• Journal of the Korean Society for Railway
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• v.13 no.1
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• pp.51-57
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• 2010

The aerodynamic drag of ultra high-speed train in evacuated tube have been calculated using computational fluid dynamics and the variation of aerodynamic drag for the change of major system parameter of tube-vehicle system such as the train speed, air density, and the tunnel diameter. The aerodynamic drag in the tube increases with increasing train speed, however, the ratio of drag increase in tube is larger than that on the open field, the V square rule. The aerodynamic drag decreases with increasing tunnel diameter and increasing air density, and the drag increasing for air density is almost linear just like that on open field. For some combination of the parameters, the trend of aerodynamic drag of train showed irregularity.

• Journal of the Korean Society for Railway
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• v.13 no.1
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• pp.44-50
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• 2010

This study is devoted to understand the basic characteristics of the flowfield around a train in evacuated tube and to suggest an efficient numerical method to calculate the flowfield. To get steady-state solution in minimum calculation domain, various boundary condition have been tried for steady calculation and have been compared to the solution of unsteady calculation. At the train velocity of 300km/h, the aerodynamic drag results of both calculation method agreed very well. The drag ratio between on the open filed and in the tube from the calculation result by the suggested numerical method lied in the same fitting curve with that from the filed test of high-speed trains running in the line.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1157-1161
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• 2011

Parametric study has been conducted to calculate the capacity of vacuum pump system that will be used to maintain the pressure of the tube system under atmosphere level. Recently many railroad researchers pay attention to the tube train system as one of the super high speed transportation system. To achieve the ultra super high speed, the inside of tube system should be maintained the low pressure level. In the low pressure environment, it is well known that air resistance of train is drastically decreased. Vacuum pump system will be used to make the low pressure level of tube system, exhaust the leakage air and supplement additional vacuum pumping. Qualitative and quantitative study has been conducted to review the effects of major parameters concerned with the capacity of vacuum pump system. As a results of these studies, we get the lump capacity of vacuum pump for various parameters. These results can be used to analyse the effects of the reduction of air resistance.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.61.1-61.1
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• 2013

최근 지구온난화 및 원유 공급 감소 또는 고갈로 에너지 효율성 높고 저탄소 녹색성장을 주도할 수 있는 철도산업에 대한 관심이 고조되고 있다. 초고속 자기부상철도는 에너지 효율이 높은 경제적인 교통수단으로써, 단위 수송당(인-km) 온실가스 배출량이 자동차의 38%, 항공기의 17%에 불과하고, 같은 궤도운송시스템인 고속철도에 비해서도 77%에 불과하고 단위수송당 에너지 소비율이 항공기의 80% 수준에 불과하므로, 화석에너지의 고갈이 예상되는 미래에 장거리 고속 이동 수단으로써 중요성이 확대되고 있다. 또한, 비접촉 추진 방식이므로 바퀴 접촉식 고속철도에 비해서 유지보수 비용이 저렴하고(34%에 불과) 고속철도에 비해 10dB 이상 소음 발생이 적은 수명주기 비용 및 환경측면에서 기존 철도시스템에 비해서 경쟁력이 있으므로 시급한 개발과 활용이 요구되고 있다. 본 연구에서는 초고속 자기부상철도 연구와 관련된 국내외 연구동향과 함께, 국가연구개발사업으로 추진중인 초고속 자기부상철도 핵심기술개발사업에 대해 살펴보았다. 또한, 미래기술로 각광을 받고 있는 튜브트레인 기술에 대해서도 알아보았다.

• Journal of the Korean Society for Railway
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• v.13 no.5
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• pp.516-520
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• 2010

Parametric study has been conducted to calculate the capacity of vacuum pump system that will be used to maintain the pressure of the tube structure under atmosphere level. Recently many railroad researchers pay attention to the tube train system as one of the super high speed transportation system. To achieve the super high speed, the inside of tube system should be maintained at low pressure level. In the low pressure environment, it is well known that air resistance of train is drastically decreased. Vacuum pump system will be used to make low pressure state for tube structure, exhaust the leakage air and supplement additional vacuum pumping. As results of these studies, we get the lump capacity of vacuum pump for various parameters. These results can be applied to analyze the effects of the reduction of air resistance.

• Journal of the Korean Society for Railway
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• v.14 no.2
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• pp.151-159
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• 2011

This study performed an experimental study for air-tightness performance evaluation of concrete tube structures with joints. The test specimens consist of a continuous concrete tube, a concrete tube with a joint in the middle, and a segmented concrete tube. The test is performed in such a way that the inner pressure of the tube is dropped down to 0.1atm and the increase of the pressure is monitored with time. An equivalent air permeability is then calculated based on the test results. The results show that, as expected, a structure with more joints or bonds tends to be less air-tight. A sensitivity study shows that the system air-tightness performance level becomes higher as either the diameter or the thickness of the tube increases. Moreover, the increase in the diameter or the thickness of the tube makes an effort to enhance the air-tightness more effective.

• Journal of the Korean Society for Railway
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• v.17 no.3
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• pp.186-192
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• 2014

In this paper, a reliability analysis is performed where the pressure change inside a concrete tube is probabilistically estimated considering the uncertainties inherent in the material and the system discontinuity. A set of uncertain quantities related to the equivalent system air permeability and the atmospheric pressure, are defined as random variables with specific distribution. The pressure change inside a concrete tube is then probabilistically described using both analytical and simulation approaches. The reliability analysis confirms that the geometric configuration of a concrete tube needs to be changed from the initial configuration obtained from the deterministic analysis.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1193_1194
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• 2009

일반적으로 자기부상열차는 고속, 내구성, 안전성 등을 만족하는 가장 적합한 시스템 중 하나로 부각되고 있다. 300[km/h] 이하의 중저속 자기부상철도의 경우, 추진용으로 선형유도전동기가 사용되고 있으며, 초고속 자기부상철도의 경우, 선형유도전동기보다 고효율, 고출력의 특성을 가지는 선형동기전동기가 사용되고 있다. 한국철도기술연구원에서는 2008년도부터 700[km/h]급 초고속튜브열차용 선형동기전동기연구를 시작하였으며, 추진/부상 일체형 권선형 선형동기전동기연구를 수행하고 있다. 따라서 본 논문에서는 초고속튜브열차용 선형동기전동기 연구의 일환으로, 축소형 영구자석형 선형동기전동기(PM-LSM)의 수학적 방법에 의한 기본설계를 수행하였으며, 이를 이동자만을 고려한 자기등가회로법을 이용하여 권선형 선형동기전동기(EM-LSM)로 변환 설계를 수행하였다. 또한 설계된 PM-LSM과 EM-LSM 모델의 FEM 해석을 이용한 특성 분석을 통하여 본 논문에서 제안한 변환 설계기법의 정확도 검증 연구를 수행하였다.

• Journal of the Korean Vacuum Society
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• v.16 no.2
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• pp.153-159
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• 2007

In-cryostat helium lines are under installation to transfer a cryogenic helium into cold components in KSTAR device. In KSTAR, three kinds of helium should be supplied into the cold components, which are supercritical helium Into superconduction(SC) magnet system, liquid helium into current lead system, and gas helium into thermal shields. Cryogenic helium lines consist of transfer lines outside the cryostat, in-cryostat helium lines, and electrical breaks. In-cryostat helium lines should be guaranteed of leak tightness for tong time operation at high internal helium pressure of 20 bar. We wrapped the helium line with multi-layer insulator(MLI) to reduce radiation heat and insulated the surface of the high potential part with prepreg tape. The electrical break was fabricated by brazing ceramic tube with stainless steel tube. To ensure the operation reliability at operation temperature, all the electrical break have been examined by the thermal cycle test at liquid nitrogen and by the hydraulic test at 30 bar. And additional surface insulation was prepared with prepreg tape to give structural safety. At present most of the in-cryostat helium lines have been installed and the final inspection test is progressing.