• 한국정보통신학회논문지
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• 제16권1호
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• pp.81-97
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• 2012

본 논문의 목적은 인터도메인 라우팅 프로토콜인 BGP의 '최근동향'을 조사하는 것이다. 먼저 BGP를 BGP 정책과 의사 결정 과정 중심으로 살펴보았다. 그리고 인터도메인 라우팅의 'open question(공개된 문제점)'으로 남아 있는 문제들을 1) 프로토콜의 안정성, 2) 트래픽 엔지니어링, 3) QoS(Quality of Service) 관점에서 조사하고, 왜 이 문제들이 현재 해결하기 어려운지를 살펴보았다. 또 이 문제들을 해결하기 위한 BGP 분야의 가장 최근 연구 동향을 조사하였다.

• 한국초등수학교육학회지
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• 제1권1호
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• pp.17-32
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• 1997

오늘날 우리나라에서는 열린 교육이 이론과 실제의 양면에서 연구되고 실천되어 오고 있다. 본고에서는 초등학교 수학 교육에서 실용적으로 사용될 수 있는 열린 교육의 학습 지도 방법 세 가지를 소개하였는데, 이들은 ‘오픈 엔드 어프로치,’ ‘문제에서 문제로,’ 그리고 ‘문제 설정’이다. 이들 세 가지 학습 지도 방법 각각에 대하여 그 의미를 분석하고, 구체적인 지도 계획을 제시한 다음, 학생들의 실제 활동의 예를 보였다.

• 천문학회보
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• 제40권2호
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• pp.28.1-28.1
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• 2015

Open clusters are one of stellar systems consisting of a few hundreds to thousands of stars. The cluster members are, in general, believed to be a coeval stellar population at the same distance, and therefore they have almost the same properties in chemical composition and kinematics. Owing to these advantages, the clusters are utilized in many astronomy studies, such as the calibrations of distance and stellar age scales, assessments of stellar evolution theories, and the chemical evolution of the Galactic disk. Young open clusters are, inter alia, superb objects to study star formation process as most of stars are known to be formed in clusters. In this talk, I will review the uses of these young open clusters in star formation studies based on the ongoing work of our research group on the stellar initial mass function, an age spread problem, mass accretion rate of pre-main sequence stars, and a feedback of high-mass stars on surroundings.

• 전기학회논문지
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• 제63권9호
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• pp.1317-1320
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• 2014

In case of using three-phase induction motor in three-phase power system, if he deficiency happens in phase among three-phase, the motor will drive in an open phase state. As to the motor, the continuing operation is possible then, but the phenomenon that the power supply stops happening by the result of the overload electricity order on the healthy phase of two phases with a damage and activating the circuit breaker. Consequently, in order to overcome this problem in treatise accordingly. I propose an uninterruptible power supply which is able to prevent that the over current on the health phase through the restoration that in case happening open phase on the power line when driving the motor. Also, it is possible to supply power consecutively without interruption of electric power and we proved the performance and reliability through an experiment.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제15권2호
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• pp.115-126
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• 2011

The aim of this study was to explore teachers' values about teaching mathematics in the classrooms which implemented Lesson Study and Open Approach as a teaching approach. The targeted group was 83 school teachers from 4 schools participating in a teacher professional development project. The data was gathered through teacher questionnaires, lesson observations and interviews. Data analysis is based on Bishop's (1988; 2003; 2007) and Komin's (1990) frameworks. The results from the implementation of Lesson Study and Open Approach in Thai classroom found the different of the roles and behaviors of teachers and students in classroom. The results revealed 3 kinds of values about teaching: Mathematical values, General educational values, Mathematics educational values and also found that most of the teachers valued problem solving as an innovative teaching approach as against traditional approaches they were familiar with.

• 대한전기학회논문지:전력기술부문A
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• 제54권7호
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• pp.352-357
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• 2005

In competitive electricity markets, the System Operator (SO) coordinates the overall maintenance schedules when the collective maintenance schedule reported to 50 by Gencos not satisfy the specified operating criteria, such as system reliability or supply adequacy. This paper presented a method that divides generator maintenance scheduling of the 50 into a master-problem and a sub-problem. Master-problem is schedule coordination and sub-problem is DC-optimal power flow. If sub-problem is infeasible, we use the algorithm of modifying operating criteria of master-problem. And, the 50 should use the open information only, because the information such as cost function of a generator and bidding Price is highly crucial for the strategies of profit maximization.

• Industrial Engineering and Management Systems
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• 제15권1호
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• pp.32-40
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• 2016

This paper considers a special case of a three machine flow shop scheduling problem in which operation processing time of each job is ordered such that machine 1 has the longest processing time, whereas machine 3, the shortest processing time. The objective of the problem is the minimization of the total completion time. Although the problem is simple, its complexity is yet to be established to our best knowledge. This paper first introduces the problem and presents some optimal properties of the problem. Then, it establishes several special cases in which a polynomial-time optimal solution procedure can be found. In addition, the paper proves that the recognition version of the problem is at least binary NP-complete. The complexity of the problem has been open despite its simple structure and this paper finally establishes its complexity. Finally, a simple and intuitive heuristic is developed and the tight worst case bound on relative error of 6/5 is established.

• 디지털콘텐츠학회 논문지
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• 제19권4호
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• pp.693-700
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• 2018

네크워크 장애 발생 시 재빠른 장애조치를 지원하기 위한 방법으로 가상 라우터 이중화 프로토콜 (VRRP)이 고안되었다. VRRP는 LAN 상에서 외부로 나가는 게이트웨이 역할을 하는 가상의 라우터가 존재하고, 이를 마스터 라우터와 백업 라우터 간에 동적으로 선정함으로써 마스터 라우터의 장애 발생 시에도 사용자들이 중단 없는 망 서비스를 받을 수 있도록 네트워크 이중화 기능을 제공한다. 하지만, 라우터 장비를 운용하기 위해 필요한 네트워크 운영체제 (OS) 들은 비싼 초기 도입 비용과 판매 기업에 종속된 closed 아키텍처라는 단점을 가지고 있다. 이를 해결하고자, 오픈 소스를 기반으로 한 개방형 네트워크 소프트웨어 플랫폼인 Open N2OS가 개발 되었다. Open N2OS는 하드웨어에 종속되지 않고, 고가용성, 유연한 확장성, 다양한 네트워킹 기능을 지원하는 특징을 갖고 있다. 본 논문에서는 Open N2OS에서 지원하는 VRRP 프로토콜의 기능 동작과 구조를 다루고, Open N2OS의 명령어 인터페이스를 통해 제공되는 VRRP 관련 명령어들을 소개한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.1026-1029
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• 2002

Outlet of gas has been a big problem in deforming rubber or plastic in pressing mold. Air vent has been used to solve the problem, but it has weak points such as the increased cost, the increased number of process, and vent marks on the surface of a produce. In this study, the sintering method is used for making porous metal mold. Porous metal mold has many open pores, which are very small. When Porous metal mold is used for pressing mold, all process would be made short, produce cost would be down, and it would not leave vent marks on the surface of a produce. Porosity varies from sintering and pressing conditions, which are the pressure of compacting powder, the length of sintering time, sintering temperature and sintering atmosphere etc. This study will find optimized sintering temperature condition for the Porous metal mold.

• 한국통신학회논문지
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• 제17권3호
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• pp.225-231
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• 1992

In this paper, queuing networks with open chains are considerd to analyze the performance of packet switching networks. Networks are classified into backbone and local access networks. Networks for performance analysis are distributed to twelve regions and DNS is the backbone. Analysis was conducted using the real values from the input to existing networks and mathematical estimation values. As the result of analysis, the mean of end-to-and delay for each chain was presented. Except special regions, we found that there was a little difference between real values and mathematical estimation values. However, there could be a performance problem in total networks due to the increase of communication volumes in each region. So we proposed some solutions to this problem.