• Journal of Computational Design and Engineering
• /
• v.3 no.4
• /
• pp.322-329
• /
• 2016

The advent of high-performance terrestrial laser scanners has made it possible to capture dense point-clouds of engineering facilities. 3D shape acquisition from engineering facilities is useful for supporting maintenance and repair tasks. In this paper, we discuss methods to reconstruct box shapes and polygonal prisms from large-scale point-clouds. Since many faces may be partly occluded by other objects in engineering plants, we estimate possible box shapes and polygonal prisms and verify their compatibility with measured point-clouds. We evaluate our method using actual point-clouds of engineering plants.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2003.09a
• /
• pp.46-49
• /
• 2003

A concept of fuzzy wavelets is proposed by a fuzzification of morphological wavelets. In the proposed fuzzy wavelets, analysis and synthesis schemes can be formulated as the operations of fuzzy relational calculus. In order to perform an efficient compression and reconstruction, an alphaband is also proposed as a soft thresholding of the wavelets. In the image compression/reconstruction experiment using test images extracted Standard Image DataBAse (SIDBA), it is confirmed that the root mean square error (RMSE) of the proposed soft thresholding is decreased to 87.3％ of the conventional hard thresholding.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2003.09a
• /
• pp.488-491
• /
• 2003

A motion compression method by min s-norm composite fuzzy relational equations (dual-MCF) is proposed, where a motion sequence is divided into intra-pictures (I-pictures) and predictive-pictures (P-pictures). The I-pictures and the P-pictures are compressed by using uniform coders and non-uniform coders, respectively. A design method of non-uniform coders is proposed to perform an efficient compression and reconstruction of the P-pictures, based on the dual overlap level of fuzzy sets and a fuzzy equalization. An experiment using 10 P-pictures confirms that the root means square errors of the proposed method is decreased to 82.9％ of that of the uniform coders, under the condition that the compression rate is 0.0055. An experiment of motion compression and reconstruction is also presented to confirm the effectiveness of the dual-MCF based on the non-uniform coders.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.10
• /
• pp.1848-1853
• /
• 2006

In this paper, we propose a method to reconstruct resolution-improved 3D images computationally based on lenslet array model in integral imaging technique and analyze its performance. While conventional view-point reconstruction method has low resolution based on pinhole array model, the proposed method can obtain resolution-improved 3D images because of extracting multiple pixels from elemental images by use of lenslet way model. To show the usefulness of proposed method, we perform computational experiments and present its results.

• Journal of computational fluids engineering
• /
• v.12 no.3
• /
• pp.41-46
• /
• 2007

Dynamic behavior of immiscible gas bubble attached to the wall in channel flow plays very important role in many engineering applications. Special attention has been paid to micro direct methanol fuel cell(${\mu}$DMFC) where surface tension becomes dominant factor with minor gravitational effect due to its reduced size. Therefore, displacement of $CO_2$ bubble generating on a cathode side in ${\mu}$DMFC can be very difficult and efficient removal of $CO_2$ bubbles will affect the overall machine performance considerably. We have focused our efforts on studying the dynamic behavior of immiscible bubble attached to the one side of the wall on 2D rectangular channel subject to external shear flow. We used Level Contour Reconstruction Method(LCRM) which is the simplified version of front tracking method to track the bubble interface motion. Effects of Reynolds number, Weber number, advancing/receding contact angle and property ratio on bubble detachment characteristic has been numerically identified.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.757-760
• /
• 2008

In this paper, an improved computational integral imaging reconstruction (CIIR) is proposed. The proposed method can highly enhance the viewing quality of reconstructed image. To show the feasibility of proposed method, some experiments are performed and the results are compared and discussed with those of the conventional method.

• Journal of computational fluids engineering
• /
• v.14 no.1
• /
• pp.18-23
• /
• 2009

A novel adaptive mesh refinement(AMR) strategy based on the Moment-of-Fluid(MOF) method for volume-tracking dynamic interface computation is presented. The Moment-of-Fluid method is a new interface reconstruction and volume advection method using volume fraction as well as material centroid. The adaptive mesh refinement is performed based on the error indicator, the deviation of the actual centroid obtained by interface reconstruction from the reference centroids given by moment advection process. Using the AMR-MOF method, the accuracy of volume-tracking computation with evolving interfaces is improved significantly compared to other published results.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2011.04a
• /
• pp.273-276
• /
• 2011

표면의 물성은 표면효과를 고려한 나노 스케일의 구조물의 기계적 거동 해석에 있어서 필수적인 요소이다. 이러한 해석을 위한 방법론 중 surface relaxation model을 이용하여 박막의 표면 물성을 계산하는 방법은 이미 FCC 모델에서는 검증된 바 있으나, 동일한 방법론을 diamond 구조를 가지는 실리콘에 일괄적으로 적용할 수는 없다. 이는 FCC 구조를 갖는 금속과는 달리 실리콘이 공유결합 물질이라는 점과, 박막표면에서 다양한 surface reconstruction이 가능하다는 점, 그리고 실리콘의 diamond lattice가 FCC lattice에 비해 추가적인 자유도가 존재한다는 점으로부터 기인한다. 본 논문에서는 이와 같은 조건을 고려하여 Si 박막의 표면 물성을 해석하기 위한 surface relaxation 모델을 제시한다.

• Journal of the Optical Society of Korea
• /
• v.20 no.3
• /
• pp.363-367
• /
• 2016

In this paper, we present a resolution-enhanced computational integral imaging reconstruction method by using boundary folding mirrors. In the proposed method, to improve the resolution of the computationally reconstructed 3D images, the direct and reflected light information of the 3D objects through a lenslet array with boundary folding mirrors is recorded as a combined elemental image array. Then, the ray tracing method is employed to synthesize the regular elemental image array by using a combined elemental image array. From the experimental results, we can verify that the proposed method can improve the visual quality of the computationally reconstructed 3D images.

• Korean Journal of Computational Design and Engineering
• /
• v.10 no.6
• /
• pp.392-401
• /
• 2005

2D CAD is being replaced by 3D CAD to improve efficiency of product design and manufacturing. Therefore, converting legacy 2D drawings into 3D solid models is required. CSG based approaches construct solid models from orthographic views more efficiently than traditional B-rep based approaches. A major limitation of CSG based approaches has been the limited domain of objects that can be handled. This paper aims at extending the capabilities of CSG based approaches by proposing hint-based recognition of interacting solids of revolution which can handle interacting solids of revolution as well as isolated solids of revolution.