• Title, Summary, Keyword: Fast self-starting

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Self-Starting Excitation System with Low-Power Permanent Magnet Generator

  • Cho, Chong Hyun;Lee, Dong-Hee
    • Journal of Electrical Engineering and Technology
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    • v.13 no.6
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    • pp.2268-2275
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    • 2018
  • This paper presents a high-efficiency low-power permanent magnet (PM) generator for the power supply of the generator exciter. In the conventional generator system, the power for the exciter is fed by the generator output power or an emergency battery for the starting. The proposed low-power PM generator can generate the proper power and voltage to excite the exciter field winding. According to the starting of the generator, the designed PM generator can supply the constant voltage to the Automatic Voltage Regulator (AVR), then it can be used to control of exciter field current for the generator. Because of the designed PM generator which is placed inside the conventional generator system, the emergency battery and Potential Transducer(PT) for AVR can be removed. Thus, the total efficiency can be improved. The proposed generator system is tested in the practical system. And the efficiency characteristic is analyzed.

Fast Consolidation Test Using Seepage Forces : Method and Validation (침투압을 이용한 급속압밀시험 : 방법 및 검증)

  • Lee, Kang-Il;Kim, Tae-Hyung;Znidarcic, Dobroslav
    • Journal of the Korean Geotechnical Society
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    • v.25 no.4
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    • pp.31-38
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    • 2009
  • A continuous, fast, and convenient experimental method, replacing recent tests such as standard oedometer or self weight consolidation test, is needed for the determination of the consolidation behavior of unformed soft soils. This study introduced the seepage induced fast consolidation test using the flow pump technique. It can obtain the consolidation characteristics of unformed soft soils conveniently and fast. The seepage induced consolidation test apparatus consists of a modified triaxial cell, differential pressure transducer, flow pump, and displacement transducer. The test continuously proceeds with starting seepage forces induced consolidation, loading consolidation, and permeability test on the same sample. In addition, this test result was compared with the standard oedometer test result to make this method valid. From this study it was found that this method is a convenient and time saving effective method for obtaining data required for calculation of consolidation settlement of unformed soft soils.

DEVELOPMENT OF THE JOINING PROCESSES IN A GLOBAL PERSPECTIVE

  • Pekari, Bertil
    • Proceedings of the KWS Conference
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    • pp.1-14
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    • 2002
  • There is a continuous development of the most common welding processes like MMA, MIG/MAG, PAW and SAW. At the same time there is a conversion from stick electrodes to solid and cored wires with an increased productivity as a result. In parallel with these changes new processes are introduced and implemented. The number of Friction Stir Welding installations is starting to grow fast Hybrid laser welding has probably made a technical break through. The Magnetic Pulse Welding process is taking off. The different mechanical joining methods; clinching and self-piercing riveting; must not be forgotten. Structural adhesive is another method to consider.

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Fuzzy Control for High Performance of Induction Motor Using Electric Vehicles (전기자동차용 유도전동기의 고성능 제어를 위한 퍼지제어)

  • 정동화
    • Journal of the Korean Society of Safety
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    • v.14 no.2
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    • pp.52-61
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    • 1999
  • This paper proposes the application of fuzzy control for high performance control of induction motor using electric vehicles. A fuzzy controller converts a set of liguistic rules based on expert knowledge into a automatic control strategy. Such controllers have often been found superior to conventional controllers especially when information being processed is inexact and uncertain. A system with fast torque response is very beneficial in applications where direct self control (DSC) is highly desirable. The response of DSC is slower during startup and during change in command torque. Fuzzy control is used for implementation of DSC to improve its slow response. Simulation implementation of the fuzzy logic controller was carried out to verify the behavior of the controller. The simulation results with fuzzy control are compared with those of the conventional DSC. The starting flux and torque response and the responses to the step changes in command torque with fuzzy implementation show a considerable improvement over the conventional control. The steady state responses in both the cases are the same.

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The Effect of Interpersonal Orientation on Consumers' Buying Motivations (대인관계성향이 구매동기에 미치는 영향)

  • Kim Kee-Ok;Yoo Hyun-Jung;Nam Su-Jung
    • Journal of Korean Home Management Association
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    • v.24 no.3
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    • pp.83-94
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    • 2006
  • In order to understand how consumers' buying motivation is formed, that is the starting point of consumer behavior or consumers' decision-making processes, we examined how the interpersonal orientation for consumers is organized to control buying motivation and create a stepping-stone for subjects' behavior in fast varied consumer environments. In addition, we examined what influence this interpersonal orientation has on consumers' buying motivations. The results are shown as follows: First, interpersonal orientation is classified into six categories, according to Cohen's three types, i.e., compliance, detachment I: emotion independence, detachment II: performance independence, detachment III: perception independence, aggressiveness I: competitiveness, aggressiveness II: aggressiveness. Second, based on our inspection of the relation between interpersonal orientation and consumers' buying motivations, for external motivation and internal motivation, the value of R2 in regression seems too low to act as an influencing power on interpersonal orientation, while in case of introjected motivation, identified motivation I: self respect, and identified II: pursuit of harmony, I there seems to be some relationship.

A Numerical Study of Smoke Movement with Radiation in Atrium Fires (아트리움에서 화재 발생시 복사가 고려된 연기거동에 대한 수치해석 연구)

  • 정진용;유홍선;홍기배
    • Fire Science and Engineering
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    • v.15 no.1
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    • pp.7-15
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    • 2001
  • This paper describes the smoke filling process of a fire field model based on a self-developed SMEP (Smoke Movement Estimating Program) codo to the simulation of fire induced flows in the atrium space (SIVANS atrium at Japan) containing smoke radiation effect. The SMEP using PISO algorithm solves conservation equations for mass, momentum, energy and species, together with those for the modified k-$\varepsilon$ turbulence model with buoyancy term. Also it solves the radiation equation using the discrete ordinates method. The result of the calculated smoke temperature containing radiation effect has shown a better prediction than the result calculated by only convection effect in comparison with the experimental data. This seems to come from the radiation effect of $H_2$O and $CO_2$ gas under smoke productions. Thus, the consideration of the radiation effect under smoke in fire should be necessary in order to get more realistic result. Also the numerical results indicated that the smoke layer is developing at a rate of about 0.1 m/s. It would take about 450 seconds after starting the ultra fast fire of 560 kW that the smoke layer move down to 1.5m above the escape level.

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Analysis and Measurement of the Magnetic Fields Cause by Operation of Electromotive Installations (전동력설비의 운전에 의해 발생되는 자계의 측정과 해석)

  • 이복희;길경석
    • The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.9 no.2
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    • pp.58-67
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    • 1995
  • The paper describes the variation of magnetic fields caused by the operation of induction motors. The measuring system consists of the self-integrating magnetic field sensor, amplifier, and active integrator. From the calibration experiments, the frequency bandwidth of the magnetic field measuring system ranges from 20[Hz] to 300[kHz] and sensitivity is 0.234(mV/$\mu\textrm{T}$]. The magnetic fields generated under steady state and starting operations of duction motor are recorded by the proposed measuring system, and the fast Fourier transformation(FFT) of the measured data is performed to analyze the harmonic components. A single pulsed magnetic field is strongly caused by direct starting the induction motor, and its peak value is greater than 5 times as compared with the steady state value. The long transient duration and high intensity originates from the large inductance and dynamic characteristic of the induction motor, During the steady state operation of induction motor, subharmonics of magnetic field components, which depend on the pole number of induction motor, are observed. The lower order power-line harmonics can be inferred from the voltage flicker and current ripple which are derived from the torque fluctuation of induction motor. In the case of the induction motor drived by inverter, the harmonics of magnetic field are much more than those caused by direct starting method and are found generally to increase with decreasing the driving frequency.

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The Study on Effects of "the Unsafe Food Program" designed For Improving Children's Eating Habits (유아들의 식습관 개선을 위한 "위험한 먹거리 프로그램"의 효과에 대한 연구)

  • Seo, Sun Suk;Lee, Ju Rhee
    • Korean Journal of Childcare and Education
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    • v.6 no.1
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    • pp.157-176
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    • 2010
  • The purpose of this study was to estimate the effect of "The unsafe food program" designed for improving children's biased eating habits coming from defenceless exposure to the instant food, fast food and adulterated food with MSG and artificial additives with analyzing the current condition of children's biased eating habits and preference for the unsafe foods. This program was performed for 5 year old children who was attending the kindergarten run by the author every day for two months. "The unsafe food program" consisted of the surveys on the parents' attitude towards food and health and children's eating habits, and of programs that was designed to attract children's attention to their daily food intake and to provide physical fitness, information about differences between wholesome food and junk food, and junk food's bad impacts on human body for children. In order to see the changes of children's body through this program, two physical examinations was preformed: SH pharmaceutical company's hair test to measure the accumulation level of toxic metal in children's hair and children's nutrition level before starting the program, and Ilsan Health Center's 'INBODY' test to analyze children's body composition such as body weight, skeletal muscle mass, body fat mass, BMI, body fat percentage and so on before and after the program. The results from this program follow as below. First, the unsafe foods were excluded from children's diet after parents came to recognize the negative effects of the unsafe foods. Second, children became highly interested in their daily diet through the course of gathering information by themselves and discussions together while testing and analyzing foods, and children demonstrated more self-restraint on fast food and instant food. Third, children's body constitution turned out to be improved by physical fitness in addition to this program. Fourth, children formed a good habit of eating well-balanced diet consisting of vegetables, staple food and fruits through this program designed to improve children's biased eating habits. From the results of this study it was confirmed that "the unsafe food project" had effects on improving children's eating habits.