• 한국터널지하공간학회 논문집
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• 제3권4호
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• pp.3-15
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• 2001

일반적으로 지진발생시 터널구조물은 지상구조물에 비해 입는 피해가 매우 작다고 해서 내진설계에 대한 인식이 부족하였다. 그러나, 현재까지 많은 유형의 지하터널이 건설되었고, 앞으로는 더 많은 건설계획이 있으므로 지진시 지하터널구조물에 대한 안정성 확보가 중요하고 많은 연구가 필요하다. 본 논문에서는 지진발생시 터널의 동적거동을 파악하고, 적절한 내진해석을 제안하기 위해서 응답변위법과 동적해석법을 이용하여 내진해석을 실시하였다. 해석 결과는 지진발생시 터널구조물이 지반의 변형에 순응한다는 것을 나타내었고, 응답변위법에 의한 내진해석이 동적해석법에 의한 것보다 대부분의 경우 더 보수적인 해석이라는 것을 보여주었으며, 마지막으로 동적해석시 간편화된 2차원유한요소해석이 복잡한 3차원해석보다 내진해석시 더 효율적이라는 것을 보여주었다. 갱구부의 내진해석결과에서는 지진파가 터널축과 평행하게 진행할 때 갱구부에 설치된 라이닝에 가장 큰 단면력이 발생하는 것으로 나타났다.

• Journal of Electrical Engineering and Technology
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• 제7권4호
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• pp.564-569
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• 2012

This paper proposes a hybrid-excited linear synchronous motor (LSM) that has potential applications in a magnetically levitated vehicle. The levitation and thrust force characteristics of the LSM are investigated by means of three-dimensional (3-D) numerical electromagnetic FEM calculations and experimental verification. Compared to a conventional LSM with electromagnets, a hybrid-excited LSM can improve levitation force/weight ratios, and reduce the power consumption of the vehicle. Because the two-dimensional (2-D) FE analysis model describes only the center section of the physical device, it cannot express the complex behavior of leakage flux, which this study is able to predicts along with levitation and thrust force characteristics by 3-D FEM calculations. A static force tester for a hybrid-excited LSM has been manufactured and tested in order to verify these predictions. The experimental results confirm the validity of the 3-D FEM calculation scheme for the description of a hybrid-excited LSM.

• 콘크리트학회논문집
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• 제26권1호
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• pp.57-62
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• 2014

이 연구에서는 수직으로 긴 매스 구조물에 적합한 파이프쿨링 공법을 제안하기 위하여 기존의 파이프쿨링 공법과는 달리 파이프를 수직으로 설치하는 연직파이프쿨링 공법을 개발하였다. 타당성을 검토하기 위하여 해석대상 부재의 형상($1{\times}3{\times}20m$, $4{\times}4{\times}4m$)을 대상으로 하여 FEM 해석을 수행하였으며, 온도 및 응력 변화와 온도균열 지수 등을 검토하였다. 그 결과, 매스콘크리트 구조물의 온도균열 제어에 효과가 있는 것을 확인할 수 있었다.

• 전기학회논문지
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• 제57권12호
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• pp.2194-2198
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• 2008

In this paper, the construction of secondary reaction plate is analyzed by 3-D Finite Element Method(3-D FEM) to consider the influence of its variation on the transverse edge effect of LIM. The effective 3-D analysis model for considering the transverse edge effect caused by the finite widths of the primary and the secondary is proposed. The simple method measuring the transverse edge effect by using the patterns of currents induced in the secondary reaction plate is also proposed. With this effective analysis method, various models of secondary reaction plate with overhang and cap has been analyzed to consider the relationship between the construction of secondary reaction plate and the transverse edge effect of LIM.

• 한국지반공학회지:지반
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• 제12권4호
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• pp.5-20
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• 1996

본 논문은 비선형 유한요소 프로그램을 이용하여 강관보강형 다단그라우팅의 지반보강효과와 주변지반의 거동을 검토하기 위하여 지반조건이 터널천단부에 충적층이 분포하여 강관다단그라우팅을 적용한 현장을 대상으로 유한요소 2차원과 3차원 모델로 나누어 해석하였다. 해석 결과 강관보강효과를 분석하기 위해서는 2차원해석보다는 3차원해석이 필수적 임을 알 수 있었으며, 그 효과는 막장부근의 음력집중현상을 골고루 분포시켜주는 강관의 강성에 의하여 안전율이 상대적으로 높아짐을 확인할 수 있었다. 한편 터널천단의 침하량 변화는 터널막장위치가 측정지점에 도달하기 이전에 총예상변위의 40%정도가 발생되며, 막장위치가 측정지점을 통과하여 터널직경정도의 거리에 도달하는 동안 전체예상변위의 60%가 발생될 수 있는 것으로 나타났다. 또한 강관보강으로 인하여 주변지반의 변위 및 응력의 억제범위는 터널 천단부 즉 깊이비 0.83 에서 0.38범위와 터널막장전방 26(d:터널직경)지점까지 나타나며, 변위억제효과는 총 예상변위량의 약 200정도임을 알 수 있었다.

• Geomechanics and Engineering
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• 제28권3호
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• pp.225-237
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• 2022

Settlement evaluation is important for shallow tunnels in big cities to estimate the settlement that occurs due to the excavation of twin tunnels. The majority of earlier research on analytical solutions, on the other hand, concentrated on calculating the settlement for a single tunnel. This research introduces a procedure to evaluate the settlement induced by the excavation of twin tunnels (two parallel tunnels). In this study, a series of numerical analysis were performed to validate the analytical solution results. Two geological conditions were considered to derive the settlement depending on each case. The analytical and numerical methods were compared, which involved considering many sections and conducting a parametric study; the results have good agreement. Moreover, a comparison of the 3D flat model and 2D (FEM) with the analytical solution shows that in the fill soil, the maximum settlement values were obtained by the analytical solution. In contrast, the values obtained by the analytical solution in the rock is more conservative than those in the fill. Finally, this method was shown to be appropriate for twin tunnels dug side by side by utilizing finite element analysis 3D and 2D (PLAXIS 3D and PLAXIS 2D) to verify the analytical equations. Eventually, it will be possible to use this approach to predict settlement troughs over twin tunnels.

• Journal of international Conference on Electrical Machines and Systems
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• 제2권4호
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• pp.399-404
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• 2013

The rotor overhang is used to enhance air-gap flux and improve power density. Due to asymmetry in the axial direction caused by the overhang, the time consuming 3D analysis is necessary to design the motor with overhang. To solve this problem, this paper proposes the equivalent magnetic circuit model (EMCM) that can consider overhang effects without the 3D analysis by using effective air-gap length. The analysis time can be reduced significantly via the proposed EMCM. The reduction of the analysis time is essential for the preliminary design of the motor. In order to verify the proposed model, the 3-D finite-element method (FEM) analysis is adopted. 3-D FEM results confirm the validity of the proposed EMCM.

• 대한기계학회논문집
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• 제18권8호
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• pp.2113-2122
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• 1994

The 3-D FEM analysis for simulating the stamping operation of planar anisotropic sheet metals with arbitrarily-shaped tools is introduced. An implicit, incremental, updated Lagrangian formulation with a rigid-viscoplastic constitutive equation is employed. Contact and friction are considered through the mesh-normal, which compatibly describes arbitrary tool surfaces and FEM meshes without depending on the explicit spatial derivatives of tool surfaces. The consistent full set of governing relations, comprising equilibrium equation and mesh-normal geometric constraints, is appropriately linearized. The linear triangular elements are used for depicting the formed sheet, based on membrane approximation. Barlat's non-quadratic anisotropic yield criterion(strain-rate potential) is employed, whose in-plane anisotropic properties are taken into account with anisotropic coefficients and non-quadratic function parameter. The planar anisotropic finite element formulation is tested with the numerical simulations of the stamping of an automotive hood inner panel and the drawing of a hemispherical punch. The in-plane anisotropic effects on the formability of both mild steel and aluminum alloy sheet metals are examined.

• 대한건축학회논문집:구조계
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• 제35권9호
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• pp.159-169
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• 2019

This work presents the three-dimensional extended strain smoothing approach in the framework of finite element method, so-called smoothed finite element method (S-FEM) for quasi-incompressible hyperelastic materials undergoing the large deformations. The proposed method is known that the incompressible limits, such as over-estimation of stiffness and distorted mesh sensitivity, can be overcome in two dimensions. Therefore, in this paper, the idea of Cell-based, Edge-based and Node-based strain smoothing approaches is extended to three-dimensions. The construction of subcells and smoothing domains for each methods are explained. The smoothed strain-displacement matrix and the stiffness matrix are obtained on each smoothing domain in the same manner with two-dimensional S-FEM. Various numerical tests are studied to demonstrate the validity and accuracy of 3D-S-FEM. The obtained results are compared with analytical solutions to express the efficacy of the methods.

• 한국산학기술학회논문지
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• 제15권11호
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• pp.6458-6463
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• 2014

본 논문의 목적은 38인승 승강기 제동장치의 설계 및 유한요소해석이다. 최근 승강기의 안전성이 부각되면서 비상 제동장치의 필요성이 높아졌으며 이에 따라 새로 개발된 제동장치의 안전성을 확인하기 위하여 Solid Works를 활용하여 모델링 하였으며 유한요소해석 코드인 ANSYS를 활용하여 유한요소해석을 수행하였다. 해석결과로서 총변형량, 응력, 변형률을 구하였다.