• Journal of the Computational Structural Engineering Institute of Korea
• /
• 제26권1호
• /
• pp.89-97
• /
• 2013

With regard to complex-shaped tall buildings whose plans and constructions have been gradually on the increase, this study was aimed to analyze their structural behaviors during construction by applications of construction sequences analyses to prototype models. For twisted tall buildings, total 18 models of with three conditions of a lateral load-resisting system, a twisting angle, and a construction method were selected. A diagrid system and a braced tube system were applied as a lateral load-resisting system. For each lateral load-resisting system, three types of plan with $0^{\circ}$, $1^{\circ}$, and $2^{\circ}$ twisting angles and three construction methods with construction sequences of exterior tube and interior frame were assumed. The structural performances of tall buildings under constructions were analyzed with results of lateral displacements from construction sequence analyses. Also, construction performances of the construction period and the maximum lift weight were compared.

• Journal of the Korean Society of Costume
• /
• 제59권8호
• /
• pp.26-36
• /
• 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.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 한국정밀공학회 1994년도 추계학술대회 논문집
• /
• pp.169-175
• /
• 1994

This study attempts to develop a process which can produce three-dimensional shapes of metals directly from CAD data. Prototypes made from metals, can not only be used to test the mecchanical properties of the product, but also potentially become the actual die or product itself. The test-device of the process has been designed and manufactured. The laser scanning method using a scanning path schedule composed of circle and arc elements, scanning speed variation method and dwell method have been developed, which resist warping phenomenon and increase the adhesiveness between the layers. For the production of prototypes with pure iron powder, the optimal values of the principal process parameters have been determined, through which cross-shaped and twisted clover-shaped prototypes have been fabricated. In order to improve the strength of the prototype, the experimental studies of solid-phase sintering, and copper infiltration have been done.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• 제16권12S호
• /
• pp.1165-1174
• /
• 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.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• 제13권10호
• /
• pp.939-946
• /
• 2001

This study investigates the electrical and collection characteristics of a wide plate spacing electrostatic precipitator (ESP), using a pilot-scale one. Electrical operating characteristics and collection efficiency were measured for various shapes of discharge electrodes. The collection plate spacing ranged from 300 to 550 mm. Results of electrical characteristic and collection efficiency tests as a function of collection plate spacing, discharge electrode type, applied voltage, and particle diameter were obtained. Increasing the collection plate pitch and altering the corona electrode geometry was found to increase the collection efficiencies without increasing input power requirement. The best efficiency is achieved for the discharge electrode of twisted pin type.

• Journal of KSNVE
• /
• 제5권2호
• /
• pp.215-224
• /
• 1995

In this paper, the three-dimensional finite element model is established to investigate the structural dynamic characteristics of rotor blade using a finite element analysis. Six natural frequencies and mode shapes are calculated by computer simulation. The first three flapping modal frequencies, the first two lead-lag modal frequencies, and the first feathering modal frequency are validated through comparison with the modal test results of the fixed rotor blade. The computer simulation results are found in good agreement with experimentally measured natural frequencies. The important results are obtained as follows: (1) Natural frequencies are changed due to the variation of rotational speed and fiber angle of rotor blade, (2) Weak coupling between flapping mode shape and lead-lag mode shape are detected, (3) Centrifugal force has more effect on flapping modal frequency than lead-lag modal frequency.

• Progress in Superconductivity and Cryogenics
• /
• 제25권4호
• /
• pp.40-44
• /
• 2023

For high-temperature superconducting power applications that need large current capacity, a large current conductor manufactured using multiple superconducting tape is required. Conductors being studied for large currents capacity such as CORC, TSTC, and RACC have advantages and disadvantages, and in order to use these conductors in coil form and apply them to AC power devices, research on magnetization loss occurring in superconductors due to external magnetic fields is essential. To accurately measure magnetization loss in a conductor that is twisted by stacking straight conductors like TSTC, the correlation between the measuring system and the shape of the sample must be clearly known to accurately measure the loss. In this paper, we will confirm the difference in magnetization loss measurement values according to the correlation between the length of the pickup coil and the twist pitch of the sample in CORC and TSTC shapes, and review considerations for accurate magnetization loss measurement from the results.

• IE interfaces
• /
• 제21권4호
• /
• pp.411-417
• /
• 2008

An impeller is a type of high-speed rotor that is used to compress or transfer fluid under high-speed and pressure at high temperatures. The impeller is composed of an axial hub and several blades attached along the hub. The weight and shape of an impeller must be balanced, because their imbalances can cause noise and vibration, which can lead to the breakage of the impeller blades during operation. Thus, the hub and blades of an impeller are commonly machined in a 5-axis NC machine to obtain qualified surfaces. The impeller machining strategy or process plan can not be easily obtained due to the complex, overlapped and twisted shapes of impeller blades. Skillful machining process planners may generate appropriate machining strategies based on their experiences and floor data. However, in practice most shop floor data for the impeller machining is not well-structured such that it does not effectively provide a process planner with information for machining strategies and/or process plans. This paper reports the development of a case-based machining strategy support system (CBMS) that employs case-based reasoning to obtain the machining strategy of an impeller by using the existing machining strategies of the shop floor. The CBMS generates impeller machining strategies through a stepwise reasoning process considering the similarity features between the blade shapes and machining regions. A case study is provided to demonstrate that CBMS can generate useful machining strategies facilitating process planners. The developed system can simulate the tool paths of impeller machining and runs on the web.

• Journal of Korean Society for Quality Management
• /
• 제44권4호
• /
• pp.935-949
• /
• 2016

Purpose: This study attempts to find out the optimum condition of the rotary cutter making pellet in the footwear outsole process. The pellets are used in the process of outsole rubber fabrication to reduce cycle time and save raw material. Methods: Computer simulations are used to analyze the maximum stress in the rotary cutter after designing a variety of cutter shapes. Taguchi method is used to identify the robust condition of the cutter. In $L_{18}$ orthogonal array, the control factors such as knife width, twisted angle, number of knives, diameter, knife depth and supported angle are considered and noise factors like assembly tolerance and amount of antifriction are allocated. Results: It is found that the most important factors to reduce maximum stress in the cutter are supported angle and diameter. Using Tacuchi's results, we can reduce 70% cycle time and 9% raw material compared to the traditional method using cutting die. Conclusion: When designing the rotary cutter, the best conditions are the diameter at its maximum allowable value and supported angle in the boundary of machine inner space.

• International Journal of High-Rise Buildings
• /
• 제2권3호
• /
• pp.229-244
• /
• 2013

Twenty six pressure models of high rise buildings with various cross-sections including twisted models were tested in a boundary layer wind tunnel. The cross-sections were triangular, square, pentagon, hexagon, octagon, dodecagon, circular, and clover. This study investigates variations in peak pressures, and effects of various cross-sections and twist angles on peak pressures. To study the effects of various configurations and twist angles on peak pressures in detail, maximum positive and minimum negative peak pressures at each measurement point of the building for all wind directions are presented and discussed. The results show that peak pressures greatly depend on building cross-section and twist angle.