• Title/Summary/Keyword: New correction factor

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Environmental Fatigue Evaluation for Thermal Stratification Piping of Nuclear Power Plants (열성층을 포함하는 원자력발전소 배관의 환경피로평가)

  • Kim, Taesoon;Kim, Kyuhyung
    • Journal of the Korean Society of Safety
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    • v.33 no.5
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    • pp.164-169
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    • 2018
  • A detailed fatigue evaluation procedure was developed to mitigate the excessive conservativeness of the conventional environmental fatigue evaluation method for the pressurizer spray line elbow of domestic new nuclear power plants. The pressurizer spray line is made of austenitic stainless steel, which is relatively sensitive to the environmentally assisted fatigue, and has a low degree of design margin in terms of environmentally assisted fatigue due to the thermal stratification phenomenon on the pipe cross section as a whole or locally. In this study, to meet the environmental fatigue design requirements of the pressurizer spray line elbow, the new environmental fatigue evaluation has been performed, which used the ASME Code NB-3200-based detailed fatigue analysis and the environmental fatigue correction factor instead of the existing NB-3600 evaluation method. As a result, the design requirements for environmentally assisted fatigue were met in all parts of the pressurizer spray line elbow including the fatigue weakened zones by thermal stratification.

New Isolated Single-Phase AC-DC Converter for Universal Input Voltage

  • Lee, Ming-Rong;Yang, Lung-Sheng;Lin, Chia-Ching
    • Journal of Power Electronics
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    • v.13 no.4
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    • pp.592-599
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    • 2013
  • This paper investigates a new isolated single-phase AC-DC converter, which integrates a modified AC-DC buck-boost converter with a DC-DC forward converter. The front semi-stage is operated in discontinuous conduction mode (DCM) to achieve an almost unity power factor and a low total harmonic distortion of the input current. The rear semi-stage is used for step-down voltage conversion and electrical isolation. The front semi-stage uses a coupled inductor with the same winding-turn in the primary and secondary sides, which is charged in series during the switch-on period and is discharged in parallel during the switch-off period. The discharging time can be shortened. In other words, the duty ratio can be extended. This semi-stage can be operated in a larger duty-ratio range than the conventional AC-DC buck-boost converter for DCM operation. Therefore, the proposed converter is suitable for universal input voltage (90~264 Vrms) and a wide output-power range. Moreover, the voltage stress on the DC-link capacitor is low. Finally, a prototype circuit is implemented to verify the performance of the proposed converter.

A Three-Phase Four-Wire DSTATCOM for Power Quality Improvement

  • Singh, Bhim;Jayaprakash, P.;Kothari, D.P.
    • Journal of Power Electronics
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    • v.8 no.3
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    • pp.259-267
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    • 2008
  • Power quality improvement in a three-phase four-wire system is achieved using a new topology of DSTATCOM (distribution static compensator) consisting of a star/delta transformer with a tertiary winding and a three-leg VSC (voltage source converter). This new topology of DSTATCOM is proposed for power factor correction or voltage regulation along with harmonic elimination, load balancing and neutral current compensation. A tertiary winding is introduced in each phase for a delta connected secondary in addition to the star-star windings and this delta connected winding is responsible for neutral current compensation. The dynamic performance of the proposed DSTATCOM system is demonstrated using MATLAB with its Simulink and Power System Blockset (PSB) toolboxes under varying loads. The capacitor supported DC bus of the DSTATCOM is regulated to the reference voltage under varying loads.

A New Zero Voltage Transition Bridgeless PFC with Reduced Conduction Losses

  • Mahdavi, Mohammad;Farzanehfard, Hosein
    • Journal of Power Electronics
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    • v.9 no.5
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    • pp.708-717
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    • 2009
  • In this paper a new zero voltage transition PWM bridgeless PFC is introduced. The auxiliary circuit provides soft switching condition for all semiconductor devices. Also, in the resonant path of the auxiliary circuit, only two semiconductor devices exist. Therefore the resonant conduction losses are low. Furthermore, the auxiliary circuit semiconductor elements consist of only one diode and one switch. The proposed auxiliary circuit is applied to a bridgeless PFC converter to further reduce conduction and switching losses. In this paper, the operating modes of this converter are explained and the resulting ideal and simulation waveforms are shown. The presented experimental results justify the theoretical analysis.

New Single Stage PFC Full Bridge Converter (새로운 단일전력단 역률보상 풀브리지 컨버터)

  • 임창섭;권순걸;조정구;송두익
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.52 no.12
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    • pp.655-660
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    • 2003
  • This paper proposes new single stage power factor correction (PFC) full bridge converter. The proposed converter is combined previous ZVS full bridge DC/DC converter with two inductors, two diodes, two magnetic coupling transformer for PFC. This process of power is isolated from the source and also regulate stable DC output voltage in a category. In this topology, the voltage stress of main switches is reduced by zero voltage switching. Moreover, the proposed converter doesn't need active PFC switch and auxiliarly circuits, like control and gating board, so it could decrease the size and cost and increase the efficiency.

Method and Apparatus for Digital Auto Convergence of Projection Video Display

  • Tai, Wen-Chih;Mo, Chi-Neng;Juan, Chang-Jung;Tsai, Ming-Jong
    • 한국정보디스플레이학회:학술대회논문집
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    • 2005.07b
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    • pp.1171-1174
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    • 2005
  • This thesis provides a new digital convergence method and apparatus which uses area photo sensor and new analog to digital algorithmic to identify the correct digital pattern position factor of the projection system. This method and apparatus can be applied to the convergence correction in a TV receiver with a display that comprises a display screen with photo sensors positioned adjacent to screen edges. It also can be applied to the manufacture process detection of the projection system to adjust the associative convergence parameter. In this paper, demonstrate how this convergence detecting algorithmic was implemented with four area photo sensors of special designed pattern to the rear projection CRT TV.

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Estimation of Denominators- a New Approach for Calculating of Various Rates in Cancer Registries

  • Haroon, A.S.;Gupta, S.M.;Tyagi, B.B.;Farhat, J.
    • Asian Pacific Journal of Cancer Prevention
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    • v.13 no.7
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    • pp.3229-3232
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    • 2012
  • In this study, cancer incidence data were assessed to provide various rates of five year age groups for a given year, lying between two census years. The individual exponential growth rate method is most useful in both population-based and non-population cased cancer registries in India to estimate the population by five yearly age groups and also find the rates of crude rates, age standard rates and cumulative rates. This method has been shown to endure from bias and often results sacrificing the overall growth rate and correction factor must be needful in five year age group population to maintain it. A second method, the difference distribution method is also able to maintain the overall growth rate and overcome the bias in estimation of five yearly age group populations. From this point of view these methods serving a new technique for population estimation by five yearly age groups for inter census years.

A New Zero-Voltage-Switching Bridgeless PFC, Using an Active Clamp

  • Ramezani, Mehdi;Ghasedian, Ehsan;Madani, Seyed M.
    • Journal of Power Electronics
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    • v.12 no.5
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    • pp.723-730
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    • 2012
  • This paper presents a new ZVS single phase bridgeless (Power Factor Correction) PFC, using an active clamp to achieve zero-voltage-switching for all main switches and diodes. Since the presented PFC uses a bridgeless rectifier, most of the time, only two semiconductor components are in the main current path, instead of three in conventional single-switch configurations. This property significantly reduces the conduction losses,. Moreover, zero voltage switching removes switching loss of all main switches and diodes. Also, auxiliary switch turns on zero current condition. The presented converter needs just a simple non-isolated gate drive circuitry to drive all switches. The eight stages of each switching period and the design considerations and a control strategy are explained. Finally, the converter operation is verified by simulation and experimental results.

New Zero-Current-Transition (ZCT) Circuit Cell Without Additional Current Stress

  • Kim, C.E.;Park, E.S.;G.W. Moon
    • Journal of Power Electronics
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    • v.3 no.4
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    • pp.215-223
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    • 2003
  • In this paper, a new zero-current-transition (ZCT) circuit cell is proposed. The main switch is turned-off under the zero current and zero voltage condition, and there is no additional current stress and voltage stress in the main switch and the main diode, respectively. The auxiliary switch is turned-off under the zero voltage condition, and the main diode is turned-on under the zero voltage condition. The resonant current required to obtain the ZCT condition is relatively small and regenerated to the input voltage source. The operational principles of a boost converter integrated with the proposed ZCT circuit cell are analyzed and verified by the simulation and experimental results.

Evaluation of Correction Parameter for the Free-fall Grab Based Mn Nodule Abundance in the Southern Sector of the KODOS (KODOS 남쪽광구에서 자유낙하식 채취기로 채취된 망간단괴 부존률 평가를 위한 보정상수 검증)

  • Lee, Hyun-Bok;Ko, Young-Tak;Kim, Jong-Uk;Chi, Sang-Bum;Kim, Won-Nyon
    • Economic and Environmental Geology
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    • v.44 no.6
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    • pp.475-483
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    • 2011
  • Quantitative estimate of manganese nodules based on the operation of a free fall grab (FFG) needs to be corrected because of its less retrieval ability. Previously, the correction parameter of the nodule abundance collected by FFG was calculated based on the image analysis of the photos of bottom sediment in the northern sector of the nodule exploration area of Korea in the NE equatorial Pacific. However, nodules in the southern sector are commonly covered by sediment, which may prevent the use of the correction parameter estimated by photographic techniques. In this study, we attempted dual nodule sampling at the same location by different equipments (i.e. box corer (BC) and FFG) to examine the previous correction parameter of nodule abundance for FFG operation. During the exploration cruises in 2007 to 2009, Mn-nodules were collected from 40 stations both by BC and FFG in the southern sector. The correlation analysis between BC and FFG operations revealed that the BC collected nodules 1.43 times larger than FFG. Our result suggests that the correction parameter of 1.43 can be applied for collection of FFG data to estimate Mn-nodule distribution in the southern sector. The obtained parameter is similar to the previous parameter (1.42~1.45) calculated by the image analysis method, indicating an usefulness of new correction parameter suggested by this study.