• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.8C
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• pp.731-740
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• 2012

To offer indoor location-aware services, the needs for efficient and accurate indoor localization system has been increased. In order to meet these requirement, we presented the BLIDx(Bidirectional Location ID exchange) protocol that is efficient localization system based on sensor network. The BLIDx protocol can cope with numerous mobile nodes simultaneously but the precision of the localization is too coarse because that uses cell based localization method. In this paper, in order to compensate for these disadvantage, we propose the fingerprint overlapping method by modifying a fingerprinting methods in WLAN, and localization system using proposed method was designed and implemented. Our experiments show that the proposed method is more accurate and robust to noise than fingerprinting method in WLAN. In this way, it was improved that low location precision of BLIDx protocol.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.246-246
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• 2004

현재 비구면렌즈를 만들기 위해서는 다양한 방법이 있다. Glass종류의 가공시 초정밀 절삭가공기(DTM)에서 가공하거나 정밀 연삭기를 가지고 가공하게 된다. 이 과정에서 렌즈 표면에 공구 흔적이나 표면거칠기 개선을 위해 연마작업을 하게 되는데, 사용하는 장비가 폴리싱 머신이다. 축대칭인 폴리싱머신의 경우 X, Z, $\theta$로 동시 3축제어가 가능하다. 하지만 이 장비의 경우 연마에서 원하는 형상정밀도와 표면거칠기를 얻기 위해 각축들의 위치정밀도와 분해능이 높은 부품을 사용하여 기계자체가 고가라는 점이 단점으로 작용한다.(중략)

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1990.04a
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• pp.46-52
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• 1990

위치결정 정도의 향상과 robot arm의 경량화및 운동의 고속화의 요구에따라 비교적 가벼운 중량에 비해 상대적으로 큰 하중을 다룰수 있으며 고속 동작도 가능한 우연성있는 robot arm의 동장이 필요하게 되었다. 본 연구에서는 ballscrew system으로 구성되어 병진운동을 하는 탄성 arm 선단의 위치를 제어하는 이론적인 해석을 하고, 실제의 실험장치를 통하여 선단의 위치를 제어 하므로써 system의 제어특성을 찾고자 한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.316-316
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• 2004

이동로봇이 자율항해를 하기 위해서는 위치추적 즉, 지금까지의 정보와 현재의 정보로부터 작업환경내의 어디에 로봇이 위치해 있는가를 알아내는 것이다 따라서 위치추적은 로봇이 어디로 가고 있는가 라는 물음과 어떻게 목표점에 도달할 것인가라는 물음에 대한 답의 기본이 된다는 의미에서 자율항해에서 가장 중요한 기능이라고 할 수 있다. 초음파 센서를 이용한 위치 추적은 그리드형태의 지도를 이용하는 방법과 물체의 형상을 기준으로 하는 방법이 있다.(중략)

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.9-9
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• 1997

• Journal of the Korean Society for Precision Engineering
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• v.20 no.5
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• pp.22-28
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• 2003

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.5
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• pp.667-672
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• 2011

This paper presents to study the sensor fusion of positioning sensors using UKF(unscented Kalman filter) for positioning accuracy improvement of AGV(automatic guided vehicle). The major guidance systems for AGV are wired guidance and magnetic guidance system. Because they have high accuracy and fast response time, they are used in most of the FMS(flexible manufacturing system). However, they had weaknesses that are high maintenance cost and difficult of existing path modification. they are being changed to the laser navigation in recent years because of those problems. The laser navigation is global positioning sensor using reflecters on the wall, and it have high accuracy and easy to modify the path. However, its response time is slow and it is influenced easily by disturbance. In this paper, we propose the sensor fusion method of the laser navigation and local sensors using UKF. The proposed method is improvement method of accuracy through error analysis of sensors. For experiments, we used the axle-driven forklift AGV and compared the positioning results of the proposed method with positioning results of the laser navigation. In experimental result, we verified that the proposed method can improve positioning accuracy about 16%.

• Korean Journal of Remote Sensing
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• v.27 no.1
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• pp.25-31
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• 2011

Precise control of antenna position is very critical in ArcSAR system which uses an arc-rail as a platform for the antenna movement instead of linear rail. In order to minimize the antenna positional error, we improved the motion driving system and applied a newly developed motion control S/W which utilizes the real time antenna position information from magnetic linear scale and encoder. The experimental results showed that the rotational RMS error was reduced to $0.0062^{\circ}$ from $0.0432^{\circ}$. In terms of antenna positional RMS error for the arm length of 3m, it was reduced to 0.324mm from 2.262mm. It is expected that the ArcSAR system can be used to monitor the sub-millimetric displacement of terrain and structural targets.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.3
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• pp.249-258
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• 2012

In this study, the epoch adjustment model was developed to correct GPS precise point positioning result to be suitable for the current geodetic datum of Korea which is tied at past epoch statically. The model is based on the formula describing crustal movements, and the formula is composed of several parameters. To determine the parameters, the data gathered at 14 permanent GPS stations for 10 years, from 2000 to 2011, were processed using GIPSY-OASIS II. It was possible to determine the position of permanent GPS stations with an error range of 16mm and the position of check points with an error range of 12mm by appling the model to GPS precise point positioning result. It is considered that more precise model could be calculated by using GPS data of more permanent GPS stations.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.294-301
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• 2016

Recently, the solar tracker has been used to improve the efficiency of solar energy. Solar tracking technologies are classified into the sensor-based method, the program-based method, and the hybrid method. Solar trackers using an AC motor and CdS sensor are low in cost, but the precision of the positions is low, owing to the inertia of the motor and the scattering of sunlight. To compensate for the low precision, we implement a CdS sensor module and propose an AC motor control method using error value. To evaluate the performance of the solar tracker, we implemented a solar water heater. From the experimental results, the solar tracker can achieve ${\pm}2mm$ accuracy for sun, can satisfy ${\pm}15mm$ as a limited error value, and provides a 32% performance enhancement in KSB8202 criteria.