• 한국정밀공학회지
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• 제22권12호
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• pp.100-107
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• 2005

The present work covers a new ray tracing scheme of an injection-molded plastic lens linked with finite element analysis fur injection molding processes. The traditional ray tracing schemes have been based on the assumption that optical property of the lens is homogeneous throughout the entire volume. However, this assumption is quite unrealistic for injection-molded plastic lenses since material properties vary at every point due to injection molding effects. In order to consider non-homogeneous property of a lens, a modified ray tracing method is proposed in connection with finite element analysis of injection molding. Through the analysis of the injection molding process, the distribution of refractive indices can be obtained. This information is then utilized in the proposed ray tracing scheme based on finite element meshes so as to take into account variation of the refractive indices. The effect of mold temperature is also investigated through finite element analysis, and the relevant optical quality is evaluated through the proposed ray tracing simulation.

• 한국전기전자재료학회논문지
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• 제27권3호
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• pp.162-166
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• 2014

We propose an analysis method of an autostereoscopic display system with lenticular lens array using finite ray-tracing method that is verified by the geometrical optics. In the present work, we adopt the cylinder equation for the mathematical expression of the lenticular lens. For the calculation of the direction cosine of the transmitted ray, we first calculate the refracting point at bottom of the lens and the direction cosine of the incident ray that propagating through the lens by the Snell's law, and then apply to finite ray-tracing method. Finally, we obtain the simulation results for the intensity distribution of the ray at optimal viewing distance. From these results, we confirm the realization of 3D image that exists separately according to the viewing position at an optimal viewing distance.

• 소성∙가공
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• 제16권1호
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• pp.25-30
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• 2007

The present study covers an integrated simulation method to evaluate optical performance of an aspheric plastic lens by connecting a finite element (FE) analysis of injection molding with a ray tracing simulation. Traditional ray tracing methods have based on the assumption that the optical properties of a lens are homogeneous throughout the entire volume. This assumption is to a certain extent unrealistic for injection-molded plastic lenses because material properties vary at every point due to the injection molding effects. To take into account the effects of the inhomogeneous optical properties of the molded lens, a new.ay tracing scheme is proposed in conjunction with a FE analysis of the injection molding. A numerical scheme is developed to calculate ray paths on every element layer with more realistic information of the refractive indices which can be obtained through the FE analysis. This information is then used to calculate the ray paths based on the FE mesh of which nodal points have unique index values. The proposed tracing scheme is implemented on the tracing of an aspheric lens, and its validity is ascertained through experimental verification.

• 소성∙가공
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• 제18권2호
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• pp.128-134
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• 2009

The present study covers an integrated simulation method to evaluate optical performance of an aspheric plastic lens by connecting an injection molding analysis with a ray tracing simulation. Traditional ray tracing methods have based on the assumption that the optical properties of a lens are homogeneous throughout the entire volume. This assumption is to a certain extent unrealistic for injection-molded plastic lenses because material properties vary at every point due to the injection molding effects. To take into account the effects of the inhomogeneous optical properties of the molded lens, a numerical scheme is developed to calculate the distribution of refractive index induced from the injection molding process. This index distribution is then reflected onto CODE $V^{(R)}$ simulation and used to calculate ray paths in inhomogeneous media. The proposed tracing scheme is implemented on the tracing of an aspheric lens for a mobile phone camera module.

• 오토저널
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• 제15권3호
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• pp.89-95
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• 1993

This paper presents the development of CAD system for the design of lens of the Turn Signal Lamp that can model and simulate its optical performance. The system consists of three main modules: skin surface modeling module, inner lens modeling module and optical performance simulation module. Skin surface geometry can be modeled by the input of data file and inner lens can be modeled by the input of only four parameter using its geometric characteristics. Also light distribution pattern, the barometer of optical performance is generated by means of finite ray tracing method. The system display modeled geometry, ray tracing and generated light distribution pattern.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.55-62
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• 2000

In constructing a synthetic seismogram using ray-tracing method a suite of ray-code is required to obtain a realistic seismogram which is similar to the actual seismogram or earthquake record under consideration. An infinite number of rays exist for any arbitrarily located source and receiver. One select only a finite number of such rays in computing a synthetic seismogram so their selection becomes important to the validity of the seismogram being generated. Missing certain important rays or an inappropriate selection of ray-codes in tracing rays may result in wrong interpretation of the earthquake record or seismogram. Automatic ray-code generation will eliminate such problems. In this study we have developed an efficient algorithm, with which one can generate systemastically all the ray-codes connecting source and receiver arbitrarily located. The result of this work will helpful in analysing multiple reflections in seismic data processing as well as simulating Lg wave and multiply reflected or converted phases in earthquake study.

• Nuclear Engineering and Technology
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• 제34권3호
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• pp.250-258
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• 2002

This Paper is to apply the well-established coarse mesh finite difference(CMFD) method to the method of characteristics(MOC) transport calculation as an acceleration scheme. The CMFD problem is first formulated at the pin-cell level with the multi-group structure To solve the cell- based multi-group CMFD problem efficiently, a two-group CMFD formulation is also derived from the multi-group CMFD formulation. The performance of the CMFD acceleration is examined for three test problems with different sizes including a realistic quarter core PWR problem. The CMFD formulation provides a significant reduction in the number of ray tracings and thus only about 9 ray tracing iterations are enough for the realistic problem. In computing time, the CMFD accelerated case is about two or three times faster than the coarse-mesh rebalancing(CMR) accelerated case.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2009년도 춘계학술발표회 논문집
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• pp.151-156
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• 2009

Forward modelling of ground penetrating radar (GPR) data is implemented using a new finite element ray tracing technique. The method is different from conventional ray tracing techniques in that the radar cross section of buried targets, the effective area of the receiving antenna, and the attenuation along the raypath are computed. The forward models are used to understand radar signatures measured across various ground structures which are important in detecting engineering hazards at construction sites, void spaces beneath simulated road beds, as well as a learning tool to avoid pitfalls in radargram interpretation. Forward modelling of radar data also can be used in predicting possible structures present at cultural property sites.

• 한국전자파학회논문지
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• 제10권1호
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• pp.133-141
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• 1999

본 논문에서는 광선추적기법에 근거한 3차원 실내 전파전파 예측모델을 제시한다. 본 모텔은 건물 실내에 산재되어 있는 가구, 집기 등의 모든 장애물을 고려하는 것 대선에 벽과 천장, 바닥 등의 대표적인 전파 장애 불만을 유한 두께와 유한 전도도를 갖는 슬랩으로 모댈링하여, 주요 전파현상을 고려함으로써 간결하면서도 정확하게 전파손실을 예측할 수 있는 모텔이다. 전파 광선들은 장애물과 부딪히면 거울 같은 반사와 투과를 하고 또 모서리에서는 회절되어 전파하는 것으로 고려되었다. 평연 장애물에서의 반사 및 투과 손실은 광선 추적기법을 사용하여 계산하였으며, 모서리에서의 회절손실은 유한 전도도 매질에 대한 UTD를 사용하여 계 산하였다 본 예측모델을 사용한 몇 경우에 대한 경로손실의 시율레이션 결과는 실측치와 잘 일치하는 것을 보여준다.

• Ocean and Polar Research
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• 제36권3호
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• pp.225-234
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• 2014

The 2011 Tohoku earthquake triggered extremely destructive tsunami waves which propagated over the Pacific Ocean, Atlantic Ocean through Drake Passage and Indian Ocean respectively. A total of 10 tide-gauge records collected from the UNESCO/IOC site were analyzed through a band-pass digital filtering device to examine the observed tsunami characteristics. The ray tracing method and finite-difference model with GEBCO 30 arc second bathymetry were also applied to compare the travel times of the Tohoku-originated tsunami, particularly at Rodrigues in the Indian Ocean and King Edward Point in the Atlantic Ocean with observation-based estimates. At both locations the finite-difference model produced the shortest arrival times, while the ray method produced the longest arrival times. Values of the travel time difference however appear to be within tolerable ranges, considering the propagation distance of the tsunami waves. The observed tsunami at Rodrigues, Mauritius in the west of the Madagascar was found to take a clockwise travel path around Australia and New Zealand, while the observed tsunami at King Edward Point in the southern Atlantic Ocean was found to traverse the Pacific Ocean and then passed into the Atlantic Ocean through the Drake Strait. The formation of icebergs captured by satellite images in Sulzberger in the Antarctica also supports the long-range propagation of the Tohoku-originated tsunami.