• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1328-1334
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• 2015

A new system for evaluating the voltage management errors of distribution equipment is presented in this paper. The main concept of the new system is to use real distribution live-line voltage to evaluate and correct the voltage measurement data from distribution equipment. This new approach is suitable for a new Distribution Management System (DMS) which has been developed for a distribution power system due to the connection of distributed generation growth. The data from distribution equipment that is installed at distribution lines must be accurate for the performance of the DMS. The proposed system is expected to provide a solution for voltage measurement accuracy assessment for the reliable and efficient operation of the DMS. An experimental study on actual distribution equipment verifies that this voltage measurement accuracy assessment system can assess and calibrate the voltage measurement data from distribution equipment installed at the distribution line.

• Journal of The Korea Institute of Healthcare Architecture
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• v.24 no.3
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• pp.17-27
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• 2018

Purpose: This study aims to examine spatial characteristics of emergency department Chronologically through case studies; and to consider the social implication of these spatial changes. Methods: In this study, a total of eight emergency departments, one for each period, were selected in order to analyze the spatial characteristics. The spatial maps of Space Syntax were employed for analyzing case studies. Results: The spatial configuration of emergency department has been changed from five or more emergency department specialties to four or less specialties such as psychiatric, pediatrics, emergency, and trauma. In the case of care initiation area, the concentrated arrangement mode was switched from the distributed arrangement mode. The spatial maps indicate that it can be seen that the tree structure changes to an annular structure emphasizing the connection between the spaces in the emergency department. This shows that the space efficiency, safe, visual control and flexibility in the planning of the emergency department are important factors affecting the spatial structure of the emergency department. Implications: In the future, it is expected that Korean emergency department will be more focused on efficiency, safe, visual control, and flexibility in the planning as in the case studies of the United States.

• Applied Microscopy
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• v.25 no.1
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• pp.111-121
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• 1995

The ultrastructure of spermatozoa in Hynobius leechii was examined with transmission electron microscope and compared with those of other urodeles and anurans. The perforatorium and the tail show most of the common feature of urodeles. However, there were several ultrastructural characteristics in an acrosome, nucleus, neck, axial rod and mitochondria related to the nucleus. The acrosome was trifoliate in transverse sections and the perforatorium consisted of two different concentric parts with a fine sharp point in a subacrosomal lumen. The nucleus consisted of two different regions of chromatin area and nuclear ridge. The nuclear ridge was composed of several bundles of five to ten minute tubular subunits of 19 nm diameter in this species, while in higher urodeles it was well developed in multi layers. The protoplasmic bead was separated by a cytoplasmic canal except the connection with only the distal portion of the nucleus. The neck was a short cylinder and contained pericentriolar material with transverse striations. In Hynobius the ring was not elongated to the tail and the mitochondria were distributed only in the protoplasmic bead around the nucleus as in Cryptobranchus, while in higher groups of urodeles it elongates to the length of the middle piece and the mitochondria follow the ring. The ring elongation may be related to the distribution of mitochondria. Hynobiidae and Cryptobranchidae are closely related based on structure of neck, the axial rod and location of mitochondria, although they are different in the composition of the axial rod.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.12
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• pp.2689-2694
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• 2012

In recent years, cyber crimes were intended to get financial benefits through malicious attempts such as DDoS attacks, stealing financial information and spam. Botnets, a network composed of large pool of infected hosts, lead such malicious attacks. The botnets have adopted several evasion techniques and variations. Therefore, it is difficult to detect and eliminate them. Current botnet solutions use a signature based detection mechanism. Furthermore, the solutions cannot cover broad areas enough to detect world-wide botnets. In this paper, we propose IRC (Internet Relay Chat) that is used to control the botnet communication in a session channel of IRC servers connected through the analysis of the relationship of the channel and the connection with the server bot-infected hosts and how to detect.

• Journal of the Korean Society of Clothing and Textiles
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• v.31 no.8
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• pp.1168-1179
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• 2007

The objective of this research is to validate the BRQ(Brand Relationship Quality) Construct perceived by fashion product consumers. In order to establish and verify the BRQ scale, qualitative survey and quantitative survey were conducted together. 1592 copies of questionnaire were distributed to women in their 20s to 40s living in Seoul and other metropolitan areas from Dec. 26, 2005 to Jan. 8, 2006, and 723 copies of them were used for statistical data. Samplel(n=482)was used for empirical analysis, and sample2(n=241) was used for cross validity test. The data was analyzed using Exploratory Factor Analysis, Confirmatory Factor Analysis, and Pearson's Correlation Analysis. BRQ emerged from exploratory factor analysis as the hierarchical construct composed of six facets including 'self-connective attachment', 'symbol/mystery', 'trust', 'nostalgia', 'intimacy', and 'knowledge'. As the fit of this structural model was not good as a result of Confirmatory Factor Analysis, it was revised to have better fitting. Finally, empirical survey results indicate the hierarchical construct consisting of eight distinct BRQ facets including 'love/commitment', 'self-connection', 'symbol', 'mystery', 'trust', 'nostalgia', 'intimacy', and 'knowledge' as best representing the final 39item BRQ Scale. Reliability, construct validity, and cross validity of the construct were verified.

• Korean Journal of Materials Research
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• v.16 no.7
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• pp.430-434
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• 2006

Au/Ni coatings are widely used in the electrical interconnect system, such as connectors, sockets and wire crimps. But due to repeated mechanical contacts, fretting corrosion occurs and causes a rapid increase in resistance. As an attempt to resolve these problem, application of Ni-P-PTFE to replace Ni undercoats was proposed, for which basic materials properties of Ni-P-PTFE coatings for preventing fretting corrosion was examined in this study. The Ni-P-PTFE coatings were formed by electroless Ni plating and PTFE coating followed by the heat-treatment. PTFE particles were found to be uniformly distributed in the Ni-P matrix. The Ni-P-PTFE coatings showed the excellent anti-adherent property with the contact angle of $104.3^{\circ}$, microhardness of 144.3 Hv comparable to that of Ni-P, and electric conductivity equivalent to that of Ni-P.

• Journal of Power Electronics
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• v.16 no.6
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• pp.2272-2283
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• 2016

This paper proposes a power conditioning system (PCS) for distributed photovoltaic (PV) applications using an asymmetric cascaded multilevel inverter with a single PV source. One of the main disadvantages of the cascaded multilevel inverters in PV systems is the requirement of multiple isolated DC sources. Using multiple PV strings leads to a compromise in either the voltage balance of individual H-bridge cells or the maximum power point tracking (MPPT) operation due to localized variations in atmospheric conditions. The proposed PCS uses a single PV source with a flyback DC-DC converter to facilitate a reduction of the required DC sources and to maintain the voltage balance during MPPT operation. The flyback converter is used to provide input for low-voltage H-bridge cells which processes only 20% of the total power. This helps to minimize the losses occurring in the proposed PCS. Furthermore, transient analyses and controller design for the proposed PCS in both the stand-alone mode and the grid-connection mode are presented. The feasibility of the proposed PCS and its control scheme have been tested using a 1kW hardware prototype and the obtained results are presented.

• Journal of the Korean Operations Research and Management Science Society
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• v.28 no.2
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• pp.75-89
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• 2003

Media Access Control (MAC) Protocol in IEEE 802.11 Wireless LAN standard supports two types of services, synchronous and asynchronous. Synchronous real-time traffic is served by Point Coordination Function (PCF) that implements polling access method. Asynchronous nonreal-time traffic is provided by Distributed Coordination Function (DCF) based on Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol. Since real-time traffic is sensitive to delay, and nonreal-time traffic to error and throughput, proper traffic scheduling algorithm needs to be designed. But it is known that the standard IEEE 802.11 scheme is insufficient to serve real-time traffic. In this paper, real-time traffic scheduling and admission control algorithm is proposed. To satisfy the deadline violation probability of the real time traffic the downlink traffic is scheduled before the uplink by Earliest Due Date (EDD) rule. Admission of real-time connection is controlled to satisfy the minimum throughput of nonreal-time traffic which is estimated by exponential smoothing. Simulation is performed to have proper system capacity that satisfies the Quality of Service (QoS) requirement. Tradeoff between real-time and nonreal-time stations is demonstrated. The admission control and the EDD with downlink-first scheduling are illustrated to be effective for the real-time traffic in the wireless LAN.

• The Transactions of the Korea Information Processing Society
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• v.2 no.3
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• pp.277-287
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• 1995

For multipoint video conference of using multimedia communication terminals, terminals are logically connected each other, and there are centralized method and distributed method in connection between terminals. Multipoint control unit is needed for the centralized method, there are two methods for implementaion such as digital method and analog method. For a meaning and implementation method of multipoint control init, main funtions of multipoint control unit are summarized and the various implementation methods are proposed in this paper.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.4 no.3
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• pp.327-336
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• 2004

In distributed autonomous mobile robot system, each robot (predator or prey) must behave by itself according to its states and environments, and if necessary, must cooperate with other robots in order to carry out a given task. Therefore it is essential that each robot have both learning and evolution ability to adapt to dynamic environment. This paper proposes a pursuing system utilizing the artificial life concept where virtual robots emulate social behaviors of animals and insects and realize their group behaviors. Each robot contains sensors to perceive other robots in several directions and decides its behavior based on the information obtained by the sensors. In this paper, a neural network is used for behavior decision controller. The input of the neural network is decided by the existence of other robots and the distance to the other robots. The output determines the directions in which the robot moves. The connection weight values of this neural network are encoded as genes, and the fitness individuals are determined using a genetic algorithm. Here, the fitness values imply how much group behaviors fit adequately to the goal and can express group behaviors. The validity of the system is verified through simulation. Besides, in this paper, we could have observed the robots' emergent behaviors during simulation.