• Title/Summary/Keyword: Wire-load System

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Suppression of Load Pendulation Using Tagline Control System for Floating Crane (해상 크레인에 의해 인양되는 중량물의 거동 감쇠를 위한 Tagline 제어 시스템)

  • Ku, Nam-Kug;Cha, Ju-Hwan;Kwon, Jung-Han;Lee, Kyu-Yuel
    • Journal of the Society of Naval Architects of Korea
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    • v.46 no.5
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    • pp.527-535
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    • 2009
  • This paper describes the control system to suppress the load pendulation using tagline for the floating crane. Dynamic equation of motion of the floating crane and the load is derived using Newton's 2nd law and free body model. The floating crane and the load are assumed that they move in center plane. Each rigid body has 3 DOF (surge, heave, pitch), because it moves in two directions and rotates. Then, this system, which is composed of two rigid bodies, has 6 DOF. The gravitational force, the hydrostatic force, the hydrodynamic force and the tension of the wire rope are considered as external forces, which affect to the floating crane. To suppress the pendulation of the load, the tagline, which connects between the load and the float crane, is applied to the system. The tagline is composed of the spring and the wire rope. Proportional and Derivative control is used as a linear control algorithm. The results of the numerical analysis of the 3,600 ton floating crane show that the tagline system is effective to suppress the load pendulation.

Calculation of Tensile Load between Roll Stands in Continuous Rolling System considering the Elasto-Plastic Behavior (탄소성 변형을 고려한 연속압연시 롤스탠드간 장력해석)

  • Shin, Nam-Do;Son, Il-Heon;Kang, Gyeong-Pil;Lee, Kyung-Hoon
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2008.10a
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    • pp.286-287
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    • 2008
  • The determination of roll speeds in continuous rolling system is an important factor along with the design of roll profile and roll gap. The tensile force on the workpiece induces reduced cross section area and the compressive force induces wrinkles. To determine the optimal roll speeds of current rough rolling system for wire rod, FE analysis was performed. We could predict the workpiece shape and the stress level more precisely by considering the elasto-plastic behavior of workpiece. Also the efficient analysis methodology is presented to reduce the calculation time by combining the ALE and lagrangian method.

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Back Fed Earth Fault Detection in Three Wire-Unigrounded Distribution-System By Zero Sequence Admittance (영상어드미턴스에 의한 직접접지 배전방식에서의 역가압 지락사고 검출)

  • Yoo, Myeong-Ho;Kim, Il-Dong;Han, Hong-Seok;Pak, Chul-Won
    • Proceedings of the KIEE Conference
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    • 1993.07a
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    • pp.120-123
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    • 1993
  • This paper presents the developing a new algorithm for detecting the Back fed Earth Fault in three wire-unigrounded distribution system by zero sequence admittance. So called "Backfed Earth Fault" of the electric power distribution line refers to a class of earth faults that the load-side line only is grounded, following after the distribution line broken into two parts, the source-side and the load-side. Because its mechanism differs from that of other earth faults, it is therefore, required to examine. This paper deals with the detailed software of the digital protective relay for Backfed earth fault. In order to prove that the proposed schemes is good, we performed off-line simulation using data from EMTP and ETSA(Electrcity Trust Of South Austrilia). It is shown that the suggested algorithm is never mal operated.

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Voltage Unbalance Factor for Phase and Line Voltage (상전압 및 선간전압에 대한 불평형율)

  • Kim, Jong-Gyeum;Park, Young-Jeen;Lee, Dong-Ju;Lee, Jong-Han;Lee, Eun-Wong;Park, Jong-Ho
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2005.05a
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    • pp.74-77
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    • 2005
  • Most of the loads in industrial power distribution systems are balanced and connected to three power systems. However, voltage unbalance is generated at the user's 3-phase 4-wire distribution systems with single & three phase. Voltage unbalance is mainly affected by load system rather than power system. Unbalanced voltage will draws a highly unbalanced current and results in the temperature rise and the low output characteristics at the machine. It is necessary to analyse correct voltage unbalance factor for reduction of side effects in the industrial sites. Voltage unbalance is usually defined by the maximum percent deviation of voltages from their average value, by the method of symmetrical components or by the expression in a more user-friendly form which requires only the three line voltage readings. If the neutral point is moved at the 3-phase 4-wire system by the unbalanced load, by the conventional analytical method, line and phase voltage unbalance leads to different results due to zero-sequence component. This paper presents a new analytical method for phase and line voltage unbalance factor in 4-wire systems. Two methods indicate exact results.

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Comparison of Voltage Unbalance Factor for Line and Phase Voltage (선간전압과 상전압에 대한 전압불평형율의 비교)

  • Kim Jong-Gyeum;Park Young-Jeen;Lee Eun-Woong
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.54 no.9
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    • pp.403-407
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    • 2005
  • Most of the loads in industrial power distribution systems are balanced and connected to three power systems. However, voltage unbalance is generated at the user's 3-phase 4-wire distribution systems with single & three phase. Voltage unbalance is mainly affected by load system rather than power system. Unbalanced voltage will draws a highly unbalanced current and results in the temperature rise and the low output characteristics at the machine. It is necessary to analyse correct voltage unbalance factor for reduction of side effects in the industrial sites. Voltage unbalance is usually defined by the maximum percent deviation of voltages from their average value, by the method of symmetric components or by the expression in a more user-friendly form which requires only the three line voltage readings. If the neutral point is moved by the unbalanced load at the 3-phase 4-wire system. Line and phase voltage unbalance leads to different results due to zero-sequence component. So that it is difficult to analyse voltage unbalance factor by the conventional analytical method, This paper presents a new analytical method for phase and line voltage unbalance factor in 4-wire systems. Two methods indicate exact results.

Theatrical Research an Generated Power of Float-Counterweight Wave Converters (부유체-균형추 파력발전장치의 전력에 대한 이론적 연구)

  • Lee, Sung-Bum;Lee, Seung-Keon;Moon, Byung-Young
    • The KSFM Journal of Fluid Machinery
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    • v.18 no.3
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    • pp.26-32
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    • 2015
  • The authors are developing a motion of floater body type wave energy converter of the float-counterweight system. This consists of the driving pulley, wire, float and counterweight suspended from idler pulleys and rachet mechanism. Though it has succeeded in solving the major structural strength problem in which the floats would slam against adjacent structure(s) by wave load acting horizontally. In order to overcome this problem. We propose a new system in which the wire transmitting the power is wound around the pulleys and the float receiving the wave power is pulled by the wire from both its upper and lower ends to avoid the occurrence of slackening during the wave cycle. In the paper, we developed the dynamics model for the proposed system. Energy gain has been calculated for realistic wave conditions and compared with the original float-counterweight device. The important differences from the float-counterweight system are that (1) both upward and downward motions of water surface can be utilized without problem. (2) slackening of energy gain and wire tension are effectively suppressed, and (4) for the same time averaged energy gain, the maximum wire tension is fairly lowered.

Mechanical Evaluation of Posterior Dynamic Omega-wire Stabilization System (후방 요추 극돌기간 유동적 오메가형 스프링 고정재의 역학적 평가)

  • Lee, Yeon-Soo;Song, Geun-Soo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.36 no.11
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    • pp.1099-1104
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    • 2012
  • The study investigates the mechanical deformation of a newly developed screwless omega-wire dynamic system for stabilization of the spine. The omega-wire spring stabilization system was tested under tension, compression, and dynamic compressive fatigue loads. In addition, its bending deformation was compared to that of a spiral-wire spring system using FEA. A model whose hanger inter-center distance is 60 mm showed an ultimate tensile stress of 3981.7 N at a displacement of 3.61 mm and an ultimate compressive load of 535.6 N at a displacement of 2.16 mm. Under fatigue loading of 5 Hz with 10 N/1 N, it did not show any failure over 5 million cycles, and the displacement was restricted to 8-9 mm. In the FEA, the omega-wire spring system showed more flexible bending features than did the spiral-wire spring system.

H-Bridge VSC with a T-Connected Transformer for a 3-Phase 4- Wire Voltage and Frequency Controller of an Isolated Asynchronous Generator

  • Kasal, Gaurav Kumar;Singh, Bhim
    • Journal of Power Electronics
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    • v.9 no.1
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    • pp.43-50
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    • 2009
  • This paper deals with a novel solid state controller (NSSC) for an isolated asynchronous generator (IAG) feeding 3-phase 4-wire loads driven by constant power prime movers, such as uncontrolled pico hydro turbines. AC capacitor banks are used to meet the reactive power requirement of the asynchronous generator. The proposed NSSC is realized using a set of IGBTs (Insulated gate bipolar junction transistors) based current controlled 2-leg voltage source converters (CC- VSC) and a DC chopper at its DC bus, which keeps the generated voltage and frequency constant in spite of changes in consumer loads. The neutral point of the load is created using aT-configuration of the transformers. The IAG system is modeled in MATLAB along with Simulink and PSB (power system block set) toolboxes. The simulated results are presented to demonstrate the capability of the isolated generating system consisting of NSSC and IAG driven by uncontrolled pico hydro turbine and feeding 3-phase 4-wire loads.

A STUDY OF THE TENSILE LOAD OF SEVERAL CLASPS ACCORDING TO VARIOUS UNDERCUT AREA (수종의 클래스프의 언더커트에 따른 인장력에 관한 연구)

  • Kim, Boong-Hwan;Lim, Ju-Hwan;Cho, In-Ho
    • The Journal of Korean Academy of Prosthodontics
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    • v.35 no.3
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    • pp.470-485
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    • 1997
  • A fundamental principle in clasp selection for a specific abutment is the reduction of the transmission of excessive forces to the abutment tooth. Those forces include tilting, tipping, and stress on the abutment tooth. The flexibility of a clasp was believed to directly affect the reduction of such forces. Opinions have been expressed concerning the proper type of clasp to be used to prevent stress on periodontium. In order to evaluate and compare the various designs of a clasp system, it is necessary to measure these forces. This study compared the average measurements of forces required to dislodge three kinds of circumferential clasps having different amount of undercuts : the first with a round retentive arm, the second with a half round retentive arm, the third with a wrought wire retentive arm under tensile load. Three commonly used undercuts( 0.01, 0.02, 0.03 inch) were created on nine cast crowns, premolars and molars. The test was run six times for a same clasp. The means of tensile load required to dislodge each of the different clasps were compared statistically using the ANOVA test and multiple range test (Duncan test). The results were as follows. 1. The amount of tensile load of the wrought wire clasp was significantly different from the cast round or half round clasp (p<0.05). 2. The more amount of the undercut, the more tensile load was needed to dislodge the clasps. There were significant differences among them (p<0.05). 3. The molar showed higher tensile load than the premolar, and there was significant difference (p<0.05). 4. The means of tensile load according to clasp types showed significant differences at the molar between wrought wire clasp and cast clasp (p<0.05), but did not at the premolar.

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Compensation of Relation Formula between Luffing Wire Tension and Overturning Moment in a Crawler Crane Considering the Deflection of Boom (크롤러 크레인에서 붐의 처짐을 고려한 러핑와이어 장력과 전도모멘트 사이의 관계식 보정)

  • Jang, Hyo-Pil;Han, Dong-Seop
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.10 no.4
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    • pp.44-49
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    • 2011
  • The crawler crane, which consists of a lattice boom, a driving system, and movable vehicle, is widely used in a construction site. It needs to be installed an overload limiter to prevent the overturning accident and the fracture of structure. This research is undertaken to provide the relation formula for designing the overload limiter as follows: First the relation formulas between the wire-rope tension and the hoisting load or the overturning ratio according to the luffing angle and length of a lattice boom are established. Secondly the derived formulas are corrected by using the compensated angle considering the deflection of boom through the finite element analysis. The stiffness analysis is carried out for 30-kinds of models as a combination of 6-kinds of luffing angle and 5-kinds of length of boom. Finally the shape design of a stick type load cell, which is the device to measure the wire-rope tension, is performed. 5-kinds of notch radius and 5-kinds of center hole radius are adopted as the design parameter for the strength analysis of the load cell.