• 대한전기학회논문지:시스템및제어부문D
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• 제54권5호
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• pp.291-299
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• 2005

An obstacle avoidance algorithm for a network-based autonomous mobile robot is proposed in this paper. The obstacle avoidance algorithm is based on the VFH(Vector Field Histogram) algorithm and two delay compensation methods with the VFH algorithm are proposed for a network-based robot with distributed environmental sensors, mobile actuators, and the VFH controller. Firstly, the environmental sensor information is compensated by prospection with acquired environmental sensor information, measured network delays, and the kinematic model of the robot. The compensated environmental sensor information is used for building polar histogram with the VFH algorithm. Secondly, a sensor fusion algorithm for localization of the robot is proposed to compensate the delay of odometry sensor information and the delay of environmental sensor information. Through some simulation tests, the performance enhancement of the proposed algorithm in the viewpoint of efficient path generation and accurate goal positioning is shown here.

• Journal of information and communication convergence engineering
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• 제8권6호
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• pp.709-715
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• 2010

This paper represents a map building and localization system for mobile robot. Map building and navigation is a complex problem because map integrity cannot be sustained by odometry alone due to errors introduced by wheel slippage, distortion and simple linealized odometry equation. For accurate localization, we propose sensor fusion system using encoder sensor and indoor GPS module as relative sensor and absolute sensor, respectively. To build a map, we developed a sensor based navigation algorithm and grid based map building algorithm based on Embedded Linux O.S. A wall following decision engine like an expert system was proposed for map building navigation. We proved this system's validity through field test.

• Smart Structures and Systems
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• 제7권5호
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• pp.393-416
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• 2011

Hybrid acceleration-impedance sensor nodes on Imote2-platform are designed for damage monitoring in steel girder connections. Thus, the feasibility of the sensor nodes is examined about its performance for vibration-based global monitoring and impedance-based local monitoring in the structural systems. To achieve the objective, the following approaches are implemented. First, a damage monitoring scheme is described in parallel with global vibration-based methods and local impedance-based methods. Second, multi-scale sensor nodes that enable combined acceleration-impedance monitoring are described on the design of hardware components and embedded software to operate. Third, the performances of the multi-scale sensor nodes are experimentally evaluated from damage monitoring in a lab-scaled steel girder with bolted connection joints.

• 센서학회지
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• 제28권3호
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• pp.152-156
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• 2019

An ultraviolet (UV) image sensor is an extremely important optoelectronic device used in scientific and medical applications because it can detect images that cannot be obtained using visible or infrared image sensors. Because photodetectors and transistors are based on different materials, conventional UV imaging devices, which have a hybrid-type structure, require additional complex processes such as a backside etching of a GaN epi-wafer and a wafer-to-wafer bonding for the fabrication of the image sensors. In this study, we developed a monolithic GaN UV passive pixel sensor (PPS) by integrating a GaN-based Schottky-barrier type transistor and a GaN UV photodetector on a wafer. Both individual devices show good electrical and photoresponse characteristics, and the fabricated UV PPS was successfully operated under UV irradiation conditions with a high on/off extinction ratio of as high as $10^3$. This integration technique of a single pixel sensor will be a breakthrough for the development of GaN-based optoelectronic integrated circuits.

• 한국의류산업학회지
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• 제10권4호
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• pp.473-478
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• 2008

Since the late 1990, "Smart clothing" has been developed in a various way to meet user centered design and human engineering that considered usability, wearability with clothing. Under this circumstance, research and development of smart clothing has been demanded usability and wearability test. But, Study of the usability evaluation for sensor based smart clothing is insufficient. In this study, we suggest criterion of usability evaluation for sensor based smart clothing that evaluate on the point of view such as wearability of clothing, interaction of clothing and devices, interaction of body and devices. we performed qualitative and quantitative test with developed smart clothing to present usability evaluation criterion for sensor based smart clothing. As a result, total 7 categories such as 'usefulness', 'wearability', 'appearance', 'riskness', 'facility of management', 'perceived change', were extracted as the usability and wearability criterion. Additionally, 28 factors of evaluation criterion for sensor based smart clothing were indicated on the result of this research. This study have meaning to indicate usability evaluation criterion for sensor based smart clothing.

• 한국정밀공학회지
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• 제28권4호
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• pp.436-445
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• 2011

As automation systems become intelligent and autonomous for productibility, industrial networks (fieldbuses) and network-based devices are essential components of intelligent manufacturing systems. However, there are obstacles for the wide acceptance of the network-based devices such as smart sensor and network-based actuator. First, there exist numerous fieldbus protocols that a network-based device should be able to support. Second, the whole network-based device has to be replaced when only the sensor of the module fails. In order to overcome these obstacles, a smart sensor/actuator is implemented as two units; one responsible for network communication and the other for sensor/actuator operations using IEEE 1451.0 standard. This paper presents a structure of the 1451.0-based smart sensor with multiple connectivity function designed by CANopen.

• 정보처리학회논문지C
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• 제15C권1호
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• pp.9-18
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• 2008

센서 노드의 프로그램 변경을 통한 센서 네트워크 공격을 방지하는 것은 중요한 센서 네트워크 관련 보안요소들 중 하나이다. 이를 해결하기 위해 각 센서 노드 내에서 실행 중인 코드가 변경되지 않았음을 검증하는 소프트웨어 기반 검증(attestation) 기술이 사용되고 있다. 그러나 현재 제안되고 있는 소프트웨어 기반 검증 기법은 신뢰할 수 있는 검증자가 존재하지 않는 센서 네트워크 환경에 대한 고려가 부족할 뿐만 아니라, 망의 변화가 없는 정적인 환경에 중점을 두어 설계되었기 때문에 센서 네트워크 환경에 적합하지 않다. 본 논문에서는 SWATT(Software-based ATTestation) 기법을 이용하여 센서 네트워크 환경에 적합한 상호 검증 프로토콜을 제안한다. 제안 기법은 신뢰 노드가 존재하지 않는 센서 네트워크 환경에서 이웃한 센서 노드에게 자신의 존재를 주기적으로 알리되, SWATT 기법을 이용하여 이를 인지한 이웃 센서 노드와 상호 검증을 수행하도록 한다. 이를 통해 신뢰할 수 있는 검증자가 없는 센서 네트워크 환경에서 악의적인 공격으로 인해 변경된 프로그램을 실행하는 센서 노드를 식별할 수 있으며, 결과적으로 검증된 센서 노드들만으로 이루어지는 네트워크 구성이 가능하도록 한다.

• Journal of Electrical Engineering and Technology
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• 제7권6호
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• pp.1009-1013
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• 2012

A relationship between the sensor placement and the PDOP (Position Dilution of Precision) is derived in the TDOA-based localization system. And the geometric condition of the sensor placement is analyzed in order to get a minimum PDOP based on the derived relationship. Through computer simulations, effect of the sensor placement on the PDOP is observed.

• 한국컴퓨터정보학회논문지
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• 제21권10호
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• pp.99-105
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• 2016

The active rule system is a key element of the rule-based mobile agent middleware system for activeness and autonomy of the sensor network. The rule manager, which is the main components of active rule based mobile agent framework and active rule system, performs the control and management of the rule-related processes. In this paper, we design and implement the roles and functions of the rule manager in detail. The proposed rule manager plays an important role in the sensor network environment. The sensor data server loads the active rule on the mobile agent by the rule manager according to the situations, and the mobile agent migrates to the destination node and performs the designated action. This active rule-based mobile agent middleware system presents the usefulness for the various sensor network applications. Through the rule execution experiment using the rule-based mobile agent, we show the adaptability and applicability of rule-based mobile agent middleware system to the dynamic environmental changes in sensor networks.

• 인터넷정보학회논문지
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• 제11권1호
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• pp.129-141
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• 2010

본 논문에서는 사람의 행동 모니터링을 위한 멀티 센서 기반의 웨어러블 지능형 디바이스를 제안한다. 다중 행동을 인식하기 위해, 이미지 센서와 가속도 센서를 이용하여 행동 인식 알고리즘을 개발하였다. 멀티 센서로부터 얻은 데이터를 분석하기 위해 그리드 기반 옵티컬 플로우 방법을 제안하고 SVM 분류기법을 이용하였다. 이미지 센서로부터 얻은 모션 벡터의 방향과 크기를 이용하였고, 3축 가속도 센서로부터 얻은 데이터에서 FFT의 축과 크기와의 상관관계를 계산하였다. 실험 결과에서 이미지 센서 기반과 3축 가속도 센서기반의 행동 인식률은 각각 55.57 %, 89.97%를 보였으나 제안한 멀티센서기반의 행동인식률은 92.78% 를 보였다.