• 인터넷정보학회논문지
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• 제22권5호
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• pp.9-16
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• 2021

Recently, the traffic volume of mobile communications increases rapidly and the small-cell is one of the solutions using two offload schemes, i.e., local IP access (LIPA) and selected IP traffic offload (SIPTO), to reduce the end-to-end delay and amount of mobile data traffic in the core network (CN). However, 3GPP describes the concept of LIPA and SIPTO and there is no decision algorithm to decide the path from source nodes (SNs) to destination nodes (DNs). Therefore, this paper proposes a dynamic mobile data traffic offload scheme using small-cells to decide the path based on the SN and DN, i.e., macro user equipment, small-cell user equipment (SUE), and multimedia server, and type of the mobile data traffic for the real-time and non-real-time. Through analytical models, it is shown that the proposed offload scheme outperforms the conventional small-cell network in terms of the delay of end-to-end mobile data communications and probability of the mobile data traffic in the CN for the heterogeneous networks.

• 산업경영시스템학회지
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• 제20권41호
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• pp.103-112
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• 1997

In this paper, a nonhierarchial integrated information network with circuit switched and packet switched traffic is considered. It is assumed that circuit switched traffic is allowed to attempt an alternate path if the direct path is blocked, whereas packet switched traffic is not. The network uses a movable boundary scheme to allocate bandwidth dynamically. To analyze the performance of this type of network, EEBP(End to End Blocking Probability) is selected as a measure for circuit switched traffic and average time delay for packet switched traffic, respectively. EEBP and average time delay are derived analytically. Using the two proposed measure, the performance of the network under various bandwidth allocations and arrival patterns are observed. Moreover, the arrival rate of one link for circuit switched traffic is obtained from an approximation formula. Simulation results reveal the validity of the proposed approximation method.

• 해양환경안전학회지
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• 제23권1호
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• pp.9-16
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• 2017

우리나라 주요 항만의 입출항 통항패턴을 연구하기 위한 사전 연구로서, 부산항에 입 출항하는 위험화물운반선의 통항량을 항만운영정보시스템(Port Management Information Systim, Port-MIS) 자료를 이용하여 사전 조사하고, 통항량이 가장 높은 각 계절별 연속 3일을 선별하였다. 해양안전종합정보시스템(General Information Center on Maritime Safety & Security, GICOMS) 자료를 이용하여 선별된 12일간 위험화물운반선의 부산항 주요 통항로의 통항 패턴을 분석하였다. 또한 주요 입출항 지점인 북항 오륙도 방파제와 감천항 동방파제의 위험 화물운반선의 통항 이격거리를 분석하였다. 항로 단면에서 선박의 궤적이 정규분포를 이룬다는 가정을 근거로 해상교통안전진단 등에서 정규분포의 누적 확률분포 함수를 이용하여 충돌확률을 추정하여 사용하고 있지만, 오륙도 방파제 입출항 및 감천항 동방파제 입항에서의 선박의 항해 궤적은 KS-test 및 SW-test를 이용한 정규성 검정결과 정규분포를 따르지 않는 것으로 평가되었다. 특히 북항에서는 선박의 우측통항 경향이 두드러지게 나타났다. 일반적인 통항이론의 적용보다는 항만의 특성에 맞는 통항모델을 개발하여, 해상교통안전진단 등에서 적용하는 것이 바람직하여 이에 대한 후속연구가 필요할 것으로 판단된다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권10호
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• pp.2587-2600
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• 2012

It has been demonstrated that choosing an appropriate relay node can improve the transmission rate for the system. However, such system improvement brought by the relay selection may be degraded with the presence of the malicious relay nodes, which are selected but refuse to cooperate for transmissions deliberately. In this paper, we formulate the relay selection issue as a restless bandit problem with the objective to maximize the average rate, while considering the credibility of each relay node, which may be different at each time instant. Then the optimization problem is solved by using the priority-index heuristic method effectively. Furthermore, a low complexity algorithm is offered in order to facilitate the practical implementations. Simulation results are conducted to demonstrate the effectiveness of the proposed trust-based relay selection scheme.

• 한국정보처리학회논문지
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• 제6권4호
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• pp.977-987
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• 1999

현행 교통 신호 제어기는 사전에 계획된 신호 시간 체계 또는 시간대별로 선택되는 방법을 취하고 있다. 이와 같은 신호 체계는 교통 상황 변화에 적절하게 대응하기 어려운 문제점을 갖고 있다. 특히, 혼잡 상황과 같은 문제들은 이진 논리로써 해결하기 어렵다. 따라서, 본 논문에서는 교통 혼잡 상황에 신속하게 대처할 수 있는 신호기 제어 시스템을 제안하였다. 본 논문에서 제안한 제어기는 불확실성 및 퍼지환경에서 작동한다. 따라서, 도로의 혼잡 상황을 퍼지 논리를 사용하여 표현하고 퍼지 추론기에 의해 신호 시간을 결정하도록 하였다. 본 논문에서 제안한 신호기 제어 시스템의 타당성을 검증하고자 페트리네트를 이용하여 모델링 하였다.

• 제어로봇시스템학회논문지
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• 제22권2호
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• pp.110-116
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• 2016

Autonomous vehicles must obey the traffic laws in order to drive actual roads. Traffic signs erected at the side of roads explain the road traffic information or regulations. Therefore, traffic sign recognition is necessary for the autonomous vehicles. In this paper, color characteristics are first considered to detect traffic sign candidates. Subsequently, we establish HOG (Histogram of Oriented Gradients) features from the detected candidate and recognize the traffic sign through a SVM (Support Vector Machine). However, owing to various circumstances, such as changes in weather and lighting, it is difficult to recognize the traffic signs robustly using only SVM. In order to solve this problem, we propose a tracking algorithm with RANSAC-based motion estimation. Using two-point motion estimation, inlier feature points within the traffic sign are selected and then the optimal motion is calculated with the inliers through a bundle adjustment. This approach greatly enhances the traffic sign recognition performance.

• 한국항해학회지
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• 제20권3호
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• pp.43-63
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• 1996

The purpose of this study is to find out what is the functional role of VTS in order to get the people concerned with marine traffic/transportation understand about VTS. VTS could be described as the essential risk management system in both cost effective on cost-benefit analysis and the sea space or time management at port, coastal environment. The important role of the VTS are those functions such as the decision making infrastructure, the passive/active safety measures at sea. VTS could not control/regulate marine traffic as strong as ATC(Air Traffic Control) owing to the marine traffic characters. However, the right and responsibility of VTS finally are belong to the master, pilot and mariners. For the benefit of the electronic technology development, VTS system also cloud be upgraded to communication system from information system. In connection with these system upgrading, the right and responsibility of VTS/staff should be supported by domestic legal system. The followings are presented for VTS to be effective. First, the cooperation and understanding of VTS between the peoples concerned with marine traffic/transportation are essential. Because they are all data supplier and also information consumers. Second, VTS staff/regulator should be selected, educated, trained accordingly as per their career, ability, quality, qualification, certification and etc. Third, the port reliability from VTS users depends on the factors such as economic interests, safety and effectiveness/efficiency of VTS.

• 한국컴퓨터정보학회논문지
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• 제20권7호
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• pp.33-40
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• 2015

The time slot assignment problem (TSAP) or Satellite Communications scheduling problem (SCSP) for a satellite performs $n{\times}n$ ground station data traffic switching has been known NP-hard problem. This paper suggests $O(n^2)$ time complexity algorithm for TSAP of a satellite that performs $n^2{\times}n^2$ ground station data traffic switching. This problem is more difficult than $n{\times}n$ TSAP as NP-hard problem. Firstly, we compute the average traffic for n-transponder's basic coverage zone and applies ground station exchange method that swap the ground stations until all of the transponders have a average value as possible. Nextly, we transform the D matrix to $D_{LB}$ traffic matrix that sum of rows and columns all of transponders have LB. Finally, we select the maximum traffic of row and column in $D_{LB}$, then decide the duration of kth switch mode to minimum traffic from selected values. The proposed algorithm can be get the optimal solution for experimental data.

• 한국ITS학회 논문지
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• 제2권1호
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• pp.85-92
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• 2003

고속도로 신설 노선의 지속적인 개통은 목적지까지의 다양한 주행 경로를 선택 가능하게 하였고 교통정보의 적절한 활용은 상당한 편익을 가져오게 되었다. 그러나, 현재의 교통정보제공 시장은 진입 초기단계에 있어 교통정보의 가치가 적정하게 평가받지 못하고 기 제공중인 유사 정보를 기준으로 하여 정해지고 있는 실정이다. 따라서, 본 연구에서는 고속도로 교통정보의 적정한 가치를 산정하고자 최근 1년 이내 고속도로 운전 경험자 800명을 대상으로 서울과 수도권 지역, 고속도로 휴게소에서 설문을 실시하였고 표본추출 방법은 임의할당 추출법을 사용하였다. 그리고, 이 설문자료를 바탕으로 가격과 판매량의 관계인 가격반응함수를 구하여 최적 가격을 산정하는 가격민감도 분석 기법을 사용, 적정 가치를 산정하였다.

• 한국IT서비스학회지
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• 제14권4호
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• pp.257-267
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• 2015

We propose a vehicle-mounted, location-aware mobile digital signage system that can be used for public transportation through mobile communication. This paper proposes the installations of the LED display panels at the backside of the bus., which display traffic information to cars behind the bus. Information to be displayed would include, but is not limited to, road information, public commercials and private commercials. We propose the system architecture and further implement the prototype of mobile digital signage system for demonstration. The system is based on the Client-Server system. Each bus has a client terminal which detects the current location by a GPS receiver and sends its location information to the server using mobile communication function. The terminal device receives advertisements and traffic information from the server and displays it to the large LCD or LED panel installed at the inside and outside of the bus. We use the Android smartphone as a client system, which inherently equipped with GPS and mobile communication function. GPS detects the location of bus and reports its geo-location data to the traffic information center server via a wireless communication network. On the server side, we developed a specially designed control server, where it communicates with the other traffic information center and updates and manages the databases contents being displayed by each position. The server contains location dependent variable information and returns selected information back to the vehicle in real time. Spatial database is used to process location based data. Server system periodically receives the real time traffic information from the road information center database. And it process the information by bus location and bus line number. In this paper, we propose a mobile digital signage service and explain the system implementation of this service.