• Journal of Advanced Marine Engineering and Technology
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• v.35 no.8
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• pp.1055-1062
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• 2011

The purpose of this study is to develop the shape of photocatalyst-coated module for improve the IAQ, which is installed at inside of ductwork and detachable. Including 3 column types(square, circle, diamond) and 2 fin types(diamond and square), totally 5 types are previously declared for numerical analysis and comparison, 5 types are. As the results of numerical analysis, almost the velocity varied at the range of ${\pm}0.3m$ from the module, except the Type A-3(diamond column type) which is affected to ${\pm}0.4m$ range and shows the biggest velocity differences. Among the 5 types, the diamond fin type(Type B-1) is analyzed as the most stable in velocity. And the results of local pressure drop show that the difference of pressure coefficient of Type B-1 is computed as 0.59, and that of Type A-3 is 2.44. Meanwhile, from the effect analysis of the number of module, the flow conflict happens and the pressure difference between before and after the module increases if there are over 3 modules inserted.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.5
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• pp.435-442
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• 2017

A catadioptric optical system produces images by refraction and reflection. To improve the image quality, the shape of the secondary mirror supporters should be determined to ensure that the centering error and tilt of secondary mirror are very small, and the main mirror receives the maximum amount of light. Furthermore, random acceleration vibration has a severe effect on the optical system for observation reconnaissance. In order to obtain the best design under these circumstances, the volume of the secondary mirror supporter must be minimized while satisfying the constraints expressed in standard deviations of the centering error and tilt. It is difficult to analytically calculate the design sensitivities of the standard deviations, because they are statistically defined. Hence, after their second-order regression equations were determined using a response surface methodology, an optimal geometric design was obtained. As a result, it was found that the method proposed in this paper, which included a random vibration analysis, was effective in obtaining the optimal design for a secondary mirror supporter with robustness.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.8
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• pp.855-860
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• 2011

We numerically simulated a dissolved air flotation (DAF) tank to predict the performance of the pilot facility. The flow was assumed to be two-dimensional and two-phase. The velocity distributions in the separation zones of differently shaped DAFs were compared to find the effect of the shape on the performance. The results showed that the typical flow pattern that appeared in a well-designed DAF-tank was generated in the separation zone of the base model. This flow pattern could be maintained while the baffle height was sufficiently tall regardless of the other geometric parameters. However, the baffle height and angle, the contact zone width, and the perforated plate affected the uniformity of the downward flow in the separation zone. Except for the baffle height, the base model used in this study showed a better uniformity of downward flow than did other models with different geometric parameters.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.4
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• pp.393-400
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• 2020

Axial and lateral behavior of helical piles is generally influenced by number, diameter, helix pitch, and locations of helices. In this study, axial and horizontal behavior of helical piles with three helices was investigated varying helices' locations, diameter, and pitch. Especially, due to the spiral shapes of helices, the effect of lateral load directions at pile heads on their lateral behavior was investigated. Axial load test of small-scale helical pile was conducted in laboratory, and its results were compared with numerical analysis results of the same model for cross check of validity of both results. Furthermore, diverse numerical analyses were performed for different shapes of helical piles. Consequently, it was found that, for the given analysis conditions, the helix diameter was the most influential factor on the horizontal and vertical behavior of helical piles.

• Journal of the Korean Society for Advanced Composite Structures
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• v.1 no.2
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• pp.14-19
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• 2010

Theories for advanced composite structures are too difficult for such design engineers for construction and some simple but accurate enough methods are necessary. The senior author has reported that some laminate orientations have decreasing values of $D_{16}$, $B_{16}$, $D_{26}$ and $B_{26}$ stiffnesses as the ply number increases. For such plates, the fiber orientations given above behave as specially orthotropic plates and simple formulas developed by the senior author. Most of the bridge and building slabs on girders have large aspect ratios. For such cases further simplification is possible by neglecting the effect of the longitudinal moment terms(Mx) on the relevant partial differential equations of equilibrium. In this paper. the influence of the aspect ratio on the natural frequency of the composite laminated plates is studied and it is concluded that the method used is sufficiently accurate for engineering purposes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.3
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• pp.211-219
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• 2008

A three-dimensional inviscid flow solver has been developed based on unstructured meshes for the investigation of the effect of the external stores on the tail surfaces of a generic fighter aircraft. The numerical method is based on a vertex-centered finite-volume discretization and an implicit point Gauss-Seidel time integration. The calculations were made for a steady flow and the computed results were compared with experimental data to validate the flow solver. An unsteady time-accurate computation of the generic fighter aircraft with external stores at transonic flight conditions showed that the external stores cause unsteady loading on the horizontal tail surface due to the mutual interference between their wake and the horizontal tail surface. It was shown that downward deflection of the trailing edge flap significantly reduces the undesirable interference effect.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.9
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• pp.5419-5424
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• 2014

A weld scallop is a small quadrant or half circle type hole installed in the weld line cross area for easy welding operation. Many types of T-bars with a scallop can be welded in a block assembly stage in shipbuilding. The difficulties arise from the fact that scallops are to be filled by build-up welding after welding of the cross line is complete. In this study, a non-scallop block joint welding method was developed using special type CBM (ceramic backing material). The wedge shaped CBM was devised to insert a CBM into just the V groove of weld line cross area without weld scallop. A saw-toothed shape was adopted for easy cutting of the unnecessary part in the CBM fitting process. The applicability of the developed method was verified through welding experiments based on the yard welding conditions.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.10
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• pp.796-800
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• 2009

Currently, there are many software tools that can generate 3D human figure models and animations based on the advancement of computer graphics technology. However, we still have problems in interoperability of human data models in different applications because common data models do not exist. To address this issue, the Web3D Consortium and the ISO/IEC JTC1 SC24 WG6 have developed the H-Anim standard. However, H-Anim does not include human motion data formats although it defines the structure of a human figure. This research is intended to obtain interoperable human animation by defining the data for human motions in H- Anim figures. In this paper, we describe a syntactic method to define motion data for the H-Anim figure and its implementation. In addition, we describe a method of specifying motion parameters necessary for generating animations by using an arbitrary character model data set created by a general graphics tool.

• Journal of Korean Society of Steel Construction
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• v.13 no.5
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• pp.547-556
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• 2001

This study presents new method in which to derive the constraint coefficient from the quantity of angular deformation by welding measured by varying the shape of welded joints and the magnitude of constraints by varying the shape of welded joints and the magnitude of constraints by experiment and from the result analyzed by elastic FEM method and then to decide equivalent load with it The numerical analysis results by this new method verified the validity by agreeing with the experimental result on specimen. In addition These results are applicable to the prediction of the quantity of welding deformation for large structures regardless of the size and the shape While in the effects of the constraints based on the shape of welded joints in the case of Butt welding when the constraint coefficients are not considered the deformed quantity is produced larger than one by the experiment and consequently is largely affected by the constraints But in the case of Fillet welding the deformed quantity is seldom affected regardless of considering the constraint coefficients or not.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.7
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• pp.871-877
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• 2004

In this paper, for manufacturing a custom-made shoes, shape of foot acquired three-dimensional measurement device which makes shoe-last data for needing a custom-made shoes is founded on artificial intelligence technique and it shows method restoring to the original shape in optimized state. the developed system for this study is based on PC which uses existing three dimensional measurement method. And it gains shoe-last and data of foot shape going through 8 CCD(Charge Coupled Device) Which equipped top and bottom, right and left sides and 4 lasers which also equipped both sides and upper and lower sides. The acquired data are processed image processing algorithm using artificial intelligence technique. And result of data management is better quality of removing noise than other system not using artificial intelligence technique and it can simplify post-processing. So, this paper is constituted hardware and software system and it used neural network for determining threshold value, when input image on pre-processing step is being stage of image binarization and present that results.