• 한국통신학회논문지
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• 제12권5호
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• pp.527-534
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• 1987

진동에 관한 비선형 1계연립미분방정식을 아나로그 시뮬레이션으로 2상전압제어발진을 시켜 유용성을 확인하였다. 2상신호를 각각 제곱하여 합성하는 부분과 곱셈부분의 실제회로 구성시 복잡하고 가격이 높아지므로 정류 회로와 스위칭회로로 대치하여 회로의 단순화와 가격 저렴화를 이루었다. 본 논문에서 제시된 회로는 제어 압력전압에 주파수가 정확한 비례관계를 가졌고, 응답 속도가 비교적 빠르고 또한 위상오차가 매우 적었으며 주파수비가 10:1 이상에서도 저왜율과 정진폭으로 동작하였다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1999년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.284-291
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• 1999

The reliability analysis is of great importance in their design since offshore towers are high-cost and high-risk structures. The design of platforms in the marine environment depends on results of the dynamic behavior of the structure during earthquakes and storm wave conditions. this paper presents results of an analytical study on evaluating dynamic response of steel jacket modelled by space frame elements. program $\boxDr$OFSPC$\boxUl$for the linear and nonlinear dynamic analysis of steel jacket platform has been developed using FORTRAN 90 programing language through the present study. Free vibration and dynamic behavior of steel jackets under regular and irregular wave and earthquake force are investigated using this program

• Wind and Structures
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• 제28권3호
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• pp.171-180
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• 2019

This paper presents a restart iterative approach for time-domain flutter analysis of long-span bridges using the commercial FE package ANSYS. This approach utilizes the recursive formats of impulse-response-function expressions for bridge's aeroelastic forces. Nonlinear dynamic equilibrium equations are iteratively solved by using the restart technique in ANSYS, which enable the equilibrium state of system to get back to last moment absolutely during iterations. The condition for the onset of flutter instability becomes that, at a certain wind velocity, the amplitude of vibration is invariant with time. A long-span suspension bridge was taken as a numerical example to verify the applicability and accuracy of the proposed method by comparing calculated results with wind tunnel tests. The proposed method enables the bridge designers and engineering practitioners to carry out time-domain flutter analysis of bridges in commercial FE package ANSYS.

• Smart Structures and Systems
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• 제23권4호
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• pp.337-345
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• 2019

This work resumes a research that proposes the use of the technique based on the dissipation energy of the shape memory alloy (SMA) ties. It focuses principally on the assessment of the effectiveness of the use of these smart materials on displacements, accelerations and the stresses of the minaret of the great mosque of Ajloun in Jordan. The 3-D finite element model of the minaret is performed by the ANSYS software. First of all, the proposed model is calibrated and validated according to the experimental results gathered from ambient vibration testing results. Then, a nonlinear transient analysis is considered, when the El-Centro earthquake is used as the input signal. Different simulating cases concerning the location, number and type of SMA devices are proposed in order to see their influence on the seismic response of the minaret. Hence, the results confirm the effectiveness of the proposed SMA device.

• 소음진동
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• 제7권1호
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• pp.33-41
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• 1997

경수로형 원자력발전소 표준화 작업의 일환으로 만들어진 한국표준형 원자력 발전소는 그 건설부지를 한반도뿐만 아니라 인접 아시아국가의 여러곳을 목표로 하고 있으며 이와 관련하여 안전정지지진의 레벨을 0.3g로 증가시키려는 시도가 계획되고 있다. 본 연구에서는 이와 같은 지진레벨 증가가 기존의 0.2g로 설계된 원자로 내부 구조물과 핵연료집합체에 미치는 영향을 평가하였다. 운전기준지진 및 안전정지지진의 응답을 비교함으로써 비선형 응답특성을 조사하였고 한국표준형 원자력발전소의 원자로 내부구조물 및 핵연료집합체의 설계 타당성에 대하여 언급하였다.

• Structural Engineering and Mechanics
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• 제67권1호
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• pp.9-20
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• 2018

In this paper, a framework is proposed for dynamic analysis of train-bridge systems with a damaged pier after barge collision. In simulating the barge-pier collision, the concrete pier is considered to be nonlinear-inelastic, and the barge-bow is modeled as elastic-plastic. The changes of dynamic properties and deformation of the damaged pier, and the additional unevenness of the track induced by the change of deck profile, are analyzed. The dynamic analysis model for train-bridge coupling system with a damaged pier is established. Based on the framework, an illustrative case study is carried out with a $5{\times}32m$ simply-supported PC box-girder bridge and the ICE3 high-speed train, to investigate the dynamic response of the bridge with a damaged pier after barge collision and its influence on the running safety of high-speed train. The results show that after collision by the barge, the vibration properties of the pier and the deck profile of bridge are changed, forming an additional unevenness of the track, by which the dynamic responses of the bridge and the car-body accelerations of the train are increased, and the running safety of high-speed train is affected.

• 한국공간구조학회논문집
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• 제18권4호
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• pp.97-104
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• 2018

A connected control method for the adjacent buildings has been studied to reduce dynamic responses. In these studies, seismic loads were generally used as an excitation. Recently, multi-hazards loads including earthquake and strong wind loads are employed to investigate control performance of various control systems. Accordingly, strong wind load as well as earthquake load was adopted to evaluate control performance of adaptive smart coupling control system against multi-hazard. To this end, an artificial seismic load in the region of strong seismicity and an artificial wind load in the region of strong winds were generated for control performance evaluation of the coupling control system. Artificial seismic and wind excitations were made by SIMQKE and Kaimal spectrum based on ASCE 7-10. As example buildings, two 20-story and 12-story adjacent buildings were used. An MR (magnetorheological) damper was used as an adaptive smart control device to connect adjacent two buildings. In oder to present nonlinear dynamic behavior of MR damper, Bouc-Wen model was employed in this study. After parametric studies on MR damper capacity, optimal command voltages for MR damper on each seismic and wind loads were investigated. Based on numerical analyses, it was shown that the adaptive smart coupling control system proposed in this study can provide very good control performance for Multi-hazards.

• Wind and Structures
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• 제38권2호
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• pp.119-128
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• 2024

The aerodynamic damping is an essential factor that can considerably affect the dynamic response of the cable-stayed bridge induced by crosswind load. However, developing an accurate and efficient aerodynamic damping model is crucial for evaluating the crosswind load-induced response on cable-stayed bridges. Therefore, this study proposes a new method for identifying aerodynamic damping of the bridge structures under crosswind load using an extended Kalman filter (EKF) and the particle filter (PF) algorithm. The EKF algorithm is introduced to capture the aerodynamic damping ratio. PF technique is used to select the optimal spectral representation of the noise. The effectiveness and accuracy of the proposed solution were investigated through full-scale vibration measurement data of the crosswind-induced on the bridge's girder. The results show that the proposed solution can generate an efficient and robust estimation. The errors between the target and extracted values are around 0.01mm and 0.003^o, respectively, for the vertical and torsional motion. The relationship between the amplitude and the aerodynamic damping ratio is linear for small reduced wind velocity and nonlinear with the increasing value of the reduced wind velocity. Finally, the results show the influence of the level of noise.

• 한국공간구조학회논문집
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• 제11권1호
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• pp.47-56
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• 2011

일반적으로 전단벽은 횡력저항 요소로서 널리 이용되고 있다. 대부분의 전단벽 구조물은 통로의 목적으로 개구부를 필요로 하게 되고 전단벽들 사이가 슬래브나 연결보로 연결된 병렬전단벽의 형태를 띠게 된다. 본 연구에서는 병렬전단벽 구조물의 연결보 중앙부에 LRB(Lead Rubber Bearing)를 도입하였고 이 시스템의 풍응답 저감성능을 검토하였다. 제안된 방법의 효과를 살펴보기 위하여 20층 및 30층 예제구조물을 구성하였고 인공풍하중을 작성하여 경계비선형 시간이력해석을 수행하였다. 제안된 방법이 풍하중을 받는 고층 병렬전단벽 구조물의 사용성 향상에 도움을 줄 수 있는지 평가하기 위하여 일본 진동성능평가기준을 적용하여 보았다. 해석결과 본 논문에서 제안하는 LRB를 사용하여 병렬전단벽을 연결하는 방식이 풍응답 제어성능 개선에 효과가 있는 것을 확인할 수 있었다.

• Earthquakes and Structures
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• 제1권4호
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• pp.327-344
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• 2010

This paper summarizes results of a comprehensive analytical study aimed at evaluating the influence of strong ground motion duration on residual displacement demands of single-degree-of-freedom (SDOF) and multi-degree-of-freedom (MDOF) systems. For that purpose, two sets of 20 earthquake ground motions representative of short-duration and long-duration records were considered in this investigation. While the influence of strong ground motion duration was evaluated through constant-strength residual displacement ratios, $C_r$, computed from the nonlinear response of elastoplastic SDOF systems, its effect on the amplitude and height-wise distribution of residual drift demands in MDOF systems was studied from the response of three one-bay two-dimensional generic frame models. In this investigation, an inelastic ground motion intensity measure was employed to scale each record, which allowed reducing the record-to-record variability in the estimation of residual drift demands. From the results obtained in this study, it was found that long strong-motion duration records might trigger larger median $C_r$ ratios for SDOF systems having short-to-medium period of vibration than short strong-motion duration records. However, taking into account the large record-to-record variability of $C_r$, it was found that strong motion duration might not be statistically significant for most of the combinations of period of vibration and levels of lateral strength considered in this study. In addition, strong motion duration does not have a significant influence on the amplitude of peak residual drift demands in MDOF systems, but records having long strong-motion duration tend to increase residual drift demands in the upper stories of long-period generic frames.