• Journal of the Korea Convergence Society
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• v.7 no.6
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• pp.43-48
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• 2016

Wireless sensor networks (WSN) can be more reliable and easier to program and use with the help of sensor database management systems (SDMS). SDMS establish a user-friendly SQL-based interface to process declarative user-defined queries over sensor readings from WSN. Typical queries in SDMS are ad-hoc snapshot queries and long-running, continuous queries. In SDMSs queries are flooded to all nodes in the sensor net, and query results are sent back from nodes that have qualified results to a base station. For query flooding to all nodes, and result flooding to the base station, a lot of communication energy consuming is required. This paper suggests an efficient in-network index solution, named Distributed Information Gathering (DIG) to process range queries in a sensor net environment that can save energy by reducing query and result flooding.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.6
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• pp.1-10
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• 2001

In this paper, we propose a synchronous reservation protocol that is efficient for supporting variable sized messages in a wavelength division multiplexing (WDM) based local network using a passive star topology. A. control channel is used to coordinate transmission on data channels. Time is slotted with fixed-sized slots. The network can accommodate a variable number of nodes, and can operate independently of the change of the number of nodes. So, any 'new' node can join the network anytime without network re-initialization. Moreover, with the protocol, we can avoid data channel and destination conflicts. We analyze the performance by using EPA method according to the variation of the end to end propagation delay with respect to one slot time, and validate the results by simulation.

• Journal of Korea Society of Industrial Information Systems
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• v.7 no.5
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• pp.175-182
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• 2002

The email system is one of the most popular internet applications used to transmit and exchange personal information. However, the pattern of existing email system is fixed, and the system cannot be expanded or re-used. This thesis has proposed the system which can provide the users with better e-mail data which is flexible, re-usable, and expandable XML data on the web-mail. The process of change is as follows: First, make the XML data to have a tree structure using DOM API and then bring the received messages of the users with the CDONTS. Last, transform the received messages into the element and element value. When the e-mail data is transformed t the XML data, 'the data' and 'the presentation' can be distinguished, which enables the users to see messages according to each individual's unique need. With this system, the user can not only convert data to XML, but also can combine the data segments to a form of letter box in order to manage data conveniently and search the data.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.414-418
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• 2003

VoIP is a core technology used to transmit both voice and data in an integrated packet' form. Within this technology, SIP is the signaling protocol used for 'real time' call services; particularly those where H323 is used. Yet, when considering the needs of mobile users, it is essential we integrate VoIp within the mobile technology so the mobile host is able to receive the 'packet' transported and by, and connected to, any available internet-address. For all this to occur, we need to improve Network Delay by reducing transmission problems associated with mobile services. If we are to obtain an optimal service then we must reduce any network delays which may arise from joining Mobile IP and VoIp services. This paper, therefore, considers how, unlike previous research, these delays may be improved through the use of the signaling technology\ulcorner SIP. It also considers how this research may be introduced into current wired and wireless integrated services enabling them to use the IP 'packet'.

• Journal of KIISE:Information Networking
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• v.30 no.2
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• pp.244-251
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• 2003

As the Internet and wireless mobile communication is being widespread, the WAP (Wireless Application Protocol) that merges these two technologies has emerged. Also, the research of the WAP gateway that enables efficient processing of multiple user demands concurrently and prompt response to requests from various wireless devices has been performed in many working groups. The WAP stack is the most fundamental technology among these researches. In this paper, we implement the WAP container utilizing the JAVA's multithreading and applying to the connection pooling technique to manage the available resource in the container efficiently. Also, we design and implement the WTP(Wireless Transaction Protocol) layer and the UDP(User Datagram Protocol) layer based on the priority Policy. Our design and implementation showed the shorter waiting time than that of the existing FCFS(First-Come, First-Served) system in the transaction layer and its efficiency was proved through simulation.

• Journal of Internet Computing and Services
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• v.6 no.5
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• pp.143-154
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• 2005

This paper presents a reliable multicast transmission for the advertising-supported Access Point in which a user can use a wireless network access service through receiving the advertisement. In this paper we propose a application-layer multicast protocol that controls a transmission rate of the mobile device for the reliable multicast in wireless LAN environment. Internet advertising includes all means and medias for advertising on the Internet in order to raise sales or popularity of the products or services. Since the current Internet advertising systems are passive, the target systems are exposed to unspecified persons and its exposure rates of the advertisement are changeable and unpredictable. In this paper, we propose an Internet advertising system, with which users can access the wireless Internet without charge, advertisers can provide customized advertisement according to location, time, and categories of users, and owners of network infrastructure can manage the system with a low cost.

• Proceedings of the Korea Contents Association Conference
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• 2004.11a
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• pp.101-109
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• 2004

Internet got into popularization by development of digitech today, and according as Internet user increases, advertisement that use internet is increasing. Specially, advertisement that use internet regardless of time customer and company both direction(interactive) communication possible because, image about special quality of product or company feature that can be active to customer and offer effectively have. There is charm that both direction communication that internet advertisement can attract to unspecified multitude internet connecter regardless of time this are available, internet user can do participation more easily. Interaction of Banner advert or different advertisement that form commentary of current internet advertisement is inert with internet posthumous work. It can become more efficient advertisement if take advantage of prognostication that most important element of game is interaction in internet advertisement. Investigator who aim in this point wishes to do on the basis of special quality of internet advertisement and interaction attribute of game and present actuality design process case of internet ad of game inclination.

• Korean Journal of Cognitive Science
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• v.12 no.4
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• pp.1-9
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• 2001

Mobile Internet can be used anytime and anyplace thanks to the portability of mobile phones and wireless connectivity to the Internet. Therefore Mobile Internet users can be in various contexts compared with Wire Internet users in stationary contexts. In this research out of various context attributes, we selected physical context attributes of hands feet and eyes and studied how these affect the performance of Internet use and user\\` satisfaction. For this research we made control1ed experiments in performing the given task in each attribute and measured the task accuracy and the subjective satisfaction. The experiments indicated that each attribute doesn\\`t affect the accuracy and satisfaction when it is given individually but when two of more context attributes are given simultaneously in context of disturbance of eyes and motion of legs the accuracy and satisfaction declines. This suggests that the subjects need more attention for the physical context of two or more factors than one factor because of the attention capacity limit. As the result, the attention capacity for the task shrinks.

• Journal of Astronomy and Space Sciences
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• v.25 no.4
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• pp.471-480
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• 2008

COMS Image Data Acquisition and Control System (IDACS) plays a key role in real time ground processing of Meteorological and Ocean observation data. Beyond processing, it serves processed image data and additional data to end users through the spacecraft in the internationally recommended format. The IDACS will be installed at three location (MSC, KOSC, and SOC) and automatically operated 24h/365days. After the IDACS subsystem tests and inter -subsystem interface tests had been completed in the first half of 2008, the acceptance test which was a comprehensive test performed as an integrated form to verify function performance and operational requirements. This paper introduces test objective, preparation, and major result of the COMS IDACS acceptance test.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.202-207
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• 2016

An auxiliary real-time train communications system among drivers, train-traffic controllers and field workers is necessary to share hazard information (i.e. rockfall detection, track maintenance) in low visibility zones (long tunnels and steep curved track). To develop the appropriate communication system, this paper proposes a new way of power line communication using the rail track (Rail - PLC), which has little noise and distortion of attenuation. Therefore, it is important to measure the impedance of the rail and to apply an impedance matching technique to increase the transmission characteristic of the Rail - PLC. This study would evaluate the reflection and the transmission characteristics of the rail using a network analyzer and an impedance matching transformer. The suitable impedance matching ratio was 1:3.28 from the result of back-to-back testing. The results confirmed that the transformer can improve the performance of the transmission signal in Rail - PLC using an impedance matching technique.