• Title/Summary/Keyword: Dynamic Measuring

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A Study on Dynamic Characteristics of EFPCD for Conductor Breaks in Low Voltage Wiring (저압배선 선로의 단선사고 발생시 전기화재예방 제어장치(EFPCD)의 동작 특성에 관한 연구)

  • 이상호;신미영;이경호
    • Fire Science and Engineering
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    • v.18 no.3
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    • pp.103-107
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    • 2004
  • Recently. the spark and the overheat due to in the conductor breaks have been the major causes of electrical fire in low voltage wiring. Also, because in these cases the current is a surge one, the losses and faults of a communication, a home appliances, a computer and a measuring instrument may occur. Especially, in such cases, we are very difficult to detect the condition of the conductor breaks. In this paper, we have developed an auxiliary control device, the electrical fire prevention control device (EFPCD), of an earth leakage breaker (ELB). And we can prevent the electrical fire caused by the spark and the overheat occurring in the conductor breaks with the EFPCD.

Analysis of Current Collect Performance Depending on Installation Condition of Overhead Contact Line in Suseo High Speed Line (수서고속철도 전차선로의 설치조건의 따른 집전상태 분석)

  • Na, Kyung-min;Park, Young;Lee, Kiwon;Cho, Yong Hyeon;Kwon, Sam-young;Park, Chulmin
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.66 no.4
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    • pp.727-732
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    • 2017
  • This paper describes the dynamic characteristics depending on installation condition between a pantograph and an OCL (Overhead Contact Line) on a new high speed line in Korea. The current collection performance between the pantograph and the OCL was tested during train operation from Suseo to Jije stations. The current collection performance is evaluated based on the duration of an arc by using an arcing measurement system. The system consists of an optical sensor for measuring the duration of an arc and a camera for monitoring current collection performance. An arcing duration is defined as a percentage of arcing in international standards. This test aims to analyze the locations of repetitive arcing depending on installation conditions of OCLs on a new high speed line in order to use the result as reference data for correct construction and maintenance.

Prestress and excitation force identification in a prestressed concrete box-girder bridge

  • Xiang, Ziru;Chan, Tommy H.T.;Thambiratnam, David P.;Nguyen, Andy
    • Computers and Concrete
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    • v.20 no.5
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    • pp.617-625
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    • 2017
  • Prestress force identification (PFI) is crucial to maintain the safety of prestressed concrete bridges. A synergic identification method has been proposed recently by the authors that can determine the prestress force (PF) and the excitation force simultaneously in prestressed concrete beams with good accuracy. In this paper, the ability of this method in the application with prestressed concrete box-girder bridges is demonstrated. A reasonable assumption is made to capture the similarity of the dynamic behavior of the prestressed concrete box-girder bridge and a beam under a certain loading scenario, and the feasibility of this method for application in a prestressed box-girder bridge is affirmed. A comprehensive laboratory test program is conducted, and the effects of PF, excitation, measuring time and uncertainties are studied. Results show that the proposed method can predict the PF and the excitation force in a prestressed concrete box-girder accurately and has a great robustness against uncertainties.

Online Strain Measurement at Multiple Points on a Rotating Blade with Fiber Bragg Grating Sensors and a Rotary Optical Coupler (광섬유 격자 센서와 회전 광학 커플러를 사용한 회전하는 블레이드 여러 지점에서의 온라인 변형률 측정)

  • Lee, Jong-Min;Hwang, Yo-Ha
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.32 no.1
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    • pp.77-82
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    • 2008
  • Strain-gauges have been dominantly used to measure strain at various points on a rotor, however, either a slip ring or telemetry has to be used to send sensor signals to data acquisition instruments at stationary side. Both slip ring and telemetry have numerous inherent problems which force severe limitations in real applications. This paper introduces a new rotor condition monitoring system using FBG(Fiber Bragg Grating) sensors and a rotary optical coupler. A single optical fiber with many FBG sensors is installed on the rotor and an optical dynamic interrogator is installed at stationary side. The sensor signal connection between rotating part and stationary part is made by the rotary optical coupling method which makes use of light's unique characteristic-light travels through space. Broad band light source from the interrogator travels to the optical fiber on the rotor and reflected FBG sensor signals travel back to the optical fiber on stationary side and are connected to the interrogator. Rotary optical coupler's insertion loss change due to rotation is compensated by using a reference sensor installed at the center of the rotor. The proposed system's performance has been successfully demonstrated by accurately measuring strains at 5 points on a blade rotating at high speed.

A study on development of Power Cable countermeasuring EFT IEC801-4 (EFT IEC801-4 대책용 전원케이블의 개발에 관한 연구)

  • 김형근;배대환;민경찬;김동일
    • Journal of the Korean Institute of Navigation
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    • v.19 no.2
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    • pp.107-113
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    • 1995
  • Since the most of the mal-functions in the industrial equipments controlled by processors have been occured by the Electrical Fast Transient(EFT), the International Electrotechnical Commision(IEC) prepare the dummy signal to test the immunity level of the equipments controlled by processors and recommend it for the measuring. In this paper, the defined dummy EFT signal by IEC are analyzed by the spectrum analyzer in the frequency domain and studied the developed countermeasuring parts. The new developed parts are consist of the feedthrough capacitors ( $C_y$ type ) in the input and materials with high permeaility which was wound or inserted in the second layer of the Power Cable in order to increase Common Mode inductance. And it is compared inserted Permalloy to material with high permeability increasing Common Mode inductance. We could gotten a excellent insertion loss on the wide band against EFT signal. Especially, we confirm that countermeasuring Power Cable have been an excellent dynamic characteristics in computer system above the 3.6Kv. This new parts could be effectively used for industrial, MIL, and medical equipments to reduce a mal-functions on the site. Furthermore, these parts also have a good characteristics for EMI countermeasuring over the 60MHz up to several GHz band, they are also expected to be used for all kind of EMS test with IEC801-2, 3, 5 and 6 on the power distributed line.

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An Experimental Study on Low-Velocity Impact Test and Response of Composite Laminates (복합적층판의 저속충격시험 및 거동에 대한 실험적 연구)

  • 최익현;홍창선
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.2
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    • pp.359-371
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    • 1994
  • A drop weight type impact test system is designed and set up to experimentally investigate impact responses of composite laminates subjected to the low-velocity impact. Using the test system, the impact velocity and the rebound velocity of the impactor as well as the impact force history are measured. An error of the measured data due to a difference in measuring position of the sensor is corrected and, for the estimation of real contact force history, a method of correcting an error due to friction forces is developed. Experimental methods to fix the boundary edgy of laminate specimens in impact testing are investigated and the impact tests on the specimens fixed by those methods are performed. Impact force histories and dynamic strains measured from the tests are compared with numerical results from the finite element analysis using the contact law. Consequently, the nonlinear numerical results considering the large deflection effects are agreed with the experimental results better than the linear ones.

A Study on Inductance compensation of Reluctance Synchronous Motor with Neural Network (신경망을 이용한 리럭턴스 동기전동기(Reluctance Synchronous Motor)의 인덕턴스 보상에 관한 연구)

  • Kim, Min-Huei;Kim, Nam-Hun;Baik, Won-Sik;Park, Hong-Il;Kim, Dong-Hee
    • Proceedings of the KIEE Conference
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    • 2002.04a
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    • pp.151-154
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    • 2002
  • This paper presents an implementation of high-dynamic performance control system of Reluctance Synchronous Motor(RSM) drives for an industrial servo drive system with direct torque control(DTC). The estimation of the stator flux and torque are obtained by using flux observer which a saturated inductance Ld and Lq of d-q axises can be compensated by using the neural network from measuring the modulus and angle of the stator current space vector. To obtain fast torque response and maximum torque/current, the reference command flux is ensured by imposing Ids=Iqs. The control strategy is proposed to fast response and optimal efficiency for RSM drive. The developed digitally high-performance control system are shown a good response characteristic of control results and high performance features using 1.0kW RSM.

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Design for Resonance Avoidance of Mount Through the Modal Analysis (모드해석을 통한 마운트 공진회피 설계)

  • Lee, Jong-Myeong;Yu, Hyeon-Tak;Park, Gyu-Jin;Choi, Hyeon-Cheol;Choi, Byeong-Keun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.25 no.7
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    • pp.481-486
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    • 2015
  • This paper provides how to solve the problems analytically and experimentally that occur for testing the water injection pump under development. First of all, water injection pump, based on shaft system dynamic analysis, is verified by measuring the behavior of the shaft system. After the water injection pump is measured, the structural resonances which can cause excessive noise, degradation the equipment life and malfunction are found. Therefore, by changing the structural design, the reso- nance should be avoided. Application of the design variables to the experimentally resonance avoid- ance is difficult. So analytically, with application of the design variables, the design will be changed with mode analysis using FEM.

Experiments for the Vibration Control of Steel Frame Structure Using Toggle Brace and Lead Rubber Damper (토글가새와 납-고무 제진장치를 적용한 구조물 진동제어 실험)

  • Park, Jung-Woo;Park, Jin-Young;Lee, Wan-Ha;Kim, Ki-Man;Park, Kun-Nok
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2011.04a
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    • pp.171-176
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    • 2011
  • The purposes of the research were to evaluate system performance and response of building structure under external load for full scale modal-testing-tower applied toggle bracing and lead rubber damper(LRD). The dynamic properties of the structure were measured before and after installing damper under harmonic excitation using the AMD and the results were compared. The harmonic excitation condition is to increase 0.01Hz sine sweep signal from 0.49Hz to 0.63Hz. As a result of measuring resonant frequency, before installing damper is 0.55Hz and after installing damper is 0.62Hz. The experimental results after installing damper were also distinguished from simulation results and the main cause of this results is temperature dependency property of rubber material.

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Stiffness Analysis of Compressed Rubber Components for Anti-Vibration (압축된 방진고무의 강성 해석)

  • Kim, Kug-Weon;Lim, Jong-Rak;Ahn, Tae-Kil
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.6
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    • pp.141-147
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    • 1999
  • Optical disk technology with a laser beam for data recording and retrieval is one of the most promising route for high density information storage in multimedia era. As the storage density and data transfer rates are increased, mechanical issues, mainly noise and vibration, become critical. Rubber materials are extensively used in various machine design application, mainly for vibration/shock/noise control devices. Over the years an enormous effort has been put into developing procedures to provide properties of rubber components with complex shape and under pre-deformed state. In this paper, non-linear large deformations of a rubber mount for optical disk drive were investigated using the finite element method. A tension test of rubber material was performed, to calculate a strain energy function. According to the pre-deformed state, the variation of rubber mount stiffness were calculated and the reliability of numerical results were checked by compared with the measuring the deflection values. Also, the effects of the pre-deformed rubber mount on the system dynamic characteristics were investigated and the relation between the static stiffness variation of rubber mount and the natural frequence variation of system was discussed.

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