• Smart Structures and Systems
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• 제24권5호
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• pp.659-668
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• 2019

In digital image correlation, speckle image is closely related to the measurement accuracy. A practical global evaluation criterion for speckle image is presented. Firstly, based on the essential factors of the texture image, both the average particle size and image sharpness are used for the assessment of speckle image. The former is calculated by a simplified auto-covariance function and Gaussian fitting, and the latter by focusing function. Secondly, the computation of the average particle size and image sharpness is verified by numerical simulation. The influence of these two evaluation parameters on mean deviation and standard deviation is discussed. Then, a physical model from speckle projection to image acquisition is established. The two evaluation parameters can be mapped to the physical devices, which demonstrate that the proposed evaluation method is reasonable. Finally, the engineering application of the evaluation method is pointed out.

• 대한전자공학회논문지SP
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• 제46권1호
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• pp.7-13
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• 2009

본 논문은 디지털 자동초점을 위한 등방성 점확산함수 추정에 관한 새로운 방법을 제안한다. 제안하는 알고리듬은 영상의 윤곽에서 방향을 판단하고 방향에 따라 윤곽 프로파일을 수집한다. 수집한 윤곽 프로파일을 평균하여 계단응답을 만들고 등방성 점확산함수의 특징을 이용하여 점확산함수를 추정한다. 실험을 통해 열화된 영상에서 제안하는 알고리듬으로 점확산함수를 추정하는 과정을 보이고 정확성을 증명한다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
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• pp.401-404
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• 2004

SAR (Synthetic Aperture Radar) signal data need a focusing procedure to make the information available to the user. In recent SAR systems, various sensing modes and mission operations are applied to acquire high-resolution SAR images. Therefore, in order to develop generalized focusing software for multi-satellites, a regularized parameter configuration that sufficiently represents sensor and platform characteristics of the SAR system is required. The objective of this paper is to introduce the consideration of parameter definition for developing a generalized SAR processor and to discuss the flexibility and extensibility of defined parameters. The proposed parameter configuration can be applied to a SAR processor. Experiments based on real data will show the suitability of the suggested processing parameters.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.825-826
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• 2008

Focusing is the principal factor that decides the image quality. In the low illuminance condition, captured images with a digital camera usually blurred because the autofocus system of the camera fail to detect the in-focus position. The failure of focusing is due to thermal noise in the captured image. In this paper, we propose a new focus detection algorithm. The proposed algorithm use the new focusing index which is weighted sum of the high-frequency energy and mid-frequency energy. The weight is determined by the local variance of the image. The proposed algorithm performs stable focusing detection with in the low illuminance condition.

• 대한전기학회논문지:시스템및제어부문D
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• 제55권7호
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• pp.313-318
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• 2006

An automatic sample centering system is underway at the protein crystallography beam line of the Pohang Light Source to improve the efficiency of the crystal screening process. A sample pin which contains a protein crystal is mounted on a goniometer head. Then the crystal should be moved to the center of X-ray beam by controlling the motorized goniometer to obtain diffraction data. Since the X-ray beam is located at the center of the image obtained from the CCD camera when the image of the sample pin is in focus, an auto-focusing algorithm is a very important part in the auto-sample-centering system. However the results of applying several well-known auto focusing algorithms directly to the images are not satisfactory owing to the following factors: misalignment of CCD camera, non-uniform cryo-stream in the background of the image and the supporter of the loop. The performance of an auto-focusing algorithm can be increased if the algorithm is applied to only the loop region identified. Non-uniform cryo-stream and a various illumination condition and a stain, which is shown in the image, are main obstacles to loop region identification. In this paper, a simple loop region identification algorithm, which can solve these problems, is proposed and the effective ness of the proposed scheme is shown by applying the auto-focusing algorithm to the loop region identified.

• 대한전자공학회논문지SP
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• 제47권5호
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• pp.145-152
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• 2010

본 논문에서는 초점 열화를 제거하기 위해서 반복적 Unsharp mask (UM) 필터를 이용한 디지털 자동초점 기법을 제안한다. 제안한 디지털 자동초점 기술은 영상열화를 추정하기 위해서 점확산함수를 추정하지 않고 단순한 필터를 사용하기 때문에 계산량이 적은 장점을 갖는다. 본 기법은 반복적 필터 구조로 영상을 복원하기 때문에 사용자의 주관적 기준 및 영상의 객관적 지표를 사용하여 필터링의 반복 회수를 제한할 수 있다. 또한 반복적 UM 기반의 영상개선 방법이 기존의 반복적 영상복원 기술과 등가임을 보인다. 마지막으로 본 논문에서 제안한 알고리듬의 성능평가를 위해서 기존의 영상복원 기반의 디지털 자동초점 기술과의 비교 실험을 수행하였고, 이를 통하여 제안한 디지털 자동초점 기법이 주관적으로나 객관적으로 우수함을 보였다.

• 한국조경학회지
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• 제32권1호
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• pp.47-56
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• 2004

Rapid economic development in Korea caused functions of city functions such as concentration of population, deterioration of the quality of living environment and traffic congestion. Korean cities have lost their identity becausr they are merged functionally and physically with neighboring cities, forming one mesa-city. Unified shape and disorganized streets of cities often cause confusion among foreigners and visitors. It is very difficult for them to find their image in strange cities. It is, however, important to correctly analyze the image and meaning of cities for understanding its identity. The purpose of this study is to develop a method to analyze the city image by focusing on some of the main cities in Korea. For this purpose, the adjective questionnaire and multi-dimension scaling (MDS) are applied to the analysis of city image. Image analysis graph by MDS can visually present the general and integrate images. The results of this study are summarized as follows: The important factors for interpretation of city image are historical and industrial character. Seoul, Taegu and Pusan have industrial and complex city images. Kongju has historical city image, while Changwon has a modern image. Chuncheon belongs to a soft and small image. Each city has an alternative solution against a negative image, according to the image analysis graph.

• 한국안광학회지
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• 제8권2호
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• pp.177-183
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• 2003

한의학, 진단학에서 사용되는 홍채 촬영용 광학계를 설계 제작해 보았다. 전체 구성은 광원부, 결상광학계, 촬상구동부, 진단 S/W로 되어있다. 결상광학계는 FD60, BACD5의 재질로 색수차를 제거한 0.58X배의 축소광학계로 설계하였다. 결상광학계의 국산화는 제품 전체의 원가절감에 큰 기여를 하게 되었다. 제작되어진 촬영장치는 외국제품과 비교해 볼 때 영상의 입체감에서 우수한 성능을 가직 가지게 되었다.

• 디지털산업정보학회논문지
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• 제5권3호
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• pp.135-140
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• 2009

In this paper, a robot control system with stereoscopic Image was presented. The robot control system has an auto-focusing functionality which measures the distance between robot and object using an infrared sensor. By providing depth and information based on the stereoscopic image, it allows user to have presence and immersion as if he(she) be there. the proposed robot control system's propriety was examined through the comparison experiment with the mono-scopic image.

• Journal of electromagnetic engineering and science
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• 제12권1호
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• pp.26-31
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• 2012

We have proposed a metamaterial lens that enables sub-wavelength focusing, which is shorter than an operating wavelength. Our lens is a two dimensional array of a unit cell consisting of a metallic dual-plate printed on a dielectric substrate. The unique dual-plate structure provides negativeness both in permittivity and permeability, with no help from conventional additional structures, which are normally printed on the opposite of metallic patterns. Therefore, we can focus a source (or an image) in a tiny distance shorter than the free space wavelength (${\lambda}$) at the frequencies of interest. Furthermore, since the proposed geometry does not need separate supplementary structures to acquire negative permittivity or permeability, our lens is much simpler than conventional metamaterial lenses, which is a strong point in practical applications. We have validated sub-wavelength focusing ability in a 6 GHz frequency band through an experiment of near field scanning, which provided the width of about 0.19 ${\lambda}$ at a half maximum of a peak value of an measured image. The width of the focused image through the lens is more than 4 times shorter than that without the lens, which confirms the validity of our design approach.