• Title/Summary/Keyword: Utility frequency

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Validation Study of Clinical Utility and Usability on Korean Version of the Life-Space Assessment to Assess Community Mobility (지역사회 이동성을 측정하는 한국어판 생활공간 평가(Korean Version of the Life-Space Assessment; K-LSA)의 임상적 유용성 및 사용성 검증 연구)

  • Kim, Jeong-Hui;Chang, Moon-Young
    • The Journal of Korean society of community based occupational therapy
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    • v.8 no.1
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    • pp.1-10
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    • 2018
  • Objective : The purpose of study is to validate the clinical utility and usability of the Korean version of the Life Space Assessment(K-LSA) which is an assessment tool of community mobility of older adults. Methods : Surveys on the clinical utility and usability of the K-LSA are carried out with a total of aoaa60 occupational and physical therapists. The surveys included the multiple choice questions on the clinical utility and open questions on the usability. Responses to multiple questions are post processed by frequency analysis and technical statistics, and responses to the open questions are categorized by common factors in each questions. Results : Average value of clinical utility ranges from 3.6 to 4.0 with positive responses of 'fair (3 point)', 'agree (4 point)' and 'strongly agree (5 point)' being 95~100%. Average value for clinical usability ranges from 3.6 to 4 with positive answers of 'fair (3 point)', 'easy (4 point)' and 'very easy (5 point)' being 88.3~100%. Additionally out of open-type questions of clinical usability, it was pointed out that the concept of 'neighborhood' for the life space level 3 and 4 is unclear. Conclusion : The current study and research outcomes showed that the K-LSA is a validated tool in Korean health care system for the clinical utility and usability in measuring community mobility, and that it is straightforward in practical use. It will help clinicians and therapists promote the social participation of older adults, and set an intervention goal for enhancing community mobility. It will further help clinicians and researchers in education and research for medical intervention and goal-setting.

A Study of New Transformerless Utility Interactive Inverter for Photovoltaic System (절연변압기를 생략한 새로운 계통연계형 햇빛발전시스템 고찰)

  • 정명웅
    • Proceedings of the KIPE Conference
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    • 2000.07a
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    • pp.670-673
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    • 2000
  • This paper describes a new inverter active inverter between a photovoltaic(PV) array and single-phase utility that avoid the bulky input(60Hz) transformer on the AC side. The interface employs a pwm boost converter on the DC side followed by a pwm boost converter on the DC side followed by a pwm current-forced single-phase rectifier for injecting the power from the PV array into the mains. The current waveform at the AC side remains sinusoidal and exactly in phase at all time. The circuit also has the advantage of requiring fewer switching device than high-frequency link system. This paper describes modeling of PV array and new system topology. Simulation results on the performance of the connection are also presented.

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A Development of a Variable Dynamic Force Type Exciter for Modal Test of a Large Structure (대형구조물 동특성 실험을 위한 가변 동하중 가진 시스템 개발)

  • Son, S.W.;Lee, H.G.;Choi, C.H.;Kang, D.E.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.11b
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    • pp.826-831
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    • 2002
  • In order to investigate the dynamic characteristics of real structure, many dynamic engineer had been interested in modal test however it is not easy to perform dynamic test of large structure because of many difficulties such as unsatisfied excitation force in global mode frequency range, measurement of dynamic force and so on. Therefore. new type vibration exciter with variable stiffness support system and dynamic force was developed to provide a improved experimental environment for a large and complex structure. The developed exciter improved from two viewpoint, dynamic performance and utility convenience. its characteristics was shown in this paper.

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Photovoltaic System for the DC Reactor Reduction of the Current Source Inverter (전류형 인버터의 리액터 경감을 위한 태양광발전시스템)

  • Park, In-Duck;Sung, Nark-Kuy;Lee, Seung-Hwan;Kang, Seung-Wook;Lee, Hoon-Goo;Han, Kyung-Hee
    • Proceedings of the KIEE Conference
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    • 1997.11a
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    • pp.484-486
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    • 1997
  • In this paper, we compose of the utility phovoltaic system with the stepdown chopper and the current source inverter to reduce pulsation of dc current and dc reactor. We study that control several ways(twice frequency of utility voltage square pulse and without the chopper) of chopper part. Therefore if voltage across the dc reactor equal to zero, it is decreased. And we control modulation factor of the chopper to operate at maximum power point around of solar cell.

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A survey on the clothing consumption activity and the home background (피복의 소비행동과 가정 배경에 관한 실태조사)

  • 남이경
    • Journal of the Korean Home Economics Association
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    • v.25 no.2
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    • pp.1-11
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    • 1987
  • The purpose of the study is to researdch clothing consumer behavior of men and women over age of 20 years and to find out the reasonable maximum utility on clothing behavior. The factors are eight distinguished parts such as sex, age, monthly income, occupation, floor space, number of room, number of family and place of residence. A common questionaire is introduced to survey the clothing consumption activity and the home background. Sources to measure them are gathered in the whole country including major cities. The questionaire of 915 correspondents of 368 males and 547 females is investigated for this research. Some of the data are analyzed by correlation, frequency, percentage, mean, and S.D. Others are investigated by ANOVA Test, x2-Test, and Multiple Range Test. The results from the survey are as followings: 1. Only four factors such as sex, monthly income, occupation, and floor space have a significance in the clothing consumption activity. 2. This survey reveals that many cloths have been kept in dead storage and concerns of utility have risen high. 3. This survey has shown that the correspondents have deep concerns about using colthing exchange store, clothing lending store, and trunk room to utilize dead storage clothing efficiently.

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A Study on the Emergency Power of the Airport with the case study (사례연구를 통한 공항의 비상전원에 관한 연구)

  • Choi, Hong-Kyu;Choi, Young-Jun
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2005.11a
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    • pp.129-133
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    • 2005
  • While everyone who uses electric power desires perfect frequency, voltage, stability, and reliability at all times, this cannot be realized in practice. The supplying utility cannot be expected to provide a perfect power supply because many of the causes of power supply disturbances are beyond the control of the utility. The outage happens but due to many reason. The electricity equipment requires consequently the emergency power supply. We classify the subordinate for quick supply of the emergency power supply and must grope the supply plan. We will find out in this paper through the case study about the emergency power efficient operation plan.

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A Novel Method for Anti-Islanding Using Reactive Power Control (무효전력 제어를 통한 새로운 독립운전 검출법)

  • Jeong Jin-Beom;Choi Bong-Ju;Ahn Kang-Soon;Kim Hee-Jun
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.54 no.4
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    • pp.208-216
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    • 2005
  • Recently, the study of islanding phenomenon, maintains its operation even when the utility grid is removed has lead to the trend of utility interactive inverters in photovoltaic generation systems. In this paper, a novel Anti-islanding method is presented. the proposed method can keep the real average power component constant by MPPT control and cause the load current frequency with only change of reactive power component under the islanding condition. its periodical change of Reactive power component can decrease the NDZ(Non-Detective zone) so that the detection of various loads will be possible. the insufficient effect if additional reactive power component to the grid is proved theoretically and the islanding detection is also confirmed from a experimental result with a inverter for 3kW photovoltaic generation system applied the proposed Anti-islanding method.

Magnetic Field Measurement and Computer Simulation for Electrical Utility Facilities (전력설비에 의한 자계 측정및 컴퓨터 시뮬레이션)

  • Jeon, Hyung-Tae;Sa, Jae-Won;Hahn, Sung-Chin
    • Proceedings of the KIEE Conference
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    • 1996.11a
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    • pp.22-24
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    • 1996
  • For two decades and more, a lot of research work on the biological effects of EMF(Electromagnetic Fields) on Human hearth have been reported. Power-frequency magnetic fields are a natural consequence of the flow of electricity. This paper deals with the modeling of electric utility facilities taking into account the line geometries. The magnetic fields profiles obtained from the computer simulation arc compared to those from measurements.

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The Effect of Consumption Value on College Students' Clothing Attitudes (남녀 대학생의 소비가치가 의복태도에 미치는 영향)

  • Park, Eun-Hee;Ku, Yang-Suk
    • Journal of Fashion Business
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    • v.12 no.5
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    • pp.141-154
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    • 2008
  • The purpose of this study was to identify factor structure of consumption value, clothing attitudes and the effects of consumption value on clothing attitudes. Questionnaires were administered to 513 college students living in Deagu and Kyungbook province. Data were analyzed by using frequency, factor analysis, multiple regression, t-test, ANOVA, and Scheffe-test. The findings are as follows. Consumption values were composed of five factors such as social value, differentiated individuality, material value, functional value, and circumstances value. Clothing attitudes were composed of five factors such as pursuit of individuality, fashion interests, utility pursuit, appearance conspicuousness, and social approval. The effects of consumption value on each of clothing attitude variables, pursuit of individuality, fashion interests, appearance conspicuousness, and social approval were explained by the factors such as social value, differentiated individuality, and functional value, utility pursuit by social value, functional value, and circumstances value.

A study on the Measurement of Power system Frequency using Digital Signal Processor (디지털 신호처리기를 이용한 전력계통 주파수 측정에 관한 연구)

  • Lee, Jung-Woo;Oh, Yong-Taek
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.25 no.2
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    • pp.113-119
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    • 2011
  • A frequency in electrical power system changes by the load fluctuation in utility grid, has an influence on a connected generator, and ultimately brings a big trouble in the power system. Therefore, a quick measurement of system frequency and governor control of power system is a very important factor in the reliability and the economic feasibility. Electromagnetic frequency relays in the past had the large power consumption and the difficulty of accurate measurement. After Researched and developed digital relays are very affected by the noise and the distortion, and the recently developed Microprocessor relays have problems of expensive device and time when measuring the frequency at 50[ms]. In this study, An improve algorithm that measures the power system frequency quickly and accurately is suggested, simulated by using Matlab and programmed using C code through DSP6713 KIT. This algorithm is tested to the arbitrary voltage waveform input. The results show that the suggested algorithm is effective in the accurate and quick frequency measurements.