• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.1
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• pp.1-14
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• 1999

선형탄성이론을 기초로 한 구조해석의 경우 사용하중상태에서의 변형과 응력은 만족할 만한 결과를 나타내지만, 항복후의 처짐과 파괴시의 극한하중 산정의 정확한 해석이 불가능하다. 평판의 극한해석시, 상한계 이론을 바탕으로 한 항복선 이론이 널리 사용되고 있으나 이론적으로 평판의 강도를 과대평가하게 된다. 그러므로, 임의의 하중조건과 경계조건에 대한 비선형 거동과 극한내하력을 산정할 수 있는 해석기법이 필요하다. 평판의 정확한 극한하중을 위해 p-Version 유한요소법을 제안하며, p-Version의 해석치를 범용 구조해석 프로그램인 ADINA의 결과와 문헌의 이론치와 비교하였다.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.117-120
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• 2008

The bridge bearings are devices absorbing the displacements of the superstructure. KS F 4420 relative to the design of elastomeric bearings in Korea allows shear deformation up to 70% of total rubber height. For the elastomeric bearings to fulfill their shear function required in the design, the stability of allowable shear strain of elastomeric bearings relative to the shear failure should be guaranteed. Moreover considering the possibility that elastomeric bearings are applied to the seismic design together with isolation devices, elastomeric bearings is supposed to display higher shear performance. In this paper ultimate shear performance tests were performed. The measured ultimate shear strains were over 200%. Therefore an allowable shear strain provision becomes safe. But elastomeric bearings expected to show their performance in one united body reveled the separation of components near 200% shear strain. These separation in elastomeric bearing can cause unexpected impact or concentrated stress to bridge system considering to application of seismic design. Therefore provision relevant to separation problem is necessary.

• KDI Journal of Economic Policy
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• v.16 no.3
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• pp.45-68
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• 1994

이 글에서는 Johansen의 공적분(共積分) 검정방법(檢定方法)을 사용하여 총통화수요함수(總通貨需要函數)의 장기적(長期的) 안정성(安定性)을 검토하였다. 검정결과, 총통화(總通貨)와 실질국민총생산(實質國民總生産), 그리고 회사채수익률(會社債收益率) 사이에 한 개의 공적분관계(共積分關係)가 존재하여 이들 변수들 사이에 안정적인 장기균충관계(長期均衝關係)가 성립하는 것으로 나타났다. 통화수요(通貨需要)의 실질소득(實質所得)에 대한 탄성치(彈性値)가 1이라는 가정은 기각되었으며, 균형으로부터의 일시적 이탈에 대한 조정은 실질소득(實質所得)이나 이자율(利子率)보다는 주로 실질통화수요(實質通貨需要)에 의해 이루어지는 것으로 판정되었다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.1
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• pp.87-95
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• 2000

The two eigenvalues (elastic critical load and natural frequency of lateral vibration) of sinusoidally tapered bats with simply supported ends were determined by the finite element method. For the convenience of structural engineers who are engaged in the structural design or vibration analysis of tapered beam-columns, eigenvalue coefficients were expressed by simple algebraic equations. The validity of each algebraic equation was confirmed by the value of unity for each correlation coefficient. The influence of axial thrust on the lateral vibration frequency was also investigated. For this purpose, the axial thrust was increased successively and the corresponding frequency was calculated. The approximate linear relationship between the axial thrust and the square of the frequency was confirmed lot each of the tapered members.

• The Journal of the Korean dental association
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• v.27 no.2 s.237
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• pp.161-169
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• 1989

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6106-6113
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• 2013

Automotive three-way catalyst substrate has a cordierite ceramic honeycomb structure. The substrate in the high engine speed range doesn't satisfy the design fatigue life due to the low mechanical properties of cordierite ceramic. SiC ceramic has higher mechanical properties than cordierite ceramic. If the automotive three-way catalyst substrate is made from the SiC ceramic honeycomb structure, the substrate can be prevented from premature failure. In this study, the mechanical properties of SiC ceramic honeycomb substrate were estimated by FEA. The FEA results indicated that the MOR and elastic modulus for the SiC ceramic honeycomb substrate was much higher than those for the cordierite ceramic honeycomb substrate.

• Geophysics and Geophysical Exploration
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• v.16 no.1
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• pp.1-5
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• 2013

Stacking in seismic processing plays an important role in improving signal-to-noise ratio and imaging quality of seismic data. However, the conventional stacking method doesn't remove random noises with various distributions and outliers up to a satisfactory level. This paper introduces a robust and optimum weighted stack method which shows both robustness to outlier noises and optimum in removing random noises. This was achieved by combining the robust median stacking with the optimum weighted stacking using local correlation. Application of the method to synthetic data showed that the proposed method is very effective in suppressing random noises with various distributions including outliers.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.3
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• pp.173-182
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• 2014

The mixed convolved action principle provides a new rigorous weak variational formalism for a broad range of initial boundary value problems in mathematical physics and mechanics in terms of mixed formulation, convolution, and fractional calculus. In this paper, its potential in the development of numerical methods for transient problems in various dynamical systems when adopting temporally second order approximation is investigated. For this, the classical single-degree-of-freedom linear elastic dynamical systems are primarily considered to investigate computational characteristics of the developed algorithms. For the undamped system, all the developed algorithms are symplectic with respect to the time step. For the damped system, they are shown to be accurate with good convergence characteristics.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.6
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• pp.351-356
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• 2022

In this paper, we present the regression analysis and design optimization for improving the permeability of 3D woven materials based on numerical analysis data. First, the parametric analysis model is generated with variables that define the gap sizes between each directional wire of the woven material. Then, material properties such as bulk modulus, thermal conductivity coefficient, and permeability are calculated using numerical analysis, and these material data are used in the polynomial-based regression analysis. The Pareto optimal solution is obtained between bulk modulus and permeability by using multi-objective optimization and shows their trade-off relation. In addition, gradient-based design optimization is applied to maximize the fluid permeability for 3D woven materials, and the optimal designs are obtained according to the various minimum bulk modulus constraints. Finally, the optimal solutions from regression equations are verified to demonstrate the accuracy of the proposed method.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.471-478
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• 2002

초음파를 사과의 비파괴 품질판정에 이용하기 위한 기초연구로서 계측된 저장기간에 따른 사과의 초음파 특성과 본 연구에서 계측된 사과의 기계적 특성을 이용하여 초음파에 의한 사과의 탄성계수 및 생물체항복강도 예측모델을 개발하고자 하였으며, 결론은 다음과 같다. 1. UTM을 이용하여 사과의 기계적 특성치를 분석하여 생물체항복점, 생물체항복변형량, 생물체항복강도, 파괴점, 극한변형량, 극한강도 및 탄성계수 등을 구하였다. 2. 사과의 기본 물성, 초음파 특성과 기계적 특성값 들을 분석한 결과 사과의 질량, 체적, 시간영역의 진폭(PTP), 제3영역 에너지 스펙트럼 밀도함수가 기계적 특성 중 생물체항복강도, 탄성계수와 높은 상관성이 있는 것으로 나타났다. 3. 사과의 저장 기간, 질량, 체적, Peak-to-peak, 제3영역의 에너지값 등 5개의 독립변수를 가지는 다중선형회귀모형으로 사과의 탄성계수 및 생물체 항복강도 예측모형을 개발하였다.