• 대한기계학회논문집
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• 제18권11호
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• pp.2902-2912
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• 1994

The ultrasonic array sensor system, consisting of one transmitter and fourreceivers instead of the traditional combination of a transmitter and a receiver is proposed in order to identify the location of objects. From the theoretical analysis and the experimental results, it is found that this new array sensor system could derive the information on the position of objects accurately, while the traditional sensor system could provide only the informatioin on the distance to objects. This sensor system is used to develop a sonar-based local mapping algorithm. The local map is used to find the existence of possible gates, through which the mobile robots can pass, and to select the suitable one in order for the robots to reach the goal safely in the presence of obstacles. The performance of the proposed local map algorithm is demonstrated experimentally in a small working area with several obstacles. It is found that the quality of the resulting local map is sufficient for the avoidance of collisions between the robots and obstacles and for the selection of the suitable gate leading to the goal. It is also shown that the global map of the working area could be obtained by integrating several local maps constructed from different locations and that it matches the actual layout of the working area well.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2004년도 춘계 종합학술대회 논문집
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• pp.522-528
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• 2004

이동통신망 진화와 함께 다기능 단말기를 기반으로 한 무선인터넷 서비스가 활성화되고 있다. 무선인터넷 서비스는 브라우저 기반의 정보서비스와 다운로드 플랫폼을 사용하는 이동멀티미디어 서비스가 제공되고 있다. 다기능 단말기보급이 확산됨에 따라 이를 기반으로 한 신규서비스 개발이 활발하게 이루어지고 있다. 본 논문은 무선인터넷 서비스에서 핵심서비스로 발전할 위치기반 서비스를 위한 모발일 맵 브라우저로, 개발된 맵 브라우저는 국내 무선인터넷 플랫폼인 WIPI를 사용하여 GIS 서버와 연동하여 지도정보를 제공한다. 또한 개발된 시스템은 위치정보 서비스 이외에 텔레메틱스를 위한 GIS 플랫폼으로 사용되고, 향후 WIPI 플랫폼 확산과 더불어 PDA, 텔레메틱스 단말기 등에서도 서비스가 가능할 것이다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2001년도 추계종합학술대회
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• pp.89-92
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• 2001

Mobile IP 망에서 보다 좋은 품질의 서비스를 제공하기 위한 하나의 방법으로 RSVP 및 WFQ를 제안하였다. 성능평가를 위하여 Mobile IP와 VoIP 네트워크 Model를 구성하였고, 지연 및 QoS에 관한 성능평가를 실시하였다. 성능평가 결과 Mobile agent 가 이동전에는 2ms, 이동후에는 3ms, QoS를 적용하기 전에는 30ms, QoS를 적용한 후에는 10ms가 분석되었다. 본 논문에서는 QoS를 적용하여 Mobile IP 망에서 지연 문제를 개선시켰다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 심포지엄 논문집 정보 및 제어부문
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• pp.258-260
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• 2005

We describe a method for localizing a mobile robot in the working environment using a vision system and VRML. The robot identifies landmarks in the environment and carries out the self-positioning. The image-processing and neural network pattern matching technique are employed to recognize landmarks placed in a robot working environment. The robot self-positioning using vision system is based on the well-known localization algorithm. After self-positioning, 2D scene is overlaid with VRML scene. This paper describes how to realize the self-positioning and shows the result of overlaying between 2D scene and VRML scene. In addition we describe the advantage expected from overlapping both scenes.

• 인터넷정보학회논문지
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• 제9권4호
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• pp.29-41
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• 2008

현재 IETF MANEMO (Mobile Adhoc for NEMO) 워킹 그룹에서는 중첩 NEMO의 내부 라우팅 지원 방안에 관한 표준을 준비중이다. 그러나 중첩 NEMO에서는 MIPv6나 기본 NEMO 프로토콜에서 발생하지 않는 중첩 토폴로지 특성을 갖는다. 따라서 기존 이동성 지원 프로토콜에서는 발생하지 않는 예외적인 이동 특성이 발생한다. 이러한 이동 특성은 네트워크 재설정에 대한 각기 다른 타입을 유발한다. 본 논문은 중첩 NEMO에서 발생 가능한 새로운 이동 패턴을 분류하고 분석하였다. 결론적으로 본 논문에서는 토폴로지 특성과 주소 설정 방안에서 발생하는 새로운 이동 타입과 재설정 패턴을 정의하고 분석적인 접근을 통해서 문제점을 도출하고 요구사항을 제시하고 있다.

• 한국IT서비스학회지
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• 제12권4호
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• pp.435-447
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• 2013

If we use a smartphone to analyze and detect falling, it is a huge advantage that the person with a sensor attached to one's body is free from awareness of difference and limitation of space, unlike attaching sensors on certain fixed areas. In this paper, we suggested effective posture analysis of smartphone users, and fall detecting system. Suggested algorithm enables to detect falling accurately by using the fact that instantaneous change of acceleration sensor is different according to user's posture. Since mobile applications working on smart phones are low in compatibility according to mobile platforms, it is a constraint that new development is needed which is suitable for sensor equipment's characteristics. In this paper, we suggested posture analysis algorithm using smartphones to solve the problems related to user's inconvenience and limitation of development according to sensor equipment's characteristics. Also, we developed fall detection system with the suggested algorithm, using hybrid mobile application which is not limited to platform.

• 대한기계학회논문집
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• 제17권9호
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• pp.2191-2204
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• 1993

A sensor system has been developed to measure the posture(position and orientation) of mobile robots working in industrial environments. The proposed sensor system consists of a CCD camera, retro-reflective landmarks, a strobe unit and an image processing board. The proposed hardware system can be built in economic price compared to commercial vision systems. The system has the capability of measuring the posture of mobile robots within 60 msec when a 386 personal computer is used as the host computer. The experimental results demonstrated a remarkable performance of the proposed sensor system in the posture measurement of mobile robots - the average error in position is less than 3 mm and the average error in orientation is less than 1.5.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.509-512
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• 2002

We propose a control method for mobile robot system using the bluetooth. The control packet is defined and used for control of the mobile robot. The control packet is composed of behavior components and has reserved packets for future working. The control packet has to be simple and provide commands to the mobile robot, since the bluetooth has a limited bandwidth. The data transmission rate and the distance, which can control the mobile robot in various circumstances, for example, corridor, yard, and room are measured by some experiments.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권12호
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• pp.3135-3148
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• 2013

The popularization of streaming networks and mobile devices brings a new kind of network called mobile peer-assisted streaming network. In this network, service provider not only offers downloading services, but also pre-pushes resources to users for caching. Users can download their demanded resources while working as servers for uploading the cached data. Also the mobile characteristic makes high package losing probability in this network. So we study how the service provider pre-pushes or the user downloads resources efficiently and effectively while considering the package losing in this paper. We build utility models for service provider and user, and solve the models using Bellman's theory to achieve Nash Equilibrium which shows the service provider's optimal pre-pushing speed and user's optimal downloading speed. The numerical simulation demonstrates the efficiency and effectiveness of our proposed pre-pushing and downloading scheme by comparing to the traditional scheme.

• 동력기계공학회지
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• 제4권4호
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• pp.78-83
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• 2000

It is often necessary to observe the working environment of a robot to control it efficiently in the remote location. The remote sensing data and control commands are transmitted via various media such as radio, microwave, and computer network. The World Wide Web can be used as the infrastructure for teleoperation of mobile robots. In this paper we propose an advanced technique of the remote control of mobile robots on the web. For the real-time control, the image separation algorithm is proposed to transmit the current positions of mobile robots instead of transmitting the full frame image. It is shown by experiments that the proposed algorithm is effective.