• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.36 no.4
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• pp.255-262
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• 2018

In order to determine the three-dimensional position in photogrammetry, a spatial resection is a pre-requisite step to determine exterior orientation parameters. The existing spatial resection method is a non-linear equation that requires initial values of exterior orientation parameters and has a problem that a gimbal lock phenomenon may occur. On the other hand, the spatial resection using quaternion is a closed form solution that does not require initial values of EOP (Exterior Orientation Parameters) and is a method that can eliminate the problem of gimbal lock. In this study, to analyze the stability of the quaternion-based spatial resection, the exterior orientation parameters were determined according to the different layout of control points and were compared with the determined values using existing non-linear equation. As a result, it can be seen that the quaternionbased spatial resection is affected by the layout of the control points. Therefore, if the initial value of exterior orientation parameters could not be obtained, it would be more effective to estimate the initial exterior orientation values using the quaternion-based spatial resection and apply it to the collinearity equation-based spatial resection method.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.1 no.1
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• pp.71-80
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• 1989

In this paper, the concept of the infinite element is applied to the linear wave diffraction and radiation problems. The hydrodynamic pressure forces are assumed to be inertially dominated, and viscous effects are neglected. The near field region surrounding the solid body is modelled using the conventional finite elements, and the far field region is represented using the infinite elements .In order to represent the scattered wave potentials in the far field region more accurately, the infinite elements are developed using special shape functions derived from the asymptotic expressions for the analytical eigenseries solution of the scattered waves. The system matrices of the infinite elements are constructed by performing the integration in the infinite direction analytically to achieve computational efficiency. Numerical analyses are carried out for vertical axisymmetric bodies to validate the infinite elements developed here. Comparisons with the results by other available numerical solution methods show that the present method using the infinite elements gives fairly good results. Numerical experiments are per-formed to determine the suitable location of the infinite elements and the appropriate size of the finite elements which directly affect accuracy and efficiency of the solution.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.4
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• pp.251-257
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• 2023

This study entailed an investigation of a tensile stress measurement method for prestressed concrete (PSC) tendons by utilizing external magnetization. The target of this study are PS structures that have been constructed and in use. An optimal external magnetization based elasto-magnetic (EM) sensor was designed using finite element analysis considering various factors, such as coil arrangement and size, that could influence the PS tendons inside the PSC girder. The residual tensile stress resulting from the external magnetization of the girder was then determined. Further, theoretical verification was performed using the numerical and material data used in the finite element analysis for sensor design. The calculated values of strength of magnetization at the target location were matched with the finite element analysis results. Thus, the designed sensor and the feasibility of magnetizing the tendons inside the PSC I-girder using an EM sensor were validated.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2008.10a
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• pp.358-363
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• 2008

최근 아날로그 항공사진카메라는 디지털방식으로 급속히 변화하고 있어 이에 따른 다양한 실험연구가 수행되고 있다. 디지털 카메라는 CCD의 구조와 촬영방식에 따라 크게 면형방식(area array)과 선형방식(line array)으로 구분되며 기술적으로 서로 상이한 원리로 영상을 취득하고 있다. 본 논문에서는 블록 조정에 횡스트립을 추가하여 블록 조정하였을 때 안정성에 얼마나 큰 영향이 있는지 알아보았다. 본 논문은 촬영시 추가한 횡스트립이 블록기하의 안정성에 미치는 영향을 검증하기 위하여 블록조정 결과에 따른 외부표정요소의 정확도를 비교 분석하였다. 연구결과 횡스트립을 추가하였을 때는 외부표정요소의 정확도가 크게 향상됨을 알 수 있었다. 향후 디지털 카메라에 의한 촬영시 적절한 중복도와 횡스트립의 배치간격 등에 대한 연구가 계속해서 이루어져야 될 것으로 판단된다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.3
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• pp.209-214
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• 2012

Recently, there were significantly increased cracks failure for external fuel tank horizontal fin of F-5 aircraft. In this paper, the dynamic behavior of horizontal fin was to quantitate by using Finite Element Method. To achieve this goal, the fatigue analysis for time and frequeucy domain has been performed by using the dynamic load spectrum of speed brake. In conclusion, it was proved that fatigue life of the horizontal fin was reduced by the influence of dynamic behavior.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.3
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• pp.303-314
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• 2010

A study for the nonlinear analysis method of prestressed concrete(PSC) girders with external tendons is presented. The PSC girders with external tendons show the complex nonlinear behavior due to the slip of external tendons at deviator and the change of eccentricity between the girders and external tendons. The external tendon between anchorage-deviator or deviator-deviator is modeled as an assemblage of the curved elements. The slip effect of the external tendon at deviator is taken into account using the force equilibrium relationship between the friction force and the driving force at each deviator. The finite element model and analysis method of the external tendon suggested herein are integrated in the nonlinear analysis program of segmentally erected PSC frames developed by the authors. The proposed analysis method is verified through the comparison of the analysis and experimental results obtained from other investigators. From the ultimate analysis results of PSC beams with external tendons having different number of deviators, the yielding and ultimate loads of PSC beams found to be increased as the number of deviators are increased. In addition, the ultimate capacity of the PSC beam increases according to the increase of friction coefficient between deviator and external tendon, whereas found to decease over the certain value of friction due to the effect of the moment transmitted to the member by the friction force exerted from the external tendon.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.34 no.3
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• pp.291-297
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• 2016

Direct georeferencing has become widespread in the field of digital aerial photogrammetry; as a result, the boresight calibration has become an essential component of the procedure to calculating exterior orientation parameters of aerial photographs accurately. During this procedure, a reference is used for the height of the geoid model, and the calibration results can appear different depending on the geoid model. The exterior orientation parameters calculated through direct georeferencing during boresight calibration may have varied values according to the corresponding geoid model. With that in mind, the effects of the geoid model on the boresight calibration were analyzed through three different cases. The geoid models used in the experiments were EGM96, EGM08, and KNGeoid14, and, through boresight calibration, the datum shift and boresight angle for each model was computed. After calculating the exterior orientation of each case, the GCP (Ground Control Point) was verified using the DPW (Digital Photogrammetry Workstation). In each case, results in the boresight calibration acquired through the geoid model demonstrated a difference in the Z datum, the exterior orientation heights Z, and the rotation Ω and Φ. After utilizing the DPW in each case and comparing it to the GCP, the difference in accuracy in accordance with the geoid model was found to be within 3cm, and it was concluded that the geoid model did not have a significant impact on boresight calibration.

• Journal of the Korean Geotechnical Society
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• v.36 no.11
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• pp.107-117
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• 2020

Open-ended steel pipe piles have outside frictional force and inside frictional resistance in which blocked soil acts on the inside of the steel pipe during installation. It is expected that the ultimate load will change depending on the inside and outside resistance. And, if the ground on which the piles were constructed is clay soil, it is predicted that it will have effect on the negative skin friction caused by the ground settlement. Therefore, in this study, the behavior according to the inside and outside resistance characteristics of steel pipe piles was analyzed numerically, and the frictional force distribution, axial load and settlements before and after the occurrence of ground settlement were calculated. As a result of the analysis, the inside frictional resistance had less influence than the outside frictional resistance. However, inside frictional resistance is considered to be one of the important factors considering the effect on the overall pile behavior, and both resistance factors need to be considered in the design process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.709-713
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• 2017

In urgent situations such as crashes, the integrity of an aircraft's fuel tank is directly related to the survivability of the crew. Thus, an external auxiliary fuel tank should be robust against bird strikes. In this study, a numerical analysis was carried out using impact analysis software to analyze the influence of bird strike on a composite container for an external auxiliary fuel tank. The structure was modeled as a shell element, and the fluid and bird were modeled by the particle method. The behavior of the internal fluid was also examined. The maximum stress, deformation, and strain of the composite container were also calculated.

• Science of Emotion and Sensibility
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• v.1 no.1
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• pp.113-122
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• 1998

인간의 감성은 감정과는 구분되는 심리적 현상으로, 감정이 강도가 높으며 생리적, 신체적 반응을 동반하는데 비하여, 감성은 강도가 낮으며 겉으로 나타나는 생리적 변화가 없다. 감정은 외부의 감각자극에 대하여 두뇌에서 단계적인 정보처리의 결과로 나타나지만 감성은 반사적이고 직관적으로 발생된다. 감정은 하나의 대상에 대하여 여러사람이 유사한 반응을 보이는 공통성과 객관성을 갖지만, 감성은 동일한 대상에 대해서도 개인에 따라 다양하게 나타나며 시간과 환경에 따하서도 변화한다. 감정은 일반성, 객관성, 반복성과 같은 학문적 연구대상으로서의 조건을 만족시키고 있으나, 감성은 그 특성이 학문이나 연구의 대상이 되기 위한 조건들을 충족시키지 못하며, 따라서 연구대상으로 인정받지 못하고 있다. 감성이 감정에 비하여 가장 두드러지는 점은 감정의 종류가 외부자극의 종류에 따라 결정되어지는 반면 감성의 발생은 개인의 재부상태, 즉 생활경험에 의한 기억에 의존한다는 점이다. 감성의 개인성, 변화성, 불확실성, 애매모호성등을 설명할 수 있기 위해서는 기존의 학문이 갖는 폐쇄성에서 벗어나 보다 많은 변수를 체계적이고 다각적으로 고려하는 새로운 접근이 필요하다. 학문과 연구대상에 대한 조건의 확대가 요구된다고 할 수 있다. 개인의 감성은 해당 시점에서 개인이 갖고 있는 심리상태와 함깨 연령, 성별, 교육정도, 건강상태와 같은 개인요소뿐만 아니라 개인의 의식과 생활에 영향을 미치는 가정과 사회특성, 나아가 전통과 관습, 종교, 환경등와 같은 문화적 특성에 의해서도 변화된다. 그리고 이들 요소들을 개인이 처한 상황에 따라 영향의 정도가 다양하게 변화한다. 많은 요인들에 의하여 다양하게 변화되는 감성은 감성의 영향을 받는 생활환경과 결합되고, 생활경험을 중심으로 한 기억은 두뇌의 Limbic system은 자율신경계를 조절하는 hypothalamus와 밀접한 관계를 갖고 있다. 따라서 감성의 측정평가를 위해서는 생활경험에 영향을 미치는 제반 요인들의 파악과 함께 자율신경계의 반응을 측정할 수 있는 방법의 개발이 요구된다.