• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.4
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• pp.131-140
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• 2012

The shortest path search algorithm of navigation is generally based on Dijkstra algorithm and considers only the distance using the weight. Dijkstra algorithm based on the distance mainly ought to perform the 'number of nodes 1' and requires a lot of memory, for it is to start from the starting node and to decide the shortest path for all the nodes. Also, it searches only the same identical path in case of any bottleneck due to an accident nearby, since it is based only on the distance, and hence does not have a system that searches the detour road. In order to solve this problem, this paper considers only the travelling time per road (travelling speed * distance), without applying speed criteria (smoothness, slow speed, stagnation and accident control) or road class (express road, national road and provincial road). This provides an advantage of searching the detour, considering the reality that there are differences in time take for the car to travel on different roads with same distance, due to any accident, stagnation, or repair construction. The suggested algorithm proves that it can help us to reach the destination within the shortest time, making a detour from any congested road (outbreak) on providing an information on traveling time continuously(real-time) even though there is an accident in a particular road.

• Journal of the Korea Society of Computer and Information
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• v.20 no.1
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• pp.85-92
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• 2015

As computer game maps get more elaborate, path-finding by using $A^*$ algorithm in grid-based game maps becomes bottlenecks of the overall game performance. It is because the search space becomes large as the number of nodes increases with detailed representation in cells. In this paper we propose an efficient pathfinding method in which the computer game maps in a regular grid is converted into the polygon-based representation of the list of vertices and then the visibility information about vertices of polygons can be utilized. The conversion to the polygon-based map does not give any effect to the real-time query process because it is preprocessed offline. The number of visited nodes during search can be reduced dramatically by designing heuristics using visibility information of vertices that make the accuracy of the estimation enhanced. Through simulations, we show that the proposed methods reduce the search space and the search time effectively while maintaining the advantages of the grid-based method.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.15-18
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• 2003

ATSC 방식을 사용하는 DTV 수신기는 심볼 타이밍 동기를 맞추기 위해 77.3㎲마다 존재하는 세그먼트 싱크를 이용한 방법 또는 가드너 알고리즘을 사용한다. 이 중 가드너 알고리즘을 사용하는 방법은 다중 경로 채널 환경으로 인해 타이밍 옵셋이 발생한다. DTV 수신 채널 환경이 많은 수의 다중 경로 신호를 포함하고 있기 때문에 가드너 알고리즘을 사용한 DTV 수신기는 타이밍 옵셋이 발생한다. 이 타이밍 옵셋은 샘플링 순간을 잘못된 시점으로 옮기기 때문에 등화기의 성능이 열화된다. 다중 경로 채널 환경에서 등화기의 성능을 최적화하는 샘플링 순간은 주 경로 신호의 크기가 최대가 되는 점이다. 본 논문에서는 타이밍 옵셋 보상기를 사용하여 샘플링 순간을 주 경로 신호의 최대점으로 옮겨 타이밍 옵셋을 보상하고 등화기로 입력되도록 하여 DTV 수신 성능을 개선하였다. 타이밍 옵셋 보상기는 채널 상관기, 최대점 탐색기, 타이밍 보상용 보간 필터로 구성되어 있다. 타이밍 옵셋 보상기와 등화기를 연계 실험하여 성능 향상을 분석하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3B
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• pp.175-182
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• 2006

In this paper, we propose a Localized Adaptive QoS Routing Scheme using POMDP and Exploration Bonus Techniques. Also, this paper shows that CEA technique using expectation values can be simply POMDP problem, because performing dynamic programming to solve a POMDP is highly computationally expensive. And we use Exploration Bonus to search detour path better than current path. For this, we proposed the algorithm(SEMA) to search multiple path. Expecially, we evaluate performances of service success rate and average hop count with $\phi$ and k performance parameters, which is defined as exploration count and intervals. As result, we knew that the larger $\phi$, the better detour path search. And increasing n increased the amount of exploration.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.529-532
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• 2003

본 논문은 UWB(Ultra Wide-band) 통신 시스템에서 효과적인 신호 검출 알고리즘을 제안한다. UWB 통신 시스템은 차세대 통신 시스템으로 각광 받고 있는 기술로써, 매우 낮은 파워의 송신 신호를 사용한다. 그로 인해 잡음 및 다중 경로 환경하에서 신호 검출 알고리즘이 시스템 성능에 매우 중요한 부분으로 작용한다. 제안된 알고리즘은 신호 검출 성능을 높이기 위해, 신호의 정확한 위치를 잡는 Tracking과정에서 사용되는 DLL 구조를 활용하여 보다 세밀한 신호 탐색이 가능하다. 실험 결과 신호 위치를 기준으로 신호길이의 1/3 내에서 신호를 검출할 확률이 AWGN 15dB 이하에서 30% 정도 높아짐을 확인하였다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.2
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• pp.370-376
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• 2022

Smart ships related studies are being conducted in various fields owing to the development of technology, and an engine room patrol robot that can patrol the unmanned engine room is one such study. A patrol robot moves around the engine room based on the information learned through artificial intelligence and checks the machine normality and occurrence of abnormalities such as water leakage, oil leakage, and fire. Study on engine room patrol robots is mainly conducted on machine detection using artificial intelligence, however study on movement and control is insufficient. This causes a problem in that even if a patrol robot detects an object, there is no way to move to the detected object. To secure maneuverability to quickly identify the presence of abnormality in the engine room, this study experimented with whether a patrol robot can determine the shortest path by applying the A* algorithm. Data were obtained by driving a small car equipped with LiDAR in the ship engine room and creating a map by mapping the obtained data with SLAM(Simultaneous Localization And Mapping). The starting point and arrival point of the patrol robot were set on the map, and the A* algorithm was applied to determine whether the shortest path from the starting point to the arrival point was found. Simulation confirmed that the shortest route was well searched while avoiding obstacles from the starting point to the arrival point on the map. Applying this to the engine room patrol robot is believed to help improve ship safety.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.4
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• pp.624-632
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• 2022

Relationship networks such as an interpersonal relationship network or navigation route search can be expressed in graph form. However, as the amount of data increase, there is a problem that it is difficult to search for the desired data when it is displayed on one screen. In this paper, we propose a visualization method for searching for people, searching for the shortest path between people, and using graphs to express an interpersonal relationship network with many nodes. Unlike the search for the shortest path in the routing table, the shortest path in the interpersonal relationship network should be changeable according to the intension or importance of the researcher or user who is analyzing it. To this end, the BFS algorithm was modified to apply the characteristics of the interpersonal relationship network. For the verification of the results, the data in the character relationship information of the Korean Classics DB in the Korean Classics Translation Institute was used.

• Journal of Korea Society of Industrial Information Systems
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• v.8 no.3
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• pp.91-98
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• 2003

Visitors who browse the web from wireless PDAs, cell phones are frequently frustrated by interfaces. Simply replacing graphics with text and reformatting tables does not solve this problem, because deep link structures can still require more time. To solve this problem, in the paper we propose an algorithm, Minimal Path Algorithm that automatically improves wireless web navigation by suggesting useful shortcut links in real time. In the result of this paper, Minimal Path algorithm offer the shortcut and the number of shortest links to web users.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.113-116
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• 2007

This paper describes the development of an optimal 3D maze path game as web-based game contents. Client user using web can access and run java applet program with download of java byte code with the independence of hardware system. The optimal 3D maze path game developed in this paper consists of random maze path generation module, selected path input module, weighted optimal path search module, and path comparison module. It enhances the cognition faculty of game users with the comparison of the maze path searched by optimal path search algorithm and the selected maze path by game users.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.671-674
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• 2005

This paper describes the development of an optimal maze path game as web-based game contents. Client suer using web can access and run java applet program with download of java byte code with the independence of hardware system. The optimal maze path game developed in this paper consists of random maze path generation module, selected path input module, weighted optimal path search module, and path comparison module, selected path input module, weighted optimal path search module, and path comparison module. It enhances the cognition faculty of game users with the comparison of the maze path searched by optimal path search algorithm and the selected maze path by game users.