• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.11
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• pp.939-954
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• 2013

Korean military is developing the next generation military satellite communications system in order to achieve the requirements of future military satellite communication such as high speed, high capacity, survivability, all IP networking, and on-the-move. In this paper, we survey and analyze the research interests about optimal resource allocation and IP networking such as MF-TDMA, random access, satellite IP routing, and PEP. Conventional researches have focused on the increase in channel throughput and efficiency. In addition to these measurements, we consider heterogeneous satellite terminals, full mesh topology, distributed network, anti-jamming, and the like which are the special characteristics of the next generation military satellite communications system. Based on this, we present key research issues and evaluation on the issues by simulation.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.4
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• pp.13-20
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• 2009

RFIDs have been used a lot of control systems such as library and security efficiently. Unlawful parking control is one of them and it will bring a lot of merit. Especially, it can be used vehicles. If a vehicle comes to unlawful parking place, reader system read the tag of a vehicle. RFID reader confirm the vehicle and record current time at the same time send information related the vehicle to the server system. After, it can be activated. If the vehicle move from unlawful parking place, RFID reader record departed time. In this paper, we proposed a monitoring system for unlawful parking cars. Especially, it is certain that this proposed modelling is very efficient and correct.

• The Mathematical Education
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• v.45 no.3 s.114
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• pp.295-313
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• 2006

University teacher education programs have sought for ways of how to improve student teaching in order to supply mathematics teachers with practical theory to achieve the goals of the current educational reform in school mathematics. In this context, the purpose of this research is to investigate the effect of student teachers' teaching experience in the after-school mathematics programs and the ways of how to develop the after-school learning programs as an effective site for learning to teach based on the inquiry into student teachers' own teaching experience. For the purpose, data were collected through the interviews with the student teachers who had taught after-school mathematics class. In addition, data were collected through survey, class observation, and seminal meetings with the student teachers in order to supplement the findings from the interview analysis. Data analysis focused on the student teachers' experience with teaching in after-school mathematics classes, that is, what and how they had learned as teachers, what kinds of difficulties they encountered in their teaching and supports that they expect to improve their learning through teaching. The analysis shows that the teaching experience in the after-school programs had positively contributed to their development as future mathematics teachers. Specifically, the after-school programs provide the site for learning through teaching at the early stage of teacher education program. The after-school programs provided the students teachers for the opportunity to participate peripherally in educational practice of school. Through the participation, the student teachers developed positive attitudes toward teaching career and became to have more solid ideas about how to teach mathematics. Based on the analysis, this research provides following suggestions concerning how to improve student teaching. First, it is necessary to provide student teachers to participate into the practice of teaching at the early stage of teacher education programs. Second, it is important to give students teacher opportunity to participate in teaching at peripheral and legitimate positions. Finally, it is necessary to construct mentoring networks to support student teachers to move from a peripheral position toward a center of teaching practice.

• Korean Institute of Interior Design Journal
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• v.22 no.5
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• pp.258-266
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• 2013

Rapidly aging society extends the span of aged life of the elderly people longer than before and this trend raises the issue of holistic health of the aged including their physical, psychological and social health making it necessary to study for environmental development to support this trend. This study intends to explore the direction of residential planning to support the deterioration phenomenon of social networks due to aging. Social networks here are treated as basic conditions for social health. This study researched the diverse types of elderly housings in preparation for the aged society and their spatial characteristics, social affordance characteristics and their potentials for social interactions from the viewpoint of their social relations. literature studies with contents analysis method was used. The results of this study were arranged primarily according to the characteristics of social relations by types of housings. Socially integrated types of housings can be found as inclusive housing type as they have both social characteristics that can be found in houses in general and the elderly housings, they should be considered as desirable types in Korea where collective houses are most popular. Form the existing housing plans housing plan direction should move toward socially integrated housing plans that can protect the elderly people collectively and the direction of housing plans here means the direction from more macro-perspective viewpoint. Therefore, the results of this study are meaningful in adding interpretation from the viewpoint of social relations respective housings and promoting housings for the elderly people more desirably.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.10A
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• pp.1057-1064
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• 2007

Cognitive radio(CR) technique which utilizes empty frequency bands allocated to private business but not being used temporally has been researched. According to the standard, CR users detect the primary user using the same channel, CR users should move to the another channel to guarantee the primary user's decodability. Thus, CR systems cannot use the same channel and support the CR user's QoS(Quality of Service) during the channel moving time. In this paper, we propose a radio resource sharing method that CR basestation controls the transmission power with the primary user's SNR(Signal to Noise Ratio) to increase the spectral efficiency of area and to minimize the outage of CR users. In addition, computer simulation demonstrates show that the proposed method improved spectral efficiency of area and decreased outage probability of CR users.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10B
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• pp.891-899
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• 2006

Generally, a geographical area consists of many regions called cells in wireless networks. Each mobile host(MH) in a cell communicates with a base station(BS) located in the center of the cell. The BSs are connected to each other by a static wired network. Since users are expected to move around during communication sessions, one of the most important QoS factors is related to the handoff. But, the handoff could fail due to unavailability of sufficient bandwidth in the next cell. As the individual cell size gradually shrinks to accommodate increasing the number of MHs, the probability of successful handoffs can be dropped. In this paper, we suppose a bandwidth reservation method to guarantee MHs against connection failure in case of frequent handoffs. This method predicts the mobility based on the geographical information and assigns the bandwidth reservation in proportion to the speed of MHs' motion. As a result, we can expect more exact moving path of MH and to reduce the waste of bandwidth.

• Journal of Internet Computing and Services
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• v.1 no.1
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• pp.35-46
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• 2000

One of the main chalenges in personal communication services (PCS) is to locate many mobile terminals that may move frequently from place to place. Such a system operation is called location management. Many network signaling traffic, and database queries are required to achieve such a task. Several strategies have been proposed to improve the efficiency of location management. These strategies use location register databases to store the current location on mobile terminals, and are vulnerable to failure of the location registers. In this paper, we propose a fault-tolerant pointer forwarding with distributed home location register (FT-RFDHLR) to tolerate the failure of location registers. The performance of the proposed method is evaluated by an analytical model, and is compared with thew pointer forwarding with the single home location register (PFSHLR), the pointer forwarding with distributed home location register (PFDHLR), Biaz's bypass forwarding strategy (BFS) and two-path forwarding strategy (TPFS).

• Journal of Information Technology Services
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• v.16 no.4
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• pp.137-148
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• 2017

Researches on the Artificial Intelligence has been explosively activated in various fields since the advent of AlphaGo. Particularly, researchers on the application of multi-layer neural network such as deep learning, and various machine learning algorithms are being focused actively. In this paper, we described a development of an artificial intelligence Janggi game based on reinforcement learning algorithm and MCTS (Monte Carlo Tree Search) algorithm with accumulated game data. The previous artificial intelligence games are mostly developed based on mini-max algorithm, which depends only on the results of the tree search algorithms. They cannot use of the real data from the games experts, nor cannot enhance the performance by learning. In this paper, we suggest our approach to overcome those limitations as follows. First, we collects Janggi expert's game data, which can reflect abundant real game results. Second, we create a graph structure by using the game data, which can remove redundant movement. And third, we apply the reinforcement learning algorithm and MCTS algorithm to select the best next move. In addition, the learned graph is stored by object serialization method to provide continuity of the game. The experiment of this study is done with two different types as follows. First, our system is confronted with other AI based system that is currently being served on the internet. Second, our system confronted with some Janggi experts who have winning records of more than 50%. Experimental results show that the rate of our system is significantly higher.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.8
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• pp.5233-5241
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• 2014

This study analyzed the system level performance of the Mobile WiMAX-based TICN, and the effects of the use of BS-OTM in terms of the throughput of individual users as well as the overall system, assuming that other stationary BSs are distributed randomly. When BS-OTM is used, the CINRs decrease due to the additional interference from the BS-OTM from the perspective of SSs that are served by the same BS as when OTM BS is not used. On the other hand, from the perspective of SSs that had low CINRs, the CINRs increase significantly due to the new service from BS-OTM. Considering both effects, the cell throughput can be increased using BS-OTM. The CINR distribution and throughput of the overall system, changing the carrier frequency, position and velocity of the BS-OTM were also evaluated.

• The Journal of the Korea Contents Association
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• v.12 no.9
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• pp.16-26
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• 2012

A path generation method considering the tendencies of users is required because users has the preferred routes through the properties such as time, distance, and congest. The existing method must input the additional information about user's tendency to generate path considering moving tendencies. However, mobile device have the inconvenient interface. Therefore users are reluctant to input additional information for path generation. In this paper, we propose the path generation method considering the tendencies of users without additional input of users tendencies. To show the superiority of the proposed method, we compared it with shortest distance or time path through performance evaluation.