• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.88-91
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• 1997

One of the most significant feature of diagnostic ultrasonic instrument is to display information on the soft tissues in the body in real time. In this paper we carried out basic study on the digital moving image processing for tracing the movement of heart valves in echocardiograms. Digital moving image file was made from analog echocardiograms and it was remade as 256 gray-level images on each frame. The ROI(Region of interest) was placed on a heart valve region to process images efficiently. Images were processed by the use of image enhancement filters and morphology filters. The result shows that the processed images were more enhanced than original images. When a moving image is reconstructed by using these enhanced images, we can trace the movement of heart valves more easily. In this study we proposed the availability of the moving image reconstruction using enhancement images.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.303-305
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• 2014

This paper is concerned with the vibration measurement of cable by image processing technique. The measurement system consists of a CCD camera and zoom lens. The image data can be transferred to PC via USB or IEEE1394 port. In this study, a Matlab program was made to process the acquired image data. After acquiring an image data for each frame, this data is binarized for tracing cable vibrations. Then the area occupied by the cable is marked by 1 and the background is covered by 0. In this way, we can calculate the displacement of the cable. Experimental results show that the tracing of cable displacements is possible and natural frequencies and mode shapes can be computed. The accuracy of the image processing system for vibration measurement depends on the maximum frame rate of the CCD camera. The use of a high-speed camera enables us to compute more higher modes. The laboratory experiments guarantee the vibration measurement of real transmission lines.

• 대한의용생체공학회:의공학회지
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• 제28권4호
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• pp.520-529
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• 2007

An efficient method for implementing image reconstruction algorithms for Compton cameras is presented. Since Compton scattering formula establishes a cone surface from which the incident photon must have originated, it is crucial to implement a computationally efficient cone-surface integration method for image reconstruction. In this paper we assume that a cone is made up of a series of ellipses (or circles) stacked up one on top of the other. In order to reduce computational burden for tracing ellipses formed by the intersection of a cone and an image plane, we propose a new method using a series of imaginary planes perpendicular to the cone axis so that each plane contains a circle, not an ellipse. In this case the cone surface integral can be performed by simply accumulating the circles along the cone axis. To reduce the computational cost of tracing circles, only one of the circles in the cone is traced and the rest are determined by using simple trigonometric ratios. For our experiments, we used the three different schemes for tracing ellipses; (i) using the samples generated by the ellipse equation, (ii) using the fixed number of samples along a circle on the imaginary plane, and (iii) using the fixed sampling interval along a circle on the imaginary plane. We then compared performance of the above three methods by applying them to the two reconstruction algorithms - the simple back-projection method and the expectation-maximization algorithm. The experimental results demonstrate that our proposed methods (ii) and (iii) using imaginary planes significantly improve reconstruction accuracy as well as computational efficiency.

• 한국정밀공학회지
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• 제33권6호
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• pp.491-497
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• 2016

This study aims to develop a vision inspection system for screw threads. To inspect external defects in screw threads, the vision inspection system was developed using front light illumination from which bright images can be obtained. The front light system, however, requires multiple side images for inspection of the entire thread surface, which can be performed by omnidirectional optics. In this study, an omnidirectional optical system was designed to obtain annular images of screw threads using an image sensor and two reflection mirrors; one large concave mirror and one small convex mirror. Optical simulations using backward and forward ray tracing were performed to determine the dimensional parameters of the proposed optical system, so that an annular image of the screw threads could be obtained with high quality and resolution. Microscale surface defects on the screw threads could be successfully detected using the developed annular inspection system.

• 한국정밀공학회지
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• 제28권9호
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• pp.1094-1102
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• 2011

Recent trends for the miniaturization and weight reduction of portable electronic parts is the use of subminiature components. Assembly of the miniaturized components requires subminiature screws of which pitch sizes are in a micrometer scale. To produce such a subminiature screw with high precision threads, not only a precision forming technology but also high-precision measurement technique is required. In the present work, a vision inspection system is developed to measure the thread profile of a subminiature screw. Optical simulation based on a ray tracing method is used to design and analyze the optical system of the vision inspection apparatus. Through this simulation, optical performance of the developed vision inspection system is optimized. The image processing algorithm for the precision screw inspection is also discussed.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.169-172
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• 1998

A 3D-ray tracing using triangular ray tubes for predicting propagation in indoor environments is presented. Employed ray tracing scheme needs no reception sphere often suffered from how to assign the correct radius as a touching ray on the receiver. To verify the developed codes path loss for a rectangular corridor has been computed, measured, and compared with those by image methods, all shows good agreement to each other. Discussions are made on the path loss fluctuations along the distance in a rectangular corridor having a conducting knife.

• 자연과학논문집
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• 제16권1호
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• pp.31-37
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• 2005

6면 프리즘 렌즈가 장착된 렌즈메터에서 상점의 위치로부터 시험렌즈의 편심의 위치를 알아 낼 수 있는 알고리즘을 개발하였다. 6개의 프리즘에 의해 형성되는 6개의 상점은 시험렌즈의 편심의 극좌표에 의해 변하게 되며, 비틀린 광선 추적으로 계산할 수 있다. 광학 설계 프로그램인 Code V를 사용하여 렌즈메터 광학계를 분석하고, 시험렌즈의 위치에 따른 상점의 위치 변화를 함수로 나타내서 역으로 상점의 위치로부터 시험렌즈의 편심의 위치를 알아낼 수 있는 방법을 개발하였다.

• 한국광학회:학술대회논문집
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• 한국광학회 2008년도 하계학술발표회 논문집
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• pp.403-404
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• 2008

This report described the development of Vision Inspector program which can simulate numerically the image acquisition process of Machine Vision System for automatic optical inspection of any products. The program consists of an illuminator, a product to be inspected, and a camera with image sensor, and the final image obtained by ray tracing.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.379-382
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• 2005

This study proposes an effective algorithm that can render a realistic image of a lighting environment, especially an automotive rear lamp, using the backward ray tracing method. To producea realistic image similar to that perceived by the human eye, the incident light energy at the eye point estimated by a ray tracing algorithm is represented by XYZ tri-stimulus values, which are then converted into RGB values considering the particular display device.

• 인지과학
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• 제2권2호
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• pp.341-358
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• 1990

본 논문은 기존의 세선화 알고리즘이 갖는 문제점의 하나인 잡음을 해결하는 방법을 제안하였다. 이를 위하여 세선화 알고리즘은 Pavlidis에 의해 제안된 방식을 근간으로 하였으며,외곽추적을 수행할때 제안된 $3{\times}3$ 마스크로부터 잡음을 판별해 낼 수 있도록 하였다. 그리고, 추적이 완료되면 자동적으로 잡음이 제거되도록 하였다. 이 방법을 구현시켜 얻어진 세선화 결과는 잡음이 없는 경우와 유사한 형태를 보이고 있으며, 잡음이 있는 경우에 비해 간략화된 구조르 갖음을 알수가 있다. 이와같은 결과는 인식단계의 구성요소들이 간략화 될수 있는 근거를 제공하여 주게 된다.