• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.848-853
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• 2004

Regarding to the project SUAV (Smart Unmanned Aerial Vehicle) in KARI (Korea Aerospace Research Institute), several engine configurations has been evaluated. However it's not an easy task to collect all the necessary data of each engine for the analysis. Usually, some kind of modeling technique is required in order to determine the unknown data. In the present paper a qualitative method for reverse engineering is proposed, in order to identify some design patterns and relationships between parameters. The method can be used to estimate several parameters that usually are not provided by the manufacturer. The method consists of modeling an existing engine and through a simulation, compare its transient behavior with its operating envelope. In the simulation several parameters such as thermodynamics, performance, safety and mechanics concerning to the definition of operation-envelope, have been discussed qualitatively. With the model, all engine parameters can be estimated with acceptable accuracy, making possible the study of dependencies among different parameters such as power-turbine total inertia, TIT, take-off time and part load, in order to check if the engine transient performance is within the design criteria. For more realistic approach and more detailed design requirements, it will be necessary to enhance the compressor map first, and more realistic estimated values must be taken into account for intake-loss, bleed-air and auxiliary power extraction. The relative importance of these “unknown” parameters must be evaluated using sensitivity analysis in the future evaluation. Moreover, fluid dynamics, thermal analysis and stress analysis necessary for the resulting life assessment of en engine, will not be addressed here but in a future paper. With the methodology presented in the paper was possible to infer the relationships between operation-envelope and engine parameters.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.571-575
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• 2006

To improve economic of solar power generation, stirling engine is required continuous operation and the receiver has to be provided with an additional combustion system. The hybrid receiver with a specially adapted combustion system is possible to 24 hr/day operation by solar and gas-fired. The inner cavity and external wall serve as absorber surfaces using collected irradiation and heat transfer surfaces for the gas heat flow, respectively. The hybrid receiver was designed and fabricated for the dish/stirling system. The analytical method for pridicting natural convective heat loss from receiver is used. The Koenig and Marvin model is used to estimate convection heat loss and heat transfer coefficiency.

• 한국산업융합학회 논문집
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• 제26권2_2호
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• pp.327-332
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• 2023

As interest in eco-friendly and fuel-efficient electric vehicles has increased globally, there has also been a growing interest in the efficiency, vibration, and noise of motors for electric vehicles Electric vehicles generally have significantly lower driving ranges per charge compared to the maximum driving range per fueling of internal combustion engine vehicles. Additionally, there are issues with various vibrations and noise generated by the motor that can cause discomfort for passengers. Therefore, research is necessary to reduce losses, vibration, and noise of the motor to improve the driving range of electric vehicles. IPMSM with a purchased design can obtain additional reluctance torque by utilizing the difference in inductance between the d and q axes. However, due to this reluctance torque, torque ripple occurs larger than other motors. The increase in torque ripple also increases noise and vibration. Since the reluctance torque, which is the main cause of torque ripple, is determined by the shape of the motor components, torque ripple can be reduced through shape optimization. In this paper, a rotor shape for reducing torque ripple and core loss that causes vibration, noise, and efficiency to decrease of IPMSM for electric vehicles was proposed. Optimization design was carried out by changing the shape of the q-axis path of the rotor to reduce the difference in inductance of the d and q-axis of the rotor. Finally, in order to verify the validity of the design variables derived through the optimal design, the original model and the improved model were compared through the FEM. Compared to the original model, the improved model's torque verifying ripple was reduced by about 62% and core loss was reduced by about 29%, the superiority of the improved model.

• Composites Research
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• 제13권3호
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• pp.30-37
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• 2000

계면상 조건과 단섬유 함유량 증가에 따른 강화고무의 동적 특성에 대해 실험적 고찰을 하였다. 손실계수는 대체적으로 섬유 함유량 증가에 따라 감소하였고 계면상 조건에 따라 다른 경향을 보였다. 계면 조건이 우수할수록 손실탄성율, $E_2$ 는 낮게 나타났다. 또한 동배율은 섬유 함유량 증가에 따라 감소하였고, 계면상 조건이 우수할수록 크게 감소하였다. 따라서 단섬유 강화고무는 진동수비가 $\sqrt{2}$이상에서 더 큰 진동절연 효과가 있다고 할 수 있다. 손실계수와 동배률의 관계로부터, 자동차의 엔진과 차체의 진동을 절연하는 부품인 Engine Mount Rubber의 적용가능성을 검토하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.676-681
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• 2001

We usually divide the noise of exhaust system into pulsation noise and flow noise. Pulsation noise is the shock wave to occur when the burning gas of low pressure emits and include harmonic having basic frequency as the exhaust cycle of engine. Flow noise is the noise that is produced when gas flow emits into the atmosphere through the pipe and has the character of frequency like pink noise which has the high level of high frequency component. A muffler is divided into reflective type and absorptive type. We usually use the muffler compounding the property of them. In this study, it is the case of transfer matrix method that a muffler is compounded to analyze the elements of each section according to sound wave's proceed direction. But we use simple model. So, we use finite element method that takes short time to analyze. Acoustic analysis gives us transfer matrix to use FEA of SYSNOISE and we use STAR-CD for fluid analysis. We made database that is based on analytical results about the muffler of expansion type, extended type, offset type, reverse type, and perforated type and developed the muffler design system to perform work efficiently.

• 한국자동차공학회논문집
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• 제4권4호
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• pp.18-26
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• 1996

Based on experimental analysis, the characteristics of pulsating pressure wave propagation is clarified by testing of 4-stroke gasoline engine. The pulsating pressure wave in exhaust system is generated by pulsating gas flow due to working of exhaust valve. The pulsating pressure wave is closely concerned to the loss of engine power according to back pressure and exhaust noise. It is difficult to exactly calculate pulsating pressure wave propagation in exhaust system because of nonlinear effect. Therefore, in the first step for solving these problems, this paper contains experimental model and analysis method which are applied two-port network analysis. Also, it shows coherence function, frequency response function, back pressure, and gradient of temperature in exhaust system.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.546-551
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• 2001

In this paper, an algorithm to improve the optimal engine operation is suggested by increasing the CVT shift speed. By rearranging the CVT shift dynamic equation, it is found that the CVT shift speed depends on the line pressure as well as the primary pressure. Based on the shift dynamics, an algorithm to accomplish a faster shift speed is presented by increasing the line pressure. In order to apply the algorithm, dynamic models of the line pressure control valve and the ratio control valve are obtained by considering the CVT shift dynamics and model based controllers are designed. It is found from the simulation results that fuel economy can be improved by 2% in spite of the increased hydraulic loss due to the increased line pressure.

• 한국소음진동공학회논문집
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• 제15권6호
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• pp.674-679
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• 2005

Statistical Energy Analysis(SEA) has been considered as a Possible method for predicting responses of complex structures, especially at higher frequencies. In this paper, an SEA model of a vehicle was built using 138 energy storing subsystems connected together using 1019 Junctions. SEAM software program was used to build and calculate the model. To demonstrate the accuracy of the SEA model, predicted response levels were compared with measured levels. The source Input levels were measured at the engine mounting parts. There is good agreement between the estimated and the experimental results. This paper also identifies some dominant energy flow paths from sources. It is finally presented that the SEA model can optimize the design parameters of vehicles using model parameters and energy flow paths.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.107-110
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• 2009

터보펌프방식 액체로켓엔진 개발의 일환으로 터보펌프 출구로부터 연소기와 가스발생기의 산화제 밸브에 이르는 액체산소 고압 배관부 기술개발모델(TDM)에 대한 기본설계를 수행하였다. 액체산소 고압 배관부는 직관, 곡관, 벨로우즈, 분기구, 오리피스, 플랜지 및 단열재로 구성되어 있다. 작동 환경, 무게, 제작성을 고려하여 소재를 선정하였다. 요구 유량과 차압 조건을 고려하여 유동해석을 통해 각 구성품의 크기와 위치를 선정하였다. 작동 온도와 최대 예상 작동 압력을 고려하여 각 구성품에 대한 기본 설계를 수행하였으며 구조해석을 통해 안전율을 평가하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제34권2호
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• pp.275-281
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• 2010

선박용 엔진 또는 플랜트 시스템에 사용되는 대형 소음기의 개발단계에서 비용절감 및 개발기간의 단축을 위하여 축소모형으로 대체 실험이 가능하도록 기하상사법을 제안하고자 한다. 대형 소음기를 구성하고 있는 공명형과 단순 확장관형 소음기의 원형과 축소 모형에 대한 이론식으로부터 기하상사 변수를 규명하였다. 그리고 음향해석을 통하여 조합형과 배플형의 축소 모형에 기하상사법을 적용하여 원형모형의 성능을 예측하고, 이를 원형모형의 실제 성능과 비교하는 방법으로 기하상사 변수를 검증하였다.