• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.69-70
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• 2007

Now the IEC flicker measuring algorithms and its flicker index of $P_{st}$ and $P_{lt}$ are accepted internationally as standards. But it is recently found that IEC flickermeter has a main drawback that it cannot afford to detect the fluctuating patterns of voltage envelope caused by interharmonics higher than 102Hz in the 60Hz power system. This is brought about by two components of IEC flicker measuring steps, squaring and low-pass filtering. This paper presents the innate defect of IEC flickermeter and proposes a modified measuring method considering the voltage flickers by subharmonics and interharmonics.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.655-659
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• 2005

The environment. of electric railway has, included both fast and slow load variation, which may occur in the office or maintenance factory or running electric train. This paper investigated flicker indices according to voltage fluctuations on three different situations; The base office in new subway in the daytime and night time, inside of electric train running in conventional subway. And also the variations of harmonic frequencies(2nd, 3rd, 5th) with rime were measured at the same time. Flicker index is a good tool for evaluating the voltage fluctuation quantitatively and show some relationship with even harmonic frequencies produced by the voltage fluctuation when the electric train is running on the railway.

• Journal of Electrical Engineering and Technology
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• v.1 no.2
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• pp.153-160
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• 2006

This paper presents a new compensating system, which consists of a shunt active filter and passive components for mitigating voltage and current disturbances arising from an Electric Arc Furnace (EAF). A novel control strategy is presented for the shunt active filter. An extended method based on instantaneous power theory in a rotating reference frame is developed for extraction of compensating signals. Since voltages at the point of common coupling contain low frequency interharmonics, conventional methods cannot be used for dc voltage regulation. Therefore, a new method is introduced for this purpose. The passive components limit the fast variations of load currents and mitigate voltage notching at the Point of Common Coupling (PCC). A three-phase electric arc furnace model is used to show power quality improvement through reactive power and harmonic compensation by a shunt active filter using the proposed control method. The system performance is investigated by simulation, which shows improvement in power quality indices such as flicker severity index.

• Safety and Health at Work
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• v.13 no.2
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• pp.148-154
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• 2022

Background: Bus driving is a mentally demanding activity that requires prolonged attention to ensure safety. The aim of the study was to assess mental fatigue caused by driving a public bus and to find a profile of workers at higher risk. Methods: We evaluated changes of critical flicker fusion (CFF) (index of central arousal) and heart rate variability (HRV) (index of autonomic balance) in a 6-hour driving shift on a real route, in 31 professional bus drivers, and we tested the influence of personal factors such as sleep quality, BMI, and age. Paired t-test was used to test differences of CFF and HRV between both initial and final phase of driving, while multiple linear regression tested the influence of personal variables on the indexes of mental fatigue. Results: Results showed that CFF significantly decreased after 6 hours of bus driving (41.91 Hz, sd 3.31 vs. 41.15 Hz, sd 3.15; p = 0.041), and heart rate significantly decreased in the final phase of driving, with respect to the initial phase (85 vs. 78 bpm, p = 0.027). Increasing age (beta = -0.729, p = 0.022), risk of obstructive sleep apnea syndrome (beta = -0.530, p = 0.04), and diurnal sleepiness (beta = -0.406, p = 0.017) showed a significant effect on influencing mental fatigue. Conclusion: Elderly drivers at higher risk of sleep disorders are more prone to mental fatigue, when exposed to driving activity. Monitoring indexes of central arousal and autonomic balance, coupled with the use of structured questionnaires can represent a useful strategy to detect profile of workers at higher risk of mental fatigue in such duty.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2176_2177
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• 2009

This paper describe the power quality measuring result of the inter-connected residental PV system. The power quality measuring for inter-connected residental PV system are important to verify their performance and effect of power distribution system with inter-connected residental PV system. Also, these power quality measuring and analysis are essential to improve electrical safety. In order to evaluate influence of power distribution system with inter-connected residental PV system, we measure and analyze power quality index such as power, voltage, current, harmonic, THD, flicker index, power factor and frequency using DEWE5000.

• International Journal of Internet, Broadcasting and Communication
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• v.9 no.2
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• pp.70-77
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• 2017

Where there are all the flowers, the songs of all kinds of insects and birds are put in, the sunshine and shadows flicker The forest through which the water sound flows is an optimum resting space. All living creatures in these spaces will awaken the five senses of humans and perhaps turn the sensibility index (EQ). The forest meditation in the forest, which can be an optimal shelter for the people who need it, needs to feel the reverence of nature, to refine emotions, to be a self-reflection, to have a mind to respect, Have an important meaning. In this paper, we tried to consider the cause of the influence of forest sounds on human hearing from the acoustical aspect. The type of sound source of forest was divided into four seasons of spring, summer, autumn, winter. And the change in the duration of the sound during the four seasons, so that the general characteristics of the sounds of the four seasons are as follows: It can be seen that the change in the ratio of sub-band energy is almost equal to the change in dB in frequency of the equal-light curve. To compare this phenomenon, the criterion for changing the sound duration of each forest is natural The main forms of the luminance curve, such as the change in the duration of the white signal in the sound, are determined by the minimum, maximum audible frequency and the most sensitive frequency band, and the auditory characteristics of the other three inflection points Determines the overall shape of the equal-light curve.