• Title/Summary/Keyword: Flickers

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A Study on the Harmonic and Flicker Effects of SVC in Electric Arc Furnace Loads (전기로 부하에서 SVC의 고조파 및 플리커 효과에 관한 연구)

  • Kim, Kyung-Chul;Choi, Hyoung-Bumb;Oh, Jung-Suk
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.10
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    • pp.150-158
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    • 2007
  • Large steel industries have time-varying nonlinear loads including electric arc furnaces. These nonlinear loads generate harmonic currents and create distortions on the sinusoidal voltage of the power system. Flicker can be defined as the effect produced on the human visual perception by a changing emission of light lamps subjected to magnitude fluctuations of their supply voltage. The main objective of the static var compensator(SVC) is to maintain the rms voltage at the point of common coupling within the limit. In this paper, harmonic and flicker mitigation studies with and without the SVC are investigated and are evaluated by the IEC 61000-3-6 and IEC 61000-3-7.

Vibration Characteristics of Lean Premixed Flame Anchored by a Hydrogen Pilot Flame in a Tube (파일롯 화엄에 의해 고정된 관내 예혼합 화염의 진동 특성)

  • Guahk, Young-Tae;Oh, Kwang-Chul;Shin, Hyun-Dong
    • 한국연소학회:학술대회논문집
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    • 2004.06a
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    • pp.42-48
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    • 2004
  • Lean laminar premixed propane and methane flames which were anchored by a hydrogen-pilot flame in a tube were investigated experimentally. The flame shapes were observed by varying mean velocity from 10cm/s to 140cm/s and equivalence ratio from 0.45 to 0.8. In this study, behaviors of flames are divided into five regions such as tail-out, flash-back, flickering, stable and vibrating flames with respect to the mean velocity and the equivalence ratio. Although the flames are unstable in both the flickering and the vibrating region, they have different characteristics such as the frequency, sound generation and creation process of flame curvature. The flickering region exists near the flammability limit and the flame flickers in a frequency of about 10Hz. When flame front is bended, the propane flame front is straightened and the methane flame front is bended more by thermo-diffusive instability. In the vibrating region, the flame vibrates emitting audible sound in a frequency of about 100Hz. In the boundary of vibrating region, the vibration of flame changes between two modes such as single frequency vibration and dual frequency vibration. Increase and decrease of vibration in each mode are determined by thermo-acoustic instability.

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A study of the Implementation of Adaptive De-interlacing Algorithm with Improved Horizontal and Vertical Edges (수평 및 수직 윤곽선을 개선한 적응 주사선 보간 알고리즘 및 구현에 관한 연구)

  • Kwon, Yong-Jae;Park, No-Kyung;Moon, Dai-Tchul
    • Journal of IKEEE
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    • v.2 no.2 s.3
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    • pp.225-232
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    • 1998
  • Currently NTSC, PAL, and SECOM are widely used for TV broadcasting systems. In Korea, NTSC has been used to reduce transmission bandwidth and broadband flickers using the Interlaced scanning method. Image data in the Interlaced scanning method require De-interlacing compensation for PC-based multimedia applications. The existing compensation algorithms such as ZOI, FOI, and ELA provieds simple computations and effective image compensation while the PSNR is low and horizontal and vertical edges are hardly detected. In this paper, the ADI(Adaptive De-Interlacing) algorithm that can increase PSNR and detect horizontal and vertical edges is proposed and a hardware system is implemented using three ACTEL 1020B FPGA chips. The system consists of the algorithm part implemented using two FPGAs and the memory control part implemented using rest one. Also the system operation is investigated for real time processing.

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A Comparative Study on the Quantitative Analysis of the Flicker Phenomena in the Amorphous-Silicon and Poly-Silicon TFT-LCDs (비정질 및 다결정 실리콘 TFT-LCD에서의 플리커(flicker) 현상 비교 분석 연구)

  • Son, Myung-Sik;Song, Min-Soo;Yoo, Keon-Ho;Jang, Jin
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.40 no.1
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    • pp.20-28
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    • 2003
  • In this paper, we present results of the comparative analysis of the flicker phenomena in the poly-Si TFT-LCD and a-Si:H TFT-LCD arrays for the development and manufacturing of wide-area and high-quality TFT-LCD displays. We used four different types of TFTs; a-Si:H TFT, excimer laser annealed (ELA) poly-Si TFT, silicide mediated crystallization (SMC) poly-Si TFT, and counter-doped lateral body terminal (LBT), poly-Si TFT. We defined the electrical quantity of the flicker so that we could compare the flickers quantitatively for four different 40" UXGA TFT-LCDs. We identify three factors contributing to the flicker, such as charging time, kickback voltage and leakage current, and analyze how much each of three factors give rise to the flincker in the different TFT-LCD arrays. In addition, we suggest and show that, in the case of the poly-Si TFT-LCD arrays, the low-level (minimum) gate voltages should be carefully chosen to minimize the flicker because of their larger leakage currents compared with a-Si TFT-LCD arrays.

A study of Agricultural fatigue shoes - A comparative study of heat load by shoe type - (농작업화에 관한 연구 - 신발종류에 따른 열적 부담 비교연구 -)

  • 이경숙;최정화
    • Korean Journal of Rural Living Science
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    • v.7 no.2
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    • pp.99-108
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    • 1996
  • This study has intended to suggest fundamental data to develope and choose appropriate shoes for upland farming in order to prevent health deterioration of women workers and improve work effectiveness and reduce fatigue by wearing appropriate shoes. During 1995. 4. 28 - 5. 10, Fifty women workers in hot pepper farming were observed and major shoe types, which were rubber shoes, walking shoes, slippers, and rubber boots, were selected for the study. During 1995. 10. 9 - 31, two subjects were tested by wearing those shoes in the laboratory where the temperature was 24$\pm$1$^{\circ}C$ and relative humidity 50$\pm$5%RH. And the temperature & humidity on sole and in the shoes, the rectal temperature, skin temperature, blood pressure, pulse, lactate concentration of blood, Flickers' value and subjective sensation were measured. The results were as follows : 1. 84% of women workers mentioned that they need shoes improvement and the order of most frequent shoe types to be worn was rubber shoes, walking shoes, slippers, rubber boots. 2. The rate of women who were unsatisfied with shoes for upland farming is 38 percentages. The reason of unsatisfaction was that feet were in a sweat and alien substances were let into shoes. 3. The temperature & humidity on sole were the lowest in rubber boots during experiment(p<0.01). 4. The relative humidity in the shoes was the highest in rubber boots by 90% and the lowest in walking shoes by 72% during rest And the humidity in slippers and walking shoes were significantly low in experiment(p<0.001). 5. Rubber boots showed the highest rise in rectal temperature by 0.2$^{\circ}C$ showing increase of core temperature (p<0.05). 6. The mean skin temperature during experiment was highest in rubber boots by 33.8$^{\circ}C$(p<0.001).

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The Effects of Seaman's on Board Service Career on Physical Fitness Characteristics and Mental Fatigue (선박근무자의 승선경력이 정신피로 및 체력특성에 미치는 영향)

  • 하해동;김재호
    • Journal of the Korean Institute of Navigation
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    • v.25 no.4
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    • pp.347-360
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    • 2001
  • The purpose of this study is to find out the subjective and objective fatigue level and the characteristics of seamen's physical strength with the service period on board, to have a new understanding of the vocation, and to explore a physical exercising program for the seamen. The questionnaire survey for the seamen who had been in service on the ocean going vessels was conducted and the results are fumed out as the followings. Total number of seamen who had answered the questionnaire was 64 persons and the distribution status of service period group was identified as 16 persons for each of 4 groups; the group was classified as the group of less than 5 years, 5 - 10 years, 10 - 15 years, and more than 15 years. 1. Working conditions Working hours in a week was identified as 44-56 hours(45.3%) and the number of 45.3% of the seamen answered the working hours in week is more than 56 hours. The seamen of 25.0% are unsatisfied or very unsatisfied with their vocation. The seamen of 65.6% are smoking, and 45.3% of them drink. The seamen of 44.,3% drink once or more in a week. And the seamen of 67.2% do not take any exercise in a week. 2. Contribution to the seamen's fatigue and subjective symptom The most contributive factor to the seamen's fatigue was identified as the short of sleeping(21.5%), overwork(19.2%), poor working conditions (18.6%), and the friction in human relations also becomes one the contribution to the fatigue(14.0%). The subjective symptom by fatigue was identified as the feeling of languid, sleepy and tiredness of eyes. 3. Characteristics of the seamen's physical strength and Interrelations The grip strength and back strength of the seamen whose service period is less than 5 years were measured as 40.44kg and 127.8kg. The sit ups in the group of service period less than 5 years was measured as 36.84 times, and the vertical jump for the seamen in this group was measured as 46.55cm. The closed-eyes foot balance was measured as 33.64 seconds in the group of service period between 5 and 10 years, and side-step was measured as 35.31 times in the group of service period less than 5 years. The standing trunk flexion was measured as 10.54cm for the seamen whose service period is between 10-15 years, and the trunk extension was measured as 50.70cm for the seamen whose service period is less than 5 years. And the step test of the seamen whose service period is between 10-15 years was measured as 54.44 numbers, and the number of flickers of the seamen whose service period is less than 5 years was measured as 32.94.

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Design and Implementation of Response type of Flickering Green Signal System using Beacon Message (비콘메세지를 이용한 반응형 녹색점멸 신호시스템 설계 및 구현)

  • An, Hyo-In;Mun, Hyung-Jin;Kim, Chang-Geun
    • Journal of Digital Convergence
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    • v.14 no.11
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    • pp.241-247
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    • 2016
  • As a domestic traffic control signal system, either the system with which a traffic signal turns into green at regular intervals or the system with which an amber or a red signal flickers on local roads without heavy traffic at midnight has been utilized. However, when the former system is used for roads with light traffic at midnight, delays and congestion can be incurred. Besides, in case of the latter signal system, the risk of vehicle crash is high. This study proposes a response type of flickering green signal system that rearranges signal system after analyzing beacon messages including sensor data. The proposed system, on a trunk road or a branch road at midnight, makes the signal keep flickering in green; When a vehicle enters the range of RSE, the transfer coverage, it transmits beacon messages regularly and Agent System analyzes the messages and alters the signal. It is a system by which vehicles move following the altered signal system, which will not only ensure smooth flow but also prevent vehicles from crashing on a road with light traffic. As a result of a simulation, traffic throughput and the average waiting time displayed 10 to 30 percent better improvement than existing signal systems, in terms of performance.