• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.364.2-364
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• 2002

Thermoacoustic oscillation, which stems from phase correlation between unsteady heat release and acoustic fluctuation, can cause severe vibration and incite the excessive local heat transfer inside the rocket engine. It is very important to understand and prevent this phenomenon in the way of rocket engine development. In this study, the propulsion test facility of KSR-III, which is the first liquid propellant rocket developed by KARI, will be introduced. and the characteristics of thermoacoustic ocillation occurred at the facility will be examined.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.174-181
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• 2002

In this paper, we introduce the software of the measuring system for on-line test and evaluation of high speed rail. This software should set and control the hardware of the measuring system, perform the analysis and calculation of measuring data and interface between users and the measuring system. For this purpose, three programs, such as a measuring program, a monitoring program and post-processing program, have developed.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.557-563
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• 2010

Mode II interlaminar fracture toughness was measured and fractured surfaces were observed of carbon/epoxy and glass/epoxy woven fabric composites for carbody structure. Woven fabric carbon/epoxy and glass/epoxy composites that made with prepreg and epoxy resin(RS1222) are used in carbody structure of Korean tilting train(TTX) and low floor bus. ENF(End Notched Flexure) specimens having $120mm{\times}20m{\times}5mm$ shape and 35mm initial crack were made with each composites and three point bending tests according to ASTM D790 were conducted for these specimens. Crack lengths in tests were recorded using optical microscope and digital camcorder. NL(Non Linear), 5% offset and Max. load points in load -displacement curves were checked and mode II interlaminar fracture toughness of these points were calculated and compared. Fractured surfaces of specimens were observed using optical microscope and mode II delamination behavior of each composites was discussed.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1525-1538
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• 2008

Currently, it has been a fashion to include RAMS of rolling stock in the order for purchasing the rolling stock. However, it's only to suggest a qualitative value or an ideal target without giving or demonstrating actual RAMS target, with only demonstrating passive RAMS by the data provided by the manufacturer. In the case of KTX project of 100 cars of KTX-II contracted in June 2006, their target has been suggested from the previous RAMS application standard and it aimed to achieve the reliability level of equivalent high speed rolling stock. Afterward, as actual KTX-II RAMS Plan and RAMS Demonstration Plan has been prepared and approved, it has been the first problem to secure the reliability and safety in order to introduce the new high speed rolling stock(KTX-II) successfully and we actually tried to apply overseas RAMS standard, KTX samples, electric railcar MTRC and rolling stock samples. This Report was dealt world trends of Railway RAMS standard, KTX-II RAMS Specifications, the present condition of KTX-II RAMS performance and development a way of KTX-II RAMS, We hope the "KTX-II RAMS Application Standard for Safety of Passenger Transportation Service" is served as an opportunity for the basic research for establishing and demonstrating RAMS target of components or parts composing the rolling stock system.

• The Journal of the Acoustical Society of Korea
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• v.33 no.3
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• pp.153-162
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• 2014

Empirical prediction method of the acoustic load on the fairing is based on jet experimental data on the basis of similarity principle. Representative empirical prediction method, DSM-II(Distributed Source Method-II), is a distributing source method along the jet plume. But the empirical prediction model is limited to reflect the impingement source in real environment because it is based on the free jet data. So, we propose a empirical prediction method considering the impinging jet effect by adding a impingement source in the existing prediction method. Considering the additional source's displacement, spectrum, strength and directivity, we calculate the acoustic load on the KSR-III(Korean Sounding Rocket-III) rocket and compare the results with the existing method and experiment data.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.207-210
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• 2009

This paper presents development status of sounding rockets containing scientific payload and telemetry at home and abroad. The case of outside, united state is launching sounding rockets in 20-30 flight per year by the NASA program which offer to carry payload weights of 38-680 kg and altitude of 88-1,500 km. Europe is launching in 4-5 flight per year by the ESA program. Japanese sounding rockets are being applied an Antarctic exploration and flight verification in 1-2 flight per year. The case of korean sounding rockets was successful with the launch of three times(KSR-I,II,III), but our development techniques for space launch vehicle lag behind other industries. Therefore, Launch vehicle development should enable with the support and acquirement of advanced technology.

• Journal of Korea Technology Innovation Society
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• v.3 no.2
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• pp.61-77
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• 2000

우리 나라는 90년대에 들어서 향후 2015년까지 세계 10위권의 선진우주국에 진입한다는 우주개발중장기목표를 설정하고 중간 추진단계로서 2005년까지 국내기술에 의한 저궤도위성 및 발사체를 개발한다는 목표를 세우고 있다. 그리고 이를 위한 구체적인 시행 프로그램으로서 KSR-I및 KSR-II사업을 추진하여 성공적으로 완료하였으며, 이제 2002년까지 KSR-III사업으로 3단형 액체추진로켓을 개발 중에 있다. 현재 세계 우주 발사체 시장은 저궤도위성의 수요가 급증함으로서 전 세계적으로 저가의 우주발사체 개발을 서두르고 있으며, 우주선진국들은 경쟁적으로 기술혁신을 추진하고 있다. 그러나 개발도상국가들이 이에 참여하는데 있어서는 G7선진국들이 이미 마련한 MTCR(Missile Technology Control Regime)규제에 의거 기술이전 및 부품수입이 어렵기 때문에 자력에 의한 발사체 개발이 불가피하다. 본 고에서는 우주발사체 주요 선개발국 8개국의 기술혁신 과정과 정책 및 추진체계 등을 분석하고, 국내 발사체 개발에 참여하고 있는 주요 7개 민간기업을 대상으로 실시한 설문조사와 현장 실태조사를 바탕으로 기술혁신을 촉진하는 구체적인 정책대안 및 목표년도에 성공적인 발사를 위한 개선방안을 제시하였다.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.45-57
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• 2007

During the design phase of a system, which requires high reliability and safety such as aircraft, high speed train and nuclear power plant, reliability engineer must set up the target system reliability. To meet a reliability goal for the system, reliability allocation should be done gradually from the system to its element. For this end, first of all, we need to construct functional block diagram based on the design output and PWBS(Project Work Breakdown System). Another important input data for reliability allocation is the relationship between the cost and the reliability. In this study we investigate various reliability allocation models, which can be applicable to aircraft, vehicle, and power plant, and etc. And we suggest a proper reliability allocation model which can be effectively applicable to KTX-II high speed train to achieve the target system reliability.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.505-510
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• 2007

Concrete track will be constructed in Gyungbu High Speed Railway II(GHSR II) stage construction site from Daegu to Busan. Concrete track is supported by substructure consisting of the original ground and embankment and does not allow the settlement of track because of its structural type. The embankment is composed of rock and soil mixture and settlement is feasible. So management of settlement of embankment is key point in successful construction of the concrete track. Compaction management of mixed fill materials is important in minimizing the settlement of embankment. In this study, in order to assess the compaction characteristics of mixed fill materials, large laboratory compaction tests were conducted. Mixed fill materials were obtained from two construction sites in GHSR II construction site. Modeled mixed fill materials having different rock type, fine content, maximum particle diameter, and moisture contents were prepared. From the test results, compaction characteristics of mixed fill materials were analysed.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.499-504
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• 2003

Harmonic current originating from electric locomotives can be magnified due to the impedance characteristics of power supply circuit and bring about various problems. That is, electromagnetic interference with communication lines, operational trouble in signaling, overheat and/or vibration in power capacitor, mis-operation in protection relay and so on. Therefore, the exact assessment of the harmonic current flow must be undertaken at design and planning stage for the electric traction systems. For these reasons, this study propose a new approach to model and to analyse traction power feeding system focused on system response to current and voltage harmonic(PART I ). Measurements of harmonics are also performed for railway power supply systems under normal operation. Spectrum and distortion analyses in measurement data are variously described in PART II