• Journal of the Korean Society of Safety
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• v.33 no.1
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• pp.81-87
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• 2018

The seismic response, the natural frequencies and the mode shapes of an offshore wind turbine with twisted tripod substructure subject to various pile-ground interactions are discussed in this paper. The acceleration responses of the tower head by four historical earthquakes are presented as the seismic response, while the other loads are assumed as ambient loads. For the pile-ground interactions, the fixed, linear and nonlinear models are employed to simulate the interactions and the p-y, t-z and Q-z curves are utilized for the linear and nonlinear models. The curves are designed for stiff, medium and soft clays, and thus, the seven types of the pile-ground interactions are used to compare the seismic response, the acceleration of the tower head. The mode shapes are similar to each other for all types of pile-ground interactions. The natural frequencies, however, are almost same for the three clay types of the linear model, while the natural frequency of the fixed support model is quite different from that of the linear interaction model. The wind turbine with the fixed support model has the biggest magnitude of acceleration. In addition, the nonlinear model is more sensitive to the stiffness of clay than the linear pile-ground interaction model.

• Journal of Korean Association for Spatial Structures
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• v.21 no.4
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• pp.23-30
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• 2021

In this paper, a twisted shape structure with an elevation form favorable to the resistance of vibration caused by wind loads is selected from among the forms of high-rise buildings. The analytical model is a square, triangular, and hexagonal plane with a plane rotation angle of one degree from 0 to 3 degrees per each story. As a result of the analysis, as the twist angle increased, story drift ratio is increased. Responses with different eccentricity rates were shown by analytical models. Therefore planar shapes designed symmetrically to the horizontal axis of X and Y are considered advantageous for eccentricity and torsion deformation. In the case of the bending moment of the column, the response was amplified in the column supporting the base floor, the roof floor, the floor in which the cross-section of the vertical member changes, and the floor having the same number of nodes as the base floor. Finally, the axial force response of the column is determined to be absolutely affected by the gravity load compared to the lateral load.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.289-292
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• 2009

The line array roll set process, as one of many kinds of incremental forming processes, is a continuous process in which a flat metal plate is formed into a singly or doubly curved plate through successive passes of forming rolls. It was found that the curvature level of the formed plates in the previous study was well over the curvature required in shipyards. This fact shows that the LARS method has considerable potential for shipbuilding applications. In a shipbuilding yard, hull forming is an important fabrication process in which flat plates are deformed into singly or doubly curved plates. The major purpose of the present study is to estimate experimentally the general applicability of the line array roll set process for the manufacture of ship hull plates. In this study, the target shapes are selected through investigation of the shape classification of ship hull plates that comprise a certain vessel. Forming processes for twisted shapes are analyzed with the finite element method (FEM). Finally, the results of experimental work for two types of target shapes are presented.

• Transactions of Materials Processing
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• v.19 no.2
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• pp.120-126
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• 2010

The line array roll set(LARS) process, as one of many kinds of incremental forming processes, is a continuous process in which a flat metal plate is formed into a singly or doubly curved plate through successive passes of forming rolls. It was found that the curvature level of the formed plates in the previous study was well over the curvature required in shipyards. This fact shows that the LARS method has good potential for shipbuilding applications. The major purpose of the present study is to estimate experimentally the general applicability of the line array roll set process for the manufacture of ship hull plates. In this study, the target shapes are selected through investigation of the shape classification of ship hull plates that comprise a certain vessel. Forming processes for twisted shapes are analyzed with the finite element method(FEM) and the results of experimental work are presented. On the basis of the experimental and numerical results, the LARS process is applied to the production of real outer hull plates of a small patrol ship.

• Fashion & Textile Research Journal
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• v.7 no.1
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• pp.56-62
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• 2005

Fancy Yarn has developed diverse textures in fabrics, reducing the time in yarn and fabric production or apparel making in order to develop creative goods. In this study aimed to propose the use of a 4D box system to make fancy yarn shapes with loops, knops and spirals and the like. The change in texture was analysed and simulated to produce a suitable fabric image by using the fancy yarns fabric. The results are as follows. The plain weave, 2/2 basket weave, 2/2 twill weave, 2/2 2 complete broken weaves, and 5 harness sateen weaves were woven and a fabric image formed. In the case of the loop and the knop yarns fabric image, compared to the twisted fabric image the surface was covered by loops or some parts became partially black. In the case of the spiral shape it showed pattern continuity in spiral shapes 1, 2 and 3. The more twisted spirals produced a diamond shaped pattern or a twill line and a herring bone shaped twill line. An evenly distributed black fabric image appeared in 5 harness sateen weave. For the loop shape the broken weave or 5 harness sateen weave was produced; basket weave and broken weave for the knop yarn 1 or knop yarn 2; and for the spiral shape a plain fabric or 5 harness sateen weave were produced much similar to the fabric image. The surface texture of the mapped image compared to the twisted fabric image produces fancy yarn fabric images covered with loops or irregular spots caused by the knop and the spiral. Therefore it is appropriate or suitable for the simulation of tweed or woolen wool fabrics. The fabric image which produced consistent and continuous lines is therefore more suitable for simulations of twill or herringbone fabric images.

• 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.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.144-149
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• 2012

The transfer matrix method is used to determine the dynamic characteristics(natural frequencies and mode shapes) by rotational speed of wind turbine blade. The problems treated on this study is coupled flapwise bending and chordwise bending of pre-twisted nonuniform wind turbine blade. The orthogonality relations that exist between the vibrational modes is derived and the algorithm for determination of the natural vibrational characteristics is suggested.

• Journal of the Semiconductor & Display Technology
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• v.3 no.3
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• pp.27-29
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• 2004

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 nanotubes 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 of silicon nanotubes under torsion can be modelled in the continuum elasticity theory.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2004.05a
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• pp.63-66
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• 2004

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 nanotubes 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 of silicon nanotubes under torsion can be modelled in the continuum elasticity theory.

• 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.