• 수산해양교육연구
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• 제28권2호
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• pp.465-472
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• 2016

본 연구에서는 2010년부터 2014년까지 최근 5년간 우리 나라 주변해역에서 발생하여 중앙해양안전심판원의 재결을 마친 1417건의 해양사고에 대해 이를 25개 요인별로 분류하고, SPSS 통계 프로그램에 의한 주성분분석(Principal Component Analysis; PCA)을 행하여 이들 각 요인들의 상관성 및 주요 해양원인을 분석 고찰하였다. 얻어진 주요한 결과들을 요약하면 다음과 같다. 1. 해양사고의 주된 원인은 기관설비취급불량, 화기취급불량, 항행법규소홀, 침로선정유지불량, 경계소홀 등 기관실 및 조타실 관련 인적요인에 의해 발생한다. 2. 조타실 관련 인적요인에 의해 발생하는 사고는 충돌과 좌초 등이 큰 비중을 차지하며, 기관실 관련 인적요인에 의해 발생하는 사고유형은 주로 기관손상이나 화재폭발 등이다. 3. 주성분분석의 결과 제1주성분은 해양사고의 출현율을, 제2주성분은 해양사고의 원인을, 제3주 성분은 해양사고의 유형을 나타낸다.

• 한국유체기계학회 논문집
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• 제20권1호
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• pp.65-73
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• 2017

Intercoolers for multi-stage turbocharger of the hydrogen reciprocating engine for HALE UAV are installed for reducing the charged air inlet temperature of the engine. The intercooler is air to air, cross flow, plate-fin type and the fin configuration is offset-strip fin which is referenced from the heat exchanger of the ERAST. Most of HALE UAV's cruising altitude is 60,000 ft and the density of air for this altitude is very low compared to sea level. Therefore the required heat transfer area for the HALE UAV is about three-times bigger than the sea level. Consequently, it is essential to design to meet the required efficiency of intercooler in the range of not excessively growing the weight of the heat exchanger. The quasi-one dimensional heat transfer design/analysis for satisfying the requirement of the engine are written in this paper. The numerical analyses for estimating the coolant flow rate of the engine bay and pressure loss in the header and core are also summarized.

• 한국자동차공학회논문집
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• 제11권4호
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• pp.58-67
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• 2003

An automotive engine cooling system is closely related with overall engine performances, such as reduction of fuel consumption, decrease of air pollution, and increase of engine life. Because of complex reaction between each component, the direct experiment, using a vehicle, takes high cost, long time, and slow response to the system change. Therefore, a computer simulation would provide the designer with an inexpensive and effective tool for design, development, and optimization of the engine cooling system over a wide range of operating conditions. In this work, it has been predicted the thermal performance of the engine cooling system in cases of stationary mode, constant speed mode, and city-drive mode by mathematical modelling of each component and numerical analysis. The components are engine, radiator, heater, thermostat, water pump, and cooling fans. Since the engine model is the most important, that is divided into eight sub-sections. The volume mean temperature of eight sub-sections are simultaneously calculated at a time. For detail calculation, the radiator and heater are also divided into many sub-sections like control volumes in finite difference method. Each sub-section is assumed to consist of three parts, coolant, tube with fin, and air. Hence it has been developed the simulation program that can be used in case of design and system configuration changes. The overall performance results obtained by the program were desirable and the time-traced tendencies of the results agreed fairly well with those of actual situations.

• 동력기계공학회지
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• 제9권3호
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• pp.15-20
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• 2005

In this paper, the effect of oxygen component in fuel on the exhaust emissions has been investigated for an indirect injection diesel engine. It was tested to estimate change of engine performance and exhaust emission characteristics for the commercial diesel fuel and oxygenated blended fuel which has four kinds of mixed ratio. And, the effects of exhaust gas recirculation(EGR) on the characteristics of NOx emission have been investigated. Ethylene glycol mono-n-butyl ether(EGBE) contains oxygen component 27% in itself, and it is a kind of effective oxygenated fuel of mono-ether group that the smoke emission of EGBE is reduced remarkably compared with commercial diesel fuel, that is, it can supply oxygen component sufficiently at higher loads and speeds in diesel engine. It was found that simultaneous reduction of smoke and NOx was achieved with oxygenated fuel(10vol-%) and cooled EGR method(10%).

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.948-954
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• 2002

The structural vibration of a diesel generator set was investigated through analyses and tests. FE modeling and normal mode analysis were performed and compared with measured results for both structure components and generator set assembly. The results of component analyses were fairly well coincident with measured results but those of assembled generator set showed more or less discrepancies. Discussions were given about the uncertainties for vibration characteristics of component structures and assembled running structures especially concerning their nonlinearities and damping effects. Detailed excitation analysis fellowed by forced response analysis was done from the engine and pressure data to compare with the actual measured vibration. As results the vibration prediction for frame structures of reciprocating internal combustion engine was confirmed reliable to some extent.

• 항공우주시스템공학회지
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• 제7권4호
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• pp.49-54
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• 2013

A turbopump for a 75 ton class liquid rocket engine was tested at full speed for 20 seconds using model fluid. Liquid nitrogen is used for the oxidizer pump, water for the fuel pump, and hot gas for the turbine. The non-cavitating head of pump from the turbopump assembly test showed a good agreement with that from the pump component test. The relative difference of turbine efficiency between the turbopump assembly test and the turbine component test was 0.3% only. Suction performance from the turbopump assembly test was higher than that of pump component test, which resulted from the thermodynamic effect of cavitation.

• Journal of Biosystems Engineering
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• 제26권1호
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• pp.11-20
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• 2001

Experiments under the stationary and harvesting condition, were performed in order to investigate the vibration characteristics of a head-feeding combine. 6 degrees of freedom components of acceleration at the location of the center of the gravity, and 3 degrees of freedom components of acceleration at the location of the operator seat were measured independently. The vibration characteristics of the combine were estimated with the power spectral density of the time series data of accelerations. From this research, the following results were obtained. 1. Vibration of a head-feeding combine under the stationary condition(engine, thresher and cutter are driven without harvesting) is mainly influenced by the engine. Further, 1/3, 1/2 (sub-harmonic) frequency components of the engine are observed besides engine driving frequency component(45Hz). 2. Vibration of a head-feeding combine under the harvesting condition is influenced by the engine, threshing unit and driving unit. Namely, some kinds of vibration frequency components in harvesting are observed compared with stationary condition. Further, sub-harmonic frequency components of the engine are observed besides engine driving frequency component as same as stationary condition. From these results, it may be concluded that vibration of a head-feeding combine is characteristics of semi-periodic and nonlinear vibration.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.572-582
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• 2017

공기 흡입 엔진을 개발하기 위해서는 지상 시험을 통한 추력 측정이 반드시 필요한데, 공기 흡입 엔진은 추력 측정 장치에서 측정된 값 이외에도 엔진 흡입구로 들어오는 공기 유동에 의한 힘을 고려하여 총추력을 계산해야 한다. 또한 다분력 추력 측정 장치를 활용하여 요와 피치 방향의 측추력도 정확하게 측정하고 분석할 수 있어야 한다. 래버린스 씰 격리, 1축 총추력 계산, 다분력 추력 측정 장치 개발, 측추력 분석 등의 일련 과정을 통해 공기 흡입 엔진의 총추력을 정밀하게 추정하여 엔진 성능을 보다 정확하게 평가할 수 있게 하였다.

• 한국추진공학회지
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• 제17권1호
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• pp.70-79
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• 2013

본 연구에서는 중형 항공기의 추진 기관인 2 스풀 분리-배기 형식 터보팬 엔진 (BR715-56)의 성능 해석을 수행하기 위하여 상용코드인 MATLAB/SIMULINK를 이용하여 성능모델을 구성하였으며 유량 및 일 조합에 새로운 조합 서브시스템 블록을 새로이 개발하였다. 성능 모사는 먼저 팬, 고압압축기, 고압터빈, 저압터빈 구성품 성능 맵들을 축척방법을 이용하여 유사성능 맵들로 부터 생성하였고, 다음은 탈설계점 성능 해석을 할 수 있도록 구성품들 간 유량과 일 조합이 이루어 질수 있도록 하였다. 제안된 SIMULINK 성능모델은 정상 및 동적 모사와 사용자 편의의 장점을 가지고 있으며, 다양한 작동 조건들에서 개발된 프로그램을 이용한 탈설계점 해석 결과들이 GASTURB에 의한 해석 결과들과 잘 일치함이 확인 되었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1697-1702
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• 2003

In this paper, the effect of oxygen component in fuel on the exhaust emissions has been investigated for a direct injection diesel engine. It was tested to estimate change of engine performance and exhaust emission characteristics for the commercial diesel fuel and oxygenated blended fuel which has seven kinds of mixed ratio. And, the effects of exhaust gas recirculation(EGR) on the characteristics of NOx emission have been investigated. Ethylene glycol mono-n-butyl ether(EGBE) contains oxygen component 27% in itself, and it is a kind of effective oxygenated fuel of mono-ether group that the smoke emission of EGBE blended fuel is reduced remarkably compared with commercial diesel fuel, that is, it can supply oxygen component sufficiently at higher loads and speeds in a diesel engine. It was found that simultaneous reduction of smoke and NOx was achieved with oxygenated fuel and cooled EGR method.