• 조명전기설비학회논문지
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• 제26권2호
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• pp.51-60
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• 2012

An improved method for detecting fault distance in overhead transmission lines is described in this paper. Based on single-ended measurement, propagation theory of traveling waves together with the wavelet transform technique is used. In estimating fault location, a simple, but fundamental method using the time difference between the two consecutive peaks of transient signals is considered; however, a new method to enhance measurement sensitivity and its accuracy is sought. The algorithm is developed based on the lattice diagram for traveling waves. Representing both the ground mode and alpha mode of traveling waves, in a lattice diagram, several relationships to enhance recognition rate or estimation accuracy for fault location can be found. For various cases with fault types, fault locations, and fault inception angles, fault resistances are examined using the proposed algorithm on a typical transmission line configuration. As a result, it is shown that the proposed system can be used effectively to detect fault distance.

• Journal of Advanced Research in Ocean Engineering
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• 제2권4호
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• pp.169-178
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• 2016

Recently, artificial reefs (ARs) have been frequently used primarily owing to the development in AR materials and projects for relatively complicated, large ARs. Among several engineering issues of ARs, wake region of an AR has been characterized because these regions have a high probability of recruiting seaweed spores, providing an energy saving zone, and facilitating deposition of sediments, nutrients, and bio-deposits. To characterize an efficiency index of an AR wake region and its dependency on the prevailing water flow directions, this study proposes a so-called efficiency index diagram. This characterization is done by normalizing the wake volumes with respect to the real AR volume and illustrating how efficiency indices vary with respect to the inlet flow directions. As a result, according to the diagram characteristics such as an averaged efficiency index, fundamental symmetric angle, secure angles, and principal directions, we can easily figure out how a target AR should be aligned along the main water flows to maximize the wake region around the AR. In addition, six ARs are considered and their efficiency index diagrams are illustrated to pinpoint the physical characteristics.

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 2002년도 제7차 학술대회 초록집
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• pp.15-29
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• 2002

MRI에서 펄스 시퀀스(pulse sequence)란 고주파 RF(radiofrequency) 펄스 및 경사자장(gradient) 펄스를 가하고 MR 신호를 획득하는 순서를 시간대별로 도식화 한 pulse diagram을 이야기한다. 이러한 pulse sequence는 실제로 영상을 획득하기 위한 RF amplifier, gradient amplifier 등의 하드웨어를 순차적(sequential)으로 구동하는 역할을 한다. 따라서 이러한 pulse sequence는 현재 임상적으로 사용되는 다양한 영상기법들을 이해하는데 필수적이다.

• 대한인간공학회지
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• 제33권2호
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• pp.77-86
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• 2014

Objective: The purpose of this study is to grasp the fundamental structure of incident occurrence in nuclear organizations based on system thinking, and analyze how various causes are interrelated in terms of the causal loop diagram. Background: The recent domestic and overseas nuclear power plant-related incidents and accidents are directly or indirectly associated with safety culture, and thus effective plans for the improvement of safety culture are being called for. While the safety of a nuclear power plant is highly dependent upon technology and equipment, the utilization, maintenance and inspection of the technology and equipment are conducted by workers of the nuclear power plant. Method: Methodology of system thinking perspective using causal loop analysis. Results: As a result of the analysis, first, it turned out that the fundamental cause of incident occurrence in nuclear organizations is time constraint. Second, if a workload of workers increases, their adherence to regulations and procedures comes to be reduced due to time constraint. Third, it is needed, through organizational learning education, to increase actions made from thoughts considering safety as the utmost priority in advance. Fourth, it is necessary to improve professionalism by enhancing educational programs for new workers, and to develop various scenarios with which they can cope with certain situations. Application: This paper provides a base for system dynamics simulation model for future study.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제27권3호
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• pp.267-281
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• 2013

본 연구는 사다리타기 게임을 중학교 수학에서 함수의 도입과 고등학교에서의 합성함수의 도입을 위한 소재로서의 가능성을 탐색하고 있다. 사다리타기 게임에 사용되는 사다리그림은 일대일대응이 되므로 집합을 도입하지 않고도 직관적으로 쉽게 함수의 개념을 도입할 수 있다. 또한 하나의 가로선을 갖는 사다리그림은 일대일대응이므로 r개의 가로선을 갖는 사다리그림은 r개의 일대일대응의 합성함수를 결정함을 알 수 있다. 본 연구에서는 일대일대응에 대한 기본적인 몇 가지 사실에 대하여 사다리그림을 이용하여 수학적으로 증명하였고, 중학교에서의 함수와 고등학교에서 합성함수를 사다리타기 게임으로 도입할 수 있음을 제시하였다. 일대일대응에 대한 사다리그림은 학생들의 흥미와 집중을 유도할 수 있을 뿐만 아니라 함수의 개념을 직관적으로 쉽게 이해하게 하는 좋은 소재로 활용할 수 있다.

• 대한수학회지
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• 제50권2호
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• pp.425-444
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• 2013

We construct some hyperbolic hyperelliptic space forms whose fundamental groups are generated by only two or three isometries. Each occurring group is obtained from a supergroup, which is an extended Coxeter group generated by plane re ections and half-turns. Then we describe covering properties and determine the isometry groups of the constructed manifolds. Furthermore, we give an explicit construction of space form of the second smallest volume nonorientable hyperbolic 3-manifold with one cusp.

• 산업경영시스템학회지
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• 제41권4호
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• pp.123-130
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• 2018

Triangulation is one of the fundamental problems in computational geometry and computer graphics community, and it has huge application areas such as 3D printing, computer-aided engineering, surface reconstruction, surface visualization, and so on. The Delaunay refinement algorithm is a well-known method to generate quality triangular meshes when point cloud and/or constrained edges are given in two- or three-dimensional space. In this paper, we propose a simple but efficient algorithm to triangulate Voronoi surfaces of Voronoi diagram of spheres in 3-dimensional Euclidean space. The proposed algorithm is based on the Ruppert's Delaunay refinement algorithm, and we modified the algorithm to be applied to the triangulation of Voronoi surfaces in two ways. First, a new method to deciding the location of a newly added vertex on the surface in 3-dimensional space is proposed. Second, a new efficient but effective way of estimating approximation error between Voronoi surface and triangulation. Because the proposed algorithm generates a triangular mesh for Voronoi surfaces with guaranteed quality, users can control the level of quality of the resulting triangulation that their application problems require. We have implemented and tested the proposed algorithm for random non-intersecting spheres, and the experimental result shows the proposed algorithm produces quality triangulations on Voronoi surfaces satisfying the quality criterion.

• 한국디지털정책학회:학술대회논문집
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• 한국디지털정책학회 2004년도 International Conference on Digital Policy & Management
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• pp.435-448
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• 2004

While Internet promises ubiquitous access, it also creates a fundamental challenge to the traditional ownership toward digital assets traded in e-commerce market. Sharing digital information freely through shared networks leads to many untapped business opportunities, but uncontrolled digital asset transaction undermines many electronic business models. Thus, in this Internet age, proper protection and safe delivery of Intellectual Property (IP) and its representation as digital assets would be a crucial ingredient of building trust in upcoming e-business environment. In this paper, we give a general structural diagram of Intellectual Property Management and Protection (IPMP) and implement an IPMP prototype based on the RSA encryption algorithm and XrML (eXtensible rights Markup Language) WORK tags to show how proper protection and safe delivery of the intellectual property is achieved. This study concludes that IPMP mechanism may contribute significantly to the volume and quality of e-commerce market.

• 한국세라믹학회지
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• 제49권2호
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• pp.142-145
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• 2012

In order to investigate the surface SHG, (110) pure STO single crystals were exposed to a reducing atmosphere to induce the reduction of the Ti ion and the release of oxygen from the lattice compensating the reduction of the Ti ions. The anisotropy and asymmetry of SHG intensity explains a slight shrinkage. The incoming fundamental wave was polarized either in the $p$-in or $s$-in to the plane of incidence for the reflection geometry. The SH polarization diagram could be described by the electric dipole and/or quadrupole contribution of reduced STO single crystal surface.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 1998년도 가을 학술발표논문집 Vol.25 No.2 (3)
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• pp.216-219
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• 1998

이 논문에서는 IMT-2000(International Moblie Telecommunication-2000)시스템에서의 멀티미디어 트래픽을 전송하기 위한 핸드오프 처리절차를 제안하였다. 이 절차에는 기본 코드채널(Fundamental Code Channel)과 부가 채널(Supplemental Code Channel)을 제어하기 위한 핸드오프관련 메시지들이 포함되었다. 부가 채널코들를 사용하기 위한 협상은 전송되는 트래픽의 크기에 따라 핸드오프 초기화 동안 수행된다. 그리고 MS(Moblie Station), BTS(Base Station transceiver Subsystem) 및 BSC(Base Station Controller)사이에서의 핸드오프 처리를 위한 호 흐름도와 상태천이도 (State Transition Diagram)도 설계하였다.