• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.934-939
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• 2004

The Korea high-speed rail, based on the French design. It also implements new concept to increase the strength of bridge deck by adding an impact factor (dynamic intensity factor) in static load. In order to assure the dynamic stability, SYSTRA and Jeseph Penzien, a professor in CEC (the US) conducted a dynamic stability review on design phase. Analyzing the review results, they developed design criteria for dynamic behavior. This study deal with operating PSC box GIRDER equipped with measurement equipment or measured data of Seoul $\∼$ Taejeon, P.S.C BOX GIRDER bridge and steel comsition bridge equipped with measurement equipment based on structual knowledge about configuration of measuring sensor, response analysis of structure when train runs was performed by using measured data of PSC box girder to directly compare with design criteria. moreover, the dynamic stability with comparison of high-speed rail construction criteria was reviewed and analyzed based on historical records.

• 한국철도학회논문집
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• 제12권4호
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• pp.574-581
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• 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
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• 제12권4호
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• pp.565-573
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• 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.

• 전자공학회논문지
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• 제50권12호
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• pp.56-62
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• 2013

우리는 MOSFET Layout 단계에서 Multiplier 구성을 통한 Common centroid layout 방식을 사용한 무선 전력 전송 용 CMOS 정류회로를 제안한다. 제안하는 정류회로는 기존의 다이오드를 사용하지 않은 Cross-coupled MOSFET 정류회로로 13.56 MHz에서 동작한다. 전력 소모를 최소화하고, 높은 주파수까지 동작하기 위하여 Full bridge 정류회로에서 효율을 높이기 위한 비교기를 제거하였다. Layout 단계에서 Multiplier 구성을 통한 Common centroid layout 방식은 Chip-layout 상에서 MOSFER의 Finger에 의해 길어진 연결 선로에 존재하는 기생 직렬 저항과 병렬 Capacitor에 의해 발생하는 시간 지연을 줄이기 위해 고안되어, 천이 시간을 줄여 Cross-coupled 구조의 On-상태에서 Off-상태, 혹은 그 반대의 상태 변화를 빠르게 한다. 이는 빠른 상태 변화 시간으로 인해 전력 변환 효율을 증가시킨다. 본 정류회로는 $0.11{\mu}m$ CMOS 공정으로 제작되었으며, 전력 변환 효율은 최대 86.4%로 측정되었으며, 600 MHz 이상까지 높은 전력 변환 효율을 가지며, 이는 현재 발표된 것 중, Cross-coupled 구성을 기반으로 한 정류회로 중 가장 높은 성능을 가진다.

• 한국강구조학회 논문집
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• 제11권2호통권39호
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• pp.223-232
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• 1999

도로상의 교량이나 기타구조물의 설계 및 유지관리를 위해서 도로상을 주행하는 중차량의 통행자료가 필요하다. 현재 국내에서 주로 이용되는 정적인 측정은 많은 시간과 인원이 필요하고 차종분포나 차간거리등은 수집할 수 없다. 특히 위치가 노출되어 신뢰성있는 자료을 얻지 못하는 단점이 있다. BWIM시스템은 교량을 이용하여 차량을 정지시키지않고 중량을 계측하는 시스템으로 정확하고 광범위한 자료를 얻을 수 있는 장치이다. 본 연구에서는 국내에서는 처음으로 BWIM시스템을 교량에 설치하여 그 적용성을 검증하고 시스템으로부터 얻어지는 여러 가지 자료를 분석하였다. 또한 과적검문소자료, Toll Gate자료 등 다른 방법에 의한 수집자료와 비교분석하여 일일교통량, 중량분포, 대표차량, 과적차량현황 등 여러가지 중차량의 통행특성들을 구하였다.

• Computers and Concrete
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• 제25권6호
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• pp.497-507
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• 2020

This paper presents a numerical method for evaluating fire performance of prestressed concrete (PC) T shaped bridge girders under combined effect of structural loading and hydrocarbon fire exposure conditions. A numerical model, developed using the computer program ANSYS, is employed to investigate fire response of PC T shaped bridge girders by taking into consideration structural inherent parameters, namely; arrangement of prestressing strands with in the girder section, thickness of concrete cover over prestressing strands, effective degree of prestress and content of prestressing strands. Then, a sequential thermo-mechanical analysis is performed to predict cross sectional temperature followed by mechanical response of T shaped bridge girders. The validity of the numerical model is established by comparing temperatures, deflections and failure time generated from fire tests. Through numerical studies, it is shown that thickness of concrete cover and arrangement of prestressing strands in girder section have significant influence on the fire resistance of PC T shaped bridge girders. Increase in effective degree of prestress in strands with triangular shaped layout and content in prestressing strands can slow down the progression of deflections in PC T shaped bridge girder towards the final stages of fire exposure, to thereby preventing sudden collapse of the girder. Rate of deflection based failure criterion governs failure in PC T shaped bridge girders under most hydrocarbon fire exposure conditions. Structural inherent parameters incorporated into sectional configuration can significantly enhance fire resistance of PC bridge girders; thus mitigating fire induced collapse of these bridge girders.

• Structural Engineering and Mechanics
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• 제77권3호
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• pp.343-354
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• 2021

The frequencies formulas of the bridge are of great importance in the design process since these formulas provide insight dynamic characteristics of the structure, which guides the designers to parametric analyses and the layout of the bridge in conceptual or preliminary design. Continuous rigid frame bridge is popular in the mountainous area. Mostly, this type of bridge was simplified either as a girder or cantilever when calculating the frequency, however, studies showed that the different configuration of the bridge made the problem more complex, and there is no unified fundamental calculation pattern for this kind of bridge. In this study, an empirical frequency equation is proposed as a function of pier's height, stiffness of pier and the weight of the structure. A unified fundamental frequency formula is presented based on the energy principle, then the typical continuous rigid frame bridge is investigated by finite element method (FEM) to study the dynamic characteristics of the structure, and then several key parameters are investigated on the effect of structural frequency. These parameters include the number, position and stiffness of the tie beam. Nonlinear regression analyses are conducted with a comprehensive statistical study from plenty of engineering structures. Finally, the proposed frequency equation is validated by field test results. The results show that the fundamental frequency of the continuous rigid frame bridge increases more than 15% when the tie beams are set, and it increases with the stiffness ratio of tie beam to pier. The results also show that the presented unified fundamental frequency has an error of 4.6% compared with the measured results. The investigation can predicate the approximate longitudinal fundamental frequency of continuous ridged frame bridge, which can provide reference for the seismic response and dynamic impact factor design of the pier.

• Structural Engineering and Mechanics
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• 제64권5호
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• pp.567-577
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• 2017

The traditional design procedure of a prestressed concrete (PC) cable-stayed bridge is complex and time-consuming. The designers have to repeatedly modify the configuration of the large number of design parameters to obtain a feasible design scheme which maybe not an economical design. In order to efficiently achieve an optimum design for PC cable-stayed bridges, a multi-parameter optimization technique is proposed. In this optimization technique, the number of prestressing tendons in girder is firstly set as one of design variables, as well as cable forces, cable areas and cross-section sizes of the girders and the towers. The stress and displacement constraints are simultaneously utilized to ensure the safety and serviceability of the structure. The target is to obtain the minimum cost design for a PC cable-stayed bridge. Finally, this optimization technique is carried out by a developed PC cable-stayed bridge optimization program involving the interaction of the parameterized automatically modeling program, the finite element structural analysis program and the optimization algorithm. A low-pylon PC cable-stayed bridge is selected as the example to test the proposed optimization technique. The optimum result verifies the capability and efficiency of the optimization technique, and the significance to optimize the number of prestressing tendons in the girder. The optimum design scheme obtained by the application can achieve a 24.03% reduction in cost, compared with the initial design.

• Journal of Power Electronics
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• 제14권6호
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• pp.1224-1232
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• 2014

A full-bridge secondary dual-resonant DC-DC converter using the asymmetrical pulse-width modulated (APWM) strategy is proposed in this paper. The proposed converter achieves zero-voltage switching for the power switches and zero-current switching for the rectifier diodes in the whole load range without the help of any auxiliary circuit. Given the use of the APWM strategy, a circulating current that exists in a traditional phase-shift full-bridge converter is eliminated. The voltage stress of secondary rectifier diodes in the proposed converter is also clamped to the output voltage. Thus, the existing voltage oscillation of diodes in traditional PSFB converters is eliminated. This paper presents the circuit configuration of the proposed converter and analyzes its operating principle. Experimental results of a 1 kW 385 V/48 V prototype are presented to verify the analysis results of the proposed converter.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권3호
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• pp.354-359
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• 2012

A transformerless converter suitable for multiphase drive application is presented in this paper. The topology employs a cascaded H-bridge rectifier as the interface between the grid and multi inverters which drive the multiphase motor. Compared with the conventional structure, the new topology eliminates the input transformer and also has the advantages such as four quadrant operation, simple configuration, low cost, high efficiency, and so on. The control strategies for the grid-side cascade H-bridge rectifier and the motor-side inverter are studied accordingly. Based on the multi-rotational reference frame, modular control scheme is developed to regulate the multiphase drive system. Simulation results show the proper operation of the proposed topology and the corresponding control strategy.