• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.1
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• pp.9-14
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• 2005

Mode missing of Fabry-Perot laser diodes has been modeled using the time domain laser model(TDLM). Fabry-Perot laser diodes that have structure of ripple in the waveguide of active layer or defects inside the active layer were simulated. For accurate simulation, the nonlinear effects were included such as spatial hole burning(SHB) and gain saturation. From the simulation results, it was founded that the defect inside the active layer in laser diodes has a strong influence on mode missing rather than the waveguide ripple. The simulation results are confirmed with the fabricated Fabry-Perot laser diodes by measuring the longitudinal mode spectra as a function of temperature from $25[^{\circ}C]\;to\;85[^{\circ}C]$.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.1
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• pp.60-65
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• 2010

This paper describes the results of 2D mapping, feature detection and matching to create the surrounding environment in the mounted stereo camera on Mobile robot. Extract method of image's feature in real-time processing for quick operation uses the edge detection and Sum of Absolute Difference(SAD), stereo matching technique can be obtained through the correlation coefficient. To estimate the location of a mobile robot using ZigBee beacon and encoders mounted on the robot is estimated by Kalman filter. In addition, the merged gyro scope to measure compass is possible to generate map during mobile robot is moving. The Simultaneous Localization and Mapping (SLAM) of mobile robot technology with an intelligent robot can be applied efficiently in human life would be based.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.379-381
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• 2013

In this paper, we propose a method to detect the gradient of the spaces between sentences and to deskew in the document image. First, gradient is measured by pixels for spaces between sentences that has been done an edge extraction in document image and then skewed image is corrected by using the value of the gradient which has been measured. Since document image is divided into several areas, it shows a robust processing result by handling the margin, images, and multistage form in the document. Because the proposed method does not use pixel of the character region but use the blank area, degraded document image as well as vivid document image is effectively corrected than conventional method.

• The KIPS Transactions:PartB
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• v.10B no.6
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• pp.705-710
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• 2003

Recent years, as a rapid development of multimedia technology, video database system to retrieve video data efficiently seems to core technology in the oriented society. This thesis describes an efficient automatic frame detection and location method for content based retrieval of video. Frame extraction part is consist of incoming / outgoing car frame extraction and car number frame extraction stage. We gain star/end time of car video also car number frames. Frames are selected at fixed time interval from video and key frames are selected by color scale histogram and edge operation method. Car frame recognized can be searched by content based retrieval method.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.6
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• pp.464-468
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• 2009

In this paper we propose an image-based approach, which is different from the traditional flow cytometric method to detect shape of apoptosis cells. This method can overcome the defects of cytometry and give precise recognition of apoptosis cells. In this work K-means clustering was used to do the rough segmentation and an active contour model, called 'snake' was used to do the precise edge detection. And then some features were extracted including physical feature, shape descriptor and texture features of the apoptosis cells. Finally a Mahalanobis distance classifier classifies the segmentation images as apoptosis and non-apoptosis cell.

• Journal of Broadcast Engineering
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• v.4 no.2
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• pp.119-126
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• 1999

We proposed an algorithm which detects scene changes in video with speediness and accuracy. It is a two-step approach. In the first step, we decide potential scene change segments using the compressed domain data extracted by temporal sampling of MPEG compressed video. In the second step, we determine the exact scene change positions using the pixel values of each frame in those segments by means of combining the intensity and edge changes. In addition we discuss the method to remove false detection generated from camera flash. Integrating the above methods, we introduce a structure that can detect scene changes speedily and accurately.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.541-545
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• 1997

This paper presents a modified geometric active contour model or edge detection and segmentation of computed tomography(CT) scan images. The method is based on the level setup approach developed by Osher and Sethian and the modeling of propagation fronts with curvature dependent speeds by Malladi. Based on above algorithms, the geometric active contour is obtained through a particular level set of hypersurface lowing along its gradient force and curvature force. This technique retains the attractive feature which is topological and geometric flexibility of the contour in recovering objects with complex shapes and unknown topologies. But there are limitations in this algorithm which are being not able to separate the object with weak difference from neighbor object. So we use speed limitation filter to overcome those problems. We apply a 2D model to various synthetic cases and the three cases of real CT scan images in order to segment objects with complicated shapes and topologies. From the results, the presented model confirms that it attracts very naturally and efficiently to the desired feature of CT scan images.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.9
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• pp.76-90
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• 1999

In this paper, a color image retrieval algorithm is proposed based on color histogram and color texture. The representative color vectors of a color image are made from k-means clustering of its color histogram, and color texture is generated by centering around the color of pixels with its color vector. Thus the color texture means texture properties emphasized by its color histogram, and it is analyzed by Gaussian Markov Random Field (GMRF) model. The proposed algorithm can work efficiently because it does not require any low level image processing such as segmentation or edge detection, so it outperforms the traditional algorithms which use color histogram only or texture properties come from image intensity.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.449-450
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• 2007

오래 전 부터 영상처리와 컴퓨터 비전은 많은 분야에 응용되고 발전 되어 왔다. 그러한 기술 중에 최근 각광 받고 있는 그래프 짓(Graph cut) 알고리즘은 에너지함수를 최소화 하는 가장 강력한 최적화 기법중 하나이다. 그리고 일반적으로 Sobel, Prewitt, Roberts, Canny 에지(edge) 검출기 등은 영상처리에서 영상상의 에지를 검출하기 위해 이미 널리 사용되고 발전되어 온 기술이다. 물체에서의 윤곽만 검출하기 위해서는 우리가 원하지 않는 영상 위의 에지도 검출되기 때문에 예지 검출기만으로는 물체의 윤곽만을 검출하는 것은 불가능하다. 우리는 물체의 윤곽만 검출하기를 원하기 때문에 그래프 컷과 에지 검출기의 알고리즘을 결합하면 이러한 문제를 해결 할 수 있다는 것을 제안한다. 이 논문에서는 그래프 컷 알고리즘과 에지 검출기에 관해 간략하게 기술하고 그 결과를 보일 것이다.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.7
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• pp.92-101
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• 1993

This paper describes algorithms to extract license plates in vehicle images. Conventional methods perform preprocessing on the entire vehicle image to produce the edge image and binarize it. Hough transform is applied to the binary image to find horizontal and vertical lines, and the license plate area is extracted using the charateristics of license plates (the boundary information of license plates). Problems with this approach are that real-time processing is not feasible due to long processing time and that the license plate area is not extracted when lighting is irregular such as at night or when the plate boundary does not show up in the image. This research uses the gray level transition characteristics of license plates to verify the digit area by examining the digit width and the gray level difference between the background area the digit area, and then extracts the plate area by testing the distance between the verified digits. This research solves the probelm of failure in extracting the license plates due to degraded plate boundary as in the conventional methods and resolves the provlem of the time requirement by processing in real time such that practical application is possible.