• 한국생산제조학회지
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• 제21권5호
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• pp.747-754
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• 2012

A solar power generator is usually installed outdoors and it is exposed to extreme environments such as snow weight and wind loading. The solar tracker structure should be designed to have sufficient stiffness and strength against such loads. In this paper, simulations are performed by varying the parameters such as wind directions, wind speeds and the pose of the solar panel to evaluate the effects of extreme wind on solar tracker. As the effects of wind load, maximum displacement and maximum equivalent stress in the solar tracker are calculated. Finite element stress analysis is carried out by using the pressure distribution that is obtained by prior wind load analysis due to the flow around the solar tracker. The stress analysis of solar tracker to check and/or improve structural robustness provides some useful instructions for structural design or revision of solar tracker.

• 한국항공우주학회지
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• 제37권5호
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• pp.470-475
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• 2009

본 논문은 헤드 트랙커(Head Tracker) 시스템에 패턴 매칭을 적용한 연구이다. 제안하는 알고리즘은 패턴을 통하여 헤드 트랙커의 초기자세를 빠르고 쉽게 획득하는 것이다. 광학 방식 헤드 트랙커는 적외선 LED(특징점)를 헬멧에 부착하고, 스테레오 카메라로 영상을 획득한다. 영상 분석시 발생하는 특징점간 거리 오차율을 바탕으로 패턴을 이루며 특징점을 부착한다. 특징점간 거리를 이용해 패턴 분석을 하고, 획득된 패턴을 바탕으로 특징점에 고유 번호를 부여한다. 맵 데이터와 특징점 고유 번호를 비교함으로써 헤드 트랙커의 초기자세를 추정한다.

• 한국컴퓨터정보학회논문지
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• 제21권11호
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• pp.49-57
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• 2016

In this paper, we propose the novel tracking method which uses the weighted discriminative correlation filter (DCF). We also propose the PSPR instead of conventional PSR as tracker performance evaluation method. The proposed tracking method uses multiple DCF to estimates the target position. In addition, our proposed method reflects more weights on the correlation response of the tracker which is expected to have more performance using PSPR. While existing multi-DCF-based tracker calculates the final correlation response by directly summing correlation responses from each tracker, the proposed method acquires the final correlation response by weighted combining of correlation responses from the selected trackers robust to given environment. Accordingly, the proposed method can provide high performance tracking in various and complex background compared to multi-DCF based tracker. Through a series of tracking experiments for various video data, the presented method showed better performance than a single feature-based tracker and also than a multi-DCF based tracker.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.165-168
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• 2004

This paper propose a target tracker using phase correlation. The tracker consist of a pre-processing module, a translation estimation module based on phase correlation, a fine motion estimation module applied when confidence rate could not fulfill a threshold value and a reference image update module. The fine motion estimation module measure the shift, rotation and scale of input image compared to reference using Fourier-Mellin transform. Proposed tracker was tested its accuracy and robustness using some real indoor and outdoor image sequences.

• 한국항공우주학회지
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• 제49권3호
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• pp.243-249
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• 2021

별추적기는 우주공간에서 미세한 별 빛을 감지한 후 저장된 별 목록과 비교하여 관성좌표계상에서 위성의 자세 정보를 제공한다. 별 이외에 태양이나 지구와 같은 다른 빛이 광학계(OH : Optical Head)로 들어가게 될 경우 별을 인식할 수 없음으로 별추적기를 운영할 수 없다. 특히, 태양과 같은 강한 빛이 들어올 경우 별추적기 운영뿐 아니라 성능에도 영향을 미친다. 별추적기의 태양 차폐각(SEA : Sun Exclusion Angle)은 별추적기의 성능을 결정하는 중요한 요소 중 하나이다. 본 논문에서는 별추적기의 태양 차폐각에 대한 검증을 수행하였다. 태양 차폐각 검증을 위해서 별추적기의 태양 차폐 시간을 예측하였으며 실제 천리안 2A호 별 추적기에서 발생한 태양 차폐 시간과 비교하였다. 또한, 광학계에 태양에 의한 차폐가 발생할 경우 별추적기가 정상적으로 동작하는지에 대한 분석을 수행하였다. 분석 결과 별추적기는 성능 요구사항인 26° 이내에서 태양 차폐가 발생하였으며 태양 차폐가 발생할 경우에도 정상 동작함을 확인하였다.

• ETRI Journal
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• 제30권2호
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• pp.338-340
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• 2008

In this letter, we propose a novel approach to detecting and tracking apartment buildings for the development of a video-based navigation system that provides augmented reality representation of guidance information on live video sequences. For this, we propose a building detector and tracker. The detector is based on the AdaBoost classifier followed by hierarchical clustering. The classifier uses modified Haar-like features as the primitives. The tracker is a motion-adjusted tracker based on pyramid implementation of the Lukas-Kanade tracker, which periodically confirms and consistently adjusts the tracking region. Experiments show that the proposed approach yields robust and reliable results and is far superior to conventional approaches.

• International Journal of Aeronautical and Space Sciences
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• 제3권2호
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• pp.88-94
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• 2002

This paper describes attitude determination algorithm for the low earth orbit(LEO) spacecraft using stellar inertial sensors. The cascaded gyro/star tracker extended Kalman filter is constructed to fuse two sensor data. And then the smoothing of the measurement are proposed for an unreasonable jump of star tracker. The smoothing algorithm for the rejection of star tracker error jumps is designed by scalar adaptive filter. The proposed algorithms operate to process the measurement of gyro/star tracker Kalman filter, therefore, it is comparatively simple to apply these methods to other integration systems. Simulations to gyro/star tracker integrated system show that the proposed method is effective.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.506-509
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• 2005

An adaptive ${\alpha}-{\beta}$ tracker is proposed for tracking maneuvering targets with a track-while-scan radar system. The tracker gain is updated on-line corresponding to the adjusted process noise variance which is obtained via time averaging of the process over a sliding window. The adjusted process noise variance is used to compute the maneuverability index for the tracker gain based on the steady-state Kalman filter equation for each epoch. It is shown via simulation that the proposed approach provides robust and accurate position estimates during the target maneuver while the performance of the conventional ${\alpha}-{\beta}$ tracker is shown much degraded.

• International Journal of Aeronautical and Space Sciences
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• 제3권1호
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• pp.39-49
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• 2002

This paper presents a robust tracker design method that is specific to the trajectories of target aircraft. This method assumes that representative trajectories of the target aircraft are available. The exact trajectories known to the tracker enables the incorporation of the exact data in the tracker design instead of the measurement data. An estimator is designed to have acceptable performance in tracking a finite number of different target trajectories with a capability to trade off the mean and maximum errors between the exact trajectories and the estimated or predicted trajectories. Constant estimator gains that minimize the cost functions related to the estimation or prediction error are computed off-line from an iterative algorithm. This tracker design method is applied to the longitudinal motion tracking of target aircraft.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.220-220
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• 2009

In case of favourable irradiation conditions, the ratio of irradiation to the total irradiation went up and then the irradiation increased in the area with high angle of inclination. The study showed that on a clear day with the irradiation of more than $800[W/m^2]$, the pattern of alternating current power change in the fixed system was similar with that in the single-axis tracker. On the contrary, in case of unfavourable irradiation conditions, the ratio of diffuse irradiation to the total irradiation went up and then the horizontal irradiation increased. In the demo system, the fixed system, the single-axis tracker and the dual-axis tracker all had low generation power and similar generation pattern with each other. The study showed the generation power varied with the irradiation in the fixed system, while in the single-axis tracker and the dual-axis tracker, the amount of the generation power variation was much more than the irradiation variation. The demo system was operated from 11:00 AM to 2:00 PM for generating power, during which time, 46[%] to 56[%] of the total generation power was produced. In this study. the generation power was increased by 147[%] in the fixed system, by 136[%] in the single-axis tracker, and by 164[%] in the dual-axis tracker, and the pattern of generation power was similar with the generation power variation in the situation where the irradiation increased by 140[%] in the spring with plenty of insolation. The alternating current power was more sensitive to variation of the irradiation than to that of the surface temperature of a module. The variation of the irradiation had a more positive effect on the generation power than the type of array.