• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.4_1
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• pp.363-371
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• 2014

Most space-borne optical scanning systems adopt linear arrayconfigurations. The well-knownthree different types of space-borne sensors arealong-track line scanner, across-track linescanner, and three line scanner. To acquire accurate location information of an object on the ground withthose sensors, the exterior and interior orientation parameters are critical factors for both of space-borne and airborne missions. Since the imaging geometry of sensors mightchange time to time due to thermal influence, vibration, and wind, it is very important to analyze the Interior Orientation Parameters (IOP) effects on the ground. The experiments based on synthetic datasets arecarried out while the focal length biases are changing. Also, both high and low altitudes of the imagingsensor were applied. In case with the along-track line scanner, the focal length bias caused errors along the scanline direction. In the other case with the across-track one, the focal length bias caused errors alongthe scan line and vertical directions. Lastly, vertical errors were observed in the case ofthree-line scanner. Those results from this study will be able to provide the guideline for developing new linearsensors, so as for improving the accuracy of laboratory or in-flight sensor calibrations.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.2
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• pp.36-43
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• 2004

In this paper, the frequency spectra from respective mechanical noise signals detected using ultrasonic wave and AE(Acoustic Emission) sensor were analysed to under spark generation between brush and commutator side with arbitrarily 15$^{\circ}$ rotation for brush from the DC motor in operation. Also, the frequency spectra from respective magnetizing noise signals detected using ultrasonic wave and AE sensor were analysed to under neutral point for brush from the DC motor in normal operation. And the analyses and comparison between the mechanical noise signal and magnetizing noise signal of ultrasonic wave with brush location change from the DC motor in operation. As the experimental results, tile mechanical noise signal of ultrasonic wave under spark generation between brush and commutator side with brush location change from the DC motor in operation were increased about 2.5∼3.0 times than magnetizing noise signal of ultrasonic wave form the DC motor in normal operation. Also, the main frequency band for mechanical noise signals of AE under spark generation between brush and commutator side with brush location change from the DC motor in operation, appeared about 1.3[MHz]∼l.5[MHz] by the fast fourier transform.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.6
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• pp.11-15
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• 2009

Recently, a new PSC (Prestressed Concrete) bridge system, which is supported by Concrete-filled fiber-reinforced polymer (CFFRP) strut, has been introduced. This bridge is able to reduce self-weight and increase the width of traditional PSC bridges. However, no relevant research has been reported on local behavior of CFFRP strut in the bridge system. The purpose of this study is to investigate local behavior of CFFRP struts using fiber Bragg grating (FBG) sensors. Field tests were performed to examine the hoop strains and longitudinal strains of the FRP strut under various lateral positions and velocities of a test truck. It has been observed that CFFRP strut is under compression regardless of vehicle speed and location. However, the CFFRP strut is sensitive to the lateral position of vehicles in terms of strain magnitude. Results also indicated that the FBG sensors can faithfully record the hoop and longitudinal strains of the FRP strut without electro-magnetic interference.

• Journal of the Korean GEO-environmental Society
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• v.14 no.4
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• pp.47-52
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• 2013

In Korea, the number of mining operations are getting smaller. But buried accidents are on the increase every year. For this reason, it is important to safety management in construction process, especially the worker's safety. In the field of construction needs utilization of integration system according to purpose of utilization, particularly in underground construction sites utilizing is emphasized even more. The current element technologies of location tracking, sensors and wireless communication possible to utilize but it is still difficult to utilization of integration system in construction field because a study is not complete on commercialization and availability. In this study, for real time 3-dimensional management of ubiquitous construction site in ground and underground, measure data using MEMS sensor, EDM and DGPS in 2 test site. Also results were analysed by MATLAB. As a result, error is verification less than 3 meter that possible to distinguish with the naked eye and construct direction of study based on result of former.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.3
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• pp.353-360
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• 2012

This paper describes a SLAM method which estimates landmark locations and robot pose simultaneously. The particle filter can deal with nonlinearity of robot motion as well as the non Gaussian property of robot motion uncertainty and sensor error. The state to be estimated includes the locations of landmarks in addition to the robot pose. In the experiment, four beacons which transmit ultrasonic signal are used as landmarks. The robot receives the ultrasonic signals from the beacons and detects the distance to them. The method uses rang scanning sensor to build geometric feature of the environment. Since robot location and heading are estimated by the particle filter, the scanned range data can be converted to the geometric map. The performance of the method is compared with that of the deadreckoning and trilateration.

• Journal of Navigation and Port Research
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• v.37 no.3
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• pp.309-313
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• 2013

This paper is about a complex sensor system of an automatic guided vehicle(AGV) for loading and unloading payloads. For the AGV to approach to the target rack for loading and unloading the payload, a way to identify the position and orientation was studied. To identify the position and orientation of the AGV accurately, a complex sensor system composed of RFID, IMU, and limit sensors was developed, and the performance of each sensor was undertaken. A model AGV was constructed, and the good performance of the developed complex sensor system was verified through performance experiments.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.209-212
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• 2009

최근 국내에서 적용되고 있는 콘크리트 충진 FRP 스트럿은 시공성 및 경제성 면에서 매우 뛰어난 공법으로 주목 받고 있으나 그 설계 및 시공에 있어 아직도 불확실한 요소를 내포하고 있다. 특히 최근에는 PSC 박스 거더교에서 교폭을 늘리고 자중을 줄이기 위해 콘크리트 충진 FRP 스트럿을 설치하는 공법이 다수 시공되고 있다. 본 연구에서는 이러한 대상교량에 대해 현장시험을 실시하여 교량시스템에서의 콘크리트 충진 FRP 스트럿 거동을 분석하는데 목적이 있다. 특히 전자기파 간섭에 면역이 우수한 광센서인 FBG 센서를 기반으로 하는 계측을 실시하여 잡음이 없는 우수한 결과를 성공적으로 획득하였다. 그 결과 FRP 스트럿은 하중 재하 위치와 속도에 관계없이 압축응력 상태에 존재하고 있으며 횡방향 거동에 지배되고 있음을 확인하였다.

• Journal of Advanced Navigation Technology
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• v.17 no.3
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• pp.354-360
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• 2013

A stereo vision analysis was performed for motion and depth control of unmanned vehicles. In stereo vision, the depth information in three-dimensional coordinates can be obtained by triangulation after identifying points between the stereo image. However, there are always triangulation errors due to several reasons. Such errors in the vision triangulation can be alleviated by careful arrangement of the camera position and orientation. In this paper, an approach to the determination of the optimal position and orientation of camera is presented for unmanned vehicles.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.4131-4138
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• 2012

In this paper, we propose a Pedestrian Position Information System(PPIS) using low-cost inertial sensors in GPS-disabled area. The proposed scheme estimates the attitude/heading angle and step detection of pedestrian. Additionally, the estimation error due to the inertial sensors is mitigated by using additional sensors. We implement a portable hardware module to evaluate performance of the proposed system. Through the experiments in indoor building, the estimation error of position information was measured as 2.4% approximately.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.2
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• pp.94-101
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• 2009

We introduce a user authentication system using distance estimation and a simple challenge response protocol based on a pre-established key. Using the time difference of arrival between an RF signal and an ultrasonic signal, an authenticator verifies if a user's authentication token is within its threshold distance, and it also verifies if the token's response to its random challenge is valid. We implement our authentication system and we analyze the success rates for authentication according to the variations in the distances and facing angles between the authenticator and the token. Our experimental results show that the token is authenticated with very high probability in reasonable settings.