• 한국전산구조공학회논문집
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• 제17권1호
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• pp.1-10
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• 2004

최근, 유한요소해석견과의 신뢰도를 향상시키기 위하여 활발하게 연구되고 있는 적응유한요소해석은 반복계산을 통해서 해석결과의 오차가 사용자에 의해 지정된 허용오차와 같아지도록 하는 해석방법이다. 이와 간은 적응유한요소해석은 해석결과의 오차평가와 이에 따른 유한요소의 재구성과정으로 나누어진다. rp방법에서는 절점의 위치를 이동시켜 요소의 크기를 조절하는 r방법과 형상함수찻수를 증가시키는 p방법을 동시에 적용함으로써 적응해석의 유효성을 향상시키고자 하였다. 제안한 rp방법의 특성을 규명하고 적응해석의 유효성을 보이기 위하여 전형적인 이차원 평면문제들을 해석하고 그 결과를 검토하였다.

• 한국도로학회논문집
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• 제15권3호
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• pp.159-167
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• 2013

PURPOSES: The purpose of this study is to develop an effectiveness analysis method of exclusive median bus lanes, which is necessary in order to improve operation efficiency of exclusive median bus lanes. METHODS : The operation characteristics of "signalized intersection including exclusive median bus lanes" and "normal signalized intersection" were investigated and the existing capacity analysis method was also reviewed to analyze the effectiveness of exclusive median bus lanes. Delay reduction of passengers using exclusive median bus lanes which can be considered as the benefit of exclusive median bus lanes and the number of people in buses were included in the proposed effectiveness analysis method. RESULTS : It was found that the proposed method expresses properly the effectiveness of exclusive median bus lanes through performing sensitivity analysis and analyzing with the real data of the number of people in buses and passenger cars. It was also found that the proposed method demonstrates the effectiveness that measure of effectiveness of signalized intersections is changed to "sec/person". CONCLUSIONS : It was concluded that the method is a proper effectiveness analysis method because it can reflect the benefit of passengers in buses.

• 한국압력기기공학회 논문집
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• 제13권2호
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• pp.38-43
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• 2017

This paper investigates how to determine the Rayleigh damping coefficients for dynamic time history seismic analysis of piping systems. Three methods are applied. The first one is a conventional method to use the natural frequencies of the mode 1 and 2, derived from dynamic analysis. The second method is to determine the Rayleigh damping coefficients based on frequency range of the acceleration histories. The last one is a iterative transient response analysis method using the transient analysis results without and with damping. It is found that the conventional method and the iterative transient response method yield the same results whereas the acceleration frequency-basis method provides more conservative result than the other methods. In addition, it is concluded that the iterative transient response method is recommended.

• 한국유체기계학회 논문집
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• 제15권4호
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• pp.55-60
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• 2012

The purpose of this study is to investigate the buckling load of filament-wound composite towers for large scale wind-turbine using finite element method(FEM). To define material properties, we used both the effective property method and the stacking properties method. The effective properties method is to assume that composite consists of one ply. The stacking properties method is to assume that composite consists of some stacked plies. First, linear buckling analysis of the tower, filament-wounded with angles of [${\pm}30$] was carried out by two methods for composite material properties, the stacking method and the effective method. and FE analysis was performed for the composite towers according to filament winding angles of [${\pm}30$], [${\pm}45$], [${\pm}60$]. FE analysis results using the stacking properties of the composite were in good agreement with the results by the effective properties. The difference between FEM results by material properties methods was approximately 0~2.3% in buckling Analysis and approximately 0~0.6% in modal analysis. And above the angle of [${\pm}60$], there was a little change of buckling load.

• Geomechanics and Engineering
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• 제15권6호
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• pp.1207-1217
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• 2018

Geomechanics parameters are critical to numerical simulation, stability analysis, design and construction of geotechnical engineering. Due to the limitations of laboratory and in situ experiments, back analysis is widely used in geomechancis and geotechnical engineering. In this study, a hybrid back analysis method, that coupling numerical simulation, response surface (RS) and relevance vector machine (RVM), was proposed and applied to identify geomechanics parameters from hydraulic fracturing. RVM was adapted to approximate complex functional relationships between geomechanics parameters and borehole pressure through coupling with response surface method and numerical method. Artificial bee colony (ABC) algorithm was used to search the geomechanics parameters as optimal method in back analysis. The proposed method was verified by a numerical example. Based on the geomechanics parameters identified by hybrid back analysis, the computed borehole pressure agreed closely with the monitored borehole pressure. It showed that RVM presented well the relationship between geomechanics parameters and borehole pressure, and the proposed method can characterized the geomechanics parameters reasonably. Further, the parameters of hybrid back analysis were analyzed and discussed. It showed that the hybrid back analysis is feasible, effective, robust and has a good global searching performance. The proposed method provides a significant way to identify geomechanics parameters from hydraulic fracturing.

• International Journal of Fluid Machinery and Systems
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• 제8권4호
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• pp.221-229
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• 2015

For efficient design process of regenerative blower, the present study provides new generalized pressure and leakage flow loss models, which can be used in the performance analysis method of regenerative blower. The present performance analysis on designed blower is made by incorporating momentum exchange theory between impellers and side channel with mean line analysis method, and its pressure loss and leakage flow models are generalized from the related fluid mechanics correlations which can be expressed in terms of blower design variables. The present performance analysis method is applied to four existing models for verifying its prediction accuracy, and the prediction and the test results agreed well within a few percentage of relative error. Furthermore, the present performance analysis method is also applied in developing a new blower used for fuel cell application, and the newly designed blower is manufactured and tested through chamber-type test facility. The performance prediction by the present method agreed well with the test result and also with the CFD simulation results. From the comparison results, the present performance analysis method is shown to be suitable for the actual design practice of regenerative blower.

• 한국지반신소재학회논문집
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• 제17권4호
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• pp.41-52
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• 2018

복합지반 설계법은 계산이나 수치해석시 적용하기 편리하여 시멘트혼합처리공법의 설계시 많은 설계자들에 의해 적용되고 있다. 그러나, 복합지반 설계법은 다짐말뚝공법(SCP, GCP)에 관하여 개발된 것으로 시멘트혼합처리공법에 대한 시험시공 등의 실제 결과와의 비교 분석은 미미하다. 본 연구에서는 2차원 유한요소 수치해석을 통해 복합지반 해석법, 개별말뚝해석법 등 다양한 해석법의 결과를 실측과 비교 분석하였다. 본 연구 결과, 지표면에서의 침하는 Plate 요소만을 적용하는 방법의 침하량이 실측에 비해 크게 예측되었고, 기타 방법은 유사한 것으로 나타났다. 개량지반 직하부에서만 발생된 침하량의 크기가 크게 나타났고, 침하량, 수평변위 및 지반반력 등에 대하여 실측과 수치해석 결과를 비교하면 등가벽 개념의 개별말뚝 해석법이 가장 유사한 것으로 나타났다. 복합지반법의 경우 응력전이(지반아칭) 현상을 예측하지 못하였고, 수평변위를 과대 예측하는 것으로 나타났다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 가을 학술발표회 논문집
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• pp.365-370
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• 1999

In this paper, dynamic response analysis on the ground movement applied traffic load by 2D finite element procedure has been studied. In particular, The paper deal with pointing acceleration method that applied AFIMEX Code as like 2D-FLUSH using equivalent linear method. As the result, it is found that dynamic response analysis by pointing acceleration method expressed ground movement by traffic load exactly.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 추계학술발표대회 논문집
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• pp.187-190
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• 2001

Response surface method is applied to evaluate the reliability of laminated composite panels. Since the linear and nonlinear first-ply failure load are computed using deterministic finite element analysis, new probabilistic finite element analysis is not necessary. Tsai-Wu criterion is used to construct the limit state suface. Material properties, layer thickness and lamina strengths of laminated composite panel are treated as random design variables. feasibility and accuracy of current method is validated using Monte-Carlo method Which perform thousand times of finite element analysis directly.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1654-1659
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• 2003

This paper introduces a fast Fourier transform (FFT)-based spectral analysis method for the transient responses as well as the steady-state responses of linear discrete systems. The force vibration of a viscously damped three-DOF system is considered as the illustrative numerical example. The proposed spectral analysis method is evaluated by comparing with the exact analytical solutions as well as with the numerical solutions obtained by the Runge-Kutta method.