• 한국게임학회 논문지
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• 제20권6호
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• pp.53-62
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• 2020

피사계 심도 효과는 초점이 맞은 부분은 선명하게 나타나고, 그렇지 않은 부분은 흐리게 나타나는 효과를 뜻한다. 본 논문은 실시간 렌더링 환경에서 사용 가능한, 표준 정규 분포를 기반으로 한 샘플링 범위 계산 및 레이어 색상의 알파 블렌딩을 이용한 역방향 매핑 방식 기반의 피사계 심도 효과 구현 방법에 대해 제안한다. 효과 구현을 위해 착란원 크기 계산 방법, 착란원 크기의 표준 정규 분포를 통한 샘플링 영역 설정, 다층 레이어의 알파 블렌딩을 통한 색상 결정 및 디노이징을 통한 이미지 품질 향상 방법에 대해 서술한다.

• Progress in Superconductivity
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• 제8권2호
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• pp.132-137
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• 2007

We have studied superconducting parameters of $MgB_2$ single crystals from reversible magnetization measurements with the magnetic field both parallel and perpendicular to the c-axis of the crystals. The temperature dependence of the London penetration depth, ${\lambda}_{ab}{^{-2}}(T)$, obtained from the Hao-Clem analysis on reversible magnetization, shows a clear discrepancy from single-band theories. It is also found that the anisotropies of the London penetration depth, ${\gamma}_{\lambda}$, slowly increases with temperature while the anisotropy of the upper critical field, ${\gamma}_H$, decreases with temperature. These behaviors are in sharp contrast with the behavior of superconductors with a single band. The temperature dependence of ${\lambda}_{ab}{^{-2}}$, and the opposite temperature dependences of ${\gamma}_{\lambda}\;and\;{\gamma}_H$ can be well explained with the theory of the two-band superconductivity.

• Journal of Radiation Protection and Research
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• 제9권1호
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• pp.19-25
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• 1984

There is not yet an universal method of electron dosimetry. The Authors measured dose distributions of the electron beams from Clinac-18 by means of silicon detector connected to X-Y recorder, and compared them in water phantom with dose distributions measured by film and ion chamber, both inserted in polystyrene phantom. The results are as followings, 1. Dose in build-up region increased with the field size for all energy, and depth dose profiles of $6{\sim}12MeV$ beam under the depth of maximum dose were independent of field size, but those of 15 and 18 MeV beam were dependent on the field size. 2. The widths of penumbra by semiconductor detector were narrower than those by film for same energy beam. 3. Depth dose profiles by three different dosimeter did not coincide each other. In the build-up region, dose by semiconductor detector was lower than that by any other dosimeter.

• 한국농공학회논문집
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• 제51권1호
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• pp.33-39
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• 2009

A number of fallow paddies field continues to increase because of adverse agricultural circumstance such as upsurge income of foreign products, increase of labor costs in local community, imbalance between productivity and profitability etc. Such fallow paddies are necessary to be protected against weeds and trees. If fallow paddies are not managed, it will be devastated and needed cost for re-cultivation. Therefore, management of gradually increased fallow paddy fields should be conducted. In this study, the effect of plants growth inhibition and water quality purification through the control of flood in fallow paddy were examined in an experimental field. The managed and unmanaged fallow paddies through the control of water depth were constructed in the experimental field. The monitoring was conducted from 2005 to 2007. As the result, the managed fallow paddies were more effective than the unmanaged ones on the growth inhibition and water purification. In addition, when the fallow paddy is managed with regular water depth, it was the most effective in the plants growth inhibition.

• Current Optics and Photonics
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• 제2권2호
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• pp.147-152
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• 2018

We propose a novel bi-focal metallic Fresnel zone plate (MFZP) with shallow depth-of-field (DOF) characteristics. We design the specific annular slit patterns, exploiting the phase-selection-rule method along with the particle swarm optimization algorithm, which we have recently proposed. We numerically investigate the novel characteristics of the bi-focal MFZP in comparison with those of another bi-focal MFZP having equivalent functionality but designed by the conventional multi-zone method. We verify that whilst both bi-focal MFZPs can produce dual focal spots at $15{\mu}m$ and $25{\mu}m$ away from the MFZP plane, the former exhibits characteristics superior to those of the latter from the viewpoint of axial resolution, including the axial side lobe suppression and axial DOF shallowness. We expect the proposed bi-focal MFZP can readily be fabricated with electron-beam evaporation and focused-ion-beam processes and further be exploited for various applications, such as laser micro-machining, optical trapping, biochemical sensing, confocal sensing, etc.

• ETRI Journal
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• 제29권3호
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• pp.353-362
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• 2007

In this paper, we propose a novel unsupervised video object extraction algorithm for individual images or image sequences with low depth of field (DOF). Low DOF is a popular photographic technique which enables the representation of the photographer's intention by giving a clear focus only on an object of interest (OOI). We first describe a fast and efficient scheme for extracting OOIs from individual low-DOF images and then extend it to deal with image sequences with low DOF in the next part. The basic algorithm unfolds into three modules. In the first module, a higher-order statistics map, which represents the spatial distribution of the high-frequency components, is obtained from an input low-DOF image. The second module locates the block-based OOI for further processing. Using the block-based OOI, the final OOI is obtained with pixel-level accuracy. We also present an algorithm to extend the extraction scheme to image sequences with low DOF. The proposed system does not require any user assistance to determine the initial OOI. This is possible due to the use of low-DOF images. The experimental results indicate that the proposed algorithm can serve as an effective tool for applications, such as 2D to 3D and photo-realistic video scene generation.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2021년도 제63차 동계학술대회논문집 29권1호
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• pp.257-260
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• 2021

본 논문에서는 카메라의 포커싱과 아웃포커싱에 의해 이미지에서 뿌옇게 표현되는 DoF(Depth of field, 피사계 심도) 영역을 쿼드트리(Quadtree) 기반의 합성곱 신경망을 통해 빠르게 찾는 방법을 제안한다. 우리의 접근 방식은 RGB채널기반의 상호-상관 필터를 이용하여 DoF영역을 이미지로부터 효율적으로 분류하고, 적응형 트리인 쿼드트리를 기반으로 유의미한 영역만을 분류한다. 이 과정에서 손실 없이 온전하게 DoF영역을 추출하기 위한 필터링 과정을 거친다. 이러한 과정에서 얻어진 이미지 패치들은 전체 이미지에 비해 적은 영역으로 나타나며, 이 적은 개수의 패치들을 이용하여 네트워크 단계에서 사용할 이미지-DoF가중치 맵 데이터 쌍을 설정한다. 네트워크 과정에서 학습할 때 사용되는 데이터는 이미지와 상호-상관 필터 기반으로 추출된 DoF 가중치 맵을 이용한다. 본 논문에서 제안하는 쿼드트리 기반 합성곱 신경망은 이미지로부터 포커싱과 아웃포커싱된 DoF영역을 자동으로 추출하는 과정을 학습시키기 위해 사용된다. 결과적으로 학습에 필요한 데이터 영역이 줄어듦으로써 학습 시간과 메모리를 절약했으며, 테스트 결과로 얻은 DoF 가중치 이미지는 입력 이미지에서 DoF영역을 더욱더 빠른 시간 내에 찾아낸다.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2020년도 제62차 하계학술대회논문집 28권2호
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• pp.429-432
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• 2020

본 논문에서는 카메라의 포커싱과 아웃포커싱에 의해 이미지에서 뿌옇게 표현되는 DoF(Depth of field, 피사계 심도) 영역을 합성곱 신경망을 통해 찾는 방법을 제안한다. 우리의 접근 방식은 RGB채널기반의 상호-상관 필터를 이용하여 DoF영역을 이미지로부터 효율적으로 분류하고, 합성곱 신경망 네트워크에 학습하기 위한 데이터를 구축하며, 이렇게 얻어진 데이터를 이용하여 이미지-DoF가중치 맵 데이터 쌍을 설정한다. 학습할 때 사용되는 데이터는 이미지와 상호-상관 필터 기반으로 추출된 DoF 가중치 맵을 이용하며, 네트워크 학습 단계에서 수렴률을 높이기 위해 스무딩을 과정을 한번 더 적용한 결과를 사용한다. 본 논문에서 제안하는 합성곱 신경망은 이미지로부터 포커싱과 아웃포커싱된 DoF영역을 자동으로 추출하는 과정을 학습시키기 위해 사용된다. 테스트 결과로 얻은 DoF 가중치 이미지는 입력 이미지에서 DoF영역을 빠른 시간 내에 찾아내며, 제안하는 방법은 DoF영역을 사용자의 ROI(Region of interest)로 활용하여 NPR렌더링, 객체 검출 등 다양한 곳에 활용이 가능하다.

• Radiation Oncology Journal
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• 제9권2호
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• pp.333-336
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• 1991

충남대학교병원 치료방사선과내 설치되어 있는 6MV선형가속기를 이용하여 음영을 측정하여 다음과 같은 결과를 얻었다. 1) 조사면 크기가 커질수록 음영폭은 중가하였으며 10x10 Cm 이상의 조사면에서는 계산한 음영폭보다 측정치가 대개 크게 나타났다. 조사면이 커질수록 이 차이는 더욱 증가하였다. 2) 깊이가 증가하면 음영폭도 증가하였다. 3) $90\%\~20\%$의 음영폭이 $80\%\~20\%$의 음영폭보다 컸으며 조사면이 커지고, 깊이가 증가할 수록 이 차이는 더 커졌다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회 2차
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• pp.181-185
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• 2010

Until now, design of Earth Retaining is practiced by 2 dimensional analysis for convenience of analysis and time saving. However, the construction field is 3 dimension, in this study, practised the 3 dimensional analysis which can reflect the field condition more exactly the scope of earth retaining wall, and researched about the effective and economical way of design, compared and reviewed with the results, by practising both the 2 and 3 dimensional analysis. existing 2 dimension. the depth of excavation, depth of embedded and soil condition. As result, under the whole conditions, more displacement came to appear to the value as result of 3 dimensional analysis more than the result of 2nd dimensional analysis. Accordingly, the displacement by the 2 dimension analysis is underestimated. Moreover, results of 2 and 3 dimensional analysis, there is no difference at displacement, when the depth of embedded is 0.5H and 1.0H, but Displacement of 1.5H is smaller than 0.5H, 1.0H. That is, the bigger the depth of embedded becomes, the displacement of Earth Retaining Wall appeared smaller. The displacement of earth retaining wall according to depth of excavation appeared bigger, when the depth of excavation is increased. In the meantime, when the soil condition is different, in the 2 dimensional analysis, the displacement appeared biggest, in case of the clay layer, but in the 3 dimensional analysis, in the beginning of excavating, the displacement of earth retaining wall appeared bigger in case of clay layer, but as excavating is in progress, the displacement of both compound soil layer and sand layer appeared big.