• Magazine of the Korea Concrete Institute
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• v.11 no.1
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• pp.99-107
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• 1999

In this paper, the prediction method of the differential column shortening for cracked reinforced concrete tall buildings due to the construction sequence is presented. The cracked sectional properties from the strain and curvature of the sectional centroid is directly used. And the stiffness matrix of concrete elements considering the axial strain-curvature interaction effect is adopted. The creep and shrinkage properties used in the predictions were calculated in accordance with ACI 209, CEB-FIP 1990, and B3 model code. In order to demonstrate the validity of this algorithm, the prediction by the proposed method are compared with both the results of the in-situ test and the results by other simplified method. The proposed method is in good agreement with experimental results, and better than the simplified method.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.4
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• pp.48-59
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• 1996

The numerical step in the unsteady viscous flow analysis can be divided in the space analysis step satisfying continuity equation and the time marching step. In this study the spectral method is applied to solve the pressure Poisson equation in the space analysis step. If the highest order differential term of the pressure Poisson equation is transformed by Fourier series, pressure arid its first derivatives can be expressed by the integral form of Fourier series. So Gibb's phenomena can be eliminated and the spectral method can be applied to non-periodic problems. The numerical analysis of unsteady viscous flow around 2-dimensional circular cylinder and wing is carried out and compared for verification.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.4
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• pp.1-10
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• 2001

The 3-step cell search has been considered for fast acquisition of the scrambling code unique to a cell in the W -CDMA system. In this paper, the performance of the cell search scheme is analyzed in Rayleigh fading channels. And the system parameters for cell search scheme and the design parameters for the receivers are examined. The probabilities of detection, miss and false alarm for each step are derived in closed forms based on the statistics of CDMA noncoherent demodulator output. Through the analysis, the effect of threshold setting and post detection integration for each step is investigated, and the optimal values of the power allocation for the synchronization channels are also considered. The number of post-detection integrations for each step is a design parameter for the receiver, and the optimum values may depend on not only the power allocation for each channel related to the cell search, but the false alarm penalty time. It is shown that optimal values could be determined through the analysis. Also, the cumulative probability distribution of the average cell search time is obtained.

• Journal of the Earthquake Engineering Society of Korea
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• v.1 no.1
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• pp.1-10
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• 1997

Current seismic design philosophy for reinforced concrete (RC) structures on energy dissipation through large inelastic defomations. A nonlinear dynamic analysis which is used to represent this behavior is time consuming and expensive, particularly if the computations have to be repeated many times. Therefore, the selection of an efficient yet accurate alogorithm becomes important. The main objective of the present study is to propose a new technique herein called the prediction approach with siffness measure (PASM) method in the convetional direct integration methods, the triangular decomposition of matrix is required for solving equations of motion in every time step or every iteration. The PASM method uses a limited number of predetermined decomposed effective matrices obtained from stiffness states of the structure when it is deformed into the nonlinear range by statically applied cyclic loading. The method to be developed herein will reduce the overall numerical effort when compared to approaches which recompute the stiffness in each time step or iteration.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.37 no.1
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• pp.25-31
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• 2024

This paper introduces a numerical analysis model capable of evaluating CFT (Concrete-Filled Tube) columns across all time stages, incorporating creep behavior analysis and inelastic analysis to account for time-dependent behavior. The proposed model is compared with experimental results, revealing that the numerical model presented in this paper demonstrates more accurate trends than existing design criteria. Following verification, a numerical analysis is conducted for each slenderness ratio, determining the ultimate load capacity and examining the short-term and long-term sustained load behavior of the overall CFT column members.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.2
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• pp.147-155
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• 2013

In this paper structural analysis of underground electrical power cable structures which is excavated below the surface of the earth in the downtown area is carried out considering the effect of construction sequence. There are many various life-line facilities below the surface of the earth in the downtown area. MPDAP was used for finite element analysis of underground electrical power cable structures. Three typical sections are simulated by finite element models. Unbalanced equilibrium problems may be occurred when conventional finite element procedures were used for simulation of tunnel excavation. Therefore equilibrium perturbation concept was applied to solve these problems. The effects of time-dependent deformations in advancing tunnel excavation are considered in the stages of construction sequences as using the load distribution factor. It is shown that values of maximum displacement of both soil and rock surrounding underground electrical power cable structures obtained by our numerical studies are less than allowable values.

• 전기의세계
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• v.39 no.3
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• pp.55-60
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• 1990

최근의 값싸고 빠른 컴퓨터의 등장에 힘입어, 전자파 산란 및 전자파 장해의 수치 해석이 활발히 활용되고 있다. 보다 정확한 해석 및 설계를 위하여, 초기의 2차원 해석에서 벗어나, 3차원 벡터 해석이 보편화 되고 있는 데, 이에 부수되는 개영역 처리문제, 벡터변수 처리기법 및 컴퓨터 기억용량의 효율적인 사용등에서도 괄목할만한 진전이 있었다. 따라서 복잡한 구조의 전자파 문제를, 시험제작, 측정 및 수정설계라는 개발단계의 대부분을 컴퓨터를 이용하는 수치해석으로 대신할 수 있게 됨으로써, 시간과 자금과 노력을 극소화 시킬 수 있게 되었다.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.313-315
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• 2000

본 논문에서는 프랜트 설계 단계에서 안정도 해석을 행함에 있어 부하모델의 차이가 안정도 해석 결과에 미치는 영향을 비교 평가하였다. 플랜트 부하의 대부분인 유도전동기 모델을 달리 적용함에 따라 안정도 해석 시 최대 허용 고장제거시간이 매우 다르게 나타난다는 것을 보여 주었다. 또한 유도전동기의 모델 표현을 달리함에 따라 고장제거 후 모선의 전압회복 특성과 전동기 속도 회복 특성이 매우 달라짐을 보여 주면서 산업플랜트 보호계전 시스템 설계를 위한 안정도 해석 시 유도전동기 모델 적용방법에 있어 유의하여 할 사항을 제시하였다.

• Journal of Korean Society of Steel Construction
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• v.20 no.2
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• pp.303-312
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• 2008

In this paper, the seismic behavior of shear wal-frame systems is analyzed. The governing equations of the wall-frame systems with outrigger truss are formulated through the continuum approach and the whole structure is idealized as a shear-flexural cantileverwith rotational spring. The effect of shear deformation and flexural deformation of the wall-frame and outrigger trusses are considered and incorporated in the formulation of the wall-frame structures with and without outriggers are compared by using finite element analysis incorporated with the Newmark-${\beta}$ method. Numerical results are obtained and compared with the finite element package MIDAS. The proposed method is found to be simple and efficient, and provides reason ably accurate results in the early design stage of tall building structures.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.3
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• pp.317-327
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• 2001

In this paper, a relation to calculate design moments for reinforced concrete(RC) bridges constructed by movable scaffolding system(MSS) is introduced. Through the time-dependent analysis of RC bridges considering the construction sequence, the structural responses related to the member forces and deflections are reviewed, and a governing equation for determination of the design moment, which includes the creep deformation, is derived on the basis of the displacement-force condition at every constructuion stage. By using the relation, the design moment and its variation over time can easily be obtained only with the elastic analysis results without additional time-dependent analysis. In addition, correlation studies with the results by rigorous numerical analyses are conducts to verify the applicability of the introduced relation, and a more reasonable guideline for the determination of design moments is proposed on the basis of the obtained moment envelop.