• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.694-698
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• 2006

This paper presents an optimal design process using beads on a body panel to improve interior noise of a passenger vehicle. Except modification of structural members, it is difficult to find effective countermeasures that can work for the intermediate frequency range from 100 Hz to 300 Hz which lies between the booming and low medium frequency. In this study, it is a major goal to find additional counter-measures for this intermediate frequency range by performing optimal design of beads on body panels. The proposed method for design optimization consists of 4 sub-steps, that is, a) problem definition, b) cause analysis, c) countermeasure development and d) validation. The objective function is minimization of interior noise level. The major design variables are the geometrical shape of a bead and combination of beads on the critical panels. Sensitivity analysis and optimization are performed according to the predefined process for an optimal design. It is verified that the proposed design decreases the level of noise transfer function above 5 dB.

• Computers and Concrete
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• 제13권3호
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• pp.309-323
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• 2014

Based on the compositions and structures of cement-based materials, the geometrical models of the tortuosity of transport paths in hardened cement pastes, mortar and concrete, which are associated with the capillary porosity, cement hydration degree, mixture particle shape, aggregate volume fraction and water-cement ratio, are established by using a geometric approach. Numerical simulations are carried out to investigate the effects of material parameters such as water-cement ratio, volume fraction of the mixtures, shape and size of aggregates and cement hydration degree, on the tortuosity of transport paths in hardened cement pastes, mortar and concrete. Results indicate that the transport tortuosity in cement-based materials decreases with the increasing of water-cement ratio, and increases with the cement hydration degree, the volume fraction of cement and aggregate, the shape factor and diameter of aggregates, and the material parameters related to cement pastes, such as the water-cement ratio, cement hydration degree and cement volume fraction, are the primary factors that influence the transport tortuosity of cement-based materials.

• 한국공간구조학회논문집
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• 제16권4호
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• pp.45-52
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• 2016

The single layer latticed domes have attracted many designers and researchers's attention all of the world, because these structures as spatial structure are of great advantage in not only mechanical rationality but also function, fabrication, construction and economic aspect. But single layer latticed domes are apt to occur the unstable phenomena that are called "buckling" because of the lack of strength of members, instability of structural shape, etc. In the case of latticed dome, there are several types of buckling mode such as overall buckling, local buckling, and member buckling according to the shape of dome, section type of member, the size of member, junction's condition of member and so on. There are many methods to increase the buckling strength of the single layer latticed dome, that is, with the change of geometrical shape of dome, the reinforcement of buckled member, etc. Therefore, the purpose of this study is to verify the reinforcement effect of buckled member when designers reinforce the buckled member to increase the buckling strength of single layer latticed dome with 3-way grid.

• 한국컴퓨터정보학회논문지
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• 제9권4호
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• pp.85-91
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• 2004

최근 들어 인간의 의지를 컴퓨터에 전달하기 위한 수단으로 컴퓨터 시각기반 방식으로 제스처를 인식하고자 하는 연구가 널리 진행되고 있다. 제스처 인식에서 가장 중요한 이슈는 알고리즘의 단순화와 처리 시간의 감소이다. 이러한 문제를 해결하기 위하여 본 연구에서는 기하학적 집합론에 근거하고 있는 수학적 형태론을 적용하였다. 본 논문에서 제안한 알고리즘의 키 아이디어는 형태론적 형상분해를 적용하여 얻은 원시형상 요소들의 중심점을 연결하는 궤적을 추적하는 것이다. 핸드 제스처 시퀀스의 중심점 궤적은 핸드 제스처의 형상에 관련된 중요한 정보를 내포하고 있다. 이러한 특징에 근거하여 본 연구에서는 원시형상 요소들의 중심점 궤적과 직접적으로 관련되는 체인코드 에지벡터로부터 형상의 특징벡터를 계산하여 핸드 제스처 시퀀스를 인식할 수 있는 알고리즘을 제안하고, 실험을 통하여 그 유용성을 증명하였다.

• International Journal of Precision Engineering and Manufacturing
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• 제8권3호
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• pp.64-70
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• 2007

Of all the rapid tooling (RT) methods currently available, thick-layer laminated tooling is the most suitable for large-scale, low-cost dies and molds. Currently, the determination of a lamina's contour or profile and the associated slicing algorithms are based on existing rapid prototyping (RP) data manipulation technology. This paper presents a new adaptive slicing algorithm developed exclusively for profiled edge laminae (PEL) tooling PEL tooling is a thick-layer RT technique that involves the assembly of an array of laminae, whose top edges are simultaneously profiled and beveled using a line-of-sight cutting method based on a CAD model of the intended tool surface. The cutting profiles are based on the intersection curve obtained directly from the CAD model to ensure geometrical accuracy. The slicing algorithm determines the lamina thicknesses that minimize the dimensional error using a new tool shape error index. At the same time, the algorithm considers the available lamination thicknesses and desired lamina interface locations. We demonstrate the new slicing algorithm by developing a simple industrial PEL tool based on a CAD part shape.

• Journal of Biosystems Engineering
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• 제37권2호
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• pp.90-99
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• 2012

Purpose: This study was conducted to investigate the optimal sorting factors in establishing an efficient sorting technology for brown rice. Methods: The brown rice varieties used in this study were Il Pum, Chu Cheong, Dong Jin, Un Gwang, Nam Pyeong, and Dae An. These were classified into whole grain, unriped grain, and green dead rice. The shape factors were analyzed based on length, width and thickness of the grains. Results: The results revealed that the maximum length among whole grain, unriped grain, and green dead rice was observed in Dae An variety while Chu Cheong variety showed the minimum. Further more, Il Pum brown rice showed the maximum width while Dong Jin variety showed the minimum. In the case of thickness, the maximum was observed in Un Gwang variety and that of the minimum among Nam Pyeong variety for both whole grain and unriped grain. Conclusions: The length and width can be used as determinants in sorting factors of whole grain and green dead rice, and the thickness can be considered as optimum sorting factor of whole grain and unriped grain.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 춘계학술대회 논문집
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• pp.16-19
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• 2001

Rapid Prototyping (RP) and Rapid Tooling (RT) were introduced to reduce time-to-market and cost by shortening not only the development phase but also the production phase of the manufacturing process. RP generally builds up a prototype layer by layer, rapidly generating a fully three-dimensional free form shape. RT enables the manufacture of production tools. The integration of RP and RT has the potential for rapid net shaping of thee-dimensional parts, which have geometrical complexity. In this study, net shaping techniques for making three-dimensional parts using RP and RT are described and a sample part are shown. A three-dimensional metal part is manufactured by a new RP process, Variable Lamination Manufacturing by using Expandable Polystyrene Foam (VLM-S), and its application to RT for making a clover punch. In addition, we discussed the technology fusion between metal forming md RP/RT.

• 한국양봉학회지
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• 제33권4호
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• pp.227-237
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• 2018

The majority parasitic bee mites of Thailand in genus Tropilaelaps are infesting colonies of native bees (Apis dorsata) and introduced bees (A. mellifera). The investigation aims to study morphological and genetic variation of Tropilaelaps mites infected different hosts. Adult mites were collected from honey bee brood throughout Thailand. Traditional and geometrical morphometrics were measured on photograph by using TPS program. Additional, COI gene variations were examined by PCR-RFLP and nucleotides sequencing. Tree of mites relationships were constructed by NJ and MP assumptions. Morphometric results indicated T. mercedesae were major species infesting on A. dorsata and A. mellifera. Mophological variation represented at anal and epigynial plate, which the shape of the anal plate apex margin has been key character to identify between T. mercedesae (bell to blunt shape) and T. koenigerum (pear shape). However, the discriminant analysis suggested that geometric results were potential to classify Thai Tropilaelaps populations from different hosts better than traditional morphometric. Otherwise, PCR-RFLP clearly detected the site of Dra I and Xba I digestion of Thai Tropilaelaps morphotypes. The COI sequences of T. koenigerum were founded infesting only A. dorsata in Thailand and four sequences that related to the Thai T. mercedesae morphotypes. The NJ and MP tree were clearly classified Thai Tropilaelaps species which were suggested both from morphological and molecular analysis. This information might be basically of taxonomic status, but this should have implication for controlling these mites in Thailand and other countries.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.86-101
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• 2021

This study examined the effects of buoy shape and Nonlinear Froude-Krylov force (NFK) on a heaving-buoy-type Wave Energy Converter (WEC). Based on the Maclaurin expansion, the theoretical solutions of the NFK were derived for three different buoy shapes; hemispheric buoy, circular vertical cylinder, and truncated conical cylinder. A hydraulic power take-off system was adopted, and the latching control strategy was applied to maximize the extracted power from the WEC. The nonlinear effects of the Froude-Krylov force and restoring force on the heaving point absorber were investigated by comparing the heave Response Amplitude Operator (RAO) and time-averaged power extraction. The results showed that the conventional linear analyses were overestimated by up to 50% under the high amplitude wave condition. The latching control strategy was the most effective when peak wave period of regular or irregular wave was 0.4-0.45 times the heave natural period of the buoy.

• Structural Engineering and Mechanics
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• 제85권2호
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• pp.147-161
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• 2023

Based on the ideas of variational differential quadrature (VDQ) and finite element method (FEM), a numerical approach named as VDQFEM is applied herein to study the large deformations of plate-type structures under static loading with arbitrary shape hole made of functionally graded graphene platelet-reinforced composite (FG-GPLRC) in the context of higher-order shear deformation theory (HSDT). The material properties of composite are approximated based upon the modified Halpin-Tsai model and rule of mixture. Furthermore, various FG distribution patterns are considered along the thickness direction of plate for GPLs. Using novel vector/matrix relations, the governing equations are derived through a variational approach. The matricized formulation can be efficiently employed in the coding process of numerical methods. In VDQFEM, the space domain of structure is first transformed into a number of finite elements. Then, the VDQ discretization technique is implemented within each element. As the last step, the assemblage procedure is performed to derive the set of governing equations which is solved via the pseudo arc-length continuation algorithm. Also, since HSDT is used herein, the mixed formulation approach is proposed to accommodate the continuity of first-order derivatives on the common boundaries of elements. Rectangular and circular plates under various boundary conditions with circular/rectangular/elliptical cutout are selected to generate the numerical results. In the numerical examples, the effects of geometrical properties and reinforcement with GPL on the nonlinear maximum deflection-transverse load amplitude curve are studied.