• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.876-877
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• 2014

In recently, the SNS which is the hot issue of the knowledge-based information age use various goal based on human networking. This service construct a human relationship which exchange of information and opinion freely, and can extend the human network relationship using open his profile and closeness others. But, each individual's privacy invasions and pissing based on information open and sharing are rising. In this paper we present a method of protecting the SNS group's communications and information interchangeability efficiently.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.05a
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• pp.435-438
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• 2008

한전에서는 연간 전력 사용량이 높은 고압 고객에 대하여 전자식 전력량계를 설치하여 15분 단위로 전력 사용량을 수집하는 자동검침시스템을 운영하고 있다. 본 연구에서는 자동검침시스템을 통해 수집된 데이터를 이용하여 배전선로에 대한 부하를 분석하기 위해 자동검침 고객의 부하 데이터를 이용하여 클러스터링 기법을 통해 대표 부하패턴을 생성하는 방식을 제안하였다. 기존에는 계약종별 코드가 동일한 고객들의 부하패턴을 이용하여 15분 단위의 평균 사용량을 계산하여 대표 부하패턴을 생성하는 방식을 사용하였으나, 같은 계약종별 코드를 갖는 고객이라 할지라도 부하패턴이 다른 경우가 많아서 부하분석의 정확도를 떨어뜨렸다. 본 연구에서는 동일한 계약종별 코드를 갖는 고객에 대하여 15분 단위 자동검침 데이터를 이용하여 k-means 기법을 통해 고객을 분류하고 각 그룹마다 대표 부하패턴을 생성하는 방식을 제안하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.3
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• pp.151-156
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• 2013

Android that was made by Google and Open Handset Alliance is the open source software toolkit for mobile phone. In a few years, Android will be used by millions of Android mobile phones and other mobile devices, and become the main platform for application developers. In this paper, the integrated login application based on Google's Android platform is developed. The main features of the mobile combination login application content based on Android are as follows. First, the application has more convenient login functionality than the functionality of general web browser as the web browser of the mobile-based applications(web browser style applications) as well as security features and faster screen(view) capability by reducing the amount of data transfer. Second, the application is so useful for management of ID and Password, and it can easily manage multiple ID information such as message, mail, profile. The results of performance evaluation of the developed application show the functionality that can login many kinds of portal sites simultaneously as well as the ability that can maintain login continuously. Currently, we are trying to develope a couple of the technologies that can insert multiple accounts into one ID and check all information on one screen.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.1A
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• pp.19-27
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• 2011

WiBro is a wireless mobile communication system which supports a high data rate and high mobility in anywhere and anytime. Although WiBro system provides multimedia service including data, audio and video services, customers require better service quality in WiBro system. But, many researches have theoretically evaluated the performance of WiBro system without systematic studies by simulation. Therefore, in this paper, we evaluate a performance of WiBro system using OPNET simulator. We analyze system performance according to various modulation and coding schemes, and propose Adaptive Modulation and Coding (AMC) profile to support quality of services for user requirements. Also we evaluate the performance of WiBro system using AMC and Hybrid-Automatic Repeat Request (H-ARQ) technologies, and confirm that the proposed AMC profile can be applied to WiBro system with high performance.

• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.10-15
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• 2007

Small size and low profile antenna for mobile vehicular-top-mounted is needed in satellite communication services such as DBS, Satellite Internet and VSAT. In middle latitudes, the development of an array antenna which has the conformal, low profile and 45 degree beam tilted configuration, and has the high gain with sharp beamwidth, low sidelobe and low loss is required for Ku-band satellite communication. In this paper, in order to meet with these performances, an array antenna consisting of the vertical polarized waveguide longitudinal slots based on the leaky-wave mode of traveling wave antenna is proposed. An array antenna consisting of 16 leaky-wave elements is showing 30 dBi of gain, 4.9 degree of beamwidth, below than -20 dB of sidelobe level, 45 degree of beam tilt angle in center frequency. Feed network designed by waveguide cooperated feed shows good performance of wideband and low loss.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7C
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• pp.985-996
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• 2004

In order to solve the increasing security problems, IDSs(Intrusion Detection System) have appeared. However, local IDSs have a limit to detect various intrusions in a large-scale network environment. So there are a lot of researches in progress which organize the elements of IDS in a distributed or hierarchical manner. In this paper, we design a integrated IDS which exchanges messages between them through the standardized message format (IDMEF) and communication protocol (IDXP). We also propose a policy profile for an effective control of IDSs, and employ the PKI mechanism for mutual authentication. We implement a prototype system for the proposed IDSs communicating with Snort and analyze its performance.

• The Journal of the Convergence on Culture Technology
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• v.6 no.3
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• pp.419-425
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• 2020

In this paper, when a refractive index grating and a gain grating are simultaneously present in a DFB (Distributed Feedback) laser for a 1.55 um wavelength with two mirror surfaces without an anti-reflective coating, an analysis program was developed to determine the beam distribution of the oscillation mode in the longitudinal direction. As the phases of the index and gain gratings on the mirror faces are varied, the lasing gain and the beam profiles |R(z)| and |S(z)| of the lasing mode with the emitted power ratio P_l/P_r are analyzed and examined in case of δL<0. In order to reduce the threshold current of a oscillation mode and enhance the frequency stability, κL should be greater than 8, regardless of the grating phase values at the mirror surface.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.9B
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• pp.847-856
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• 2009

In geographic routing for wireless sensor networks, sources need the location of sinks destined for delivering their data packets. Most of the existing geographic routing protocols merely assume that the sources can get the locations of sinks by some location service. How source nodes find out the location of sinks is not easy. In this paper, we propose a sink location dissemination scheme in geographic routing for wireless sensor networks. In this scheme, a source node and a sink node send sink location announcement and query messages along two paths respectively by geographic routing. The node located on the crossing point of the two paths informs the source about the sink location. Then the source can send data packet to the sink by geographic routing. How to guarantee that these two paths have at least one crossing point in any irregular profile of sensor network is the challenge of this paper Simulation results show that our protocol is significantly superior to other protocols in terms of energy consumption and control overhead.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3A
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• pp.240-248
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• 2006

In this paper, we consider an OFDM receiver algorithm design for IEEE 802.11a/p system, which targeting large coverage area while keeping the transmission format unchanged. Particularly, taking into account the inter-symbol interference(ISI) and inter-carrier interference(ICI) that can be induced with large RMS delay spread, we employ channel shortening time-domain equalizer(TEQ) and evaluate the receiver performance in terms of SINR and packet error rate(PER). The preamble defined in IEEE802.11a/p is used to estimated the initial equalizer tap coefficients. Primary purpose of the paper is to give an answer to the question, though partially, whether or not 16-QAM constellation can be used in none line of sight environment at the boundary of a large coverage area. To this end, we first analyze the required TEQ parameters for the target channel environment and then perform simulation for PER performance evaluation in a generic frequency selective fading channel with exponential power-delay profile.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.2 no.2
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• pp.69-77
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• 2009

Small size and low profile antenna for mobile vehicular-top-mounted is needed in satellite communication services such as DBS, Satellite Internet and VSAT. In middle latitudes, the development of an array antenna which has the conformal, low profile and 45 degree beam tilted configuration, and has the high gain with sharp beamwidth, low sidelobe and low loss is required for Ka band satellite communication. In this paper, in order to meet with these performances, an array antenna consisting of the vertical polarized waveguide longitudinal slots based on the leaky-wave mode of traveling wave antenna is proposed. Especially, for the lower sidelobe level the radiation power control using a design method of the different slot width is proposed. An array antenna consisting of 32 leakywave elements is showing 34.4 dBi of gain, 3.6 degree of beamwidth, below than -25 dB of sidelobe level, 43 degree of beam tilt angle in center frequency 20.0 GHz. Feed network designed by waveguide cooperated feed shows good performance of wideband and low loss.