• 한국정보통신학회논문지
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• 제13권12호
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• pp.2563-2568
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• 2009

대칭암호시스템은 빠른 속도로 암 복호를 행하는 장점을 지니지만 안전하게 비밀키를 분배하는 방법에 문제점이 있다. 특히, 비밀통신을 원하는 불특정 사용자가 공통으로 가져야 할 비밀키를 분배하는 방안이 핵심쟁점이 되어왔다. 이러한 문제의 해결 방안으로 Diffie-Hellman 키 교환방법이 제안되었다. 하지만 이 스킴은 중간공격자(MITM, Man In TheMiddle) 공격에 취약한 것으로 판명되었다. 본 논문에서는 이러한 문제점을 해결하기 위한 하나의 방안으로 널리 사용되는 이동 전화 채널을 이용하여 강화된 Diffie-Hellman 키 교환방법을 제안하였다. 제안방안은 이동전화를 통해 교환된 인증번호와 생성된 Diffie-Hellman 키를 합성하여 송신자와 수신자에게 세션키를 분배하는 방안이다. 이렇게 함으로써 Diffie-Hellman 키 교환방법에서 쟁점이 된 중간공격자 공격을 실용적인 방법으로방어할 수 있다.

• Journal of Multimedia Information System
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• 제3권4호
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• pp.129-134
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• 2016

A routing protocol in mobile ad hoc networks is important, and a location based routing has attracted attention. We have proposed a method, in which plural mobile agents (MA) manage location information and construct a route and the number of MA dynamically changes depending on the network situation. However, the area where each MA manages is not always appropriate. This would increase the network load due to unnecessary split and mergence of MAs. To solve this problem, in this paper, we propose an enhanced method. In this method, the MA management area is properly determined based on distribution of nodes. From the performance evaluation, we show that the proposed method outperforms conventional methods in terms of packet delivery rate when network load is high.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권9호
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• pp.2173-2193
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• 2013

In order to reduce the distribution cost of sensor nodes, a mobile sensor deployment has been proposed. The mobile sensor deployment can be solved by finding the optimal layout and planning the movement of sensor nodes with minimum energy consumption. However, previous studies have not sufficiently addressed these issues with an efficient way. Therefore, we propose a new deployment approach satisfying these features, namely a tree-based approach. In the tree-based approach, we propose three matching schemes. These matching schemes match each sensor node to a vertex in a rake tree, which can be trivially transformed to the target layout. In our experiments, the tree-based approach successfully deploys the sensor nodes in the optimal layout and consumes less energy than previous works.

• 한국컴퓨터정보학회논문지
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• 제5권4호
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• pp.126-130
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• 2000

컴퓨터 환경이 집중화에서 분산화로 변화함에 따라 새로운 분야들이 나타나게 되었다. 이런 변화에서 본 논문이 다루고자하는 새로운 분야는 Jini와 이동 에이전트와 같은 기술들이다. 그러나 이 기술들은 신기술을 채용했지만 각각의 문제점들을 갖고 있어 높은 활용도를 발휘하지 못하고 있다. Jini는 서비스에 부하를 많이 준다는 점에서, 이동 에이전트는 정해진 경로만 이동하거나 새로운 경로의 추가와 제거가 쉽지 않다는 점에서 문제점을 가지고 있다. 따라서 본 논문에서는 Jini 기반의 이동 에이전트를 설계하여 동적으로 경로를 설정하고, 서비스에 부하를 덜 주면서 클라이언트에게 서비스를 제공하는 시스템을 제안한다.

• KEPCO Journal on Electric Power and Energy
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• 제2권2호
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• pp.245-251
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• 2016

Despite the exponential throughput improvement in mobile communications systems, their ability to satisfy requirements of state-of-the-art and future applications of advanced metering infrastructure (AMI) is still under investigation. Challenges are mainly due to the inadequacy of third generation partnership project (3GPP) networks to support large amounts of devices simultaneously, while the number of AMI end-devices and the frequency of their data transmission increase with new AMI-based applications. In this introductory survey, innovative and future AMI applications and their communication requirements are first reviewed. Then, we identify challenges of 3GPP long term evolution (LTE) in enabling future AMI applications. More importantly, the latest improvements to LTE-A standard release 12 and 13 are reviewed and analyzed with regards to their potential to improve the quality of LTE-enabled AMI. It is found that 3GPP enhancements on machine type communications (MTC) standards will significantly enhance AMI communications. Beyond MTC specifications, non-MTC-specific enhancements such as carrier aggregation and multi-connectivity for user equipment will also contribute greatly to improving reliability and availability of AMI devices. The paper's focus is towards improved backhaul support for innovative and future AMI applications, beyond traditional automatic meter reading.

• 제어로봇시스템학회논문지
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• 제14권12호
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• pp.1294-1301
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• 2008

Under passive RFID environment, this paper presents a new localization of a mobile robot traversing over the floor covered with tags, which is superior to existing methods in terms of estimation performance and cost effectiveness. Basically, it is assumed that a mobile robot is traveling along a series of straight line segments, each segment at a certain constant velocity, and that the number of tags sensed by a mobile robot at each sampling instant is at most one. First, for a given line segment with known starting point, the velocity and position of a mobile robot is estimated using the spatial and temporal information acquired from the traversed tag. Some discussions are made on the validity of the basic assumptions and the localization for the initial segment with unknown starting point. Second, for a given tag distribution density, the optimal tag arrangement is considered to reduce the position estimation error as well as to make easy the tag attachment on the floor. After reviewing typical tag arrangements, the pseudorandom tag arrangement is devised inspired from the Sudoku puzzle, a number placement puzzle. Third, through experiments using our passive RFID localization system, the validity and performance of the mobile robot localization proposed in this paper is demonstrated.

• 한국정보과학회논문지:정보통신
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• 제32권3호
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• pp.404-414
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• 2005

3 세대 이상의 차세대 패킷 기반 이동 통신 시스템은 패킷 네트워크의 특성 때문에 사용자가 받는 서비스의 질이 셀(Cell)의 트랙픽 부하량에 의해 직접적인 영향을 받는 구조로 되어 있다. 또 이동통신 시스템에서 트래픽 집중화 현상은 시스템 자원을 충분히 활용하지 못하면서 호(Call) 탈락률을 높여 전체 시스템 성능이 떨어지는 핫셀(Hot cell) 문제를 야기한다. 그러므로 패킷 네트워크를 기반으로 하는 이동 통신 시스템에서 자원을 효율적으로 사용하기 위해 트래픽을 분산시키는 것은 매우 중요하다. 따라서 본 논문에서는 패킷 기반의 이동 통신 시스템에서 핸드오프 시 주변 셀의 부하 정보를 고려해 몰려있는 트래픽을 주위로 분산시키는 적응적 핸드오프 알고리즘을 제안한다. 또, 패킷 네트워크에서 트래픽 부하를 측정하는 방법으로 MAC 상태도에서 트래픽 전송 및 트래픽 대기 상태에 있는 사용자의 수를 이용하는 기법도 제안한다. 그리고 모의 실험 결과를 통하여 제안하는 핸드오프 기법이 트래픽을 분산시켜 시스템 전체 측면에서의 자원을 효율성을 높이고, 사용자의 서비스 질을 보장함을 보인다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.339-340
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• 2007

This paper proposes a object avoidance algorithm that enables a mobile robot with laser scanner. Object detecting system has a function to detect object in front of the mobile robot by using a laser scanner. The proposed method based on probability distribution and finds local-paths to avoid collisions. Simulation results show the feasibility of the proposed method.

• 한국연소학회지
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• 제1권2호
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• pp.9-20
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• 1996

We construct a mobile broadband coherent anti-Stokes Raman spectroscopy system to measure the temperature of combustion gases. To improve the accuracy of CARS temperatures due to Stokes lasers, a modeless dye laser is constructed. A monochromator to disperse CARS spectra is also constructed in the spectrometer for easy portability. The accuracy of CARS temperature, measured in graphite tube furnace in reference to a radiation pyrometer, is better than 2 % from 1000 K to 2400 K. The CARS temperature error due to the variation of the spectral distribution of the modeless laser is measured to be less than 1.5 % during five hours operation. As a demonstration of combustion diagnosis, we applied the spectrometer to measure the temperature distribution of the propane air premixed flame.

• 유통과학연구
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• 제12권11호
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• pp.85-100
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• 2014

Purpose - Recently, the prevalence of high-speed mobile communication technology (4G) and mobile devices (smart phones, tablet PC, etc.) is leading innovative changes across all fields in society as well as business environments. Furthermore, a diversified mobile application service has spread rapidly through mobile devices such as smart phones and tablet PCs. Accordingly, the traditional E-government services paradigm has rapidly changed into mobile intelligence. To identify the influencing factors on the using intention of G4C smart app services, based on previous studies, the variables that influence using G4C smart app services are defined; these are user cognitive factors (perceived usefulness, perceived easiness), user characteristics factors (user innovativeness, self-efficiency, social influence), service quality factors (convenience, interactivity, accessibility), and system quality factors (instant connectivity, safety). Research design, data, and methodology - This is designed not only to collect data with a questionnaire survey (9/22/13~10/23/13) but also to test hypotheses with SEM by SPSS 21.0 and AMOS 21.0 in both Korea and China. All items are used with Likert 5 scales. A total of 643 questionnaires (Korea 318, China 325) are used. Results - The perceived usefulness and perceived easiness in user cognitive factors have positive influence on using intention. The user innovativeness, self-efficiency, and social factors in user characteristics factors have positive influences on using intention. The convenience, interactivity, and accessibility in service quality factors have positive influences on both reliability and using intention. Safety in system quality has positive influence on both reliability and using intention. Reliability has positive influence on using intention. The control variables (Korea and China) affect its control hypothesis. Strategies and implications are suggested to assist the public using the intention of smartphone's e-government services based on the results of the empirical analysis. The mobile application service can be considered a new emergence of the paradigm just like the government's on-line portal websites appeared in the past. Under this prevailing situation of mobile smart devices, to promote the success of e-government mobile APP services, accurate analysis and understanding of users should precede anything, to provide services to grasp and satisfy users' desire properly. Conclusions - This study proposes implications to help E-governmental officers and companies make strategies. First, this is expected to give some information on the understanding and knowledge regarding the process of G4C smart APP service based on the empirical study. Second, this helps to make future policies and ways about E-government G4C smart APP service. Third, it is proved that super speed mobile communication technology and devices including phones will be crucial to change the structure of E-government services in 2-3 years. Fourth, it is necessary to increase the trust and using intention of users. Fifth, considering what type of environment users are placed in, to present proper public information matching their inclination, is important. Finally, various ways of experiencing service to explore potential users and ceaseless public relations are required.