• Aerospace Engineering and Technology
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• v.12 no.1
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• pp.105-110
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• 2013

The gimbal expansion joint for the pipe line of a liquid rocket engine undergoes high pressure and cyclic rotational displacement loadings. In present study, the moment analyses and tests of the internal-type gimbal expansion joint for the engine were performed. The moment components due to spring stiffness, friction and lateral force were obtained using a analytic method and their sums at low and high pressures were compared with the test results. Also, applying a $MoS_2$ dry film lubricant to the pin of a external hinge expansion joint, it is tested that the galling of the pin was removed and the friction coefficient was decreased for low pressures.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.08a
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• pp.67-72
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• 2008

본 논문에서는 하이브리드 차량 내부 전기모터의 등판 마력값과 회전 RPM, 흡기온도 센서의 온도 변화와 공기 및 연료의 혼합비율인 공연비에 대해 퍼지 제어 기법을 적용하여 차량의 연료 소비를 제어하는 방법을 제안한다. 제안된 기법에서는 초기 가속부분에서 등판 마력간과 회전 RPM을 퍼지제어 규칙에 의해 전기모터와 엔진의 사용비율을 제어하고, 엔진이 가동될 때 각각의 공기유입량과 연료 분사량을 이용하여 공연비 수치를 구한 후, 공연비, 흡기온도, 최종 연료 보정량에 대해 설정된 피지 소속 함수와 퍼지 추론 규칙에 따라 차량 연료를 제어한다. 시뮬레이션을 통하여 실험한 결과, 제안된 퍼지 제어 기법을 이용한 엔진 및 연료 제어 방법이 퍼지기법을 적용하지 않은 제어방법보다 평균연비가 개선되어 제안된 연료 제어 방법이 효율적임을 확인하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.752-755
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• 2004

선박용 엔진의 제작에 있어 크랭크 샤프트 조립 시 1 회전의 상태에서 크랭크 스루 간의 디플렉션의 상대값이 정상오차 범위를 넘어서는지 확인한 후 조립상태를 보정하게 된다. 기존의 방법은 다이얼 게이지를 사용하여 측정 담당자가 베드 플레이트 내에 들어가 크랭크 샤프트 회전 시 따라 돌면서 직접 육안 확인을 통해 측정이 이루어졌다. 이 때, 측정의 불편함과 열악한 작업환경 하의 안전 문제가 야기된다. 이러한 문제점을 해결하기 위해 본 연구에서는 블루투스 통신을 이용하여 디지털 게이지를 사용한 측정장치 기구부의 신호를 무선으로 받아서 작업자는 베드 플레이트 외부에서 측정이 가능하도록 하는 시스템의 개발하였다. 이를 통해 작업의 편리성 및 안정성을 확보했으며, 디지털 측정을 통한 측정의 정확도를 향상시켰다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.167-170
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• 2006

For a short time a pyre-starter should turn the blades of a turbine to the adequate rotational speed by a single operation. Through this process the pressures of the components of a propellant rise rapidly up to the operating point, and the components enter into a gas-generator. Combustion in the gas-generator occurs to keep the turbopumps working. In this research characteristic parameters of a pyre-starter which correspond to the required performance of the turbopump before the gas-generator starts to work were selected

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.3
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• pp.112-118
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• 2006

In this paper, we presented experimental data of the strength of the electro-magnetic waves in the engine room of automobiles. Measured frequency ranges are $145{\sim}380MHz$ and $844{\sim}1044MHz$. Experimental studies are conducted by measuring the radiated power of the frequency spectrum for above frequency bands. The $\lambda/2$ dipoles used for measurement are fabricated to comply with the COMMISSION DIRECTIVE 95/54EC. Experimental results confirm that the level of radiated power in the engine room at idling rpm is about 3dB higher than that of 1500rpm.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.1
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• pp.46-52
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• 2005

A propeller as a propulsion system has been redesigned to improve performance of a target drone. The vortex theory has been applied for the propeller design method. Design variables have been the chord length along the direction of blade radius, the change of blade radius, and the geometric angle of the blade. The existing propeller has been redesigned and modified considering engine RPM change to get the improved thrust at both low and high speeds.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.143-144
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• 2015

전기추진선박은 디젤엔진과 프로펠러의 회전축이 기계적으로 연결된 기존의 선박과 달리 엔진의 기계적 에너지를 전기 에너지로 변환하여 전동기 회전을 통해 추진력을 얻는 선박으로서 시추선, 군함, OSV(Offshore Support Vessel)등 높은 조종성능이 요구되는 선종에 주로 적용되고 있다. 이러한 선종은 추진력을 얻는데 가장 큰 전력을 사용하므로 날씨에 따른 전력부하량의 변동이 크다. 본 논문에서는 슈퍼커패시터로 구성된 전력버퍼모듈을 이용하여 전기추진선박의 효율적인 전력 운용 전략을 제안한다. 추진전동기의 VFD(Variable Frequency Drive)의 직류단을 전력버퍼모듈로 통합하여 각 전동기의 보조전력으로 활용함으로써 부하변동에 빠르게 대응할 수 있으며, 주 전원의 느린 응답성을 보상하여 조종성능을 향상시킬 수 있다. 제안된 전력버퍼모듈은 시뮬레이션을 통해 그 유용성을 검증하였다.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.5
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• pp.62-70
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• 2015

A liquid rocket engine system can cause rapid pressure and temperature variations during the startup period. Thus the startup analysis is required to reduce time and expense for successful development of liquid rocket engine through the startup prediction. In this study, a startup analysis simulator is developed for a staged combustion cycle engine powerpack. This simulator calculates propellant flow rates using pressure and flow rate balances. In addition, a rotational speed of turbopump is obtained as a function of time by mathematical modeling. A startup analysis result shows that the time to reach a steady-state and a rotational speed at the steady-state are 1.3 sec and 27,500 rpm, respectively. Moreover it can indicate proper startup sequences for stable operation.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.2
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• pp.42-53
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• 2009

Gas turbine engine simulation program has been developed. In compressor and turbine, 2-D NS implicit code is used with k-$\omega$ SST turbulent model. In combustor, 0-D lumped method chemical equilibrium code is adopted under the limitations, the products are only 10 species of molecular and air-fuel is perfectly mixed state with 100% combustion efficiency at constant pressure. Fluid properties are shared on interfaces between engine components. The outlet conditions of compressor have been used as the inlet condition of combustor. The inlet condition of turbine comes from the compressor The back pressure in compressor outlet is transferred by the inlet pressure of turbine. Unsteady phenomena at rotor-stator in compressor and turbine is covered by mixing-plane method. The state of engine can be determined only by given inlet condition of compressor, outlet condition of turbine, equivalence ratio and rotating speed.

• Journal of the Korea Convergence Society
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• v.6 no.6
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• pp.279-284
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• 2015

The vibration happened at the revolution movement of driving shaft driven with the thrust of airplane affects the great influence on the life of the shaft. And a great loss of life is caused when the fatigue damage is occurred at the driving shaft during revolution. The chattering is occurred at the driving shaft placed at the various revolution due to the aviation environment. Therefore, the part of the driving shaft concerned about the fatigue damage is grasped through the analysis study in this paper. So, the durability to prevent damage can be improved and it is possible to be grafted onto the convergence technique on the basis of a recent safe design and show the esthetic sense.