• KIPS Transactions on Computer and Communication Systems
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• v.7 no.12
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• pp.301-312
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• 2018

In industrial wireless sensor networks, the continuous object detection such as fire or toxic gas detection is one of major applications. A continuous object occurs at a specific point and then diffuses over a wide area. Therefore, many studies have focused on accurately detecting a continuous object and delivering data to a static sink with an energy-efficient way. Recently, some applications such as fire suppression require mobile sinks to provide real-time response. However, the sink mobility support in continuous object detection brings challenging issues. The existing approaches supporting sink mobility are designed for individual object detection, so they establish one-to-one communication between a source and a mobile sink for location update. But these approaches are not appropriate for a continuous object detection since a mobile sink should establish one-to-many communication with all sources. The one-to-many communication increases energy consumption and thus shortens the network lifetime. In this paper, we propose the origin-centric communication scheme to support sink mobility in a continuous object detection. Simulation results verify that the proposed scheme surpasses all the other work in terms of energy consumption.

• Journal of the Korea Society of Computer and Information
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• v.16 no.12
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• pp.227-234
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• 2011

Many technologies for wireless internet are increasing as more and more laptop computers, net books, smart phone and other terminals, which provide wireless network, are created. IEEE 802.11 is computer wireless network technology that used in small area, called wireless LAN or Wi-Fi. IEEE 802.11 is a set of standards for implementing wireless local area network (WLAN) computer communication in the 2.4, 3.6 and 5 GHz frequency bands. They are created and maintained by the IEEE LAN/MAN Standards Committee (IEEE 802). AP (Access Point) is installed at cafes and public places providing wireless environment. It is more convenient to use wireless internet, however, It can be seen easily around us and possible to communicate with AP. IEEE 802.11 has many vulnerability, such as packet manipulation and information disclosure, so we should pay more attention when using IEEE 802.11. Therefore this paper developing monitoring system which can find out AP and Stations that connect with it, and capturing AP's information to find out vulnerability. This paper suggests monitoring system which traffic analysis in wireless environment.

• The Journal of Society for e-Business Studies
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• v.18 no.1
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• pp.107-127
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• 2013

The evolution of IT facilitated the communication and knowledge sharing between the social network service (SNS) users. When the more information about SNS users had been posted in SNS site, SNS users had sometimes exposed in the risk of privacy invasion. To remedy this problem, we had introduced the information control mechanisms from the prior studies in data management to the SNS area and empirically validated the effect of these mechanisms in this research. Three information control mechanisms had been elected as access control, reference control and diffusion control. We had conducted a survey to the Facebook users which is the most famous SNS site. 459 data had been gathered and analyzed by PLS algorism. As the results, reference control and diffusion control has significantly increased the trust on SNS providers and decrease the privacy concern. This change could significantly affect on the satisfaction with the SNS site and knowledge sharing intention of SNS users. This study could introduce the new perspective about privacy protection issues in SNS area. Also, the information control mechanisms suggested in this study could contribute to make more robust privacy protection mechanisms in SNS site in practice.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.522-525
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• 2018

In this paper, we design a UWB / WAS microstrip antenna for wireless local high - speed communication. The substrate of the proposed antenna is FR-4 (er = 4.3) and its size is $30[mm]{\times}30[mm]$. It is designed to have characteristics that can be used in the frequency bands of 3.5 [GHz] and 5.2 [GHz], which are UWB / WAS frequency bands. The simulation was performed using CST Microwave Studio 2014. Simulation results show that the gain is 1.592 [dBi] at 3.5 [GHz] and 2.210 [dBi] at 5.2 [GHz]. The S-parameter also showed a result of less than -10 [dB] (WSWR 2: 1) in the desired frequency band. Microstrip antennas have been miniaturized, high performance, and light weight, and excellent and low cost systems are continuously being developed. In addition, many people use wireless local area network systems used in homes, companies, and public facilities. Since the UWB / WAS technology is proposed according to the development of the system and the demand increase, the antenna that satisfies the above conditions will be designed and the technology applicable to the system will be used more conveniently.

• Journal of KIISE:Information Networking
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• v.29 no.3
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• pp.253-264
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• 2002

Recently, hierarchical architectures of databases for location management have been proposed in order to accommodate the increase in user population in future personal communication systems. In particular, a 3-level hierarchical database architecture is compatible with current cellular mobile systems. In the architecture, a newly developed additional databases, regional location database(RLR), are positioned between HLR and VLRs. We propose an efficient cache scheme, called the Double T-thresholds Location Cache Scheme. The cache scheme extends the existing T-threshold location cache scheme which is competent only under 2-level architecture of location databases currently adopted by IS-41 and GSM. The idea behind our scheme is to use two pieces of cache information, VLR and RLR serving called portables. The two pieces are required in order to exploit root only locality of registration area(RA) but also locality of regional registration area(RRA) which is the wide area covered by RLR. We also use two threshold values in order to determine whether the two pieces are obsolete. In order to model the RRA residence time, the branching Eralng-$\infty$ distribution is introduced. Our minute cost analysis shows that the double T-threshold location cache scheme yields significant reduction of network and database costs for molt patterns of portables.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.1
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• pp.35-40
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• 2011

In this paper, we compare and analyze data aggregation methods based on event area in wireless sensor networks. Data aggregation methods consist of two methods: the direct transmission method and the aggregation node method. The direct aggregation method has some problems that are data redundancy and increasing network traffic as all nodes transmit own data to neighbor nodes regardless of same data. On the other hand the aggregation node method which aggregate neighbor's data can prevent the data redundancy and reduce the data. This method is based on location of nodes. This means that the aggregation node can be selected the nearest node from a sink or the centered node of event area. So, we describe the benefits of data aggregation methods that make up for the weak points of direct data dissemination of sensor nodes. We measure energy consumption of the existing ways on data aggregation selection by increasing event area. To achieve this, we calculated the distance between an event node and the aggregation node and the distance between the aggregation node and a sink node. And we defined the equations for distance. Using these equations with energy model for sensor networks, we could find the energy consumption of each method.

• The KIPS Transactions:PartC
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• v.17C no.3
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• pp.271-280
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• 2010

For the next generation mobile communication system, diverse wireless network techniques such as beyond 3G LTE, WiMAX/WiBro, and next generation WLAN etc. are proceeding to the form integrated into the All-IP core network. According to this development, Beyond 3G integrated into heterogeneous wireless access technologies must support the vertical handover and network to be used of several radio networks. However, unified management of each network is demanded since it is individually serviced. Therefore, in order to solve this problem this study is introducing the theory of Common Radio Resource Management (CRRM) based on Generic Link Layer (GLL). This study designs the structure and functions to support the vertical handover and propose the vertical handover algorithm of which policy-based and MCDM are composed between LTE and WLAN systems using GLL. Finally, simulation results are presented to show the improved performance over the data throughput, handover success rate, the system service cost and handover attempt number.

• Journal of the Economic Geographical Society of Korea
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• v.17 no.4
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• pp.718-742
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• 2014

The capitalist economic process of glocalization and development of transportation and communication technology have led us to the significance of network city as well as concepts of global city, megacity region, etc. Network city theory pursues development of both individual cities and of the region of those cities through strengthening of mutual connectivity among them with specialized industries. On the basis of network city theory, this paper is to analyze specialized industries of cities and connectivity among them in the Youngnam region in S. Korea. It uses the methods of locational quotient, locational Gini coefficient, and shift-share method to analyze specialized industries of cities, and correspondence analysis, global and local Moran's I to examine connectivity among cities. As results, it can be identified that each city in the Youngnam region has its own specialized industries different from each others, but it seems not easy to grasp the overall extent of connectivity among them, partly because of the limitations of applied analysis methods and partly because of a lack of connectivity among cities themselves.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.3
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• pp.679-691
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• 2016

As vehicle started to contain many different communication devices, collecting external information became possible in IoT environment. In such environment, remotely controling vehicle is possible when vehicle information is obtained by looking in to vehicle network through smart device. However, android based smart device applications are vulnerable to malicious modulation and redistribution. Modulated android application can lead to vehicle information disclosure that could bring about vehicle control accident which becomes threat to drivers. furthermore, since vehicles today does not contain security methods to protect it, they are very vulnerable to security threats which can cause serious damage to users and properties. In this paper, many different vehicle management android applications that are sold in Google Play has been analyzed. With this information, possible threats that could happen in vehicle management applications are being analysed to prove the risks. the experiment is done on actual vehicle to prove the risks. Also, access control method to protect the vehicle against malicious actions that could happen through external network in IoT environment is suggested in the paper.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.5
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• pp.1311-1321
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• 2010

Sensor network is used to obtain sensing data in various area. The interval to sense the events depends on the type of target application and the amounts of data generated by sensor nodes are not constant. Many applications exploit long sensing interval to enhance the life time of network but there are specific applications that requires very short interval to obtain fine-grained, high-precision sensing data. If the number of nodes in the network is increased and the interval to sense data is shortened, the amounts of generated data are greatly increased and this leads to increased amount of packets to transfer to the network. To transfer large amount of packets fast, it is necessary that the delay between successive packet transmissions should be minimized as possible. In this paper, we propose SET(SendDoneEventbasedTransmission Technique)which reduces the delay between successive packet transmissions by using SendDone Event which informs that a packet transmission has been completed. In SET, the delay between successive packet transmissions is shortened very much since the transmission of next packet starts at the time when the transmission of previous packet has completed, irrespective of the transmission time. Therefore SET could provide high packet transmission rate given large amount of packets.