• 한국안전학회지
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• 제23권2호
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• pp.7-13
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• 2008

In a long-span bridge which is constructed on soft soil, it is requested to make a plan considering soil-structure interaction, and soil-structure interaction is partially under consideration at the actual bridge plan. Many researches on dynamic behavior of a bridge affected by soil-structure interacting have been accomplished, but it is difficult to estimate dynamic behavior of a bridge on soft soil accurately because of many uncertainties. This paper presents the results about dynamic response of a long-span suspension bridge in the site composed of soft soil considering incident angle of input ground motion. The effect of soft soil was evaluated by the use o computer program SASSI and a long-span suspension bridge was modeled by finite element program MIDAS. The effect of incident angle of input ground motion was investigated on the dynamic response of a long-span bridge.

• 한국지반공학회논문집
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• 제22권4호
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• pp.105-111
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• 2006

본 연구에서는 먼저 지표면을 비롯하여 구조물 곳곳에 가속도계가 설치된 깊은 직접기초 구조물 2개를 선정하였다. 이어서 구조물에 기록된 실지진 데이터를 사용하여 주파수 영역에서 Transmissibility 함수를 사용하는 기법으로 기초 위치에서와 자유지표면에서의 지반운동 사이의 차이를 산정하였고 실지진기록을 사용하여 산정된 이 변환함수를 기존의 간편식과 비교하여 검증하였다. 비록 강성 기초저면, 연직으로 전파되는 지반운동을 가정하는 간편식의 전제조건은 실제 조건과 차이가 있지만, 그럼에도 불구하고 실지진기록으로부터 산정된 변환함수와 매우 양호한 유사성을 보여주므로 간편식을 설계실무에서 사용할 수 있을 것으로 판단된다.

• 한국소음진동공학회논문집
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• 제15권7호
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• pp.806-812
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• 2005

This paper adresses the shaking table tests with 1/100 scaled model followed similitude law for OOdam main designing section to understand nonlinear behavior characteristics of concrete dam body by ground motion. As earthquake wave, Hachinohe and El Centre waves were used and acceleration and displacements are measured to analyze behaviors of dam body. For maximum ground acceleration range $(0.3\~0.9 g)$, the results showed linear behavior regardless of maximum 9round acceleration and secured safety of structure. To analyze the behavior of dam after tension cracking, 3 cm-notch was placed at the critical section of over-flowing section. As results of applying Hachinohe wave(0.8 g), Even though tension cracks were formed at over-flowing section by Hachinohe wave(0.8 g), it showed that the dam is stable for supporting upper stream Part of water tank of dam.

• Journal of Biosystems Engineering
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• 제12권3호
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• pp.17-29
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• 1987

A 10-degree of freedom mathematical model of motion for power tiller-trailer system was developed. This model can predict motion characteristics of power tiller trailer system while travelling over smooth and irregular ground surfaces under various operating conditions. The model provide, the fundamental data needed to improve the stability of power tiller-trailer systems.

• 한국지진공학회논문집
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• 제20권7_spc호
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• pp.435-441
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• 2016

The Korean peninsula has known as a minor-to-moderate seismic region. However, some recent studies had shown that the maximum possible earthquake magnitude in the region is approximately 6.3-6.5. Therefore, a seismic vulnerability assessment of the existing infrastructures considering ground motions in Korea is necessary. In this study, we developed seismic fragility curves for a continuous steel box girder bridge and two typical transmission towers, in which a set of seven artificial and natural ground motions recorded in South Korea is used. A finite element simulation framework, OpenSees, is utilized to perform nonlinear time history analyses of the bridge and a commercial software, SAP2000, is used to perform time history analyses of the transmission towers. The fragility curves based on Korean ground motions were then compared with the fragility curves generated using worldwide ground motions to evaluate the effect of the two ground motion groups on the seismic fragility curves of the structures. The results show that both non-isolated and base-isolated bridges are less vulnerable to the Korean ground motions than to worldwide earthquakes. Similarly to the bridge case, the transmission towers are safer during Korean motions than that under worldwide earthquakes in terms of fragility functions.

• 한국지진공학회논문집
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• 제7권4호
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• pp.23-30
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• 2003

최근 수행된 우리나라 원전 부지에 대한 지진재해도 해석 결과 작성된 등재해도 스펙트럼에서 고진동수 성분의 지진동이 매우 우세하게 나타나고 있다. 일반적으로 지진취약도 해석에서는 설계 스펙트럼에 내재된 보수성을 평가하기 위해 스펙트럼 형상계수가 사용된다. 본 연구에서는 입력지반운동 스펙트럼의 형상이 변화함에 따른 층응답스펙트럼의 형상 변화를 분석하였다. 이때 입력 스펙트럼으로부터 직접 층응답스펙트럼을 작성할 수 있는 직접법을 사용하였다. 본 연구 결과 건물 내부에 설치된 기기의 취약도해석에서는 입력스펙트럼에 내재된 보수성을 구조물의 고유진동수에 대한 스펙트럼 형상계수가 아닌 기기의 고유진동수에 따른 층응답스펙트럼 형상계수로 고려하는 것이 정확한 취약도해석 결과를 주는 것으로 나타났다.

• 자원환경지질
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• 제31권1호
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• pp.53-57
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• 1998

Transient electromagnetic (TEM) method is also affected by cultural and natural electromagnetic (EM) noises, since it uses part of the broadband ($10^{-2}$ to $10^5Hz$) spectrum. Especially, predominant EM noise which affects a moving transmitter-receiver TEM system is sensor motion-induced noise. This noise is caused by the sensor motion in the earth magnetic field. The technique for reducing the sensor motion-induced EM noise presented in this paper is based on Halverson stacking. This Halverson stacking is generally used in a time-domain induced polarisation (IP) system to reject DC offset and linear drift. According to spectrum analysis of the vertical component of sensor motion-induced noise, the frequency range affected by the motion of an EM sensor is less than about 700 Hz in this study. With the decrease of the frequency, the spectral power caused by the motion of a sensor increases. For example, at the frequency of 200 Hz, the spectral power of the sensor motion-induced noise is $-90dBVrms^2$ while the spectral power of the EM noise measured with a fixed sensor on the ground is $-105dBVrms^2$, and at the frequency of 100 Hz, the spectral power of the sensor motion-induced noise is $-70dBVrms^2$ while the spectral power of the EM noise measured with a fixed sensor on the ground is $-105dBVrms^2$. With applying Halverson stacking to an artificial noise transient generated by adding a noise-free transient to sensor motion-induced noise measured without pulsing, it is shown that the filtered transient is nearly consistent with the noise-free transient within a delay time of $0.5{{\mu}sec}$. The inversion obtained from this filtered transient is in accord with the true model with an error of 5%.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.548-555
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• 2000

The dynamic walking and the inverse dynamics of the biped walking robot is investigated in this paper. The biped robot is modeled with 14 degrees of freedom rigid bodies considering the walking pattern and kinematic construction of humanoid. The method of the computer aided multibody dynamics is applied to the dynamic analysis. The equations of motion of biped are initially represented as terms of the Cartesian coordinates, then they are converted to the minimum number of equations of motion in terms of the joint coordinates using the velocity transformation matrix. For the consideration of the relationships between the ground and foot, the holonomic constraints are added or deleted on the equations of motion. The number of these constraints can be changed by types of walking pattern with three modes. In order for the dynamic walking to be stabilizable, optimized trunk positions are iteratively determined by satisfying the system ZMP(Zero Moment Point) and ground conditions.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 가을 학술발표회 논문집
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• pp.241-248
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• 1999

Structural damage during an earthquake is caused by the response of the structure to the ground motion input at its base. The dynamic force produced in the structure are due to the inertia of its vibrating elements. The response of the structure exceeds the ground motion and this dynamic magnification depends on the duration and frequency content of the ground vibration, the soil properties at the site, distance from the epicenter and the dynamic characteristics of the structure. Earthquake load used in this study as a input data was artificially simulated with the design spectrum diagram in the Korean Earthquake Resistant Design Code. This paper presents the seismic analysis of the continuous preflex composite girder bridges according to variation of pier's height and span's length.

• Journal of Advanced Research in Ocean Engineering
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• 제1권2호
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• pp.134-147
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• 2015

This study proposes a method to determine the effective angular velocity of each motor of a specific four-rows tracked vehicle (FRTV) in order to follow a given turning radius. The configuration of the four-rows tracked vehicle is introduced, and its dynamics analysis model is built using the DAFUL commercial software. The soil has been assumed to be hard ground, and the friction force between the ground and the tracked links is calculated using the Coulomb friction model. This paper uses a simulation to show that the error in the position increased with respect to the angle of the curvatures, so a method is proposed to compensate for the error in the motion of the motors. Various simulations are then carried out to verify the proposed formulation. The effects of the soil characteristics and the driving velocity will be further investigated in future studies.