• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2015년도 추계학술대회
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• pp.180-181
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• 2015

In this paper, we present a consistent and efficient edit propagation method that is applied for light field data. Unlike conventional sparse edit propagation, the coherency between light field sub-aperture images is fully considered by utilizing light field consistency in the optimization framework. Instead of directly solving the optimization function on all light field sub-aperture images, the proposed optimization framework performs sparse edit propagation in the extended focus image domain. The extended focus image is the representative image that contains implicit depth information and the well-focused region of all sub-aperture images. The edit results in the extended focus image are then propagated back to each light field sub-aperture image. Experimental results on test images captured by a Lytro off-the-shelf light field camera confirm that the proposed method provides robust and consistent results of edited light field sub-aperture images.

• 제어로봇시스템학회논문지
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• 제22권2호
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• pp.139-146
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• 2016

Recently, popularity of 3D technology has been growing significantly and it has many application parts in the various fields of industry. In order to overcome the limitations of 2D machine vision technologies based on 2D image, we need the 3D measurement technologies. There are many 3D measurement methods as such scanning probe microscope, phase shifting interferometry, confocal scanning microscope, white-light scanning interferometry, and so on. In this paper, we have used the extended depth of focus (EDF) algorithm among 3D measurement methods. The EDF algorithm is the method which extracts the 3D information from 2D images acquired by short range depth camera. In this paper, we propose the EDF algorithm using the edge informations of images and the average values of all pixel on z-axis to improve the performance of conventional method. To verify the performance of the proposed method, we use the various synthetic images made by point spread function(PSF) algorithm. We can correctly make a comparison between the performance of proposed method and conventional one because the depth information of these synthetic images was known. Through the experimental results, the PSNR of the proposed algorithm was improved about 1 ~ 30 dB than conventional method.

• Journal of information and communication convergence engineering
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• 제11권2호
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• pp.139-146
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• 2013

This paper proposes a new spatial filtering approach for increasing the depth-of-field (DOF) of imaging systems, which is very useful for obtaining sharp images for a wide range of axial positions of the object. Many different techniques have been reported to increase the depth of field. However the main advantage in our method is its simplicity, since we propose the use of purely absorbing beam-shaping elements, which allows a high focal depth with a minimum modification of the optical architecture. In the filter design, we have used the analogy between the axial behavior of a system with spherical aberration and the transverse impulse response of a 1D defocused system. This allowed us the design of a ring-shaded filter. Finally, experimental verification of the theoretical statements is also provided.

• 방송공학회논문지
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• 제17권4호
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• pp.625-633
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• 2012

카메라로부터 획득한 여러 장의 영상에서 3차원 정보를 얻어내기 위한 Extended Depth of Focus(EDF) 알고리듬은 최근 많은 연구가 이루어지고 있다. 피사물체의 깊이정보에 따른 제한된 초점으로 인해 초점이 일부분 맞는 여러 장의 이미지를 가지고 EDF알고리듬은 각 영상들의 focus 영역에서 하나의 focused 영상과 depth영상을 취득한다. 대부분의 영상처리 알고리듬이 그렇듯, EDF 알고리듬에 사용되는 파라메타들의 초기설정에 따라 결과에 큰 영향을 준다. 본 논문에서는 EDF알고리듬을 적용하기 전 입력영상의 기반으로 pyramid, wavelet transform, complex wavelet transform을 사용하였으며 EDF알고리즘에서 사용되는 파라메타들의 설정에 따른 각 알고리즘의 성능을 분석하였다. 본 논문에서 제시한 파라메타들은 입력영상의 크기에 따른 down sampling의 단계, 영상의 기반 알고리듬의 영상 복원에 사용되는 최하위 레벨의 이미지에 대한 취득 형태, 연산에 쓰이는 window size의 크기이다. 우리는 실험을 통해 제시한 입력영상에 따라 각 파라메타들이 미치는 영향에 대해 분석하였고, 기존에 사용되었던 일반적인 파라메타 선정방식보다 최적화된 파라메타 선정방식을 통해 얻어진 결과영상이 3dB ~ 19dB정도 개선된 것을 확인하였다.

• 한국멀티미디어학회논문지
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• 제18권5호
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• pp.671-681
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• 2015

This paper presents an extended scientific visualization for the public over the scientific visualization targeting for scientists. Our scientific visualization pursues both transmission of scientific information and good-looking visuals. First of all, we examine a tendency to produce scientific images that make the public understand science, even though they are not professional scientists. As a result, we can find several cases that actively generate scientific visualizations for the public. Among them, several research institutes possess own production studio. As the production of scientific images is a convergence field combined of art and science, cooperation between artists and scientists is necessary. Therefore, in-depth communication between them is essential at the planning stage. Moreover, continuous feedbacks between two groups in the production stage, the next stage of the planning, make the scientific visualization to perfection. In this paper, we present 2 modeling methods that are easily encountered during producing scientific visualizations and shading and rendering methods for generating photorealistic images. The concept of an extended scientific visualization that we present shows a new vision of the scientific visualization field.

• 한국지열·수열에너지학회논문집
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• 제4권1호
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• pp.1-10
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• 2008

A magnetotelluric survey and geological survey have been performed to delineate deeply extended fracture systems at the geothermal field in Seokmo Island, Inchon, Korea. One borehole(BH-1) succeed to meet a large fracture system at the depth of 750 m where approximately $72^{\circ}C$ geothermal water is overflowing, while the other borehole(BH-2), which is about 200 m eastward from BH-1, failed to develop enough geothermal water even at the depth of 1,200m. Though there have been so many electric noise sources around the survey region, good quality of MT data above 1 Hz could be obtained with careful installation, remote reference processing. Inversion of MT data for two lines roughly perpendicular to the two major lineaments respectively show that the two lineaments are related to the fracture systems that are extended at least down to 1.5 km depth and inclined eastwards. From the interpretation, additional drilling for BH-2 is recommended and finally meet the fracture systems at the depth of 1,280 m and resulted in overflow of large amount of geothermal water of temperature $69.4^{\circ}C$ from BH-2.

• 방송공학회논문지
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• 제16권5호
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• pp.883-893
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• 2011

본 논문에서는, 피사계심도가 낮은 카메라로 획득한 영상에서 초점이 맞는 부분과 그렇지 않은 부분을 나누는 새로운 초점 정량화를 설계하고 초점 정량화에 기반한 decision map을 이용하여 획득한 영상과 위너필터링으로 복원한 영상의 정합을 통해 영상의 피사계심도를 확장하였다. 기존의 초점 정량화 방법은 고주파 성분의 크기에 따라서 초점 정량화를 수행하므로 초점이 맞지 않은 부분에 고주파 성분이 있는 경우 성능이 저하된다는 단점이 있다. 본 논문에서는 이를 극복하기 위하여 효과적인 대역필터를 설계하였으며 제안하는 방법이 기존에 방법에 비해서 성능이 우수함을 시뮬레이션 및 실험을 통해 입증하였다.

• Journal of the Optical Society of Korea
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• 제19권5호
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• pp.487-493
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• 2015

A wavefront coding (WFC) technique provides an extension of the depth of field for a microscopy imaging system with slight loss of image spatial resolution. Through the analysis of the relationship between the incidence angle of light at the phase mask and the system pupil function, a mixing symmetrical cubic phase mask (CPM) applied to 5X-40X micro-objectives is optimized simultaneously based on point-spread function (PSF) invariance and nonzero mean values of the modulation transfer function (MTF) near the spatial cut-off frequency. Optimization results of the CPM show that the depth of field of these micro-objectives is extended 3-10 times respectively while keeping their resolution. Further imaging simulations also prove its ability in enhancing the defocus imaging.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2010년도 하계학술대회
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• pp.435-437
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• 2010

렌즈의 피사계심도 (Depth of Field)가 낮은 카메라로 영상을 획득 했을 때, 한 영상 내에도 in-focus 영역과 out of-focus 영역이 동시에 존재하게 된다. 따라서 영상을 복원하기 위해 in-focus 영역과 out-of-focus 영역을 구분하는 focus measure가 필요하게 된다. 기존 focus measure 알고리즘은 획득된 영상의 intensity 값의 절대적인 변화나 고주파수 성분 값에 따라 in-focus와 out-of-focus를 결정하기 때문에 out-of-focus 영역이 smooth 하지 않을 경우에는 in-focus 영역이라 잘못 판단할 수 있을 뿐만 아니라 잡음에 민감한 단점을 가진다. 본 논문에서는 기존 알고리즘의 한계점을 보완하는 연구 방향을 제시한다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.1407-1412
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• 2004

Impedance calculations of electric railway traction systems is essential to define characteristics and to design it. The self impedance is defined voltage drop rate per unit length, the mutual impedance is represented as a voltage induced to transmission line from transmission line. The self and the mutual impedance are influenced by ground return currents. The earth is considered as a semi-infinitely extended non-ideal conductor. The current of transmission line produces earth current induced magnetically and it flow through a path having minimum impedance. Carson proposed the impedance calculation formula using wave equations and magnetic field equations. Though the formula have an improper equation, that is still used as a standard impedance calculation method. This paper introduced an impedance calculation method that the complex depth of earth return method assumes that the current in conductor returns through an imagined earth depth path located directly under original conductor at a depth of. In this paper, we showed that this proposed method has a closed form and is easier than Carson's.