• Management & Information Systems Review
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• v.9
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• pp.25-39
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• 2002

We consider the Fuzzy clustering which is devised for partitioning a set of objects into a certain number of groups by assigning the membership probabilities to each object. The researches carried out in this field before show that the Fuzzy clustering concept is involved so much that for a certain set of data, the main purpose of the clustering cannot be attained as desired. Thus we propose a new objective function, named as Fuzzy-Entroppy Function in order to satisfy the main motivation of the clustering which is classifying the data clearly. Also we suggest Mean Field Annealing Algorithm as an optimization algorithm rather than the. ISODATA used traditionally in this field since the objective function is changed. We show the Mean Field Annealing Algorithm works pretty well not only for the new objective function but also for the classical Fuzzy objective function by indicating that the local minimum problem resulted from the ISODATA can be improved.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.25 no.6
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• pp.36-41
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• 2002

We consider the Fuzzy clustering which is devised for partitioning a set of objects into a certain number of groups by assigning the membership probabilities to each object. The researches carried out in this field before show that the Fuzzy clustering concept is involved so much that for a certain set of data, the main purpose of the clustering cannot be attained as desired. Thus we propose a new objective function, named as Fuzzy-Entroppy Function in order to satisfy the main motivation of the clustering which is classifying the data clearly. Also we suggest Mean Field Annealing Algorithm as an optimization algorithm rather than the ISODATA used traditionally in this field since the objective function is changed. we show the Mean Field Annealing Algorithm works pretty well not only for the new objective function but also for the classical Fuzzy objective function by indicating that the local minimum problem resulted from the ISODATA can be improved.

• Management & Information Systems Review
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• v.14
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• pp.51-65
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• 2004

We consider the Fuzzy clustering which is devised for partitioning a set of objects into a certain number of groups by assigning the membership probabilities to each object. The researches carried out in this field before show that the Fuzzy clustering concept is involved so much that for a certain set of data, the main purpose of the clustering cannot be attained as desired. Thus we Propose a new objective function, named as Fuzzy-Entroppy Function in order to satisfy the main motivation of the clustering which is classifying the data clearly. Also we suggest Mean Field Annealing Algorithm as an optimization algorithm rather than the ISODATA used traditionally in this field since the objective function is changed. We show the Mean Field Annealing Algorithm works pretty well not only for the new objective function but also for the classical Fuzzy objective function by indicating that the local minimum problem resulted from the ISODATA can be improved.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2000.11b
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• pp.9-13
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• 2000

This paper represents analysis of field test results of terrestrial DTV on channel repeaters over Taejon city area. Two kind of on channel repeaters were tested. Non-regenerative repeater performs filtering, amplifying and re-transmit received main DTV signal. Regenerative repeater performs demodulation, modulation and amplifying and re-transmit received main DTV signal. The non-regenerative repeater threshold D/U ratio is about 10dB better than regenerative repeater's one.

• 전기의세계
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• v.20 no.2
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• pp.19-26
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• 1971

To proteting hunting of synchronus motor a new one which has two field windings is designed. One is main field winding excited constantly and the other is control field winding excited only during the load of motor changes. The oscillation of the motor is controlled by increasing or decreasing the control field excitation. To determine the optimal field excitation the Pontryagin's minimum principle is applied. Also this paper gives the optimal trajectories of the motor and it's transition time. This motor has some of better properties than the old motor with damper winding. These phroperties are (1) there is no hunting (2) the transient stability is improved (3) transition time is very short.

• Journal of the Korean Society for information Management
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• v.37 no.3
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• pp.253-274
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• 2020

In this study, text mining and main path analysis (MPA) were applied to understand the origins and development paths of research areas that make up the mainstream of Korean studies. To this end, a quantitative analysis was attempted based on digital texts rather than the traditional humanities research methodology, and the main paths of Korean studies were extracted by collecting documents related to Korean studies including citation information using a citation database, and establishing a direct citation network. As a result of the main path analysis, two main path clusters (Korean ancient agricultural culture (history, culture, archeology) and Korean acquisition of English (linguistics)) were found in the key-route search for the Humanities field of Korean studies. In the field of Korean Studies Humanities and Social Sciences, four main path clusters were discovered: (1) Korea regional/spatial development, (2) Korean economic development (Economic aid/Soft power), (3) Korean industry (Political economics), and (4) population of Korea (Sex selection) & North Korean economy (Poverty, South-South cooperation).

• Journal of the Korean Society of Earth Science Education
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• v.1 no.1
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• pp.72-84
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• 2008

This study is focused on the main concepts of gravity and geomagnetics which are introduced in the earth science textbooks of high school in 7th curriculum. This study examines the validity and accuracy of the Earth Science textbooks and shows some effective teaching plans by using the latest materials. This study also illustrates the main concepts of gravity and geomagnetics through presenting some effective and practical teaching-learning methods. The results of the study were as follows: First of all, a number of main concepts of six textbooks of high school were selected; the field of gravity, the direction and dimension of gravity, the measurement of gravity, the main reason of gravity anomaly and geoid, earth terrestrial magnetic field, secular variation of goemagnetics. Secondly, most Earth Science textbooks of high school explains the main concepts of the gravity and geomagnetics in similar ways. Those textbooks, however, don't put an emphasis on the essential contents which has been regarded as important thing in terms of the current educational course of study. The high school textbooks also use the material which is too old-fashioned and has some problems of accuracy and validity. Especially, many main concepts of the textbooks and scientific data(such as the direction of gravity, the measurement of gravity, the main reason of gravity anomaly, the use of geoid, secular variation) are different with those of South Korea, In addition, some materials(graphs and diagrams) are very old ones and they don't have authentic information.Finally, Among the various main concepts, some important ideas (the direction of the gravity and the method of measuring gravity, the measurement and use of gravity anomaly, the definition of geoid and secular variation of geomagnetics) should be corrected by showing the latest and authentic materials.

• Journal of IKEEE
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• v.23 no.3
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• pp.1092-1095
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• 2019

In this paper, we propose the development of an embedded board for construction of smart factory. The proposed embedded board for construction of smart factory consists of main module, ADC module, I/O module. Main module is a main calculating device which includes communication pard that allows interface with external device with using industrial protocol and is ported operating system makes board operating into. ADC module takes part in transferring digital signal has converted from electrical signal to the main module from the external sensor which is installed on the field. I/O module is an input and output module which transfers to the main module about a status, alarm, command signal of field device and it has a function that blocks external noises from field device with isolation circuit into it. In order to evaluate the performance of the proposed embedded board for construction of smart factory, it has been tested by an authorized testing institute. As a result, quantity of interacting protocol was 5, speed of hardware clock synchronization was under 10us and operating time of battery without source power was over 8 hours. It produced the same result as the world's highest level.

• Korean Journal of Agricultural Science
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• v.31 no.2
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• pp.149-160
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• 2004

This study had carried out an analysis of leaf tobacco production cost by cost items, growing stages, and farm sizes per 10a to provide the basic data for determination of the purchasing price of leaf tobacco by KT&G. Considering the survey results of 12 tobacco farm households, the composition rates of production cost by items revealed as 7-10% for land service, 5-22% for depreciation, 13-25% for material costs, 50-65% for labour cost respectively. The production cost of leaf tobacco by growing stages were shown as 15.3% in nursery bed period, 32.3% in main growing period in field, 30.8% in harvesting period and 21.6% in packing period. The magnitude of wage expenditure was appeared as harvesting stage, packing stage, growing stage on main field and nursery bed stage in order. The amount of material costs were revealed as the growing stage in main field, harvesting stage, nursery bed stage and packing stage respectively. The production costs of leaf tobacco per 10a by farm sizes were shown as 1,615,879won for small farm, 1,446,896won for medium farm and 1,454,408won for large farm respectively. The production cost of leaf tobacco had shown decreasing tendency according to increasing farm sizes. To promote the international market competitiveness of leaf tobacco producing farms, labour saving production technologies and cost effective farm size to decrease tobacco production cost should be developed.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.1
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• pp.166-174
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• 2009

Gijang Sea is located on the southeastern coast of Korea. This study establishes a basic system to identify optimal sites for the wave power generation. To achieve this goal, the field measurements were made at the field site in front of Dong-am fishing port at Gijang. In addition, we analyzed the offshore wave data at the Donghae buoy operated by Korea Meteorological Administration(KMA) and compared the data with the wave characteristics in Gijang Sea. The main results were as follows. In winter, the wave direction in Gijang Sea ranged between east and south($90{\sim}180^{\circ}$). The main wave direction was east($90^{\circ}$). The Significant wave heights and periods were under 2 m and $5{\sim}15$ sec, respectively. A comparison of water depth and wave direction constitutes one(condition) of the important parameters for selecting the optimal site for the wave power generation.