• 제어로봇시스템학회논문지
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• 제21권4호
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• pp.349-355
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• 2015

Underwater robots generally show better performances for tasks than humans under certain underwater constraints such as. high pressure, limited light, etc. To properly diagnose in an underwater environment using remotely operated underwater vehicles, it is important to keep autonomously its own position and orientation in order to avoid additional control efforts. In this paper, we propose an efficient method to assist in the operation for the various disturbances of a remotely operated vehicle for the diagnosis of underwater structures. The conventional AHRS-based bearing estimation system did not work well due to incorrect measurements caused by the hard-iron effect when the robot is approaching a ferromagnetic structure. To overcome this drawback, we propose a sensor fusion algorithm with the camera and AHRS for estimating the pose of the ROV. However, the image information in the underwater environment is often unreliable and blurred by turbidity or suspended solids. Thus, we suggest an efficient method for fusing the vision sensor and the AHRS with a criterion which is the amount of blur in the image. To evaluate the amount of blur, we adopt two methods: one is the quantification of high frequency components using the power spectrum density analysis of 2D discrete Fourier transformed image, and the other is identifying the blur parameter based on cepstrum analysis. We evaluate the performance of the robustness of the visual odometry and blur estimation methods according to the change of light and distance. We verify that the blur estimation method based on cepstrum analysis shows a better performance through the experiments.

• 방송공학회논문지
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• 제8권2호
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• pp.198-203
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• 2003

본 논문에서는 멀티미디어 데이터에 존재하는 입술의 움직임(영상언어)과 음성을 함께 이용하여 음성의 끝점을 정확히 추정하는 방법과 이를 기반으로 한 음성인식 시스템을 제안한다. 잡음 섞인 음성의 끝점추정 방법은 다음과 같다. 각 테스트 단어에 대하여 영상언어를 이용한 끝점과 깨끗한 음성을 이용한 끝점을 각각 구한 후 이것들의 차이를 계산한다. 이 차이에 영상언어 끝점을 더하여 잡음 섞인 음성의 끝점으로 추정한다. 이와 같은 끝점(즉, 음성구간)의 추정방법을 인식기에 적용한다. 동일한 구간의 음성이 인식기의 각 단어모델에 입력되는 기존의 인식 방법과는 달리, 새로운 인식기에서는 각 단어별로 추정된 서로 다른 구간의 음성이 각 해당단어모델에 입력된다. 제안된 방식을 모의실험 한 결과, 음성잡음의 크기에 관계없이 정확한 끝점을 추정 할 수 있었으며, 그 결과 약 8% 정도의 인식률 향상을 이루었다.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제6권2호
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• pp.161-166
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• 2006

Localization of mobile agent within a sensing network is a fundamental requirement for many applications, using networked navigating systems such as the sonar-sensing system or the visual-sensing system. To fully utilize the strengths of both the sonar and visual sensing systems, This paper describes a networked sensor-based navigation method in an indoor environment for an autonomous mobile robot which can navigate and avoid obstacle. In this method, the self-localization of the robot is done with a model-based vision system using networked sensors, and nonstop navigation is realized by a Kalman filter-based STSF(Space and Time Sensor Fusion) method. Stationary obstacles and moving obstacles are avoided with networked sensor data such as CCD camera and sonar ring. We will report on experiments in a hallway using the Pioneer-DX robot. In addition to that, the localization has inevitable uncertainties in the features and in the robot position estimation. Kalman filter scheme is used for the estimation of the mobile robot localization. And Extensive experiments with a robot and a sensor network confirm the validity of the approach.

• Journal of the Korean Data and Information Science Society
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• 제22권5호
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• pp.885-893
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• 2011

영상자료센터는 필름이나 디지털영상물과 같은 영상자료의 보존을 위한 시설로서 현재 건립사업이 고려되고 있다. 본 연구는 국내외 문헌에서 비시장재의 주된 가치평가기법으로 사용되고 있는 조건부가치평가법 (Contingent Valuation Method, CVM)을 이용하여 일반 국민이 영상자료센터 건립사업에 부여하는 경제적 편익을 추정한다. 분석에 사용된 설문조사자료는 7대 광역시에서 일대일 개인면접으로 수집되었으며, 추정모형은 로짓모형이 사용되었다. 분석결과, 년 지불의사액으로 평가된 경제적 편익은 가구당 년 평균 8,958원으로 나타났다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2004년도 춘계종합학술대회
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• pp.434-438
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• 2004

This paper has proposed presumable method of ergonomics estimate index from evoked potential of visual stimulation for establishment a fixed ergonomics estimate index. The proposed method presumes continuance time and amplitude of ergonomics using prony method. Band characteristic of alpha and beta band, and that of background and evoked potential was analyzed using FFT method. And, that were presumed continuance time and amplitude of ergonomics using porny method. As a result of that proposed method presumed band characteristic, continuance time and amplitude of ergonomics, classification of ergonomics of impatient, rage and fear were practicable.

• 한국조경학회지
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• 제35권2호통권121호
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• pp.55-63
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• 2007

The purpose of this study is to create a planting design for progressive realization. For this, visual preferences as measured via questionnaire were evaluated by the Scenic Beauty Estimation(SBE) and paired comparison methods. The results can be summarized as follows. Through photo observation, the average visual blockage ratio was 38% and the range of degree of the visual blockage ratio was $30{\sim}50%$. The sketch simulation and filtered pattern received the highest preference score and fumed out to be the most practical pattern out of all the patterns evaluated. Also, in the sketch simulation, the high preference values were observed for a distance of 9 to 12m from the view point to the blockage tree with a D/H ratio of 2. The preference score significantly decreased with the increase of the visual blockage ratio having a turning point at $30{\sim}35%$ of the visual blockage ratio, even though the distance parameters were more important than the visual blockage ratio in the scores. An outstanding view must be handled properly to be preserved or accentuated. Framed, open, enclosed, screened or filtered pattern views should be completely revealed only from their best vantage point, not given away at first glimpse. It this sense, parallax spatial beauty with trees could be improved through the visual aspects of plan arrangements and seems to be an effective design technique for landscape planning and planting design.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(4)
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• pp.35-38
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• 2000

The method of Content-based Triangular Mesh Image representation in moving pictures makes better performance in prediction error ratio and visual efficiency than that of classical block matching. Specially if background and objects can be separated from image, the objects are designed by Irregular mesh. In this case this irregular mesh design has an advantage of increasing video coding efficiency. This paper presents the techniques of mesh generation, motion estimation using these mesh, uses image warping transform such as Affine transform for image reconstruction, and evaluates the content based mesh design through computer simulation.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1749-1752
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• 2005

For online high accurate reconstruction of an object from an visual information, a linear reconstruction method for multiple images is popular. Basically this method needs many cameras or many different screen shots from different view points. This method, however, has the benefit of less calculation and is adequate for a real time application by comparing other popular method. In this paper, online reconstruction system using more than three cameras is treated. An evaluation method of cameras' position, and of the number is derived for the linear reconstruction method. To decrease errors that are caused from skew of lens, positional error between corresponding points is taken into consideration on the evaluation. The proposed evaluation method enables estimation of the adequate number of cameras and then of feasible view locations. Additionally, repeating search of epipolar lines enables estimation of the hidden point. Comparing with result of an average error analysis, it was confirmed that the proposed methods works effectively.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1121-1125
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• 2003

In this paper we deal with visual servoing that can control a robot arm with a camera using information of images only, without estimating 3D position and rotation of the robot arm. Here it is assumed that the robot arm is calibrated and the camera is uncalibrated. We use a pinhole camera model as the camera one. The essential notion can be show, that is, epipolar geometry, epipole, epipolar equation, and epipolar constrain. These play an important role in designing visual servoing. For easy understanding of the proposed method we first show a design in case of the calibrated camera. The design is constructed by 4 steps and the directional motion of the robot arm is fixed only to a constant direction. This means that an estimated epipole denotes the direction, to which the robot arm translates in 3D space, on the image plane.

• 제어로봇시스템학회논문지
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• 제21권4호
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• pp.321-329
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• 2015

This paper addresses a new algorithm for a stereo visual odometry to measure the ego-motion of a vehicle. The new algorithm introduces an inlier grouping method based on Delaunay triangulation and vanishing point computation. Most visual odometry algorithms rely on RANSAC in choosing inliers. Those algorithms fluctuate largely in processing time between images and have different accuracy depending on the iteration number and the level of outliers. On the other hand, the new approach reduces the fluctuation in the processing time while providing accuracy corresponding to the RANSAC-based approaches.