• Structural Engineering and Mechanics
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• 제27권4호
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• pp.501-521
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• 2007

This study presents a model to better understand the shear behavior of reinforced concrete walls subjected to lateral load. The scope of the study is limited to squat walls with height to length ratios not exceeding two, deformed in a double-curvature shape. This study is based on limited knowledge of the shear behavior of low-rise shear walls subjected to double-curvature bending. In this study, the wall ultimate strength is defined as the smaller of flexural and shear strengths. The flexural strength is calculated using a strength-of-material analysis, and the shear strength is predicted according to the softened strut-and-tie model. The corresponding lateral deflection of the walls is estimated by superposition of its flexibility sources of bending, shear and slip. The calculated results of the proposed procedure correlate reasonably well with previously reported experimental results.

• 한국구조물진단유지관리공학회 논문집
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• 제8권4호
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• pp.247-256
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• 2004

하층충격에 의한 2층 전단건물의 손상곡선을 엄계변위를 발생시키는 하중최대치 비와 임펄스 비를 이용하여 작성하였다. 손상곡선 작성에 필요한 구조물의 거동파악은 하중과 임펄스 응답행렬의 합성곱을 이용하여 구하였으며, 합성곱에 필요한 임펄스응답행렬은 모드중첩법을 이용하여 구하였다. 작성된 손상곡선으로부터 하층충격에 의한 각층의 안전성은 상층은 하중의 최대치에 그리고 하층은 임펄스의 크기에 민감한 것으로 파악되었다.

• 한국강구조학회 논문집
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• 제8권4호통권29호
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• pp.19-29
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• 1996

In this paper, it is presumed that the stress time history was generated by simulation method and investigated compatibility in regard to the reappearance of stress time history. In this procedure, the identified frequency distribution of stress range of the steel railroad bridge varies with the rational values of cut off point and bar width. Thus, we show variable aspect of the equivalent stress range results from change of cut off point and bar width. In addition, we analyze the variable of RMC and RMS model due to the cut off point and bar width of the measured stress history which influencs the prediction of fatigue life in the steel railroad bridge. The simulated stress time history is carried out by the superposition method incorporating the vertical load with rotation moment obtained from the Hermition interpolation function, and compared with developing stress results from measured maxi mum stress. Through this study, we can estimate the remaining fatigue life from a safety point of view and comparative accuracy.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1993년도 봄 학술발표회논문집
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• pp.37-44
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• 1993

There are a lot of linear dynamic analysis methods for complex structures. Each method has advantages and shortcomings. Method of dynamic analysis for complex structure is selected considering characteristics of dynamic loading, computer facility available number of degree of freedem and accuracy of results. It is a main point of view to get economical results rather then accurate ones for analysis of general complex structures, Mode superposition method and direct integration method are generally used. However, the characteristics of load is not considered in mode superpositon method, the personal computer cannot be used in direct integration methods. To over-come these shortcomings, the component mode method incorporating Ritz algorithm updated is proposed to solve economically dynamic behavior of the structures. The purpose of study is a formulation of algorithm, and computer programing suitable for dynamic analysis of the complex structure in personal computer environment.

• The Journal of the Acoustical Society of Korea
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• 제17권1E호
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• pp.70-75
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• 1998

The analysis of dynamic responses are carried out on several anisotropic systems due to buried pulsating line sources. These include infinite, semi-infinite spaces. The media possess orthotropic or higher symmetry. The load is in the from of a normal stress acting with parallel to symmetry axis on the plane of symmetry within the materials. The results are first derived for infinite media. Subsequently the results for semi-infinite are derived by using superposition of the solution in the infinite medium together with a scattered solution from the boundaries. The sum of both solutions has to satisfy stress free boundary conditions, thereby leading to the complete solutions. The solutions are simplified to the systems possessing of higher symmetry, such as orthotropic, transversely isotropic, cubic, and isotropic symmetry.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.96-101
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• 2004

When the wind blows hard, most waves are breaking in sea. Breaking waves occur, exceeding limitation of wave steepness(wave height/wave length=l/7). Because a wave of single angular frequency couldn't generate the breaking phenomena at two dimensional ocean engineering basin, the breaking wave can be generated by the superposition of waves with various angular frequencies. We research how are the particle kinematics in the breaking wave and the magnitude of the breaking wave exciting force. We compare the force in a regular wave which has same specifications(wave height, period and length) as the breaking wave. Also the experimental results of wave exciting force and particle velocity are investigated by comparison on the analytic results using the potential theory.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(I)
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• pp.490-496
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• 2002

This paper presents exact Autotransformers(ATs)-fed AC electric Railroad system modeling using constant current mode far locomotives. An AC electric railroad system is rapidly changing single-phase load, and at a feeding substation, 3-phase electric power is transferred to paired directional single-phase electric power. As the train moves along a section of line between two adjacent ATs. The proposed AC electric railroad system modeling method considers the line self-impedances and mutual-impedances. The constant current mode model objectives are to calculate the catenary and rail voltages with the loop equation. When there are more than one train in the AC electric railroad system, the principle of superposition applies and the only difference between the system analyses for one train. Finally, this paper shows the general equation of an AC electric railroad system, and that equation has no relation with trains number, trains position, and feeding distance.

• 대한전기학회논문지:전력기술부문A
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• 제52권9호
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• pp.493-499
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• 2003

This paper presents exact Autotransformers(ATs)-fed AC electric Railroad system modeling using constant current mode for locomotives. An AC electric railroad system is rapidly changing single-phase load, and at a feeding substation, 3-phase electric power is transferred to paired directional single-phase electric power. As the train moves along a section of line between two adjacent ATs. The proposed AC electric railroad system modeling method considers the line self-impedances and mutual-impedances. The constant current mode model objectives are to calculate the catenary and rail voltages with the loop equation. When there are more than one train in the AC electric railroad system, the principle of superposition applies and the only difference between the system analyses for one train. Filially, this paper shows the general equation of an AC electric railroad system, and that equation has no relation with trains number, trains position, and feeding distance.

• Composites Research
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• 제32권1호
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• pp.78-84
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• 2019

본 연구에서는 동적기계분석장치(dynamic mechanical analysis, DMA)와 시간-온도 중첩법(time-temperature superposition, TTS)을 이용하여 탄소섬유/에폭시 복합재의 장기 성능을 예측하고자 하였다. 이를 위해 단일 진동수 시험, 다중 진동수 시험, 크리프 TTS 시험을 수행하였다. 단일 진동수(single-frequency) 시험과 다중 진동수(multi-frequency) 시험에서는 $-30^{\circ}C$에서 $240^{\circ}C$까지 $2^{\circ}C/min$로 온도를 상승시키면서 $20{\mu}m$ 진폭의 사인(sine) 파형의 하중을 가하였으며 다중 진동수 시험에 적용된 진동수는 0.316, 1, 3.16, 10, 31.6 Hz이다. 크리프 TTS 시험에서는 $-30^{\circ}C$에서 $230^{\circ}C$까지 $10^{\circ}C$마다 15 MPa의 응력을 10분 동안 가하였다. 단일 진동수 시험을 통해 유리전이온도를 구하였으며 다중 진동수 시험을 통해 진동수 별 유리전이온도에서 활성화 에너지와 온도 별 저장탄성계수 선도를 구하였다. 또한 아레니우스 식(Arrhenius equation)을 통해 얻은 이동 인자를 적용하여 기준 온도에 대한 마스터 선도를 얻었다. 또한 크리프 TTS 시험을 통해서는 크리프 컴플라이언스 선도를 구하고 직접 이동 기법을 이용하여 구한 이동 인자를 적용하여 기준 온도에 대한 마스터 선도도 얻었다. 이와 같은 과정을 통해 얻은 마스터 선도를 이용하면 주어진 환경 조건에 대한 탄소섬유강화 복합재의 장기 성능을 예측할 수 있다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.3147-3155
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• 2011

Railway bridges are highly susceptible to resonance due to the equidistant axle load with constant speed of train. Thus, it is inevitable verify dynamic characteristics and quantities against dynamic guidelines. Recently, various new-type bridges are developed and applies to medium span length between 30m and 40m. However, just steel box girder bridge is under review for span length between 45m and 50m without development any new technologies. This study investigate the dynamic properties and safety of steel box railway bridge having span length 45m in alternative girder hight and kind of ballast. Numerical analysis is performed time series analysis by mode superposition using calculated natural vibration frequency and mode after carry out a free vibration analysis and extract modal parameter to higher modes. The results are then compared to various dynamic stability standards toward target bridge's dynamic stability analysis. The result of this study is expected as a reference for design railway bridges.