• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(II)
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• pp.826-833
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• 2002

In recent years, due to the continuous concentration of population and sharp increment of commuters around Seoul metropolitan area, traffic jam has become one of severe problems along with housing in this area. In oder to solve the problem like the one mentioned above, 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 train has weak points such as big cross sectional area and high mass center that cause unsafe vehicle running performances and interface problems between the vehicles and infrastructures. Therefore, prior to operate double deck trains on the existing lines, careful investigations should be performed. For these reasons, we have investigated foreign double deck trains and studied the technologies for a double deck train as an alternative way to carry heavy transportation efficiently and comfortably.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(II)
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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.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(III)
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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.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(III)
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• pp.91-97
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• 2003

In many countries such as Japan, France and so on, the number of double-deck trains has been dramatically increased for the purpose of public traffic. Several researchers have performed feasiblilty studies related to the operations of double deck rolling stock vehicles in Korea since 2001. In recent years, rolling stock vehicles are required to have light weight to save energy consumption and maintenance costs. For these reasons, the standard EMU vehicle developed by KRRI and Kwan-Ju EMU(Electric Multi Unit) are made of aluminum extruded panels. The concept model of a double-deck rolling stock vehicle investigated in this study is also designed to use AEP(Aluminum Extruded Panel). In this paper, the methods related to the structural strength improvements of the car body are proposed through careful modifications of thicknesses and shapes of AEP.

• 한국세라믹학회지
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• 제34권1호
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• pp.88-94
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• 1997

플라즈마 용사법(plasma spray method)으로 제작된 상용 가스 터빈 연소기의 finned segment의 열차폐용 코팅계, ZrO2-8wt%Y2O3 top coat/Ni-26Cr-5Al-0.5Y bond coat/Hastelloy X superalloy 기판에서 NiCrAlY bond coat의 산화 거동과 열피로 파괴에 대하여 조사하였다. 생성된 bond coat의 주산화물은 NiO, CrO2, Al2O3였다. ZrO2/bond coat계면에서 생성된 산화물의 분포는 고온에서의 사용 전에 이 계면 아래에 얇은 층의 Al2O3가없는 곳에서는 NiO 산화층 및에 Cr2O3와 Al2O3가 혼합된 형태를 나타내었다. 열피로에 의해 박리된 시편의 파면을 관찰한 결과, 파괴는 주로 ZrO2/산화층 계면보다 세라믹층내로 약간 치우쳐서 일어나지만, 산화층 내에서도 약간 일어남을 알 수 있었다.

• Journal of Welding and Joining
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• 제19권2호
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• pp.221-227
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• 2001

Based on the principle of complementary energy, an analytical method is developed which focuses on the end effects for determining thermal stress distributions in a three-layered beam. This method gives the stress distributions which completely satisfy the stress-free boundary conditions. A numerical example is given in order to verify this method. The results show that the present analytical solutions have the values of stress in excellent agreement with the solutions derived by other investigators. Using this method, the effects of the thickness of bond coat on the thermal stresses of a typical sprayed thermal barrier coating, which consists of IN738LC substrate, MCrAIY bond coat and ZrO$_2$-8wt%Y$_2$O$_3$top coat, were investigated.

• 한국재료학회지
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• 제8권6호
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• pp.538-544
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• 1998

열차폐코팅층의 박리는 세라믹/금속접합층 계면에서 취성이 큰 스피텔의 생성, 금속과 세라믹의 열팽창계수의 차이, 세라믹층의 상변태, 코팅층의 잔류응력에 기인한다. 본 연구에서는 인코넬 713C에 전자빔 코팅 및 플라즈마 용사법으로 코팅된 안정화지르코니아/CoNiCrAIY 계면의 산화거동을 조사하기 위하여 $900^{\circ}C$에서 등온산화시험동안 생성되는 산화막층과 스피넬 생성 거동을 관찰, 분석하였다. 코팅 직후 코팅층에 고르게 분포하고 있는 Co,Ni,Cr,AI,Zr의 원소들이 산화시간에 따라 확산하여 산화반응을 하였다. 초기 20시간의 산화기시간에 안정화지르코니아/CoNiCrAIY 계면에 주요 성분이 $\alpha$-$AI_2O_3$인 산화막층이 생성되었고, CoNiCrAIY층에는 AI의 외부확산으로 인한 AI 결핍지역이 생성되었다. 산화시험동안 $\alpha$-AI2O층이 임계두께까지 성장한 후에 산화막층의 성장속도는 감소하였고, 안정화지르코니아/산화막층 계면에 스피넬, $Cr_2O_3$, $CO_2CrO_4$의 형성으로 인한 크랙이 관찰되었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.387-392
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• 2005

Double-deck train have studied in the next generation train in KRRI. Double-deck train have more seat capacities compared with single deck vehicles and is a efficient, reliable and comfortable alternative train. Because of heavy weight, weight minimization of double-deck train carbody is imperative to reduce cost and extend life-time of train. Weight minimization problem of the double-deck train car-body is required to decide 66 design variables of thicknesses for large aluminum extruded panel while satisfying stress constraints. Design variables are too many and one execution of structural analysis of double-deck train carbody is time-consuming. Therefore, we adopt approximation technique to save computational cost of optimization process. Metamodels such as response surface model (RSM) and kriging model are used to approximate model-based optimization is described. RSM is easy to obtain and expressed explicit function, but this is not suitable for highly nonlinear and large scaled problems. Kriging model employs an interpolation scheme and is developed in the fields of spatial statistics and geostatistics. Target of this design is to find optimum thickness of AEP to minimize weight of doulbe-deck train carbody. In this study, meta model techniques are introduced to carry out weight minimization of a double-deck train car-body.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.748-753
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• 2004

Aluminum alloy is very useful material for high speed transportations due to its high strength and light weight characteristics. Especially because of a weight reduction a large extrustion of aluminum alloy carbody has been manufactured. This aluminum extruded panel is a hallow extruded panel. This shape and thickness is various by designer's sense and experience and VAW's profiles. So it is important to find an optimized shape and thickness of AEP. In this study we get the AEP's thickness to minimize a weight by applying an applying an optimization algorithm. The results of the study can be used as basic guidelines double-deck trains in the future.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 춘계학술대회 논문집
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• pp.364-369
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• 2002

The purpose of this paper is to introduce the concept design and the structural strength of the double-deck rolling stock vehicle. Aluminum is very useful material for the carbody structure due to its characteristic of light weight. Large alumillum extrusion profiles(panels) have toe of merits such as easy production of complicated shapes, reduction of welding and cutting lines, and cutting down the labor cost. AED type is being applied to the standard EMUs and the EMUs Kwangju subway in Korea. Light material recommended the double-deck rolling stock vehicle because the center of gravity of the train is higher and its weight is heavier than those of the normal vehicle. So we applied the technology of the large aluminum extrusion profiles(panels) to the double-deck vehicle. We performed the structural strength analysis and examined its safety.