• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.10a
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• pp.53-56
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• 2000

This paper discusses the horizontally rotaling wind power generator. Quasi static analysis are applied to performance. Translational velocity. which varies on the distance from the rotating wind power generator is effective in speed. In high rotation. the reverse torque reduces the total effective troque. It is recommended to giver efforts to redutorque for the acceptavle performance of the horizontallv rogatting tvpe generator.

• Journal of Korean Society of Steel Construction
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• v.13 no.2
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• pp.163-176
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• 2001

In this paper, the stress resultants and displacements of simply supported curved girder based on the flexural torsional theory considering torsional warping effects are analyzed. And elastic equations of continuous curved girder are obtained by using energy method. Also, bending moment warping torsional moment diagram, pure torsional moment diagram, shearing force diagram, and deflection diagram of continuos curved girder bridge subjecting to vertical loads and uniform loads are presented.

• Computational Structural Engineering
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• v.9 no.1
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• pp.101-113
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• 1996

In this paper, the finite element formulation for the thermal analysis of quasi-static, uncoupled, homogeneous, isotropic and linear viscoelastic problems is presented based on the principle of virtual work. The viscoelastic material is assumed to be thermorheologically simple, which is well known material property in a large class of high polymers. The variational formulation and the finite element equation in matrix from are derived. Effective generation and storage of the hereditary stiffness matrices are given in detail especially for the case of the steady state temperature distribution T=T(x). Some numerical examples are given and compared with published results to show the versatility of the derived finite element formulations.

• Journal of the Korean Geotechnical Society
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• v.17 no.5
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• pp.197-207
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• 2001

1980년대 이래 국내 터널의 시공법은 원지반의 강성을 활용한 NATM이 주를 이루고 있다. 그러나 NATM은 터널내부에 설치되는 내부라이닝의 여러 가지 문제점을 내포하고 있기 때문에 노르웨이에서는 조립식 터널 라이닝(Pre-Cast Concrete Lining, PCL)을 개발하여 현장타설 콘크리트 라이닝의 문제점을 해결하고자 하였다. 그러나 노르웨이와 같은 북유럽지역에서는 지진이 거의 발생되지 않고 있기 때문에 PCL공법 개발당시에 지진에 대한 영향을 고려하지 못하였다. 따라서 PCL공법을 국내에 도입하기 위해서는 먼저 지진에 대한 영향을 분석하여야 할 것으로 판단되므로 본 연구에서는 PCL공법 적용시 지진에 대한 안정성 평가 및 합리적 내진해석을 위한 연구를 수행하고자 하였다. PCL의 내진성능을 판단하기 위하여 먼저 국내에서 주로 많이 사용되고 있는 해석기법인 유사정적해석법과 응답스펙트럼해석법을 이용하여 분석하였으며 지반과 구조물의 상호작용에 대한 영향을 분석하기 위해 시간이력해석을 수행하여 터널심도별 PCL의 내진성능을 분석하였다. 이와 같은 방법으로 PCL의 내진해석을 수행한 결과, 부재에 발생된 응력이 허용응력 이내에서 발생되어 PCL의 내진성능을 확보된 것으로 판단된다. 또한 시간이력해석에 의한 지반-구조물 해석을 수행한 결과에 의하면 PCL의 내진성능을 확보하기 위한 터널의 최소 토피고가 터널직경에 2배 이상인 것으로 확인되었다. 또한 단순 구조물의 내진해석만으로는 PCL의 내진성능을 과소평가할 우려가 있는 것으로 나타났다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.40-47
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• 2021

In this study, the structural behavior by the details of the lap region with the headed bar was estimated through finite element analysis. To solve the finite element analysis of the anchorage region with complex contact conditions and nonlinear behavior, a quasi-static analysis technique by explicit dynamic analysis was performed. The accuracy of the finite element model was verified by comparing the experimental results with the finite element analysis results. It was confirmed that the quasi-static analysis technique well reflected the behavior of enlarged headed bar connection. As a result of performing numerical analysis using 21 finite element models with various development lengths and transverse reinforcement indexes, it was confirmed that the increase of development length and transverse reinforcement index improved the maximum strength and ductility. However, to satisfy the structural performance, it should be confirmed that both design variables(development length and transverse reinforcement index) must be enough at the design criteria. In the recently revised design standard(KDS 14 20 52 :2021), a design formula of headed bar that considers both the development length and the transverse reinforcing bar index is presented. Also the results of this study confirmed that not only the development length but also transverse reinforcing bars have a very important effect.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.4
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• pp.555-567
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• 2013

A finite element formulation for a Rayleigh-damped Bernoulli-Euler beam subjected to support motions, which accompanies quasi-static rigid-body motion, is presented by using the quasi-static decomposition method. Moving support beam elements, one of whose nodes is coincident with the moving support, are developed to represent the effect of a moving support. Statically determinate beams subjected to support motions can be modeled successfully by using moving support elements. Examples of cantilever and simply-supported beams subjected to support motions are illustrated, and the numerical results are compared with the analytical solutions. The comparison shows good agreement.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.1
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• pp.141-149
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• 2009

In this paper, quasi-static FDTD method is implemented by FORTRAN programming, and it is used for analysis of body induced current in middle frequencies. The quasi-static FDTD program is validated by comparing the calculation result with analytic solution of the test model, to which it is difficult to apply conventional FDTD. It is confirmed that the time-step is reduced by $5.68{\times}10^6$ times. Using validated numerical technique, body induced current distribution in high resolution 3-D human model is calculated for 20[kHz] magnetic field exposure and 1[MHz] electric field exposure. Also, the effect of grounding condition of both feet on the distribution and amplitude of the induced current is analyzed. It is expected that this research can be applied to various fields including safety assessment of body induced current and development of diagnosis devices using bio-electricity.

• Journal of the Korea Concrete Institute
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• v.28 no.1
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• pp.75-84
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• 2016

The purpose of this study was to investigate the performance of solid reinforced concrete columns with triangular reinforcement details. The proposed reinforcement details has economic feasibility and rationality and makes construction periods shorter. A model of solid reinforced concrete columns with triangular reinforcement details was tested under a constant axial load and a quasi-static, cyclically reversed horizontal load. A computer program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. The used numerical method gives a realistic prediction of performance throughout the loading cycles for several test specimens investigated. As a result, proposed triangular reinforcement details for material quantity reduction was superior to existing reinforcement details in terms of required performance.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.10
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• pp.1003-1009
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• 2012

An instantaneous environmental noise simulation method emitted by a moving high-speed train by quasi-stationary analysis is proposed in this study. In the method, the propagation attenuations from stationary point sources on segmented railways to a receiver are calculated using a general purpose environmental noise prediction program ENPro based on the ISO 9613-2 method. Then, the instantaneous environmental noise at a receiver due to a moving high-speed train considering convection effect is evaluated with the information on the propagation attenuations from the instantaneous train location to the receiver and the sound power levels and directivity of stationary point sources evaluated by German Schall 03 (2006). To demonstrate the validity of proposed method, simulated and measured time history of instantaneous noise for KTX-I and KTX-II on running are compared and the results show that the method can be utilized for the train noise source identification as well as the simulation of instantaneous environmental noise emitted by a high-speed train.

• Journal of the Korean Society for Railway
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• v.15 no.6
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• pp.588-596
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• 2012

This paper presents a new semi-analytical annular Mindlin plate element with which out-of-plane natural vibration of thick disks can be analyzed simply, efficiently, and accurately through FEM by including effects of rotary inertia and transverse shear deformation. Using static deformation modes which are exact solutions of equilibrium equations of annular Mindlin plate, the element interpolation functions, stiffness and mass matrices corresponding to each number of nodal diameters are derived. The element is capable of representing out-of-plane rigid-body motions exactly and free from shear locking. Natural frequencies of uniform and multi-step disks with or without concentric ring support are analyzed by applying the presented element. Such results are compared with theoretical predictions of previous works or FEA results obtained by using two-dimensional shell element to investigate the convergence and accuracy of the presented element.