• Wind and Structures
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• v.39 no.2
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• pp.101-110
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• 2024

Tall buildings are distinguished by their slenderness, making them sensitive to wind loads. A huge amount of resources is typically dedicated to controlling loads and vibrations caused by wind. Enhancing tall buildings' aerodynamic performance can save a large portion of these expenses. This enhancement can be achieved through aerodynamic optimization that can be tackled either by altering the outer shape of the building locally through modifying the corners (e.g., corner chamfering) or globally through changing the whole form of the building (e.g., twisting). In this paper, a newly developed aerodynamic optimization procedure (AOP) is adopted to enhance tall buildings' aerodynamic performance. This procedure is a combination of computational fluid dynamics (CFD), Artificial Neural Networks (ANN) and Genetic algorithm (GA). An ANN-based surrogate model is used to evaluate the aerodynamic parameters through the optimization procedure to reach a reliable aerodynamic shape. Helical twisting and corner modifications of the buildings are used to reduce the along-wind base moment.

• Transactions of Materials Processing
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• v.28 no.6
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• pp.328-335
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• 2019

Demand for ultra-thin materials is increasing due to their light-weight and versatile properties. In this work, the formability of the ultra-thin stainless steel sheets of various thicknesses in the incremental sheet forming (ISF) process is investigated. The effects of the thickness on formability were evaluated with forming experiments of the truncated cone shape with 10° intervals. As the thickness of the material decreased, the maximum forming angle decreased and wrinkles also occurred quickly. The maximum forming angles in the truncated cone shape without the wrinkles for the thickness of 0.05 mm, 0.08 mm, and 0.1mm were 30°, 40°, and 50°, respectively. Wrinkles occurred in a twisted shape along the moving direction of the tool. As the material thickness increased, the size of the wrinkles increased.

• Fashion & Textile Research Journal
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• v.8 no.2
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• pp.209-213
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• 2006

The 3-D information is useful as basic data which has been utilized in the development of simulating technology as fit-simulation. The experiment is designed to take some useful data on the variant shapes which contribute in simulating the adaptability of the clothes. The general figure of the clothes are made after the figure of the basic standing posture of the human body. The shape of the clothes fits with kinetic characteristic of the human body as the form of the clothes gets twisted, the ease of the clothes changes, and the clothes itself expands. We studied the dressed shapes of blouse according to two types of the arm movement(basic posture and reach forward) and three types of clothes(foundation, blouse with short sleeves and sleeveless) in the sit-down-posture. We accomplished some experimental data on three-dimensional measurement of the dressing shapes using TDS-3100 3-D scanner made in Japan PULSTECH. It is considered that the variant of shapes and distribution of gaps in the dressed shapes of blouse are determined by the adaptability of clothes made in arm movement.

• Journal of the Korean Society of Costume
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• v.59 no.8
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• pp.26-36
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• 2009

The aim of this study is to be the fundamental study for virtual clothing system of the future through a comparative analysis of the difference between a virtual frill skirt and a real frill skirt using a 3-dimensional Apparel cad system. Satin was selected as a comparative fabric of the real skirt and virtual skirt. And compared skirts are frilled 1.5widths, 2widths, and 2.5widths. In case of 1.5widths frilled, the real skirts and virtual skirts showed no significant difference except in shirring frill expression. However, in case of 2widths frilled, and 2.5widths frilled skirts, significant differences in the extent of frill flattening, the sectional diagram of the bottom hem, and the skirt shape. The virtual skirt showed that as its multiple proportion of frill increased, the sidelines of the skirt drooped and excessively extended, and collision detection that the belt was twisted and torn apart arose. Furthermore, not only the frill but also the shape of the skirt was transformed, and the bottom hems were widened back and forth, and the sectional diagram of the bottom hems were transformed into rounded shapes.

• Journal of Korean Association for Spatial Structures
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• v.8 no.3
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• pp.91-99
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• 2008

As number of the buildings increases, it shows new trends such as twisted, tilted, taperer shape. As a structural solution for the new trend buildings, diagonal grid (Diagrid) structure was developed. Though a few buildings was built using diagird system, the structural performance of the corresponding node was not clearly identified. Therefore, experimental evaluation is needed to apply diagrid for higher buildings. In this study, the node was tested depending on the amounts of welding materials. As a result, the partial welding can provide enough strength for the node as required in the full penetration welding under monotonin compressive loadings.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.2
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• pp.95-105
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• 2002

In order to reduce the lead-time and cost, the technology of rapid prototyping (RP) has been widely used. However, RP technologies have disadvantageous characteristics according to their working principle: low building speed, high cost for introduction and maintenance of RP apparatus, stair-stepped surface and additional post processing. A new rapid prototyping process, as a transfer type of Variable Lamination Manufacturing by using expandable polystyrene room (VLM-ST), has been developed to reduce building lime. apparatus cost including the introduction and the maintenance and additional post-processing. The objective of this study is to propose a VLM-ST process and to develop an apparatus for implementation of the process. Design criteria of the apparatus are defined and the techniques arc proposed to satisfy the design criterion. In order to examine the efficiency and applicability of the developed process, various three-dimensional shapes, such as a world-cup logo. a knob shape, an extruded cross, a twisted shape, a character, Son-o-kong. a helical gear shaped and a scissor shape are fabricated on the apparatus in which unit shape layer (USL) was generated to build up each layer.

• Journal of the Korean Society of Costume
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• v.52 no.3
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• pp.149-160
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• 2002

Symbolism found in a certain object inherits characteristics from the culture that contains the objects. The purpose of this study was investigate the formative beauty of Korean trousers twisted the pieces together based on the way of Korean thinks and the Topology. The shape is formed by cutting from the fabric. From the perspective of semiology, the fabric and the pattern shape correspond to ground and figure. Ground and figure are identical with the principle of the whole and the part, which is the same in Korea, China, and the West. But In Korea, the 3-dimensional garment is made by adding a twist. This is very important and defines the difference in the way of thinking and topology. Korean trousers consist of three parts : Hury, Marupok, and Sapok. The small Sapok can be made by removing the Marupok and large Sapok (figure) from the fabric (ground) when making Korean trousers. A Mobius strip is made when the large Sapok is adjoined with the small Sapok by reversing the small Sapok, making a 180$^{\circ}$twist and then stitching together. The theory of Mobius strip can be applied in Joining Bajiburi. thus when the trousers are completed the Klein's bottle is seen because of the 2 existing Mobius strop. The theory of Mobius strip can be applied in Joining Bajiburi, thus when the trousers are completed the Klein's bottle is seen because of the 2 existing Mobius strip. Hury is cylinder while the small and large Sapok make up the Mobius strip. As a result, Mobius strip, Kleins'bottle, protective plan can be applied in cutting Hanbok used in the countryside, so I have come to see that the traditional Korean way of thinking is closely related to the theory of topological.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.10
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• pp.670-677
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• 2011

Direct numerical simulation are performed in order to investigate the effect of the circular cylinder shape on the forced convection around a circular cylinder at the Reynolds number of 300 and Prandtl number of 0.71. Three-dimensional characteristics of fluid flow and heat transfer around the smooth, wavy and torsional cylinders are investigated. A wavy cylinder has the sinusoidal variation in the cross sectional area along the spanwise direction with the wave length of ${\pi}/3$ and wavy amplitude of 0.1. A torsional cylinder has the twisted elliptic cross section with a torsional period of ${\pi}/2$ and an axis ratio of 1.35 corresponding to the major axis of 1.15 and the minor axis of 0.85. The value of time-and surface-averaged drag coefficient for the smooth cylinder is similar to that for the wavy cylinder, but larger than that for the torsional cylinder. The time and surface-averaged lift coefficient for the smooth cylinder is larger than that for the wavy and torsional cylinders. The time-averaged local heat transfer rate for the wavy and torsional cylinders shows different distribution along the circumferential direction, compared to that for the smooth cylinder because of the shape change in the spanwise direction for the cases of the wavy and torsional cylinders.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.11
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• pp.999-1007
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• 2013

The present work reports numerical results of the pressure drop and heat transfer characteristics of pipes with various shapes such as circular, elliptical, circumferential wavy and twisted using a three-dimensional simulation. Numerical simulations are calculated for laminar to turbulent flows. The fully developed flow in pipes was modeled using steady incompressible Reynolds-averaged Navier-Stokes (RANS) equations. The friction and Colburn factor of each pipe are compared with those of a circular tube. The overall flow and heat transfer calculations are evaluated by the volume and area goodness factor. Finally, the objective of the investigation is to find a pipe shape that decreases the pressure loss and increases the heat transfer coefficient.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12S
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• pp.1165-1174
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• 2003

The responses of hypothetical silicon nanotubes under torsion have been investigated using an atomistic simulation based on the Tersoff potential. A torque, proportional to the deformation within Hooke's law, resulted in the ribbon-like flattened shapes and eventually led to a breaking of hypothetical silicon nanotubes. Each shape change of hypothetical silicon nanotubcs corresponded to an abrupt energy change and a singularity in the strain energy curve as a function of the external tangential force, torque, or twisted angle. The dynamics o silicon nanotubes under torsion can be modelled in the continuum elasticity theory.