• 대한조선학회논문집
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• 제55권1호
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• pp.66-74
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• 2018

In order to evaluate the precision degree of the blocks on the dock, the shipyards recently started to use the point cloud approaches using the 3D scanners. However, they hesitate to use it due to the limited time, cost, and elaborative effects for the post-works. Although it is somewhat traditional instead, they have still used the electro-optical wave devices which have a characteristic of having less dense point set (usually 1 point per meter) around the contact section of two blocks. This paper tried to expand the usage of point sets. Our approach can estimate the rework time to weld between the Pre-Erected(PE) Block and Erected(ER) block as well as the precision of block construction. In detail, two algorithms were applied to increase the efficiency of estimation process. The first one is K-mean clustering algorithm which is used to separate only the related contact point set from others not related with welding sections. The second one is the Concave hull algorithm which also separates the inner point of the contact section used for the delayed outfitting and stiffeners section, and constructs the concave outline of contact section as the primary objects to estimate the rework time of welding. The main purpose of this paper is that the rework cost for welding is able to be obtained easily and precisely with the defective point set. The point set on the blocks' outline are challenging to get the approximated mathematical curves, owing to the lots of orthogonal parts and lack of number of point. To solve this problems we compared the Radial based function-Multi-Layer(RBF-ML) and Akima interpolation method. Collecting the proposed methods, the paper suggested the noble point matching method for minimizing the rework time of block-welding on the dock, differently the previous approach which had paid the attention of only the degree of accuracy.

• 한국전자통신학회논문지
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• 제15권2호
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• pp.313-318
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• 2020

300도 이상의 높은 용융점을 갖는 소위 엔지니어링 플라스틱은 기구적인 강성과 내화학성 및 마찰 및 마모성능이 우수하여 여러 산업에서 금속을 대체하는 소재로 각광받고 있다. 본 연구에서는 용융적층모델링 공법을 기반으로 하는 3D 프린터에서 높은 용융점을 갖는 엔지니어링 플라스틱을 조형할 수 있도록 방열특성이 우수한 3D 프린터 nozzle부의 구조를 설계하고 이를 해석적으로 검증하였다. 높은 온도로 가열되는 heat block과 필라멘트가 이송되는 nozzle상부 간의 단열 및 신속한 냉각을 위하여, 열전도계수가 낮은 열차단부(heat brake부)를 2중으로 구성하였고, 열차단부에 생성되는 열이 냉각핀을 통해 대기에 의해 냉각되는 구조를 적용하였다. 개선된 nozzle부 구조설계를 통해 종래 3D 프린터의 BCnozzle과 비교할 때, heat sink부에서의 온도를 50% 가량 낮출 수 있었으며, heat block에 직접적으로 연결된 heat brake부 최종단의 정상상태 온도를 14% 가량 낮출 수 있었다.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송∙미디어공학회 2019년도 추계학술대회
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• pp.20-21
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• 2019

The Joint Video Experts Team (JVET) has been working on the development of next generation of video coding standard called Versatile Video Coding (VVC). Position Dependent Intra Prediction Combination (PDPC) which is one of the major tools for intra prediction refines the prediction through a linear combination between the reconstructed samples and the predicted samples according to the sample position. In VVC WD6, nScale which is shift value that adjusts the weight is determined by the width and height of the current block. It may cause that PDPC is applied to regions that do not fit the characteristics of the current intra prediction mode. In this paper, we define nScale for each width and height so that the weight can be applied independently to the left and top reference samples, respectively. Experimental results show that, compared to VTM 6.0, the proposed method gives -0.01%, -0.04% and 0.01% Bjotegaard-Delta (BD)-rate performance, for Y, Cb, and Cr components, respectively, in All-Intra (AI) configuration.

• 한국멀티미디어학회논문지
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• 제12권6호
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• pp.785-793
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• 2009

This paper proposes a signature using dominant singular values for video sequence matching. By considering the input image as matrix A, a partition procedure is first performed to separate the matrix into non-overlapping sub-images of a fixed size. The SVD(Singular Value Decomposition) process decomposes matrix A into a singular value-singular vector factorization. As a result, singular values are obtained for each sub-image, then k dominant singular values which are sufficient to discriminate between different images and are robust to image size variation, are chosen and normalized as the signature for each block in an image frame for matching between the reference video clip and the query one. Experimental results show that the proposed video signature has a better performance than ordinal signature in ROC curve.

• Computers and Concrete
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• 제18권1호
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• pp.99-112
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• 2016

Since the preservation of monuments is very important to human societies, different methods are required to preserve historic structures. In this paper, 3D model of arch stone bridge at Pont Saint Martin, Aosta, Italy, was simulated by 1660 integrated separate stones using ABAQUS$^{(R)}$ software to investigate the seismic susceptibility of the bridge. The main objective of this research was to study a method of preservation of the historical stone bridge against possible earthquakes using FRP techniques. The nonlinear behavior model of materials used theory of plasticity based on Drucker-Prager yield criterion. Then, contact behavior between the block and mortar was modeled. Also, Seismosignal software was used to collect data related to 1976 Friuli Earthquake Italy, which constitutes a real seismic loading. The results show that, retrofitting of the arch stone bridge using FRP techniques decreased displacement of stones of spandrel walls, which prevents the collapse of stones.

• International Journal of Internet, Broadcasting and Communication
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• 제12권2호
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• pp.144-149
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• 2020

A database called Home Location Register(HLR) plays a major role in location management in mobile cellular networks. The objectives of this paper are to identify the problems of the current HLR system through rigorous analysis, to suggest solutions to them. The current HLR backup method is a process of simply writing the changed memory SLD block to disk, which has a problem in maintaining database consistency. Since information change and backup are performed separately by separate processes, there is a risk of information inconsistency when an error restart occurs. To solve this problem, a transaction concept was introduced for subscriber-related operation functions and a recovery method through logging and checkpointing was introduced. The subscriber related functions of tasks terminated normally by the suggested process are recovered with consistency even after system restarts. Performance is also not affected seriously because disk tasks for log occur with only subscriber related functions.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 춘계학술대회 논문집
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• pp.245-248
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• 2008

This paper gives a description of the mode'ling and control of a single phase PWM(Pulse Width Modulation) converter for HEMU-400X(High-speed Electric Multiple Unit - 400 km/h experiment). The converter is part of a Auxiliary power unit supplied by the 25[kV], 60[Hz] overhead line. A model of the converter in a synchronously rotating reference frame of coordinates is used to develop a new type of control. The control system has separate controllers for the active and reactive current, permitting the free choice of the power factor. This paper proposes a new control method of PWM converter for Auxiliary power unit.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 추계종합학술대회
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• pp.741-744
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• 2003

본 논문은 모자이크 배경을 생성하고 변화되는 정보만을 전송함으로서 동적기반 압축시스템을 제안한다. 동적 모자이크 배경은 카메라 움직임 정보를 이용하여 단일영상으로 점진적으로 통합된다. 카메라 움직임 예측을 위해 각각의 영상들과 이전영상과의 원근투영 매개변수를 순차적으로 계산하였다. 카메라 움직임은 배경영역과 전경영역에서 식별함으로서 배경상에서 강건하게 계측된다. 수정된 블록기반 움직임계측은 배경영역을 분리하는데 이용되었다.

• 대한전기학회논문지:시스템및제어부문D
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• 제52권10호
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• pp.598-605
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• 2003

In this paper, we propose the method that separates PPG signal and motion artifact signal from two input signals using new independent component analysis algorithm in time domain. In order to eliminate the large level artifact efficiently, block interleaving. lowpass time filtering and innovation processing technique were applied in ICA preprocessing, and FastICA algorithm were applicable. Experiments are made with the numerical simulation and the real PPG signal including four kinds of motion artifact pattern. Our results show that ICA can effectively detect, separate and remove motion artifact in input signals. Then from the separated signals we restore the original PPG signal and propose a new method which computes SpO$_2$ using ICA mixing matrix.

• 한국통신학회논문지
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• 제28권1C호
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• pp.37-46
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• 2003

정보보호 기술이 부분적, 폐쇄적, 개별적 개발에서 개방적, 광역적, 통합적으로 변모해 감에 따라 각각의 보안시스템을 구조적으로 통일하고 분산된 관리 방법을 일원화하기 위한 연구의 필요성이 증대되었다 그러나 아직까지는 각각의 보안시스템을 하나로 통합시켜 관리할 수 있는 공통된 프레임워크가 존재하지 않는다 따라서 이 논문에서는 각각의 보안 시스템을 체계적으로 관리하고 분산된 관리 방법을 일원화 할 수 있는 정책기반 네트워크 보안 관리 모델을 제시한다.