• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.2
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• pp.117-124
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• 1993

This study is concerned with an application of the boundary element method on the crack problem. The stable and efficient analysis method of two dimensional elastostatic stress intensity factor on the mode I deformations is established from the result o stress analysis for the center cracked plates. In order to precisely analyse, The subelements of quadratic element, singular elements on the crack tip and interface and division into regions are applied to elastic stress. The usefulness of the method has been tested with a center cracked plates, a double edge cracked plate and a single edge cracked plate, and the results have turned out to be fairly satisfactory.

• Journal of the korean Society of Automotive Engineers
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• v.8 no.1
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• pp.29-39
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• 1986

The purpose of this study is to develop an exhaust gas recirculation valve for reduction of the NOx emission of the gasoline engine. In this study the back pressure modulated(BPM) EGR system was developed and tested for the 1.6$\ell$ gasoline engine. By this system 50% of NOx emission was reduced at 7% EGR rate. Fuel consumption and CO emission were not affected by EGR but HC was increased up to the level of allowable limit. Overall operation was satisfactory. As a result of this study, the technics for developing EGR valve and adjusting the engine for EGR have been established.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.8
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• pp.1398-1406
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• 2008

This paper describes the electrical breakdown characteristics of broken toughened glass stem insulators by comparing with those of sound ones. The broken toughened glass stem insulators were taken from the electric railway field. According to the international standards, the sound and broken toughened glass stem insulators were tested in electrical strength. In the test, the power frequency voltage and the impulse voltage with a standard waveform were applied to the insulators. The power frequency voltage tests were carried out under both dry and wet condition and the impulse voltage tests under only dry condition. The acquired results were compared one another and discussed in electrical breakdown characteristic by analyzing the flashover progress pictures. As a result, the electrical strength of the broken toughened glass insulators was acquired and the processes of the surface breakdown on the toughened glass insulators were confirmed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.7
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• pp.69-74
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• 2014

Recently, IEC published new standards about the requirements and tests for lightning protection system(LPS) components. If components are used for LPS, they should comply with the IEC standards. This paper, we collected six specimens for the metallic connection components using in domestic, and it tested for withstand lightning current which according to the IEC 62561-1. As a result, only one specimen meet this performance requirement. The specimen is the metallic connection component with four bolts fixed. Therefor, when designing of LPS in domestic, the metallic connection components shall be taken into account for the selection of the withstand lightning current. In addition, we need to develop for LPS components product and the national standards.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.388-391
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• 2009

In this paper, We observed spectral responsivity of general poly-cristalline silicon solar cell. This is very important to define solar cell's characteristics. So we tested two small modules that made of poly-cristalline silicon solar cells. We expect to the result of this experiment is useful for researching and measuring solar cell's characteristics.

• Journal of the Korean Society of Safety
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• v.23 no.5
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• pp.79-83
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• 2008

The corrugated stainless steel tubing(CSST) for the fuel gas piping system can be installed easily and quickly. It is often constructed under the ceiling and the wall which has a good flexibility and installation in comparison with iron pipe. However, the quality of the CSST is determined to depend upon the welding skill of stainless steel tubing. In this study, it is tested by controlling jet point of Ar as inert and cooling gas, and also compared with the bead state of welding point and the performance. As a result, it has the best condition when the jet point of Ar is located behind $5{\sim}10mm$ of the welding point.

• Smart Media Journal
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• v.6 no.1
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• pp.39-46
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• 2017

The internet has become an important part of the many aspects of people's daily lives such as work, study, entertainment and in form of electronic commerce, shopping. Electronic commerce is growing rapidly in Kenya. There are many successful business-to-business, business-to-customer and customer-to-customer online shopping companies in Kenya. As a consequence, competition between vendors is intense and, therefore, mitigating the negative effects of high product uncertainty is necessary requirement as it remains a biggest hindrance for success of the online shopping. The purpose of this research is to investigate how online product description, third party product assurance, customer service and website design mitigate the negative impact of high product uncertainty. A questionnaire with 28 items is designed to collect data from online customers. Using multiple regression analysis, the relationship between dependent variable (product uncertainty) and independent variables such as product description, third party assurance, website design and customer service is tested. The result shows that all the independent variables are negatively correlated with dependent variable, which means that product description, third party assurance, website design and customer service can be used by online vendors to lessen the problem of product uncertainty in online markets.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.411-412
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• 2014

In this paper, the switching losses and performances of Silicon Carbide(SiC) and Silicon based on the MOSFETs have been compared. To do this experiment, the buck converter using both SiC and Si devices have been built and tested. As a result, it has been confirmed that the converter with SiC devices shows better efficiency and performance compared with the converter using Si devices.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.95-100
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• 2002

Detecting simple shaped buildings from 1m-resolution satellite imagery is presented. The proposed algorithm is that first, image features such as edges are detected and then segmentation process is performed with the detected features. It can be result in line primitives. These primitives are linked and grouped by building hypotheses. Proposed building hypotheses restrict a building to simple rectangular shape. And sub-region homogeneity test is performed for finding rooftops of buildings. The proposed algorithm has been tested on IKONOS satellite image with 1m-resolution.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1165-1167
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• 2003

Geometric corrections are required to compensate skew effects, earth rotation effects and so on. Parameters for geometric modeling can be acquired from the metadata information. These parameters allow to locate on ground every pixel of acquired images. In this paper, we tested the precision of geometric modeling of linear pushbroom images, acquired by SPOT 3 and 5 using the satellite orbit information itself without additional external data. The result acquired from examination to recovery the geometry of image using 30 GCPs have about 650m RMSE in SPOT 3 and about 170m RMSE in SPOT 5.