• 한국태양에너지학회 논문집
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• 제31권3호
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• pp.36-41
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• 2011

Nowadays, the solar expose right is very important with people's life. Therefore, in calculating the sunshine hours, the point analysis and area analysis methods are used in previous studies. Previous two methods have merits and faults. Therefore, ray-tracing method is used as a alternative. Ray-tracing method is adopted by the software of Autodesk Ecotect which is a widely used program by the architectural company and academic university. In this study first, ray-tracing methodology is studied with how to calculate the overshadowing area and, secondly, the sensitivity of the two major factors, overshadowing accuracy and sky subdivision, is analyzed. With these results, appropriate application of the ray-tracing method is presented.

• 한국통신학회논문지
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• 제21권7호
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• pp.1668-1676
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• 1996

This paper presents the evaluation of an angular spectrum-based method used to calculate scattering pattern of a three-dimensional object modelled as a collection composed of vertical sectional two-dimensional images. This is done via comparing a proposed method with two existing methods, i.e., a Fresnel hologram method and a ray-tracing method, in terms of computatioal complexities and reconstructed results. Maathematical derivations for each methods are reviewed and implementing procedures are described in detail, along with the amount of computaions required from the implementation point of view, rather than from the mathematical point of view. We show simulation results in which the Fresnel holoram method dose not exhibit promising results although it requires the least computation. Moreover, it is also shown that the proposed method, even with much less computational requirement than the ray-tracing method, produces good performances asmuch as the ray-tracing method does.

• 한국지진공학회논문집
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• 제5권5호
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• pp.57-61
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• 2001

이 논문은 지진요소 결정의 정확성과 안정성을 향상시키기 위하여 파형분석과 두 점을 잇는 파선추적을 이용한 지진요소 결정 알고리즘을 소개한다. 지진의 규모가 상대적으로 작을 때(일반적으로 $m_{b}$<3.2)Pn이 관찰되지 않고 PmP가 초동파로 기록된 것처럼 보인다. 이러한 경우, P파의 초동파와 S파를 이용하여 기존의 방법으로 계산된 지진요소들과 PmP와 SmS를 이용하여 이 연구에서 개발된 방법으로 계산된 지진요소들은 큰 차이를 보인다. 실제 지진에 대한 지진요소 결정의 계산결과는 이 방법이 기존의 방법보다 rms 오차가 크게 줄었음을 보여준다.다.

• 대한전자공학회논문지
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• 제26권8호
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• pp.1270-1281
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• 1989

This paper presents two new storage schemes of 3-D objects to accelerate the finding of the first intersecting object and the shadow computation steps in ray tracing. The 3-D objects which are potentially intersected with the first reflection (refraction)ray are enrolled within a so called reflection (refraction) frustum' for a polygon object. Only those objects registered in the corres ponding frustum are immediately checked for intersection with the secondary rays emanating from the same polygon. The other is called a shadow pyramid' which contains the candidate objects possibly blocking the path from the relevant light source to any point on the relevant polgon. The shadow testing of a point is performed only against the objects contained in the associated shadow pyramid. Despite the cost needed for registration of objects within frusta or shadow pyramids, the total rendering time of ray tracing using the proposed approaches was reduced by approximately 50% (10% in color rendering time and 70% in shadoe testing time) from the conventional cell 50% (10% in color rendering time and 70% in shadow testing time) from the conventional cell traversal scheme under the 3-D uniform subdivision environment due to the fast finding of candidate objects for intersection and the reduced number of intersection calculations.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.57-65
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• 2000

파형분석과 두 점을 잇는 파선추적은 진원요소 결정의 정확성을 향상시키는 주요한 요인이다. 본 연구에서는 3성분 지진기록의 직선형도(rectilinearity) 함수와 방향성(directionality)함수를 사용하여 파형분석한 결과와 두 점을 잇는 파선추적을 기존의 진원요소결정 프로그램에 적용하여 진원요소 결정의 정확성을 증가시켰다. 지진의 규모가 작을 때 Pn이 보이지 않고 PmP가 초동파로 기록된 것처럼 보인다. 이러한 지진에서는 주어진 진앙거리에서 최소 주행시간이 걸리는 P파와 S파의 초동파만 사용한 기존의 진원요소 결정 방법과 본 연구에서 PmP와 SmS를 사용한 결과는 매우 큰 차이를 보인다.

• 전기학회논문지
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• 제59권6호
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• pp.1114-1119
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• 2010

This paper is concerned with an numerical analysis of electromagnetic wave propagation from randomly rough surfaces as a desert, sea surface and so on. We propose discrete ray tracing method (DRTM) for analysis of characteristics of wave propagation along one dimensional (1D) and two dimensional (2D) random rough surfaces. The point of the present method is to discretize not only rough surface but also ray tracing. This technique helps saving computer memories and does simplifying ray searching algorithm resulting in saving computation time. Numerical calculations are carried out for 1D and 2D random rough surfaces and electric field distributions are shown to check the effectiveness of the proposed DRTM.

• Journal of the Optical Society of Korea
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• 제11권4호
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• pp.162-172
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• 2007

Scanning Laser Optical Tweezers(SLOT) is an optical instrument frequently employed on a microscope with laser being delivered through its various ports. In most SLOT systems, a mechanical tilt stage with a mirror on top is used to dynamically move the laser focal point in two-dimensions. The focal point acts as a tweezing spot, trapping nearby microscopic objects. By adding a mechanical translational stage with a lens, SLOT can be expanded to work in three-dimensions. When two mechanical stages operate together, the focal point can address a closed three-dimensional volume that we call a workspace. It would be advantageous to have a large workspace since it means one can trap and work on multiple objects without interruptions, such as translating the microscope stage. However, previous studies have paid less consideration of the volumetric size of the workspace. In this paper, we propose a new method for designing a SLOT such that its workspace is maximized through optimization. The proposed method utilizes a matrix based ray tracing method and genetic algorithm(GA). To demonstrate the performance of the proposed method, experimental results are shown.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.143-148
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• 2005

The objective of this study is to estimate RF signal strength over sea and land surfaces. For this work we calculated scattering by land with DEM(Digital Elevation Model) and sea surface with RMS surface height. and we selected two area inland and sea shore as RX point. And for each area, we get VV-pol and HH-pol characteristic of scattering at 2.2GHz.

• 치과방사선
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• 제21권1호
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• pp.127-135
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• 1991

This study purports to make in consideration of the recent xeroradiographic development an exact analysis, by comparison, of conventional cephalometry and xeroradiographic cephalometry that are indispensably utilized in the field of orthodontics as a means of cephalometric measuring For that purpose attached to ten landmarks on a dry skull was a lead ball, a radio-opaque substance, and projected X-ray beam one time each by means of the two methods, and then ten times each without change of locations of the skull, in the state in which the lead ball was removed. These data were committed to ten dentists for tracing to determine a difference between the same kind of cephalometries. A computerized statistic analysis of the data shows findings, as follows: 1. Conventional cephalometry shows higher accuracy in Nasion, as compared with xeroradiographic cephalometry. 2. Xeroradiographic cephalometry is found more accurate in Anterior Nasal Spine, 'A' Point, Pogonion, Gonion, Porion, Prosthion and Orbitale than conventional cephalometry. 3. There is no difference between both methods in Basion. 4. At test between the two methods by all the dentists reveals that xeroradiographic cephalometry is more accurate than conventional cephalometry.

• 한국지진공학회논문집
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• 제1권1호
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• pp.19-24
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• 1997

파형분석에 의한 영월지진의 본진과 두 여진에 대하여 연구하였다. 한국자원연구소(KIGAM)에서 제공된 지진기록의 파형분석을 위하여 12개의 가능한 파형에 대하여 주시곡선과 두 점을 잇는 파선추적이 사용되었다. 영월지진의 파형분석 결과는 다음과 같은 특성을 보여준다. 1) 본진(규모 4.5)에서는 Pn파형이 명확이 보이지만 두 여진(규모 3.8과 2.5)에서는 Pn파형이 보이지 않는다. 2) 두 여진에는 Pg 혹은 PmP파형이 초동파로 도착한다. 3) 비록 콘라드 불연속면이 실제로 존재하더라도 지진기록에서 콘라드면과 관계되는 파형을 구분하기가 어렵다. 4) 경상분지밖에 위치하는 구례(GRE) 관측소의 지진기록은 Pn파형의 도착시간, 주파수 등에서 경상분지 내에 위치하는 관측소의 기록과 비교할 때 차이를 보인다.