• 제목/요약/키워드: 1st Frequency

검색결과 943건 처리시간 0.028초

United Electromagnetic Characteristics and Online Monitoring Method of Static Air-gap Eccentricity of Turbo-Generator

  • Tang, Gui-Ji;Ke, Meng-Qiang;He, Yu-Ling;Wang, Fa-Lin
    • Journal of Electrical Engineering and Technology
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    • 제11권6호
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    • pp.1614-1627
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    • 2016
  • The purpose of this paper is to investigate the united Electromagnetic characteristics for the effective monitoring on the static air-gap eccentricity (SAGE) of turbo-generator. Different from other studies, this paper not only studies on the unbalanced magnetic pull (UMP) and the vibration characteristics of the stator and the rotor, but also investigates the harmonic features of the magnetic flux density and the circulating current inside the parallel branches (CCPB). The theoretical calculation, together with the finite-element-method (FEM) simulation and the experiment verification, is taken for a SDF-9 type non-salient generator. It is shown that, when SAGE occurs, apparent double-frequency UMP and vibrations will be produced both on the stator and the rotor, while the CCPB will have an obvious increment at the $1^{st}$ harmonic component. In addition, the amplitude of the magnetic flux density will be of cosine distribution in the circumferential position of the air-gap, while in normal condition it is a constant. Moreover, the pass-band amplitude, together with the $1^{st}$ harmonic of the magnetic flux density, will be enlarged as well. These united electromagnetic characteristics can be used as the diagnosis and monitoring criterion for SAGE.

PQ Control of Micro Grid Inverters with Axial Voltage Regulators

  • Chen, Yang;Zhao, Jinbin;Qu, Keqing;Li, Fen
    • Journal of Power Electronics
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    • 제15권6호
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    • pp.1601-1608
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    • 2015
  • This paper presents a PQ control strategy for micro grid inverters with axial voltage regulators. The inverter works in the voltage-controlled mode and can help improve the terminal power quality. The inverter has two axial voltage regulators. The 1st regulator involves the output voltage amplitude and output impedance, while the 2nd regulator controls the output frequency. The inverter system is equivalent to a controllable voltage source with a controllable inner output impedance. The basic PQ control for micro grid inverters is easy to accomplish. The output active and reactive powers can be decoupled well by controlling the two axial voltages. The 1st axial voltage regulator controls the reactive power, while the 2nd regulator controls the active power. The paper analyses the axial voltage regulation mechanism, and evaluates the PQ decoupling effect mathematically. The effectiveness of the proposed control strategy is validated by simulation and experimental results.

Two Cases of Primary Splenic Hydatid Cyst in Greece

  • Vezakis, Antonios;Dellaportas, Dionysios;Polymeneas, George;Tasoulis, Marios Konstantinos;Chondrogiannis, Constantinos;Melemeni, Aikaterini;Polydorou, Andreas;Fragulidis, George Panagiotis
    • Parasites, Hosts and Diseases
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    • 제50권2호
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    • pp.147-150
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    • 2012
  • Cystic disease of the spleen is an uncommon entity in general population. Most cases result from parasitic infection by Echinococcus granulosus, a form called splenic hydatid disease (SHD), with a reported frequency of 0.5-6.0% within abdominal hydatidosis. On the contrary, an isolated splenic involvement of hydatid disease is very uncommon even in endemic regions. Two cases of primary SHD managed with open and laparoscopic radical surgery in our department are reported herein. Primary SHD is a rare entity with non-specific symptoms underlying clinical suspicion by the physician for prompt diagnosis. Surgical treatment is the mainstay therapy, while laparoscopic approach when feasible is safe, offering the advantages of laparoscopic surgery.

에러 분석을 통한 사용자 중심의 메뉴 기반 인터페이스 설계 (Design of Menu Driven Interface using Error Analysis)

  • 한상윤;명노해
    • 대한인간공학회지
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    • 제23권4호
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    • pp.9-21
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    • 2004
  • As menu structure of household appliance is complicated, user's cognitive workload frequently occurs errors. In existing studies, errors didn't present that interpretation for cognitive factors and alternatives, but are only considered as statistical frequency. Therefore, error classification and analysis in tasks is inevitable in usability evaluation. This study classified human error throughout information process model and navigation behavior. Human error is defined as incorrect decision and behavior reducing performance. And navigation is defined as unrelated behavior with target item searching. We searched and analyzed human errors and its causes as a case study, using mobile phone which could control appliances in near future. In this study, semantic problems in menu structure were elicited by SAT. Scenarios were constructed by those. Error analysis tests were performed twice to search and analyze errors. In 1st prototype test, we searched errors occurred in process of each scenario. Menu structure was revised to be based on results of error analysis. Henceforth, 2nd Prototype test was performed to compare with 1st. Error analysis method could detect not only mistakes, problems occurred by semantic structure, but also slips by physical structure. These results can be applied to analyze cognitive causes of human errors and to solve their problems in menu structure of electronic products.

Phentermine 및 Phendimetrazine으로 유발된 정신병적 장애 및 양극성 장애 증례군 연구 (Phentermine and Phendimetrazine-Induced Psychotic Disorder and Bipolar Disorder: A Case Series)

  • 김수영;김태석;김대진;채정호;이창욱;주수현
    • 생물정신의학
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    • 제29권1호
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    • pp.22-31
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    • 2022
  • Objectives Recently, weight loss has emerged as a national concern in South Korea, and this has resulted in an increase in the frequency of use of central nervous system (CNS)-stimulating appetite suppressants. This study aimed to collect cases of psychotic disorders and bipolar disorders triggered by phentermine and phendimetrazine and explore the clinical features and courses. Methods In this retrospective study, we analyzed the electronic medical records of patients and selected eight patients who developed psychotic symptoms and manic symptoms for the first time after taking phentermine and phendimetrazine. All cases were reviewed, and their clinical features and course were summarized. Results All eight patients developed psychotic symptoms, and one had accompanying manic symptoms. The final diagnosis was appetite-suppressant-induced psychotic disorder in four patients, schizophrenia in three, and appetite-suppressant-induced bipolar disorder in one. In addition, three patients were diagnosed as having substance-use disorder. The key psychotic symptoms of these patients were hallucinations and paranoia. Conclusions These case findings suggest that phentermine and phendimetrazine can cause psychotic disorder, bipolar disorder, or substance use disorder and that medical professionals and the public should practice caution when prescribing and using these drugs.

Numerical Analysis of Three Dimensional Supersonic Flow around Cavities

  • Woo Chel-Hun;Kim Jae-Soo;Kim Jong-Rok
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2006년도 PARALLEL CFD 2006
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    • pp.311-314
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    • 2006
  • The supersonic flow around tandem cavities was investigated by three- dimensional numerical simulations using the Reynolds-Averaged Navier-Stokes(RANS) equation with the $\kappa-\omega$ thrbulence model. The flow around a cavity is characterized as unsteady flow because of the formation and dissipation of vortices due to the interaction between the freestream shear layer and cavity internal flow, the generation of shock and expansion waves, and the acoustic effect transmitted from wake flow to upstream. The upwind TVD scheme based on the flux vector split using van Leer's limiter was used as the numerical method. Numerical calculations were performed by the parallel processing with time discretizations carried out by the 4th-order Runge-Kutta method. The aspect ratio of cavities are 3 for the first cavity and 1 for the second cavity. The ratio of cavity interval to depth is 1. The ratio of cavity width to depth is 1 in the case of three dimensional flow. The Mach number and the Reynolds number were 1.5 and $4.5{\times}10^5$, respectively. The characteristics of the dominant frequency between two-dimensional and three-dimensional flows were compared, and the characteristics of the second cavity flow due to the fire cavity flow cavity flow was analyzed. Both two dimensional and three dimensional flow oscillations were in the 'shear layer mode', which is based on the feedback mechanism of Rossiter's formula. However, three dimensional flow was much less turbulent than two dimensional flow, depending on whether it could inflow and outflow laterally. The dominant frequencies of the two dimensional flow and three dimensional flows coincided with Rossiter's 2nd mode frequency. The another dominant frequency of the three dimensional flow corresponded to Rossiter's 1st mode frequency.

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악성 종양 관련 일측성 성대 마비 환자에서 고식적 Hyaluronic Acid 성대 주입 성형술의 유용성 (Benefits of Palliative Office-Based Hyaluronic Acid Injection Laryngoplasty in Cancer-Related Unilateral Vocal Cord Paralysis Patients)

  • 김고운;박영학;주영훈;김상연;심미란;황연신;선동일
    • 대한후두음성언어의학회지
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    • 제29권1호
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    • pp.30-36
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    • 2018
  • Background and Objectives : The effect of palliative injection laryngoplasty in cancer-related unilateral vocal cord paralysis patients on voice and swallowing function is uncertain and there are few previous studies of its suitability, benefits as a palliative treatment option. The purpose of this study is to confirm the objective results of voice and swallowing function after palliative office-based hyaluronic acid injection laryngoplasty in cancer-related unilateral vocal cord paralysis patients. Materials and Method : 36 patients who had unilateral vocal cord paralysis from non-thyroidal, extralaryngeal neoplasms were included in this study. To evaluate the clinical outcome, we analyzed perceptual GRBAS grading, acoustic analysis, aerodynamic study, Electroglottography (EGG), Voice Handicap Index (VHI-30) about voice function and disability rating scale (DRS), gastric tube dependency, aspiration pneumonia about swallowing function and 36-Item Short Form Survey version 2 (SF-36v2) about quality of life. Results : In GRBAS scale, G (p<0.001), R (p=0.004), B (p=0.001), A (p=0.011), and S (p=0.007) showed significant improvement. Jitter, shimmer, speaking fundamental frequency, maximal phonation time, VHI-30, DRS score, gastric tube dependency, aspiration pneumonia, and SF-36v2 were significantly improved after injection (p=0.016, p=0.011, p=0.045, p=0.005, p<0.001, p<0.001 p=0.003, p<0.001, and p<0.001 respectively). Conclusion : From this study we concluded office-based hyaluronic acid injection can be used as a useful palliative treatment option in cancer-related ill patients with unilateral vocal cord paralysis. Palliative hyaluronic acid injection laryngoplasty avoids the need for tube feeding, thus reducing the risk of aspiration pneumonia. These outcomes are accompanied by significant improvement in voice quality.

정상적(正常的)인 한우(韓牛)의 심전도(心電圖)에 관(關)한 연구(硏究) I. 표준지유도(標準肢誘導) (Studies on electrocardiogram of the normal Korean native cattle I. Standard limb leads)

  • 최인혁;정인성;김남수;서두석
    • 대한수의학회지
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    • 제33권4호
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    • pp.719-734
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    • 1993
  • The electrocardiographic(ECG) parameters on the standard limb leads in the normal Korean native cattle have been measured with a 3 channel Electrocardiograph built in a computed analysis. The study was conducted on the animals 98 heads of mean age of 17.7 months. Conduction parameters, waves, intervals and segments have been recorded. The recordings were analyzed as to shape and amplitude of the P and T waves and the components of the QRS complex. Heart rate was recorded by the Electrocardiogram which were a mean of $80.4{\pm}11.6beats/min$. And the younger had a higher heart rate than the older one. Average conduction times in the RP, the QRS complex and the QTc interval recorded $166.7{\pm}23.1msec.$, $79.7{\pm}8.8msec.$ and $395.5{\pm}30.4msec.$, in the P and T wave duration recorded $70.1{\pm}13.5msec.$ and $97.6{\pm}16.9msec.$, and in the PR and ST segment duration recorded $97.9{\pm}23.5msec.$ and $173.9{\pm}40.3msec.$, respectively. The wave forms in each lead observed various types. The amplitudes of wave type showed the highest frequency in each lead that were analyzed as follow : 1. In P wave, amplitudes of the positive type showed the frequency of 65.3%, 82.7% and 52.0% in leads I, II and III that were $103.1{\pm}47.8{\mu}V$, $115.2{\pm}37.3{\mu}V$ and $67.4{\pm}26.9{\mu}V$, and it showed the frequency of 54.1% and 85.7% in the leads aVL and aVF that were $63.7{\pm}23.0{\mu}V$, $88.0{\pm}83.6{\mu}V$, respectively. Average amplitude of the negative type showed the frequency of 78.6% in lead aVR which was $99.3{\pm}38.0{\mu}V$. 2. Average amplitude of the QRS complex were from $362.8{\pm}177.7{\mu}V$ to $532.8{\pm}253.9{\mu}V$(mean of $449.1{\pm}57.2{\mu}V$) that in all leads except lead I were manifested the Low-Voltage QRS complex(below 0.5mV). Average amplitudes of each wave type in the QRS complex aere $-50.2.4{\pm}258.2{\mu}V$ and $-428.6{\pm}195.1{\mu}V$ in the QS groups type that showed a frequency of 66.3%, 70.4% in the leads I and aVL, were $451.1{\pm}20.4.0{\mu}V$, $387.6{\pm}175.8{\mu}V$ and $299.3{\pm}146.5{\mu}V$ in the R groups type that showed a frequency of 48.0%, 53.1% and 34.7% in the leads III, aVR and aVF, and were $-307.5{\pm}180.3{\mu}V$, $201.4{\pm}77.2{\mu}V$ in the QR wave type which showed a frequency of 39.8% in lead II, respectively. 3. In T wave, amplitude of the positive type showed the frequency of 50.0%, 82.7%, 51.0% and 57.1% in leads II, III aVR and aVF which were $214.9{\pm}115.6{\mu}V$, $188.5{\pm}119.3{\mu}V$, $191.0{\pm}93.7{\mu}V$ and $165.7{\pm}91.9{\mu}V$, and the negative type showed a frequecny of 66.3% and 72.5% in leads I and aVL. that were $221.3{\pm}112.5{\mu}V$, $-173.6{\pm}86.7{\mu}V$, respectively. 4. Amplitude of ST segment in leads I, II and III were a mean of $-12.2{\pm}37.2{\mu}V$, $17.5{\pm}42.6{\mu}V$ and $28.3{\pm}40.4{\mu}V$, in leads aVR, aVL and aVF were $-3.9{\pm}32.5{\mu}V$, $-15.9{\pm}35.6{\mu}V$ and $26.2{\pm}37.5{\mu}V$, respectively.

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모드형상을 이용한 전단형 건물의 손상 위치 추정 (Damage Location Detection of Shear Building Structures Using Mode Shape)

  • 유석형;이홍규
    • 한국구조물진단유지관리공학회 논문집
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    • 제17권1호
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    • pp.124-132
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    • 2013
  • 손상된 구조물의 동적응답신호를 역해석함으로써 손상위치와 정도를 파악할 수 있다. 일반적으로 손상 전 후 고유진동수의 변화로부터 강성의 감소량을 구하고, 모드형상의 변화로부터 손상위치를 파악할 수 있다. 토목구조물의 경우 동적 응답신호로부터 손상을 검출코자 하는 연구가 상당히 진행되었으며 실용화 되었다. 그러나 건축구조물의 경우 몇 가지 문제로 인하여 이에 대한 연구가 활발히 진행되지 못하고 있다. 본 연구에서는 모드형상을 이용한 전단형 건물의 손상위치 추적방안을 제시 하고자 한다. 전단형 건물의 손상 전 후 1차 모드강성의 차이를 이용한 손상위치 추적지수를 이론적으로 고찰하였으며, 이를 Matlab 또는 MIDAS GENw와 같은 수치해석모델에 적용함으로써 손상위치추적기법의 타당성을 검증하였다. 또한 소형 진동대 실험을 수행하고 실측된 동적응답신호를 이용하여 손상위치를 추적함으로써 실구조물에 대한 적용성을 검토하였다. 진동대 실험결과 층강성이 25% 감소할 때 1차 모드 진동수는 12%증가 하였으며, 손상위치 지수는 손상 층에서 마이너스 값을 나타내었다.

전방향 복사패턴의 이중대역 프린트형 모노폴안테나 (Printed Monopole Antenna of Dual band for Omni-diractional Radiation Patterns)

  • 이현진;임영석
    • 대한전자공학회논문지TC
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    • 제40권11호
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    • pp.99-104
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    • 2003
  • 인쇄형 모노폴 구조를 이용하여 PCS와 IMT2000대역인 이중 주파수 대역의 프린트형 모노폴 안테나를 설계 및 제작하였으며, 이중대역을 얻기 위하여 기존의 단일 모노폴 구조를 수정한 이중 모노폴 구조를 제안하였다. 제안된 안테나는 기존의 모노폴 안테나와 동일한 무지향 복사 특성을 가지며 평면으로 구현되어 모노폴 안테나 보다 크기가 작고 높은 이득을 갖는다. 두개의 단일 모노폴은 상호 임피던스 매칭을 위한 스터브로 작용하여 임피던스 매칭이 용이하고 이에 따른 대역폭의 증가를 향상시킬 수 있었다. 안테나의 대역폭은 VSWR(equation omitted)1.5를 기준하여 150㎒ (1.74∼1.89〔㎓〕)와 290㎒(1.95∼2.24〔㎓〕)의 결과를 얻었다. 이는 PCS대역(1.75∼l.87〔㎓〕)과 IMT2000대역(1.92∼2.17〔㎓〕)을 충족시킬 수 있다.