• Journal of the Korea Society of Computer and Information
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• v.16 no.7
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• pp.165-172
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• 2011

This study was to investigate which factors promote the usage of WiBro service, and to propose a few of research propositions on the relationships between these factor and characteristics of mobile Internet usage. To accomplish these research purposes, the study defined research variables such as factors promoting the usage of WiBro service, characteristic of mobile Internet usage, and types of user based on the review of mobile Internet service related studies. The study performed various statistical analyses using survey questionnaires on mobile Internet users, and finally proposed some research propositions, based on the analysis results, that could be used in the future studies.

• Journal of the Korea Society of Computer and Information
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• v.17 no.12
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• pp.131-136
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• 2012

In these days, with the diffusion of mobile equipments, the number of WiFi Access Point (AP) is increasing, and the growth of WiFi AP causes the throughput degradation due to interferences between APs. This recent phenomenon demands the method able to be utilized with current WiFi network to improve the throughput of Wireless LANs. This paper studied the channel assignment method and several throughput enhancement methods to optimize Radio Resource Management (RRM) for distributed infrastructure WLANs. As a result, it was able to put AP independently, improve older allocation error, and improve execution speed.

• Proceedings of the Korean Society of Computer Information Conference
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• 2011.06a
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• pp.95-99
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• 2011

최근 무료 WiFi Zone이 확대되고 있고, Smart Phone으로 무료 WiFi에 접속하여 인터넷으로 접속하여 메신저를 하거나, 메일확인, 정보검색 등을 한다. 하지만 무료 WiFi Zone에서 Smart Phone으로 인터넷을 할 때, 개인정보를 해킹 당 할 수가 있다. 본 논문에서 안드로이드 O,S, Smart Phone에서 무료 WiFi를 이용하여 접속한다. 먼저 메신저와 웹사이트 로그인을 한다. 이때 AirPcap을 이용하여 패킷을 캡처한다. Packet 분석 툴인 WireShark를 사용하여 Packet의 내용을 분석하고, ID, PW와 메신저 대화 내용을 해킹한다. 해킹한 개인정보 ID, 비밀번호를 이용하여 인터넷 사이트에 접속을 하여 관리자 권한을 획득한다. 그리고 Smart Phone에서 WiFi접속 시 공격에 대한 보안대책을 제시한다. 본 연구는 Smart Phone에서 무료 WiFi 접속 때, 보안성 강화연구와 무선 해킹과 방어 기술 발전에 초석이 될 것이다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.363-364
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• 2015

On the area which is restricted an unauthorized WiFi service, mobile WiFi hotspot causes security problems like leaking and gathering internal data. In this paper, we modify a wireless lan driver and implement a detector that periodically scans the wireless channels.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.7A
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• pp.659-665
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• 2006

When using the Mobile IP which is the representative technology to secure the mobility in general IP networks, the packet loss during the handover is inescapable. To remedy the packet loss problem, the smooth handover was introduced. However, the smooth handover causes the packets sequence disruption during the packet forwarding procedure and it may result in the degradation of the network performance. The same problem also occurs in the WiBro (High-speed Portable Internet) system that is the next generation portable IP service system. The WiBro system, which provides the high speed data service just like xDSL and leased line in wired internet, aims to guarantee the portability, mobility, and the differentiated service based on IEEE 802.16. So, the handover mechanisms that solve the problems of packet loss and packet sequence distribution are required in the WiBro system. In this paper, we propose the handover mechanism and the packet sequence control algorithm that provide the reliability and the differentiated service for the unicast service in the WiBro system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.12
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• pp.3020-3028
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• 2014

In the present study, A protocol gateway between agent is designed by using an optimized protocol for the exchange of ISO / IEEE 11073-20601 in order to compensate the disadvantage of the existing gateway and a international standard healthcare set-top. The gate way was designed to smooth data transmission to overcoming the geographical limits of the service and to enable data transfer on emergency vehicle and the mountain area.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5B
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• pp.264-273
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• 2005

Nowadays the integration of heterogeneous wireless networks become a hot issue in communications research area. Especiall,y, 3G and WiBro interworking will be introduced soon as users can be offered the most suitable service according to service area and service providers can reduce network construction and operation expenses. In this paper, we propose an interworking scheme for fast handoff between 3G and WiBro networks. The SCI (Smoothly Coupled Integration) scheme proposed in this paper takes advantages of the existing LCI (Loosely Coupled Integration) and TCI (Tightly Coupled Integration) scheme and can offer seamless services by providing fast handoff between 3G and WiBro although each network may work independently. Through extensive computer simulations using OPNET, the efficiency of the proposed scheme has been validated.

• Journal of the Korea Society of Computer and Information
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• v.13 no.7
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• pp.181-188
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• 2008

Nowadays, WiMAX which provides internet service with a middle and low speed serves more function and is wider than Wi-Fi. While they solve the security risks as subscribers do handover by subscriber's re-certification procedure as the Network range is getting wider, there are more security problems making the problems of electric-power consumption and delay. This paper suggests a handover mechanism which simplify the subscriber's re-certification procedure and prevents a security problem as doing handover for solving the problem of delay and the rate of processing. The mechanism can cooperate with PKI structure to increase flexibility and security and minimize network re-entry procedure or re-certification procedure by providing continual service. As a result. the mechanism's throughput as the number of subscribers is lower than IEEE 802.16e and the mechanism proves that it is secure from the attack of man-in-the-middle and reply as doing handover.

• Land and Housing Review
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• v.12 no.4
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• pp.1-13
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• 2021

This study investigates the effectiveness of Jeju's public Wi-Fi policy for which the key factors of public Wi-Fi use and location characteristics are analyzed. Spatial regression analysis was conducted within a 100 m radius of public Wi-Fi access points. In the analysis, the dependent variable was public Wi-Fi usage time while independent variables included demographic factors, location factors, and other factors. The findings reveal that demographic factors such as the number of residents, the number of workers, and the number of visitors had a close correlation with the use of public Wi-Fi. In addition, the number of bus stops and land prices of each parcel, land use mix, and AP installation period had a positive correlation with the use of public Wi-Fi. On the contrary, the number of buildings by use, the total floor area of buildings, and the number of tourist attractions had negative correlations with public Wi-Fi usage time. These findings provide policy implications that more active publicity on Jeju's public Wi-Fi is needed and the convenience for access needs to be improved.

• The Korean Journal of Ecology
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• v.4 no.3_4
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• pp.59-67
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• 1981

Stomatal resistances of the leaves in Heteromeres arbutifolia and of the stems in Ferocactus acanthodes were studied to estimate active and passive behaviors of the guard cells on a theoretical basis. Active and passive stomatal responses to light and water deficit were observed. When the change rate of existent water due to variation of osmotic potential in the guard cells and the loss rate of transpirational water from the guard cells are $\Delta$wi-$\Delta$wt and leaded to active behaviors for opening and closing stomata. However, when stems of F. acanthodes with stomata closecd under the solar irradiation were covered with black cloth and then taken off, behaviors of the guard cells occurred in the condition of $\Delta$wi<$\Delta$wt and were passive. Under the conditiion of $\Delta$wi<$\Delta$wt due to cutout from stems, passive behaviors of the guard cells in H. arbutifolia and F. acanthodes always occurred in spite of the solar irradiation and darkness, respectively. The transpirational resistance coefficients of the guard cells in stems of F. acanthodes (0.380) and Opuntia bigelovii (0.135) wer emuch higher than in leaves of H. arbutifolia (0.034). Moreover, stomatal opening in stems of F. acanthodes during the daytime could be induced by watering. Those results are interpreted as that since the guard cells in desert Crassulacean acid metabolism (CAM) plants always exist in the state of stomatal opening, nocturnal stomatal opening and daytime stomatal closing are exhibited by passive behaviors of the guard cells in the alternant conditioins of $\Delta$wi>$\Delta$wt and $\Delta$wi<$\Delta$wt, respectively.