• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.1999-2001
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• 1997

The main two drawbacks of the Sin91e Stage PFC (SS-PFC) converters employing a DCM Boost PFC cell are relatively high voltage stress on the bulk capacitor and the input current harmonic distortion. The high voltage stress on bulk capacitor makes the SS-PFC converter impractical in a universal input application and the input current harmonic distortion lowers power factor. In this paper a selective variable frequency control that reduces the voltage stress on the bulk capacitor and the input current harmonic distortion is proposed. Computer simulation results of the proposed control method are presented.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.3
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• pp.161-166
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• 2011

In this paper, for analysing the major factors giving the effect to the quality of HD level video on the multicasting service, we tried this test experiment on the College school network similar to the real service network environment. We measure the video quality distortion on the multicasting HD level video according to generating and increasing the broadcasting traffic on the situation that apply the QoS technique to the test network and not apply the QoS technique and then find out the threshold value of network factors giving the effect to the video quality distortion on the multicasting HD level video service. This paper can be used for guaranteeing the constant video quality and reducing the video quality distortion on the multicasting HD level video service.

• Journal of the Society of Disaster Information
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• v.17 no.1
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• pp.184-193
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• 2021

Purpose: In this study, since the operation principle of the CCFL Exit light is the same as that of general lighting equipment, the characteristics of the CCFL Exit light were analyzed by deriving test items that can affect the characteristics of the light source from the KS standard, which is the standard for lamp ballast performance certification of general lighting equipment. Method: The samples used in the experiment were performed on products of two manufacturers for each size, such as large, medium, and small, and the test items were power factor, crest factor, and current harmonic distortion. Result: As a result of the experiment, the power factor showed a value between 0.4 and 0.6 in all samples, which was smaller than the 0.9 value set by KS. The crest factor ranged from 3.6 to 3.7 for large, 4.4 to 4.7 for medium, and 3.5 to 3.7 for small. It showed a value more than two times higher than the KS standard of 1.7. Current total harmonic distortion ranged from 81% to 110%, and considering that the KS standard was less than 20%, it could be confirmed that all samples had a value significantly exceeding the KS standard. Conclusion: The crest factor and current total harmonic distortion may affect the temperature rise of the light source and the burnout of the device. When developing an exit light, if this item is developed within the scope of the KS standard, the quality improvement and maintenance of the exit light will be greatly improved.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.6D
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• pp.663-673
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• 2009

Driver's perceived curve radius is different from actual curve radius at curve sections. This is called visual distortion. It has effect on operation speed according to driver's perception and finally bad effect on safety at curve sections. At present, however, there is no research on quantitatively analysis of visual distortion and no criteria for curve section design considering the visual distortion. Therefore, this study focus on finding degree of visual distortion and suggesting design criteria by visual distortion analysis. The process of this study is as below; First, a calculaiton model of perceived curve radius was developed by survey using computer simulation. In this model, a dependent variable is perceived curve radius and an independent variable is geometric factors. Second, degree of visual distortion was calculated from ratio of perceived curve radius to actual curve radius. Finally, design criteria were suggested through influencing factor analysis of visual distortion at curve sections.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.1
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• pp.64-70
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• 2010

This paper presents how to decide on tuning factor(${\delta}$) and quality factor(Q) values in design of single-tuned passive harmonic filters. Tuning factor(${\delta}$) and quality factor(Q) values have to consider before decision on circuit parameters of passive filters. A Study on these two value has not been scarcely performed and only experienced values has been used in passive harmonic filter design by far. As a experienced value, in cases of 5th and 7th filter, tuning factor(${\delta}$) is about 0.94 and 0.96 respectively and quality factor(Q) is, in all cases of, 50. If Single-tuned passive harmonic filter will be off-tuned, performance of filter will be decreased steeply and occur to parallel resonance between system reactance and filter capacitance. Therefore During the operation, In order not to off-tuning, Filter must be tuned at former order than actual tuning order. This is the same that total impedance of filter must have a reactive impedance. In this paper, Tuning factor(${\delta}$) is decided via example of real system and using the bode-plot and then performance of filters confirmed by filter current absorbtion rate. And Quality factor(Q) decided using the bode plot in example system and then performance of filters confirmed by filter current absorbtion rate also, which makes a calculated filter parameters to satisfy IEEE-519 distortion limits. Finally, Performance of the designed passive harmonic filter using the tuning factor(${\delta}$) and quality factor(Q) values, decided in this paper is verified by experiment and shows that 5th, 7th, 9th, 11th and 13th current harmonic distortions are decreased within IEEE-519 distortion limits, respectively.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.3
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• pp.25-33
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• 1999

In this paper, the method of reducing hanmnics and correcting of power factor in single PWM converter associated with diode rectifier and boost converter is studied. In the general diode rectifier there are sorre problems that discontinuous current of reducing power factor and including distortion of hanmnics at the input current affects other sources. To solve the problems of performance degradation due to pulse wavefonn in the input current, the ac-dc converter in which the hanmnic distortion in the input current is reduced using a third-hanmnic-injected PWM is proposed. A lower power loss of switching and easy configuration of circuit are obtained by adopting discontinuous current mode. Simulation and experimental results of ac-dc converter with 5[kHz] switching frequency are presented and correction of power factor and reduction of total hanmnic distortion was established.lished.

• The Research Journal of the Costume Culture
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• v.22 no.5
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• pp.848-861
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• 2014

This research was designed to conduct research to apprehend fashion brand's mobile SNS characteristics in depth and the related consumer psychology and behaviors such as brand attachment and brand loyalty. The fashion brand's mobile SNS characteristics were differentiated from the web-based fashion brand's SNS. This study targeted women in their 20s using mobile Facebook and mobile Twitter, and residing in Seoul or Gyeonggi province. Total 412 observations were collected through online survey. The major findings of the study were as follows. First, as the characteristics of fashion brand's mobile SNS, ease of fashion data storage, fashion recentness, fashion usefulness, and fashion accessibility were extracted. As the factors of the flow, time distortion/focused attention and playfulness were extracted. Second, the fashion recentness and fashion usefulness showed positive influence to time distortion/focused attention factor in the flow. All four fashion brand's mobile SNS characteristics showed positive influence to playfulness factor in the flow. Third, time distortion/focused attention factor and playfulness factor both showed positive influence to brand attachment and brand loyalty from using fashion brand's mobile SNS. Fourth, brand attachment had positive influence to brand loyalty from using fashion brand's mobile SNS. Based on the above results, this study provided practical ways to develop effective mobile SNS marketing strategies in fashion brand. Also, this study demonstrated feasible future contents and necessary improvement for fashion brand's mobile SNS, which holds marketing implications.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.7
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• pp.121-127
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• 2016

We propose a algorithm to calculate power factor of fundamental waveform in an environment where the voltage and current have been distorted by harmonics. In the proposed power factor computation algorithm, voltage and current are converted to rotating DQ reference frame, and power factor is calculated from active power and reactive power. We compare the proposed method with the conventional power factor measurement method as mathematically. In a condition that voltage and current are distorted by harmonics, the proposed method accurately measure the power factor of fundamental wave, and it is confirmed by simulation using MATLAB. If the proposed power factor measurement method is applied to an automatic power factor control system, a power factor compensation performance can be maximized in harmonic distortion environment. As a result, it is possible to reduce electricity prices, reduce line loss, increase load capacity, ensure the transmission margin capacity, and reduce the amount of power generation.

• Journal of Electrical Engineering and information Science
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• v.1 no.2
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• pp.52-57
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• 1996

Detection of arcing high impedance faults has been a perplexing in the power distribution protection. Transient analysis of distribution disturbances for fault discrimination from other normal events is important for a secure protection of the power system. A simple parameter of wave form distortion quantification is used to analyze the behaviors of arcing faults and normal distribution disturbances. Theoretical perspectives of the transients were studied and actual disturbances were examined. From this investigation, a discrimination guideline based on the revised crest factor is developed. The discrimination method has a high potential to enhance the reliability and security for the distribution system protection.

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.2072-2074
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• 1997

A new low-cost high power factor correction circuit for electronic ballasts is proposed. The proposed circuit provides good power factor correction, low current harmonic distortion and cost-effectiveness. The prototype meets the IEC555-2 requirements satisfactorily with nearly unity power factor.