• Geophysics and Geophysical Exploration
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• v.10 no.4
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• pp.252-258
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• 2007

We have studied the feasibility of geostatistics approach to enhancing analysis of sparsely obtained seismic data by combining with satellite gravity data. The shallow depth and numerous fishing nets in The Yellow Sea, west of Korea, makes it difficult to do seismic surveys in this area. Therefore, we have attempted to use geostatistics to integrate the seismic data along with gravity data. To evaluate the feasibility of this approach, we have extracted only a few seismic profile data from previous surveys in the Yellow Sea and performed integrated analysis combining with the results from gravity data under the assumption that seismic velocity and density have a high physical correlation. First, we analyzed the correlation between extracted seismic profiles and depths obtained from gravity inversion. Next, we transferred the gravity depth to travel time using non-linear indicator transform and analyze residual values by kriging with varying local means. Finally, the reconstructed time structure map was compared with the original seismic section given in the previous study. Our geostatistical approach demonstrates relatively satisfactory results and especially, in the boundary area where seismic lines are sparse, gives us more in-depth information than previously available.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1994.10a
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• pp.300-305
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• 1994

차실 음향 공동의 특성을 유한요소법에 의해 해석하고자 할 때, 과거에는 차실 음향공동과 트렁크 음향공동과의 상호연성을 고려하지 않고, 두 공동의 경계면을 강체 경계조건으로 생각하여 해석 대상 모델을 차실 음향 공동만으로 국한시켰다. 이러한 해석 방법을 통해서는, 차실과 트렁크 공동이 완전히 밀폐되어 있지 않고 단지 뒷좌석에 의해 두 공동이 구별되어지는 차종에 대해서는 실험과 근접하는 유한요소해석 결과를 얻을 수 없다. 그러므로 차실 공동과 트렁크 공동의 경계면을 가상의 탄성벽 경계조건으로 생각하여 그 탄성벽을 통한 두 공동의 상호 연성을 고려하는 유한요소 모델을 구현하여야 한다. 실제로 트렁크가 차실에 미치는 연성효과를 고려하여 유한요소해석을 수행할 경우 차실의 고유진동수와 고유모드에 미치는 영향이 상당히 큰 것을 확인할 수 있었다. 이하 본 내용에서는 차실과 트렁크 공동, 그 사이의 탄성벽을 이론적으로 해석 가능한 1차원으로 모델링하여 실험 결과와 근접하는 3차원 유한요소 모델링 기법을 제시한다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.319-322
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• 2002

그라우팅으로 지반 개량된 조간대 퇴적층의 지층구조를 규명하기 위한 방법으로 전기비저항탐사, 굴절법 탄성파탐사, 지하레이더탐사를 실시하였다. 연구대상 지반의 10m 전후 심도에서 해수의 영향을 받는 수평의 저비저항대가 발달하며, 저비저항대는 모래가 우세한 지층에 해당한다. 지반의 탄성파 속도는 1~3km/sec의 범위로 조간대의 미고결 퇴적층과 비교할 때 매우 높은 속도에 보여준다. 지반의 높은 속도는 지반 개량의 효과로 판단된다. 지하레이더탐사에서 퇴적층의 구성 물질에 따라 교반 정도가 달지는데 모래층은 퇴적물과 주입제의 교반이 잘 이루어져 불규칙한 반사면으로 나타나며, 점토층은 교반이 불량하여 개량된 부분은 주상으로 관찰된다. 물리탐사의 결과와 시추조사를 대비할 때 지반 개량은 기반암까지 시행되었으며, 양호한 암반을 지시하는 고비저항대와 고속도층은 내륙으로 갈수록 깊은 심도를 보여준다. 이것은 지반 개량 이전의 기반암 심도와는 상반되는 것으로 지반 개량의 효과는 해안방면의 지층에서 잘 나타난다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.3
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• pp.47-58
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• 1991

This paper presents dynamic infinite elements for soil-structure interaction analysis. In order to discretize the far field of the unbounded soil media, axisymmetric infinite elements which are capable of propagating multi-waves are proposed. An efficient numerical integration scheme for constructing the element characteristic matrices of the infinite elements in developed based on Gauss-Laguerre quadrature. The efficiency of the infinite elements is demonstrated by comparing the computed impedances of rigid circular footings on an elastic half space and on a layered half spaces with those obtained analytically.

• Journal of Digital Convergence
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• v.14 no.3
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• pp.489-497
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• 2016

The purpose of this study is to examine the effect of milk protein intake and band exercise on active fitness and metabolism risk factor of elderly women for 8 weeks. The two groups were classified into one group(TG) with milk protein intake and band exercise both, and the other group(CG) that was controled. The group of TG was applied doing milk protein intake 3 times for a day, and doing band exercise 4 times for 60 minutes a week. The intensity of the exercise was RPE<17. Each measurement variable was measured before and after 8 weeks to investigate the effect. This study got the result with this step. First, TG has shown small interaction with active fitness. Second, TG has shown small interaction with metabolism risk factor. Therefore, this study gives us the positive result of the effect of milk protein intake and band exercise on active fitness and metabolism risk factor of elderly women for 8 weeks. However, it has limitation to verify effect of milk protein intake and band exercise.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.2
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• pp.146-154
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• 2010

The effects of severe plastic deformation, equal channel angular pressing, and annealing of Al 5052 alloy on elastic modulus have been studied. The AI 5052 alloy was plastically deformed by ECAP method after solution treatment, and then finally annealing heat treated. Elastic modulus was measured by conventional tensile and nano-indentation test, and also measured on the surface of the specimen using acoustic material signature of the acoustic microscope. The variation in the elastic modulus influenced by plastic deformation and heat treatment, inaccessible by the conventional techniques, was successfully measured by acoustic material signature and obtained the elastic modulus depending on crystal orientation at each grain.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.5A
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• pp.361-367
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• 2011

This study introduces an elastic parabolic cable element for initial shaping analysis of cable-supported structures. First, an elastic catenary cable theory is shortly summarized by deriving the compatibility condition and the tangent stiffness matrices of the elastic catenary cable element. Next, the force-deformation relations and the tangent stiffness matrices of the elastic parabolic cable elements are derived and discussed under the assumption that sag configuration under self-weights is small. In addition the equivalent cable tension is defined in the chord-wise direction. Finally, to demonstrate the accuracy of the elastic parabolic cable element, nonlinear relationships of nominal cable tension-chord length and nominal cable tension-tangential stiffness for a single element are presented and compared with results using an elastic catenary cable theory as the slope is varied.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.7
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• pp.3207-3215
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• 2012

In this paper, we study the bending and free vibration analysis of nano plate, using a nonlocal elasticity theory of Eringen with a third-order shear deformation theory. This theory has ability to capture the both small scale effects and quadratic variation of shear strain and consequently shear stress through the plate thickness. Analytical solutions of bending and vibration of a laminated composite nano plate are presented using this theory to illustrate the effect of nonlocal theory on deflection of the nano plates. The relations between nonlocal third-order and local theories are discussed by numerical results. Further, effects of (i) nonlocal parameters, (ii) laminate schemes, (iii) directions of the fiber angle and (iv) number of layers on nondimensional deflections are investigated. In order to validate the present solutions, the reference solutions are used and discussed. The results of anisotropic nano plates using the nonlocal theory may be the benchmark test for the bending analysis.

• Composites Research
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• v.25 no.2
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• pp.34-39
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• 2012

A thermo-poro-elastic constitutive model of unidirectionally fiber-reinforced composite materials is suggested by extending the unmixing-mixing scheme which is based upon composite micromechanics. The strain components of thermal expansion due to a temperature change, gas pressure in pores, and chemical shrinkage are included in the constitutive model. On purpose to verify the derived constitutive relations, the representative volume element of two-dimensional lamina subject to various loading conditions is analyzed by the finite element method. The overall stress and strain responses are obtained, and compared with the predicted values by the unmixing-mixing scheme. The numerical results show the usefulness of the proposed model to predict the thermoelastic behavior of porous composites.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.6
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• pp.75-82
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• 2006

Tiltrotor aircraft can fly about twice faster and several times further than conventional helicopters. These aircraft provide advantages preventing compressibility of advancing side and stall of retreating side of blades because they take forward flight with tilting rotor systems. However, they have limit on forward flight speed because of the aeroelastic instability known as whirl flutter. First, the parametric study on the aeroelastic stability of the isolated rotor system has been performed in this paper. And the effects of pitch-link stiffness, gimbal spring constant, and precone angle on the whirl flutter stability of Smart-UAV have been investigated through CAMRAD II analysis.