• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 춘계학술발표대회 논문집
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• pp.225-229
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• 2009

The front metal contact is one of the most important element influences in efficiency in the silicon solar cell. First of all selective of the material and formation method is important in metal contacts. Commercial solar cells with screen-printed contacts formed by using Ag paste process is simple relatively and mass production is easy. But it suffer from a low fill factor and a high shading loss because of high contact resistance. Besides Ag paste too expensive. because of depends income. This paper applied for Ni/Cu metallization replace for paste of screen printing front metal contact. Low cost Ni and Cu metal contacts have been formed by using electroless plating and electroplating techniques to replace the screen-printed Ag contacts. Ni has been proposed as a suitable silicide for the salicidation process and is expected to replace conventional silicides. Copper is a promising material for the electrical contacts in solar cells in terms of conductivity and cost. In experiments Ni/Cu metal contact applied same grid formation of screen-printed solar cell. And it has variation of different grid spacing. It was verified that the wide spacing of grid finger could increase the series resistance also the narrow spacing of grid finger also implies a grid with a higher density of grid fingers. Through different grid spacing found alteration of efficiency.

• 한국전산유체공학회지
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• 제11권2호
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• pp.62-66
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• 2006

In this paper an automated hole-finding method for overset grids is introduced which uses recursive octree-cell division. A graphic program which enables the user to do the hole-cutting with ease is also introduced. Using this program it is found that there is an optimum combination of the level of octree division and vector calculation for the efficient and fast hole finding.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.231.1-231.1
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• 2005

• 한국전자파학회논문지
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• 제12권2호
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• pp.278-284
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• 2001

본 논문에서는 기울어진 금속 경계면을 삼각형 격자법으로 해석하고, 계단 근사법과 비교하였다. 특시, 삼각형 격자법에서 금속-유전체간의 경사각도에 대한 오차 범위를 밝혔다. 그결과, 삼각형 격자법에서 경사각이 30。이상 60。이하인 경우, 계단 근사법에 비하여 정확도가 향상되고, 계산속도 및 메로미를 줄일 수 있었다. 그러나 이 범위를 벗어나는 경우, 격자의 한 변의 길이가 상대적으로 늘어나 정확한 해석이 되지 않았다.

• 한국CDE학회논문집
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• 제13권6호
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• pp.450-458
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• 2008

Recently, Cartesian grid approach has been popular to generate grid meshes for complex geometries in CFD (Computational Fluid Dynamics) because it is based on the non-body-fitted technique. This paper presents a method of an octree generation and boundary cell clipping using section curves for fast octree generation and elimination of redundant intersections between boundary cells and triangles from 3D triangular mesh. The proposed octree generation method uses 2D Scan-Converting line algorithm, and the clipping is done by parameterization of vertices from section curves. Experimental results provide octree generation time as well as Cut-cell clipping time of several models. The result shows that the proposed octree generation is fast and has linear relationship between grid generation time and the number of cut-cells.

• 대한기계학회논문집
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• 제17권1호
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• pp.182-189
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• 1993

본 연구에서는 한곳에 적응효과가 중복되는 것을 피하고 해의 변화율이 상대 적으로 큰 곳에 대해 대등한 격자 적응효과를 주는 방법을 연구하였다. 전 유동장에 서 해의 변화율을 계산하여 하한값(threshold) 보다 큰 값을 갖는 cell에 대해 같은 크기의 가중함수(weight function) 값을 갖게 한다. 하한값(threshold)은 전체 cell 수에 대해 상위의 변화율을 갖는 cell의 백분율(percentage)로부터 구한다. 이 방법 은 하한값을 직접 대입해야 한다는 단점은 있으나 변황율이 상대적으로 큰 영역에 대 해 고른 격자 적응 효과를 줌으로 해서 격자 적응의 회수를 줄일 수 있으며 해의 발달 에 긍정적인 격자를 생성할 수 있다.

• 한국농공학회지
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• 제39권1호
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• pp.64-74
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• 1997

A CELTHYM(CEll-based Long-term HYdrologic Model), a pre-processor and a post-processor that can be integrated with geographic information system(GIS) were developed to predict the stream flow from the small agricultural watershed on the daily basis. The CELTHYM calculates the direct runoff from a grid using SCS curve number method and then sum up all of cells with respect to a sub-catchment area belonged to a stream grid and integrated to an outlet. Base flow of a watershed outlet was computed by integrating of the base flow of each stream grid that was averaged the sub-catchment deep-percolation and calculated with the release rate. Two kind of water budget equation were used to compute the water balance in a grid that was classified into not paddy field and paddy field. One of the two equation is a soil water balance equation to account the soil moisture of the upland, forest and excluding paddy field grid. The other is a paddy water balance equation for the paddy field, calculating the ponding depth, the effective rainfall, the deep percolation and the evapotranspiration.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.109.1-109.1
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• 2011

KEPCO was operating power plants with diesel generators in 49 islands including Baekryeong-Do, and the generation capacity was about 66 MW in 2008. The cost of fuel is increasing by the international oil price inflation and continuous rise of oil price is predicted. For the stabilizing of electric power supply to the separate islands, renewable energy and fuel cell systems were considered. Hydrogen is made using renewable energy such as wind power and solar energy, and then a fuel cell system generates electricity with the stored hydrogen. Though the system efficiency is low, it is treated as the only way to secure the stable electric supply using renewable energy at this present. The analytic hierarchy process was used to select suitable candidate island for the system installation and 5 islands including Ulleung-Do were selected. Economic evaluation for the system composed of a kerosene generator, a wind power, an electrolysis, and a fuel cell system was conducted with levelized generation cost based on present value methode. As the result, the necessity of renewable energy combined generation system and micro grid composition in the candidated islands was confirmed. Henceforth, the development of an integration technology which connects micro grid to the total power grid will be needed.

• 전력전자학회논문지
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• 제25권4호
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• pp.293-302
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• 2020

This study proposes a triple-loop current control method for the auxiliary power unit of fuel cell trains. The auxiliary power unit of fuel cell trains has a grid-connected function when power is supplied to the utility grid. Moreover, the auxiliary power unit of trains has a 1500 V DC link voltage; thus, PWM frequency cannot be increased to a high frequency. Owing to this low PWM frequency condition, creating a triple-loop design is difficult. In this study, a triple-loop controller is developed for a capacitor voltage controller in standalone mode that operates as an auxiliary power supply for trains and for a grid current controller in grid control mode with an inner capacitor voltage controller. The voltage controller employs an inductor current controller inner loop. To overcome low PWM frequency, a design method for the bandwidth of the capacitor voltage controller considering the bandwidth of the inner inductor current controller is described. The effectiveness of the proposed method is proven using PSIM simulation.

• 한국지리정보학회지
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• 제19권3호
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• pp.127-143
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• 2016

본 연구는 상이한 셀 크기에 따라 밀도구분적 인구추정의 정확성이 어떻게 변화하는지를 탐색하였다. 미국 조지아주 풀턴 카운티를 사례로 한 밀도구분적 인구 지도가 지능적인 밀도구분적 지도제작기법, 인구자료, 원본 및 모의된 토지이용 및 피복 자료를 이용하여 30m에서 420m의 해상도까지 매 30m 간격으로 생성되었다. 밀도구분적 인구 지도의 정확성은 RMSE 및 수정 RMSE 통계치를 이용하여 평가되었다. 프랙털 차원 값은 TPSA 방법을 사용하면서 30m에서 420m의 해상도까지 생성된 밀도구분적 인구 지도에 대해 각각 계산되었다. 연구결과에 따르면, 속성의 정확성 측면에서 인구를 보다 정확하게 추정하기 위해서 210m 이하의 격자 셀 크기가 적절하였나, 사례지역에서 밀도구분적 인구추정의 허용가능한 공간적 정확성을 충족시키기 위해 30m의 격자 셀 크기가 적절하였다. 또한, 프랙털 분석은 120m의 격자 셀 크기가 사례지역에서 밀도구분적 인구추정을 위한 최적의 해상도 이다는 것을 보여준다.