• Journal of KIISE:Software and Applications
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• v.35 no.3
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• pp.162-168
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• 2008

A look-up table based vector adaptive filter is proposed in color inverse halftoning. Inverse halftoning converts halftone image into a continuous-tone image. The templates and training images are required in the process of look-up table based methods, which can be obtained from distributed patterns in the sample halftone images and their original images. Although the look-up table based methods usually are faster and show better performances in PSNR than other methods do, they show wide range of qualities depending on how they treat nonexisting patterns in the look-up table. In this paper, a vector adaptive filter is proposed to compensate for these nonexisting patterns, which achieves better quality owing to the contributed informations about hue, saturation, and intensity of surrounding pixels. The experimental results showed that the proposed method resulted in higher PSNR than that of conventional Best Linear Estimation method. The bigger the size of the template in the look-up table becomes, the more outstanding quality in the proposed method can be obtained.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1010-1011
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• 2015

최근 고효율 전력변환을 위해 LLC 공진형 하프브릿지 컨버터의 동기정류기에 대한 연구가 활발히 진행되고 있다. 기존 일반적인 다이오드 정류기를 사용하는 경우 출력전류에 비례하는 전력손실이 커서 대전력용으로 사용하기에는 적합하지 않다. 따라서 스위치를 이용한 동기정류기가 검토되고 있는데 동기정류기의 스위치를 구동시키기 위해서는 스위치를 구동시킬 수 있는 구동용 IC가 이용되고 있다. 동기정류기 구동 IC의 단점으로는 약 50%의 중부하 이하에서는 동작되지 않는 단점이 있어 이를 보완하기 위하여 변압기 1차측 전류를 검출하여 게이트 전압을 만들어 스위치를 구동시키는 회로를 제안하였다. 본 논문의 실험 결과 저전력 지점에서 동기정류기가 구동되었고 따라서 전력변환 효율은 기존의 다이오드 정류기에 비해 우수하며 효율개선효과가 있다는 것을 실험으로 보였다.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.5
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• pp.637-642
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• 2011

In this paper, a new technique to estimate the distances between a vanishing point and moving objects is proposed. A vanishing point for an input image is estimated and it use to extract distance form the vanishing point to a moving object. Using the obtained distances, moving objects is extracted. In simulation results, several performances for a test image sequnce is shown.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.156-158
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• 2019

낮은 저항 용기를 가열할 수 있는 유도 가열 장치는 유도가열 장치용 하프 브릿지 직렬 공진형 인버터의 높은 입력 전압과 높은 턴 수의 코일을 통해 낮은 저항의 용기를 가열한다. 그러나 자성체 용기는 높은 턴 수의 코일에서 높은 저항 값을 가지므로 적절한 전력을 내기 위해서는 높은 입력 전압이 필요하다. 이러한 경우 부스트 토폴로지의 역률 개선 회로를 사용할 수 있다. 하지만 입력 전압의 변동에 따라 직렬 공진형 인버터의 출력 전력 제어를 위한 동작 점 변동이 필요하므로 인버터의 손실이 변동한다. 본 논문에서는 낮은 저항 용기를 가열하기 위하여 높은 턴 수의 코일을 탑재한 유도 가열 장치용 하프 브릿지 직렬 공진형 인버터에서 자성체 용기의 가열 시 입력 전압 변동에 따른 인버터의 손실 분석을 통해 최적의 입력전압 조건을 선정하고자 한다. 제안하는 입력전압 선정 기법은 2-kW 급 유도 장치용 하프 브릿지 직렬 공진형 인버터 시 제품을 통해 타당성을 검증한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1C
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• pp.72-80
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• 2009

Look-up table based inverse halftoning from the digital color halftone image is proposed in this paper, which uses vector adaptive filter for the nonexisting patterns in the table. Halftone image is obtained from a continuous -tone image, which can be restored into continuous one from the digital binary image by way of inverse halftoning method. Look-up table based method usually processes fast and has even performances over the various halftoning. The numbers of pixels in the pattern of table and the method how to define the table elements for each R, G, B channels can effect largely for its performance. The proposed method uses 16 pixels in the table considering the diversity of the expressions from their patterns and with memory size as well. This also proposed how to combine R, G, B channels into one. Experimental results showed the better performance in the expression of colors, better color restoration and the short processing time compared with the conventional ones.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.5
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• pp.175-182
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• 2010

The paper presents a novel algorithm for face and iris detection with the application for driver iris monitoring. The proposed algorithm consists of the following major steps: Skin-color segmentation, facial features segmentation, and iris positioning. For the skin-segmentation we applied a multi-layer perceptron to approximate the statistical probability of certain skin-colors, and filter out those with low probabilities. The next step segments the face region into the following categories: eye, mouth, eye brow, and remaining facial regions. For this purpose we propose a novel segmentation technique based on estimation of facial class probability density functions (PDF). Each facial class PDF is estimated on the basis of salient features extracted from a corresponding facial image region. Then pixels are classified according to the highest probability selected from four estimated PDFs. The final step applies the circular Hough transform to the detected eye regions to extract the position and radius of the iris. We tested our system on two data sets. The first one is obtained from the Web and contains faces under different illuminations. The second dataset was collected by us. It contains images obtained from video sequences recorded by a CCD camera while a driver was driving a car. The experimental results are presented, showing high detection rates.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.2
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• pp.105-113
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• 2011

In this paper, photovoltaic module integrated converter (MIC) based on active clamp current-fed half-bridge converter is proposed. The converter stage operates in zero-voltage condition using active clamp technique. The theoretical study and circuit design for proposed inverter are confirmed with PSIM simulator and experimental reusult.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.3
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• pp.48-57
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• 2005

This paper presents a novel algorithm in order to extract lane-related information based on machine vision techniques. The algorithm makes up for the weak points of the former method, the Edge Distribution Function(EDF)-based approach, by introducing a Lane Boundary Pixel Extractor (LBPE) and the well-known Hough Transform(HT). The LBPE that serves as a filter to extract pixels expected to be on lane boundaries enhances the robustness of machine vision, and provides its results to the HT implementation and EDF construction. The HT forms the accumulator arrays and extracts the lane-related parameters composed of orientation and distance. Furthermore, as the histogram of edge magnitude with respect to edge orientation angle, the EDF has peaks at the orientations corresponding to lane slopes on the perspective image domain. Therefore, by fusing the results from the EDF and the HT the proposed algorithm improves the confidence of the extracted lane-related information. The system shows successful results under various degrees of illumination.

• The Magazine of the IEIE
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• v.15 no.1
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• pp.106-113
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• 1988

현재 필자가 소속하고 있는 연구실에서는, 컴퓨터 아니메이숀, 컴퓨터 그래픽, 화상처리, 인공지능에 관한 연구등을 하고 있다. 본고에서는 화상처리에 관한 연구중에서, 본 연구실에서 최근에 발표한 컴퓨터 비죤에 관계있는 각종의 도로 정보처리에 관한 연구에 대해서 소개한다. 우선, 화상처리의 수법을 이용한 자동조종의 연구로서, 고속도로에서의 선행차의 자동동정에 관한 연구와 하프변환을 이용한 차량번호판 추출에 관한 연구에 대해서 소개한다. 다음에 도로망 지도처리에 관한 연구로서, 차재형 자동항법 시스템의 개요에 관한 소개와 최단시간 경로에 관한 연구, 도로지도의 자동판독에 관한 연구에 대해서 소개한다. 가까운 미래에, 점점 자동차의 자동화가 추진되고, 인공위성을 이용해서 자동차의 현재 위치를 정확하게 파악할 수 있게 되면, 본고에서 소개하는 연구들이 보다 중요한 의미를 가지게 되리라 생각한다.

• Journal of Korea Multimedia Society
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• v.19 no.10
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• pp.1747-1758
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• 2016

In this paper, we propose a new fast Hough transform to improve the processing time and line detection of Hough transform that is widely used in various vision systems. First, for the fast processing time, we reduce the number of features by using multi-statistical methods and also reduce the dimension of angle through six separate directions. Next, for improving the line detection, we effectively detect the lines of various directions by designing the line detection method which detects line in proportion to the number of features in six separate directions. The proposed method was evaluated with previous methods and obtained the excellent results. The processing time was improved in about 20% to 50% and line detection was performed better in various directions than conventional methods with experimental images.