• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.5
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• pp.955-961
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• 2009

Present, a portable battery have problem that the volume increases according to capacity Increase. Direct Methanol Fuel Cell is alternative by solution plan of this problem. In this paper, the characteristics of DMFC are analyzed by change in concentration and discharge of fuel in natural convection and room temperature condition. According to the analysis result, polarization by delay of diffusion velocity of hydrogen ion appeared in methanol of low concentration. And if have a lot of supplies of methanol, generation power declines by electric cell cooling effect.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.245-246
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• 2012

ITER 초전도자석 전원공급장치의 예비설계가 실제 크기 6펄스 R&D 컨버터의 제작 및 시험결과를 기반으로 수행되었다. ITER 컨버터는 자체적으로 지지되는 알루미늄 버스바 구조로 제작되며, 이 버스바에 양면 클램핑 방식으로 조립되는 Thyristor 스위치는 4인치 규격으로써 컨버터의 종류에 따라 한 개의 암 당 8 - 16 개의 소자가 병렬로 구성된다. ITER 컨버터 예비설계는 알루미늄 버스바 구조설계, 컨버터 냉각설계, 컨버터 전기회로 설계, 컨버터 고장해석 및 보호설계, 시험절차 및 요건 등을 포함하며, 본 논문에서 그 설계결과를 기술한다. ITER 컨버터는 예비설계 결과를 기반으로 상세설계 및 제작설계를 거친 후 제작된다.

• Korean Journal of Veterinary Service
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• v.40 no.4
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• pp.245-251
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• 2017

Cold air or ice water are used to chill poultry carcasses after slaughter. In order to compare the microbial reduction effect of two different chilling systems in poultry carcasses, Pre-and post-chilled carcass samples were tested for contamination agents such as aerobic bacteria counts, E. coli counts and Salmonella spp. counts. Water chilling system showed higher reduction ratio of bacteria than air chilling system during the three seasons. Also, aging of slaughter facility was related with bacterial contamination of pre-chilld carcasses. And additional volatile basic nitrogen (VBN) test were conducted in poultry packing meats and it increased steadily during 15 days. VBN at 8~9 days were over 13 mg% with putrid smell. Poultry packing meats by water chilling system were fresher than air chilling system during early storage time. But those decayed faster after 9 days.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.395-399
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• 2009

Advanced afterburner used in the most modernized gas turbine has new designing paradigm to cope with reinforced power density. The most distinct change is the designing trend to integrate fuel injectors and flame holder in order to manage higher temperature of inlet air. F414 and F110-GE-132 engine adopted this methodology and installed a variable nozzle utilizing CMC(Ceramic Matric Composite) material and active cooling of nozzle flap with ejector nozzle in order to enhance the life cycle of engine components and an economical aspect. These technological trends can be utilized for an advanced ramjet engine and combined cycle engine like TBCC.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.97-100
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• 2009

Cold flow and ignition tests were performed for a technology demonstration model of a 75-tonf thrust chamber which is a candidate liquid rocket engine for a next Korea Space Launch Vehicle. The test facility was modified to support the new concepts of the thrust chamber such as ignition system, film cooling and LOx leading supply. The hydrodynamic characteristics of the supply pipelines, thrust chamber and igniter as well as the filling time of the propellants were obtained through the cold flow tests on the LOx and kerosene and the ignition cyclogram was determined using the results. The ignition test was successfully accomplished according to the cyclogram and therefore, a basic information was obtained for further hot firing tests.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.129-132
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• 2003

Used cutting fluid from machining processes is harmful to both environment and human health. Chemical substances that provide the lubrication function in the machining process are toxtc to the environment if the cutting fluid is released to soil and water and caused serious health problems to workers who are exposed to the cutting fluid in both liquid and mist form. Recently. cost of using cutting fluid is increasing as the number and the extensiveness of environmental protection laws and regulations increase. Therefore, the use of cutting fluid in machining processes place an enormous burden on manufacturing companies to cover the additional costs associated with their use and protection of our environment. Current trends in manufacturing are focused on minimizing or eliminating the use of metalworking fluids in machining processes. And the increased costs for the disposal of waste products (swarf, coolants and lubricants), especially in industrially developed countries, has generated interest in dry machining. A variety of new techniques are testimony that new technology has rationalized further efforts to research and implement dry machining processes. This paper presents the developed equipment, the process optimization and the applications in the field of surface grinding for the new cryogenic dry machining using a compressed cooling air. The investigated new machining process method shows many advantages compared to conventional techniques with cutting fluid.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.4
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• pp.7-12
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• 2010

We have developed a SPICE compatible model of thermoelectric devices, and a parameter extracting technique only by electrical and temperature measurement by using Harman method was proposed. The proposed model and parameter extraction technique do not require experimental data from thermal conductivity measurements. The maximum error between extracted parameters extracted by proposed method and conventional method was about 14%, which is not a severe mismatch for real application. The proposed model is applicable to design of both for thermoelectric coolers and thermo electric generators.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.250-250
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• 2011

지정학적으로 3면이 바다로 접하고 있는 우리나라 해안가 주변의 원자력발전소는 관류형 냉각 방식(Once-through cooling System)을 채택하고 있기에, 이 계통을 통과한 냉각수는 주변해역으로 흘러들어가 주변 환경에 영향을 줄 수 있다. 또한 동해 주변 인접국들의 활발한 원자력 이용과 방사능 물질의 수송 등으로 인해 방사능 사고 위험이 증대됨에 따라 동해 원전 주변의 해양방사성물질 거동에 대한 필요성이 제기되고 있다. 이에 따라 동해의 해양환경을 조사 분석하여 해역에서의 오염 물질의 거동 파악이 중요하고, 산업시설 주변 연안의 오염물 이동 및 해석을 위해 오염물의 시 공간적으로 농도를 추정하는 것이 중요한 사항이다. 따라서 본 연구에서 수직 수평적으로 2차원 및 3차원화가 용이한 EFDC 모델을 사용하였다. 국립해양조사원에서 발간하는 DC103의 수치해도를 이용하여 모델영역은 동서방향으로 171km, 남북방향으로 235km로 설정하고, 격자간격은 $1km{\times}1km$의 정방향 격자를 사용하여 동해 월성 주변의 조위 시계열 검증 및 조화분석을 통한 검증을 실시한 결과 관측한 결과와 양호한 재현성을 나타내었다. 또한 국립수산과학원에서 제공되고 있는 년별 수온, 염분 자료 등의 해양환경과 지형적 특성을 고려하여 오염 물질의 이동 경로를 파악함으로써 사고시 피해를 줄이고자 한다.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.07a
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• pp.182-187
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• 2002

국내 저온저장고의 주류를 이루고 있는 컨테이너 박스형 저온저장고의 문제점은 재래식 제어방식으로 인한 성능저하 외에도 자체 구조적인 설계상의 문제점을 가지고 있다 이러한 구조적인 문제점을 열거하면 다음과 같다. 첫째, 한 축 방향에 설치되어있는 유니트 쿨러에서 토출되는 냉기에 의해 저장고 내의 공기를 냉각하는 형태이기 때문에 냉기의 분포가 고르지 못하여 균일한 온도 분포를 이루기 어렵다는 단점을 가지고있다. 둘째, 한 축 방향에서 토출되는 냉기가 맞은 편 벽면까지 도달해야 하기 때문에 풍속이 강해야 하며 이로 인해 저장 청과물이 냉해를 쉽게 입고 심한 증산작용에 의해 쉽게 표면건조나 중량감소를 가져온다. 셋째, 천장부와 측벽부가 90$^{\circ}$의 경사각을 가지고 있어 공기의 유동이 원활하지 못하여 에디현상으로 인한 온도나 풍속의 불균일 구간을 피해서 청과물을 저장해야 하기 때문에 그만큼 버려지는 공간이 많아 비경제적이다. 넷째, 위와 같은 문제점들 때문에 중ㆍ대형의 저온저장고를 컨테이너 박스형으로 설비 할 경우 보다 심한 온도 불균일과 냉기유동 분포를 보여 경제적인 손실이 더 커지게 되는 악순환을 낳게된다. 이에 따라 본 연구에서는 국내 저온저장고의 구조적인 설계상의 문제점을 인식하고 이를 해결하고자 3차원 CFD 시뮬레이션을 이용하여 저온저장고의 새로운 모델을 설계하였다. 이론 바탕으로 직접 저온저장고의 시작기를 개발하여 저장고 내부의 역 유동과 난류유통을 해석하였다. (중략)

• Corrosion Science and Technology
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• v.9 no.5
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• pp.216-222
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• 2010

Most of the thirteen substations in operation in the metropolitan area were installed around the year 2000, and since water cooling methods are used to directly withdraw heat from transformer oils, a stable supply of electric power is required through optimal maintenance of facilities. The water cooling tower installed outdoors, which uses the water supply as sprinkler water, experiences the most problems. Since more than 90% of the cooling water is reused, the dissolved composition in the water becomes concentrated due to long operating hours, and impurities dissolve in the water due to air flowing in from the outside, forming hard scales on the outer surface of the cooling tube, and in extreme cases, reacting with the tube material composition, leading to corrosion. As a result, not only is cooling efficiency lowered, but in extreme cases the cooling tube must be replaced. In this study, the characteristics and composition of the scales formed on the cooling tube were analyzed and corrosion characteristics of material types were identified in order to find an efficient maintenance method for cooling tubes. In addition, the degree of dissolution of various chemicals were investigated during the removal of scales that have been formed.