• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.5
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• pp.60-71
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• 2007

The startup characteristic of liquid propellant rocket engine should be focused on the stable ignition of combustion chamber and gas generator. Also, to lessen the propellants consumption during this period which doesn't contribute to the flight thrust, the engine has to be transferred to the nominal mode quickly. Because of the risk of test, it is impossible to develop all the startup cyclogram or the specifications of engine by test, so the precedent numerical approach is quite necessary. In this study we developed a mathematical model for the startup phenomena in a liquid rocket engine driven by gas generator-turbopump system based on the commercial 1-D flow system analysis program, Flowmaster. Using this program we proposed a methodology to obtain the specifications of turbine starter and the opening time of shutoff valves for the stable startup of the engine. To verify this methodology we qualitatively compared the analysis results to the typical startup curve of the published engine, then found it is quite well matched.

• Proceedings of the Korean Society for Quality Management Conference
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• 1998.11a
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• pp.295-300
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• 1998

Recently graphical modelling is being studied as a useful process analysis tool for exploratory causal analysis. Graphical modelling is a presentation method that uses graphs to describe statistical models of the structures of multivariate data. This paper describes an application of this graphical modeling with two cases from the automotive parts industry. One case is the unbalance problem of the pulley, an automotive generator part. There is multivariate data of the product from each of the processes which are connected in the series. By means of exploratory causal analysis between the variables using graphical modeling, the key processes which causes the variation of the final characteristics and their mechanism of the causal relationship have become clear. Another case is, also, the unbalanced problem of automotive starter parts which consists of many parts and is manufactured by complex machinery and assembling process. By means of the similar technique, the key processes are obtained easily and the results are reasonable from technical knowledge.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.23-24
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• 2013

In recent years, ISG (Integrated Starter and Generator) system receives a great attention for electric electrification of normal gasoline vehicle. As a cost-effect machine design, an ISG without a permanent magnet is considered. A 12slot-10pole field-excitation flux-switching synchronous machine (FEFSSM) is designed and analyzed via JMAG. The active parts such as the field excitation coil and armature coil are located on the stator. The rotor part consisting of single piece iron makes it more robust and suitable to apply for high speed motor drive system application coupled with reduction belt. The design target is the motor with a maximum torque of 40Nm, a maximum power of 10kW and a maximum speed of 14000 rpm. In this paper, design optimization method is proposed for high torque capability.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.796-797
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• 2011

하이브리드 자동차의 Integrated Starter & Generator (ISG)는 기동 시 높은 토크를 발생시키면서 진동과 소음을 동반한다. 이러한 진동 및 소음은 차량의 품질 확보를 위하여 최소화 시켜야 할 필요가 있다. 본 논문에서는 매입형 영구자석 동기 전동기로 설계된 ISG의 진동 및 소음 저감에 관한 연구에 대하여 다룬다. ISG의 진동 및 소음 저감을 위하여 회전자 코어의 형상 최적설계, 슬롯 수 변경설계 그리고 회전자의 step skew를 적용시켜 각각의 설계방법이 ISG의 진동 및 소음에 미치는 영향을 해석과 실험을 통해 검증하였다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.676-677
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• 2015

본 논문에서는 매입형 영구자석 동기전동기로 Belt-Type ISG(Integrated Starter Generator)를 설계하였다. 전동기는 저속영역에서 동손이 크고, 고속 영역에서는 철손의 비중이 크게 나타난다. ISG의 경우 전동기로 동작하는 저속영역은 동작시간이 짧기에 효율이 크게 중요하지 않지만 발전기동작은 고속영역에서 장기간 이루어지기에 이 구간에서 효율을 높이는 것이 중요하다. 특히 분포권에서는 전체 손실성분 중에서 회전자의 영구자석 기본파와 고조파 기자력에 의해 발생하는 치에서의 철손이 가장 큰 비중을 차지한다. 본 논문에서는 분포권에서의 철손에 대해서 분석하고 주된 손실의 원인인 치에서의 철손을 저감하는 설계를 수행하여 효율을 향상시켰다.

• Journal of Aerospace System Engineering
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• v.3 no.2
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• pp.20-23
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• 2009

The structural analysis of liquid rocket engine was performed in the case of sinusoidal vibration load to verify structural safety. The finite element model is composed with main liquid rocket engine components, combustion chamber, turbopump, gas-generator, pyro-starter, main pipes, main valve, heat-exchanger, gimbal-mount and brackets. Natural vibration mode analysis and structural analysis for sinusoidal vibration load were performed. The natural mode frequency of liquid rocket engine is twice than that of launch vehicle. In the case of stress result of sinusoidal vibration load, the part of maximum stress has 1.4 margin, so the engine structure is safe for sinusoidal vibration load.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.1
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• pp.37-42
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• 2013

This paper deals with Wound Rotor Synchronous Motor (WRSM) purposely designed for Integrated Starter and Generator (ISG) installed in 42V automotive electrical system. Not only design objective and specifications of WRSM, but its adaptive design to minimize torque ripple and back-EMF Total Harmonics Distortion (THD) are considered. Furthermore, design characteristics of designed prototype have been investigated numerically in terms of torque, back EMF, loss, and efficiency, which are verified by performance comparison with Interior Permanent Magnet Synchronous Machine based on Finite Element Analysis (FEA).

• Journal of Electrical Engineering and Technology
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• v.11 no.3
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• pp.609-617
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• 2016

Belt-driven Starter Generator (BSG) differs from other mild hybrid systems as the crankshaft of vehicle are not run off. Motor permits a low-cost method of adding mild hybrid capabilities such as start-stop, power assist, and mild levels of regenerative braking. Wound rotor synchronous motor (WRSM) could be adopted in BSG system for HEV e-Assisted application instead of the interior permanent magnet synchronous motor (IPMSM). In practice, adequate torque is indispensable for starter assist system, and energy conversion should be taken into account for the HEV or EV as well. Particularly, flux weakening control is possible to realize by adjusting both direct axis components of current and field current in WRSM. Accordingly, this paper present an off-line current acquisition algorithm that can reasonably combine the stator and field current to acquire the maximum torque, meanwhile the energy conversion is taken into consideration by losses. Besides, on account of inductance influence by non-uniform air gap around rotor, nonlinear inductances and armature flux linkage against current variation are proposed to guarantee the results closer to reality. A computer-aided method for proposed algorithm are present and results are given in form of the Look-up table (LUT). The experiment shows the validity of algorithm.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.9
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• pp.1228-1233
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• 2013

In this paper, design of Wound Rotor Synchronous Motor(WRSM) for Integrated Starter and Generator(ISG) is performed based on Finite Element Analysis(FEA). WRSM can control not only magnitude and phase of armature current, but also field current. Thus, various control methods can be considered. Since driving characteristic of WRSM depends greatly on the control method, characteristic analysis accoding to possible driving current combination is reguired. Especially in high speed region, the control method that reduces unnecessary d-axis current by reducing field current is possible, which is similar to field weakening control. By the current combination reducing field and d-axis current, the design minimizing copper loss to increase efficiency on identical driving point is possible. In this paper, high efficient WRSM is designed applying the current combination which can minimize copper loss on each driving point.

• International Journal of Automotive Technology
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• v.8 no.6
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• pp.781-790
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• 2007

Hybrid electric vehicles(HEV) combined with more than one power sources have great potential to improve fuel economy and reduce pollutant emissions. The Integrated Starter Generator(ISG) HEV researched in this paper is a two energy sources vehicle, with a conventional internal combustion engine(ICE) and an energy storage system(batteries). In order to investigate the potential of diesel engine hybrid electric vehicles in fuel economy improvement and emissions reduction, a Dynamic Programming(DP) based supervisory controller is developed to allocate the power requirement between ICE and batteries with the objective of minimizing a weighted cost function over given drive cycles. A fuel-economy-only case and a fuel & emissions case can be achieved by changing specific weighting factors. The simulation results of the fuel-economy-only case show that there is a 45.1% fuel saving potential for this ISG HEV compared to a conventional transit bus. The test results present a 39.6% improvement in fuel economy which validates the simulation results. Compared to the fuel-economy-only case, the fuel & emissions case further reduces the pollutant emissions at a cost of 3.2% and 4.5% of fuel consumption with respect to the simulation and test result respectively.