• Journal of Communications and Networks
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• v.18 no.3
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• pp.397-410
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• 2016

This paper proposes a novel cooperative localization method for distributed wireless networks in 3-dimensional (3D) global positioning system (GPS) denied environments. The proposed method, which is referred to as hybrid ellipsoidal variational algorithm (HEVA), combines the use of non-parametric belief propagation (NBP) and variational Bayes (VB) to benefit from both the use of the rich information in NBP and compact communication size of a parametric form. InHEVA, two novel filters are also employed. The first one mitigates non-line-of-sight (NLoS) time-of-arrival (ToA) messages, permitting it to work well in high noise environments with NLoS bias while the second one decreases the number of calculations. Simulation results illustrate that HEVA significantly outperforms traditional NBP methods in localization while requires only 50% of their complexity. The superiority of VB over other clustering techniques is also shown.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.485-489
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• 2006

In last decades, several linearization methods for the AOA measurements have been proposed, for example, Gauss-Newton method and closed-form solution. Gauss-Newton method can achieve high accuracy, but the convergence of the iterative process is not always ensured if the initial guess is not accurate enough. Closed-form solution provides a non-iterative solution and it is less computational. It does not suffer from convergence problem, but estimation error is somewhat larger. This paper proposes a self-tuning weighted least square AOA algorithm that is a modified version of the conventional closed-form solution. In order to estimate the error covariance matrix as a weight, two-step estimation technique is used. Simulation results show that the proposed method has smaller positioning error compared to the existing methods.

• Journal of the Korean Institute of Navigation
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• v.12 no.3
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• pp.1-21
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• 1988

A Satellite -aided search and rescue system is expected for its many advantage of global coverage, instantaneousness and low cost. In this paper, a calculation method is proposed , by which a position of distress can be determined with doppler frequency received through an orbital satellite. First, an algorithm and program is developed for calculating the position of distress with the received doppler frequency of EPIRB(Emergency Position Indicating Radio Beacon) with the least square method. Then, position error caused by the drift of the transmitting frequency is evaluated. The evaluation is made by the simulation using NNSS satellite orbital elements and varying position of EPIRB, numbers of Doppler data and magnitudes of various errors. As the result, the availability of this program for a satellite-aided search and rescue system is confirmed and the bounds of expected positioning accuracy is clarified.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04a
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• pp.565-567
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• 2001

교류의 증대와 활동영역의 증가로 인하여 사용자의 위치를 결정하고, 최적의 거리를 검색하는 등의 필요성에 의해 위치결정을 위한 방법과 시스템은 많은 발전을 거듭해 왔다. 특히 미해군항공위성시스템에서 시작하여 개발되어진 GPS 시스템은 현재 많은 분야에서 사용되고 있다. 또한 DGPS의 개발로 인하여 더욱 고정밀의 위치 결정이 가능하게 되었다. 본 논문에서는 이러한 위치결정의 기본원리인 TDOA를 응용하여 단위 지역내에서 사용되어질 수 있는 경제적인 시스템의 구조를 제안하고, 위치를 결정할 수 있는 여러 가지 방법을 분석하여 합리적인 위치 결정 알고리즘을 개발하여 그 효율성을 검증하였다.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.1
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• pp.49-58
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• 2003

Compared with generic GPS receiver, post-processing software GPS receiver has many advantages for high dynamic vehicle tracking. It has the advantage of the application of various tracking algorithms and aiding schemes. The post-processing system observes the carrier phase measurement data from the recorded GPS signals, detects and isolates the cycle slip. The observed carrier phase data and the raw data of the reference station are processed by carrier phase DGPS scheme. And the integer ambiguity resolution algorithm is used for resolving single frequency carrier phase ambiguity. The results of static and real flight test are presented and show that the proposed GPS translator processing system satisfies submeter accuracy.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.725-727
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• 2010

For simulation of Boat motion, pitch, motion element of roll and yaw direction could simulated. The combination of the marine use various multi sensor surveillance system technology with the development of servo motion control algorithm and gyro sensor in six freedom motion is implemented to analyze the movement response. The stabilization of the motion control is developed and Nano driving Precision Pan-Tilt/Gimbal system is obtained from the security positioning cameras with ultra high speed device is used to carry out the exact behavior of the device.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.930-932
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• 2003

For this study we used a CCD video camera to capture the pavement image information via the computer. During investigation processing, the CCD video camera captured 10${\sim}$30 images per second. If the vehicle velocity is too fast, the collected images will be duplicated and if the velocity is too slow there will be a gapped between images. Therefore, in order to control the efficiency of the image grabber we should add accessory tools such as the Differential Global Positioning System (DGPS) and odometer. Furthermore, Kalman Filtering can also solve these problems. After the CCD video camera captured the pavement images, we used the Least-Squares method to eliminate images of gradation which have non-uniform surfaces due to the illumination at night. The Fuzzy Entropy method calculates images of threshold segments and creates binary images. Finally, the Object Labeling algorithm finds objects that are cracks or noises from the binary image based on volume pixels of the object. We used these algorithms and tested them, also providing some discussion and suggestions.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.39-41
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• 1995

The inherent performance of Ultrasonic Motor(USM) which is on of highlighted a directly-driven positioning servo motor/actuator. In this paper, the speed of control USM based on neural network control. The neural network control can roughly be classified as the direct control and indirect control schemes. An indirect control scheme is adopted for Ultrasonic Motor speed control. A back propagation algorithm is used to train neural network controller. The Simulation results show that this neural network control system can provide good dynamical responses.

• Annual Conference of KIPS
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• 2015.10a
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• pp.482-484
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• 2015

대표적인 위치기반 기술인 GPS는 건물 내부와 같이 실내에서의 위치추정이 거의 불가능하다. 따라서 실내 측위의 방안으로 BlueTooth 4.0LE 기반의 장치인 비콘(Beacon)을 활용하여 실내 GPS의 역할을 수행하도록 하는 기법이 활용되고 있다. 그러나, 비콘의 거리측정에 사용되는 RSSI의 문제점으로 인해, 위치추정의 정확도가 급격히 저하되는 문제점을 가지고 있다. 본 논문에서는 개선된 위치선정 알고리즘을 통하여 오차율을 줄여, 정밀한 위치 추정이 가능한 알고리즘을 제안하였다.

• Annual Conference of KIPS
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• 2015.10a
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• pp.1205-1207
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• 2015

Fingerprinting 방식에서 KNN은 WLAN 기반 실내 측위에 가장 많이 적용되고 있지만 KNN의 성능은 k개의 이웃 수와 RP의 수에 따라 민감하다. 논문에서는 KNN 성능을 향상시키기 위해 ANN 군집화를 적용한 KNN과 ANN을 혼합한 알고리즘을 제안하였다. 제안한 알고리즘은 신호잡음비 데이터를 KNN 방법에 적용하여 k개의 RP을 선택한 후 선택된 RP의 신호잡음비를 ANN에 적용하여 k개의 RP를 군집하여 분류한다. 실험 결과에서는 위치 오차가 2m 이내에서 KNN/ANN 알고리즘이 KNN 알고리즘보다 성능이 우수하다.