• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3317-3322
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• 2007

THC(Total Hydrocarbon) emissions during cold start and warm-up phase constitute the majority of THC emissions during the FTP-75 mode. As the basic approach to improve the emission performance of Gasoline engine during transient phase, the effect of spark timing retard from MBT on THC emission characteristics is studied by engine test using a Fast response Flame Ionization Detector(FFID). A cyclic analysis of the combustion process shows that high THC emissions are produced first few cycles during the transient phase. This paper presents the results of engine performance and emission of Gasoline engine with various spark timing. consequently, This paper was focused on the combustion phenomena with various spark timing during transient phase which was analyzed by Fast response Flame Ionization Detector (FFID) equipment to measure the cyclic THC emission characteristics.

• Journal of Magnetics
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• v.21 no.3
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• pp.413-420
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• 2016

The permanent magnet synchronous motor has high efficiency driving performance and high power density output characteristics compared with other motors. In addition, it has good regenerative operation characteristics during braking and deceleration driving condition. For this reason, permanent magnet synchronous motor is generally applied as a power train motor for electrical vehicle. In permanent magnet synchronous motor, the most probable causes of fault are demagnetization of rotor's permanent magnet and short of stator winding turn. Therefore, the demagnetization fault of permanent magnet and turn fault of stator winding should be detected quickly to reduce the risk of accident and to prevent the progress of breakdown of power train system. In this paper, the fault diagnosis method using high frequency low voltage injection was suggested to diagnose the demagnetization fault of rotor permanent magnet and the turn fault of stator winding. The proposed fault diagnosis method can be used to check the faults of permanent magnet synchronous motor during system check-up process at vehicle starting and idling stop mode. The feasibility and usefulness of the proposed method were verified by the finite element analysis.

• Proceedings of the KIEE Conference
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• 2008.04c
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• pp.110-112
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• 2008

A linear generator driven by a hydrogen combustion engine has been developed. Unlike rotary engine-generator systems, the linear counterpart is inherently unable to start by itself unless external force is provided for initial compression/ignition cycle. When the generator is connected to utility power lines through a bidirectional power conversion system, however, the self start-up can be done by driving the generator as a motor. This paper introduces a prototype 1kW linear hydrogen engine-generator system being developed and shows the self start-up is possible with proper motoring mode.

• Proceedings of the KIPE Conference
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• 2001.12a
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• pp.37-40
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• 2001

This paper is suggested an optimal switching angle of a switched reluctance motor drive system for maximum energy ratio. A new magnetizing method with a low-frequency increasing the energy conversion ratio that is related to the efficiency of motor is proposed As results, it improves the efficiency about 2[$\%$]. And a torque ripple is also reduced compared with that of the conventional switching angle magnetizing approach. In order to start softly regardless of a large ripple torque, the profile of phase current is predicted and current control mode was adapted when it is operated under the starting speed.

• Proceedings of the KIEE Conference
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• 2007.04c
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• pp.124-125
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• 2007

본 연구에서는 Free-piston 엔진용 원통형 선형 발전기의 전동기 운전을 이용한 기동에 관한 연구를 수행하였다. Free-piston 엔진의 피스톤이 흡기, 압축, 폭발, 배기 과정에 따라 정상 상태로 왕복운동을 하기 위해서는 기동 시 정지상태인 피스톤을 외부의 힘으로 움직여 연소실에 있던 공기를 밀어내고, 연료를 연소실안에 흡입한 뒤 다시 압축시켜 플러그를 통해 폭발시켜 주어야 한다. 이 과정에서 별도의 전동기를 사용하는 대신 Free-piston 엔진에서 사용하는 원통형 선형 발전기를 전동기로 사용하여 엔진의 기동을 위해 요구되는 속도와 토크를 만족시키는지 동특성 해석을 하였고, free-piston 엔진을 기동시키기에 충분한 속도와 토크를 낼 수 있다는 결론을 얻었다.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.224-227
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• 2004

The goal of this paper is optimal switching angle of switched reluctance motor drive system for maximum energy ratio. A new magnetizing method with a low-frequency increasing the energy conversion ratio that is related to the efficiency of motor is proposed. As results, it improved the efficiency about $2[\%]$. And a torque ripple is also sufficiently reduced compared with that of the conventional switching angle magnetizing approach. In order to start softly regardless of a large ripple torque, the profile of phase current is predicted by the ANFIS, and current control mode was adapted when it is operated under the starting speed. Variable implementations on the fields will guarantee the more practical drive system.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.460-461
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• 2006

Computer Loads can be found in all of modern society. The switching mode power supplies used in personal computers are major sources of harmonic currents. Harmonic currents can cause lots of harmonic problems such as disruption in computer performance. A series resonant filter is very effective in harmonic reduction for personal computer loads. Voltage sags are short duration reductions in rms voltage. The main causes of voltage sags are faults, motor starting, and transformer energizing. Personal computers are another example of devices sensitive to voltage sags. A serious voltage sag at the terminals way lead mis-operation of the equipment. This paper presents an in depth analysis to evaluate the effect of harmonics reduction based on the IEC 61000-3-2 and the effect of voltage sag using ITI curve by applying a series resonant filter for personal computer loads.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.4
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• pp.165-173
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• 2002

The goal of this paper is optimal switching angle of switched reluctance motor drive system fur maximum energy ratio. A new magnetizing method with a low-frequency increasing the energy conversion ratio that is related to the efficiency of motor is proposed. As the results, it improved the efficiency about 2[%]. And a torque ripple is also sufficiently reduced compared with that of the conventional approach. In order tn start softly regardless of large ripple torque, the profile of phase current is predicted by the ANFIS, and current control mode was adapted when it is operated under the starting speed. Variable implementations en the fields will guarantee the more practical drive system.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.390-395
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• 2003

Moving flexible structures such as transfer systems in press machine, crane, working table of machine tools have vibration problems because of starting, feeding and stopping. An analysis method is suggested and experimentally studied in order to solve a vibration problem of a moving flexible structure. In this method, the concepts of substructure synthesis method and semi-static displacement including rigid body mode were used. Total deformation of a structure was assumed to be composed of quasi-static and dynamic components. Experimental results from an elementary model of a transfer feeder showed good agreements with computational results.

• Corrosion Science and Technology
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• v.4 no.5
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• pp.201-206
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• 2005

Starting with the meaning of the word quality, diverse concepts connoted by the term are examined. Instead of a bathtub curve, the desirable shape of a failure rate covering the entire life of a good product, which might be called hockey-stick line, is introduced. From the hockey-stick line and the definition of reliability, two measurements are extracted. The terms r-reliability (failure rate) and durability (product life) are explained. The conceptual analysis of failure mechanics explains that reliability technology pertains to design area. The desirable shape of hazard rate curve of electronic items, hockey-stick line, clarifies that Mean-Time-to-failure (MTTF) as the inverse of failure rate can be regarded a nominal life. And Bx life, different from MTTF, is explained. Reliability relationships between components and set products are explained. Reshaped definitions of r-reliability and durability are recommended. The procedure to improve reliability and the reasons for failing to identify failure mode are clarified in order to search right solutions. And generalized Life-Stress failure model is recommended for the calculation of acceleration factor.