• 한국멀티미디어학회논문지
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• 제5권3호
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• pp.272-280
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• 2002

본 논문은 스테레오 비젼 시스템을 이용하여 이동 객체를 추출하고 그 객체까지의 거리를 측정하는 방법을 제안하였다. 이동 객체에 대한 이동 성분은 화소 단위의 정합을 통하여 추출하였으며, 적응형 임계값은 영상의 밝기 변화를 제거하는데 효과적으로 대처할 수 있었다. 이동 객체까지의 거리는 평행식 카메라를 적용한 스테레오 비전 시스템을 사용하여 측정하였다. 실험 결과 이동 객체에 대한 거리측정 오차가 평균 1%로 나타남으로써 제안한 알고리즘을 이용한 이동 객체의 거리측정 가능성을 제시하였다.

• 한국통신학회논문지
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• 제37권6C호
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• pp.453-461
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• 2012

본 논문에서는 진폭 변조 거리 측정 시스템에 적용 가능한 개선된 위상 추정 기법을 제안한다. 기존 위상 측정 방법은 이동 목표물의 도플러 천이에 의해 위상 측정 오차가 발생한다. 제안된 위상 추정 기법은 도플러 천이에 대해 적응 도플러 보정(Adaptive Doppler Correction)을 사용하여 위상 추정 오차를 보정하므로 거리 측정 정확도를 향상 시킬 수 있다. 모의실험 결과 도플러 주파수 천이 보정은 기존 방식보다 94.7% 향상된 성능을 보이며, 거리 측정 정확도는 50%로 향상되었다. 음향 수조에서는 오차가 7.7cm로 추정되어 해양 환경에서 음파를 이용하여 거리 추정에도 적용 가능함을 확인하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권8호
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• pp.4227-4240
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• 2019

In this paper, we present our proposed magnetic induction based wireless communication system. The proposed system is designed to perform communication as well as distance measurement in underground environments. In order to improve the communication quality, we propose and implement the adaptive channel compensation technique. Based on the fact that the channel may be fast time-varying, we keep track of the channel status each time the data is received and accordingly compensate the channel coefficient for any change in the channel status. By using the proposed compensation technique, the developed platform can reliably communicate over distances of 10m while the packet error rate is being maintained under 5%. We also implement the distance measurement block that is useful for various applications that should promptly estimate the location of nearby nodes in communication. The distance between two nodes in communication is estimated by generating a table describing pairs of the magnetic signal strength and the corresponding distance. The experiment result shows that the platform can estimate the distance of a node located within 10m range with the measurement error less than 50cm.

• 제어로봇시스템학회논문지
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• 제17권9호
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• pp.947-953
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• 2011

Radome aberration error causes degradation of miss distance as well as stability of high maneuver missile system with RF seeker. A study about radome compensation method is important in this kind of missile system design. Several kinds of methods showed good compensation performance in their paper. Proposed adaptive Particle filter estimates line of sight rate excluding the radome induced error. This paper shows effectiveness of adaptive Particle filter as compensation method of radome aberration error. Robust performance of this filter depends on external aiding measurement, target acceleration. Tuning of system error covariance can make this filter unsensitive against the error of target acceleration information. This paper demonstrates practical usage of adaptive Particle filter for reducing miss distance and increasing stability against disturbance of radome aberration error through performance analysis.

• 한국인터넷방송통신학회논문지
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• 제18권5호
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• pp.147-153
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• 2018

저전력 블루투스(BLE; Bluetooth Low Energy) 기술을 사용한 비콘은 실외에서만 위치 측위가 가능한 GPS(Global Positioning System)와 달리 실내에서도 위치 파악이 가능하다. 비콘을 사용한 실내 거리 측정에는 RSSI(Received Signal Strength Indication)값이 핵심 요소인데 그에 반해 RSSI값은 여러 환경요소로부터 영향을 받기 때문에 예측된 거리와 실제 거리의 오차가 크게 나타난다. 이러한 이슈를 다루기 위해 비콘을 사용한 ANN(Artificial Neural Network)기반 적응형 거리 측정을 제안한다. 먼저 RSSI의 잡음을 줄이기 위해 확장 칼만 필터와 신호 안정화 필터를 사용한 전처리 과정을 거친다. 그리고 각각 특정 학습 데이터 셋을 가진 다층 ANN들은 학습을 거치게 된다. 결과에서는 평균오차 0.67m를 보여주고, 0.78의 precision을 보여준다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.305-307
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• 2003

This paper presents an apparent impedance calculation procedure for distance relaying of transmission line involving FACTS (Flexible AC Transmission System) devices, particularly the UPFC (Unified Power Flow Controller), between Kangjin and Jangheung in Korea. With the changes of UPFC's parameters, the measurement and protective range (trip boundaries) of the adaptive distance relay can also be changed. So, it is the most important part in the field of system protection to analyze the operating characteristic of relaying system. The presence of UPFC significantly affects the trip boundaries which are also adversely affected by fault resistance combined with remote end infeed. This paper presents the apparent impedance calculations and the distance relay setting characteristics for faults involving the UPFC in the KEPCO system.

• Current Optics and Photonics
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• 제2권4호
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• pp.348-355
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• 2018

How to measure the creepage distance of an insulator quickly and accurately is a problem for the power industry at present, and the noticeable concern is that the high voltage insulation equipment cannot be measured online in the charged state. In view of this situation, we develop an on-line measurement system of creepage distance for high voltage insulators based on binocular stereo vision. We have proposed a method of generating linear structured light using a conical off-axis mirror. The feasibility and effect of two ways to solve the interference problem of strong sunlight have been discussed, one way is to use bandpass filters to enhance the contrast ratio of linear structured light in the images, and the other way is to process the images with adaptive threshold segmentation and feature point extraction. After the system is calibrated, we tested the measurement error of the on-line measurement system with a composite insulator sample. Experimental results show that the maximum relative error is 1.45% and the average relative error is 0.69%, which satisfies the task requirement of not more than 5% of the maximum relative error.

• Journal of Electrical Engineering and Technology
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• 제8권5호
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• pp.1188-1193
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• 2013

In content based image retrieval (CBIR) system, the images are represented based upon its feature such as color, texture, shape, and spatial relationship etc. In this paper, we propose a MRI Image Retrieval using wavelet transform with mahalanobis distance measurement. Wavelet transformation can also be easily extended to 2-D (image) or 3-D (volume) data by successively applying 1-D transformation on different dimensions. The proposed algorithm has tested using wavelet transform and performance analysis have done with HH and $H^*$ elimination methods. The retrieval image is the relevance between a query image and any database image, the relevance similarity is ranked according to the closest similar measures computed by the mahalanobis distance measurement. An adaptive similarity synthesis approach based on a linear combination of individual feature level similarities are analyzed and presented in this paper. The feature weights are calculated by considering both the precision and recall rate of the top retrieved relevant images as predicted by our enhanced technique. Hence, to produce effective results the weights are dynamically updated for robust searching process. The experimental results show that the proposed algorithm is easily identifies target object and reduces the influence of background in the image and thus improves the performance of MRI image retrieval.

• 한국항해항만학회지
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• 제31권7호
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• pp.563-568
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• 2007

In this paper, an adaptive neural network controller and its application to automatic berthing control of ship is presented. The neural network controller is trained online using adaptive interaction technique without any teaching data and off-line training phase. Firstly, the neural networks used to control rudder and propeller during automatic berthing process are presented. Secondly, computer simulations of automatic ship berthing are carried out in Pusan bay to verify the proposed controller under the influence of wind disturbance and measurement noise. The results of simulation show good performance of the developed berthing control system.

• 자동차안전학회지
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• 제14권2호
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• pp.57-69
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• 2022

Recently, as interest in self-driving cars has increased worldwide, research and development on the Advanced Driver Assist System is actively underway. Among them, the purpose of Adaptive Cruise Control (ACC) is to minimize the driver's driving fatigue through the control of the vehicle's longitudinal speed and relative distance. In this study, for the research of the ACC test in the real environment, the real-road test was conducted based on domestic-road test scenario proposed in preceding study, considering ISO 15622 test method. In this case, the distance measurement method using the dual camera was verified by comparing and analyzing the result of using the dual camera and the result of using the measurement equipment. As a result of the comparison, two results could be derived. First, the relative distance after stabilizing the ACC was compared. As a result of the comparison, it was found that the minimum error rate was 0.251% in the first test of scenario 8 and the maximum error rate was 4.202% in the third test of scenario 9. Second, the result of the same time was compared. As a result of the comparison, it was found that the minimum error rate was 0.000% in the second test of scenario 10 and the maximum error rate was 9.945% in the second test of scenario 1. However, the average error rate for all scenarios was within 3%. It was determined that the representative cause of the maximum error occurred in the dual camera installed in the test vehicle. There were problems such as shaking caused by road surface vibration and air resistance during driving, changes in ambient brightness, and the process of focusing the video. Accordingly, it was determined that the result of calculating the distance to the preceding vehicle in the image where the problem occurred was incorrect. In the development stage of ADAS such as ACC, it is judged that only dual cameras can reduce the cost burden according to the above derivation of test results.