• Journal of Electrical Engineering and Technology
• /
• 제9권3호
• /
• pp.888-892
• /
• 2014

In the design of the rotor of an interior permanent magnet synchronous motor (IPMSM), the bridge between the permanent magnets helps prevent the scattering of permanent magnets and pole pieces during high-speed operation. In the design of a motor, if the bridge is too thick, its performance will be largely degraded because of flux leakage. Additionally, if the bridge is too thin, its mechanical safety cannot be guaranteed. Thus, an accurate analysis method is required to determine the thickness of the bridge. Conventional stress analysis methods determine the thickness of the bridge by only considering the centrifugal force of the rotors. In this study, however, a method that additionally considers the radial force generated by the air-gap flux density based on the conventional methods is proposed and reflected in the design of a traction motor for electric vehicles. Finally, the validity of this study is verified through a reliability test related to high-speed operation.

• Structural Engineering and Mechanics
• /
• 제34권2호
• /
• pp.213-229
• /
• 2010

An analytical method is proposed for the evaluation of the static response of a prestresse-dribbon concrete pedestrian bridge, which may also be applied for the roofing of large areas. On the basis of an established analogy with a suspension bridge system, a procedure is presented for the prestresse-dribbon direct analysis, leading to the introduction of two dimensionless parameters as governing factors of the design, namely the thinness and the prestressing steel ratio. The exposed procedure, applied by a simple computer program, allows a quick evaluation of the response and permits the investigation of the influence of the aforementioned parameters on it, by means of comprehensive diagrams. The presented diagrams may be directly used for the preliminary design of a pedestrian bridge of this type, for the whole practical range of span lengths. A design example is also included, showing the applicability of the proposed procedure.

• 한국철도학회논문집
• /
• 제12권4호
• /
• pp.574-581
• /
• 2009

장대레일이 교량구간에 설치되면, 궤도와 교량의 상호작용에 의하여 부가축력과 변위가 발생하게 되므로 설계단계에서 장대레일의 부가축력 및 변위 검토가 필요하다. 본 논문에서는 장대레일 상호작용에 영향을 미치는 주요 인자들을 변수로 종방향 상호작용해석을 수행하였으며, 교량설계단계에서 장대레일 부가축력 및 변위 검토를 간단히 수행할 수 있도록 설계차트로 정리하였다. 본 논문에 제시된 설계차트는 일반철도 교량에 대한 결과로써, 강교량 및 콘크리트 교량, 지갈궤도 및 콘크리트궤도, 단순교(FM방식) 및 연속교(MFM방식)에 대하여 하부강성 및 상부강성별 설계차트로 구분하여 제시되었다.

• 한국철도학회논문집
• /
• 제12권4호
• /
• pp.565-573
• /
• 2009

장대레일이 교량구간에 설치되면, 궤도와 교량의 상호작용에 의하여 부가축력과 변위가 발생하게 되므로 설계단계에서 장대레일의 부가축력 및 변위 검토가 필요하다. 본 논문에서는 장대레일 상호작용에 영향을 미치는 주요 인자들을 변수로 종방향 상호작용해석을 수행하였으며, 교량설계단계에서 장대레일 부가축력 및 변위 검토를 간단히 수행할 수 있도록 설계차트로 정리하였다. 본 논문에 제시된 설계차트는 고속철도 교량에 대한 결과로써, 강교량 및 콘크리트 교량, 자갈궤도 및 콘크리트궤도, 단순교(FM방식) 및 연속교(MFM방식)에 대하여 하부강성 및 상부강성별 설계차트로 구분하여 제시되었다.

• 대한토목학회논문집
• /
• 제26권1A호
• /
• pp.11-19
• /
• 2006

본 연구에서는 현수교의 선박충돌해석을 위한 설계선박을 결정하기 위하여 선박충돌위험도해석을 수행한다. 선박충돌에 대한 설계선박을 결정하기 위하여 AASHTO 설계기준에서 제시한 3개의 선박충돌 설계방법 중 확률기반 해석방법인 Method II를 사용한다. 선박충돌 위험에 노출된 각각의 교각에 대해 선박충돌위험도 평가를 하여 교각의 충돌설계수평강도를 결정한다. 해석과정은 반복적인 것으로 교량부재의 충돌저항강도를 가정하고 연간파괴빈도를 계산하여 허용기준이 만족하도록 설계 변수를 수정한다. 허용기준은 예상연간파괴빈도에 근거한 가중치를 이용하여 교각에 할당한다. 해석결과에서 안전성과 경제성을 얻기 위해 이 할당방법을 주탑집중 할당방법과 비교한다. 비록 주탑집중 할당방법이 주탑에 비해 과대평가되는 교각의 설계수평강도를 적절히 수정할 경우 보다 경제적인 결과를 가져오지만, 가중치에 의한 할당방법이 설계인자의 특성을 정량적으로 고려하기 때문에 더 합리적인 것으로 보인다. 그리고 선박충돌위험도 평가로부터 얻어지는 충돌설계수평강도에 상응하는 각각의 교각에 대한 설계선박이 결정된다. 같은 교량에 대해서도 충돌설계수평강도가 수로 및 교량의 특성과 선박통행량에 따라 상당히 변화한다. 따라서 허용기준의 할당과 설계선박 선정에 대한 많은 연구가 요구된다.

• 기술사
• /
• 제39권6호
• /
• pp.42-48
• /
• 2006

This is briefly to introduce about design and construction method newly adopted in Incheon bridge construction site. The Incheon Bridge Project are divided into 3 parts, that is Cable Stayed Bridge. Viaduct Bridge and Approach Bridge. In this paper, we will describe overview and construction sequence of each kind part.

• Wind and Structures
• /
• 제13권4호
• /
• pp.309-326
• /
• 2010

CFD techniques try to find their way in the bridge engineering realm nowadays. However, there are certain fields where they offer superior performance such as conceptual bridge design and bidding design. The CFD studies carried out for the conceptual design of a 425 m length cable-stayed bridge are presented. A CFD commercial package has been employed to obtain for a set of cross-sections the aerodynamic coefficients considering 2D steady state. Additionally, for those cross-sections which showed adequate force coefficients, unsteady 2D simulations were carried out to detect the risk of vortex shedding. Based upon these computations the effect on the aerodynamic behavior of the deck cross-section caused by a number of modifications has been evaluated. As a consequence, a new more feasible cross-section design has been proposed. Nevertheless, if the design process proceeds to a more detailed step a comprehensive set of studies, comprising extensive wind tunnel tests, are required to better find out the aerodynamic bridge behavior.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2010년도 춘계학술대회 논문집
• /
• pp.1691-1696
• /
• 2010

Jeong-Ji overbridge is designed to be 9.3km long, the longest for a high speed railway bridge ever constructed in Korea. This bridge is constituted of three types of structure. Standard type bridge is 35m PSC Box bridge which will be constructed by Precast Span Method. To cross the Cheonan Nonsan Expressway, 80m three-span steel arch bridge is designed to avoid rail expansion joint. Finally, Extradosed bridge is planned for high speed railway bridge for the first time in Korea based on originative and advanced design techniques. It is expected that this will contribute to the development of national technology for long-span high speed railway bridges.

• International Journal of Railway
• /
• 제8권1호
• /
• pp.5-9
• /
• 2015

Reliability based limit state design method is replacing traditional deterministic designs such as allowable stress design and/or ultimate strength design methods in world trends. European design code(Eurocode) has adopted limit state design, and Korea road bridge design standard has also recently been transferred to limit state design method. In this trend, Korea railroad design standard is also preparing for adopting the same design concept. While safety factors are determined empirically in traditional design, load combinations as well as load factors are determined by solving limit state equations. General partial safety factors are evaluated by using AFORM(Advanced First Order Reliability Method) in the reliability based limit state design method. In this study sensitivity analysis is carried out for a dead load factor and a live load factor. Relative precisions of the dead load and the live load factors are discussed prior to the AFORM analysis. Furthermore the sectional forces of design and the material quantities required by two different design methods are compared for a PSC box girder railway bridge.

• Structural Engineering and Mechanics
• /
• 제5권4호
• /
• pp.399-414
• /
• 1997

This paper presents an investigation into the seismic response characteristics of a proposed ligh-weight pedestrian cable-stayed bridge made entirely from Glass Fiber Reinforced Plastics(GFRP). The study employs three dimensional finite element models to study and compare the dynamic characteristics and the seismic response of the GFRP bridge to a conventional Steel-Concrete (SC) cable-stayed bridge alternative. The two bridges were subjected to three synthetic earthquakes that differ in the frequency content characteristics. The performance of the GFRP bridge was compared to that of the SC bridge by normalizing the live load and the seismic internal forces with respect to the dead load internal forces. The normalized seismically induced internal forces were compared to the normalized live load internal forces for each design alternative. The study shows that the design alternatives have different dynamic characteristics. The light GFRP alternative has more flexible deck motion in the lateral direction than the heavier SC alternative. While the SC alternative has more vertical deck modes than the GFRP alternative, it has less lateral deck modes than the GFRP alternative in the studied frequency range. The GFRP towers are more flexible in the lateral direction than the SC towers. The GFRP bridge tower attracted less normalized base shear force than the SC bridge towers. However, earthquakes, with peak acceleration of only 0.1 g, and with a variety of frequency content could induce high enough seismic internal forces at the tower bases of the GFRP cable-stayed bridge to govern the structural design of such bridge. Careful seismic analysis, design, and detailing of the tower connections are required to achieve satisfactory seismic performance of GFRP long span bridges.