• International Journal of Naval Architecture and Ocean Engineering
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• 제11권1호
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• pp.202-210
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• 2019

The obstacles modeling is a fundamental and significant issue for path planning and automatic navigation of Unmanned Surface Vehicle (USV). In this study, we propose a novel obstacles modeling method based on high resolution satellite images. It involves two main steps: extraction of obstacle features and construction of convex hulls. To extract the obstacle features, a series of operations such as sea-land segmentation, obstacles details enhancement, and morphological transformations are applied. Furthermore, an efficient algorithm is proposed to mask the obstacles into convex hulls, which mainly includes the cluster analysis of obstacles area and the determination rules of edge points. Experimental results demonstrate that the models achieved by the proposed method and the manual have high similarity. As an application, the model is used to find the optimal path for USV. The study shows that the obstacles modeling method is feasible, and it can be applied to USV path planning.

• Journal of the Korean Institute of Landscape Architecture International Edition
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• 제2호
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• pp.114-119
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• 2004

By Article two of a Japanese urban park low, it prescribes park facilities strictly, and one of the classifications includes 'path and plaza'. In addition, it is assumed that we divide several kinds different paths of width by size of the park in a path design of a park with a textbook of park design in a trunk line path, the main path, a vice-path or a branch path and design it. From such a thing, in the path of an urban park, a line consists straight of fixed width, and it is most that one pattern is considered to be. Therefore, in modem urban park, a path and division of a plaza are lucid explanation. It is rare that the historical parks which generally former daimyo gardens are shown later, and is used as a kind of an urban park width of the path where was particularly posted in a strolling garden in that is fixed, and width waits straight for even a line and waits, and, for this, there is. As a result, it is a path and the situation that are hard to be distinguished of a plaza. Although there are a difference of design and a difference of pavement materials in modem landscape space when We watch road surface constitution of the path that We did that will let you wait, in gross We are uniform, and it is it with a result to be poor in change nature. From such an observation, this consideration compared traditional landscape space and modem landscape space with path width about two points of road surface constitution through the trial that a graph analyzed the actual place data which measured into and lectured on an ideal method of a park path from this.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권9호
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• pp.3194-3210
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• 2022

Wall obstruction is the main factor leading to the non-line of sight (NLoS) error of indoor localization based on received signal strength indicator (RSSI). Modeling and correcting the path loss of the signals through the wall will improve the accuracy of RSSI localization. Based on electromagnetic wave propagation theory, the reflection and transmission process of wireless signals propagation through the wall is analyzed. The path loss of signals through wall is deduced based on power loss and RSSI definition, and the theoretical model of path loss of signals through wall is proposed. In view of electromagnetic characteristic parameters of the theoretical model usually cannot be accurately obtained, the statistical model of NLoS error caused by the signals through the wall is presented based on the log-distance path loss model to solve the parameters. Combining the statistical model and theoretical model, a hybrid model of path loss of signals through wall is proposed. Based on the empirical values of electromagnetic characteristic parameters of the concrete wall, the effect of each electromagnetic characteristic parameters on path loss is analyzed, and the theoretical model of regional path loss of signals through the wall is established. The statistical model and hybrid model of regional path loss of signals through wall are established by RSSI observation experiments, respectively. The hybrid model can solve the problem of path loss when the material of wall is unknown. The results show that the hybrid model can better express the actual trend of the regional path loss and maintain the pass loss continuity of adjacent areas. The validity of the hybrid model is verified by inverse computation of the RSSI of the extended region, and the calculated RSSI is basically consistent with the measured RSSI. The hybrid model can be used to forecast regional path loss of signals through the wall.

• 한국통신학회논문지
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• 제34권12B호
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• pp.1371-1379
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• 2009

본 논문에서는 모바일 노드들의 움직임이 심한 MANET 환경에서 데이터의 전송을 보다 안정적이고 신뢰성 있게 하기 위해 소스 목적지 간의 다중 경로를 찾는 새로운 방법을 제시하고자 한다. 새로운 다중경로 라우팅은 먼저 AODV에 기반을 두어 주경로를 설정하고 주경로로 설정된 노드는 보조경로 탐색에 참여하지 못하도록 하여 주경로와 보조경로를 노드 비 겹침(disjoint)하게 형성한다. 또한 주경로가 설정된 후 바로 데이터 전송을 시작하고 데이터 전송이 되고 있는 중에 백그라운드로 보조경로 탐색을 실행하여 경로 탐색 시에 발생하는 데이터 전송의 지연을 주경로 탐색 시에만 발생하도록 한다. 주경로와 보조경로 중 하나의 경로가 단절되면 즉시 다른 경로로 데이터 전송을 하게 되고 단절된 경로는 경로유지를 통해 다시 노드 비 겹침 경로를 찾는다. Qualnet 기반 시뮬레이션을 수행한 결과, 제안한 라우팅 프로토콜을 사용한 경우 주경로가 단절되었을 때 62.5%정도 보조경로가 존재하여 보조경로를 통한 지연 없는 데이터 전송을 하며, AODV, AODV-Local Repair에 비해 패킷 전송률이 2~3%향상되고, 종단 간 지연시간이 10%정도 줄어든다.

• 산업경영시스템학회지
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• 제35권1호
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• pp.39-46
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• 2012

An unmanned aerial vehicle (UAV) is a powered aerial vehicle that does not carry a human operator, uses aerodynamic forces to provide vehicle lift, can fly autonomously or be piloted remotely, can be expendable or recoverable, and can carry a lethal or non-lethal payload. An UAV is very important weapon system and is currently being employed in many military missions (surveillance, reconnaissance, communication relay, targeting, strike, etc.) in the war. To accomplish UAV's missions, guarantee of survivability should be preceded. The main objective of this study is a local path planning to maximize survivability for UAV on the battlefield of dynamic threats (obstacles, surface-to-air missiles, radar etc.). A local path planning is capable of producing a new path in response to environmental changes. This study suggests a $Smart$ $A^*$ (Smart A-star) algorithm for local path planning. The local path planned by $Smart$ $A^*$ algorithm is compared with the results of existing algorithms ($A^*$ $Replanner$, $D^*$) and evaluated performance of $Smart$ $A^*$ algorithm. The result of suggested algorithm gives the better solutions when compared with existing algorithms.

• 지식경영연구
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• 제24권1호
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• pp.127-145
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• 2023

본 논문은 친환경 연료 중 하나인 수소 원료를 바탕으로 미래의 에너지 문제와 공해 문제를 해결할 수 있는 수소연료전지 기술 도메인에 대해 특허 분석을 실시했다. 특허분석은 현재 기술 수준과 미래 발전 방향을 발견할 수 있어 기술로드맵 수립에 많이 활용된다. 그러나 기존의 특허분석은 정성적인 분석 및 간단한 통계분석으로 현재의 기술 환경을 반영하지 않은 분석 결과를 제안할 수 없다. 현재의 기술 환경은 기술의 융복합으로 발전을 나타내고 있고, 발전 속도는 매우 가파르게 성장하여 정성적인 분석은 시대적 분석 요건에 옳지 않다. 그래서 본 논문은 현재의 기술환경을 반영한 지식상속성(Knowledge Persistence, KP) 기반의 주경로 분석과 텍스트마이닝 방법을 활용하여, 수소연로전지 기술도메인에서 핵심특허 발견, 중요 기술 발전, 유망기술을 조망한다.

• 한국정보통신학회논문지
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• 제14권10호
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• pp.2358-2364
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• 2010

최근 무선 센서 네트워크에서는 센서 노드의 에너지 소모뿐만 아니라 센서 노드에서 수집된 데이터의 무결성을 보장하기 위한 연구가 진행되고 있다. 그러나 기존 연구에서는 센서 노드로부터 데이터를 병합하는 클러스터 헤드의 오버헤드 및 데이터의 무결성을 보장하지 못하고 있다. 이 논문에서는 센서 노드로부터 전달된 데이터를 클러스터 헤드가 병합할 때 클러스터 헤드의 오버헤드를 줄이고 병합된 데이터의 무결성을 보장하기 위한 다중 경로 해쉬체인 기법을 제안한다. 제안된 기법은 데이터 병합시 클러스터 헤드의 데이터 무결성을 보장하기 위해서 주경로와 보조경로로 나누어 다중 해쉬 체인을 형성한다. 주경로 이외에 사용되는 보조 경로는 센서 노드의 인증 시 클러스터 헤드의 오버헤드를 최소화하면서 센서 노드의 무결성을 지원한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 추계학술대회 논문집
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• pp.687-692
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• 1993

This paper deals with the generation of laser scan path for manufacturing 3-dimensional body using StereoLithography. The purpose of this study is to develop one module of the StersoLithography system(SLA) for Rapid Protyping and Manufacturing. AutoCAD system is used to supply CAD information from model. The X-Y controller which was made for a special purpose is used to test this system. The system software developed is composed of 3 main modules, the first module is calculating the boundary point os laser scan path. The scound module is generating final output file which is used to down load on the controller. The result of this study shows a good algorithm to generate laser scan path on the basis of simple mathematical background.

• 제어로봇시스템학회논문지
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• 제5권5호
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• pp.593-599
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• 1999

A mobile robot in FMS environment should be able to nevigate itself. Therefore, path planning is necessary for the mobile robot to perform its tasks without being lost. Path planning using a network model gives oprimal paths to every pair of nodes but building this model demands accurate information of environments. In this paper, a method to build a network model using sonar sensors is presented. The main idea is to build a quad tree model by using sonar sensors and convert the model to a network model for path planning. The new method has been implemented on a mobile robot. Experimental results show that the mobile robot constructs an accurate network model using inaccurate sonar data.

• 한국소음진동공학회논문집
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• 제26권7호
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• pp.774-780
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• 2016

In this paper noise source and transfer path of tactical vehicle are analyzed with partial coherence function and spectrum analysis. Engine, transmission, structure panel and aerodynamic are main source of cabin noise. To reduce cabin noise, identifying transfer path of sources and analyzing their contribution is important. With modeling of transfer path and partial coherence function, transfer path and principal noise source can be identified. Engine/transmission and structural resonance are principal source of low frequency noise and by adding stiffener and sound absorbing material, resonance of vibration and inflow air problem can be solved.