• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.167-174
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• 2001

A shape resistant shell structure is an extremely efficient mechanical creation because it transmits forces mainly by in-plane forces, but at a certain load level it changes from a stable condition to an unstable condition or vise versa. The instability phenomenon of Geiger-type cable dome structure is generated due to the in-plane twisting near critical load level. Therefore the effect of bracing reinforcement is investigated for the Geiger-type model reinforced by bracing. The effect of initial imperfection is also studied since the structural instability behavior characteristic of shell-like structure is significantly sensitive according to the initial condition.

• The Journal of Korea Robotics Society
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• v.14 no.3
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• pp.221-227
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• 2019

This paper studies an effect of vibration on twisted string actuation inside conduit at high curvature angles. In our previous work. we have mentioned that twisted string actuators can be used to transmit power even at significant curvature angles of the conduit. However, several undesirable effects, namely pull-back, hysteresis, and chattering, were present during actuation due to friction between strings and the internal sheath of the conduit. This paper reports the results of experimental study on effects of vibration on twisted string actuation inside curved conduits. We have demonstrated that applying vibration generated near natural frequency of the system during the stages of twisting and untwisting cycles helped reduce pull-back and hysteresis and increase string contraction. In case when sheath was deflected by $180^{\circ}$ under a constant load of 3 kg, we were able to achieve over 40% decrease in pull-back and 30% decrease in hysteresis, compared with no vibration case.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.7
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• pp.953-959
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• 2018

This paper deals with controlling surge oscillations of a mooring vessel system under large external disturbances such as wind, waves and currents. A control synthesis based on Sliding Mode Control (SMC) with a Super-Twisting Algorithm (STA) has been applied to suppress nonlinear surge oscillations of a two-point mooring system. Despite the advantages of robustness against parameter uncertainties and disturbances for SMC, chattering is the main drawback for implementing sliding mode controllers. First-order SMC shows convergence within the desired level of accuracy, in which chattering is the main obstacle related to the destructive phenomenon. Alternatively, STA completely eliminates chattering phenomenon with high accuracy even for large disturbances. SMC based on STA is an effective tool for the motion control of a nonlinear mooring system because it avoids the chattering problems of a first-order sliding mode controller. In addition, the error trajectories of controlled mooring systems implemented by means of STA form in the bounded region. Finally, the control gain effect of STA can be observed in sliding surface and position trajectory errors.

• Journal of the Korea Safety Management & Science
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• v.23 no.3
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• pp.115-122
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• 2021

In this study, the purpose of this study was to examine the effect of twisting in the preparation of waterproofing in the process of unfolded donut-type staking method fire hoses in indoor hydrant system. The central pull-out method caused more twisting than the rolling method, and there was no significant difference in the number of twists according to the pull-out method in the case of male and female students. It was found that the time it took to untwist and prepare waterproofing was much shorter for male students. The angle valve and hose are connected, and the time to untwist and prepare for waterproofing after withdrawing the fire hose with the hose and nozzle connected was shorter than the unconnected state. In the rolling method, when a hose connected with two 15 m fire hoses was used and the angle valve-hose was connected, but the hose-nozzle was not connected, the least kinking occurred. The time to untwist and prepare for waterproofing was also the shortest. As a result, in the withdrawal method of the donut-type loaded fire hose in the indoor hydrant system, it is a rolling method rather than a central withdrawal method. With the angle valve and hose connected, unfold the fire hose with the hose and nozzle connected, if a large number of people unwind the twisted hose, the time to prepare for waterproofing can be shortened.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.5
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• pp.132-139
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• 2008

To meet demand of big capacity and high speed rotation for washing machine, more stress from bending and twisting are complexly loaded onto the shaft supporting the horizontal drum, causing problems in fracture strength and fatigue life. Also, Vibration occurs due to the frequency of the rotating parts. But, shaft has various design factors such as diameter and distance between bearings according to configuration of shaft, the optimal values can't be easily determined. Using a design of experiment (DOE) based on the FEM (Finite Element Method), which has several advantages such as less computing, high accuracy performance and usefulness, this study was performed investigating the interaction effect between the various design factor as well as the main effect of the each design factor under bending, twist and vibration and proposed optimum design using center composition method among response surface derived from regression equation of simulation-based DOE.

• Fashion & Textile Research Journal
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• v.9 no.3
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• pp.270-277
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• 2007

Buddhist temples and halls signify paradise on earth. Buddhist sutras refer to paradise as a place where flowers fall down like snow, fragrance and music fill the air, flowers blossom and butterflies fly. The Kkot Mun of Buddhist temples are an essential part of the creation of this paradise and are ornamented with elaborate sculptures of flowers and animals. The ornamentation of the Kkot Mun is truly admirable for its artistry and beauty. Although the Kkot Mun is an element of Korean traditional Buddhist architecture, it could also be applied to costume work. I thought the characteristic elements of the Kkot Mun for the costume work were the flower, the lattice and the transparent effect that was made with the lattice and Dagjongee. I used the technique of strap cutting, strap twisting and cut-out for the lattice of Kkot Mun and flower making, knitting, cut-out and quilting for the flower of Kkot Mun. I represented the transparent effect of Kkot Mun with the lapped materials. I selected six remarkable Kkot Mun of Korean temples, revised shapes of these and made six costume works. These six costume works would be the suggestion of costume design if an element of Korean traditional architecture was applied to modern costume making.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.29 no.3
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• pp.44-51
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• 2021

PIP is an abbreviation of 'Performance Improvement Package', which is a package that can improve performance by applying some design changes to existing aircraft. Boeing provides PIP applicable to B777-200, and Airbus provides PIP applicable to A350-900 as standard. PIP provided by Boeing and Airbus is a separate task, but it is expected to reduce fuel consumption by reducing drag through aerodynamic improvements. The PIP applied to the A350-900 includes work such as increasing Winglet Height and re-twisting Outboard Wing. This study is to verify the effect of PIP application of the A350-900 aircraft and use it as basic data for economic analysis. The aerodynamic improvement studies and expected effects of the PIP application were examined, and the actual flight data of the PIP-applied and the non-applied aircraft were compared to confirm the PIP application effect. This paper provides empirical results for the aviation industry on the PIP application efficiency as a method of improving fuel efficiency and reducing carbon emission.

• Korean Journal of Acupuncture
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• v.27 no.2
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• pp.203-216
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• 2010

Objectives : The purpose of this study is to identify the effect of tonifying or sedative manipulation on LI4 and KI7 for sweet deficiency under cold environment. Methods : The participants were divided into 4 groups; intact group without acupuncture(Intact), acupuncture group inserting straightly with LI4 & KI7 method((LI4-straight KI7-straight), acupuncture group inserting twisting with LI4 tonificaton & KI7 tonificaton method(LI4-tonify KI7-tonify) and acupuncture group inserting twisting with LI4 sedation & KI7 sedation method(LI4-purge KI7-purge). We obtained the baseline data under cold condition with the temperature $14{\pm}1^{\circ}C$. After making the participant staying under cold condition for 10 minute, we measured sweating rate on skin surface and biological responses such as body temperature, oxygen saturation, pulse rate, systolic blood pressure, diastolic blood pressure, deoxy-Hb and oxy-Hb in subcutaneous. Results : The sweating rate on skin surface was not different in all treatment groups compared to the intact group. The body temperature was significantly increased in LI4-straight KI7-straight group compared to the intact group. The oxygen saturation significantly increased in LI4-purge KI7-purge group compared to the intact group. The systolic blood pressure was significantly increased in LI4-purge KI7-purge group compared to the intact group. The deoxy-Hb was significantly decreased in LI4-purge KI7-purge group compared to the intact group. Conclusions : The above results, the effect of LI4, KI7 acupuncture due to the tonifying or sedative manipulation on sweating control could be observed. However, other biological responses with the acupuncture of tonifying or sedative manipulation were giving different expressions. We suggest that continued research of tonifying or sedative manipulation is of importance order to find these expressions.

• Structural Engineering and Mechanics
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• v.62 no.1
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• pp.33-42
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• 2017

We present in this paper a finite element formulation for nonlinear torsional analysis of 3D beams with arbitrary composite cross-sections. Since the proposed formulation employs a continuum mechanics based beam element with kinematics enriched by the extended St. Venant solutions, it can precisely account higher order warping effect and its 3D couplings. We propose a numerical procedure to calculate the extended St. Venant equation and the twisting center of an arbitrary composite cross-section simultaneously. The accuracy and efficiency of the proposed formulation are thoroughly investigated through representative numerical examples.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.244.1-244.1
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• 2016

Recently, the technology for flexible electronics such as flexible smart phone, foldable displays, and bendable battery is under active development. With approaching the real commercialization of flexible electronics, the electrical and mechanical reliability of flexible electronics have become significantly important because they will be used under various mechanical deformations such as bending, twisting, stretching, and so on. These mechanical deformations result in performance degradation of electronic devices due to several mechanical problems such as cracking, delamination, and fatigue. Therefore, the understanding of relationship between mechanical loading and electrical performance is one of the most critical issues in flexible electronics for expecting the lifetime of products. Here, we have investigated the effect of monotonic tensile and cyclic deformations on metal interconnect to provide a guideline for improving the reliability of flexible interconnect.