• Journal of the Korean Solar Energy Society
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• v.31 no.3
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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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.7
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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.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.5
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• pp.57-61
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• 2001

This study introduces an algorithm for determination of hypocentral parameters using phase analysis and two-point ray tracing to enhance accuracy and stability of computations. When the magnitude of earthquake is relatively small(usually $m_{b}$<3.2), the PmP phase which looks like the first arrival phase may be observed without observing the Pn phase. In this case, the hypocentral parameters calculated by the existing method using the first arrival of P and S phases and by the method developed in this study using PmP and SmS phases show large differences. The computational results of determination of hypocentral parameters for actual earthquake events show that this method gives much smaller rms errors than the existing methods do.o.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.8
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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.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.10a
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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.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.6
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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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• v.11 no.4
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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.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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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.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.21 no.1
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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.

• Journal of the Earthquake Engineering Society of Korea
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• v.1 no.1
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• pp.19-24
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• 1997

The seismic of the main shock and two after shocks of the Yeongwol Earthquake are studied based on the phase analysis. The travel time curves and two point ray tracing with 12 different possible phases are used to analyze the phases of the records, which were provided by KIGAM seismic network. The results of phase analysis of the Yeongwol Earthquake show the characteristics as follows 1) The main shock ($M_s$=4.5) clearly shows Pn phase but two after shocks ($M_s$=3.8 and $M_s$=2.5) do not show Pn phase. 2) The Pg PmP looks as first arrival phase in the after shock records whose epicentral distance is smaller or larger than 145 km, 3). It is very difficult to identify the phases in the seismic records, which ae related to the Conrad discontinulty, even if the Conrad discontiulty exists. 4) The record of GRE station located outside of the Kyeongsan Basin shows different arrival time of Pn phase, P-S duration time and frequency comared with those of the other stations located within the Kyeongsan Basin.