• 제목/요약/키워드: Asymmetry Current

검색결과 118건 처리시간 0.028초

회전자 바 개방과 회전자 편심에 의한 단삼 유도 전동기의 전기 및 기계적 특성 해석 (Electromechanical Characteristics of a Squirrel Cage Induction Motor due to Broken Rotor Bars and Rotor Eccentricity)

  • 박상진;장정환;장건희;이용복;김창호
    • 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.

멀티 플랫폼 기반 온라인 응용의 데이터 제어 기법 (Data Control Methods of Online Application based on Multi-Platform)

  • 김진덕;진교홍
    • 컴퓨터교육학회논문지
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    • 제5권4호
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    • pp.79-89
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    • 2002
  • 기존의 고정 단발기 (PC)에서만 주로 행해지던 각종 다중 사용자 접속 온라인 응용이 최근 PC와 PDA, 휴대폰 등이 공동 작업을 수행하는 멀티 플랫폼 기반 온라인 응용으로 전환되고 있다. 그러나 지금까지 멀티 플랫폼 기반 온라인 응용은 다중 사용자의 공동 데이터의 동시 접근 및 각 클라이언트의 처리 능력과 통신 속도의 비대칭을 고려하지 않아 컨텐츠가 매우 단순한 실정이다. 이 논문에서는 멀티 플랫폼 기반 동시성 제어 기법, 다양한 클라이언트간의 변경 전파 프로토콜, 모바일 클라이언트의 특성을 고려한 객체 관리 기술을 제안하였다. 그리고 멀티 플랫폼 기반 채팅 프로그램을 제작하여 제안한 기법들이 적절히 동작함을 보였다.

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정밀저항시리즈 점용접에서 너깃의 대칭성에 미치는 공정변수의 영향 (The Effect of Process Parameter on the Symmetry of Nugget in Micro-resistance Series Spot Welding)

  • 조상명;김송미
    • Journal of Welding and Joining
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    • 제19권6호
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    • pp.622-629
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    • 2001
  • The aim of this experiment is to establish the method that obtains symmetrically two nuggets in microresistance series spot welding. The sheets of austenite stainless steel STS304 applied to various electronic parts were experimented by the inverter welding power source of polarity controllable type and by the twin head for left and right electrode force to be controlled separately. The experimental results were obtained as follows : 1) When series spot welding was carried out by DC 1 pulse as welding current with same electrode force at left and right, the asymmetry of nuggets was resulted from the larger nugget of the (-) pole because of the Peltier effect. The dynamic resistance of weld spot at left and right was appeared differently according to the growth of nuggets. 2) When AC 1 cycle by welding power source of polarity controllable type was applied, the nuggets were almost symmetrically formed. 3) In a twin head, if the electrode force of (-) pole was larger than that of (+) pole, the diameters of two nuggets became to same. It was confirmed that the dynamic resistance of (-) pole was decreased to the same level as it of (+) pole. 4) Although the forces of left and right electrode were same, and only DC 1 pulse was applied, symmetric nuggets were obtained if the conductivity of (+) pole was lower than it of (-) pole.

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성대결절 환자에 대한 10년간 임상 경험 (Ten years of clinical experience with the patients with vocal nodule)

  • 임혜진;김정규;최철희;최성희
    • 말소리와 음성과학
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    • 제9권4호
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    • pp.99-106
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    • 2017
  • Clinical data about vocal nodules have seldom been reported, even though vocal nodules are commonly diagnosed in outpatient speech and voice clinic. This study aims to investigate clinical characteristics of the patients who are diagnosed with vocal nodules. This study analyzed the data for 10 years from the 319 patients diagnosed with vocal nodules (45 males and 274 females with the mean age of 39.4 ranging from 2 to 83) in terms of gender, age, occupation, voice change initiation pattern, change with time, throat clearing, smoking history, type of voice abuse, acoustic analysis, maximum phonation time, GRBAS, and VHI. Thirteen patients (4.08%) had unilateral vocal nodule and 306 patients (95.9%) had bilateral vocal nodule, the majority of which had a pattern of asymmetry (73.9%). The glottal closure pattern was hourglass in 72.1% of patients, posterior chink in 17.9% of patients, and irregular in 7.9% of patients. The most common occupational category was professional voice users (43.4%). The voice abuse pattern included excessive talking in 96 patients (76.8%), loud voice in 78 (62.4%) patients, and excessive singing in 17 patients (21.6%). The patients showed worse scores in G, B, and S than in R and A for the GRBAS evaluation. The most recommended treatment for vocal nodules was voice therapy. The current clinical data will be helpful for treatment planning for the patients of vocal nodule.

모더니즘 후기 복식에 표현된 미의식 연구 (A Study on the Aesthetic Consciousness in the late Modernism Fashion)

  • 김정은;정흥숙
    • 복식
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    • 제51권6호
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    • pp.67-83
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    • 2001
  • The purpose of this study is to define the aesthetic consciousness in the late Modernism fashion which generated a sudden style change and craze, and to identify the essential meaning of the style. In order to achieve this the aesthetic approach was applied. Visual commonalities were sought between fashion and contemporary architecture, furniture, ceramic and metalware, to lead to a deeper insight into the aesthetic consciousness. Common visual characteristics are curvedness of the line, obliqueness of the line, asymmetry of the form, exaggeration of the form and symbolic nature of the form. The content which can be analogized from the visual characteristics are the beauty of the nature, the beauty of the glamourous feminity, the beauty of the ideal and the beauty of the creative personality. In the creating process, the existential aspect of human being became a focus of attention, and human being's subjectivity operated as a principal force. In the late Modernism fashion, the appreciator's aesthetic experience became more important, and the appreciator's psychological satisfaction and pleasure were considered in the creative process. Fashion, architecture and crafts, which fulfill functional duties in everyday life, facilitated the appreciator's aesthetic experience through empathy. This study inquires into the relationship between aesthetic consciousness and visual form. This study offers meaning because to uncover the connoted aesthetic consciousness in the late Modernism fashion is to pursue the roots of current aesthetic consciousness and it is hoped that in doing so this study will provide a basis for interpreting and understanding today's fashion style.

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Luminescence Study of Eu3+ Ions Doped BaMoO4 Nanoparticles

  • Bharat, L. Krishna;Lee, Soo Hyun;Yu, Jae Su
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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    • pp.415.2-415.2
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    • 2014
  • Cost-effective, robust devices for solid-state lighting industry that converts electricity to light revolutionize the current lighting industry. Phosphor materials used in these devices should be synthesized in a low-cost and effective method for use in WLEDs. In this presentation, the synthesis of Eu3+ ions doped BaMoO4 phosphor samples by a facile synthesis process for red component of WLEDs will be shown. The tetragonal phase of the host lattice was substantiated by the X-ray diffraction patterns. The morphological studies were carried out by using a field-emission scanning electron microscope and transmission electron microscope. These confirmed the formation of a shuttle like particles with perpendicular protrusions in the middle of the particle. The photoluminescence (PL) properties exhibited good emission with a high asymmetry ratio when excited with ultraviolet B wavelengths (~ 280-315 nm). The cathodoluminescence (CL) spectra showed similar results to the PL spectra, indicating the rich red emission. The results suggest that this phosphor is a good material as red region component in the development of tri-band UV excitation based WLEDs.

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Asymmetric Information Spillovers between Trading Volume and Price Changes in Malaysian Futures Market

  • Go, You-How;Lau, Wee-Yeap
    • The Journal of Asian Finance, Economics and Business
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    • 제1권3호
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    • pp.5-16
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    • 2014
  • This study aims to examine the dynamics of price changes and trading volume of Kuala Lumpur Options and Financial Futures Exchange (KLOFFE) from 2000 to 2008. With augmented analysis, our results support two hypotheses. First, under information spillover, our findings support noise traders' hypothesis as the time span for variance of past trading volume to cause variance of current return is found to be asymmetric under bull and bear markets. Second, looking at the dynamic relation between volume and volatility of price changes, our findings support Liquidity-Driven Trade hypothesis as past trading volume and subsequent volatility of return exhibit positive correlation. In terms of investors' behavior in response to the news, we find that investors are more risk taking in bull market and more risk reverse in bear market. Our study suggests that investors should adjust their strategy in the futures market in a dynamic manner as the time span of new information arrival is not consistent. Also, uninformed investors with information asymmetry should expect noninformational trading from informed investors to establish their desired positions for better liquid position.

Current Concepts in the Mandibular Condyle Fracture Management Part I: Overview of Condylar Fracture

  • Choi, Kang-Young;Yang, Jung-Dug;Chung, Ho-Yun;Cho, Byung-Chae
    • Archives of Plastic Surgery
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    • 제39권4호
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    • pp.291-300
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    • 2012
  • The incidence of condylar fractures is high,but the management of fractures of the mandibular condyle continues to be controversial. Historically, maxillomandibular fixation, external fixation, and surgical splints with internal fixation systems were the techniques commonly used in the treatment of the fractured mandible. Condylar fractures can be extracapsular or intracapsular, undisplaced, deviated, displaced, or dislocated. Treatment depends on the age of the patient, the co-existence of other mandibular or maxillary fractures, whether the condylar fracture is unilateral or bilateral, the level and displacement of the fracture, the state of dentition and dental occlusion, and the surgeonnds on the age of the patient, the co-existence of othefrom which it is difficult to recover aesthetically and functionally;an appropriate treatment is required to reconstruct the shape and achieve the function ofthe uninjured status. To do this, accurate diagnosis, appropriate reduction and rigid fixation, and complication prevention are required. In particular, as mandibular condyle fracture may cause long-term complications such as malocclusion, particularly open bite, reduced posterior facial height, and facial asymmetry in addition to chronic pain and mobility limitation, great caution should be taken. Accordingly, the authors review a general overview of condyle fracture.

Modified Anti-Windup PI 제어기와 Braking Mode를 이용한 SRM의 속도 제어 (Speed Control of Switch Reluctance Motor using Modified Anti-Windup PI Controller and Braking Mode)

  • 김학성;김연충;김재문;윤용호;원충연
    • 조명전기설비학회논문지
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    • 제21권6호
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    • pp.33-39
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    • 2007
  • 본 논문은 부하에 대한 빠른 응답 특성을 보이는 새로운 SRM 구동 토폴로지를 제안하였다. PI 제어기 출력이 포화될 때 windup 현상이 나타나고 그 결과로 성능이 저하된다. 따라서 전동기의 가변속 제어 성능을 위해 가속 시에는 개선된 Anti-Windup PI 제어기만을 사용하고 감소 시에는 추가로 부하의 특성을 고려하여 braking 동작을 사용하였다. 시뮬레이션 및 실험 결과는 속도 성능면에서 제안된 방식이 종래의 다른 제어 방식에 비해 우수함을 보여 준다.

Modeling, Analysis, and Enhanced Control of Modular Multilevel Converters with Asymmetric Arm Impedance for HVDC Applications

  • Dong, Peng;Lyu, Jing;Cai, Xu
    • Journal of Power Electronics
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    • 제18권6호
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    • pp.1683-1696
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    • 2018
  • Under the conventional control strategy, the asymmetry of arm impedances may result in the poor operating performance of modular multilevel converters (MMCs). For example, fundamental frequency oscillation and double frequency components may occur in the dc and ac sides, respectively; and submodule (SM) capacitor voltages among the arms may not be balanced. This study presents an enhanced control strategy to deal with these problems. A mathematical model of an MMC with asymmetric arm impedance is first established. The causes for the above phenomena are analyzed on the basis of the model. Subsequently, an enhanced current control with five integrated proportional integral resonant regulators is designed to protect the ac and dc terminal behavior of converters from asymmetric arm impedances. Furthermore, an enhanced capacitor voltage control is designed to balance the capacitor voltage among the arms with high efficiency and to decouple the ac side control, dc side control, and capacitor voltage balance control among the arms. The accuracy of the theoretical analysis and the effectiveness of the proposed enhanced control strategy are verified through simulation and experimental results.