• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2011년도 하계학술대회
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• pp.310-313
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• 2011

Broadcasting nature of wireless communications makes it possible to apply opportunistic network coding (OPNC) by overhearing transmitted packets from a source to sink nodes. However, it is difficult to apply network coding to the topology of multiple relay and sink nodes. We propose to use relay node selection, which finds a proper node for network coding since the OPNC alone in the topology of multiple relays and sink nodes cannot guarantee network coding gain. The proposed system is a novel combination of wireless network coding and relay selection, which is a key contribution of this paper. In this paper, with the consideration of channel state and potential network coding gain, we propose relay node selection techniques, and show performance gain over the conventional OPNC and a channel-based selection algorithm in terms of average system throughput.

• 산업경영시스템학회지
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• 제22권51호
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• pp.189-197
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• 1999

Assembly line balancing problem is known as one of difficult combinatorial optimization problems. This problem has been solved with linear programming, dynamic programming approaches. but unfortunately these approaches do not lead to efficient algorithms. Recently, genetic algorithm has been recognized as an efficient procedure for solving hard combinatorial optimization problems, but has a defect that requires long-run time and computational complexties to find the solution. For this reason, we adapt a new method called the Critical Node Method that is intuitive, easy to understand, simple for implementation. Fuzzy set theory is frequently used to represent uncertainty of information. In this paper, to treat the data of real world problems we use a fuzzy number to represent the duration and Critical Node Method based heuristic procedure is developed for solving fuzzy assembly line balancing problem.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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• pp.487-494
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• 2003

Recently it is used seismic analysis like single mode spectrum analysis, multi mode spectrum analysis and time history analysis in Korea. Because bridges are not special form of them but regular and simple form of them in our country, we must develope seismic analysis program of bridge based on single nude spectrum analysis. The program developed by this study reduces a Quantity and a time of calculation compared to SAP90 and gives accurate answers without errors. In the case of commercial program if we look for seismic load(P/sub e/(x)), we must increase the number of node and the larger the number of node the more a quantity and a time of calculation. But this program is exactly solved with basic node compared to commercial program.

• Structural Engineering and Mechanics
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• 제51권5호
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• pp.773-792
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• 2014

In this paper, we study the inverse mode shape problem for an Euler-Bernoulli beam, using an analytical approach. The mass and stiffness variations are determined for a beam, having various boundary conditions, which has a prescribed polynomial second mode shape with an internal node. It is found that physically feasible rectangular cross-section beams which satisfy the inverse problem exist for a variety of boundary conditions. The effect of the location of the internal node on the mass and stiffness variations and on the deflection of the beam is studied. The derived functions are used to verify the p-version finite element code, for the cantilever boundary condition. The paper also presents the bounds on the location of the internal node, for a valid mass and stiffness variation, for any given boundary condition. The derived property variations, corresponding to a given mode shape and boundary condition, also provides a simple closed-form solution for a class of non-uniform Euler-Bernoulli beams. These closed-form solutions can also be used to check optimization algorithms proposed for modal tailoring.

• 한국통신학회논문지
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• 제31권12C호
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• pp.1129-1134
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• 2006

In this paper, we analyze the cycle structure of punctured finite-length RA-type LDPC codes and design interleavers which have good memory efficiency and avoid short cycles. Furthermore, we introduce the check-node merging scheme for punctured finite-length RA-type LDPC codes and design simple interleavers. Simulation results show that punctured finite-length RA-type LDPC codes using the proposed simple interleavers have better performance than those with random and S-random interleavers.

• 한국정보통신학회논문지
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• 제20권5호
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• pp.1020-1030
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• 2016

본 논문에서는 이동 속성 정보를 활용하여 이동 노드간의 연결 가능성을 분석하고 마스킹 기법을 이용하여 이웃한 이동노드 중 목적 노드와 연결 가능성이 가장 높은 이동노드를 중계노드로 선정하는 EPCM(Enhanced Prediction-based Context-awareness Matrix)을 제안한다. 기존 Delay Tolerant Network (DTN)의 전송방식은 노드의 단순 이동성에 의존하여 목적노드로 메시지를 전송하게 된다. 이러한 경우 목적노드와의 연결성이 낮은 이동노드를 중계노드로 선정하게 되면 이동노드의 메시지 저장 및 처리 능력 제한으로 인하여 전송 지연 또는 패킷 손실의 원인이 된다. 본 논문의 제안된 알고리즘에서는 이동노드의 속도와 방향 속성 정보를 고려하여 목적노드와의 연결성을 계산하고 마스킹 연산을 활용하여 가장 높은 연결 가능성을 가지고 있는 중계노드를 선정하여 목적 노드까지 메시지를 전달하게 된다. 모의실험에서 Epidemic 및 PROPHET 알고리즘과 제안하는 알고리즘의 패킷 전송률을 비교한 결과 제안하는 알고리즘이 노드의 이동 속성을 고려한 연결성으로 보다 높은 패킷 전송률을 보여주었다.

• Journal of Electrical Engineering and Technology
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• 제11권1호
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• pp.65-75
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• 2016

Aiming at analyzing the power flow of the distribution systems with distribution transformer (DT) branches and PV nodes, a hybrid three-phase power flow methodology is presented in this paper. The incidence formulas among node voltages, loop currents and node current injections have been developed based on node-branch incidence matrix of the distribution network. The method can solve the power flow directly and has higher efficiency. Moreover, the paper provides a modified method to model DT branches by considering winding connections, phase shifting and off-nominal tap ratio, and then DT branches could be seen like one transmission line with the proposed power flow method. To deal with the PV nodes, an improved approach to calculate reactive power increment at each PV node was deduced based on the assumption that the positive-sequence voltage magnitude of PV node is fixed at a given value. Then during calculating the power flow at each iteration, it only needs to update current injection at each PV node with the proposed algorithm. The process is very simple and clear. The results of IEEE 4 nodes and the modified IEEE 34 nodes test feeders verified the correctness and efficiency of the proposed hybrid power flow algorithm.

• 한국유체기계학회 논문집
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• 제15권3호
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• pp.12-18
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• 2012

The Lattice Boltzmann Method has developed for solving the Boltzmann equation in Cartesian domains containing immersed boundaries of arbitrary geometrical complexity moving with prescribed kinematics. When a immersed boundaries are sweeping the fixed fluid node, refilling the node information in a vicinity of fluid nodes is one of the important issues in Lattice Boltzmann Method. In this study, we propose a simple refill algorithm for the particle distribution function based on a proper velocity, density and strain rate to enhance accuracy and stability of the method. The refill scheme based on a asymptotic analysis of LBGK model has improved accuracy than interpolation schemes. The proposed scheme in this study is validated by the simulations of an impulsively started rotating circular cylinder to investigate adaptability for fluid-structure interaction (FSI) problem. This refill scheme has improved stability and accuracy especially at high Reynolds number region.

• 한국전자통신학회논문지
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• 제10권10호
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• pp.1139-1144
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• 2015

인터넷이 가능한 기기를 상호 연결하여 새로운 정보와 서비스를 생산할 수 있는 사물인터넷은 가정, 사무실, 공장 등 다양한 분야에서 활용이 가능하다. 특히 가정에서는 하나의 작은 인터넷을 구성하고 기기들끼리 상호 연동하여 안전, 보안, 편리성, 에너지 절약 등의 효과를 얻을 수 있다. 본 연구에서는 저가이지만 강력한 기능을 제공하는 라즈베리파이에 각종 센서를 연결하여 가정의 환경을 모니터링하고 제어할 수 있는 스마트홈 프로토타입을 구현하였다. 구현된 시스템은 단순히 센서로서 역할 뿐만 아니라 외부의 네트워크에서 직접 접속할 수 있는 웹 노드로서의 역할을 수행한다. 따라서 별도의 서버가 필요 없으므로 경제적이며 다수의 웹 노드들이 상호 연동할 수 있어 확장성과 융통성을 제공할 수 있다.

• Journal of Plant Biotechnology
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• 제8권1호
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• pp.37-41
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• 2006

In vitro mass multiplication of Vanilla planifolia was investigated using node as explant. Multiple shoots were developed in MS medium supplemented with $2.0mgl^{-1}$ 6-benzylaminopurine and $1.0mgl^{-1}$ $\alpha$-naphthalene acetic acid. Multiple shoots were maintained for 6-T weeks with regular subculturing at the end of $3^{rd}$ week onto fresh medium. The maximum number of shoots at the rate of 12.8 per node segment was achieved over a period of four weeks. The elongated shoots were separated from the shoot clusters and were transferred onto half strength MS medium supplemented with indole-3-acetic acid ($1.0mgl^{-1}$) over a period of 28 days for induction of roots. The development of roots was observed on $7^{th}$ day of incubation. The in vitro raised plantlets were transferred to poly-cups, covered with polyethylene sheets and maintained under shade net for 25 days for hardening. Finally these plants were transferred to field and recorded that 85 % of tissue cultured plants were survived. From the present study, a simple and efficient micropropagation protocol was developed for Vanilla planifolia using single node segments as explants.