallel to the chain direction is much enhanced in lower photon energy compared with that for the light polarized perpendicular to that direction. The result may be originated in the difference of energies which is needed to photogenerate carriers wi th the light polarized parallel and perpendicular to the chain stretched direction.

• 대한기계학회논문집B
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• 제20권5호
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• pp.1700-1716
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• 1996

The two-dimensional, unsteady, laminar conservation equations for mass, momentum, energy and species transport in the gas phase and mass, momentum and energy in the liquid phase are solved simultaneously in spherical coordinates in order to study heating and vaporization of a droplet entrained in the oscillating flow. The numerical solution gives the velocity and temperature distribution in both gas and liquid phase as a function of time. When the gas flow oscillates around an vaporizing droplet, the liquid flow circulates in the clockwise or counterclockwise direction and the temperature distribution in the liquid phase changes its shapes, depending on the gas fow direction. When the gas flow changes its direction of circulating liquid flow is opposite to the gas flow, forming two vortex circulating in the opposite direction. During the heating period, the difference in the maximum and minimum temperature is large, followed by the almost uniform temperature slightly below the boiling temperature. The mass and heat transfer from the droplet depend on the droplet temperature, droplet diameter and the magnitude of relative velocity, giving the droplet lifetime different from the d$^{2}$-law.

• Journal of the Korean Wood Science and Technology
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• 제42권2호
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• pp.193-206
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• 2014

Residual performance of old architectural wood which has been damaged was measured using Nondestructive Evaluation (NDE). The wood Pole Tester was used to assess ultrasonic velocity inside wood and drill resistance was determined using an IML-resistograph. For ultrasonic measurements squared timber and circular timber's measurements were separately conducted with 1,300 m/s as the standard ultrasonic velocity. The standard wood samples divided into two parts; a non-sound area (below the standard), and a sound area (above the standard). Furthermore, schematization of wood was compared with results naked eye observation. The drilling resistance test was performed for both length and thickness direction in wood. The internal of the drilling was set at 30 cm (length direction), 5 cm (width direction) and 30cm (thickness direction). A non-sound area was defined as that 1) amplitude is below 20% and 2) carbonization and deterioration are related.

• 한국수소및신에너지학회논문집
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• 제19권4호
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• pp.283-290
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• 2008

In this paper, experiments with an air-breathing proton exchange membrane fuel cell (PEMFC) for mobile devices were carried out according to cathode conditions. These conditions are defined by the cathode flow field plate type (the channel type, the open type) and the cathode surface direction. Single-cell and 6-cell stack were used in the experiments. The experimental results showed that the open-type cathode flow field plate gave a better performance than the small channel type. In the experiments related to the direction of the slits on the cathode flow field plate, the horizontal slit cell was better than the vertical one. With respect to the cathode surface direction, when the cathode surface is placed in the direction normal to the ground, the PEMFC generated more stable power in the mass transport loss region. Since stable power in the mass transport region is closely related to the air supply, computational fluid dynamics (CFD) analysis for air-breathing PEMFC of different cathode surface directions was performed.

• 한국해양공학회지
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• 제21권1호
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• pp.1-6
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• 2007

While a typhoon is traveling, characteristics of its wind fields are continuously changing, producing severe changes in local water level and wave conditions, especially, when a typhoon comes into shallow water. However, there have not been many studies related to local typhoon effects, especially, considering real time changes of wind direction related to the coastal topography. In the study, the characteristics of the wind field by typhoon and topographical characteristics in shallow water are considered, as well as conditions of wave climate estimation. These are performed by the SWAN (Simulating waves nearshore) model, in order to estimate the growth of wave energy due to the wind field. It can be strongly suggested that the wave energy of theof an inner bay should be estimated when the direction of the bay entrance and the wind direction of the typhoon are identical. The result of the numerical calculations is in better agreement with the observed data than the result of the conventional estimation techniques.

• 한국재료학회지
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• 제33권6호
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• pp.251-256
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• 2023

This study aims to examine the correlation between microstructures and the mechanical properties of two high-strength API X70 linepipe steels with different specimen directions and Moaddition. The microstructure of the Mo-added steel has an irregularly shaped AF, GB matrix with pearlite because of the relatively large deformation in the non-recrystallization temperature region, while that of the Mo-free steel shows a PF matrix with bainitic microstructure. In the Mo-added steel, the M/A (martensite-austenite) in granular bainite (GB) and pearlite act as crack initiation sites with decreased upper shelf energy and an increased ductile to brittle transition temperature (DBTT). Regardless of Mo addition, all of the steels demonstrate higher strength and lower elongation in the T direction than in the L direction because of the short dislocation glide path and ease of pile-up at grain boundaries. In addition, the impact test specimens with T-L direction had a lower impact absorbed energy and higher DBTT than those with the L-T direction because the former exhibit shorter unit crack path compared to the latter.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2005년도 추계학술발표회
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• pp.324-325
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• 2005