• 정보처리학회논문지D
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• 제10D권2호
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• pp.211-220
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• 2003

지리정보시스템은 3차원 위상정보를 표현함으로써 사용자에게 정확하고 정교한 서비스를 제공한다. 이 때에 3차원 위상정보연산을 위해 차원변경방식과 서로 이질적인 공간모델을 사용해야 하는데, 이 방식을 사용할 때는 공간 연산이 어려울 뿐 아니라 서로 호환성이 부족한 문제가 발생한다. 따라서 이 논문에서는 이 문제를 해결하기 위하여 2차원 공간 객체 모델을 수용하는 3차원 공간 객체 모델을 제안하였고, 타당성을 보이기 위하여 구현하여, 그 실행을 보였다. 3차원 공간 위상 관계 연산자를 위하여 DE-9IM 방식을 3차원 개념으로 정의한 DE-9IM을 이용해서 설계하였고, 객체지향 개념을 지원하는 컴포넌트 환경에서 3차원 공간 위상 연산자를 구현하였다. 이 논문에서 제안된 3차원 공간 위상 연산자는 타 시스템과의 상호 운용성을 보장하며, 구현된 공간 위상 관계 연산을 이용하여, 3차원 공간 객체에 대한 효율적인 공간 질의를 수행할 수 있다.

• Wind and Structures
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• 제25권6호
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• pp.537-549
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• 2017

In this study, the turbulent flow around a bluff body for different wind velocities was investigated numerically by using its two- and three-dimensional models. These models were tested to verify the validity of the simulation by being compared with experimental results which were taken from the literature. Variations of non-dimensional velocities in different positions according to the bluff body height were analysed and illustrated graphically. When the velocity distributions were examined, it was seen that the results of both two- and three-dimensional models agree with the experimental data. It was also seen that the velocities obtained from two-dimensional model matched up with the experimental data from the ground to the top of the bluff body. Particularly, compared to the front part of the bluff body, results of the upper and back part of the bluff body are better. Moreover, after comparing the results from calculations by using different models with experimental data, the effect of multidimensional models on the obtained results have been analysed for different inlet velocities. The calculation results from the two-dimensional (2D) model are in satisfactory agreement with the calculation results of the three-dimensional model (3D) for various flow situations when comparing with the experimental data from the literature even though the 3D model gives better solutions.

• 한국의류학회지
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• 제42권3호
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• pp.503-515
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• 2018

In this research, the three-dimensional structural and colorimetrical modeling of yarn-dyed woven fabrics was conducted based on the Kubelka-Munk theory (K-M theory) for their accurate color predictions. In the K-M theory for textile color formulation, the absorption and scattering coefficients, denoted K and S, respectively, of a colored fabric are represented using those of the individual colorants or color components used. One-hundred forty woven fabric samples were produced in a wide range of structures and colors using red, yellow, green, and blue yarns. Through the optimization of previous two-dimensional color prediction models by considering the key three-dimensional structural parameters of woven fabrics, three three-dimensional K/S-based color prediction models, that is, linear K/S, linear log K/S, and exponential K/S models, were developed. To evaluate the performance of the three-dimensional color prediction models, the color differences, ${\Delta}L^*$, ${\Delta}C^*$, ${\Delta}h^{\circ}$, and ${\Delta}E_{CMC(2:1)}$, between the predicted and the measured colors of the samples were calculated as error values and then compared with those of previous two-dimensional models. As a result, three-dimensional models have proved to be of substantially higher predictive accuracy than two-dimensional models in all lightness, chroma, and hue predictions with much lower ${\Delta}L^*$, ${\Delta}C^*$, ${\Delta}h^{\circ}$, and the resultant ${\Delta}E_{CMC(2:1)}$ values.

• 품질경영학회지
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• 제31권4호
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• pp.219-225
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• 2003

Two­dimensional warranty data can be modelled using two different approaches： two­dimensional point process and one­dimensional point process with usage as a function of age. The first approach has three different models. First of all, bivariate model is appealing but is not appropriate for explaining warranty claims. Next, the rest of the two models (marked point process, and counting and matching on both directions independently) are more appropriate for explaining warranty claims. However, the second one (counting and matching on both directions independently) assumes that the two variables (variables representing the two­dimensions) are independent. Last of all, one­dimensional point process with usage as a function of age is also promising to explain the two­dimensional warranty claims. But the models or variations of them need more investigation to be applicable to real warranty claim data.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.885-890
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• 2002

As Geographic Information Systems represents three-dimensional topological Information, the systems provide accurate and delicate services for user. In order to execute three-dimensional topological operations, a dimensional transformation and heterogeneous spatial models should be used. However, the existing systems that use the dimensional transformation and the heterogeneous models, are not only difficult to operate the spatial operators, but also happened to support non- interoperability. Therefore, in order to support the spatial operation as well as interoperability between dimensions, we propose three-dimensional spatial operators for the proposed models. We defined the three-dimensional spatial operators prior to designing the proposed model. We also implemented the operators of proposed model and evaluated the implemented model on the component environment. Finally, the proposed model is able to not only support interoperability among systems but also execute spatial queries efficiently on three-dimensional spatial objects.

• Structural Engineering and Mechanics
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• 제69권5호
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• pp.499-509
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• 2019

While the wheel flat is an asymmetrical phenomenon in the railway, majority of researches have used two-dimensional models in the investigation of the effect of wheel flat on the wheel rail forces. This is due to the considerably low computational costs of two dimensional (2D) models although their reliability is questionable. This leaves us with the question of "what is the optimum modeling technique?". It is addressed in this research. For this purpose, two and three dimensional numerical models of railway vehicle/track interaction were developed. The three dimensional (3D) model was validated by comparisons of its results with those obtained from a comprehensive field tests carried out in this research and then, the results obtained from the 2D and 3D models were compared. The results obtained indicate that there are considerable differences between wheel/rail forces obtained from the 2D and 3D models in the conditions of medium to large wheel-flats. On the other hand, it was shown that the results of the 2D models are reliable for particular ranges of vehicle speed, railway track stiffness and wheel-fats lengths and depths. The results were used to draw a diagram, which presents the optimum modeling technique, compromising between the costs and accuracy of the obtained results.

• 대한수학회보
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• 제58권5호
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• pp.1109-1127
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• 2021

We study the long-term dynamics for a family of incompressible three-dimensional Leray-α-like models that employ the spectral fractional Laplacian operators. This family of equations interpolates between incompressible hyperviscous Navier-Stokes equations and the Leray-α model when varying two nonnegative parameters 𝜃₁ and 𝜃₂. We prove the existence of a finite-dimensional global attractor for the continuous semigroup associated to these models. We also show that an operator which projects the weak solution of Leray-α-like models into a finite-dimensional space is determining if it annihilates the difference of two "nearby" weak solutions asymptotically, and if it satisfies an approximation inequality.

• 한국지역사회생활과학회지
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• 제22권1호
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• pp.95-102
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• 2011

The purpose of this study was to examine the development of detailed description for drawing houses according to the shapes of lines, and dimensions of space from 4 to 5 years-old children. Participants were 76 children from a daycare center in Busan, Korea. Each child was asked to draw 4 different houses according to the shapes of lines and dimensions of space, such as: straight lines and 2-dimensional pictures straight lines and 3-dimensional Models, curved lines and 2-dimensional pictures and curved lines and 3-dimensional models. The children's drawings were scored based on a "detailed description rating table" which consisted of 10 items. Summarizing the overall results, first, 5 year-olds scored significantly higher than 4 year-olds in the detailed description of 4 different house models. Second, the houses with straight lines scored significantly higher than those with curved lines in the detailed description. Third, there were no significant differences between 2-dimensional houses and those of 3-dimensional models in the detailed description. These results suggest that the detailed description of young children's drawing is developed as children grow older, and drawing with straight lines are earlier developed than curved lined drawings.

• 치위생과학회지
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• 제14권1호
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• pp.15-21
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• 2014

본 연구에서는 구강으로부터 채득된 인상체를 스캐닝하여 디지털 모형을 제작하였을 때 제작된 디지털 모형의 체적 안정성을 평가하고자 하였다. 그리하여 환자의 구강을 가정한 상악 모형을 본 모형으로 채택하였다. 본 모형과 동일한 증례의 연구 모형을 치과용 석고를 이용하여 총 20개의 석고 모형을 제작하였다. 제작된 연구 모형 20개를 치과용 기성 트레이와 두 종류의 치과용 인상재를 이용하여 20개 연구 모형을 대상으로 20개의 인상을 채득하였다. 채득된 20개의 인상체를 치과용 스캐너로 스캐닝하는 방식으로 디지털 모형으로 변환하였다. 체적 안정성을 평가하기 위하여 6개의 대표 지점을 선정한 뒤 디지털 모형과 함께 디지털 모형의 근간인 석고 모형을 계측하였다. 그 결과 계측된 모든 부위에서 디지털 모형이 석고 모형보다 체적이 작은 것으로 조사되었고, 이는 통계적으로 유의하였다(p<0.05). 이러한 결과들로 추론하여 보았을 때 환자의 구강으로부터 채득된 인상체를 스캐닝하여 제작한 디지털 모형의 체적은 환자의 구강보다 작다는 것을 알 수 있었다. 그러나 이 차이는 미비한 것으로 여러 선행 연구 결과들을 근거로 하였을 때 임상적으로 허용이 가능한 것으로 생각된다.

• International Journal of Automotive Technology
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• 제5권3호
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• pp.165-172
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• 2004

Phenomenological models for direct injection diesel engine emissions including NO, soot, and HC were implemented into a full engine cycle simulation and validated with experimental data obtained from representative heavy-duty DI diesel engines. The cycle simulation developed earlier by Jung and Assanis (2001) features a quasi-dimensional, multi-zone, spray combustion model to account for transient spray evolution, fuel-air mixing, ignition and combustion. In this study, additional models for HC emissions were newly implemented and the models for NO, soot, and HC emissions were validated against experimental data. It is shown that the models can predict the emissions with reasonable accuracy. However, additional effort may be required to enhance the fidelity of models across a wide range of operating conditions and engine types.