• 산업경영시스템학회지
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• 제20권43호
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• pp.365-379
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• 1997

Currently the problem of air pollution caused by the motor vehicle emission is of the most serious problems to be solved. Life Cycle Assessment is a process to evaluate the environmental burdens associated with a product or process by identifying and quantifying energy and materials used and wasters to the environment. This paper establishes a Life Cycle Assessment Systems which satisfies the criteria motor vehicle emission for the automobile producers who are currently producing the automobiles with catalytic convert. This plan also considered the constraint of the effective motor vehicle emission by way of the exhaust gas recirculation, electronic fuel injection, closed loop carburetor. In order to develope the performance of the LCA systems, the recent emissions test data have also been applied. The result of the development LCA systems has proved that the LCA plans presented in this paper satisfies the criteria motor vehicle emission and will be contributed to constrain the motor vehicle emission most effectively.

• 한국산학기술학회논문지
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• 제21권1호
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• pp.190-196
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• 2020

체계의 신뢰도 향상을 위한 활동으로 고장 보고, 분석 및 고장 수리체계 (FRACAS: Failure Reporting, Analysis and Corrective Action System)가 다양한 산업 분야에서 적용되고 있다. FRACAS는 식별된 고장에 대한 원인 분석과 적절한 시정 조치, 결과 검증을 반복 수행하는 활동으로 신뢰도 향상에 효과적이지만, 기존의 개발 환경에 통합 운용하기에는 프로세스, 데이터 수집 및 관리 등 여러 가지 측면에서 제약사항이 있다. 국내 방산분야에서는 FRACAS 적용의 어려움을 해소하기 위해서 FRACAS 시스템 개발 및 프로세스 개선에 관한 연구가 진행되었지만, 대부분이 운용/유지 단계에 집중되어 있다. FRACAS는 총 수명주기 체계관리(TLCSM: Total Life Cycle System Management) 관점에서 운용되어야 하므로, 개발 초기인 설계 단계부터 FRACAS를 적용할 수 있도록 참조 아키텍처에 대한 연구가 필요하다. 본 논문에서는 국방 무기체계의 전 수명주기에 걸쳐 FRACAS를 효과적으로 적용하기 위해, 체계 수명주기 단계와 FRACAS Closed-Loop 프로세스, FRACAS 필수 요소 등을 고려한 TLCSM 기반의 통합 아키텍처 구축에 대해 연구하였다. 제시된 아키텍처는 함정 전투체계 사업에서 FRACAS 수행 시 참조 모델로 활용하였다.

• 한국추진공학회지
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• 제24권5호
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• pp.21-33
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• 2020

본 연구에서는 액체 수소를 연료로 사용하는 팽창기 사이클 로켓 엔진의 시스템 해석을 위한 프로그램을 개발하였다. 수소의 물성치는 온도에 따른 이성질체의 비율을 고려하였다. 팽창기 사이클 엔진의 개방형과 폐쇄형 형식에 따른 해석 절차를 수립하고 부품별 해석 방법을 제시하였다. 본 해석 프로그램의 검증을 위해 팽창기 사이클 엔진인 Vinci와 SE-21D를 대상으로 엔진 작동점의 성능 및 국외에서 수행된 해석 결과와 비교하였다. 해석 결과, 입력 정보가 부정확한 일부를 제외한 추진제의 질유량, 비추력, 동력과 같은 시스템의 주요 성능 인자는 1~2% 내외의 오차로 높은 정확도를 나타내었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2206-2210
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• 2007

As a power transmission line supplying power to a densely populated city, the high temperature superconducting (HTS) cable is expected to one of the most effective cables with a compact size because of its high current density. The verification of HTS power cable system have been progressed by KEPRI. A cooling system for a 3-phase 100m HTS power cable with 22.9kV/1.25kA was installed and tested at KEPCO's Gochang power testing center in Korea. The system consists of a liquid nitrogen decompression cooling system with a cooling capacity of 3kW and a closed circulation system of subcooled liquid nitrogen. Several performance tests of the cable system with respect to the cooling such as cooling capacity, heat load and temperature stability, were performed at several temperatures. Thermal cycle test, cool-down to liquid nitrogen temperature and warm-up to room temperature, was also performed to investigate thermal cycle influences. The outline of the installed cooling system and performance test results are presented in this paper.

• 한국수소및신에너지학회논문집
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• 제30권4호
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• pp.347-355
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• 2019

As a solution to the growing concern on the global warming, researches are being actively carried out to apply carbon dioxide capture and storage technology to power generation systems. In this study, the integrated gasification combined cycle (IGCC) adopting oxy-combustion carbon capture was modeled and the effect of replacing the conventional air separation unit (ASU) with the ion transport membrane (ITM) on the net system efficiency was analyzed. The ITM-based system was predicted to consume less net auxiliary power owing to an additional nitrogen expander. Even with a regular pressure ratio which is 21, the ITM-based system would provide a higher net efficiency than the optimized ASU-based system which should be designed with a very high pressure ratio around 90. The optimal net efficiency of the ITM-based system is more than 3% higher than that of the ASU-based system. The influence of the operating pressure and temperature of the ITM on system efficiency was predicted to be marginal.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 1999년도 제1회 학술대회논문집(KIASC 1st conference 99)
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• pp.1-6
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• 1999

The recent progress in the new cooling technology for superconducting systems without liquid cryogens is briefly presented. In these conduction-cooled systems, the super-conducting magnets are cooled by a direct contact with closed-cycle cryocoolers and only electricity is supplied to maintain the cryogenic temperatures. It is reported that at least 20 conduction-cooled (low Tc or high Tc) super- conducting systems have been constructed, tested, or commercially used worldwide. Some of the significant design issues are discussed in comparison with the conventional liquid-helium cooled systems.

• International Journal of Air-Conditioning and Refrigeration
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• 제12권4호
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• pp.206-213
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• 2004

Cycle test for developed phase change material (PCM) is necessary in order to assess the variation of latent heat, which decreases with time by deterioration. T-history method and measurement using heat-flux meter are appropriate for the cycle test in a tube filled with PCM because they do not need an extraction of sample in measuring heat of fusion. In the present study, these methods were applied to a PCM having a melting point below a room temperature, different to the past studies for PCMs melting above a room temperature. As a result of experiment using pure water as specimen, we can obtained rea-sonable values for heat of fusion.

• International Journal of Precision Engineering and Manufacturing
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• 제2권4호
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• pp.54-60
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• 2001

This paper deals with control design method having anticipation delay which is proposed for the discrete nonlinear engine where system dynamics is not accurate. Due to the induction-to-power delay in internal combustion(IC) engine having abrupt torque loss, underdamping and chattering in engine idle speed becomes a serious problem and it could make drivers uncomfortable. For this reason, Three types of the closed-loop controller are developed for the stable engine idle speed control. The inputs of the controllers are an engine idle speed and air conditioning signal. The output of the controllers is an duty cycle to operate the idle speed control valve(ISCV). The proposed controllers will be useful for improving actual vehicles since these shows good test

• 한국의사학회지
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• 제26권1호
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• pp.1-7
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• 2013

Jeonuigam(典醫監) is one of the Big Three of medical government office through the Joseon dynasty era. But Jeonuigam literature is extremely rare. This paper is to analyze 362 cadets of "Jeonham-saengdoan(前銜生徒案)" by writer of Jeonuigam origin. Jeonuigam filled cadet on a three-year cycle because the national examination for medical officials is conducted on same cycle. Most cadets came from a few meritorious family of medical career officials. Ratio of ten major family stand at 34.91 percent. 373 of the 392 cadets are confirmed as family member of medical bureaucrat. They have a very closed society. Wancheon(完薦) and cadet system strengthen the monopholy power of a few family. The analysis of study confirmed that in the 19th century Joseon(朝鮮) dynasty had monopolized the medical technicians.

• 에너지공학
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• 제13권4호
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• pp.296-300
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• 2004

본 연구는 지열원 물 대 물(water to water)히트 펌프 시스템의 냉방 및 난방 운전시 성능 특성과 경제성 평가에 관한 것이다. 5개의 보어홀당 지중 100m의 깊이로 밀폐 수직형 지중 열교환기(closed-vertical ground source)가 설치된 냉난방 시스템이 적용된 건축물에 대하여 냉난방 운전성능을 평가하였으며, 연간 소비전력을 측정하여 실제 시스템의 경제성을 분석하였다. 또한, 순환수의 입구온도에 따른 시스템의 운전 성능을 분석한 결과 난방시에는 COP가 3.0에서 4.2로 증가한 반면, 냉방시에는 5.0에서 3.7로 감소하였다. 본 실험을 통해서,대상 건축물에 대한 지열 냉난방 시스템의 수명주기비용은 기존 냉난방 시스템(보일러+에어컨)에 비해서 68%까지 절감되었으며, 시스템의 경제성을 고려해 볼 때 기존 건축물에도 지열원 냉난방 시스템을 적용하는 것이 타당하다.