• Journal of IKEEE
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• v.24 no.1
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• pp.46-51
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• 2020

With Wi-Fi and Bluetooth connectivity becoming more common in today's handheld mobile devices, single-chip multi-radio combo-modules, which integrate two or more heterogeneous wireless radios on a single chip, are becoming more and more popular. The key requirement for combo solutions is that the quality of the user experience (QoE) must not be compromised by degrading connectivity performance. Therefore, characterizing and understanding the behaviour of combo-module is of vital importance to ensure this requirement in various environments. In this paper, we investigate the impact of the use of combo-modules on the performance of mobile video streaming over a Wi-Fi network. Our study reveals that the use of combo-modules incurs considerable side effects on QoE for mobile video streaming applications when the Wi-Fi and Bluetooth operate at the same time in the 2.4GHz ISM band. We reveal that rate-based adaptive algorithms, including the most popular adaptive bitrate streaming MPEG-DASH, is more severely affected by this phenomenon than buffer-based adaptive algorithms.

• Journal of the Korea Society of Computer and Information
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• v.10 no.4 s.36
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• pp.123-132
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• 2005

A version control system is used in a rapidly changed environment or a program which developed in a complicated environment. And configuration thread information supporting and it's processing method has an important part in version control. Configuration thread tool such as a system model of DSEE, a view of ClearCase, a label of SourceSafe, and the package of CCC/Harvest have applied to formalized configuration rule by user and obtained a desired configuration information of the version. But it is a problem of configuration thread in supporting information that we. in this method. can't know a exactly well-defined configuration rule information and a predefined information. And these information have a demerit that can't supported the close connection along with undefined version and a meta-information. In this paper. we have modeling a system for these problems to solve and a efficiently configuration thread supported. We also proposed a mixed retrieval model included a boolean retrieval model and a vector retrieval model for support efficiently configuration thread information. We applied and designed the libraries using extended facet method.

• Journal of the Korea Society for Simulation
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• v.20 no.4
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• pp.91-96
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• 2011

As the user's demand for ultra high-speed wireless internet has increased, the standardization, research and development of future mobile communication systems have been done for several years. IMT-Advanced system which is called fourth generation mobile communication should support the data rate of 1 Gbps for nomadic users and 100 Mbps for mobile users. Also, the system should hold call connection at the mobile speed of 350 km/h. Meanwhile, since Doppler spread is linearly proportional to mobile speed, high mobility leads to the increase of interference between subcarriers and the deterioration of detection performance consequently. In this paper, we evaluate and analyze detection probability with respect to equalization methods in time-varying channels under system parameters complying with IMT-Advanced requirements. According to computer simulation conducted by varying mobile speed and code rate, MMSE based equalization can mitigate performance degradation of IMT-Advanced system considerably in time-varying channels.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.103-109
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• 2005

Research about P2P system have recently a lot of attention in connection of form that pass early Centralized P2P and is Decentralized P2P. Specially, Structured P2P System of DHT base have a attention to scalability and systematic search and high search efficiency by routing. But, Structured P2P System of DHT base have problem, file can be located only their unique File IDs that although user may wish to search for files using a set descriptive keyword or do not have the exact File ID of the files. This paper propose extended-CAN mechanism that creates File ID of Contents base and use KID and CKD for commonness keyword processing to support keyword search in P2P System of DHT base.

• Proceedings of the KIEE Conference
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• summer
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• pp.1489-1491
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• 2004

A guard lamp system has been installed at the PV positive center, located at Gwangju in Korea. Digital environment that is represented to internet is displacing business way of industry and business achievement way with the fast speed being giving great change on life whole, improve existence business process utilizing internet and Web connection technology, information superhighway to tradition industrialist manufacture and e-transformation's propulsion that wish to maximize productivity and administration efficiency is spread vigorously. In this paper, we wish to accomplish generation equipment's heighten stability and believability through remote monitoring and control of guard lamp system. This paper describes the design of the monitoring system for the sensing data and indirect controlling of the guard lamp system. Most of the conventional monitoring systems depend on the special hardware and software. The essential design of monitoring system is to provide the convenience for the user and the portability for the system. In order for the system to fulfill its requirements, it was designed using Labview GUI facility based on the Windows 2000 environment of IBM PC compatible and Add-oncard based on the TCP/IP Protocol. Advantage of the monitoring system are a personnel expenses curtailment effect, of the place restriction and unmanned system of the generationplants, etc..

• KIPS Transactions on Computer and Communication Systems
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• v.1 no.3
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• pp.205-218
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• 2012

Mobility management of the mobile nodes and provision of seamless handover is crucial to an efficient support for the global roaming of the mobile nodes in next-generation wireless networks. Mobile IPv6 and mobility management in extended IP layer, which highly depend on traffic characteristics and user mobility models, were proposed by the IETF. Therefore, to evaluate the in-depth performance about these factors is important. Generally, the performance of IPv6-based mobility management protocol is evaluated through simulation. This paper shows the correlation between network parameters and performance metrics through numerical results, which is investigated how influence handoff latency and packet loss. And this paper uses mathematical analysis of the system parameters, such as the subnet residence time, the packet arrival rate and delay in wireless connection through the analytical framework which evaluate the performance of IPv6-based mobility management protocol.

• Archives of design research
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• v.12 no.2
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• pp.19-28
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• 1999

Current technology does not emphasize closer connection through group collaboration, but rather underlines the distances and separations that are visible in today's society. As the interpretation of our territory of life which is still based on the model of the 'physical' of industrial era is no more valid, a different 'sense of belonging' corresponds to this new notion of territory. The main idea is how to make the sense of community to connect actual space with one child from each place. Therefore, the subject of this thesis is to design the system making children from distance to be closer, developing 'learning community' connecting with two classes across the globe. The contents include its studying in respect to the development of a non-geographical 'learning community' based on co-evolution, and to the system design of conceptual models for the community. In conclusion, the physical interface design is suggested to let user develop accurate mental models of the system.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.823-826
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• 2008

This paper shows linkage management for external services. There are many services for specific entities such as DBLP and OntoWorld. OntoFrame, as a Semantic Web-based research information service portal, aims at one-stop service in ways that it connects external services with hyperlinks. For managing the linkage, linkage rules are manually edited by human administrators and automatically verified and tested by linkage management system. It consists of linkage rule management, linkage rule verification, linkage test, and dynamic link generation. Linkage rule management creates and edits linkage rules to connect external services on the Web. After finished rule editing and verification step, linkage management invokes linkage test with entity list. Only valid links are visible to enable users to click on our system, and thus it increases user's reliability on the system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.5
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• pp.447-453
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• 2004

In this paper, we propose a new system to block harmful Internet information based on IP spoofing. The proposed system is located on a organization's internal network and monitors all outgoing traffic and lets all this traffic go outside. Once the proposed system detects a host's access to a harmful site, it sends the host a pseudo RST packet that pretends to be the response from the harmful site, and prevents the connection between the host and the harmful site. The proposed software system is installed on only a server, and need not be installed on user hosts at all. Thus we can maintain and upgrade the blocking system easily. The performance evaluation of the proposed system shows that it effectively blocks the access to the harmful sites. Since the proposed system is based on IP spoofing, it can be used badly as a hacking tool. Finally we propose some methods to eliminate this possibility.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.11
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• pp.2127-2134
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• 2007

The electronic learning helped a learner to overcome the time restriction by providing mobility, instantly and flexibility but the restriction in connection with space on cable computer remained unsolved. Accordingly, the electronic learning has tendency to change into mobile learning environment which allows a learner to overcome time and spatial restriction. However, these mobile devices have a limitation to awareness of learning contents provided over the realtime video movie due to its small display size. Therefore, this paper suggests a technique according to the following priority: for a real time learning image, extract region of study for region of interest, rescale the real time image to its proper size suitable for the display device, and then make it displayed on a wireless PDA. As a result of the experiment, we reduced the calculating time by sampling the field centering on learning contents adaptively and computing the field best suited for device size of the user effectively.