• Structural Engineering and Mechanics
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• 제63권1호
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• pp.23-35
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• 2017

A nonlinear static procedure considering work-energy principle and global failure mechanism to estimate base shears of reinforced concrete (RC) frame-type structures is presented. The relative energy equation comprising of elastic vibrational energy, plastic strain energy and seismic input energy is obtained. The input energy is modified with a factor depending on damping ratio and ductility, and the energy that contributes to damage is obtained. The plastic energy is decreased with a factor to consider the reduced hysteretic behavior of RC members. Given the pre-selected failure mechanism, the modified energy balance equality is written using various approximations for modification factors of input energy and plastic energy in scientific literature. External work done by the design lateral forces distributed to story levels in accordance with Turkish Seismic Design Code is calculated considering the target plastic drift. Equating the plastic energy obtained from energy balance to external work done by the equivalent inertia forces considering, a total of 16 energy-based base shears for each frame are derived considering different combinations of modification factors. Ductility related parameters of modification factors are determined from pushover analysis. Relative input energy of multi degree of freedom (MDOF) system is approximated by using the modal-energy-decomposition approach. Energy-based design base shears are compared with those obtained from nonlinear time history (NLTH) analysis using recorded accelerograms. It is found that some of the energy-based base shears are in reasonable agreement with the mean base shear obtained from NLTH analysis.

• ETRI Journal
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• 제34권5호
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• pp.734-742
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• 2012

A novel interaction method for mobile phones using their built-in cameras is presented. By estimating the path connecting the center points of frames captured by the camera phone, objects of interest can be easily extracted and recognized. To estimate the movement of the mobile phone, corners and corresponding Speeded-Up Robust Features descriptors are used to calculate the spatial transformation parameters between the previous and current frames. These parameters are then used to recalculate the locations of the center points in the previous frame into the current frame. The experiment results obtained from real image sequences show that the proposed system is efficient, flexible, and able to provide accurate and stable results.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권4호
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• pp.1024-1040
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• 2014

The theoretical background and a numerical solution procedure for a time domain hydroelastic code are presented in this paper. The code combines a VOF-based free surface flow solver with a flexible body motion solver where the body linear elastic deformation is described by a modal superposition of dry mode shapes expressed in a local floating frame of reference. These mode shapes can be obtained from any finite element code. The floating frame undergoes a pseudo rigid-body motion which allows for a large rigid body translation and rotation and fully preserves the coupling with the local structural deformation. The formulation relies on the ability of the flow solver to provide the total fluid action on the body including e.g. the viscous forces, hydrostatic and hydrodynamic forces, slamming forces and the fluid damping. A numerical simulation of a flexible barge is provided and compared to experiments to show that the VOF-based flow solver has this ability and the code has the potential to predict the global hydroelastic responses accurately.

• 대한기계학회논문집
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• 제16권12호
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• pp.2298-2305
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• 1992

본 연구에서는 보의 종방향 강성치를 실제보다 훨씬 작은 횡방향 강성치 수준 으로 낮추어 시간 적분을 수행하는 대신, 종방향에 작용하는 힘을 분산시켜서 계산시 종방향 상대 변형을 억제하는 기법을 사용하였다. 또 여러개의 물체가 조인트에서 서로 연결되어 이루어진 다물체 도역학의 해는 운동 방정식과 기구학적 제한조건을 모 두 만족시켜야 하며, 상미분 방정식 해법용 시간 적분을 바로 적용할 수는 없다. 본 논문에서는 참고문헌(13)과 (14)에 소개된 반복계산법 및 계산가속기법에 의하여 Lag- range multiplier를 운동 방정식에서 소거한 후 시간 적분을 수행하는 방법을 사용한 다.

• Journal of Mechanical Science and Technology
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• 제17권1호
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• pp.77-84
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• 2003

Virtual work in multibody systems is frequently expressed as the inner product of the virtual displacement and the resultant force at the centroid. But provided that the resultant force is converted into the equipollent forces there is no restriction on where the analysis reference point is placed. There are basically three candidate points : the centroid, joint point and the instant global origin. The traditional fully recursive formulation uses the centroid, but the present work verifies that the instant global origin always shows better efficiency (e.g. 86% CPU time of the centroid for quarter car model) and joint point shows the efficiency between that of the centroid and the instant global origin. A discussion on how important it is to define the analysis reference point properly in a fully recursive formulation is also presented.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 1998년도 Proceedings of International Workshop on Advanced Image Technology
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• pp.16.2-21
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• 1998

Old movies are often corrupted by randomly located blotches and scratches. In this paper were present an efficient method for detection and removal of these distortions. The presented method is composed of two separate steps: the detection process and the restoration process. In the detection process, blotch locations are detected through global motion segmentation, the sequential approach to motion segmentation, a robust model-fit criterion and so on, we form the algorithm for the algorithm for the global motion segmentation tuned to the blotch detection problem. In the restoration process, the missing data of the detected blotch areas are temporally extrapolated from the corresponding image areas at the preceding or the succeeding image frame with considering the global motion segmentation results. We apply the presented method to moving image sequences distorted by artificial blotches. The method works very well and provides a subjective improvement of picture quality.

• 한국멀티미디어학회논문지
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• 제22권4호
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• pp.417-423
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• 2019

This paper presents an evaluation system to determine the completeness of a space map obtained by a visual SLAM(Simultaneous Localization And Mapping) algorithm. The proposed system consists of three parts. First, the proposed system detects the occurrence of loop closing to confirm that users acquired the information from all directions. Thereafter, the acquired map is divided with regular intervals and is verified whether each area has enough map points to successfully estimate users' position. Finally, to check the effectiveness of each map point, the system checks whether the map points are identifiable even at the location where there is a large distance difference from the acquisition position. Experimental results show that space maps whose completeness is proven by the proposed system has higher stability and accuracy in terms of position estimation than other maps that are not proven.

• 천문학회보
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• 제44권1호
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• pp.52.2-52.2
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• 2019

Global map of solar surface magnetic field, such as the synoptic map or daily synchronic frame, does not tell us real-time information about the far side of the Sun. A deep-learning technique based on Conditional Generative Adversarial Network (cGAN) is used to generate farside magnetograms from EUVI $304{\AA}$ of STEREO spacecrafts by training SDO spacecraft's data pairs of HMI and AIA $304{\AA}$. Farside(or backside) data of daily synchronic frames are replaced by the Ai-generated magnetograms. The new type of data is used to calculate the Potential Field Source Surface (PFSS) model. We compare the results of the global field with observations as well as those of the conventional method. We will discuss advantage and disadvantage of the new method and future works.

• 한국지구과학회지
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• 제40권3호
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• pp.283-299
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• 2019

본 연구의 목적은 국가지질공원 추진 과정에서 지역주민, 지질 전문가 및 지방자치단체 공무원 사이에서 나타나는 갈등 프레임의 양상을 규명하는 데 있다. 이를 위하여 각각 부안과 고창에서 실시된 국가지질공원 추진 관련 주민 공청회의 진행 과정을 참여자들의 사전 동의를 얻어 녹음한 후 텍스트 형태로 전사하였다. 이후 문헌연구를 통해 갈등 프레임을 분석하기 위한 기준 프레임을 개발하였으며, 이를 토대로 3명의 연구자에 의해 갈등 프레임을 분석하였다. 이렇게 분석된 갈등 프레임은 다시 언어네트워크 분석을 활용하여 지역별로 갈등 프레임 간의 구조적 특성을 분석하였으며, 그 결과는 다음과 같다. 먼저, 부안 지역에서는 'Sagree' 프레임, 'Snot' 프레임, 'Sdisagree' 프레임이 높은 위세중심성을 보였고, 언어네트워크의 중심에 위치한 'Snot' 프레임에 Cmexample 프레임, Gharm 프레임, Cmeconomy 프레임 등이 긴밀하게 연결되었다. 반면 고창에서는 'Aresource' 프레임, 'Cmexample' 프레임, 'Gharm' 프레임이 높은 위세중심성을 보였고, 언어네트워크의 중심에 위치한 'Aresource' 프레임에 'Cmexample' 프레임, 'Gharm' 프레임, 'Cmproblemsolution' 프레임 등이 긴밀하게 연결되었다. 이를 통해 부안 지역에서는 아직 이해당사자 사이의 갈등이 진행되고 있고, 고창 지역에서는 자신들의 자원을 자랑스럽게 인식하고 있음을 알 수 있었다. 그리고 부안의 이해당사자들은 갈등 해소에 있어서 경제적 이득에 초점을 둔 반면, 고창의 이해당사자들은 문제 해결에 초점을 두었다. 본 연구의 결과는 국가지질공원 추진에서 나타날 수 있는 갈등 관계를 해소하기 위한 중요한 정보를 제공했다는 점에서 의의가 있다.

• 통상정보연구
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• 제10권2호
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• pp.89-114
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• 2008

It is said that global business education in Korea must be a kind of good investment on the future of Korea, because Korea's degree of dependence upon global trade is very high. But, despite great significance of trade in economic aspect, education system on global business in Korea still remains in old paradigm focused mainly on trade in goods. The purpose of this paper is to analyse key environment of trade in Korea relating to global business education system, and to suggest some trade-friendly measures to improve the global economic environment being worse. Methodology used in this study depends on descriptive analysis by literature study. As all the paradigm of global business has shifted from 20C's trade environment to that of 21C's and still more borderless trend has progressed, it is high time Korea to design the new education system of global business to conform with the trade mode of Korea, and to execute the mode of strategic trade which is new conception of trade strategy derived from Web 2.0 trend. Major findings of this study can be summarized as follows : It is suggested that Korea should convert basic composition of trade strategy to strategic trade irrespective of company size, nationality, public or private sector, etc., and launch new instructional model considering the trade 2.0 concepts. Also, Korea's trade policies which have been based on 'trade in goods' should be changed to the frame of strategic trade so that can include various trade process such as trade in services, trade in technology, cultural contents, global investment(TRIMs), TRIPS, etc.