• Journal of Internet Computing and Services
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• v.2 no.5
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• pp.41-47
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• 2001

This paper deals with an EJB-based database agent(component) used to define workflow processes, which is a core function of the e-Chautauqua workflow management system that is an on-going research product. We describe about how to design and implement the EJB-based DB agent that is deployed on EJB server as a component. The agent is located between the build-time clients and the database system, and manages database accesses, such as retrieves and stores, from the workflow definition components. Through the EJB technology, we are able to accomplish a stable database agent that can be characterized by the distributed object management, reliable recovery mechanism from system failovers, reliable large-scale transaction management, and the security functions.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1324-1331
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• 2008

Recently, landslides have frequently occurred on natural slopes during periods of intense rainfall. With a rapidly increasing population on or near steep terrain in Korea, landslides have become one of the most significant natural hazards. Thus, it is necessary to protect people from landslides and to minimize the damage of houses, roads and other facilities. To accomplish this goal, many landslide prediction methods have been developed in the world. In this study, a simple landslide prediction system that enables people to escape the endangered area is introduced. The system is focused to debris flows which happen frequently during periods of intense rainfall. The system is based on the wireless sensor network (WSN) that is composed of sensor nodes, gateway, and server system. Sensor nodes and gateway are deployed with Microstrain G-Link system. Five wireless sensor nodes and gateway are installed at the man-made slope to detect landslide. It is found that the acceleration data of each sensor node can be obtained via wireless sensor networks. Additionally, thresholds to determine whether the slope will be stable or not are proposed using finite element analysis. It is expected that the landslide prediction system by wireless senor network can provide early warnings when landslides such as debris flow occurs.

• Convergence Security Journal
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• v.8 no.1
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• pp.49-56
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• 2008

Recently, Phising attack uses trick of URL and sites, and technical concealment method which infiltrates sophisticated malicious code. However, sometimes Phising security technology cannot cover all of Phising methods. Consequently, this research proposes inspection to solve this problem. First, we can install Proxy server for a strong open information exchange of web environment between web servers and clients. Therefore, it compares and analyzes harmful site and Phising URL with White domain list, and filters them. Finally, designs for stable web based information so that we can block Phising with least regulation and active control. So the purpose of this paper is introducing this design system and structure, and inspect them.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.1
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• pp.150-157
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• 2016

In this paper, a control system for E-bike based on IOT was developed, which collects and monitors information of states of E-bike and surrounding environments from several sensors and control devices in E-bike, and informs the possible dangers to rider when riding the E-bike. Developed electronic control system can manage battery efficiently, obtain battery's remaining power in real-time and provide possible riding distance to rider. It makes possible for rider to schedule near optimal riding route in terms of battery usage and respond quickly to battery discharge. Results of applying developed system to E-bike show that according to driving-mode, possible driving distance can be calculated efficiently and using user application App, real-time driver position marking and driving route searching functions lead to energy efficient E-bike driving. Later we will endeavor to integrate BMS, ECU, smart-phone and PC(server) to provide stable driving system based on various driving information of E-bike.

• Journal of Internet Computing and Services
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• v.7 no.5
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• pp.33-41
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• 2006

Wireless LAN is intrinsically weak in security of transmissions. WPKI (Wireless Public Key Infrastructure) is a well known Method to deal with the security issues in wireless LAN. The authentication required by the method becomes a source of unrellability of the hand-off performance. This paper suggests a solution to overcome the instability while using the WPKI technique, Prior to getting into the next region, a station is provided with the keys of the surrounding regions so that the possible delay problem can be avoided during the actual hand-off time. Thereby the hand-off instability can be solved in the WPKI framework.

• Journal of information and communication convergence engineering
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• v.8 no.4
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• pp.399-404
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• 2010

We propose a seamless IPTV transport technology of mobile device. This technology uses multiple interfaces of wireless communication on mobile device. This proposal for transportation of mobile IPTV contents is more mobile and adaptable than other wireless technologies that are currently being used. Algorithm of proposed technology is as follow. When the signal strength of the connected wireless network interface of mobile device is getting lower than specified level, another wireless network interface is connected to continue downloading the IPTV contents in advance. Another connection is maintained until the signal strength of the first connected interface is stable or the interface is connected to another base station (or AP) that have good signal strength. For more seamless services, we consider classifying the packets of mobile IPTV and using dynamic content quality select techniques. Dynamic content quality selection is based on notifying transfer rate to the content delivery network (CDN) server. The proposed technology is expected to use efficiently with both mobile IPTV and the transportation of mobile P2P/P4P.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.1
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• pp.27-33
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• 2012

Internet Data Centers (IDC), as essential facilities for modern IT industry, typically have scores of MW of concentrated electric loads. Uninterruptible Power Supplies (UPS) are necessary for the power feed system of IDCs because of stable power requirement. Thus, conventional AC power feed systems of IDCs have three cascaded power conversion stages such as (AC-DC), (DC-AC), and (AC-DC), which results in very low conversion efficiency. On the contrary, DC power feed systems need just a single power conversion stage (AC-DC) supplying AC mains power to DC server loads, which gives comparatively high conversion efficiency and reliability. This paper compares the efficiencies between 220V AC power feed system and 300V DC power feed system on equal load conditions which were established in Mok-Dong IDC of Korea Telecom company (KT). Experimental results show that the total operation efficiency of the 300V DC power feed system is around 15% higher than that of the 220V AC power feed system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.8B
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• pp.805-811
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• 2009

Firstly, this dissertation suggests the tag ID transfer method using two-dimensional arrangement. Secondly, provide better and stable security system compare to existing one by transferring tag; ID using established two-dimensional arrangement. Thirdly, provide operating module, which possible to descramble two-dimensional arrangement, with a character set when descrambling in a tag and a server. Lastly, suggest safe key transfer using a character set and two-dimensional arrangement. In order to embody suggested system and assess, transferred two-dimensional arrangement several times to carry out the experiment. Confirmed that it is impossible for suggested system to decode key patterns compare to existing RFID systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.7
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• pp.519-525
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• 2013

The traffic classification is a preliminary and essential step for stable network service provision and efficient network resource management. However, the payload signature-based method has a significant drawback in high-speed network environment that the processing speed is much slower than other method such as header-based and statistical methods. In this paper, We propose the server IP, Port cache-based traffic classification method using application traffic locality to improve the processing speed of traffic classification. The suggested method achieved about 10 folds improvement in processing speed and 10% improvement in completeness over the payload-based classification system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.5
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• pp.919-925
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• 2006

Mobile IPv6 generates the loss of packets and out of sequencing when hand off, In this paper, We propose a improved hand off techniques using the mobility pattern of mobile nodes. As making group by presetting the moving range of mobile nodes, and putting buffer server in the group, the packet loss and out of packet sequence can be reduced. The proposed method prevents the out of packet sequence in If level which can be happened in the stable state, minimizes the packet re-send in TCP level. In the simulation, the proposed hand off techniques transmits packets efficiently by using the mobility pattern of mobile nodes.