• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2001년도 추계학술대회 논문집
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• pp.132-137
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• 2001

This paper presents a method of seismic analysis for a 2-D fluid-structure-soil interaction systems. With this method, the fluid can be modeled by spurious free 4-node displacement-based fluid elements which use rotational penalty and mass projection technique in conjunction with the one point reduced integration scheme to remove the spurious zero energy modes. The structure and the near-field soil are discretized by the standard 2-D finite elements, while the unbounded far-field soil is represented by the dynamic infinite elements in the frequency domain. Since this method directly models the fluid-structure-soil interaction systems, it can be applied to the dynamic analysis of a 2-D liquid storage structure with complex geometry. Finally, results of seismic analyses are presented for a spent fuel storage tank embedded in a layered half-space and a massive concrete dam on a layered half-space.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.458-461
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• 2006

Early age cracking of concrete is a widespread and complicated problem, and diverse applications in practical engineering have focused on this issue. Since massive concrete base slab composes the infrastructure of other concrete structures such as pier, concrete dam, and high rise buildings, early age cracking of that is considered as a crucial problem. In this study, finite element analysis (FEA) implemented with the age-dependent microplane model was performed. For a massive concrete base slab, cracking initiation and propagation, and deformation variation were investigated with concrete age. In massive concrete slab, autogenous shrinkage increases the risk of early age cracking and it reduces reinforcement effect on control of early age cracking. Gradual crack occurrence is experienced from exterior surface towards interior of the slab in case of combined hydration heat and autogenous shrinkage. FEA implemented with enhanced microplane model successfully simulates the typical cracking patterns due to edge restraint in concrete base slab.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.190-193
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• 2005

The purpose of the present study is to design a 500W-class micro scale composite wind turbine blade. The blade airfoil of FFA-W3-211 was selected to meet Korean weather condition. The skin-spar-f Dam sandwich type structure was adopted for improving buckling and vibration damping characteristics. The design loads were determined at wind speed of 25m/s. and the structural analysis was performed to confirm safety and stability from strength. buckling and natural frequency using the finite element code. NISA II [6]. The prototype was manufactured using the hand-lay up method and it was experimently tested using the sand bag loading method. In order to evaluate the design results. it was compared with experimental results. According to comparison results. the estimated results such as compressible stress. max tip deflection natural frequency and buckling load factor were well agreed with the experimental results.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.939-944
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• 2003

The analysis involves an adaptive grid that is created under a criterion of element categorization of filling states and locations in the total region at each time step. By using an adaptive grid wherein the elements, finer than those in internal and external regions, are distributed at the surface region through refinement and coarsening procedures, a more efficient analysis of transient fluid flow with free surface is achieved. Using the proposed numerical technique, the collapse of a dam is analyzed. The numerical results agree well with the theoretical solutions as well as with the experimental results. Through comparisons with the numerical results of several cases using different types of grids, the efficiency of the proposed technique is verified.

• 한국농공학회지
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• 제42권3호
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• pp.76-88
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• 2000

AGNPS model is applied in this study to analyze the changes of non-point source pollutant according to AMC condition using probable rainfall. Probable rainfall of H-dam area by Gumber's extreme value distribution is computed through frequency analysis for each return period. 35 coarse grids are subdivided into 134 find grids of finite differential network to analyze peak flow soil loss quantity and nutrients of study area and the modified CN estimation equation shows good result about rainfall events-peak flow relationship. And as the consequence of estimation of soil loss quantity for each rainfall event soil loss quantity shows 120%-170% of actual soil loss quantity Regression analysis for the observed and calculated values of flow T-P AMC has an important effect on nutrients concentration of outflow and it if found that the excessive fertilization under AMC III condition may cause eutrophication by nutrients because the range of increase of outflow concentration appears relatively high.

• Smart Structures and Systems
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• 제20권6호
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• pp.759-767
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• 2017

Wear and aging associated damage is a severe problem for safety and maintenance of engineering structures. To acquire structural operational state and provide warning about different types of damage, research on damage identification has gained increasing popularity in recent years. Among various damage identification methods, the Lamb wave-based methods have shown promising suitability and potential for damage identification of plate-type structures. In this paper, a comprehensive study was presented to elaborate four remarkable aspects regarding the Lamb wave-based damage identification method for plate-type structures, including wave velocity, signal denoising, image reconstruction, and sensor layout. Conclusions and path forward were summarized and classified serving as a starting point for research and application in this area.

• 한국농공학회지
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• 제36권3호
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• pp.67-73
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• 1994

This paper is to validate the proposed models for the real-time forecasting for the Keum river estuary dam such as tidal-level forecasting model, one-dimensional unsteady flood routing model, and Kalman filter models. The tidal-level forecasting model was based on semi-range and phase lag of four tidal constituents. The dynamic wave routing model was based on an implicit finite difference solution of the complete one-dimensional St. Venant equations of unsteady flow. The Kalman filter model was composed of a processing equation and adaptive filtering algorithm. The processng equations are second ordpr autoregressive model and autoregressive moving average model. Simulated results of the models were compared with field data and were reviewed.

• 대한기계학회논문집B
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• 제24권12호
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• pp.1555-1569
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• 2000

Numerical simulation of fluid flow with moving free surface has been carried out. For the free surface flow, a VOF(Volume of Fluid)-based algorithm utilizing a fixed grid system has been investigated. In order to reduce numerical smearing at the free surface represented on a fixed grid system, a new free surface tracking algorithm based on the donor-acceptor scheme has been presented. Novel features of the proposed algorithm are characterized as two numerical tools; the orientation vector to represent the free surface orientation in each cell and the baby-cell to determine the fluid volume flux at each cell boundary. The proposed algorithm can be easily implemented in any irregular non-uniform grid systems that are usual in finite element method (FEM). Moreover, the proposed algorithm can be extended and applied to the 3-D free surface flow problem without additional efforts. For computation of unsteady incompressible flow, a finite element approximation based on the explicit fractional step method has been adopted. In addition, the SUPG(streamline upwind/Petrov-Galerkin) method has been implemented to deal with convection dominated flows. Combination of the proposed free surface tracking scheme and explicit fractional step formulation resulted in an efficient solution algorithm. Validity of the present solution algorithm was demonstrated from its application to the broken dam and the solitary wave propagation problems.

• 한국지반공학회논문집
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• 제15권3호
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• pp.27-40
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• 1999

사면안정해석을 수행하기 위하여 많이 사용하는 한계평형방법은 일정한 가정을 하여 안전율을 평형에 필요한 응력과 흙의 전단강도의 비로 정의하여 대상사면의 안전율을 구한다. 유한요소법을 이용한 사면안정해석방법은 응력상태를 유한요소법으로 구한 후 원호나 대수나선형등의 일정한 모양의 사면 파괴선을 가정하여 반복적으로 최소안전율을 구한다. 본 연구에서는 유한요소법을 이용한 사면안정해석방법을 개발하여 사면의 가장 취약한 부분을 따라 파괴선이 발생하도록 하였다. 이것은 요소내의 국부안전율과 파괴각을 고려하여 사면파괴선을 자동적으로 구할 수 있도록 함으로써 가능한데 이 방법은 임의의 파괴선을 가정할 필요가 없으며 절편에 작용하는 힘에 대하여 가정을 할 필요가 없고 임의의 모양의 파괴선을 구할 수 있는 장점이 있다. 본 연구에서는 개발된 해석방법을 검증하기 위하여 가상의 사면, 자연사면, 그리고 댐사면에 적용하여 실무에서 많이 사용하는 한계평형방법 프로그램인 STABL5M과 SLOPE/W과 비교 평가하였다.

• 한국수자원학회논문집
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• 제44권2호
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• pp.145-156
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• 2011

본 연구에서는 자연하천의 흐름에서 흔히 발생하는 천이류, 불연속류, 마른하도로의 파의 전파 등을 포함하는 복잡한 흐름을 해석하기 위한 고정확도 2차원 수치모형을 개발하였다. 하상경사항을 효율적으로 처리하기 위해 quasi-steady wave propagation 기법을 적용하여 해당 격자에 대한 생성항의 영향을 효율적으로 반영함으로써 쌍곡선형 적분 보존형의 2차원 천수방정식을 해석하였다. Fractional Step Method를 적용한 유한체적기법의 사용을 위해 HLL Riemann 해법을 이용하여 흐름률을 계산하였고, 시간 및 공간에 대한 2차 정확도를 만족하기 위해 MUSCL 기법을 적용하였다. 2차 정확도의 사용으로 불연속지점에서 발생하는 수치진동은 TVD 기법 적용을통해 제어하였다. 개발된모형은 2차원 제방 붕괴 및 댐하류부에 구조물이 존재하는 경우의댐 붕괴 모의를 통해실측치와의 검증을 실시하였다. 또한 하류부에 역경사가 존재하는 경우의 댐 붕괴 모의를 통해 실측치와 비교함으로써 생성항의 영향에 대한 모형의 적용성을 검증하였다.