• Transactions of the Korean hydrogen and new energy society
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• v.32 no.4
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• pp.245-255
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• 2021

Various studies about metallic bipolar plates have been conducted to improve fuel cell performance through flow field design optimization. These research works have been mainly focused on fuel cells for vehicle, but not fuel cells for building. In order to reduce the price and volume of fuel cell stacks for building, it is necessary to apply a metallic flow field, In this study, for a metallic flow field applied to a fuel cell for building, the effect of a change in the flow field shape on the performance of a polymer electrolyte membrane fuel cell was confirmed using a model and experiments with a down-sizing single cell. As a result, the flow field using a metal foam outperforms the channel type flow field because it has higher internal differential pressure and higher reactants velocity in gas diffusion layer, resulting in higher water removal and higher oxygen concentration in the catalyst layer than the channel type flow field. This study is expected to contribute to providing basic data for selecting the optimal flow field for the full stack of polymer electrolyte membrane fuel cells for buildings.

• Journal of the Korean Institute of Landscape Architecture
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• v.38 no.2
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• pp.109-118
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• 2010

This study aims to propose practical strategies for the new urban ideal of regeneration. A book review highlights the emergence of new trends of urbanization in knowledge-information industrial society beyond the new town Ideal of the industrial society. The meaning of ‘landscape’ in landscape urbanism represents not the visual and decorative pictures, but the dynamic process in the context of changes and evolutions. Also, knowledge-information industrial society and landscape have a meaning in the same context of flow and process with changes of velocity. Finally, these key words convey a meaning with the new urban trends of urbanization in knowledge-information industrial society in the context of value-oriented characteristics of dynamics and process. Urban regeneration is emerging as the new urban ideal in the knowledge-information industrial society, beyond the new town ideal of industrial society. It is in the same context as landscape urbanism with respect to green infrastructure buildings and designs for the transformation of urban surfaces covered with concrete and asphalt into the ecological surface, and of the ecological surfaces into the cultural surface that could be communicated with human beings. This research revealed the six strategies for urban regeneration as follows. The First, the strategies for the transformation of urban surfaces into ecological surfaces, the second, the strategies for the transformation of ecological surfaces into cultural surfaces, the third, the introduction of mixed and convergence land use, the forth, the transformation of former sites(e.g. military and factory) into urban parks, the fifth, the introduction of waterfront park zones that have the function of ecological and park-oriented mixed land use and, the sixth, the building and design of green infrastructure in the residential and commercial complex in CBD. These strategies call for the reforms of development laws and regulations to restrict building coverage ratio, building heights, and the introduction of park-oriented mixed zoning regulations. Another method for implementating the above listed strategies was the introduction of a strategic planning system instead of the traditional master plan system. This system uses a value planning approach and brand making by imagery. It is able to construct the meaning of an image and its creativeness directly.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.3647-3653
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• 2010

An experimental investigation of the flame appearance and heat transfer characteristics in both unexcited and excited impinging inverse diffusion flames with a loud speaker has been performed. The flame is found to become broader and shorter (in length) with acoustic excitation. The heat flux at the stagnation point is increased with the acoustic excitation. The acoustic excitation is more effective in lean conditions than in rich conditions. The reasons for these behaviors are that acoustic excitation improves the entrainment of surrounding air into the jet. From this study, it is found that the maximum increase of 57% in the total heat flux is obtained at the stagnation point of $\Phi$=0.8. Therefore, it is ascertained that the excitation combustion can be adopted with effective instruments as a method for improving heat transfer in impinging jet flames.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.1
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• pp.124-133
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• 2017

In the current lighting market, LEDs that have a high luminous efficiency, a long life and consume less power have emerged as next generation lighting. Owing to various designs and sizes of LEDs, the production process of existing LEDs involves many tasks that require manual labor; hence, the assembly of LEDs necessitates manpower. Because of the use of manpower, the production costs of LEDs increases and production efficiency decreases. Recently, the assembly parts of LEDs have been standardized for minimizing manual labor, and an LED is developed as an LED panel. The automatic assembly system produces LED convergent lighting by assembling two LED panels and one diffusion cover. To increase the production efficiency of the LED convergent lighting module, it is important that the development of a feeder can continuously supply the LED panels is required, and whose design has sufficient stability. The automatic assembly system of the LED convergent lighting module consists of two feeders, which convey LED panels and diffusion covers to a main conveyor, which assembles the lifted panels and covers. In this study, structural analysis and fatigue life for forced loads on the conveyer line of the feeder in the process of lifting LED panels and diffusion covers of each feeder, is analyzed. In addition, the drive of the belt constituting the conveyor line of each feeder is simulated, and the dynamic characteristics of the belt is analyzed using the virtual engineering method.

• Korean Journal of Optics and Photonics
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• v.16 no.1
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• pp.50-55
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• 2005

A method for measuring the wavefront error and the modulation transfer function(MTF) of large aperture optics using an unequal path interferometer is presented. A bidirectional shearing interferometer is used for collimation testing of the measurement system. A large aperture Fizeau interferometer with long optical path difference measures the wavefront error of the optics under test by using a $\Phi$ 400 mm off-axis parabolic mirror. The MTF is also measured at the wavelength of the interferometer by changing the laser light into partially incoherent light. Test results of a $\Phi$ 300 mm Cassegrain type satellite telescope made in Korea are presented.

• Journal of Korea Society of Industrial Information Systems
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• v.20 no.6
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• pp.79-90
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• 2015

Since the late 1990s, the Korea wave has been very big issue among Asian nations. It has been increased in some regions including Russia, East Europe, South America but it has been decreased in some regions including Southeast Asia, Japan and China. The stream of Korea wave has been changed until now. We need a study considering on the time period of Korea wave. So this paper shows several implications from some changes by each time period of Korea wave for Southeast Asia cultural regions. In order to achieve objectives of the paper, we collected and classified 2511 requirements from bulletin board systems and e-mails. It shows how to improve e-service quality and to enhance nation brand utilizing types of requirements of Southeast Asia cultural regions and by the time period of Korea wave using QFD methodology. These implications are applied to design a tourism website for Southeast Asia cultural region.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.5
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• pp.468-475
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• 2012

A proper stacking force and assembly are important to the performance of fuel cell. Improper assembly pressure may lead to leakage of fuels and high interfacial contact resistance, excessive assembly pressure may result in damage to the gas diffusion layer and other components. The pressure distribution of gas diffusion layer is important to make interfacial contact resistance less for stack performance. To analyze the influence of design parameter factors for pressure distribution, and to optimize stack design, DOE (Design of Experiment) was used for polymer electrolyte membrane fuel cell stack pressure test. As commonly known, the higher clamping force improves the fuel cell stack performance. However, non-uniformity of stress distribution is also increased. It shows that optimization between clamping force and stress distribution is needed for well designed structure of fuel cell stack. In this study, stack design optimization method is suggested by using FEM (Finite Element Methode) and DOE for light-weighted fuel cell stack.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.5
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• pp.365-373
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• 2021

In this study, evaporation of LN2 non-spreading pool on concrete plate was dealt with experimentally. The thermophysical properties of concrete, which is a composite material, were obtained by minimizing the difference between the numerical analysis results obtained from the assumed properties and the results from experiments. The thermal energy required for evaporation of the liquid pool is supplied from the concrete plate and the wall of the container. As a result of the measurement, the thermal energy flowing in from the wall was negligible compared to the one supplied from the concrete plate. It was found that the measured evaporation rate of the liquid pool by the heat energy supplied through the concrete plate agrees well with the PTC model except for the initial section of the experiment. The validity of the semi-infinite assumption and the one-dimensional assumption, which are the main conditions of the PTC model, was also verified through experiments. The evaporation rate model in the non-spreading pool discussed in this study can provide a basic frame for the one in the spreading pool, which is a meaningful result considering that the spreading pool is very realistic compared to the non-spreading pool.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.64.3-65
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• 2021

인공지능 기계학습에 의한 한문고전 자동번역기는 승정원일기 뿐만 아니라, 한국 고문헌 중 천문 기록에 특화되어 한자로 된 천문 고전을 한글로 번역해 서비스하고 있다. 한국천문연구원은 한국지능정보사회진흥원이 주관하는 2019년도 Information and Communication Technology 기반 공공서비스 촉진사업에 한국고전번역원과 공동 참여하여 이 자동 번역기 개발을 완료한 것이다. 이 번역기의 개발 목적은 초벌 번역 수준일지라도 문장 형태의 한문을 한글로 자동 번역하는 것이며, 이 연구는 현재 번역기 운용 현황을 서비스 별로 분석하고자 한다. 자동 번역관련 서비스는 크게 3가지이다. 첫째, 누구나 웹 접속을 통해 사용 가능한 한문고전 자동번역 대국민 서비스이다. 1년간 자체 시험을 거쳐 2021년 1월 12일 시험판을 오픈하여 운용 중에 있다. 둘째, 기관별로 구축된 코퍼스와 도메인 특화된 번역 모델 등을 관리할 수 있는 한문고전 자동번역 확산 플랫폼 서비스이다. 대국민 서비스와 함께 클라우드 기반으로 서비스되며, 한국고전번역원이 관리를 담당한다. 셋째, 자동번역 Applied Programmable Interface를 활용한 한국천문연구원 내 자체 활용이 가능한 천문고전 자동번역 서비스이다. 서비스 현황 분석은 기관별 관리 서비스에 해당되는 한문고전 자동번역 확산 플랫폼에서 집계하여 제공하는 대시보드의 통계 기능을 활용한다. 각 서비스별 문장과 파일 번역 이용 건수, 번역 속도, 평균 자수 뿐만 아니라, 번역 모델 프로필에 따른 이용률 분석이 가능하다. 이에 따른 주요 분석 중 하나인 올해 전체 번역 이용 건수는 한 해 각 기관의 평균 방문자수 대비 87% 성과 목표에 해당되는 약 38만 건에 근접할 것으로 예측된다. 이 자동 번역기는 원문 해독 시간을 단축시키는 효과와 함께 미번역 천문 고문헌의 활용성을 높여 다양한 연구에 기여할 것이다.

• Journal of the Korean Wood Science and Technology
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• v.42 no.4
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• pp.407-419
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• 2014

The analysis of shape before and after heating, Surface moisture content, Moisture weight change and surface heat distribution by fixed type microwave heating in forms of flat veneer and veneer roll of Korean pine, pitch pine, larch and yellow poplar was conducted. The results were as follows: In case of flat veneer, the quality after microwave heating was comparatively good, but it was somewhat warped. These phenomena may be due to transformation by nonuniform drying stress and stronger effect of local irradiation on the veneers when heating veneer owing to the characteristics of fixed type microwave equipment. In case of the features of roll-shaped veneer heated by microwave, the quality after heating was comprehensively excellent. Especially there was no warping unlike flat veneer. Heat distribution and diffusion were also very stable for roll-shaped veneer and such heat distribution had much influence on surface moisture content and moisture weight loss. Accordingly, the veneer roll would show sufficient drying efficiency in fixed type microwave equipment through a scrutinized examination on generating power and irradiation time according to species and thickness of veneer.