• Journal of the Korea Society of Computer and Information
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• v.17 no.6
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• pp.145-152
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• 2012

Due to the large sizes of streaming media, previous delivery techniques are not providing optimal performance. For this purpose, video proxy server is employed for reducing the bandwidth consumption, network congestion, and network traffic. This paper proposes a fast distributed network file system using state transition model in the media streaming system for efficient utilization of video proxy server. The proposed method is composed of three steps: step 1. Training process using state transition model, step 2. base and decision probability generation, and step 3. storing and deletion based on probability. In addition, storage space of video proxy server is divided into each segment area in order to store the segments efficiently and to avoid the fragmentation. The simulation results show that the proposed method performs better than other methods in terms of hit rate and number of deletion. Therefore, the proposed method provides the lowest user start-up latency and the highest bandwidth saving significantly.

• Journal of Digital Contents Society
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• v.15 no.1
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• pp.113-120
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• 2014

In recent years, devices using the smart ponwa IT service is activated, to research how the fusion of two or more devices will be able to be interest in the soybeans. One of them in the mobile sector through the development of network and hardware digital geo-spatial map of the rapid advances being made and the computer, how do you map data to efficiently simulate a 3D environment, providing services through a virtual environment focused on whether be. In this study, augmented reality and GIS (Geographic Information System), SLM (Static LOD Model) that combines augmented reality technology on the basis of the basic concepts and approaches in geographic space and how Augmented Reality Based on this interpretation of the relevant content What to do in the development and utilization has a purpose. In this study, the conventional SLM 3DS model data structure of a data format conversion of the proposed possibilities for analyzing and, SLM model generation and format of the existing three-dimensional visualization tools SLM model format for converting a format to a model function, and visualization features. In addition, 3D virtual model to propose a format for efficiently making.

• Journal of The Korean Association For Science Education
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• v.37 no.5
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• pp.835-846
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• 2017

The purpose of this study is to investigate the perceptions of scientifically gifted middle school students about their engineering design process according to gender and talent division. The instrument in surveying their perceptions about the engineering design process consists of 24 items (Likert 5 point type) five domains: problem definition, information collection and utilization, idea generation, inquiry performance, and teamwork (communication, cooperation, leadership). A total of 102 scientifically gifted students participated in the survey, according to gender (69 males and 33 females) and talent divisions (physics, biological sciences, software, mathematics, space-geological sciences, and chemistry). They had a high level of awareness of their engineering design ability. It is necessary to develop a customized gifted-education program so that their talent in their field of interest can be fully displayed according to the gender and talent division. In addition, the teaching and learning methods and strategies of the engineering design program for the scientifically gifted middle school students should be established to fully reflect the practical needs of the talented.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.262-270
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• 2004

Basic experiments were carried out using the THT-IV low-power Hall thruster to examine the influences of magnetic field shape and strength, and acceleration channel length on thruster performance and to establish guidelines for design of high-performance Hall thrusters. Thrusts were measured with varying magnetic field and channel structure. Exhaust plasma diagnostic measurement was also made to evaluate plume divergent angles and voltage utilization efficiencies. Ion current spatial profiles were measured with a Faraday cup, and ion energy distribution functions were estimated from data with a retarding potential analyzer. The thruster was stably operated with a highest performance under an optimum acceleration channel length of 20 mm and an optimum magnetic field with a maximum strength of about 150 Gauss near the channel exit and with some shape considering ion acceleration directions. Accordingly, an optimum magnetic field and channel structure is considered to exist under an operational condition, related to inner physical phenomena of plasma production, ion acceleration and exhaust plasma feature. A new Hall thruster was designed with basic research data of the THT-IV thruster. With the thruster with many considerations, long stable operations were achieved. In all experiments at 200-400 V with 1.5-3 mg/s, the thrust and the specific impulse ranged from 15 to 70 mN and from 1100 to 2300 see, respectively, in a low electric power range of 300~1300 W. The thrust efficiency reached 55 %. Hence, a large map of the thruster performance was successfully made. The thermal characteristics were also examined with data of both measured and calculated temperatures in the thruster body. Thermally safe conditions were achieved with all input powers.

• Journal of the Korean Geographical Society
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• v.52 no.1
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• pp.55-71
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• 2017

This paper points out the semantic unclearness of the jargon "cluster" and suggests the substitution of "industrial cluster" for "cluster". Industrial cluster is the intersection of industrial agglomeration and cluster phenomenon while the actual concept of cluster includes not only industry cluster but also political administration cluster, science research cluster, art cluster, religion cluster, education cluster, etc. Partially reconstructing the concept and significance of industry cluster, industrial cluster is a geographic agglomeration of interconnected productional businesses in a particular industry, forming close industrial networks. The advantage of the agglomeration includes reducing the transaction cost between the businesses, promoting technological innovation and dispersion, facilitating the utilization of the professional workforce, sharing and connecting the external customer. Moreover, this paper discusses the range of the industrial cluster and its distinctness from the other similar concepts. There is a need to discriminate it from the other related jargons and to clarify their relationship. In particular, there is a task to eradicate the mixed usage of industrial cluster with the jargons related to space for learning and innovation.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.643-646
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• 2007

As increase of the land price at downtown area, it makes people more and more interested of improving the space utilization such as makes buildings bigger, deeper and higher. Therefore, the importance of the underground construction which is the basic principle has been increased. As constructors have to complete underground construction as soon as possible with the minimum costs, they concentrate on the whole process of underground structure. Although they makes every these efforts, construction failure still happen because of the uncertainty of the condition of soil and the unexpected danger of underground construction. To make matter worse, there are only some examples without detailed information like 'how much this breakdown damage to the construction?' so it is the anther problem that most of people doesn't recognize the economical negative impact of underground structure breakdown. This report would make people understood the importance and risk of the underground construction by showing some analysis which was assumed from the real accidents.

• Journal of Information Technology Services
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• v.16 no.1
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• pp.139-162
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• 2017

Museums contain a significant meaning as a place that reflects empirical knowledge that have been accumulated socially and scientifically in overall life of the public and provides the opportunity to enjoy prestigious culture, while serving as the extended place of education. The first objective of this study is to increase the accessibility of general public through the development of online museum programs as service contents and to present the ultimate direction the development of in art appreciation contents that can effectively expand the infrastructure of culture and art. Second, the effectiveness of online art appreciation programs by registered private museums, which continuously develop smart media-based online museum contents and systemization of archive as the distribution rate of smart devices is increased due to generalization of digital environments, was analyzed by each case to examine the objective distinctions strategies. Third, in terms of museum visitors and smart contents users, this study examines the expected effects of popular distribution by seeking various ways that can enhance the desired exhibit appreciation and autonomous utilization of educational programs, while not being restricted by the physical accessibility and limitation of space at the museums. The subjects of this study included cases of BoroomSan Museum, Savina Museum of Contemporary Art, Imageroot, Sangwon Museum of Art, Hello Museum, etc. and the online smarts contents art appreciation educational programs by registered private museums were analyzed. Results expected to achieve from such processes are as follows. First, the possibility to expand cultural participation in museum exhibition appreciation and museum education infrastructure became widen. Second, the educational program resources can be utilized as the culture and art asset that strengthens the museums' responsibilities in their social role. Third, museum archive can be constructed in more systematic way, and the efficiency of museum archive system can be enhanced to maintain the museum collection database in a consistent format. Fourth, the museum's smart contents users' continued access to museum's online contents may induce the exhibition effect of the site and voluntary participation in education, and can also expect an economic synergy effect as the users become potential visitors that may actually visit the museum in the future.

• Journal of Satellite, Information and Communications
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• v.7 no.1
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• pp.39-47
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• 2012

Currently, most of the frequency spectrum resources are allocated and due to the lack of frequency, low frequency band, optimal for wireless communication environment is not used. Therefore, Cognitive Radio (CR) is a critical issue to solve the spectrum scarcity and to improve frequency spectrum utilization in wireless communication. In this paper, we implement data transmission and receive in a real CR system using the USRP(Universal Software Radio Peripheral) board and GNU Radio package of an open source development kit. Concretely, we detect the Primary User by spectrum sensing, and then we send Primary User information to the database. After receiving the information, because the database already sent optimal transmit power, bandwidth and channel information to CR equipment, CR can communicate without any interference to Primary User.

• Journal of the Korean Institute of Landscape Architecture International Edition
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• no.2
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• pp.102-108
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• 2004

In the city of Asia like Seoul and Tokyo, aggregate power is poured into the city making which is suitable in new age. Large-scale re-development is active in various places as the present condition, As for the various East Asian cities, high-level utilization conversion of the land and high conversion of the building are advanced. As for these realities, the re-development is advanced in the situation that has not been clarified enough though it is true that green of the city has decreased. This research was aimed at the clarifying the allocation of greenery when proceeding with town planning projects by quantifying the possibility of allocating greenery in the form of rooftop landscaping in redeveloped areas. Moreover, the distribution of the green in the re-development region was calculated and the coexistence level of green space was calculated, The realities of a desirable green were clarified in the spectacle by understanding a sight and spatial continuousness in the green. In order to clarify the potentiality of roof greenery revaluating, the research was conducted by analyzing from aerial photographs, in Tokyo and Seoul, And the flow of the research was conducted by selection of research object area, taking pictures, acquisition of the aerial photography, rearrangement the data and the analysis. As a result, I was able to prepare a land vegetation coverage classification chart and obtain data pertaining to the level of urban and green tract of land for the researched cities of Tokyo and Seoul. By analyzing this data, we were able to indicate patterns of greenery unable to be obtained through data from ratio of vegetation coverage and ascertain the effectiveness of rooftop landscaping.

• Journal of the Korean Institute of Landscape Architecture
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• v.26 no.3
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• pp.258-266
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• 1998

The purpose of this study is to investigate the actual conditions, to find problems, and to present an improvement plan of interior landscape in the subway stationis. Moreoiver, it will presume the possibilties to develop the subway and ways to utilie underground space effectively. The results are summarized as follows A light intensity was recorded 0-100 Lux as the lowest light and 500 Lux below as the highest in 61 subway stations. An average temperature of 12 $^{\circ}C$and an air humidity of 38% were recorded over a 4 month period from January to April, but includes a drastic variaton between -8.5$^{\circ}C$ and 21.5$^{\circ}C$. Soil acidity of pH 7 below and soil moisture of 1-2 wet degree were apeared in subway stations mostly. Plant forms consisted of artificial flower & flower. Plant species were recorded at a total of 54 species and appeared in the order of Araucaria heteropylla, Ophiophogon jaburan, Aspidistra elatior cv. 'Asahi' and Hedera helix. Plant height was, for the most part, below 0.5m. Plant species that was fined of conditions were Palm, Camellia japonica, Araucaria heterophylla as a high plant, dracaena fragrans, dracaena deremensis cv. Wakneckii as a middle plant, and Ophiopogon jaburan, Hedra helix, ytomium falcatum, Aspidistra elatior cv. Asahi as a low plant. It used to water materials such as small pool, small cascade, water cycles and natural materials such as natural rock, small rock, sand, bark and animal materials such as squirrels, birds, goldfish as an object for plants in the subway stations. From these actual conditions, First of all, It must make up physical environments such as light, temperature humidity, soil for plant growth, and is important to chooce suitable indoor plants and draw up systematic management in the subway environments. Also, it change plants frequently and uses variable objects for subway stationi individuatism, Moreover, indoor plants with strong environmental adaptation abities such as shade tolerance, drought tolerance and cold tolerance need to develope variable species possibly. If these improvements occur, utilization and amenity of subway stationis will increase, according to the use of interior landscape.