• Title/Summary/Keyword: New correction factor

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Soft Switching Single Stage AC-DC Full Bridge Boost Converter Using Non-Dissipative Snubber (무손실 스너버 적용 소프트 스위칭 Single Stage AC-DC Full Bridge Boost 컨버터)

  • 김은수;조기연;김윤호;조용현;박경수;안호균;박순구
    • The Transactions of the Korean Institute of Power Electronics
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    • v.4 no.4
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    • pp.377-383
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    • 1999
  • A new soft switching single stage AC-DC full bridge boost converter with unit input power factor and isolated output i is presented in this paper. Due to the use of a non-dissipative snubber on the primary side, a single stage high-power f factor isolated full bridge boost converter has a significant reduction of switching losses in the main switching devices. The non-dissipative snubber adopted in this study consists of a snubber capacitor Cr, a snubber inductor Cr, a fast r recovery snubber diode Dr' and a commutation diode Dp. This paper presents the complete operating principles, t theoretical analysis and experimental results.

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A Study on PFC AC-DC Converter of High Efficiency added in Electric Isolation (절연형 고효율 PFC AC-DC 컨버터에 관한 연구)

  • Kwak, Dong-Kurl;Kim, Sang-Roan
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.7
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    • pp.1349-1355
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    • 2009
  • This paper is studied on a novel power factor correction (PFC) AC-DC converter of high efficiency by soft switching technique. The input current waveform in the proposed converter is got to be a sinusoidal form composed of many a discontinuous pulse in proportion to the magnitude of a ac input voltage under the constant switching frequency. Therefore, the input power factor is nearly unity and the control method is simple. The proposed converter adding an electric isolation operates with a discontinuous current mode (DCM) of the reactor in order to obtain some merits of simpler control, such as fixed switching frequency, without synchronization control circuit used in continuous current mode (CCM). To achieve the soft switching (ZCS or ZVS) of control devices, the converter is constructed with a new loss-less snubber for a partial resonant circuit. It is that the switching losses are very low and the efficiency of the converter is high, Particularly, the stored energy in a loss-less snubber capacitor recovers into input side and increases input current from a resonant operation. The result is that the input power factor of the proposed converter is higher than that of a conventional PFC converter. This paper deals mainly with the circuit operations, theoretical, simulated and experimental results of the proposed PFC AC-DC converter in comparison with a conventional PFC AC-DC converter.

High Power Factor Three-phase AC-DC Flyback Converter Module Using Zero Voltage Switching (영전압 스위칭을 이용한 고역률 3상 AC-DC Flyback 컨버터 모듈)

  • Lee, J.P.;Choi, J.Y.;Song, J.H.;Choy, I.;Yoon, T.Y.
    • Proceedings of the KIEE Conference
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    • 1999.07f
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    • pp.2701-2703
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    • 1999
  • A new mode of parallel operation of a modular 3-phase AC-DC Flyback converter for high power factor correction along with tight regulation is presented in this thesis. The converter offers input/output transformer isolation for safety, a unity input power factor for minimum reactive power, high efficiency and high power density for minimum weight and volume. Compared with previously developed 3-phase two-stage power converter, the advantage of the proposed converter does not require expensive high voltage and high current devices that are normally needed in popular boost type 3-phase converter. In this paper, a detailed small signal analysis of the modular 3-phase AC-DC flyback converter is provided for control purposes and also experimental results are included to confirm the validity of the analysis.

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A Study on InputOutput Waveform Solutions and Harmonics Analyses for a Novel PFC Step-up Converter (새로운 PFC 스텝-업 컨버터의 입출력 파형해석 및 고조파분석에 관한 연구)

  • Kwak Dong-Kurl
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.54 no.12
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    • pp.622-628
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    • 2005
  • This paper is given a full detail of mathematical analyses of input current and output voltage for a novel active type power factor correction (PFC) converter. These are compared with harmonics components of input current for a conventional PFC converter. The proposed PFC converter is constructed in using a new loss-less snubber circuit to achieve a soft switching of control device. Also the proposed converter for discontinuous conduction mode (DCM) eliminates the complicated circuit control requirement and reduces the size of components. The input current waveform in the proposed converter is got to be a sinusoidal form of discontinuous pulse in proportion to magnitude of ac input voltage under the constant duty cycle switching. Therefore, input power factor is nearly unity and the control method is simple. Particularly, the stored energy of loss-less snubber capacitor is recovered with input side and increases input current from resonant operation. The result is that input power factor of the proposed converter is higher than that of conventional PFC converter. Some simulative results on computer and experimental results are included to confirm the validity of the analytical results.

A new quasi-3D plate theory for free vibration analysis of advanced composite nanoplates

  • Smain, Bezzina;Aicha, Bessaim;Mohammed Sid Ahmed, Houari;Marc, Azab
    • Steel and Composite Structures
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    • v.45 no.6
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    • pp.839-850
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    • 2022
  • This paper presents an analytical solution to study the combined effect of non-local and stretching effect on the vibration of advanced functionally graded (FG) nanoplates. A new quasi-3D plate theory is presented; there are only five unknowns and any shear correction factor is used. A new displacement field with a new shear warping function is proposed. The equilibrium equations of the FG nanoplates are obtained using the Hamilton principle and solved numerically using the Navier technique. The material properties of functionally graded nanoplates are presumed to change according to the power-law distribution of ceramic and metal constituents. The numerical results of this work are compared with those of other published results to indicate the accuracy and convergence of this theory. Hence, a profound parameterstudy is also performed to show the influence of many parameters of the functionally graded nanoplates on the free vibration responses is investigated.

The Analysis of Shaft Deformation for Evaluating the Bearing Capacity of IGM Sosketed Drilled Shaft (IGM에 근입된 말뚝의 지지력 해석을 위한 기준침하량 결정방법 제안)

  • Chun, Byung-Sik;Kim, Won-Cheul;Seo, Deok-Dong
    • Journal of the Korean GEO-environmental Society
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    • v.5 no.3
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    • pp.17-30
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    • 2004
  • In this study, a new formula of settlement at the head of IGM was suggested and the applicability of suggested formula was verified with field test results. This suggested formula was the function of the settlement at the shaft head and the elastic compression of shaft. The applicability of suggested formula was verified with the result of in-situ load test. Also, the bearing capacity of drilled shaft with the IGM's theory was compared with those of classical theories. The results showed that classical method showed smaller values of bearing capacity than those of field load test data. The results of analysis also showed that the suggested formula and IGM's theory were applicable for the estimation of bearing capacity with the increase of shaft settlement. Especially, settlement correction factor(km), which reflects ground condition and load transfer characteristics, increases as the applying load and shaft deformation increase. This suggested formula was applicable for medium density or higher density of soil condition and km=1 means yielding load for firm soil condition.

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Improved method of lateral offset calculation for optical waveguide (광도파로의 곡률 반경에 따른 모드특성과 Lateral Offset 변화)

  • 박순룡;김우택;라상호;오범환
    • Korean Journal of Optics and Photonics
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    • v.9 no.6
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    • pp.408-412
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    • 1998
  • As the radius of curvature of curved optical waveguide gets smaller, the loss increases at the junction of linear-curved waveguide by the cross sectional mode mismatch. The concept of lateral offset has been used widely to minimize it, and simple method of maximum matching has been efficient for most cases of silica waveguide with low optical confinement and large radius of curvature. Here, we analyzed that the propagation mode characteristics of the lateral offset and propagation mode characteristics of general case with effective index method and Airy function solution. As the normalized frequency varies, mode characteristics changes near the boundary of 1/V=0.7 and the simple matching of gaussian profile might give -35% of error at most. We proposed improved method with a new correction factor to improve the mode mismatch problem of conventional methods for general cases, and showed the convenience and feasibility of this method for the calculation of the lateral offset.

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A Two-Phase Pressure Drop Calculation Code Based on A New Method with a Correction Factor Obtained from an Assessment of Existing Correlations (기존 상관관계식들의 평가를 통해 얻은 수정계수를 사용하는 새로운 방법에 기초한 2상류 압력강하 계산코드)

  • Chun, Moon-Hyun;Oh, Jae-Guen
    • Nuclear Engineering and Technology
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    • v.21 no.2
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    • pp.73-88
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    • 1989
  • Ten methods of the total two-phase pressure drop prediction based on five existing models and correlations have been examined for their accuracy and applicability to pressurized water reactor conditions. These methods were tested against 209 experimental data of local and bulk boiling conditions : Each correlations were evaluated for different ranges of pressure, mass velocity and Quality, and best performing models were identified for each data subsets. A computer code entitled 'K-TWOPD' has been developed to calculate the total two-phase pressure drop using the best performing existing correlations for a specific property range and a correction factor to compensate for the predicted error of the selected correlations. Assessment of this code shows that the present method fits all the available data within ±11% at a 95% confidence level compared with ±25%, for the existing correlations.

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Algorithm for the Low-Voltage Feeder Design in Consideration of Voltage Drop (전압강하를 고려한 저압간선의 설계 알고리즘)

  • 고영곤;최홍규;조계술
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.16 no.3
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    • pp.84-92
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    • 2002
  • A size of low-voltage conductor cables is determined by the voltage drop of a system the cable impedance and the cable ampacity based on temperature correction factor in accordance with the condition of cable installation. Therefore, the proper temperation correction factor according to the condition of cable installation should be applied to determining the cable ampacity and also the skin effect and proximity effect, along with the kind and size of conductor and the condition of cable installation, should be properly considered to analyze the proper value of resistance and the reactance of the conductors. This paper addresses the systematic design flow for determining the size of low voltage level con여ctor cables in calculating the voltage drop of a power system and proposes a new improved the calculating formula what error should be minimized in comparison with the general formula and which can be applied in design work for determining the size of conductor cables.

Thermal buckling of functionally graded sandwich plates using a new hyperbolic shear displacement model

  • Kettaf, Fatima Zohra;Houari, Mohammed Sid Ahmed;Benguediab, Mohamed;Tounsi, Abdelouahed
    • Steel and Composite Structures
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    • v.15 no.4
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    • pp.399-423
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    • 2013
  • In the present study, the thermal buckling behavior of functionally graded sandwich plates is studied using a new hyperbolic displacement model. Unlike any other theory, the theory is variationally consistent and gives four governing equations. Number of unknown functions involved in displacement field is only four, as against five in case of other shear deformation theories. This present model takes into account the parabolic distribution of transverse shear stresses and satisfies the condition of zero shear stresses on the top and bottom surfaces without using shear correction factor. Material properties and thermal expansion coefficient of the sandwich plate faces are assumed to be graded in the thickness direction according to a simple power-law distribution in terms of the volume fractions of the constituents. The core layer is still homogeneous and made of an isotropic material. The thermal loads are assumed as uniform, linear and non-linear temperature rises across the thickness direction. The results reveal that the volume fraction index, loading type and functionally graded layers thickness have significant influence on the thermal buckling of functionally graded sandwich plates.