• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.388-390
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• 2003

Recent trend of sensor-less control of induction motor applied for commuter trains in Japan is introduced. Although many inverter-fed Induction motor driven trains have been produced so far, most of them were slip frequency based conventional V/f control system using shaft encoder. There arises a new trend to apply speed sensor-less vector control., for this inverter-fed induction motor drive system. The purpose of sensor-less control is to save, cost and improve system reliability. Several sensor-less systems now under testing on the actual railway company. This paper describes the survey of the fundamental structure and feature of representative sensor-less systems mentioned above.

• Advances in aircraft and spacecraft science
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• v.1 no.1
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• pp.43-67
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• 2014

This paper presents a new conceptual design model ACAD (Adaptable Conceptual Aircraft Design), which differs from the other models due to its considerable adaptability to the different classes of aircraft. Another significant feature is the simplicity of the process which leads to the preliminary design outputs and also allowing a substantial autonomy in design choices. The model performs the aircraft design in terms of total weight, weight of aircraft subsystems, airplane and engine performances, and basic aircraft configuration layout. Optimization processes were implemented to calculate the wing aspect ratio and to perform the design requirements fulfillment. In order to evaluate the model outcomes, different test cases are presented: a STOL ultralight airplane, a new commuter with open-rotor engines and a last generation fighter.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.49-58
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• 2008

The function of river navigation is being reconsidered from the viewpoints of environment-friendly and energy-efficient, easing traffic congestion, emergency transport in disaster, and supporting tourism and recreation activities, etc. The purpose of this study is to identify current trends and problems of river navigation in Japan and indicate the role that river navigation should play in future and the directionality of development. This study focused on disaster prevention function with especially high importance degree in metropolitan area from among various functions of river navigation, and showed potential of river navigation corresponding to stranded commuter who is examined as a serious problem in government.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.836-842
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• 2007

Recently it is a tendency that Diesel rolling stock is committing in the commuter's train route of the suburb for solving commuting traffic congestion. It has advantage which expense of diesel rolling stock is relatively cheaper than electric rail car or high-speed train. In addition, it can be using the exist route without large-scale facility investment. Because of this advantage, the demand of diesel rolling stock occupy regular portion from overseas railway car market. GM/RT 2100 specifies the loads vehicle bodies shall be capable of withstanding, identifies how material data shall be used and presents the principles to be used for design verification by analysis. Therefore, in order to fulfill the structural requirements, Rotem Company has carried out Finite Element Analysis (FEA) to verify whether the carbody structure has enough strength to withstand the loads specified by GM/RT 2100. This research contains the results obtained by the analysis. The analysis was carried out using I-DEAS 12 NX Series

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.998-1001
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• 2003

Recent trend of sensor-less control of induction motor applied for commuter trains in Japan is introduced. Although many inverter-fed induction motor driven trains have been produced so far, most of them were slip frequency based conventional V/f control system using shaft encoder. There arises a new trend to apply speed sensor-less vector control., for this inverter-fed induction motor drive system. The purpose of sensor-less control is to save, cost and improve system reliability. Several sensor-less systems now under testing on the actual railway company. This paper describes the survey of the fundamental structure and feature of representative sensor-less systems mentioned above.

• Proceedings of the KOR-KST Conference
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• 1998.10a
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• pp.83-92
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• 1998

서울과 일산 신도시의 출근통행 교통수단 선택모형을 구축하고, 두 도시간 수단선택행태를 분석.비교하였다. 분석을 위한 자료로는 1996년 서울시에서 수행한 가구통행실태조사자료를 이용하였으며, 수단선택모형으로는 다항로짓모형을 사용하였다. 두 지역 출근통행 수단선택모형의 모형구조상의 차이 및 모형의 지역간 이전가능성을 분석하였고, 출근통행의 시간가치 및 탄력성을 분석하고 비교하였다. 통계적 검증의 결과 출근통행의 수단선택에 있어서, 모형구조적 측면에서나 선택행태적 측면에서 수단 선택모형의 두 도시간 이전은 불가능한 것으로 나타났다. 서울의 출근통행의 시간가치가 일산보다 전반적으로 큰 것으로 분석되었고, 특히 서울의 경우, 택시이용자의 시간가치가 자가용 이용자의 시간가치보다 큰 것으로 나타났다. 두 도시 모두 통행시간에 대한 탄력성 통행비용에 대한 탄력성보다 전반적으로 크며, 버스와 지하철간의 통행시간에 대한 교차탄력성이 매우 높은 것으로 분석되었다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.3
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• pp.313-320
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• 1999

A PFC(Perfluorocarbon) heat pipe has been used recently for cooling of GTO(gate turn off) thyristors or diodes in electric commuter trains. The present study was conducted to determine heat transport limitation of a PFC heat pipe which is one of the important parameters in heat pipes design. The variables such as tube diameter, fill charge ratio, internal surface structure and operating temperature were examined by way of experiment. Experimental data showed that the heat transport limitation of PFC heat pipe was considerably low and mostly dependent on tube diameter, with the value of 440~500W for d$o$/=22.23mm and 150~200W for d$o$=15.88mm. The other parameters had negligible effects, except for the case of small charge ratio less than 30%. Some correlations proposed by previous studies were in agreement with data from this study within 10~30%.

• Proceedings of the KSR Conference
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• 2002.10b
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• pp.801-806
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• 2002

The operation of double deck train have increased in many countries such as Japan france, and the Netherlands as efficient, safe and convenient alternative transportation systems. Because of continuous concentration of population into Seoul metropolitan and serious traffic jam, the number of passengers using the commuter train have been increased rapidly. Considering these situations, we can find one of the solutions for heavy traffic problems through double deck trains. Stainless steel, and aluminum extruded panel are used to reduce the weight of double deck train. In this paper we compare the results of structural analysis of the double deck car body structures with Al extruded panels and stainless steel. We hope the results of this study may be used as basic guidelines in designing double deck trains in the future.

• Journal of Families and Better Life
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• v.21 no.2
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• pp.213-220
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• 2003

In this study, I analyzed dual-career commuting couples time use. Concretely, this study compared the husband with the wife on the becoming a commuter family, the living apart on weekdays. And it examined time use on weekdays and weekends by the time amount of each activities and the ratio of actor on each hour. The survey participants included 131 married people who were dual-career commuting couple and who were maintained separate residence and work place. The major findings are as follows: First, weekday separation of the dual-career commuting couples is largely due to career. This kind separation is mostly due to sociostructural labor market factor and individual factor to increasing working women. Second, 94.6%(53) of male participants were resident living apart from their family on weekdays. Third, the most wives mentioned some kind of emotional liberation such as freedom on weekdays. Finally, there was gender difference in the time spent on each activities when dual-career commuting couples are living together and they are apart. Especially the most gender difference on weekdays is household work time and leisure time.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.412-417
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• 2003

In recent years, efficient commuter transportation has become one of major issues to be taken into account around Seoul metropolitan area. In oder to solve the problems, several countries such as Japan, France and so on gradually operate double deck trains as efficient, reliable and comfortable mass transportation systems. However, the double deck trains have relatively big cross sectional areas and high mass centers that cause unsafe vehicle running performances and interface problems between the vehicles and infrastructures, and do not have enough spaces for electric equipments. Therefore, prior to operate double deck trains on the existing lines in Korea, careful investigations should be performed. For these reasons, we have studied the double deck train system for the existing lines around Seoul metropolitan area as an alternative way to carry heavy transportation efficiently and comfortably.