• International Journal of Aeronautical and Space Sciences
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• v.8 no.1
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• pp.66-78
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• 2007

A multi-point aerodynamic shape optimization technique has been developed for helicopter rotor blades in hover based on a continuous adjoint method on unstructured meshes. The Euler flow solver and the continuous adjoint sensitivity analysis were formulated on the rotating frame of reference. The 'objective function and the sensitivity were obtained as a weighted sum of the values at each design point. The blade section contour was modified by using the Hicks-Henne shape functions. The mesh movement due to the blade geometry change was achieved by using a spring analogy. In order to handle the repeated evaluation of the design cycle efficiently, the flow and adjoint solvers were parallelized based on a domain decomposition strategy. A solution-adaptive mesh refinement technique was adopted for the accurate capturing of the wake. Applications were made to the aerodynamic shape optimization of the Caradonna-Tung rotor blades and the UH-60 rotor blades in hover.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.416-421
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• 1997

This study presents a way to construct 3D shape in STL format from 2D slice data. Nowadays ahape reconstruct has been done in many ares, the application of this method is important especially in Reverse Engineering which reconstructs original shape from cross-section data. Current RP (Rapid Prototyping) is used not only for the verification of a part designed but also for the production and tooling in more effective way. In RP technology, data should be prepared in STL format. In this paper, the way to make 3D shape data in STL format form 2D slice data is described which can be used to reconstruct an original shape in RP equipment.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.98-106
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• 1999

In this study cold rolling process for the irregular cross-sectional shape has been investigated. The product analyzed in present study is the steel cutter, which is frequently used to cut the desired shape on leather. Because steel cutter always has a irregular cross-section, after rolling process the workpiece is severely bended to every direction. The bending of the workpiece affects the processed performed after rolling such as heat treatment and grinding, then that of the workpiece becomes more severe. In this study, therefore, to prevent the bending of the workpiece to the left and right sides. rigid-plastic finite element method has been utilized and in order to find optimal roll geometry rapidly, one dimensional equal interval search technique has been also introduced. By using both rigid plastic finite element method and optimum technique, cold rolling process for the irregular cross-sectional shape has been successfully investigated.

• Journal of the Korea Concrete Institute
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• v.12 no.4
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• pp.3-14
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• 2000

Structural performance of the walls subjected to lateral load reversals depends on various parameters such as loading history, sectional shape, reinforcement, lateral confinement, aspect ratio, axial compression, etc. Thus, the performance of the shearwall for wall-type apartment should be evaluated properly considering above parameters. This study investigates the effect of sectional shape on the structural performance of the wall. Sectional shape of the specimen is rectangular, barbell and T. Based on this experimental results, all specimens behaved as ductile fashion and failed by concrete crushing of the compression zone. Deformation index of those specimens evaluated better than 3 of ductility ratio, and 1.5% of deformability specified by seismic provision. Moreover, the performance of the rectangular shaped specimen, whose compression zone was confined with U-bar and cross tie, was as good as the barbell shaped specimen. Therefore, if we considered construction practice such as workmanship and detailing, shearwall with rectangular section may be more economical lateral load resisting system.

• Journal of Ocean Engineering and Technology
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• v.15 no.2
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• pp.66-71
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• 2001

A sectional analysis of trunk-lid carried out by using the equilibrium approach based on the force balance together with geometric relations and plasticity theory. In computing a force balance equation, it is required to define a geometric curve approximating the shape of sheet metal at any step of deformation from the interaction between the die and the deformed sheet. The trunk-lid panel material is assumed to possess normal anisotropy and to obey Hill's new yield criterion. Deformation of each section of trunk-lid panel is simulated and composed to get the three-dimensional shape by using CAD technique. It was shown that the three-dimensional shape composition of the two-dimensional analysis.

• Smart Structures and Systems
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• v.24 no.2
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• pp.193-207
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• 2019

This study concerns with morphing structures, e.g. as applied in the aerospace industry. A morphing aerofoil structure capable of variable geometry was developed, which was shown to be able to cater for the different aerodynamic requirements at different stages of flight. In this work, the useful and relatively simple method has been applied, which provides a direct method for calculating required morphing shape displacements via finding the most effective bar through calculating bar sensitivity to displacement and calculating set of length actuations for bar assembly to control/adjust shape imperfection of prestressable structural assemblies including complex elements ("macro-elements", e.g., the pantographic element), involving Matrix Condensation. The technique has been verified by experiments on the physical model of an aerofoil shaped morphing pantographic structure. Overall, experimental results agree well with theoretical prediction. Furthermore, the technique of multi-iteration adjustment was presented that effective in eliminating errors that occur in the practical adjustment process itself. It has been demonstrated by the experiments on the physical model of pantographic morphing structure. Finally, the study discusses identification of the most effective bars with the objective of minimal number of actuators or minimum actuation.

• Korean Journal of Plant Taxonomy
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• v.31 no.3
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• pp.223-251
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• 2001

Morphological characters of section Atratae of the genus Carex (Cyperaceae) were reexamined. The epidermal patterns of perigynium, achene and leaf were investigated using by a scanning electron microscope (SEM) and a light microscope (LM). Morphological characters such as length and width of stem, leaf, bract, spike, scale, perigynium and achene, and shape of cross-sectioned stem, and leaf, spike, scale, apex of scale, perigynium, beak of perigynium and achene, and epidermal pattern of perigynium, achene and leaf (shape of fundamental epidermal cell and cell wall, type of silica body, shape of beak epidermal cell and cell wall in perigynium, subsidiary cell shape, size and frequency of stomatal complex of leaf) were useful for the identifications of the observed seven taxa. C. gmelinii, C. hancokiana and C. peiktusani have been confused each other due to similar morphological characters. Howerever these taxa were distinct with respect to shape of scale, apex of scale, perigynium, type of silica body, frequence of stomatal complex, subsidal cell shape, and epidermal patterns of achene and leaf.

• Journal of Environmental Science International
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• v.18 no.2
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• pp.221-230
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• 2009

In this study, a river basin with a lot of measured data such as water level, flow rate, current speed, and sediment rate from the past to now was selected and geometrical shape of a pier was re-analyzed, in order to study the effects of the flow around the pier area as well as the riverbed alternation characteristics. A finite element mesh of the entire river was prepared, and via parameter revision, the section that the pier has influence on was decided, to analyze the shape of the pier using RMA-2 and SED2D-WES models. With regards to the section that the pier has influence on, analysis was done on the four pier shapes, namely circle, square, rectangle, and octagon. The results showed that the shape with the least influence around the pier around is the octagon, followed by circle, rectangle, and square, showing the different geometrical effects that the shapes have on the pier. Furthermore, it was shown that the distribution of sediment concentration had effect from about (+) 110 m of the upstream to about (-) 130 m of the downstream, from the pier installation point. Also, it was shown after analyzing drag forces for different sediment particle distributions that the shape with the greatest drag is the octagon, followed by circle, square, and rectangle.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.9
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• pp.1106-1111
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• 2014

This paper has a purpose to find out the characteristics of pressure distribution according to the POD shape installed in the Hydrofoil vessel, using the CFD. The results showed that as we cut the POD cross-section's basic shape along the x-axis from 0 to 8cm, the viscous resistance had decreased, but then the pressure resistance had increased modestly. However, the cutoff length of POD cross-section shape has close to 9cm, the viscous drag had increased and the pressure drag had decreased. As a result, we found out that the pressure resistance made more effects in POD shape than the viscous resistance, and the total resistance decreased near the 9cm of cutoff length.

• Journal of the Korea Fashion and Costume Design Association
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• v.16 no.2
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• pp.101-109
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• 2014

Bangryeong generally means rectangular collars at present. However, it is estimated that there would be Bangryeong in different shapes besides rectangular shape in ancient times, but there is no accurate evidence. The dispute on the shape of Bangryeong started with the records in Yegi(禮記) and Simui written during Zhou period, China, the oldest records on Bangryeong. However, there are no remains or paintings(pictorial data) accurately proving the different shapes of Bangryeong. While the new shape of Gokgeop(collar of Simui) was mentioned by Zhu Xi during Song period, it was not accurately verified. There are almost no literature, excavated objects or pictorial data on the shapes of Bangryeong which are not definitely identified. The shape of Bangryeong is identified to a certain extent by objects excavated or pictorial data during Yuan and Ming period. There will be definite reasons why Zhou Xibao and Hua Mei, the scholars in China, the y-shaped collar rolled on the chest among the objects excavated during Warring States Period as Bangryeong or Guryeong. Thus, this paper investigated the notes and description in Yegijeongui(禮記正義) and the records and notes during the Han period which are mentioned most frequently except Yegi among the records on Bangryeong. Accordingly, this paper identified that there are different shapes of Bangryeong except rectangular shape during the Han period. It is estimated that Bangyeong at that time had symmetric collars, the collars of Jikryeong which are not overlapped. The collar section after the neck section was straight. It was also said that Bangyeong was women's clothing. In other words, Bangyeong in the Han period suggests that the collar of Jikryeong was Bangryeong. As discussed above, Bangryeong has the long history and different meanings by period. However, it is very difficult to accurately define Bangryeong because there are almost no records on it. Nevertheless, Bangryeong will be discussed more in further study.