• Journal of Power Electronics
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• 제16권2호
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• pp.675-684
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• 2016

This paper presents a new stand-alone wind-based induction generator system with constant frequency and adjustable output voltage. The proposed generator consists of a six-phase cage-rotor induction machine with two separate three-phase balanced stator windings and a three-phase space vector pulse width modulation inverter that operates as a static synchronous compensator (STATCOM). The first stator winding is fed by the STATCOM and used to excite the machine while the second stator winding is connected to the generator external load. The main frequency of the STATCOM is determined to be constant and equal to the load-requested frequency. The generator output frequency is independent of the load power demand and its prime mover speed because the frequency of the induced emf in the second stator winding is the same as this constant frequency. A sliding mode control (SMC) is developed to regulate the generator output voltage. A second SMC is used to force the zero active power exchanged between the machine and the STATCOM. Some simulation and experimental results are presented to prove the validity and effectiveness of the proposed generator system.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권8호
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• pp.425-433
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• 2002

This research investigates the electromechanical characteristics of a sing1e-phase squirrel cage induction motor due to broken rotor bars and rotor eccentricity. Numerical analysis is performed by solving the nonlinear time-stepping finite element equation coupled with the magnetic field equation, circuit equation and mechanical equation of motion. It shows that the asymmetry of magnetic flux due to the broken rotor bars and rotor eccentricity introduce a change in the stator current, torque, speed, magnetic force and vibration of a rotor at the same time. However, even in the existence of rotor eccentricity, 3 broken rotor bar introduces a dominant change in the magnetic force and rotor displacement, i.e., beating phenomenon in time domain and sideband frequencies in frequency spectra, respectively.

• 조명전기설비학회논문지
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• 제29권7호
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• pp.38-46
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• 2015

This paper propose a variable parameter estimations for variable over current load of five-phase squirrel-cage induction motor(IM) to servo control system. In order to high performance control of AC motor using a field oriented control(FOC) and direct torque control(DTC) algorithm, there are required precise motor parameters for slip calculation, flux observer, controller gain, torque command of current components, rotor position, speed estimation, and so on. We are suggest a analyzed estimation results of the motor parameters that developing five-phase squirrel-cage IM have a stator of concentrated winding for experimental within variable over current load at rated input frequency. There are results of stator winding measurement, no-load test, locked-rotor test, variable over current load test, and estimated parameters of equivalent circuits using manufactured experimental apparatus by IEEE Standard Test Procedure for Polyphase Induction Motors and Generators 112-2004.

• 농촌의학ㆍ지역보건
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• 제29권1호
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• pp.147-161
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• 2004

본 연구 지역에서의 연구대상자 중 AUDIT 12세 이상, CAGE 2점 이상을 기준으로 한 문제음주자의 비율이 각각 28.3%, 30.0%로 다른 전국 단위 조사결과에 비해 높았다. 본 연구에서 사용한 문제 음주의 선별도구로써의 CAGE, AUDIT는 그 점수가 높은 사람이 술을 자주 마시고, 1회 음주량도 많으며 주간 알코올 섭취량도 많은 유의한 상관관계를 나타내었고, CAGE, AUDIT를 기준으로 문제음주를 분류하였을 때 문제음주가 아닌 집단과 음주 현황 및 음주 인식도와 음주로 인한 폐해에 있어서 전반적으로 유의한 차이를 보였다. 그러므로 CAGE와 AUDIT가 농촌지역사회의 문제음주에 대한 선별과 음주관련 현황 조사도구로써 유용하다 하겠다. 본 연구는 농촌지역사회 인구를 대상으로 한 CAGE, AUDIT의 타당도 검증을 목적으로 한 연구는 아니었지만, 지금까지 한글로 번역된 문제성 음주의 선별도구들의 타당도 조사가 병원에 방문한 환자를 중심으로 이루어졌다는 점을 감안하면, 이후 연구에서 지역사회에서의 CAGE, AUDIT의 타당도 조사가 이루어질 필요가 있겠다. 음주에 대한 인식에 있어 문제음주 집단이 문제음주가 아닌 집단보다 대체로 적정 음주량이나 음주문화에 관대한 편으로 나타나 농촌지역의 문제음주자의 상당수는 문제음주를 인식하지 못하고 습관적으로 음주를 하고 있음을 알 수 있었다. 여가 활동에 있어서 문제 음주자와 문제음주가 아닌 집단 간에 유의한 차이는 없었으나, 농촌사회 여가활동의 대부분이 혼자 TV보거나 아니면 마을회관 등에서 이웃과 모여서 놀면서 습관적 음주가 일어나는 단순한 형태로 이루어지고 있어 적절한 여가활용을 통한 절주프로그램 개발이 필요하다고 여겨진다. 본 연구는 농촌지역의 지역사회 내 음주현황과 문제음주를 일으키는 음주행태와 음주문화, 여가 활용 등의 여러 관련요인에 대한 이해를 할 수 있게 할 것이다. 농촌지역에서 건강한 음주문화를 정착시키고 문제음주율을 낮추기 위해서는, 문제음주와 습관성 음주에 대한 올바른 인식을 확대시키고, 음주를 대체할 수 있는 건강한 여가시간 활용을 위해 지역사회 기반시설과 프로그램 마련 등의 노력을 계획해 볼 수 있을 것이다. 이렇게 함으로써 농촌 지역에서의 절주 프로그램이 실효를 거둘 것으로 생각되며 이를 통해 농촌인구의 건강증진에 기여할 수 있을 것으로 기대된다.

• Asian-Australasian Journal of Animal Sciences
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• 제23권4호
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• pp.537-542
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• 2010

The goal of this study was to investigate how spectrographic features of ultrasonic vocalizations (USVs) in rats vary among individuals and behaviors. Eighteen pairs of rats were allocated to individual pair cages. Each pair's behaviors and vocalizations were recorded during the 900s a known cage-mate was returning to the cage. The effects of individuals, behaviors, and the interaction between individuals and behaviors ($individuals{\times}behaviors$) were tested on the duration and peak frequencies. There was difference in the duration and peak frequency: i) among individuals (p<0.0001 and p<0.0001, respectively); ii) among behaviors (p = 0.0667 and p<0.0001, respectively); iii) among individuals${\times}$behaviors (p<0.0001 and p<0.0001, respectively). The frequency of ultrasonic vocalizations changed with a frequency ranging from 40 to 71 kHz which were emitted by individuals, whereas the frequency of ultrasonic vocalizations changed with a frequency ranging from 60 to 70 kHz which were emitted by behaviors. The peak frequency of call on 'contact' behavior was lower than that of call on other behaviors, but call duration of call on 'contact' was longer than on other behaviors. Especially, 40 kHz calls were found on 'contact' and 'other' behaviors. We suggest that ultrasonic vocalizations need to be subdivided and the effects of individuals and behaviors must be considered to assess emotional state of rats because these may influence the features of ultrasonic vocalizations.

• Journal of Animal Science and Technology
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• 제51권5호
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• pp.421-426
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• 2009

본 연구는 산란계의 사육공간의 크기별 발성음의 특성을 파악하기 위해 하이라인브라운(Hy-Line Brown) 80주령의 산란계를 대상으로 2008년 10월부터 2009년 2월까지의 기간 동안 발성음을 수집 및 녹음하였다. 산란계의 사육 케이지는 무항생제 축산물 사육밀도조건을 만족하는 0.0231 $m^3$ (0.3m ${\times}$ 0.14m ${\times}$ 0.55m)을 개체당 사육공간의 기준(control)으로 하고, 좁은 공간(small, 0.21m ${\times}$ 0.14m ${\times}$ 0.55m)과 넓은 공간(large, 0.3m ${\times}$ 0.3m ${\times}$ 0.55m) 등의 3가지 유형으로 구분하였다. 하루 3회, 각각 1시간씩 디지털 녹음기(PMD-650, Marantz)와 마이크(MKH 416P48, RF Condenser Mic.)를 이용하여 발성음을 녹음하여 분석을 실시하였다. 발성음의 스펙트로그램을 비교한 결과 케이지의 크기별로 차이가 있는 것으로 나타났으며, 스펙트럼을 비교한 결과 역시 차이가 있었다. 또한 발성음의 주파수, 강도 및 길이 역시 통계적으로 유의한 차이를 나타내었다. 본 연구를 통해 산란계의 사육공간과 발성음 사이에는 깊은 관련이 있었으며, 사육공간에 의한 스트레스의 정도를 파악하기 위해 발성음은 매우 유용할 것으로 판단된다.

• Composites Research
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• 제14권3호
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• pp.77-89
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• 2001

초고속 일체형 주축의 공진주파수가 일체형 주축 시스템의 모터 회전자의 질량과 주축의 굽힘 강성에 의존하기 때문에 초고속 주축 시스템의 동적 특성을 향상시키기 위해 주축과 회전자를 각각 고분자 기지 섬유강화 복합재료와 자성분말이 함침된 에폭시 수지를 이용하여 설계하였다. 설계된 복합재료 회전자의 자기 특성을 향상시키기 위해 내부에 강철 코어를 삽입하였으며, 강철 코어와 전도체 봉의 기하학적 형상의 변화가 전동기의 성능에 미치는 효과를 파악하기 위해 자기 해석을 수행하였다. 유한요소해석을 통해 복합재료 회전자의 최적의 기하학적 조건을 제안하였다. 또한 복합 재료 회전자 재료의 열특성을 파악하기 위해 TMA, DMA및 VSM을 이용한 기계적, 전자기적 물성측정을 수행하여 복합재료 회전자의 최적 설계에 적용하였다.

• 대한가정학회지
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• 제43권3호
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• pp.27-43
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• 2005

The purpose of this study was to determine the drinking behaviors and drinking problems of adult, mentally retarded persons over 18 years old. It was also investigated whether gender, age, and pattern of employment create different result of drinking behaviors and drinking problems, and the variables explaining drinking problems were analyzed. One hundred forty adults, mentally retarded persons were surveyed in Seoul and KyeongGi area. The major findings were as follows; The majority of respondents ($58.2\%$) reported that they had consumed alcohol beverages sometimes prior to their having been interviewed. The average age of respondents who had consumed alcohol was 26.4 years and average age of first-use of alcohol was 22 years. For consumption frequency, $39.2\%$ of respondents reported that they drink alcohol once a month. Average alcohol consumption per occasion was 1.5 cups, and $10.9\%$ of respondents answered more than 5 cups per occasion. Regarding problems associated with drinking, $16\%$ of respondent of AUDIT and $51.4\%$ of Family CAGE answered that their children have drinking-related problems. Men drink more than women and experience more alcohol problems. Supervised employment group was the group with the greatest prevalence for drinking. For the amount of drinking, gender and employment pattern showed significant differences. Drinking problems (AUDIT and Family CAGE) of adult, mentally retarded persons were influenced by age of first-use of alcohol, frequency of alcohol use, and alcohol consumption.

• Bulletin of the Korean Chemical Society
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• 제32권1호
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• pp.277-280
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• 2011

We studied the relative stability and atomic structure of five $C_{20}^{2+}$ isomers obtained by two-electron ionization of a $C_{20}$ cage (the smallest fullerene). All the isomers are bond-stretch isomers, i.e., they differ in bond length. In particular, in one of the isomers with Ih symmetry, all the bond lengths are equal. Full geometry optimizations of the dipositive ion $C_{20}^{2+}$ were performed using the hybrid density functional (B3LYP/6-31G(d)) methods. All isomers were found to be true minima by frequency analysis at the level of B3LYP/6-31G(d) under the reinforced tight convergence criterion and a pruned (99,590) grid. The zero-point correction energy for the cage bond-stretch isomers was in the increasing order $D_{2h}<C_{2h}<C_2<T_h<I_h$ of $C_{20}^{2+}$. The energy difference among the isomers of cage dipositive ions was less than that among neutral cage isomers. Our results suggest that these isomers show bond-stretch isomerism and that they have an identical spin state and an identical potential energy curve. Although the predominant electronic configurations of the isomers are similar, the frontier orbital characteristics are different, implying that we could anticipate an entirely different set of characteristic chemical reactions for each type of HOMO and LUMO.

• Journal of Power Electronics
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• 제6권3호
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• pp.245-252
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• 2006

This paper presents a method based on neural networks to detect the broken rotor bars and end rings of squirrel cage induction motors. At first, detection methods are studied, and then traditional methods of fault detection and dynamic models of induction motors by using winding function model are introduced. In this method, all of the stator slots and rotor bars are considered, thus the performance of the motor in healthy situations or breakage in each part can be checked. The frequency spectrum of current signals is derived by using Fourier transformation and is analyzed in different conditions. In continuation, an analytical discussion and a simple algorithm are presented to detect the fault. This algorithm is based on neural networks. The neural network has been trained by using information of a 1.1 KW induction motor. This system has been tested with a different amount of load torque, and it is capable of working on-line and of recognizing all normal and ill conditions.