• 한국통신학회논문지
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• 제21권9호
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• pp.2385-2401
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• 1996

ATM망의 단대단 통신로 추적관리를 위한 모델과 추적 알고리즘을 제시하고 시뮬레이션을 통하여 이 알고리즘의 성능을 분석하였다. 제안 모델은 TINA(Telecommunication Information Networking Architecture)구조와 ODP(Open Distributed Processing)의 계산객체를 기본으로 하였다. 계산객체는 ATM 라우팅 기능을 수행하는 계산객체와 경로 추적을 수행하는 계산객체로 구성하였으며, 이들간의 관계를 기본으로 하는 수행절차를 설정하였다. 이 수행 절차는 연결된 ATM 경로를 추적함으로써 단대단 통신로를 식별하고 이러한 통신로 식별 데이타를 수집하는 과정으로 수행된다. 제안한 단대단 통신로 추적관리는 NML(Networking Management Level) 관점에서 수행되며, 이를 위한 알고리즘으로 실시간 속성과 추적기능의 무결성을 고려하여 broadeasting-with-synchronized-control과 GTM(Global Ticket Method)을 제안하였다.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2003년도 가을 학술발표논문집 Vol.30 No.2 (3)
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• pp.400-402
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• 2003

Ad­hoc Network는 Mobile Node들 간에 Multi­hop 무선 링크로 구성되는 Network을 일컫는 말이며, 동시에 Network를 통제하는 Infrastructure없이 Node들 간의 상호 통신에 의해서 Network이 구성되기도 하고, Node들이 이동하거나 환경적인 장애에 의해서 일시적으로 Network이 구성되지 않기도 한다. 이 논문에서는 대표적인 On­demand Routing Algorithm인 DSR를 이용하여, 두 개의 경로를 유지하여 Primary Path에 문제가 발생하는 경우, Secondary Path가 Primary Path로 전환되어 Data를 전송하고, 이 전 Primary Path에 대하여 지역적으로 복구(Repair)를 수행하고, 설정된 Secondary Path에 대해서도 특정한 조건에서 복구작업을 수행함으로써 Ad­hoc Network에서 경로를 찾고 설정하는데 필요한 Routing Overhead를 줄이고 Ad­hoc Network의 특성상 반드시 보완하여야 하는 전송 Route에 대한 Robustness를 강화하는 방법이다.

• 디지털산업정보학회논문지
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• 제10권3호
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• pp.197-205
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• 2014

In applications of adaptive noise control or active noise control, the presence of a transfer function in the secondary path following the adaptive controller and the error path, been shown to generally degrade the performance of the Least Mean Square (LMS) algorithm. Thus, the convergence rate is lowered, the residual power is increased, and the algorithm can become unstable. In general, in order to solve these problems, the filtered-x LMS (FX-LMS) type algorithms can be used. But these algorithms have slow convergence speed and weakness in the environment that the secondary path and error path are varied. Therefore, I present the new algorithm called the "Bi-directional Filtered-x (BFX) LMS" algorithm with nearly equal computation complexity. Through experimental study, the proposed BFX-LMS algorithm has better convergence speed and better performance than the conventional FX-LMS algorithm, especially when the secondary path or error path is varied and the impulsive disturbance is flow in.

• 로봇학회논문지
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• 제6권3호
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• pp.255-262
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• 2011

Many intelligent robots have to be given environmental information to perform tasks. In this paper an intelligent robot, that is, a cleaning robot used a sensor fusing method of two sensors: LRF and StarGazer, and then was able to obtain the information. Throughout wall following using laser displacement sensor, LRF, the working area is built during the robot turn one cycle around the area. After the process of wall following, a path planning which is able to execute the work effectively is established using flow network algorithm. This paper describes an algorithm for minimal turning complete coverage path planning for intelligent robots. This algorithm divides the whole working area by cellular decomposition, and then provides the path planning among the cells employing flow networks. It also provides specific path planning inside each cell guaranteeing the minimal turning of the robots. The proposed algorithm is applied to two different working areas, and verified that it is an optimal path planning method.

• Journal of information and communication convergence engineering
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• 제5권3호
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• pp.239-244
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• 2007

In the telematics system, a reasonable path search time should be guaranteed from a great number of user's queries, even though the optimal path with minimized travel time might be continuously changed by the traffic flows. Thus, the path search method should consider traffic flows of the roads and the search time as well. However, the existing path search methods are not able to cope efficiently with the change of the traffic flows and to search rapidly paths simultaneously. This paper proposes a new path search method for fast computation. It also reflects the traffic flows efficiently. Especially, in order to simplify the computation of variable heuristic values, it employs a simplification method for estimating values of traffic-adaptable heuristics. The experiments are carried out with the $A^*$ algorithm and the proposed method in terms of the execution time, the number of node accesses and the accuracy. The results obtained from the experiments show that the method achieves very fast execution time and the reasonable accuracy as well.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.2846-2848
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• 2000

In this paper we propose a path planning method for an autonomous mobile robot based on genetic algorithms(GAs). There have been a number of methods proposed for the path planning of a mobile robot. However, few algorithms have been developed for an on-line path planning of a mobile robot with the uncertain information of a task environment. Therefore, we propose a path planning algorithms based on GAs that has ability of creating path planning without the perfect information of a task environment and an ability of planning the efficient path by on-line process. Then we show a possibility of the practical use with the results of simulations and experiments.

• ETRI Journal
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• 제33권2호
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• pp.283-286
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• 2011

Path loss plays fundamental roles in system design, spectrum management, and performance evaluation. The traditional path loss model has a slight inconvenience; it depends on the unknown distance. In this letter, we explore the probability distribution function (PDF) of path loss in an indoor office environment by randomizing out the distance variable. It is shown that the resulting PDF is not Gaussian-like but is skewed to the right, and both the PDF and the moments are related to the size of the office instead of the unknown distance. To be specific, we incorporate the IEEE 802.15.4a channel parameters into our model and tabulate the cumulative distribution function with respect to different room sizes. Through a simple example, we show how our model helps a cognitive spectrum user to infer path loss information of primary users without necessarily knowing their transmitter-receiver distance.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2007년도 춘계종합학술대회
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• pp.113-116
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• 2007

본 논문은 웹기반 게임 컨텐츠로써의 3차원 최적 미로 게임 개발에 대한 논문이다. 웹을 이용한 클라이언트 접속자는 자바 애플릿을 이용하여 웹상에서 접근 가능하고 Java Bytecode의 다운로드에 의해 각 클라이언트 접속자의 하드웨어시스템에 무관하게 작동가능하다. 본 논문에서 개발된 최적 미로 게임은 랜덤 미로 생성기, 미로 내 경로 입력기, 가중 최적 경로 탐색기, 및 비교기 등으로 구성되어 있다. 최적 미로 탐색알고리즘으로 탐색된 경로와 사용자가 선택한 경로의 cost 비교를 통하여 사용자의 공간적 인지력을 정량적으로 평가 및 도시함으로써 사용자의 공간적 인지력 향상을 유도할 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권3호
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• pp.490-508
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• 2013

One of the most important scalability issues facing the current Internet is the rapidly increasing rate of BGP updates (BGP churn), to which route flap and path exploration are the two major contributors. Current countermeasures would either cause severe reachability loss or delay BGP convergence, and are becoming less attractive for the rising concern about routing convergence as the prevalence of Internet-based real time applications. Based on the observation that highly active prefixes usually repeatedly explore very few as-paths during path exploration, we propose a router-level mechanism, Path Exploration Aggregation (PEA), to scale BGP without either causing prefix unreachable or slowing routing convergence. PEA performs aggregation on the transient paths explored by a highly active prefix, and propagates the aggregated path instead to reduce the updates caused by as-path changes. Moreover, in order to avoid the use of unstable routes, PEA purposely prolongs the aggregated path via as-path prepending to make it less preferred in the perspective of downstream routers. With the BGP traces obtained from RouteViews and RIPE-RIS projects, PEA can reduce BGP updates by up to 63.1%, shorten path exploration duration by up to 53.3%, and accelerate the convergence 7.39 seconds on average per routing event.

• 한국통신학회논문지
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• 제29권12C호
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• pp.1722-1728
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• 2004

다수의 인증 경로가 존재하는 PKI 구조에서 인증 경로를 설정하는 것은 중요한 문제이다. 경로 설정은 다양한 검증을 통해 이루어지고 검증이 많을수록 경로의 유효성은 높아진다. 유효성 높은 경로의 선택은 경로 설정 및 검증 작업의 반복 횟수를 감소시킴으로서 고속의 인증서 검증이 가능하도록 하는 반면에 하나의 경로를 설정하는데 소요되는 시간 및 부담을 증가시킨다는 문제점을 가진다. 본 논문에서는 보다 적은 부합으로 경로의 유효성을 높일 수 있는 효율적인 인증 경로 설정 알고리즘을 제안한다.