• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.1069-1072
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• 1998

Recently the development of design and automation technology and manufacturing method, has reduced the cost of chip, but it becomes more difficult to test IC chip because test technique doesn't keep up with these techniques. In case of IC testing, obtaining test vectors to be able to detect good chip or bad one is very important, but according to increasing complexity, it is very complex and difficult. Another problem is that during testing, there could be capability of physical and electrical damage on chip. Also there is difficulty in synchronization between CUT (circuit under test) and Test equipment〔1〕. Because of these difficulties, built in self test has been proposed. Not only obtaining test vectors but also reducing test time becomes hot issues nowadays. This paper presents a new test BIST(built in self test) method. Proposed BIST implementation reduces test time and obtains high fault coverage. By searching internal nodes in which are inserted test_point_cells〔2〕and allocating TPG(test pattern generation) stages, test length becomes much shorter.

• Journal of Hydrogen and New Energy
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• v.21 no.6
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• pp.493-499
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• 2010

Steam reforming (SR) of glycerol, a main by-product of manufacturing process of bio-diesel, for the production of hydrogen was investigated over the Ni-based catalysts. The Ni-based catalysts were prepared by an impregnation method, and characterized by $N_2$ physisorption, CO chemisorption, XRD and TEM techniques. It was found that the Ni/${\gamma}-Al_2O_3$ catalyst showed higher conversion and catalytic stability for the carbon formation than the other catalysts in the steam reforming of glycerol under the tested conditions. The results suggest that the steam reforming of glycerol over modified Ni/${\gamma}-Al_2O_3$ catalyst minimized carbon formation can be applied in hydrogen station for fuel-cell powered vehicles and fuel processor for stationary and portable fuel cells.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.147-149
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• 2005

Synthesis of $TiO_2$ nanoparticle paste is one of the important technologies in dye-sensitized solar cells (DSSC). Performances of the DSSCs from synthesized $TiO_2$ nanoparticle paste was similar or better than those from commercial sources. In addition. cell efficiency was further improved by using large scattering $TiO_2$ particles. Those results was utilized in manufacturing high efficiency DSSC modules.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.3
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• pp.133-140
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• 2007

A 2-D model of fluid flow, mass transport and electrochemistry is analysed to examine the effect of current density at the current collector depending on active layer thickness of catlyst in polymer elecrolyte fuel cells. The finite element method is used to solve the continuity, potential and Maxwell-Stefan equations in the flow channel and gas diffusion electrode regions. For the material behavior of electrode reactions in the active catalyst layers, the agglomerate model is implemented to solve the diffusion-reaction problem. The calculated model results are described and compared with the different thickness of active catalyst layers. The significance of the results is discussed in the viewpoint of the current collecting capabilities as well as mass transportation phenomena, which is inferred that the mass transport of reactants dictates the efficiency of the electrode in the present analysis.

• Journal of the Korean Operations Research and Management Science Society
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• v.31 no.4
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• pp.69-87
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• 2006

This paper proposes an effective approach for the part-machine grouping(PMG) based on the non-binary part-machine incidence matrix in which real manufacturing factors such as the operation sequences with multiple visits to the same machine and production volumes of parts are incorporated and each entry represents actual moves due to different operation sequences. The proposed approach adopts Fuzzy ART neural network to quickly create the Initial part families and their machine cells. A new performance measure to evaluate and compare the goodness of non-binary block diagonal solution is suggested. To enhance the poor solution due to category proliferation inherent to most artificial neural networks, a supplementary procedure reassigning parts and machines is added. To show effectiveness of the proposed approach to large-size PMG problems, a psuedo-replicated clustering procedure is designed. Experimental results with intermediate to large-size data sets show effectiveness of the proposed approach.

• Journal of Korean Institute of Industrial Engineers
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• v.20 no.2
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• pp.51-64
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• 1994

Cellular manufacturing requires formation of machine cells that can produce families of parts with similar processing requirement. The purpose of cell formation is to create separable machine clusters and part families simultaneously. However, the cell formation process often includes the identification of exceptional elements. This paper presents cell formation method under consideration of alternative routings in FMS which consists of machines capable of multi-processing and parts which require more than one operation. We suggest theorems to calculate the maximum number of machine cell and part family which have no exceptional elements. We also develop a cell formation algorithm which is based on the suggested theorem. A numerical example is provided to illustrate the proposed theorem and algorithm.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.83-84
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• 2009

Thin film solar cells based on CIGS continue to be a leading candidate for thin film photovoltaic devices due to their appropriate bandgap, long-term stability, and low-cost production. To date, the most successful technique for the deposition of a CIGS absorber layer has been based on the co-evaporation However, the evaporation process is difficult to scale-up for large-area manufacturing the sputtering and Selenizaton process has been a promising method for low-cost and large-scale production of high quality CIGS In this study, we have used Cu and CuIn alloy targets for precursor deposition the precursor deposited by sputtering Cu and CuIn targets and $CuInSe_2$ thin film is manufactured by Selenization process

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.103.2-103.2
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• 2011

비정질 실리콘 태양전지의 효율을 증가하기 위하여 많이 사용되는 방법 중 하나는 입사되는 빛의 산란을 증가하여 태양전지의 광흡수를 증가시키는 방법이다. 이를 위하여 양극전극으로 사용되는 TCO층의 일정한 패턴 처리를 통하여 광산란을 증가시키는 방법이 사용되고 있다. 본 연구에서는 나노 임프린트 리소그래피방법을 사용하여 Ag 나노로드를 증착한 기판을 제조하고 이를 비정질 실리콘 태양전지에 적용하였다. 실험결과, 그림과 같이 높이와 너비가 300nm 정도로 일정한 패턴의 Ag 나노로드를 제조하였다. 또한, 그 위에 증착된 Si 박막의 경우, 나노로드 전체를 감싸는 돔 형태로 성장하였다. 이와 같은 나노로드 위에 substrate n-i-p 구조의 비정질 박막 태양전지를 증착하고 그 특성변화를 분석하고자 하였다.

• IE interfaces
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• v.11 no.3
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• pp.1-13
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• 1998

This paper addresses a scheduling scheme for Flexible Flow Shop(FFS) in the case that a factory is a sub-plant of an electronic device manufacturing plant. Under this environment, job orders for the sub-plants in the production route are generated together with job processing time bucket when the customer places orders for final product. The processing time bucket for each job is a duration from possible release date to permissible due date. A sub-plant modeled FFS should schedule these jobs orders within time bucket. Viewing a Printed Circuit Board(PCB) assembly line as a FFS, the developed scheme schedules an incoming order along with the orders already placed on the scheduled. The scheme consists of the four steps, 1)assigning operation release date and due date to each work cells in the FFS, 2)job grouping, 3)dispatching and 4)machine allocation. Since the FFS scheduling problem is NP-complete, the logics used are heuristic. Using a real case, we tested the scheme and compared it with the John's algorithm and other dispatching rules.

• Journal of the Korean Operations Research and Management Science Society
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• v.26 no.1
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• pp.71-85
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• 2001

This paper considers a cost model for a U-shaped manufacturing cell formation which incorporates a required number of machines and various material flows together under multi-part multi-cell environment. The model is required to satisfy both the specified operation sequence of each part and the total part demand volume, which are considered to derive material handling cost in U-shaped flow line cells. In the model several cost-incurring factors including set-up for batch change-over, processing time for operations of each part, and machine failures are also considered in association with processing load and capacity of each cell. Moreover, a heuristic for a good machine layout in each cell is newly proposed based on the material handling cost of each alternative sequence layout. These all are put together to present an efficient heuristic for the U-shaped independent-cell formation problem, numerical problems are solved to illustrate the algorithm.