• Earthquakes and Structures
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• 제12권2호
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• pp.251-262
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• 2017

The present research intends to study the effects of the seismic soil-foundation-structure interaction (SFSI) on the dynamic response of various buildings. Two methods including direct and Cone model were studied through 3D finite element method using ABAQUS software. Cone model as an approximate method to consider the SFSI phenomenon was developed and evaluated for both high and low rise buildings. Effect of soil nonlinearity, foundation rigidity and embedment as well as friction coefficient between soil-foundation interfaces during seismic excitation are investigated. Validity and performance of both approaches are evaluated as reference graphs for Cone model and infinite boundary condition, soil nonlinearity and amplification factor for direct method. A series of calculations by DeepSoil for inverse earthquake record modification was conducted. A comparison of the two methods was carried out by root-mean-square-deviation (RMSD) tool for maximum lateral displacement and story shear forces which verifies that Cone model results have good agreement with direct method. It was concluded that Cone method is a convenient, fast and rather accurate method as an approximate way to count for soil media.

• 한국전자파학회논문지
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• 제24권1호
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• pp.47-54
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• 2013

본 연구는 국내 최초로 개발된 직접 비교법을 이용한 W-band 밀리미터파 전력 표준 전달 시스템에 대한 것이다. 이 시스템은 75~110 GHz 대역에서 W-band 도파관형 전력감지기의 실효 효율과 교정 인자를 측정하기 위하여 개발되었다. 전력 표준 전달 시스템 구성의 핵심 요소인 방향성 결합기의 반사 특성 평가 기법을 소개하고 실험 결과를 보인다. 구현된 시스템을 이용하여 측정하고자 하는 전력감지기의 교정 인자 측정 결과를 보이고, 불확도 요인에 대하여 고찰한다. 측정 결과를 기준값과 비교하여 W-band 밀리미터파 전력 표준 전달 시스템에 의한 측정의 유효성을 검증한다.

• 한국재료학회지
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• 제16권2호
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• pp.85-91
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• 2006

The fraction of $\varepsilon\;and\;\gamma$'-iron nitride in compound layer is predicted by x-ray diffraction using direct comparison method. The validity of formulation models was checked by comparing calculated results with metallographic analysis of iron nitride compound layer grown on steel S45C by gas nitriding. The fraction of $\varepsilon$ calculated by the three phase model, porous-$Fe_3N$/ dense-$Fe_3N$/ mixed layer with $Fe_3N\;and\;Fe_4N$, is 80 percent of that analyzed by etching technique. The $\varepsilon$ fraction predicted by mixed layer model is 122 percent of that measured by microscope.

• 복식
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• 제53권5호
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• pp.1-12
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• 2003

This paper proposes a system for measuring the 3D human bodies using the multiple 2D images. The system establishes the multiple image input circumstance from the digital camera for image measurement. The algorithm considering perspective projection leads us to estimate the 3D human bodies from the multiple 2D images such as frontal. side and rear views. The results of the image measurement is compared those of the direct measurement and the 3D scanner for the total 40 items (12 heights, 15 widths and 13 depths). Three persons measure the 40 items using the three measurement methods. In comparison of the results obtained among the measurement methods and the persons, the results between the image measurement and the 3D scanner are very similar. However, the errors for the direct measurement are relatively larger than those between the image measurement and the 3D scanner. For example, the maximum errors between the image measurement and the 3D scanner are 0.41cm in height, 0.39cm in width and 0.95cm in depth. The errors are acceptable in body measurement. Performance of the image measurement is superior to the direct. because the algorithm estimates the 3D positions using the perspective projection. In above comparison, the image measurement is expected as a new method for measuring the 3D body, since it has the various advantages of the direct measurement and 3D scanner in performance for measurement as well as in the devices, cost, Portability and man power.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제26권4호
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• pp.333-342
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• 2022

In this paper, we perform a direct comparison study of real experimental data for domain rearrangement and the Cahn-Hilliard (CH) equation on the dynamics of morphological evolution. To validate a mathematical model for physical phenomena, we take initial conditions from experimental images by using an image segmentation technique. The image segmentation algorithm is based on the Mumford-Shah functional and the Allen-Cahn (AC) equation. The segmented phase-field profile is similar to the solution of the CH equation, that is, it has hyperbolic tangent profile across interfacial transition region. We use unconditionally stable schemes to solve the governing equations. As a test problem, we take domain rearrangement of lipid bilayers. Numerical results demonstrate that comparison of the evolutions with experimental data is a good benchmark test for validating a mathematical model.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2004년도 추계학술대회 논문집
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• pp.302-303
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• 2004

• 방송공학회논문지
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• 제21권1호
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• pp.76-86
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• 2016

연구에서는 입체시 측정방법과 양안시차에 따라 지각되는 입체시 깊이 차이를 살펴보기 위해서 실시되었다. 직접비교 조건에서는 깊이를 평가할 가상자극과 깊이 평가에 사용된 실제 LED들이 모두 정면의 동일 공간에 제시되어 있었고, 간접비교 조건에서는 가상자극은 정면에 제시되었지만 깊이 평가에 사용된 LED들은 45도 오른쪽에 놓여있었다. 따라서 직접비교 조건에서는 동일 공간에 제시된 두 자극의 깊이를 비교하면서 대응시킬 수 있었지만, 간접비교 조건에서는 가상 자극의 깊이를 평가한 후 오른쪽 방향에 있는 LED를 이용하여 깊이를 추정할 수 있었다. 이 들 두 측정 방법에서 지각되는 입체시 깊이가 달라지는 지를 확인하고 부가적으로 관찰자들의 입체시력에 따라 지각되는 깊이가 달라지는 지를 살펴보았다. 실험 결과 직접비교 조건에서 지각된 깊이는 간접비교 조건에서 지각된 깊이보다 더 기하학적으로 예측된 깊이와 유사하였다. 또한 입체시력이 좋은 사람들은 그렇지 않은 사람들보다 기하학적으로 예측된 깊이와 유사한 깊이를 지각하였다. 이러한 결과는 동일한 양안 시차를 가진 자극들이라도 이들 가상자극들만 제시되는 것보다 현실자극과 가상자극이 동일 공간에 제시될 때 지각된 깊이가 더 크게 지각됨을 보여주는 것이다. 따라서 양안시차를 가진 자극만 제시되는 가상현실에서 지각되는 입체 자극의 깊이보다 현실영상과 가상영상이 함께 제시되는 증강현실에서 보다 큰 깊이가 지각될 수 있음을 시사한다.

• 한국소음진동공학회논문집
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• 제20권5호
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• pp.477-485
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• 2010

In this study, we suggested several approaches to evaluate the collision acceleration of a carbody under the article 16 of the Korean rolling stock safety regulations. There are various methods to evaluate the rigid body accelerations such as the displacement comparison method by double integration of filtered acceleration data, the velocity comparison method by direct integration of filtered acceleration data, and the analysis method of a velocity-time curve. We compared these methods one another using the 1D dynamic simulation model of Korean high-speed EMU composed of nonlinear springs or bars, dampers, and masses. From the simulation results, the velocity-time curve analysis method and the displacement comparison method are recommended to filter high frequency oscillations and evaluate the maximum and average accelerations of a carbody after a train collision.

• 기술혁신학회지
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• 제13권3호
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• pp.446-458
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• 2010

세계 각국은 과거부터 경제성장과 성장동력의 확보를 위해 꾸준히 외국인직접투자를 유치해왔으며 이는 우리나라도 예외가 아니다. 실제로, 각종 정책적 지원을 통해 양질의 투자를 유치하고 있고, 정부차원에서도 하나의 성과로 홍보하고 있다. 기존의 연구가 대부분 국가경제적 차원에서 외국인직접투자의 성과를 분석하고 있는 것에 그치고 있는 것에 착안, 본 연구는 이러한 외국인직접투자가 기업의 경영성과와 혁신성과에 긍정적인 효과를 미칠 것으로 가정하고 PSM 방법을 통해 실증분석을 하였다. 분석결과 매칭 전에는 외국인직접투자가 경영성과와 혁신성에 모두 양(+)의 효과를 미치는 것으로 나타났으나, 매칭 후에는 모두 통계적 유의성을 상실하여 외국인직접투자가 기업에 미치는 긍정적인 효과가 생각보다 부진하다는 것을 알 수 있었다. 이러한 분석결과는 정부의 외국인직접투자 인센티브 효과가 기대했던 것에 비해 적으며, 추후 정책에 대한 개선이 필요한 것으로 판단할 수 있다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.356-363
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• 2004

In this research, the shear behavior of four different interfaces consisting of 4 types of geosynthetics was examined, and both static and dynamic tests for the geosynthetic interface were conducted. The monotonic shear experiments were performed by using an inclined board apparatus and large direct shear device. The interface shear strength obtained from the inclined board tests were compared with those calculated from large direct shear tests. The comparison results indicated that direct shear tests are likely to overestimate the shear strength in low normal stress range where direct shear tests were not performed. Curved failure envelopes were also obtained for interface cases where two static shear tests were conducted. By comparing the friction angles measured from three tests, i.e. direct shear, inclined board, and shaking table tests, it was found that the friction angle might be different depending on the test method and normal stresses applied in this research. Therefore, it was concluded that the testing method should be determined carefully by considering the type of loads and the normal stress expected in the field.