• Journal of Advanced Navigation Technology
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• v.15 no.1
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• pp.54-60
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• 2011

The development of wireless sensor networks (WSN) can be motivated by several types of applications. However, these applications demand an energy-efficient WSN that can prolong the network lifetime and can provide high throughput, low latency and delay. Designing wireless sensor networks with the capability of prolonging network lifetime catch the attention of many researchers in wireless system and network field. Contrasts with Mobile Ad Hoc Network system, Wireless Sensor Networks designs focused more on survivability of each node in the network instead of maximizing data throughput or minimizing end-to-end delay. In this paper, we will study part of data link layer in Open Systems Interconnection (OSI) model, called medium access control (MAC) layer. Since the MAC development of energy aware MAC Protocol for wireless sensor layer controls the physical radio part, it has a large impact on the overall energy consumption and the lifetime of a node. This paper proposes a analytical approach that tries to reduce idle energy consumption, and shows the increasement of network end-to-end arrival rate due to efficiency in energy consumption from time slot management.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.45 no.2
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• pp.173-179
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• 2012

The common squid $Todarodes$ $pacificus$ is a dominant species in Korean waters, where it is captured preponderantly by the angling fishery. The spawning and nursery grounds of $T.$ $pacificus$ extend from the southern East Sea to the northern East China Sea. Consequently, the environmental conditions in this area during the spawning and nursery seasons might affect the abundance of $T.$ $pacificus$. This study, analyzed the relationship between the distribution of zooplankton and the abundance of $T.$ $pacificus$ and variation in the squid angling fishing grounds in Korean waters. There was a positive relationship between the fluctuations in zooplankton and the catch per unit effort (CPUE; $kg{\cdot}day^{-1}{\cdot}person^{-1}$) of the angling fishery in the East Sea of Korea. The main fishing season is from July to December and the CPUE was closely related to the zooplankton biomass in April in the East Sea. Recently, the center of the squid jigging ground has moved drastically from the area around Ulleung Island to the northern East Sea. We postulate that the fishing grounds of the squid angling fishery will move farther north with climate change.

• The KIPS Transactions:PartD
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• v.12D no.3 s.99
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• pp.335-344
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• 2005

Recently open data mining methods focusing on a data stream that is a massive unbounded sequence of data elements continuously generated at a rapid rate are proposed actively. Knowledge embedded in a data stream is likely to be changed over time. Therefore, identifying the recent change of the knowledge quickly can provide valuable information for the analysis of the data stream. This paper proposes a sliding window technique for finding recently frequent itemsets, which is applied efficiently in open data mining. In the proposed technique, its memory usage is kept in a small space by delayed-insertion and pruning operations, and its mining result can be found in a short time since the data elements within its target range are not traversed repeatedly. Moreover, the proposed technique focused in the recent data elements, so that it can catch out the recent change of the data stream.

• Journal of the Korean earth science society
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• v.32 no.6
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• pp.560-574
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• 2011

Satellite images that have been obtained periodically and continuously are very effective data to monitor the changes of Earth's surface. Traditionally, the studies on change detection using satellite images have mainly focused on comparison between two results after analyzing two images respectively. However, the interests in researches to catch smooth trends and short duration events from continual multi-temporal images have been increased recently. In this study, we introduce and test an approach based on 3D wavelet transform to analyze the multi-temporal satellite images. 3D wavelet transform can reduce the dimensions of data conserving main trends. Also, it is possible to extract important patterns and to analyze spatial and temporal relations with neighboring pixels using 3D wavelet transform. As a result, 3D wavelet transform is useful to capture the long term trends and short-term events rapidly. In addition, we can expect to get new information through sub-bands of 3D wavelet transform which provide different information by decomposed direction.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.6
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• pp.742-747
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• 2005

As the complexity of Web applications have increased significantly, the approach using frameworks such as Cocoon, Struts, JSF, is being suggested to develop Web applications more Quickly and efficiently. However, it Is difficult for beginners to write Apache Cocoon Sitemap files in XML. We implement a Cocoon Sitemap editor on the Java Servlet engine that allows beginners to write Cocoon Sitemap files more easily. Our system consists of three parts: Sitemap Main editor, Pipeline Viewer, and Sitemap Tracer. Sitemap Main editor support users to write BML configuration documents, so-called Sitemap file, that defines all the components pipelines, generators, and other configuration information for a Cocoon application. pipeline Viewer support users to catch the structure of Cocoon component pipelines by the medium of graphical interface. Sitemap Tracer have features to monitor of SAX events through Cocoon pipelines in a Sitemap file.

• Journal of Navigation and Port Research
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• v.28 no.3
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• pp.185-191
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• 2004

The mean and Clustering are important methods of data mining, which is now widely applied to various multi-attributes problem However, feature weighting and feature selection are important in those methods bemuse features may differ in importance and such differences need to be considered in data mining with various multiful-attributes problem. In addition, in the event of arithmetic mean, which is inadequate to figure out the most fitted result for structure of evaluation with attributes that there are weighted and ranked. Moreover, it is hard to catch hold of a specific character for assume the form of user's group. In this paper. we propose a dispersion mean algorithm for evaluation of similarity measure based on the geometrical figure. In addition, it is applied to mean classified by user's group. One of the key issues to be considered in evaluation of the similarity measure is how to achieve objectiveness that it is not change over an item ranking in evaluation process.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.5 no.1
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• pp.11-16
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• 1972

During the period from 1966 to 1968, total catches of Spanish mackerel averaged 6,000 to 7,000M/T per annual in Korea, and approximately 70 per cent of this amount was captured by drift nets. In an effort to improve the efficiency of drift nets, some experiments were conducted in 1969 to investigate the selectivity of material and mesh sizes. Seven different mesh sizes (80,85,95,100,105,110 and 115 mm) of both multi- and mono-filament netting were used, and the following results were obtained : 1, The body weight of Spanish mackerel taken with the seven different mesh sizes ranges from 0.5kg to 2.9kg, and the mode of body weight consists of three groups, 1kg ($21%$), 1.3kg($15\%$) and 1.5kg($19\%$). 2. For multi-filament net, 80 to 105mm mesh sizes were suitable to catch those three groups, and a little smalter than these for mono-filament net. 3. For Spanish mackerel only, the mono-filament material proved to have 1.5 times better selectivity than multi-filament : however, the latter proved superior for miscellaneous fish species due to its different size and shape. 4. Multi-filament net showed better selectivity for smaller species than mono-filament. (and mono-filament in general indicated opposite phenomenon.)

• Journal of Auto-vehicle Safety Association
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• v.9 no.4
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• pp.26-31
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• 2017

The current autonomous vehicle competitions are dominated by a few leading research institutions and universities. Since the leading research groups have been able to accumulate their knowledge and to develop their own algorithms for autonomous vehicle for many years, the technology gap seems too big for other followers to catch up with. On the other hand, recent researches predict that there would be a sharp rise in demand for engineers with background in autonomous vehicle technology. Therefore, it would be warranted to further expand the base of the academia and autonomous vehicle industry. In an effort to achieve this goal, it would be beneficial to hold a new format of autonomous vehicle competition event where undergraduate students can play a leading role. So, this study is to analyze the current autonomous vehicle competitions and thus to establish a strategic plan to develop a unique and improved competition event. This study investigates the pros and cons of the domestic and international autonomous vehicle competitions. Based on the analysis for the current autonomous vehicle competitions, the authors suggest a strategic plan to initiate an autonomous vehicle competition. To implement the aforementioned strategic plan, it is necessary to develop a systematic environment where the education and communication are actively available. Through the strategic plan the authors propose, the newly launching autonomous vehicle competition will able to encourage the undergraduate students and professors to dive in the cutting-edge technology thereby increasing technology competitiveness.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.739-744
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• 2010

As recent traffic policy focuses on reduction of congestion and environmental contamination, with a catch phrase, 'Green Traffic', Low Carbon Green Growth' and 'Sustainable Development', introducing the new eco-friendly transport means including railway has been emerging as critical issue. Included in the new transport means are BRT, Bimodal Tram and LRT, and this study was intended to evaluate and analyze Bimodal, among others, which generates less emission, noise and vibration thanks to hybrid type traction system employed by Bimodal Tram, which is considered a future-oriented system because of eco-friendly features and cost efficiency as well as punctuality and convenient accessibility to bus. Thus in this study, appropriateness of Bimodal Tram comparing to other system(BRT) was suggested, using conversion traffic from the road, traffic speed and CO2 emission at the metropolitan area and large provincial areas as the barometer in evaluation, and furthermore, the measures applicable to introduction strategy that will meet various functional aspects in urban area in the coming days were developed.

• Journal of Power System Engineering
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• v.21 no.2
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• pp.64-69
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• 2017

The purpose of this study is to investigate the performance characteristics of seawater cooling system for a fishing vessel. The circulation amount of refrigerant, condensation capacity, evaporation capacity, compression work and coefficient of performance(COP) were analyzed as the heat source temperature changed. The experimental setup consisted of an open-type compressor, a shell&tube type condenser, an evaporator and an expansion valve. The heat source was controlled by a constant temperature chamber. The main results of this study are summarized as follows. The condensation capacity increased with increasing heat source temperature, and it was confirmed that the effect of circulating amount of refrigerant was dominant. The amount of heat for vaporization was almost constant even though the temperature of the heat source increased. On the other hand, the compression power was increased. This is because the compression ratio increases as the condensation pressure, the enthalpy difference between inlet and outlet, the amount of circulating refrigerant increases. The performance coefficient of this system showed a tendency decreasing with increasing heat source temperature. Therefore, the basic data of the seawater cooling system for the maintenance of the catch line of the shore fishing boats was acquired through this study, and it is considered that it will be sufficient for the actual design.