• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.413-420
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• 2003

In this paper an analytical study is carried out to examine the effectiveness of absorbing boundaries using dashpot. Validity of the absorbing boundary conditions suggested by Lysmer-Kuhlemeyer and White et al. is investigated by adopting the solution of Miller and Pursey. The Miller and Pursey's problem is then numerically simulated using the finite element method. The absorption ratios are calculated by comparing the displacements at the absorbing boundary to those at the free field without the absorbing boundary. The numerical verification is carried out through comparison of displacement at the boundary.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.866-871
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• 2005

In this paper a study on the characteristics and the reduction method for the ground vibration due to traveling tilting car is carried out. The transmitted load which induces the ground vibration is computed through a study oil the interaction between tilting car and the line. Then, this lead is applied into the numerical model, which is not only designed considering the diverse ground conditions hut also verified by the ultrasonic experiment. Through the numerical analysis according to the conditions, the characteristics and the reduction method for the ground vibration by tilting car are studied.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.04a
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• pp.109-118
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• 1999

Lifeline system such as oil or gas pipelines and water supply facilities are vulneratble to seismic damages because they are widely exposed to ground failures. Most seismic design criteria of buried pipelines are based on the notion that the longitudinal compressive strain and therefore buckling controls the design. Buckling analysis of buried pipelines subjected to seismic loading is performed by considering the seismic load as the sinusoidally distributed compressive load on the beam on elastic foundation in contrast to existing studies where the buckling load is treated as an end load on the beam column, An approximated analytical solution is obtained by the energy method and its validity is confirmed by the linearized finite element buckling analysis. The results show the beam mode buckling because longitudinal strains at the buckling loads are substantially lower than the strain at the onset of local buckling.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.174-181
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• 2002

The paper presents an effective analytical method for SSI systems which can have separation or sliding at the soil-structure interface. The method is based on a hybrid approach which combines a linear SSI code KIESSI-2D in frequency domain with a commercial finite element package ANSYS to obtain nonlinear dynamic responses in time domain. The method is applied to a 2-D underground box structure which experiences separation and sliding at the soil-structure interface. Material nonlinearity of the concrete structure is also included in the analysis. Effects of the interface conditions are examined and some critical factors affecting the seismic performance of underground structures are identified.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.133-136
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• 2010

공간부족과 해안 매립으로 발생되는 문제점을 해결하기 위하여 초대형부유구조물이 각광 받고 있으며, 대표적인 구조형식으로는 폰톤식과 반잠수식이 있다. 하지만 다양한 환경에 적용하기에는 구조적으로 한계를 가지고 있으며, 이를 극복하기 위해 부유체 하부에 수직으로 결합된 실린더에 공기를 가두어 지지되는 공기안정식 플랫폼이 제안되어졌으나 아직 개념단계에 머무르고 있는 실정이다. 이에 본 연구에서는 공기 안정식 초대형부유구조물의 실린더 내부 공기상태에 따른 안정성을 검토하기 위하여 유체정역학적 관계를 통해 실린더 내부의 공기 복원력 변수를 산정하였으며, 선형파랑하중에 따른 구조물의 응답을 최소화 할 수 있는 변수의 범위를 제시하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.578-581
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• 2004

In this paper numerical and experimental studies are conducted to examine the wave screening effectiveness of wave barriers. The numerical study is based on a finite element model of a 'sandbox' with Lysmer-Kuhlemeyer-type absorbing boundaries. Using the model, the screening effectiveness of wave barriers is studied for different barrier dimensions and distances between the source/receiver and the wave barrier. The results of the numerical modeling are compared with those of the ultrasonic experiment which is performed on an acrylic block with a drilled rectangular cut. Finally, the problem of ground transmitting vibration from a traveling train is numerically treated as a real-world application and the results are discussed in some detail.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.376-383
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• 2003

For more rational and economical seismic design of long span bridges, it is essential to include in the analysis the effects of multiple input motions and structural or soil nonlinearity which are not considered in the current design practice. In this paper, the effects of these factors on the seismic behavior of long span bridges are studied. First, for the effect of multiple input motions, we take into account the differences in arrival times of seismic waves. To consider nonlinear soil properties we utilize SHAKE which is based on the equivalent linearization method. As a numerical example, a cable-stayed bridge is modelled using the analytical procedures described above. It is shown from the results that the these factors influence the seismic response of the bridge significantly and should never be neglected in design.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.505-512
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• 2003

As large structures such as highrise buildings and cable-stayed bridges become lighter and more flexible, the necessity of structural control for reducing excessive displacement and acceleration due to seismic excitation is increased. As a means to minimize seismic damages, various base isolation systems are adopted or considered for adoption. In this study, the seismic performance of M dampers are studied and compared with that of the NZ system as a base isolation system As the control algorithm of the MR damper, the clipped-optimal control(applied LQR method) is employed. A five-story building is modeled and the seismic performance of the two systems subjected to three different earthquakes is compared. The results show that the M damper system can provide superior protection than the NZ system for a wide range of ground motions.

• Journal of the KSME
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• v.28 no.2
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• pp.146-149
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• 1988

19세기의 기술시대 이후, 20세기 전반은 과학의 시대, 20세기 후반은 과학과 공학이 연합한 세 련된 기술의 창조시대였으며, 21세기는 정교한 공학과 과학의 지식이 요구되는 시대라고 한다. 이러한 논리는 현대공학이 기술주도와 과학주도 공학분야의 결합체로서, 공학적 수련(engineering practice)을 위해서는 과학이 원리에 기본을 둔 지시과 수련과 기술에 의하여 주도된 경험적 지 식을 모두 요구하고 있기 때문이다. 공학은 응용과학과는 다르며 과학적인 원리와 경험적 지 식을 사용하여 기술적인 해를 추구하는 방법임에도 불구하고 오늘날의 세계적인 공학교육의 추 세는 아직까지도 과학적 원리에 중점을 두어왔으며, 따라서 공학의 요체라 할 수 있는 수련과 기술에 의한 경험적 지식은 대학교육에서 도외시 되어온 반면, 많은 부분이 산업체에 축적, 존 재하게 되었다. 특히 현대의 고도기술 경쟁사회에 있어서 창의적 기술개발은 상대적 기술우위를 점하기 위해 필수적인 요소가 되고 있으며 '기술에는 과거가 있어도 기술자에게는 과거가 없고 오직 미래만이 있다'는 아이러니가 통용되고 있는 실정이다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.7 no.1
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• pp.1-9
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• 1989

Up to date, the ditermination of three dimentional position is performed sperately by horizontal and vertical adjustment. The purpose of this study is to determine simultaneously three dimentional coordinates of one unknown point by measuring only three slope distances from one unknown point to three fixed points. In this study, the adjustment problem for measurement values inclading redundancy is solved by observation equation and condition equation, and also the characteristic of these two analysis methods is studied and investigated.