• 대한원격탐사학회지
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• 제19권1호
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• pp.81-89
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• 2003

A provision of spatial information is expected to make a market explosion in various fields. A distribution of spatial data on wireless mobile environments indicates a huge expansion of mobile technology as well as a spread of geospatial applications. For high-qualified spatial information, the 4S technology Project that is integrating four kinds of spatial systems is currently being executed with the goal of nationwide integration of spatial data and spatial information systems. In terms of network environments, a mobile ad hoc network where mobile terminals communicate with each other without any infrastructures has been standardized for the next generation mobile wireless network. With respect to the future technologies for spatial information, it is necessary to design 4S applications on mobile ad hoc networks. This paper addresses the issue, which is proposing design concepts for distributing 4S spatial data on mobile ad hoc networks and for ad hoc styled 4S applications.

• 융합신호처리학회논문지
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• 제8권4호
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• pp.266-271
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• 2007

이동 채널 환경에서 신호는 다중경로 페이딩의 영향으로 통신품질이 크게 저하된다. 지금까지 이러한 페이딩의 영향은 기지국과 이를 중심으로 움직이는 이동 단말간의 이동 채널환경에서 고려되어왔다. 그러나 텔레매틱스 등과 같은 향후의 이동통신 서비스는 기지국과 같은 인프라를 통한 통신뿐만 아니라 단말기간 이동 ad-hoc통신도 활용될 것이므로 이런 통신환경에서의 페이딩 영향을 분석하고 다이버시티 기법에 대해 연구할 필요가 있다. 본 논문에서는 두 대의 차량을 이용하여 이동 통신 채널을 측정하고, 이 데이터를 활용하여 선형 빔형성 안테나의 페이딩 성능을 분석하였다. 채널 측정은 전 방향 안테나가 장착된 이동 차량에서 2GHz 대역의 QPSK 신호를 전송하고, 선형배열 안테나가 장착된 차량을 일정 지역을 이동하면서 수신 신호를 저장하였다. 빔 형성 안테나 기법의 페이딩 성능은 전방향 안테나에 대한 페이딩 마진의 향상 정도를 분석하였으며 선택 다이버서티를 사용한 경우와 비교하였다. 측정 데이터로부터 페이딩 깊이에 따른 CDF를 분석한 결과, 빔 형성 기술을 적용하면 선택 다이버서티를 적용한 경우에 비해 페이딩 마진이 페이딩 환경에 따라 6-7dB 향상됨을 알 수 있었다.

• 한국통신학회논문지
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• 제31권11A호
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• pp.1120-1129
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• 2006

무선 ad-hoc 네트워크 환경에서 이동 호스트의 배터리 수명을 최대화하는 것은 시스템의 수명과 성능을 향상시키므로 매우 중요하다. 이동 호스트들은 라우팅 역할을 수행하므로 네트워크의 구조와 이동 호스트들의 위치에 따라 이동 호스트들의 에너지 소비의 차이가 발생된다. 본 논문에서 각 이동 호스트는 에너지 트리를 유지하며, 메시지 트리 패킷을 이용하여 이웃 이동 호스트들의 에너지의 양을 주기적으로 파악한다. 이동 호스트는 패킷을 전송하기 위한 라우팅 경로를 설정할 때 에너지 트리와 너비우선 탐색을 이용하여 에너지 소비가 가장 적절한 경로를 선택한다. 제안기법은 무선 ad-hoc 네트워크 환경에서 각 이동 호스트의 에너지의 양이 균등하게 사용됨으로써 제한된 배터리 용량을 가진 이동 호스트들이 최대한 오랫동안 동작하므로 시스템의 수명과 성능을 향상시킨다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1184-1189
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• 2003

Map building and position estimation capabilities are practically indispensable for a mobile robot to execute its given tasks in its working environments. An autonomous map building method and a smart localization method is proposed in our previous works. The experimental verifications are carried out in this paper. We applied the proposed algorithms to mobile service robots in large-scale indoor buildings. Experimental results show that our strategy is reliable and feasible in tough conditions like non-polygonal and dynamic environments. The advantages of the algorithms are well-illustrated through real experiments.

• 한국산업융합학회 논문집
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• 제21권3호
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• pp.125-131
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• 2018

In this paper, we propose a homogeneous multisensor-based navigation algorithm for a mobile robot, which is intelligently searching the goal location in unknown dynamic environments with moving obstacles using multi-ultrasonic sensor. Instead of using "sensor fusion" method which generates the trajectory of a robot based upon the environment model and sensory data, "command fusion" method by fuzzy inference is used to govern the robot motions. The major factors for robot navigation are represented as a cost function. Using the data of the robot states and the environment, the weight value of each factor using fuzzy inference is determined for an optimal trajectory in dynamic environments. For the evaluation of the proposed algorithm, we performed simulations in PC as well as real experiments with mobile robot, AmigoBot. The results show that the proposed algorithm is apt to identify obstacles in unknown environments to guide the robot to the goal location safely.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.729-734
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• 2005

One of the important research issues in mobile robot is how to detect the 3D environment fast and accurately, and recognize it. Sensing methods of utilizing laser structured light and/or stereo vision are representatively used among a number of methodologies developed to date. However, the methods are still in need of achieving high accuracy and reliability to be used for real world environments. In this paper to implement a new robotic environmental sensing algorithm is presented by combining the information between intensity image and that of laser structured light image. To see how effectively the algorithm applied to real environments, we developed a sensor system that can be mounted on a mobile robot and tested performance for a series of environments.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.532-532
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• 2000

Conventional artificial intelligence systems are not properly responding under dynamically changing environments. To overcome this problem, reactive planning systems implementing new Al principles, called behavior-based Al or emergent computation, have been proposed and confirmed their usefulness. As another alternative, biological information processing systems may provide many feasible ideas to these problems. Immune system, among these systems, plays important roles to maintain its own system against dynamically changing environments. Therefore, immune system would provide a new paradigm suitable for dynamic problem dealing with unknown environments. In this paper, a new approach to behavior-based Al by paying attention to biological immune system is investigated. The feasibility of this method is confirmed by applying to behavior control of an autonomous mobile robot in cluttered environment.

• 한국통신학회논문지
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• 제29권5A호
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• pp.537-544
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• 2004

In this paper, we p개pose DS-CDM-SQAM(Superposed Quadrature Amplitude Modulation) which is characterized by its smooth phase transition and small envelope fluctuation, and improves the power efficiency as compared to DS-CDM-QPSK of satellited-based DMB system(ITR-R BO.1130-4 System E) in a nonlinearly amplified channel. Computer simulation results show that the proposed DS-CDM-SQAM improves Eb/No by 1.7㏈ to maintain BER=1${\times}$$10^{-3}$ in nonlinearly amplified multipath mobile radio environments. Therefore, the proposed DS-CDM-SQAM system significantly improves the power efficiency in nonlinear land mobile satellite DMB environments.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제6권4호
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• pp.314-320
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• 2006

Navigation in environments that are densely cluttered with obstacles is still a challenge for Autonomous Ground Vehicles (AGVs), especially when the configuration of obstacles is not known a priori. Reactive local navigation schemes that tightly couple the robot actions to the sensor information have proved to be effective in these environments, and because of the environmental uncertainties, STSF(Space and Time Sensor Fusion)-based fuzzy behavior systems have been proposed. Realization of autonomous behavior in mobile robots, using STSF control based on spatial data fusion, requires formulation of rules which are collectively responsible for necessary levels of intelligence. This collection of rules can be conveniently decomposed and efficiently implemented as a hierarchy of fuzzy-behaviors. This paper describes how this can be done using a behavior-based architecture. The approach is motivated by ethological models which suggest hierarchical organizations of behavior. Experimental results show that the proposed method can smoothly and effectively guide a robot through cluttered environments such as dense forests.

• Journal of information and communication convergence engineering
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• 제11권1호
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• pp.24-29
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• 2013

In this paper, we propose a fuzzy inference model for a navigation algorithm for a mobile robot that intelligently searches goal location in unknown dynamic environments. Our model uses sensor fusion based on situational commands using an ultrasonic sensor. Instead of using the "physical sensor fusion" method, which generates the trajectory of a robot based upon the environment model and sensory data, a "command fusion" method is used to govern the robot motions. The navigation strategy is based on a combination of fuzzy rules tuned for both goal-approach and obstacle-avoidance based on a hierarchical behavior-based control architecture. To identify the environments, a command fusion technique is introduced where the sensory data of the ultrasonic sensors and a vision sensor are fused into the identification process. The result of experiment has shown that highlights interesting aspects of the goal seeking, obstacle avoiding, decision making process that arise from navigation interaction.