• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.197-202
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• 2004

In order to design accurately sand compaction pile (SCP) method with low replacement area ratio, it is important to understand the mechanical interaction between sand piles and clays and its mechanism during consolidation process of the composition ground. In this paper, a series of numerical analyses on composition ground improved by SCP with low replacement area ratio were carried out, in order to investigate the mechanical interaction between sand piles and clays. The applicability of numerical analyses, in which an elasto-viscoplastic consolidation finite element method was applied, could be confirmed comparing with results of a series of model tests on consolidation behaviors of composition ground improved by SCP. And, through the results of the numerical analyses, each mechanical behaviors of sand piles and clays in the composition ground during consolidation was elucidated, together with stress sharing mechanism between sand piles and clays.

• 대한기계학회논문집A
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• 제27권9호
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• pp.1597-1606
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• 2003

Static analysis using hybrid finite element(FE) method has been applied to characterize the influence of position, runout and thickness errors of the sun, ring and planet on the bearing forces and critical tooth stress. Some guidelines for tolerance control to manage critical stress and bearing forces are deduced from the results. Carrier indexing error planet assembly and planet tooth thickness error are most critical to reduce planet bearing force and maximize load sharing as well as to reduce critical stresses. Sun and carrier bearing forces due to errors increase several times more than those of normal condition.

• 소성∙가공
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• 제31권4호
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• pp.200-206
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• 2022

The finite element analysis is one of the representative methods for predicting the materials behavior for experiments that are difficult to perform empirically. Constitutive equations are essential for reducing computation time and sharing data because they enable finite element analysis simulations through simple formulae. However, it is difficult to derive accurate flow curves for all materials as most constitutive equations are not formulated based on their physical meaning. Also, even if the constitutive equation is a good representation of the flow curve to the experimental results, some fundamental issues remain unresolved, such as the effect of mesh size on the calculation results. In this study, a new constitutive equation was proposed to predict various materials by modifying the combined Swift-Voce model, and the calculation results with various mesh sizes were compared to better simulate the experimental results.

• Journal of Mechanical Science and Technology
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• 제18권4호
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• pp.606-621
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• 2004

A dynamic analysis using a hybrid finite element method was performed to characterize the effects of a number of manufacturing errors on bearing forces and critical tooth stress in the elements of a planetary gear system. Some tolerance control guidelines for managing bearing forces and critical stress are deduced from the results. The carrier indexing error for the planet assembly and planet runout error are the most critical factors in reducing the planet bearing force and maximizing load sharing, as well as in reducing the critical stress.

• Korean Journal of Mathematics
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• 제20권4호
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• pp.463-475
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• 2012

Cooperation is an essential element in mathematics education with independence. We observe cooperative learning and apply it to the education spot. We conducted cooperative learning experiment with students who were not ready for the prerequisite learning of college mathematics. We try to make up the prerequisite learning through collaborative learning to them. We discuss how cooperative learning affects the students who were not ready for the prerequisite learning of college mathematics.

• 한국CDE학회논문집
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• 제11권5호
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• pp.384-392
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• 2006

In this research, the feasibility of distributed finite element analysis system with STEP and CORBA has been investigated. The enabling technologies such as CORBA and Java play key roles in the development of integrated and geographically distributed application software. In addition to the distribution of analysis modules, numerical solution process itself is again divided into parallel processes using multi-frontal method for computational efficiency. In contrast to the specially designed parallel process for specific hardware, CORBA-based parallel process is well suited for heterogeneous platforms over the network. The idea of Web-based distributed analysis system may be applied to the engineering ASP for design and analysis in the product development processes. We believe that the proposed approach for the analysis can be extended to the entire product development process for sharing and utilizing common product data in the distributed engineering environment, thus eventually provide basis for virtual enterprise.

• 한국지반공학회논문집
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• 제15권1호
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• pp.79-98
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• 1999

본 연구에서는, 강관스커트 보강 조립토 군말뚝에 초점을 두고, 상부 매트기초와 하부기초지반 사이의 접촉면 각 지점별 불균등 침하량 예측을 위한 간편 유한요소해석기법과 이에 근거한 각 말뚝 인접지반의 하중분담비 평가방법 및 극한지지력 평가절차 등을 제시하였다. 또한 제시하고자 하는 기법의 적합성과, 이를 토대로 한 극한지지력 예측결과의 타당성을 확인하기 위해, $PENTAGON_{3D$ 유한요소 프로그램을 이용한 해석결과와의 비교.분석이 수행되었다. 이외에도, 강관스커트 보강유형에 따른 거동특성 분석과 스커트 보강에 의한 극한지지력 증대효과를 관련 설계변수와 연계한 분석 등을 수행하였다.

• 한국지반환경공학회 논문집
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• 제13권6호
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• pp.67-72
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• 2012

본 연구에서는 사질지반에서 말뚝전면기초와 전면기초와의 거동을 유한요소해석을 이용하여 비교하였다. 25개의 시추공의 표준관입시험의 결과를 이용하여 구한 토질정수를 유한요소해석에 사용하였다. 말뚝을 사용하지 않은 전면기초의 경우 $8m{\times}8m$ and $15m{\times}15m$의 크기의 정규화된 침하계수는 각각 1.02~1.15 and 0.64~0.81의 범위로 나타났다. 전면기초의 두께는 부등침하와 휨모멘트에 영향을 미치고 하중분담과 최대침하에는 큰 영향이 없었다. 말뚝의 간격은 최대침하와 부등침하, 휨모멘트에, 말뚝의 하중분담에 영향을 받고 반면에 부등침하와 휨모멘트는 말뚝의 길이에는 큰 영향을 미치지 않는 것으로 나타났다.

• Wind and Structures
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• 제28권3호
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• pp.181-190
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• 2019

Light-frame wood structures have the ability to carry gravity loads. However, their performance during severe wind storms has indicated weakness with respect to resisting uplift wind loads exerted on the roofs of residential houses. A common failure mode observed during almost all main hurricane events initiates at the roof-to-wall connections (RTWCs). The toe-nail connections typically used at these locations are weak with regard to resisting uplift loading. This issue has been investigated at the Insurance Research Lab for Better Homes, where full-scale testing was conducted of a house under appropriate simulated uplift wind loads. This paper describes the detailed and sophisticated numerical simulation performed for this full-scale test, following which the numerical predictions were compared with the experimental results. In the numerical model, the nonlinear behavior is concentrated at the RTWCs, which is simulated with the use of a multi-linear plastic element. The analysis was conducted on four sets of uplift loads applied during the physical testing: 30 m/sincreased by 5 m/sincrements to 45 m/s. At this level of uplift loading, the connections exhibited inelastic behavior. A comparison with the experimental results revealed the ability of the sophisticated numerical model to predict the nonlinear response of the roof under wind uplift loads that vary both in time and space. A further component of the study was an evaluation of the load sharing among the trusses under realistic, uniform, and code pressures. Both the numerical model and the tributary area method were used for the load-sharing calculations.

• Geomechanics and Engineering
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• 제10권5호
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• pp.577-598
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• 2016

This paper presents a numerical study of pile force distribution in a pile group foundation subjected to vertical load and large moment. The physical modeling of a pile foundation for a wind turbine is analyzed using 3D finite element software, PLAXIS 3D. The soil profile consists of several clay layers, which are modeled as Mohr-Coulomb material in an undrained condition. The piles in the pile group foundation are modeled as special elements called embedded pile elements. To model the problem of a pile group foundation, a small gap is created between the pile cap and underlying soil. The pile cap is modeled as a rigid plate element connected to each pile by a hinge. As a result, applied vertical load and large moment are transferred only to piles without any load sharing to underlying soil. Results of the study focus on pile load distribution for the square shape of a pile group foundation. Mathematical expression is proposed to describe pile force distribution for the cases of vertical load and large moment and purely vertical load.