• 한국철도학회논문집
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• 제13권4호
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• pp.363-370
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• 2010

본 논문은 철도차량용 추진제어장치의 성능평가를 위한 관성부하 시험설비의 구조안전성 및 동특성 평가를 연구하였다. 추진제어장치는 철도차량의 핵심 부품으로서 차량에 적용하기 전에 안정성 및 신뢰성 검증이 충분히 이루어 져야 한다. 따라서 추진제어장치의 성능시험을 위한 관성부하 시험설비를 이론식을 바탕으로 하여 설계하였다. 설계된 관성부하 시험설비에 대해 Ansys v11.0을 이용하여 구조해석을 수행하였으며, ADAMS를 통해 동특성을 평가하였다. 관성부하 시험설비의 구조안전성은 조합하중하의 베어링에서 안전계수가 10.2로 만족하였다. 또한, 동적 시뮬레이션에 따른 플라이휠은 0.83mm이내의 최대진폭변위로 구조적 안정성이 확보되었다.

• Geomechanics and Engineering
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• 제34권3호
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• pp.303-316
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• 2023

With the development and utilization of urban underground space, the artificial ground freezing technology has been widely used in the construction of underground engineering in soft soil areas. The mechanical properties of soft clay changed greatly after freezing and thawing, which affected the seismic performance of underground structures. In this paper, a series of triaxial tests were carried out to study the dynamic response of the freezing-thawing clay under the seismic load considering different dynamic stress amplitudes and different confining pressures. The reduction factor of dynamic shear stress was determined to correct the amplitude of the seismic load. The deformation development mode, the stress-strain relationship and the energy dissipation behavior of the soft clay under the seismic load were analyzed. An empirical model for predicting accumulative plastic strain was proposed and validated considering the loading times, the confining pressures and the dynamic stress amplitudes. The relevant research results can provide a theoretical reference to the seismic design of underground structures in soft clay areas.

• 한국전산구조공학회논문집
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• 제27권5호
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• pp.421-427
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• 2014

현실세계의 구조물은 대부분 동하중의 영향을 받고 있지만, 구조해석이나 구조 최적화를 수행할 때는 정하중이 작용하는 것으로 가정한다. 실제 하중인 동하중을 고려하게 되면 다양한 하중들을 고려해야 하기 때문에 전산자원과 시간비용 측면에서 많은 제약이 따르기 때문이다. 그러나, 단순한 정하중 조건만을 고려하면 구조안전성 측면에서 바람직하지 못하기 때문에 가중치를 적용하거나 동하중을 대체하는 등가정하중을 적용하여 관련 문제를 보완하려는 연구가 진행되어 왔다. 본 연구에서는 등가정하중을 적용하여 동하중을 받고 있는 구조물에 대한 구조최적화 기법을 제안한다. 본 연구에서 적용하는 등가정하중은 기존 연구에서 제안한 바 있는 주자유도를 기반으로 하여 등가정하중 부과 위치를 결정하고 최적화 과정을 통해 산출한다. 이 과정에서 지나치게 큰 하중이 구해지지 않도록 가중치를 고려한 구속조건을 추가하여 기존 연구의 등가정하중의 최적화 과정을 보완하였다. 수치예제에서는 동하중이 작용하는 트러스 구조물과 평판 구조물에서 최적화된 등가정하중을 적용하여 사이즈 최적화를 수행함으로써 제안된 최적화 기법의 신뢰성을 검증한다.

• 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.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 추계 학술발표회 논문집
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• pp.189-196
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• 2002

The capacity of CFS piers has not been used to a practical design, because there is no guide of a seismic design for CFS piers. Therefore, the guide of a seismic design value is derived from tests of CFS piers in order to apply it to a practical seismic design. Steel piers and concrete-filled steel piers are tested with constant axial load using quasi-static cyclic lateral load to check ductile capacity and using the real Kobe ground motion of pseudo-dynamic test to verify seismic performance. The results prove that CFS piers have more satisfactory ductility and strength than steel piers and relatively large hysteretic damping in dynamic behaviors. The seismic performance of steel and CFS piers is quantified on the basis of the test results. These results are evaluated through comparison of both the response modification factor method by elastic response spectrum and the performance-based design method by capacity spectrum and demand spectrum using effective viscous damping. The response modification factor of CFS piers is presented to apply in seismic design on a basis of this evaluation for a seismic performance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 F
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• pp.2121-2123
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• 1998

In recent years, A PWM Converter or Switched Mode Converter with high power factor and sinusoidal input current have got widespread studied. But, Almost all of studies is based on linear load. This paper reports on research aimed at achieving high power factor and sinusoidal input current waveform for electronic arc welder, which has nonlinear dynamic characteristics. It is shown that simulation result yield its property.

• 한국가스학회지
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• 제12권1호
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• pp.1-6
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• 2008

샤피충격시험은 동적하중 하에 있는 고분자 재료의 거동을 이해하는데 가장 널리 사용되고 있는 방법이다. 본 연구에서는 샤피충격시험장치에서 얻어지는 파단에너지를 사용하여 나일론 소재 샤피 시편의 노치각도에 따른 에너지 해방율을 구하는 방법을 제시하였다. 또한 샤피충격시험장치를 계장화하여 최대 하중과 파단 시까지 소요되는 에너지 등의 파손인자들을 산출하였다. 그리고 노치각도에 따른 동적파괴 인성치와 유한요소법을 사용하여 중앙집중 하중 하에서 사피 시편의 노치각도에 따른 응력분포를 산출하였다.

• International Journal of Advanced Culture Technology
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• 제8권2호
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• pp.159-164
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• 2020

The response analysis of frame structure with open section beams considering warping conditions and short duration load have been performed. When a beam of frame structure is subjected under torsional moment, the cross section will deform a warping as well as twist. For some thin-walled sections warping will be large, and accompanying warping restraint will induce axial and shear stresses and reduce the twist of beam which stiffens the beam in torsion. Because of impact or blast loads, the wave propagation effects become increasingly important as load duration decreases. This paper presents that a warping restraint in finite element model effects the behavior of beam deformation, dynamic mode shape and response analysis. The computer modelling of frame is discussed in linear beam element model and linear thin shell element model, also presents a correlation between computer predicted and actual experimental results for static deflection, natural frequencies and mode shapes of frame. A method to estimate the number of normal modes that are important is discussed.

• 대한기계학회논문집A
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• 제24권6호
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• pp.1557-1564
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• 2000

When the half infinite crack in the orthotropic material strip with a large anisotropic ratio(E11>>E22) propagates with constant velocity, dynamic stress component $\sigma$y occurre d along the $\chi$ axis is derived by using the Fourier transformation and Wiener-Hopf technique, and the dynamic stress intensity factor is derived. The dynamic stress intensity factor depends on a crack velocity, mechanical properties and specimen hight. The normalized dynamic stress intensity factors approach the maximum values when normalized time(=Cs/a) is about 2. They have the constant values when the normalized time is greater than or equal to about 2, and decrease with increasing a/h(h: specimen hight, a: crack length) and the normalized crack propagation velocity( = c/Cs, Cs: shear wave velocity, c: crack propagation velocity).

• 한국지진공학회논문집
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• 제18권6호
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• pp.301-308
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• 2014

A suspension bridge is a type of bridge in which the beam is suspended by load-bearing cables. There are two classifications: the self-anchored suspension bridge has the main cable anchored to the bridge girders, and the earth-anchored suspension bridge has the main cable anchored to a large anchorage. Although a suspension bridge is structurally safe, it is prone to be damaged by various actions such as hurricanes, tsunamis and terrorist incidents because its cables are exposed. If damage to a cable eventually leads to the cable rupture, the bridge may collapse. To avoid these accidents, studies on the dynamic behavior of cable bridges due to the cable rupture have been carried out. Design codes specify that the calculated DAF (dynamic amplification factor) should not exceed a certain value. However, it has been difficult to determine DAFs effectively from dynamic analysis, and thus no systematic approach has been suggested. The current study provides a guideline to determine DAFs reliably from the dynamic analysis results and summarizes the results by applying the method to an earth-anchored suspension bridge. In the study, DAFs were calculated at the location of four structural parts, girders, pylons, main cable and hangers, with variations in the rupture time.