• Journal of Communications and Networks
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• 제8권3호
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• pp.351-359
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• 2006

In this article, we present a new slow-start variant, which improves the throughput of transmission control protocol (TCP) Vegas. We call this new mechanism Gallop-Vegas because it quickly ramps up to the available bandwidth and reduces the burstiness during the slow-start phase. TCP is known to send bursts of packets during its slow-start phase due to the fast window increase and the ACK-clock based transmission. This phenomenon causes TCP Vegas to change from slow-start phase to congestion-avoidance phase too early in the large bandwidth-delay product (BDP) links. Therefore, in Gallop-Vegas, we increase the congestion window size with a rate between exponential growth and linear growth during slow-start phase. Our analysis, simulation results, and measurements on the Internet show that Gallop-Vegas significantly improves the performance of a connection, especially during the slow-start phase. Furthermore, it is implementation feasible because only sending part needs to be modified.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.631-632
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• 2006

This paper is written by research for the transient characteristics of the Single-phase Line-start permanent Magnet. The Single-phase Line-start permanent Magnet is most likely to substitute for Single-phase Induction Motor which is used about many appliance currently, because that has good points. For example, It has a Line-start of ability and a High-efficiency. And it need not power convergence device. The rotor of The Single-phase Line-start permanent Magnet has cage-bar with permanent magnet. This motor is started by cage-bar. When it entered synchronous condition, the rotor is rotated by the permanent magnet. But the design of the permanent magnet is very important, because the breaking torque of the permanent magnet interrupt to start a rotor. Finally, if Flux Barrier is not concerned, we do not get result of our object. Therefore this thesis is concerned about Flux Barrier.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권6호
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• pp.262-270
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• 2003

In this paper, the characteristics of single-phase line-start permanent magnet synchronous motor driven by constant voltage are analyzed on d-q axis vector diagram and compared with that of current controlled motor. The coupled method of symmetrical coordinates and d-q axis voltage equation are applied to the analysis method like the analysis of single-phase induction motor. From the result of the analysis, it is seen that motors driven by constant voltage source have effects on not only the amplitude of current and torque but also current and current phase angle, so overall characteristics such as power factor and load angle are affected by circuit parameters. For precise analysis and design of single-phase line-start synchronous motor, its characteristics should be analyzed on d-q axis vector plan in consideration of the variation of circuit parameters.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권2호
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• pp.53-60
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• 2003

This paper deals with steady-state analysis of a single-phase line-start permanent magnet synchronous motor. In order to analyze the steady-state characteristics, the asymmetric single-phase line-start synchronous motor is converted to the symmetric two-phase synchronous motor, that is, the asymmetric magnetic field is separated from the positive and the negative symmetric components using symmetrical-component theory. The analysis method of the synchronous motor on the d-q axis coordinates is used for the positive component and the equivalent circuit of the induction motor is applied for the negative component analysis. Moreover, d-q axis inductance considering current phase angle is applied to positive component analysis for precise characteristic analysis. In order to validate the proposed analysis method, the analysis results are compared with the experimental results.

• 조명전기설비학회논문지
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• 제21권3호
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• pp.125-131
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• 2007

가전분야에서의 전동기 효율향상을 통한 에너지 소비절감 효과는 상당히 크지만 이를 위한 전동기의 설계/해석 기술 확보가 아직은 미흡한 상태이다. 이에 따라 유도형 동기전동기가 제안되었지만, 유도형 동기 전동기는 유도전동기와 통기전동기의 특성을 동시에 가지고 있어, 해석 및 설계가 쉽지 않다. 따라서 본 논문에서는 기존의 냉장고 압축기용 전동기인 단상유도전동기를 대처할 수 있는 단상 유도형 동기전동기를 이용해 파라미터에 따라 특성이 어떻게 바뀌는가에 대해 서술하였다. 그에 따라 단상유도전동기의 정상상태 특성을 해석하고 제안모델의 성능을 기존모델과 비교하고 실험하여 해석결과의 신뢰성을 검증한다. 또한 본 논문에서는 제안모델의 기존 고정자 형상이나 권선 스팩을 유지하고 회전자의 형상이나 구조만을 변경시켜 성능향상을 도모하였다. 해석방법으로는 전자장 수치 해석적인 방법으로 널리 이용되고 있는 유한요소법(Finite Element Method : FEM)을 이용하였다.

• 전기학회논문지
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• 제65권1호
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• pp.58-64
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• 2016

In this paper, the design of rotor shape was performed for improvement of start-up characteristics and efficiency in single-phase LSPM. In order to improve the start-up characteristics, shape of rotor aluminium cage bar was changed. Through arrangement of permanent magnets and installation of flux barriers, it was performed torque ripple reduction and efficiency improvement. Cogging torque and back-EMF is calculated by the no-load analysis, start-up time is calculated by the start-up state analysis, efficiency and torque ripple is calculated by steady state analysis. The characteristics of the motor were calculated through FEM.

• 벤처창업연구
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• 제15권4호
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• pp.109-120
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• 2020

본 연구는 창업자들이 지각하는 정부의 창업지원에 대한 공정성이 창업지원의 만족도 및 경영성과에 어떠한 영향을 미치는가를 살펴보고 이러한 영향이 창업기업의 성장단계별로 차이가 있는지를 확인하는 것이다. 본 연구는 지난 5년 내에 정부의 창업지원을 받은 창업기업을 대상으로, 총 611부의 데이터를 본 연구에 사용하였다. 수집된 자료는 SPSS와 AMOS를 이용하여 분석하였다. 본 연구에서 사용된 공정성은 많은 연구에서 사용하는 방식과 동일하게 절차적 공정성, 분배적 공정성, 상호작용적 공정성의 세 유형으로 구분하였으며, 세 유형의 공정성이 창업지원 사업 만족도에 미치는 영향을 분석하였다. 또한 정부의 창업지원 만족도와 경영성과 간의 관계를 분석하였는데, 경영성과는 응답자 자신의 사업에 대한 만족도로 평가하였다. 그리고 창업단계는 창업기, 초기성장기, 정체기/데스벨리, 고도성장기로 구분하였으며, 창업단계별 정부지원사업의 공정성과 만족도 간의 관계를 분석하였다. 분석결과, 모든 공정성 개념은 창업지원사업만족도에 정(+)의 영향을 미치고, 창업지원사업만족도는 경영성과에 정(+)의 영향을 미치는 것으로 나타났다. 그러나 창업단계별로는 차이가 있었는데, 창업기에는 절차적 공정성이, 초기성장기에는 절차적공정성과, 상호작용적 공정성이, 정체기/데스벨리에는 모든 공정성 개념이 창업지원사업만족도에 영향을 미쳤지만, 고도성장기에는 공정성 개념이 모두 창업지원만족도에 영향을 미치지 못하였다. 그리고 창업지원사업만족도와 경영성과 간의 관계에서는 창업단계에 관계없이 정의 영향을 미쳤다. 이러한 연구의 결과는 정부의 창업지원 사업에 대한 창업자의 공정성 지각을 적용하여, 창업지원에 대한 체계적인 시스템을 구축하는 데 도움이 될 것이며, 창업자에게는 창업단계별 창업성과를 증대시키기 위한 방안을 모색하는 데도 기여하는 바가 클 것이다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.831-833
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• 2001

Line-start motor has ability to start itself without using other methods, so, it is important to predict starting performance accurately. In this paper, the starting characteristics of single-phase capacitor-start, capacitor-run line-start motor was calculated by combination of d-q axis voltage equations and mechanical dynamic equations. D-q axis inductances of this machine varied with current phase angle and amplitude are considered. The validity of analysis method verified by comparing to test results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.933-935
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• 2003

The single-phase line start permanent magnet motor(LSPM) have a rotor cage bar for induction starting and permanent magnets, providing synchronous torque. So, LSPM is vary complex and difficult to analysis transient characteristics and rotor design. In this paper, F.E.M analysis about single-phase line start permanent magnet motor and compare of the single-phase line start permanent magnet synchronous motor's transient characteristics by size and position of rotor bar.

• Journal of Electrical Engineering and Technology
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• 제1권4호
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• pp.490-495
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• 2006

In this research, the design procedure and the design method of a single-phase line-start permanent magnet motor (LSPM) are proposed. In the design procedure, the permanent magnet is designed first and the windings and capacitors are designed later. As well, the points of design of each design parameter are explained. In the design of the single-phase LSPM, the equivalent circuit method is combined with the finite element method (FEM) because it has a shorter analysis time than FEM. The 400 watts single-phase LSPM is designed and manufactured. The characteristics of the manufactured single-phase LSPM are analyzed and experimented. From the analysis result and the experiment result, it is verified that the design procedure and the design method of the single-phase LSPM is valid.