• Journal of the Society of Naval Architects of Korea
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• v.30 no.4
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• pp.153-168
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• 1993

The ship sailing among waves suffers from the various wave loads that comes from its motion throughout its life. In the rationally-based design, the dynamic structural analysis is carried out using dynamic wave loads provided from the results of the ship motion calculation as the rigid body. This method is based on the linear theory assumed low wave height and small amplitude of motion. But at the rough sea condition, relatively high wave compared to the height ship's depth is induced the large ship motion, so configuration of the ship section below waterline changes rapidly at each time. This re-sults in a non-linear problem. Considering above situation we have already introduced the non-linear dynamic strength analysis method for the hull girder(refer vol. 29. No.4 November, 1992, Journal of SNAK). In this paper, estimation of the hull girder strength for various ship types such as tankers, containers and log carriers is carried out based on the introduced non-linear method. We expect that the results will be used as useful basic data for the es-timation of dynamic strength of ships in the rough sea.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1991.04a
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• pp.119-125
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• 1991

본 연구에서는 일반적인 6자유도의 비대칭 강체가 3방향 탄성계수를 갖는 마운트에 지지되어 있는 6장도계의 진동해석기법을 확립하고, 고유진동, 강 제진동응답 및 진동전달력해석을 위한 프로그램을 개발하였다. 아울러 실제 응용된 사례와 타종의 마운트를 적용한 결과를 비교함으로써 설계의 타당성 을 검증하였다.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06d
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• pp.13-17
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• 1998

집속음장이 고조파성분을 이용한 초음파영상의 특성을 해석하는 초기단계로서 음축에 수직하게 놓인 강체판의 직선 edge가 집속 가우스빔을 회절시킨다고 가정하고, edge의 전후에서 발생하는 제 2고조파를 고려해서 회절음장을 해석하였다. 계산에서는 그린함수의 간단화를 위해 , Fresnel 근사를 이용하였고 실험에서는 성형전극을 형성시킨 요면 압전진동자에 의한 1.9MHz 집속가우스음원에 의해 만들어지는 초음파 빔에 수직하게 edge을 삽입시켰다. 회절 edge 후방에서 음장을 관측한 결과, 제 2고조파의 빔형상을 제외하고는 계산치와 실험치가 잘 일치하고 있다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.1
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• pp.9-17
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• 2013

In this study, an efficient analytical model for the dynamic analysis of tall buildings with a shear wall-frame structural system has been proposed. A shear wall-frame structural system usually consists of a core wall showing flexural behavior and a frame presenting shear behavior. Therefore, the deformed shape of the shear wall-frame structural system is shown by the combination of flexural mode and shear mode. These characteristics should be considered when an efficient analytical model is developed. To this end, the effect of shear wall and frame on the dynamic behavior of a tall building with a dual system has been separately investigated. In this study, the structural characteristics of a separated individual shear wall model and the frame model without shear wall has been evaluated. In order to consider the effect of the shear wall in the frame model without shear wall, a rigid body was used instead of the shear wall. Each equivalent model for the separated shear wall part and frame part has been independently developed and two equivalent models were then combined to create an efficient analytical model for tall buildings with a shear wall-frame structural system. In order to verify the efficiency and accuracy of the proposed method, time history analyses of tall buildings with a shear wall-frame system were performed. Based on analytical results, it has been confirmed that the proposed method can provide accurate results, requiring significantly reduced computational time and memory.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.10
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• pp.833-844
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• 2018

This paper aims to predict the aerodynamic characteristics of individual rotor for the gust and flight conditions. Transformation procedure into the wind frame is conducted to analyze the gust. Hover, forward, and climb flight conditions of an individual rotor are analyzed using the blade element momentum theory (BEMT) considering the rigid blade flapping motion. XFOIL is used to derive aerodynamic results. Validation for hover, forward flight, and climb conditions are conducted using the present BEMT. In addition, a static experimental environment is constructed. The experimental results and the present BEMT are compared and verified.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.6
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• pp.771-780
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• 2010

This paper describes the design process of a six-component force/torque (F/T) sensor. The new six-component F/T sensor having leaf spring ends has been developed using a cross beam structure as the basic sensing element. Fundamental strain analysis of both ends fixed beam having a leaf spring structure is performed by finite element analysis. In order to obtain similar output sensing strains from the six component loads and minimize coupling strains, the optimal location of strain gages is determined and the strain gages are connected so that the bridge circuits with four strain gages would be balanced. Using leaf spring ends instead of rigid fixed ends, remarkable increment in output sensing strain can be achieved for two component forces. Several modifications in design result in a similar sensing strain of approximately $400\;{\mu}m/m$ for the six-component forces and moments, and a reduced coupling strain of $0\;{\mu}m/m$ between the forces and moments.

• Journal of the Korean Geotechnical Society
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• v.23 no.4
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• pp.79-90
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• 2007

Behaviors of instrumented steel sheet piles which are installed in sand ground by vibratory hammer were investigated. Especially, stresses acting on the pile during vibratory driving, efficiency factor which reflects differences between theoretical driving force and actually delivered acting force, justifiability of rigidity of steel sheet pile, dynamic resistance characteristics of soil and penetration characteristics of sheet pile were analysed. According to the field test results it is justifiable that steel sheet pile behaves as a rigid body during vibratory driving. And it can be seen that maximum stress acting on sheet pile section is far less than tensile strength of the material. Value of the maximum section force at sheet pile head was 72% of that estimated from theoretical equation. Magnitudes of displacement amplitudes computed from displacement-time history curve corresponding to four penetration depths were in the range of 16 $\sim$ 75% of that specified by manufacturer.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.516-520
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• 2011

본 논문에서는 먼저 흥인지문에 대해 상시진동실험을 수행하고, 그 데이터를 분석하여 흥인지문의 고유진동수, 모드, 감쇠비의 특성을 분석하였다. 그 결과로부터 흥인지문의 병진모드를 파악하였고, 병진모드에서 측정한 여러 기둥의 모드 상대크기와 위상이 동일함을 확인하였다. 저차 병진모드에서 모든 기둥이 같은 방향으로 강성을 발휘하기 때문에 각층의 강성을 합한 등가의 층강성을 가지는 2자유도의 동적강체해석모델을 제시하였다. 이 해석모델은 선형 범위 내에서 거동한다는 것으로 가정하여 층강성을 산정하였다. 실제 흥인지문의 접합부에는 부재간의 이음과 맞춤에 의한 마찰력이 작용한다. 접합부를 누르는 무거운 지붕하중에 의해 이 마찰력은 증가하게 되고, 이로써 횡하중에 저항하게 된다. 이러한 접합부에 강한 횡하중이 작용하게 되면, 접합부의 이완 및 마찰력의 저하 등으로 인하여 횡강성의 저하가 급격히 일어나는 비선형 특성을 갖게 된다. 이러한 흥인지문의 비선형적인 특성을 파악하기 위해 흥인지문 해석모델에 쿨롱 마찰력을 도입하여 비선형적인 해석모델을 제시하였다.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.439-442
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• 2002

구형 배플을 가진 피스톤 음원에 대한 방사임피던스 특성을 유한요소법과 하이브리드형 무한요소법을 사용하여 수치해석하였다. 강체 구형 배플에 있어서 피스톤 음원의 방사면 크기에 따른 자기방사임피던스 변화와 피스톤 음원간의 상호방사임피던스 변화를 고찰하였다. 방사면의 크기에 따라 자기방사임피던스 변화 및 음원간의 상호방사임피던스 변화를 검토한 결과 알려진 해석해와 일치하였다. 또한, 비강체 구형 배플의 특성 임피던스 변화에 따른 자기방사임피던스 및 음원간의 상호방사임피던스 특성 변화를 고찰하였다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.3
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• pp.520-525
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• 2016

In this paper, Characteristic of power conversion unit of a railway vehicles according to contact loss in feeding system that applied impedance of rigid conductor is analyzed. It applied impedance of rigid bar in modeling of electric railway system. Railway vehicles are performed of modeling based on the performance of the electric railway vehicle. Effects of the contact loss in the power conversion unit were analyzed via main transformer of railway vehicle, the input and output voltage characteristics of the converter through contact loss was generated after linking the vehicle with feeding system.