• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.50 no.8
• /
• pp.392-401
• /
• 2001

This paper presents the single-stage high power factor AC to DC converter operated in active-clamp mode. The proposed converter is added active-clamping circuit to boost-flyback single-stage power factor corrected power supply. The active-clamping circuit limits voltage spikes, recycles the energy trapped in the leakage inductance, and provides a mechanism for achieving soft switching of the electronic switches to reduce the switching loss. The auxiliary switch of active-clamping circuit uses the same control and driver circuit as the main switch to reduce the additional cost and size. To verify the performance of the proposed converter, a 100W converter has been designed. The proposed converter gives good power factor correction, low line current harmonic distortions, and tight output voltage regulation, as used unity power factor.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.45 no.2
• /
• pp.125-129
• /
• 2008

A low-voltage active CMOS inductor approach, which can improve the quality-factor(Q), is proposed in this paper. A low-voltage active inductor circuit topology with a feedback resistance is proposed, which can substantially improve its equivalent inductance and quality-factor(Q). This proposed low-voltage active inductor with a feedback resistance was simulated by ADS(Agilent) using 0.18um standard CMOS technology. Simulation showed that the designed active inductor had a maximum quality-factor(Q) of 3000 with a 1.5nH inductance at 4GHz

• Journal of the Korean Applied Science and Technology
• /
• v.38 no.6
• /
• pp.1616-1626
• /
• 2021

The purpose of this study was to investigate the relationship among perceived environmental factor, active aging and self-rated health for active senior golf participants. The collected data were analyzed using the SPSS 18.0 and AMOS 18.0 programs for Windows. Frequency analysis, confirmatory factor analysis, reliability analysis. After correlation analysis and structural equation model analysis were used. As a results derived through the research are as follows. First perceived environmental factor had a positive effect on active aging. Second, active aging had a positive effect on self-rated health. Third, perceived environmental factor had a positive effect on self-rated health. Fourth, active aging mediated the relationship between perceived environmental factor and self-rated health.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.4
• /
• pp.716-723
• /
• 2007

This paper suggests of a 3-phase 3-wire unified active power filter. The system is composed of a series active power filter and a parallel active power filter. The proposed series active power filter compensating unbalance source voltage and current harmonics of the parallel active power filter improves power factor. The proposed algorithm which improves for power factor and harmonic reduction are calculated by the performance function, and which compensates for the unbalanced source voltage is calculated based on the symmetrical component analysis. We composed a combined system of the series active power filter and parallel active power filter to confirm a validity of the proposed control methods. The effectiveness of the proposed algorithm is confirmed by the experiments.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.53 no.1
• /
• pp.24-29
• /
• 2004

A new low cost hybrid active filter for thyristor-controlled rectifier load is presented to overcome the high cost problem of the active or the other hybrid active filters. The proposed hybrid active filter which consists of tuned (5th and 7th harmonics) LC passive filters, power factor improvement(PFI) capacitor bank, and active filter compensates power factor as well as harmonic currents. Since most of harmonic currents are filtered by the passive filter and most of reactive power is compensated by the PFI capacitor bank, the power rating of active filter can be minimized, resulting in cost minimization of the proposed hybrid active filter. A 300kVA hybrid active filter system is implemented and tested using 1MVA thyristor rectifier load to verify the operation and performance.

• Proceedings of the KIPE Conference
• /
• 2011.07a
• /
• pp.444-446
• /
• 2011

A bidirectional dual active converter with the power factor control capability is proposed as a battery charger. The source side half-bridge acts as a PWM converter that maintains the unity power factor. The battery side half-bridge converter acts as a dual active bridge (DAB) together shares the same DC link voltage with PWM converter. The imbalance voltage phenomenon is eliminated by employing asymmetric duty cycle technique. Simulation results are included to verify theoretical analysis.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.55 no.5
• /
• pp.258-264
• /
• 2006

This paper presents an integrative control scheme for series-type active power filters combined with shunt passive filters not only to compensate for the source voltage unbalance and current harmonics but also to correct the power factor. To reduce the power capacity of the active filters, passive filters are connected in parallel. Diode rectifiers are replaced by the PWM converters in order to feed the real power back to the source. Power factor control is performed by changing the phase of the load voltage so that the phase of the source current coincides with that of the source voltage. The resultant voltage reference is the addition of the voltage component compensating for the source voltage unbalance and harmonic currents and the voltage component correcting the power factor. The validity of the proposed algorithm has been verified by experimental results.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.11
• /
• pp.2149-2154
• /
• 2009

Electric power quality in power transmission/distribution systems has considerably been deteriorated with the increase in the capacity of distributed generators (DGs). It is because inverters, connecting DGs to conventional power grids, tend to generate harmonic current and voltage. For harmonic mitigation, a large amount of research has been done on passive and active filters, which have been operating successfully in many countries. This paper, therefore, presents how to adopt the filters to an inverter-based DG, with considering a system consisting of both inverter-based DG and harmonic filters. In particular, this paper describes the simulation results using the PSCAD/EMTDC: firstly, the relationship between total harmonic distortion(THD) of current and output power of DG: secondly, the harmonic mitigation ability of passive and active filters. The system, furthermore, is obliged to satisfy the regulations made by Korean Electric Power Corporation(KEPCO). In the regulations, power factor should be maintained between 0.9 and 1 in a grid-connected mode. Thus, this paper suggests two methods for the system to control its power factor. First, the inverter of DG should control power factor rather than an active filter because it brings dramatic decrease in the capacity of the active filter. Second, DG should absorb reactive power only in the range of low output power in order to prevent useless capacity increase of the inverter. This method is expected to result in the variable power factor of the system according to its output power.

• Journal of the Korean Society of Safety
• /
• v.35 no.2
• /
• pp.55-60
• /
• 2020

The purpose of this study is to analyze the influence of the economic and workforce factors on the annual number of occupational accident fatalities occurring at the construction sites. The considered variables of the economic factor are the amount of economic losses caused by industrial accidents, the GDP, and the total monthly wage for each economically active population. And, the variables related to the workforce factor are the number of economically active population, the number of female economically active population, and the number of labor union members. The multiple regression analysis was conducted to determine the effect of two factors on the total number of occupational fatalities in the construction industry. The results show that GDP among considered variables in the economic factor had a statistically significant negative relationship with the number of the construction accident fatalities in the construction industry. Among variables related to the workforce factor, economically active population showed a statistically significant negative relationship with the number of the construction accident fatalities.

• Proceedings of the KIEE Conference
• /
• 1996.11a
• /
• pp.373-377
• /
• 1996

Recently, active power factor control for AC/DC converter has been required to replace for a conventional diode rectifier. A voltage type AC/DC converter is widely used to obtain higher regulated DC voltage than input voltage with a unity power factor and a sinusoidal line current. This paper describes several active power factor control method for AC/DC converter. The analysis of several active power factor control is given. The simulations for hysteresis control, peak current control. constant frequency control and average current mode control are represented and compared.