• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.185-188
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• 2016

The percentage share of mobile gift card certificate in the gift card market has increased significantly each year. But from a consumer perspective mobile gift card certificate has several problems. Specifying unfair terms in Fair Trade Commission has improved slightly, but the problem is not replaced with the equivalent authority that issued the vouchers can not be solved. The exchange between users the most realistic way to solve this problem is to create an environment as possible. In conclusion, The deal will be possible to build a mobile gift card certificate brokerage trading in a convenient and reliable P2P-based. If the System for mediating transactions of a mobile gift certificate has created a healthy retail environment, such as the expansion of the voucher market, reduce social costs may be creating.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.9B
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• pp.947-954
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• 2009

In mobile ad hoc networks, service discovery to search for an available service is an important issue. In this paper, we propose an efficient service discovery protocol that is combined a dht-based service discovery scheme and a P2P caching-based information spreading scheme. Proposed scheme store key information in hashed zone and search services using it's information. To search quickly a service, it use its physical neighbors information which collected by 1-hop hello message between a node and its physical neighbors. We do not use a central look up server and do not rely on flooding. Hence, it uniquely balanced all node's load in mobile ad hoc networks and reduced the number of messages exchanged, network load and response time. The simulation results show that our protocol outperforms DHT-based and flooding protocols.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04d
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• pp.118-120
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• 2003

유무선 인터넷 기술의 발달로 인해, 네트워크 전반에 걸쳐 산재해 있는 개인 정보에 대한 공유 및 교환에 대한 요구가 점차로 증가하고 있다. 본 논문에서는 이동에이전트 기반의 peer-to-peer(P2P) 네트워킹을 위한 새로운 기법이 설계되고 구현된다. 설계된 시스템은 이동에이전트를 사용함으로써, 냅스터 및 그 누텔라로 대표되는 기존의 혼합형 P2P와 순수형 P2P에서 발생하는 문제점들을 보완시킨 새로운 기법이며, 혼합형과 순수형 모두에 적용이 가능하다. 또한 분산 정보 공유 및 교환을 위한 응용 개발의 용이함을 위해 다양한 고급의 AH들을 제공하고 있다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.8
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• pp.1640-1646
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• 2004

In this study, we propose the multiple VoIP service networks for P2P network environments based on portable internet. We found that voiceservice using portable internet is possible for real time services. After we designe the multiple VoIP service networks for P2P network environments based on portable internet, evaluate the performances. from the performance evaluations, we found satisfactory results and so we can expect the possibility of the portable internet services.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2147-2154
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• 2014

JXTA does not need to be managed by the central server, and has the property that can communicate with any device that is connected to the network. Thus, JXTA can be applied to the communication between heterogeneous P2P systems. This paper deals with the design of a data exchange system utilizing the JXTA's foregoing property, which is able to connect P2P systems with different protocols and APIs.

• ETRI Journal
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• v.35 no.6
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• pp.1084-1093
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• 2013

problem of pedestrian localization using mobile nodes containing impulse radio ultra wideband (IR-UWB) is considered. IEEE 802.15.4a-based IR-UWB can achieve accurate ranging. However, the coverage is as short as 30 m, owing to the restricted transmit power. This factor may cause a poor geometric relationship among the mobile nodes and anchor nodes in certain environments. To localize a group of pedestrians accurately, an enhanced cooperative localization method is proposed. We describe a sequential algorithm and define problems that may occur in the implementation of the algorithm. To solve these problems, a batch algorithm is proposed. The batch algorithm can be carried out after performing the sequential algorithm to linearize the nonlinear range equation. When a sequential algorithm cannot be performed due to a poor geometric relationship among nodes, a batch algorithm can be carried out directly. Herein, Monte Carlo simulations are presented to illustrate the proposed method and verify its performance.

• Bulletin of the Korean Chemical Society
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• v.26 no.2
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• pp.297-302
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• 2005

The determination of total phenols was accomplished by capillary-high performance liquid chromatography (capillary-HPLC) after nitrosation of the U.S.E.P.A. classified 11 priority pollutant phenols, using the nitrosated parent phenol (POHNO) as a reference for calibration. The optimum mobile phase composition for this analysis was found by examining the effect of changing the percentage of acetonitrile (MeCN) in the mobile phase on retention factors (k values) and peak intensities. As MeCN percentage was increased, k values were reduced and peak intensities were generally increased. From the results obtained, it was found that the optimum mobile phase was 90%(v/v) MeCN solution at pH 8.0, the detection wavelength of 400 nm, and a detection limit (D.L., concentration at signal to noise ratio (S/N) of 3.0) of 4.5 ${\times}$ $10^{-7}$ M. In addition, 10 of the 11 phenols present in mineral or waste water were separated after the nitrosation by capillary-HPLC. The optimum mobile phase for separation was a 40%(v/v) MeCN solution at pH 5.0.

• Journal of Internet Computing and Services
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• v.10 no.4
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• pp.189-198
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• 2009

Unstructured peer-to-peer systems are most commonly used in today's internet. But file placement is random in these systems and no correlation exists between peers and their contents. There is no guarantee that flooding queries will find the desired data. In this paper, we propose to cluster nodes in unstructured P2P systems using the agglomerative hierarchical clustering algorithm to improve the search method. We compared the delay time of clustering the nodes between our proposed algorithm and the k-means clustering algorithm. We also simulated the delay time of locating data in a network topology and recorded the overhead of the system using our proposed algorithm, k-means clustering, and without clustering. Simulation results show that the delay time of our proposed algorithm is shorter compared to other methods and resource overhead is also reduced.

• Journal of the Korea Convergence Society
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• v.12 no.11
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• pp.457-466
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• 2021

This study sought to identify the effectiveness of training programs by developing mobile app-based training programs to enhance memory, attention, and language function, which is known to be vulnerable to menopause women. It was conducted on 40 Climacteric woman between 40 to 60 years complaining about cognitive function decline. The mobile app-based cognitive training was an 8 week program. There were a total of 24 sessions and each session took 20-30 minutes, three times per week. The survey was carried out including a baseline study pre and post intervention study. The research variables were objective cognitive function (overall cognitive function, memory, attention, and language function), subjective cognitive function and quality of life. The cognitive training program showed a significant increase in overall cognitive function(t=-8.688, p<.001), memory(t=-4.765, p<.001), attention : number of correct answers(t=-7.293, p<.001), language high frequency response speed(Z=-2.179, p=.036), language low frequency response speed(Z=-2.737, p=.009) and quality of life (t=-3.358, p=.002). However, there was no significant difference in the scores for subjective cognitive function. The cognitive training program was found to be an effective intervention for improving the cognitive function of Climacteric women. It could be used as a cognitive intervention tool that is accessible at home without expert help.

• Journal of Digital Convergence
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• v.12 no.2
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• pp.335-341
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• 2014

To play the networked video contents in a client's mobile device in real time, the contents should be delivered to it by the contents server with streaming technology. Generally, in a server-client based commerce model, the server is in charge of both the authentication of the paid customer and distribution of the contents. The drawback of it is that if the customers' requests go on growing rapidly, the service quality would be degraded results from the problems of overloaded server or restricted network bandwidth. On the contrary, in P2P based networks, more and more the demand for service increasing, the service quality is upgraded since a customer can act as a server. But, in the P2P based network, there are too many servers to manage, it's possible to distribute illegal contents because the P2P protocol cannot control distributed servers. Thus, it's not suitable for commercial purposes. In this paper, the dymanic group authentication scheme is proposed which is suited to P2P based applications. The proposed scheme consists of group based key generation, key update, signature generation and verification protocols. It can control the seeder's state whether the seeder is joining or leaving the network, and it can be applied to hybrid P2P based commerce model where sales transactions are covered by the index server and the contents are distributed by the P2P protocol.