• 한국전기화학회:학술대회논문집
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• 2004.06a
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• pp.95-98
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• 2004

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1987.11a
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• pp.75-78
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• 1987

저어널베어링으로 지지되고 있는 축 및 베어링 시스템에서 축이 고속으로 회전할 때, 어느 회전수 이상에서 시스템의 안정성이 깨어져 축의 진동진폭이 갑자기 커지는 Self-excited whirl이라 불리우는 불안정 현상이 존재한다. 따라서 고속회전체에 적용되는 공기윤활 저어널베어링에 있어서 안정성 문제는 설계 및 운전에 고려되어야 하는 지배적 요인 중의 하나가 된다. Lund, Fleming과 Cunningham, Mori 들은 외부가압형 공기윤활 저어널베어링의 안정성을 이론적으로 해석하였으며 Pincus는 Self-acting형 공기베어링에서 편심율이 작은 경우 2-Lobe 베어링이나 3-Lobe 베어링이 원형베어링보다 강성도와 감쇠력이 더 크므로 안정성이 더 좋을 것이라고 정성적으로 예측했다. 그러나 외부가압 공기윤활 저어널베어링의 안정성에 비원형 베어링의 유효성은 김 두환, 김 금모, 박 종포 등에 의하여 실험적으로 제시되었다. 따라서 본 연구는 외부가압형 공기윤활 저어널베어링에서 Multi-lobe 형상의 베어링이 축 및 베어링 스스템의 안정성에 미치는 효과를 원형의 경우와 비교하여 이론적으로 해석하여 Multi-lobe베어링의 유효성을 보이고 이에 적용 가능한 Programing을 하여 몇가지 경우에 대하여 계산을 하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.11
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• pp.1605-1612
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• 2002

Thermodynamic performance analysis has been carried out for a hybrid electric power generation system combining a gas turbine and a solid oxide fuel cell and operating at over-atmospheric pressure. Performance characteristics with respect to main design parameters such as maximum temperature and pressure ratio are examined in detail. Effects of other important design parameters are investigated including fuel cell internal parameters such as fuel utilization factor, steam/carbon ratio and current density, and system parameters such as recuperator efficiency and compressor inlet temperature.

• The KSFM Journal of Fluid Machinery
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• v.11 no.1
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• pp.33-39
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• 2008

Hybrid power generation systems combining a solid oxide fuel cell and a gas turbine is promising due to their high efficiency. In the pressurized hybrid system, the operating condition of the gas turbine may play a critical role in designing the hybrid system. In particular, prevention of surge of the compressor can be a critical issue. The existence of fuel cell between the compressor and the turbine may cause an additional pressure loss and thus compressor operating points tend to approach the surge if the original turbine inlet temperature is pursued. In this study, bypassing some of the turbine inlet gas directly to the turbine exit side is simulated. Its effects on suppressing the surge problem and change in performance characteristics are discussed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.2 s.257
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• pp.125-131
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• 2007

This paper presents guideline for a practical design of the hybrid system combining a pressurized solid oxide fuel cell and a gas turbine. Design of the hybrid system based on a virtually designed gas turbine was simulated using models for off-design operation of the gas turbine. Two system configurations, with different method for supplying reforming steam, are considered and their design characteristics are compared. A higher design cell temperature provides better system performance. However, there exists a maximum allowable design cell temperature because the operating point of the compressor approaches the surge point with increasing fuel cell temperature. Increased pressure loss at the fuel cell moves the compressor operating point toward the surge point and reduces system performance.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.7
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• pp.615-622
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• 2004

Recently, the hybrid system combining fuel cell and gas turbine has drawn much attention owing to its high efficiency and ultra low emission. It is now on the verge of world wide development and various system configurations have been proposed. A national project funded by Korean government has also been initiated to develop a pressurized hybrid system. This work aims at presenting design performance analysis for various possible system configurations as an initial step for the system development. Study focuses are given to major design options including the power ratio between gas turbine and fuel cell, reforming method (internal or external), reforming heat source (reforming burner, cathode hot air, fuel cell heat release) and steam supply method for reformer (anode gas recirculation, external steam generator). A wide variation in performance among different configurations has been predicted.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.149-152
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• 2012

This paper describes the study of integrated hydrogen supply system for environment friendly propulsion systems of fuel-cell UAV. Diluted hydrochloric acid was used for direct-decomposing solid-state $NaBH_4$ and generating hydrogen. Self-hydrogen pressurized reactor and pressure regulator was introduced for stable hydrogen supply. Prototype of integrated hydrogen supply systems using the solid-state $NaBH_4$ direct-decomposition was designed for performance evaluation and concept demonstration.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.11a
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• pp.310-313
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• 2011

국내에서 고층건물의 제연시스템으로 급기가압 제연시스템이 일반적으로 사용되고 있는데, 기존의 급기가압 제연시스템의 설계방안과 같이 한개의 급기풍도를 통해 누설량과 보충량이 동시에 공급될 경우에는 부속실과 옥내간에 형성되는 차압이 설계기준에 미달하거나 과압이 될 가능성이 매우 높아져서 급기가압 제연시스템의 설치목적을 달성하지 못할 수 있다. 이에 대한 개선방안으로 본 연구에서는 누설량의 공급과 보충량의 공급을 각기 다른 유로를 통해 수행하는 방안 및 장치구성을 제시함으로서 고층건물에서 화재 발생시 안전한 피난환경을 제공하고자 한다.

• Electrical & Electronic Materials
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• v.7 no.1
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• pp.64-72
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• 1994

본 고는 현재 전기적 응용을 위한 수지 절연물의 진공/가압 수지-주형처리 분야에서 가장 앞선 기술과 연구개발력을 보유하고 있는 스위스의 Ciba-Geigy사와 최신의 진공성형 시스템을 개발, 생산하고 있는 독일의 Hedrich사 및 진공주형/자동가압 성형장비를 생산하는 스위스의 Vogel사 등을 최근에 방문하여 Epoxy, Polyurethane, Polyester 및 Silicone 수지 등의 수지절연시스템을 가지고 구조적으로 기포가 없으며 전기적, 기계적, 열적특성이 매우 우수하고 매끄러운 표면이 요구되는 수지 mold제품을 생산하는데 적용되고 있는 진공 수지-주형처리기술의 현황과 아울러 경화시간을 크게 단축시켜 생산자동화가 가능한 최신의 자동가압겔화(Automatic pressure gelation)/주입몰드공정(Injection molding process)의 특징 및 기술개발현황에 대해 파악한 내용을 소개하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.9
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• pp.652-658
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• 2008

Design performances of the fuel cell / gas turbine hybrid power generation systems based on two different fuel cells (PEMFC, SOFC) have been comparatively analyzed. In each system, the fuel cell operates at an elevated pressure corresponding to the compressed air pressure of the gas turbine. Both internally and externally reformed systems were analyzed for the SOFC hybrid system. Component design parameters of 10kW class small systems are assumed. For all hybrid systems, increasing the turbine inlet temperature increases the power portion of the gas turbine. With increasing the turbine inlet temperature, system efficiency decreases in the PEMFC system and the internally reformed SOFC system while that of the externally reformed SOFC system increases slightly. The internally reformed SOFC hybrid system is predicted to exhibit the best system efficiency.