• Title/Summary/Keyword: Movable part

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A study on the behaviour of axisymmetric outer tube and inner movable part(case) under pressure and thermal load (열하중 및 내압을 받는 축대칭 튜브와 내부 운동체의 거동해석 연구)

  • Kim, I.W.;Lee, S.B.;Park, Y.J.;Lee, Y.S.
    • Journal of the Korean Society for Precision Engineering
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    • v.10 no.1
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    • pp.114-125
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    • 1993
  • Thermoelastoplastic analysis of a typical device consisting of fixed tube and movable case having an inital clearance in between, which is subjected to pressure and thermal load, has been carried out to examine the cause of malfunction mainly at high temperature condition, and to improve the design. Stresses, deformed shape, interface state and their effects on normal function of case are discussed by using finite element method. The extraction energy can be remarkably reduced by changing the configuration of tube from the present design (Parallel type) to the improved design (Tapered type). This effect has been proved by sustained cyclic function test.

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An Optimal Design of a Driving Mechanism for Air Circuit Breaker using Taguchi Design of Experiments (다구찌실험계획법을 활용한 기중차단기의 메커니즘 최적화)

  • Park, Woo-Jin;Park, Yong-ik;Ahn, Kil-Young;Cho, Hae-Yong
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.21 no.9
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    • pp.78-84
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    • 2022
  • An air circuit breaker (ACB) is an electrical protection device that interrupts abnormal fault currents that result from overloads or short circuits in a low-voltage power distribution line. The ACB consists of a main circuit part for current flow, mechanism part for the opening and closing operation of movable conductors, and arc-extinguishing part for arc extinction during the breaking operation. The driving mechanism of the ACB is a spring energy charging type. The faster the contact opening speed of the movable conductors during the opening process, the better the breaking performance. However, there is a disadvantage that the durability of mechanism decreases in inverse proportion to the use of a spring capable of accumulating high energy to configure the breaking speed faster. Therefore, to simultaneously satisfy the breaking performance and mechanical endurance of the ACB, its driving mechanism must be optimized. In this study, a dynamic model of the ACB was developed using the MDO(Mechanism Dynamics Option) module of CREO, which is widely used in multibody dynamics analysis. To improve the opening velocity, the Taguchi design method was applied to optimize the design parameters of an ACB with many linkages. In addition, to evaluate the improvement in the operating characteristics, the simulation and experimental results were compared with the MDO model and improved prototype sample, respectively.

A Secular Change of Strength for Galvanized Steel Pipes for Vinyl Housing (비닐하우스용 아연도강관의 강도경년변화 시험(농업시설))

  • 남상운;김문기;권혁진
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 2000.10a
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    • pp.296-301
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    • 2000
  • Bend test for metallic materials was conducted on samples of galvanized steel pipes being used in greenhouse farms. A secular change of yield strength for galvanized steel pipes was analyzed with the part of buried in the ground and exposed in the atmosphere. From those experimental results and corrosion rate of galvanized film, the standard durable years for pipe framed greenhouses are estimated that the small sized pipe houses of movable type is 7∼8 years and the large sized pipe houses of fixed type is 14∼15 years.

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An Analysis of Starting Motions in Time 300m Inline Skating (인라인 스케이트 T300m 출발동작 분석)

  • Park, Ki-Beom;Yang, Jeong-Ok;Lee, Joong-Sook
    • Korean Journal of Applied Biomechanics
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    • v.13 no.2
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    • pp.123-137
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    • 2003
  • This study is to present more effective starting skills through analysis of kinematic characteristics of starting motions in 300m Time Trials of Inline Skating. To achieve this goal, 6 athletes, 3 in the national team and 3 in business teams were chosen and their starting motions were examined with three-dimensional image analyses. The results of analyses in regard of positions and speed of the bodily center and angles, angular velocity, and linear velocity of articulations of lower limbs by sections of starting motions are as follows: In case of the central position, though it is effective to reduce the air resistance by lowering the upper part of the body maximumly, it is reasonable to accelerate by raising the upper part of the body to some degree for the running posture at the lower speed in the starting section. In the starting section, it is efficient to minimize the period of time in touching the ground. for this, it is necessary to train for taking motions without slippage while touching the ground. While 3 athletes in business teams kicked the ground as running right after the starting, the others in the national team slid on the ground. As the number of steps increased, the movable speed changed quickly. Thus the movable speed of athletes in the national team indicated big differences in two to three steps. If these factors are well supported, the push-away starting method might be better than the running starting method in terms of improvement of records.

Limitations for the control of wind-loaded slender bridges with movable flaps

  • Kirch, Arno;Peil, Udo
    • Wind and Structures
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    • v.15 no.5
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    • pp.441-462
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    • 2012
  • This article presents theoretical investigations on techniques for the improvement of the dynamic characteristics of slender bridges under wind action. Aerodynamically effective control shields are applied as controlled actuators. The first part of the article describes the modelling of the uncontrolled aeroelastic system. Acting aerodynamic forces are consistently characterised using linear time-invariant transfer elements in terms of rational functions. On this basis, two configuration levels of the uncontrolled system are represented with linear time-invariant state-space models and investigated. The second part of the article addresses controller design and the behaviour of the controlled aeroelastic system. Both fundamental limits for stabilisation and the efficiency for attenuating the influence of gusts are described for different actuator mechanisms. The results are derived and discussed with methods of control theory.

Influence of twisting angle between fixed contact and movable contact on arc driving force in 3petal spiral type vacuum interrupter (3petal spiral type vacuum interrupter에서 가동접점전극과 고정접점전극간의 마주보는 각도의 변화가 아크구동력에 미치는 영향)

  • Kim, Byoung-Chul;Yun, Jae-Hun;Lee, Seung-Soo;Kang, Seong-Hwa;Lim, Kee-Joe
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.06a
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    • pp.480-480
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    • 2008
  • Vacuum circuit breaker(VCB) is now emerging as an alternative of gas circuit breaker(GCB) which uses SF6 gas as insulating material whose dielectric strength is outstanding. But we have to reduce SF6 gas because SF6 gas is one of greenhouse gas and efforts to reduce greenhouse gas are now trend of the world. Therefore, we can say VCB is the optimal alternative of GCB because vacuum is environmentally friendly. The vacuum interrupter is the core part of VCB to interrupt arcing current. There are mainly two methods to extinguish arc. One is radial magnetic field (RMF) method and the other is axial magnetic field (AMF) method. We deals with RMF method in this paper. Compared with AMP, RMF arc quenching method has different principle to extinguish arc. In case of RMF method, pinch effect is much larger than AMF method. Because of pinch effect RMF type contact electrodes have the single large spot which is severly damaged and melted while AMF type contact electrodes have small and multiple spots which are slightly damaged and melted. To prevent contact electrode being damaged and melted from high temperature-arc, RMF method uses Lorentz force to move arc. In this paper we calculated and compared the arc driving force of two cases and we analyzed the force acting on each part of arc by means of commercial finite element method software Maxwell 3D. They have 3petals and we considered two cases. One is the case when fixed(upper) and movable(lower) contacts are in mirror arrangement (Case 1). The other is the case when one of two contacts (movable contact) is revolved at maximum angle as possible as it can be (Case 2). And at each case above, we analyzed arc driving force at two positions, position 1 is the closest to the center of contact and position 2 is near the edge of petal on fixed contact. As a result we could find that Case 2 generated stronger arc driving force than Case 1 at position 1. But at position 2 Case 1 generated stronger arc driving force than Case 2. This simulation method can contribute to optimizing spiral-type electrode designs in a view of arc driving force.

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A study on improvement of regular survey system of state-designated movable cultural heritage (국가지정 동산문화재의 정기조사제도 개선방안 연구)

  • Lee, Jong-Suk;Kim, Chang-Gyoo
    • Korean Journal of Heritage: History & Science
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    • v.51 no.4
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    • pp.146-169
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    • 2018
  • Artificial or natural artifacts, which have historical, artistic, academic or scenic value as national, ethnic or global assets, are designated as "cultural heritages" under the Act on the Protection of Cultural Heritage. Cultural heritages can be divided into tangible cultural heritages, intangible cultural heritages, and monument and folklore heritages. In addition, depending on the object of designation, a cultural heritage can be designated either as a city or a provincial cultural heritage or a cultural heritage material, by a city mayor or provincial governor, and as a state-designated heritage by the administrator of the Cultural heritage Administration. The regular survey is a part of the policy for the preservation and management of state-designated heritages, which requires that surveys be undertaken every three to five years for the preservation, repair and maintenance of cultural heritages. It was stipulated in the Act on the Protection of Cultural Heritage in 2006, and since then has substantially contributed to the preservation and management of state-designated heritages based on the identification of damage to cultural heritages and the application of appropriate treatment measures. However, some parts of the guidelines on the regular survey, legislated in 2006, occasionally give rise to confusion in managing the regular survey system of state-designated movable cultural heritages, and need to be modified to facilitate the systematic management and improvement of the regular survey system. This study attempts to analyze the structure and operation of the regular survey system of state-designated movable cultural heritages, and proposes plans for improving the way of specifying each department which leads, manages and executes the regular survey, the process of entrusting the survey, and its guidelines and forms. I hope that these plans concerning the regular survey of state-designated movable cultural heritages will contribute to improving the quality and management of the system.

A Study on Reconstruction Models of Side-channel Spillway for Discharge Capacity Improvement (측수로형 여수로의 홍수배제능력증대를 위한 월류부 개축방안에 관한 연구)

  • Park, Sae-Hoon;Moon, Young-Il
    • Journal of the Korean Society of Hazard Mitigation
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    • v.7 no.3
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    • pp.9-18
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    • 2007
  • The small and medium sized dams have the fill dam type of a lot of occasions, which are often weak in cases of major floods. For this reason, although a countermeasure is in great need, due to the importance of the facilities and financial situations, no direct safety measures have been taken. In this study, in order to minimize construction expenditure for practical safety measures in cases of major floods, the overflow section of spillway has been analyzed focusing on how the overflow capacity will increase in the case of partially rebuilding a part of the overflow section of spillway favorable for hydraulic conditions. The labyrinth weir and movable weir was chosen for reconstruction models of the overflow section. Moreover, for analyzing the after-effects of the reconstruction, a small scale dam was temporarily chosen for various experiments such as the hydraulic model testing and the three dimension numerical evaluation through the use of Flow-3D.

Equivalent Impedance Modelling and Frequency Characteristic Analysis of Linear Oscillatory Actuator System Considering Mass/spring System (질량/스프링 계를 고려한 리니어 왕복 액추에이터 시스템의 등가 임피던스 모델링과 주파수 특성 해석)

  • Jeong, Sang-Seop;Jang, Seok-Myeong
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.51 no.7
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    • pp.370-378
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    • 2002
  • As resent trends in structural construction have been to build taller and larger structures than any time in the past, they have had high flexibility and low damping that can cause large vibration response under severe environmental loading such as earthquakes, winds, and mechanical excitations. The damper with mass and spring is one approach to safeguarding the structure against excessive vibrations. In this paper, the lumped electrical circuit approach of mass/spring system is used to model the mechanical aspects according to the frequency. Therefore, the mass/spring system can be dealt with here and linked with the equivalent circuit of electric linear oscillatory actuator(LOA). Analysis models are two types of vibration control system, active mass damper(AMD) and hybrid mass damper(HMD). AMD consists of the moving coil LOA with mass only The LOA of HMD with mass and spring is composed of the fixed coil and the movable permanent magnet(PM) field part. The PM field part composed magnet modules and iron coke, is the damper marts itself. We Present the motional resistance and reactance of mass/spring system and the system impedance of AMD and HMD according to the frequency.

A Study on the Application of U-SAT System for the Indoor Positioning Technology of Ubiquitous Computing (유비쿼터스 컴퓨팅의 실내 측위 기술을 위한 U-SAT 시스템의 적용에 관한 연구)

  • Lee, Dong-Hwal;Park, Jong-Jin;Kim, Su-Yong;Mun, Young-Song;Lee, Man-Hyung
    • Journal of Institute of Control, Robotics and Systems
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    • v.12 no.9
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    • pp.876-882
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    • 2006
  • This study presents an ultrasonic location awareness system for the ubiquitous computing with absolute position. The flight time of ultrasonic waves is determined by a period detecting technique which is able to extend the sensing range compared with traditional methods. For location awareness, ultrasonic waves are sent successively from each ultrasonic transmitter and synchronized by radio frequency (RF) signal, where the transmitting part is fixed and the receiving part is movable. To expand the recognizing range, cell matching technique and coded ultrasonic technique are introduced. The experimentation for various distances is accomplished to verify the used period detecting technique of U-SAT system. The positioning accuracy by using cell matching is also verified by finding the locations of settled points and the usability of coded ultrasonic technique is verified. As a result, the possibility of ultrasonic location awareness system for the ubiquitous computing can be discussed as a pseudo-satellite system with low cost, a high update rate, and relatively high precision, in the places where CPS is not available.