• Transactions of the Korean hydrogen and new energy society
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• v.17 no.3
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• pp.338-346
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• 2006

In this paper, the test results of medium-size(120 kW class) PV system which was installed in the Taeahn thermal power station of Korea Western Power Co., Ltd., were summarized for developing the practical technology to applicate high voltage grid connection PV system. The 120 kW photovoltaic system which was consisted of 1,300 modules, PCS, and 150 kVA transformer station has been operated since Aug. 05, 2005. For verifying the modeling results of PV system, the operation data was compared with modeling results which was executed commercial PSCAD/EMTD and Psim tools. An equivalent circuit model of a solar cell has been also used for solar array modeling. A series of parameters required for array modeling have been estimated from general specification data of a solar module. A PWM voltage source inverter(VIS) and its current control scheme have been analyzed by using P&O (perturbation and Observation) MPPT algorithms technique.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.212-217
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• 2000

This first ISO/CD 7475 is a proposed revision of ISO 7475-1984, which specifies requirements for enclosures and other safety measures used to minimize mechanical hazards produced by the rotor in the measuring station of centrifugal (rotational) balancing machines. The hazards are associated with the operation of balancing machines under a variety of rotor and balancing conditions. This standard defines different classes of protection that enclosures and other protective features have to provide and describes the limits of applicability for each class of protection. At the meeting held at AFNOR in Paris in June 1999, ISO/TC 108/SC1/WG 12 agreed to prepare a first ISO Committee Draft (CD) and circulate to the member bodies for vote and comment by 3 March 2000 since publication as an International Standard requires approval by at least 75% of the member bodies casting a vote. The results of the ballot on this first ISO/CD 7475 was positive so that it will be prepared as an ISO/DIS (ISO/DIS 7475) and discussed in a meeting of ISO/TC 108/SC1 at BSI, London, u.K. in March 2000. Contents of this ISO/CD 7475 with some member comments accounted is briefly described in what follows.

• The Korean Journal of Emergency Medical Services
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• v.22 no.1
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• pp.35-47
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• 2018

Purpose: The purpose of this study was to investigate both the occurrence status of emergency vehicles traffic accidents and contents of the experiences of emergency medical technicians (EMTs) in fire station. Methods: A self-reported questionnaire was completed by 451 EMTs in fire stations in 6 cities provinces from February 9, 2017 to February 27, 2017. Results: Of 451 EMTs, 207 (45.9%) had traffic accidents experience. Regarding environment-related features, results indicated hour (12~18 hours), place (national highway), traffic flow (smooth), weather (clear), season (winter), and day (Friday). Regarding correlation analysis of differences in the number of ambulance traffic accidents pursuant to general features of accident-experienced drivers as a human factor, there were no significant differences in recruitment, driving careers of regular cars, driving careers of fire engines, and class but there were significant differences in fire-fighting careers. Accident experience in the group with careers over 6 years and less than 10 years higher than in the other groups. Conclusion: Efforts to expand fire engine driving education programs for the prevention of traffic accidents involving 119 emergency vehicles are required.

• Journal of Astronomy and Space Sciences
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• v.36 no.3
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• pp.213-223
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• 2019

This paper analyzes delta-Vs to maintain an extremely low altitude on the Moon and investigates the possibilities of performing a CubeSat mission. To formulate the station-keeping (SK) problem at an extremely low altitude, current work has utilized real-flight performance proven software, the Systems Tool Kit Astrogator by Analytical Graphics Inc. With a high-fidelity force model, properties of SK maneuver delta-Vs to maintain an extremely low altitude are successfully derived with respect to different sets of reference orbits; of different altitudes as well as deadband limits. The effect of the degree and order selection of lunar gravitational harmonics on the overall SK maneuver strategy is also analyzed. Based on the derived SK maneuver delta-V costs, the possibilities of performing a CubeSat mission are analyzed with the expected mission lifetime by applying the current flight-proven miniaturized propulsion system performances. Moreover, the lunar surface coverage as well as the orbital characteristics of a candidate reference orbit are discussed. As a result, it is concluded that an approximately 15-kg class CubeSat could maintain an orbit (30-50 km reference altitude having ${\pm}10km$ deadband limits) around the Moon for 1-6 months and provide almost full coverage of the lunar surface.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.4
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• pp.297-305
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• 2014

In this study, we installed the Automatic Identification System (AIS) receiver on the Ieodo Ocean Research Station (IORS) from November 21 to 30, 2013 in order to monitor marine traffic and fishery activity in the jurisdictional sea area. The collected AIS raw data consist of static data report (MMSI, IMO NO., Call Sign, Ship Name, etc.) and position information report (position, speed, course, etc.), and the developed program was applied to classify ships according to ship flag and type information. The nationalities are released from the first three-digit numbers (MID) of MMSI, but in general most of small ships do not send an exact ship flag through Class B type AIS, a simplified and low-power equipment. From AIS data with flag information, ships under the flag of China had the highest frequency and the second was Korean flag, while in ship type cargo and fishing vessels were dominant in sequence. As for the ships without flag information, we compared the tracks with others in order to estimate ship flags. It can be said that fleets of ships with Chinese frequently appear sail together for fisheries over the waters, because the unknown ships followed a similar moving pattern with Chinese fishing vessels.

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.2
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• pp.421-429
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• 2014

We investigated the feeding ecology of juvenile chum salmon (Oncorhynchus keta) during the critical early life stage prey selectivity of juvenile chum salmon during early marine migration in Korean waters at spring 2011. Salmon juveniles and zooplanktons were collected to draw with $20m{\times}5m$ gill net and $300{\mu}m$ mesh zooplankton net at each station on 11th-13th April n 2011. Collected zooplanktons were classified to 5 Phylum, 6 Class, 9 Order 17 Species in this study. Almost 76.4-100% species were classified to Phylum Arthropoda, dominant species was a species out of Hyperia galba of Order Amphipoda, Acartia spp and Paracalanus parvus of Order Calanoida. Collected salmon juveniles were grew up to average 4.7-5.4 cm fork length and average 1.0-1.5 g wet weight in whole station. Fish stomach content (mg/salmon) was heaver to 97.4, 82.4 and 63.2 mg wet weight/salmon in ST 2, 3, 4 than 20.4, 18.9 mg/salmon of ST 1, 5, because there are fish (sand eel, Hypoptychus dybowskii) and Krill (Euphausia) as prey in salmon stomach in ST 2, 3, 4. And ST 2, 3, 4 and 5 were dominated by Amphipoda as Hyperia galba, Themisto japonica and Gammarus sp., but ST 1 was dominated by copepod, because of absence of Amphipoda in the station. Therefore small Amphipoda as Hyperia galba was good prey for just released salmon juvenile in nature.

• Journal of the Korean Association of Geographic Information Studies
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• v.4 no.1
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• pp.57-66
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• 2001

This study used four theoretical models, such as two-point linear model, linear regression model, quadratic regression model and cubic regression model which are presented from The Ministry of Science and Technology, for extraction of urban surface temperature from Landsat TM band 6 image. Through correlation and regression analysis between result of four models and AWS(automatic weather station) observation data, this study could verify spatial distribution characteristic of urban surface temperature using GIS spatial analysis method. The result of analysis for surface temperature by landcover showed that the urban and the barren land belonged to the highest surface temperature class. And there was also -0.85 correlation in the result of correlation analysis between surface temperature and NDVI. In this result, the meteorological environmental characteristics wuld be regarded as one of the important factor in urban planning.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.3
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• pp.310-317
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• 1993

This paper presents a mechanism for improving performance of the IEEE 802.6 MAN(Metropolitan Area Network), a dual-bus structured high-speed communication network, by a more efficient use of bandwidth. The MAN protocol is able to handle various traffic and offers better transmission speed than the conventional LAN, but the unidirectional bus structure and propagation delay of request bits results in unfairness since higher nodes use more bandwidth. As the number of stations and the distances between them are increased, the problem becomes mere serious. As a solution, this paper presents a method that every station enables to identify the used slots, and that a specified class denoted 'erasure station' has with the functions of destination release, slot reuse. As a result, it is export to improve network bandwidth values of each station and the throughput and delay time was analytically analyzed, and it is shown that according to computer simulation results, this mechanism improves the network performance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.6
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• pp.1087-1094
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• 2008

Recently, XML has been widely used as a standard for a data exchange, and there has emerged the tendency that the size of XML document becomes larger. The data transfer can cause problems due to the increase in traffic, especially when a massive data such as Data Warehouse is being collected and analyzed. Therefore, an XMDR wrapper can solve this problem since it analyzes the tree structures of XML Schema, regenerates XML Schema using the analyzed tree structures, and sends it to each station with an XMDR Query. XML documents which are returned as an outcome encode XML tags according to XML Schema, and send standardized messages. As the formalized XML documents decrease network traffic and comprise XML class information, they are efficient for extraction, conversion, and alignment of data. In addition, they are efficient for the conversion process through XSLT, too, as they have standardized forms. In this paper we profuse a method in which XML Schema and XMDR_Query sent to each station are generated through XMDR(extended Meta-Data Registry) and the generation of products and XML conversion occur in each station wrapper.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.12A
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• pp.1298-1308
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• 2004

CAC (Call Admission Control) schemes for different service class are studied in many Papers. A novel priority CAC algorithm, which gives priority to a same class call according to the total resource requirements is proposed and analyzed in this paper. The proposed algorithm provides a priority according to the total resource requirements other than only in a base station. If there are efficient residual resources in the system, it will accept all new calls. Otherwise, it will selectively accept these new calls according to the total resource requirements. The results show that the proposed algorithm provides better call blocking probability, outage probability and throughput than the conventional algorithm.