• Korean Journal of Optics and Photonics
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• v.21 no.6
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• pp.241-246
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• 2010

In this paper, we propose an electric field enhanced postexposure baking (EFE-PEB) method to obtain deep and high aspect ratio pattern profile in near-field recording. To describe the photoacid distribution under an external electric field during the PEB, we derived the governing equations based on Fick's second law of diffusion. From the results of the numerical calculations, it is found that the vertical movement of photoacid increases while the lateral movement is stationary as electric field varies from 0 to $8.0{\times}10^6\;V/m$. Also, it is proven that the profile of near-field recording is improved by using the EFE-PEB method with increased depth, higher aspect ratio and larger sidewall angle.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.615-616
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• 2008

• The Transactions of the Korea Information Processing Society
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• v.3 no.4
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• pp.926-937
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• 1996

A graph traversal technique is a certain pattern of visiting nodes of a graph. Many special traversal techniques have been applied to solve graph related problems. For example, the depth first search technique has been used for finding strongly onnected components of a directed graph or biconnected components of a general graph. The distributed protocol to implement his depth first search technique on the distributed network can be divided into a fixed topology problem where there is no topological change and a dynamic topology problem which has some topological changes. Therefore, in this paper, we present a more efficient distributed depth first search protocol with fixed topology and a resilient distributed depth first search protocol where there are topological changes for the distributed network. Also, we analysed the message and time complexity of the presented protocols and showed the improved results than the complexities of the other distributed depth first search protocols.

• Journal of the Korean Society of Radiology
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• v.17 no.1
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• pp.31-36
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• 2023

Among imaging and treatment devices for small animals, positron emission tomography(PET) causes a change in spatial resolution within a field of view. This is a phenomenon caused by using a small gantry and a thin and long scintillation pixel, and detectors that measure the interaction depth are being developed and researched to solve this problem. In this study, a detector that measures the interaction depth was designed using several scintillator blocks and light guides with different reflector patterns. The scintillator block composed of 4 × 4 arrays of 3 mm × 3 mm × 5 mm scintillation pixels formed four layers, and a light guide was inserted in each layer to configure the entire detector. In order to check whether the interaction depth was measured, a gamma ray interaction was generated at the center of all scintillation pixels to acquire data and then reconstructed into a flood image. The reflector patterns of the light guides inserted between the layers were all different, so the positions of the scintillation pixels for each layer were formed in different locations. It is considered that even spatial resolution can be achieved over all regions of the field of view if all positions of the scintillation pixels thus formed are separated and used for image reconstruction.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.4
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• pp.322-328
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• 2000

In this paper, we were investigated the detectability on various specimen in self-designed test field using the GPR system with three antenna elements. The GPR system was constantly radiated 730MHz frequency. To examine the detectability on various condition, the test were experimented using different materials, size and buried depth. As an adjusted wave-propagation velocity, the location of hyperbolic curve pattern were displayed B-scan CRT. And the pattern was exactly positioned when it was compared to the real buried-depth. Therefore, we can confirm similarity between the wave-propagation velocity and previous results.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2007.06a
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• pp.90-93
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• 2007

밀도가 높고 주기적으로 배열된 실리콘 나노점이 실리콘 기판위에 형성 되었다. 실리콘 나노점을 형성하기 위해 사용된 나노패턴의 지름은 20 나노미터(nm)이고 깊이는 40 nm 이었으며 기공과 기공사이의 거리는 50 nm 였다. 나노미터 크기의 패턴을 형성시키기 위해서 자기조립물질을 사용했으며 폴리스티렌(PS) 바탕에 벌집형태로 평행하게 배열된 실린더 모양의 폴리메틸메타아크릴레이트(PMMA)의 구조를 형성하였다 폴리메틸메타아크릴레이트를 아세트산으로 제거하여 폴리스티렌만 남아있는 나노크기의 마스크를 만들었다. 형성된 나노패턴에 전자빔 기상증착장치를 사용하여 금 박막을 $100\;{\AA}$ 증착하고 리프트오프(lift-off) 방식으로 금 나노점을 만들었다. 형성된 금 나노점을 불소기반의 화학반응성 식각법을 이용하여 식각하고 황산으로 제거하였다. 형성된 실리콘 나노점의 지름은 24 nm 였고 높이는 20 nm 였다.

• Journal of Digital Contents Society
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• v.6 no.1
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• pp.35-39
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• 2005

It is significantly important problem in computer what is estimating 3D information from 2D images. However, most of the related works have been interested in the analysis of the changes of 2D image, so that, they need much time to solve the complex equation and expensive device. In this paper, we first actively project the pattern of the sinusoidal wave into the object. Then, we measure the change of the phase from the distortion occurring according to the shape of the object, and we use the change of the phase in order to estimate the depth information. This is our proposal.

• Journal of Broadcast Engineering
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• v.21 no.1
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• pp.36-42
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• 2016

Recently, many 3D contents have been produced through the multiview camera system. In this system, since a difference of the viewpoint between color and depth cameras is inevitable, the camera parameter plays the important role to adjust the viewpoint as a preprocessing step. The conventional camera calibration method is inconvenient to users since we need to choose pattern features manually after capturing a planar chessboard with various poses. Therefore, we propose a semi-auto camera calibration method using a circular sampling and an homography estimation. Firstly, The proposed method extracts the candidates of the pattern features from the images by FAST corner detector. Next, we reduce the amount of the candidates by the circular sampling and obtain the complete point cloud by the homography estimation. Lastly, we compute the accurate position having the sub-pixel accuracy of the pattern features by the approximation of the hyper parabola surface. We investigated which factor affects the result of the pattern feature detection at each step. Compared to the conventional method, we found the proposed method released the inconvenience of the manual operation but maintained the accuracy of the camera parameters.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.335-335
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• 2012

높은 효율의 InGaN/GaN 전광소자는 현대 조명 산업에 필수적인 역할을 하고 있다. 전광소자의 효율을 높이는 데에는 여러가지 한계들이 있다. 예를 들면 높은 전류에서의 효율 저하, GaN의 전위결함에 의한 비발광 재결합의 발생 등이 있다. 이러한 한계를 극복하고자 InGaN/GaN 전광소자의 효율을 높이기 위해 사파이어 기판의 표면을 거칠게 바꾸는 방법, 무분극 전광소자, 표면 플라즈몬 등 여러가지 많은 방법들이 개발되고 있다. 본 실험에서는 유기금속화학증착 방법을 이용하여 사파이어 기판위에 Si이 도핑된 n-type GaN를 3.0 um 증착 하였고 그 위에는 9층의 양자 우물 층을 쌓았다. 마지막으로 위층은 Mg 이 도핑된 p-type GaN를 200 nm 증착 하여 소자를 형성하였다. 포토리소그래피 공정과 에칭공정을 통하여 7 um 인 선 패턴을 가진 시료를 완성하였다. 투과 전자 현미경의 측정 결과 맨 위층인 p-GaN의 에칭된 깊이는 175 nm 이였다. 금속박막을 증착하기 위해 열증착 방법으로 금과 은의 박막을 두께를 달리하여 0~40 nm증착 하였다. 금과 은의 두께에 따른 광발광 측정 결과 은(Ag)박막만 40 nm 일 경우 금속박막이 없는 시료보다 광발광 효율이 7배 증가하였고 금 10 nm와 은 30 nm 인 경우에는 3.5배 증가하였다. 또한 패턴의 폭에 따른 광발광 증가를 알아보고 광발광 증가가 일어나기 위한 최적의 패턴조건을 알고자 폭을 5, 10 um 달리하였고, 원자간 힘 현미경과 전자현미경을 이용하여 에칭된 패턴의 폭과 두께를 확인하였다. 본 실험을 통해 금과 은박막에 의한 표면플라즈몬 효과와 광발광 효율증대에 대해 토의할 것이다.

• KIPS Transactions on Software and Data Engineering
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• v.3 no.8
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• pp.309-314
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• 2014

To generate a complete 3D model from depth images of multiple RGB-D cameras, it is necessary to find 3D transformations between RGB-D cameras. This paper proposes a convenient view calibration technique using a spherical object. Conventional view calibration methods use either planar checkerboards or 3D objects with coded-pattern. In these conventional methods, detection and matching of pattern features and codes takes a significant time. In this paper, we propose a convenient view calibration method using both 3D depth and 2D texture images of a spherical object simultaneously. First, while moving the spherical object freely in the modeling space, depth and texture images of the object are acquired from all RGB-D camera simultaneously. Then, the external parameters of each RGB-D camera is calibrated so that the coordinates of the sphere center coincide in the world coordinate system.