• Nuclear Engineering and Technology
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• 제52권6호
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• pp.1271-1276
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• 2020

The geometrical efficiency of a source-to-detector configuration is considered to be necessary in the calculation of the full energy peak efficiency, especially for NaI(Tl) and HPGe gamma-ray spectroscopy detectors. The geometrical efficiency depends on the solid angle subtended by the radioactive sources and the detector surfaces. The present work is basically concerned to establish a new mathematical approach for calculating the solid angle and geometrical efficiency, based on conversion of the geometrical solid angle of a non-axial radioactive point source with respect to a circular surface of the detector to a new equivalent geometry. The equivalent geometry consists of an axial radioactive point source with respect to an arbitrary elliptical surface that lies between the radioactive point source and the circular surface of the detector. This expression was extended to include coaxial radioactive circular disk source. The results were compared with a number of published data to explain how significant this work is in the efficiency calibration procedure for the γ-ray detection systems, especially in case of using isotropic radiating γ-ray sources in the form of point and disk shapes.

• 한국산학기술학회논문지
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• 제10권1호
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• pp.117-121
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• 2009

어안 렌즈 카메라로 촬영한 어안 영상은 일반 카메라 영상보다 화각이 크다. 반면 영상에서 피사체의 왜곡이 커서 사용자의 인지가 어려우므로 원근 영상으로 변환이 필요하다. 기존의 Ishii 방법[1]은 등거리 투영을 사용하므로 피사체가 변환 영상에서 크기와 기하학적 왜곡이 생기는 문제점을 가지고 있었다. 본 논문에서는 스케일링 함수를 이용한 어안 영상의 원근 영상 변환 방법을 제안하였다. 실험에서, 제안한 방법은 스케일링 함수를 적용함으로써 크기 왜곡과 기하학적 왜곡이 감소되었다.

• East Asian mathematical journal
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• 제31권2호
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• pp.167-188
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• 2015

Formula for the area of a trapezoid is an educational material that can handle algebraic and geometric perspectives simultaneously. In this note, we will make up the expression equivalent algebraically to the formula for the area of a trapezoid, and deal with the conversion of a geometric point of view, in algebraic terms of translating and interpreting the expression geometrically. As a result, the geometric conversion model, the first algebraic model, the second algebraic model are obtained. Therefore, this problem is a good material to understand the advantages and disadvantages of the algebraic and geometric perspectives and to improve the mathematical insight through complementary activity. In addition, these activities can be used as material for enrichment and gifted education, because it helps cultivate a rich perspective on diverse and creative thinking and mathematical concepts.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.67-70
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• 2009

This paper proposes an algorithm for creating stereoscopic video from a monoscopic video. A viewer uses depth perception clues called a vanishing point which is the farthest from a viewer's viewpoint in order to perceive depth information from objects and surroundings thereof to the viewer. The viewer estimates the vanishing point with geometrical features in monoscopic images, and can perceive the depth information with the relationship between the position of the vanishing point and the viewer's viewpoint. In this paper, we propose a method to estimate a vanishing point with edge direction histogram in a general monoscopic image and to create a depth map depending on the position of the vanishing point. With the conversion method proposed through the experiment results, it is seen that stable stereoscopic conversion of a given monoscopic video is achieved.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 춘계학술대회 논문집
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• pp.172-176
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• 1995

Schemes to trap weakly absorbed light into the cell have played an important role in improving the efficiency of both amorphous and crystlline silicon solar cells. One class of scheme relies on randomizing the direction of light within the cell by use of Lambertian(diffuse)surfaces. A second class of scheme relies on the use fo well defined geometrical features to control the direction of light wihin the cell, Widly used geometrical features in crystalline silicon solar cells are the square based pyramids and V-shaped grooves formed in (100) orientated surfaces by intersecting(III) crystallographic planes exposed by anisotropic etching. 18.5% conversion efficiency of Buried Contact Solar Cell with pyramidally textured surface has been achieved. 18.5% efficiency of silicon solar cell is one the highest record in the world The efficieny of cell without textured surface was 16.6%, When adapting textured surface to the Cell, the efficiency has been improved over 12%.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
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• pp.415-429
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• 2002

Various modeling techniques for ultrasonic wave propagation and scattering problems in finite solid media are presented. Elastodynamic boundary value problems in inhomogeneous multi-layered plate-like structures are set up for modal analysis of guided wave propagation and numerically solved to obtain dispersion curves which show propagation characteristics of guided waves. As a powerful modeling tool to overcome such numerical difficulties in wave scattering problems as the geometrical complexity and mode conversion, the Boundary Element Method(BEM) is introduced and is combined with the normal mode expansion technique to develop the hybrid BEM, an efficient technique for modeling multi-mode conversion of guided wave scattering problems.

• 대한전자공학회논문지
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• 제25권9호
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• pp.1125-1133
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• 1988

This paper described construction of CIF and DXF parser using YACC (yet another compiler compiler), in order to plot CIF, and conversion of DXF into CIF for geometrical information of AUTOCAD. It is difficult to construct parper for input with complex grammar or with grammar which has possibilities of extension, and to varify the validity. YACC, a LALR parser generator, is a effective tool in these works. Also DRC or ERC can be developed quickly using primitive CIF in this paper. So, it is practicable to design IC at PC without expensive workstations.

• 한국정보통신학회논문지
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• 제19권7호
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• pp.1646-1652
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• 2015

본 논문에서는 집적영상에서 정치실영상을 재생하기 위한 깊이변환법을 제안한다. 종래의 집적영상은 재생상이 반전된 깊이로 재생되는 도치영상 문제가 있다. 재생상의 깊이는 개별 요소영상의 좌표에 의해 결정된다. 요소영상 획득과 재생시스템의 기하학적 관계를 분석하여 재생상의 깊이 변환 에 필요한 수식 유도가 가능하며 이를 이용하여 도치영상을 정치영상으로 변환할 수 있다. 제안하는 방법의 유용성을 보이고 또한 이론적 분석을 검증하기 위하여 실험을 수행하였고 그 결과를 제시한다.

• 한국통신학회논문지
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• 제34권8C호
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• pp.782-789
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• 2009

본 논문에서는 2차원 단안 동영상으로부터 3차원 입체 동영상을 생성하는 기법을 제안한다. 3차원 공간에서 평행한 직선은 2차원 평면의 투시영상에서 먼 거리일수록 간격이 좁아져서 마지막에 한 점에서 만나게 되며, 이 점을 소실점(vanishing point)이라고 정의한다. 관찰자는 관찰자의 시점으로부터 가장 먼 지점인 소실점이라는 깊이 지도 지각 단서를 활용하여 객체와 배경으로부터 관찰자까지의 깊이 정보를 인지한다. 일반적으로 2차원 단안 영상에서의 기하학적 특성을 이용해서 소실점을 추정하고, 소실점의 위치와 관찰자의 시점과의 관계를 이용하여 깊이 정보를 인지할 수 있다. 본 논문에서는 일반적인 2차원 단안 영상에서 에지 방향성 히스토그램을 이용하여 소실점의 위치를 추정하고, 소실점의 위치에 따른 깊이지도(depth map)를 생성하는 방법은 제안한다. 실험 결과를 통해서 생성된 깊이지도를 이용하여 안정된 3차원 입체 동영상을 만들 수 있다.

• 센서학회지
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• 제32권2호
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• pp.110-117
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• 2023

Reconstructing underwater geometry in real time with forward-looking sonar is critical for applications such as localization, mapping, and path planning. Geometrical data must be repeatedly calculated and overwritten in real time because the reliability of the acoustic data is affected by various factors. Moreover, scattering of signal data during the coordinate conversion process may lead to geometrical errors, which lowers the accuracy of the information obtained by the sensor system. In this study, we propose a three-step data processing method with low computational cost for real-time operation. First, the number of data points to be interpolated is determined with respect to the distance between each point and the size of the data grid in a Cartesian coordinate system. Then, the data are processed with a nonlinear interpolation so that they exhibit linear properties in the coordinate system. Finally, the data are transformed based on variations in the position and orientation of the sonar over time. The results of an evaluation of our proposed approach in a simulation show that the nonlinear interpolation operation constructed a continuous underwater geometry dataset with low geometrical error.