• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1998년도 지반조사위원회 봄 학술세미나
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• pp.37-46
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• 1998

Several researchers have developed a number of theoretical time factors to determine the coefficient of consolidation by biezocone excess pore water dissipation test in soft clay deposits. However, depending on the assumptions and analytical techniques, the estimated coefficient of consolidation could be in a considerably wide range even for a specific degree of consolidation. These solutions are obtained from an initial excess porewater pressure distribution which can be determined from. either the cavity expansion theory or the strain path method. The 야ssipation of the initial excess porelvater pressure has been usally simulated by means of linear-uncoupled consolidation analysis and then the dissipation curve is normalized by the initial excess porewater pressure for easy use. However. since there is no guidelines or rules on which method gives the best solution for obtaining the coefficient of consolidation from the dissipation curve, the final selection was only based on engineer's extrience and Judgements. Thus, such an arbitrary selection might be inappropriate for a specific site to characterize the consolidation behavior. In this paper, we reviewed various theoretical time factors and, based on this consideration, we mentioned needs for researches in selecting a specific solution that is compatible for Korean clays. Also we listed some source of errors that can be encountered in the procedure of dissipation analysis.

• 대한기계학회논문집
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• 제16권8호
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• pp.1429-1437
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• 1992

본 연구에서는 이완형 물성방정식을 바탕으로 하며 프와송 비가 일정하다는 가정을 하지 않는다. 또한 점탄성 지배방정식에 변분원리를 적용하고 유도되어진 식 에 유한요소해법을 사용하여 시스템 기본해석을 위한 연립방정식을 유도한다. 이와 함께 점탄성 물성함수의 유도 및 응력계산을 위한 공식화 과정도 설명한다. 제시된 방법론의 타당성 및 정확성을 보이기 위해서 평면응력 및 평면변형 문제의 변위 및 응력을 수치해석하여 이론해와 비교 검토하며, 아울러 시간증분의 변화와 Gauss poi- nts수가 수치정확도에 끼치는 영향을 조사한다.

• Steel and Composite Structures
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• 제35권3호
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• pp.405-413
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• 2020

Current study on the buckling analysis of steel plate in composite structures normally focuses on applying finite element method to derive the buckling stress. However, it is time consuming, computationally complicated and tedious for general use in design by civil engineers. Therefore, in this study an analytical study is conducted to predict the buckling behavior of steel plates in composite structures. Hand calculation method was proposed based on energy principle. Novel buckling shapes with biquadratic functions along both loaded and unloaded direction were proposed to satisfy the boundary condition. Explicit solutions for predicting the critical local buckling stress of steel plate is obtained based on the Rayleigh-Ritz approach. The obtained results are compared with both experimental and numerical data. Good agreement has been achieved. Furthermore, the influences of key factors such as aspect ratio, width to thickness ratio, and elastic restraint stiffness on the local buckling performance are comprehensively discussed.

• Structural Engineering and Mechanics
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• 제48권3호
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• pp.351-365
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• 2013

In this paper, unified nonlocal shear deformation theory is proposed to study bending, buckling and free vibration of nanobeams. This theory is based on the assumption that the in-plane and transverse displacements consist of bending and shear components in which the bending components do not contribute toward shear forces and, likewise, the shear components do not contribute toward bending moments. In addition, this present model is capable of capturing both small scale effect and transverse shear deformation effects of nanobeams, and does not require shear correction factors. The equations of motion are derived from Hamilton's principle. Analytical solutions for the deflection, buckling load, and natural frequency are presented for a simply supported nanobeam, and the obtained results are compared with those predicted by the nonlocal Timoshenko beam theory and Reddy beam theories.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권12호
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• pp.622-628
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• 2005

This paper is given a full detail of mathematical analyses of input current and output voltage for a novel active type power factor correction (PFC) converter. These are compared with harmonics components of input current for a conventional PFC converter. The proposed PFC converter is constructed in using a new loss-less snubber circuit to achieve a soft switching of control device. Also the proposed converter for discontinuous conduction mode (DCM) eliminates the complicated circuit control requirement and reduces the size of components. The input current waveform in the proposed converter is got to be a sinusoidal form of discontinuous pulse in proportion to magnitude of ac input voltage under the constant duty cycle switching. Therefore, input power factor is nearly unity and the control method is simple. Particularly, the stored energy of loss-less snubber capacitor is recovered with input side and increases input current from resonant operation. The result is that input power factor of the proposed converter is higher than that of conventional PFC converter. Some simulative results on computer and experimental results are included to confirm the validity of the analytical results.

• 정보처리학회논문지D
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• 제16D권3호
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• pp.295-306
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• 2009

질의실행시간최소화는 분산 데이타베이스 설계에 있어 가장 중요한 목적중의 하나이다. 총시간최소화는 온라인거래처리시스템의 목적인 반면, 반응시간최소화는 의사결정지원 질의시스템의 목적이다. 본 논문에서는 질의실행시간최소화를 달성하기 위해 질의를 세분화하여 최적의 데이터베이스 사이트에 할당하는 분석모델을 개발하였으며, 문제해결방법으로 유전자알고리즘을 채택하였다. 총시간최소화 관점에서의 질의실행 계획은 반응시간최소화 관점의 질의실행계획에는 적합하지 않다는 것을 증명하였으며, 그 반대의 경우도 증명하였다. 최대 20개의 조인이 포함되는 질의를 설계하여 시뮬레이션 실험을 통해 테스트를 수행하였고, 유전자알고리즘과 완전한 전수조사와의 결과를 비교함으로써 모든 경우에 유전자알고리즘을 채택한 해결책이 최적의 결과를 도출하였음을 증명하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1054-1056
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• 2003

The slotless Permanent-Magnet Linear Synchronous Motors (PMLSM) have been developed for factory automation, transportation applications, wafer steppers, conveyance system, and so on. The current analysis and design are treated in air-cored PMLSM. This paper presents a design and analysis solutions for the general class of iron-cored Permanent magnet Linear Synchronous motor (PMLSM). In our design and analysis, rotor consisting of permanent magnets and slot less iron-cored coil stator are treated in a uniform way via vector potiential. For one such motor structure we give analytical formulas for its magnetic field, opitimal permanent magnet and winding coil thickness, trust force. We also provide comparisons of three types in Halbach, vertical, and horizontal magnet array.

• 한국자동차공학회논문집
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• 제6권6호
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• pp.24-30
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• 1998

A directly coupled Boundary Element and Finite Element Model was applied to the dynamic analysis of a coupled acoustic silencer with vibratory wall. In this cupled BEM-FEM muffler model, the BEM model was used to discretize the acoustic cavity and the FEM model was used to discretize the vibratory wall structure. Then the BEM model was coupled with the FEM model. The results of the coupled BEM-FEM model for the dynamic analysis of the simple expansion type reactive muffler configurations with flexible walls were verified by comparing the predicted results to analytical solutions. In order to investigate the effects of the muffler's structural flexibility on its transmission loss(TL) characteristics, the results of the coupled BEM-FEM model in conjunction with the four-pole parameter theory were utilized. The muffler's TL characteristics using the BEM-FEM coupled model with flexible walls as compared to other muffler configurations was studied. Finally the muffler's TL values with respect to different wall's thickness are predicted and compared.

• 한국산학기술학회논문지
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• 제12권12호
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• pp.5984-5989
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• 2011

양단 핀지지 기둥부재의 중간 위치에 수평재를 연결하고 설치된 수평재의 양끝단과 기둥의 상하끝단을 트러스로 연결된 트러스보강 단일기둥시스템은 보강되지 않은 경우에 비해 그 좌굴강도가 상당수준 향상될 수 있다. 수평재가 설치된 기둥중간지점에서의 수평 및 회전 자유도에 대한 제한하여 기둥의 유효좌굴길이를 줄이는 효과를 통해 강도향상이 구현된다. 본 연구에서는 해석적 해와 탄성 및 비탄성 유한요소해석을 통해 보강된 평면내 단일기둥 시스템의 좌굴강도를 정량적으로 산정하였고 그 결과를 비교하였다. 예제해석을 통해 보강된 단일기둥시스템은 보강되지 않은 단순기둥에 비해 최대 8배까지 좌굴강도가 향상될 수 있음이 확인되었다.

• 한국안전학회지
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• 제11권4호
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• pp.3-9
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• 1996

In this study, comparison of theoretical solutions with experimental results is examined through fracture conditions for the case of float glasses subjected static loading. The range of fracture generation limits and critical penetration energies are solved according to the impactor mass under the high velocity, and analytical method of fracture strength and penetration strength are presented. Also, fracture patterns are investigated according to impact velocities. The results obtained from this study are as follows ; 1) Radial cracks are generated from the loading point regardless of plate thickness in the case of the plate subjected to the static loading. In the case of high-speed impact, dimensions of ring cracks become to smaller and length of radial cracks becomes shorter with the rapidity of impact velocity. 2) Kinetic change volume of collision after/before is constant regardless of velocities over the range of critical penetration velocity. 3) Although the same impact energy is working, the critical penetration energy is increased with the shorter of impactor mass. 4) Although the same impact energy is working, the penetration fracture of lighter Impactor mass is generated more than that of heavier impactor mass, and the impulse of lighter impacter mass appear more than that of heavier impactor mass. Therefore, the penetration fracture in the case of greater impulse is generated earlier regardless of the of the dimensions of Impact loading.