• 한국정밀공학회지
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• 제34권4호
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• pp.287-292
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• 2017

A gas turbine is the main equipment used in a combined heat and power plant. It generates a high sound pressure noise level. To reduce the noise level, an enclosure is installed around the turbine. The sound insulation performance of the enclosure affects the amount of external noise reduction. In this study, a sound transmission loss analysis is performed using the boundary element method to predict sound insulation performance according to the numbers and shapes of the supporter. Radiated noise analysis is also performed for the main external points of the enclosure using ray-acoustics. The results of these analyses are presented and a design plan is proposed that reduces the sound pressure noise level of the enclosure.

• Journal of Advanced Marine Engineering and Technology
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• 제31권4호
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• pp.335-342
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• 2007

A propulsion and lift shafting system in an air cushion vehicle is flexible multi-elements system which consists of two aeroderivative gas turbines with own bevel gears, four stage lift fan reduction gear, two stage propulsion reduction gear air propellers and high capacity of lifting fans. In addition, the system includes the multi-branched shafting with multi-gas turbine engines and thin walled shaft with flexible coupling. Such a branched shafting system has very intricate vibrating characteristics and especially, the thin walled shaft with flexible couplings can lower the torsional natural frequencies of shafting system to the extent that causes a resonance in the range of operating revolution. In this study, to evaluate vibrational characteristics some analytical methods for the propulsion and lift shafting system are studied. The analysis, including natural frequencies and mode shapes, for five operation cases of the system is conducted using ANSYS code with a equivalent mass-elastic model.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.466-471
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• 2004

In gas turbines, excess air for combustion is available and therefore lean premixed combustion is the most promising approach to the significant reduction of thermal NOx emissions. At lean conditions, however, flame stability is inherently worse and hence combustion tends to be incomplete. Efforts have been devoted toward extending the operating range of complete combustion at leaner conditions. One of them is the lean-lean two-stage combustion where lean to ultra-lean secondary mixtures are mixed with the hot burned gas from the primary stage. Conventional flame combustion or flameless reaction are initiated depending on the conditions of the secondary zone. In the first part of the present study, the effects of fuel injection on the emissions and flame stability were investigated for a single tubular flame, In the second part, the emissions and flame stability were studied for a two-stage combustor with secondary mixture injected through the tangential slots on a cylindrical combustor wall. The effects of the ratio of air flow rates to the primary and secondary zones on the emissions and combustion characteristics were investigate.

• 한국분말재료학회지
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• 제26권2호
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• pp.101-106
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• 2019

Ni-based oxide dispersion strengthened (ODS) alloys have a higher usable temperature and better high-temperature mechanical properties than conventional superalloys. They are therefore being explored for applications in various fields such as those of aerospace and gas turbines. In general, ODS alloys are manufactured from alloy powders by mechanical alloying of element powders. However, our research team produces alloy powders in which the $Ni_5Y$ intermetallic phase is formed by an atomizing process. In this study, mechanical alloying was performed using a planetary mill to analyze the milling behavior of Ni-based oxide dispersions strengthened alloy powder in which the $Ni_5Y$ is the intermetallic phase. As the milling time increased, the $Ni_5Y$ intermetallic phase was refined. These results are confirmed by SEM and EPMA analysis on microstructure. In addition, it is confirmed that as the milling increased, the mechanical properties of Ni-based ODS alloy powder improve due to grain refinement by plastic deformation.

• Journal of Advanced Marine Engineering and Technology
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• 제36권5호
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• pp.586-594
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• 2012

미래형 선박 동력장치는 경제성과 친환경성을 같이 요구하고 있다. 즉, 높은 에너지 효율과 함께 대기오염물질 및 온실가스의 배출을 낮추어야 한다. 최근 가스터빈은 효율과 안전성 면에서 많은 기술적 발전을 이룩하였으며 항공용 이외에 파워플랜트의 GT/ST 하이브리드시스템으로 채용의 사례를 넓히고 있다. 본 논문에서는 선박용으로 GT/ST 하이브리드시스템의 가능성을 평가하기 위하여 대용량이 아닌 수십 MW급에 대한 성능 특성을 시뮬레이션으로 검토하였다. 검토된 GT/ST 하이브리드시스템은 최대 효율이 49 %정도이고 TIT에 대하여 최고 효율점을 갖으며 가스터빈과 증기터빈의 부하분담률이 각각 70~75 % 그리고 25~30 % 정도였다.

• Nuclear Engineering and Technology
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• 제41권7호
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• pp.875-884
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• 2009

We present three nuclear/hydrogen-related R&D activities being performed at KAIST: air-ingressed LOCA analysis code development, gas turbine analysis tool development, and hydrogen-production system analysis model development. The ICE numerical technique widely used for the safety analysis of water-reactors is successfully implemented into GAMMA, with which we solve the basic equations for continuity, momentum conservation, energy conservation of the gas mixture, and mass conservation of 6 species (He, N2, O2, CO, CO2, and H2O). GAMMA has been extensively validated using data from 14 test facilities. We developed a tool to predict the characteristics of HTGR helium turbines based on the throughflow calculation with a Newton-Raphson method that overcomes the weakness of the conventional method based on the successive iteration scheme. It is found that the current method reaches stable and quick convergence even under the off-normal condition with the same degree of accuracy. The dynamic equations for the distillation column of HI process are described with 4 material components involved in the HI process: H2O, HI, I2, H2. For the HI process we improved the Neumann model based on the NRTL (Non-Random Two-Liquid) model. The improved Neumann model predicted a total pressure with 8.6% maximum relative deviation from the data and 2.5% mean relative deviation, and liquid-liquid-separation with 9.52% maximum relative deviation from the data.

• 한국연소학회지
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• 제19권3호
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• pp.8-17
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• 2014

The aims of this research were to evaluate effects of biomass co-firing to pulverized coal power plants and the variation of co-firing ratios on the plant efficiency related to power consumption of auxiliary system and flue gas characteristics such as production and component by process simulation based on the existing pulverized coal power plant. In this study, four kinds of biomass are selected as renewable fuel candidates for co-firing: wood pellet(WP), palm kernel shell(PKS), empty fruit bunch(EFB) and walnut shell(WS). Process simulation for various biomass fuels and co-firing ratios was performed using a commercial software. Gas side including combustion system and flue gas treatment system was considering with combination of water and steam side which contains turbines, condenser, feed water heaters and pumps. As a result, walnut shell might be the most suitable as co-firing fuel among four biomass since when 10% of walnut shell was co-fired with 90% of coal on thermal basis, flue gas production and power consumption of auxiliary systems were the smallest than those of other biomass co-firing while net plant efficiency was relatively higher than those of other biomass co-firing. However, with increasing walnut shell co-firing ratios, boiler efficiency and net plant efficiency were expected to decrease rather than coal combustion without biomass co-firing.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2006년도 춘계종합학술대회
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• pp.270-273
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• 2006

본 논문에서는 LabVIEW 기반의 가스터빈 데이터 취득 및 모니터링 시스템을 제안한다. C-Tune DAS로 명명된 실시간 모니터링 시스템은 가스터빈의 유지/보수시 실시간 동작을 분석하는데 중요한 역할을 담당한다. LabVIEW 소프트웨어는 고유 기능별로 데이터 취득부, 데이터 분석 및 표시부, 데이터 저장부로 구성된다. 데이터 취득부를 통해 PMS 서버와 두 대의 cFP로부터 데이터를 취득한다. 복합화력 발전소의 상용 가스터빈에 적용하여 개발된 모니터링 시스템의 타당성을 검증한다.

• 한국가스학회지
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• 제24권1호
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• pp.49-55
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• 2020

산업용 혹은 발전용 가스터빈에 사용되는 이중 콘형 예혼합 연소기의 다단 연소 특성을 이해하기 위하여 실험적연구를 수행하였다. 이를 위하여 기존에 모두 경사면에 공급되는 연료를 콘부분으로 일부 할애하는 방식으로 다단연소 방식을 구성하였으며 콘에서 분사되는 연료공급은 축방향과 콘 경사면 방향으로 하였다. 다단연소 연소특성을 이해하기 위하여 콘에서의 연료 분사 방향과 연료 분배율 변화에 대한 NOx와 CO의 배출 농도 그리고 벽면 온도분포를 측정하였다. 그 결과 총 연료에 대한 콘으로의 분배율이 3%인 경우 콘에서의 연료 분사방향에 관계없이 노즐내의 예혼합 영역에서 연료가 공기와 균일하게 혼합됨으로서 연소영역의 고온점 감소에 의하여 NOx 배출 농도가 감소된다. 그러나 콘에서 축방향으로 분사되는 연료분배율이 8%로 증가하는 경우 노즐 내부 예혼합 영역으로의 화염 역화로 인하여 NOx의 배출농도가 오히려 증가하게 된다.

• 한국가스학회지
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• 제24권4호
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• pp.25-31
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• 2020

산업용 혹은 발전용 가스터빈에 사용되는 이중 콘형 예혼합 연소기의 연소 특성을 이해하기 위하여 실험적 연구를 수행하였다. 노즐의 여러 연료 분사 방식에 대하여 NOx와 CO의 배출 특성, 화염 안정성 및 연소실 온도 분포에 대한 연소특성을 비교하였다. 주 연구 결과로는 연료홀 개수가 동일하고 연료 홀 직경이 감소하는 경우와 연료 홀면적이 동일하고 연료 홀 수가 감소되는 경우 연료의 연소용 공기층 침투가 커지기 때문에 NOx의 배출은 감소하지만 화염 안정성은 감소하게 된다. 그리고 동일 연료 홀 면적을 이용하는 분사방식에 있어서 연료 홀을 교차 변경하는 경우 연료의 평균 침투거리 증가로 NOx의 배출이 감소되며 연료 침투거리가 적은 연료가 화염을 안정화시키는 역할을 한다.