• 제목/요약/키워드: 안정파고

검색결과 76건 처리시간 0.026초

A Novel Method to Reduce Crest Factor of Electronic Ballast for Fluorescent Lamps Using Pulse Frequency Modulation (펄스 주파수 변조 기법을 이용한 형광등 안정기의 파고율 저감 기법)

  • Song, Joo-Ho;Lee, Dong-Yun;Song, Joong-Ho;Choi, Ju-Yeop;Choy, Ick;Lim, Myo-Taeg
    • The Transactions of the Korean Institute of Power Electronics
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    • 제5권3호
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    • pp.291-299
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    • 2000
  • 형광등의 수명은 형광등 안정기의 시동 시나리오와 형광등 전류의 파고율에 영향을 받는다. 본 논문에서는 특히 파고율을 주로 다루며, 파고율을 줄이기 위한 새로운 방법을 제시하고자 한다. 제안하고자 하는 방법은 펄스 주파수 변조기법(Pulse Frequency Modulation, PFM)을 이용하며, PFC(Power Factor Correction)가 만드는 50% 벨리필 전압 파형을 PFM 제어 신호로 사용한다. 본 논문에서는 제안하는 PFM 제어 기법으로 파고율을 1.7 이하로 낮출 수 있음을 모의 실험과 실험을 통해 확인하여, 제안한 기법의 타당성을 검증한다.

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The development of power supply of High-Repetition Pulsed $CO_2$ Laser using SMPS (SMPS 방식의 고반복 펄스형 $CO_2$ 레이저의 전원장치 개발)

  • 이동훈;정현주;김도완;김희제
    • Proceedings of the Optical Society of Korea Conference
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    • 한국광학회 2000년도 제11회 정기총회 및 00년 동계학술발표회 논문집
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    • pp.316-317
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    • 2000
  • 펄스형 $CO_2$레이저는 적외선 영역인 10.6 $mu extrm{m}$ 파장의 매우 안정된 고출력 펄스를 방출시킬 수 있으므로 산업용, 군사용, 의료용, 각종 물리.화학의 기초 연구용 등의 광범위한 응용 분야에서 각광을 받고 있다. 특히 금속의 정밀절단, 심용접에서는 수 십 Hz로부터 수 kHz의 펄스 출력이 필요하다. 펄스방식은 Normal Pulse와 Super Pulse로 크게 나눌 수 있다. Normal Pulse의 경우에는 Pulse의 파고치가 연속파의 파고치와 동일하기 때문에 펄스시의 평균 출력은 연속파의 경우보다 낮다. Super Pulse의 경우에는 Pulse 파고치를 연속파의 파고치보다 훨씬 높게 할 수 있으므로 평균 출력은 낮지만 첨두 출력이 높아서 유리 등 세라믹 재료의 가공에 널리 사용된다$^{(1)}$ (중략)

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Experimental and Numerical Analyses for Irregular Wave Breaking over a Shelf Region (Shelf 지형에서 불규칙파의 쇄파실험 및 수치해석)

  • Lee, Jong-In;Kim, Young-Taek
    • Journal of Korea Water Resources Association
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    • 제46권5호
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    • pp.491-504
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    • 2013
  • In this study, wave breakings over a shelf region are investigated under irregular wave conditions through laboratory experiments in a wave flume. Numerical simulations based on the Boussinesq-type equations are also conducted. The characteristics of breaking waves such as significant wave height, crest and trough heights, the mean water level and the stable wave height are obtained by analyzing laboratory measurements in detail. Obtained results are compared with those of the Boussinesq-type equations model. A very reasonable agreements is observed. The broken waves over a horizontal bottom asymptotically approach a stable wave height($H_{stable}$). In this study, the relative stable wave height is found as $H_{stable}/h{\fallingdotseq}0.56$ for irregular wave.

Rolling Dynamic Response Analysis of Mobile Harbor Crane by Sea State 3 Wave Excitation (해상상태 3의 파고에 따른 모바일 하버 크레인의 롤링 동응답 해석)

  • Han, Ki-Chul;Hwang, Soon-Wook;Choi, Eun-Ho;Cho, Jin-Rae;Lim, O-Kaung
    • Journal of the Computational Structural Engineering Institute of Korea
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    • 제23권5호
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    • pp.493-499
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    • 2010
  • In the sea-floating logistics port called mobile harbor a crane system with the different structure from the conventional above-ground container crane is installed. And, the dynamic stability of whole mobile harbor by the wave excitation is definitely affected by the crane positioned at the top. This paper is concerned with the dynamic rolling analysis of the mobile harbor subject to sea state 3 wave excitation, for which two-step analysis procedure composed of theoretical and numerical approaches is employed. First, the rigid rolling of mobile harbor is obtained according to the linear wave theory. And then, the dynamic rolling response of the flexible crane system caused by the rolling excitation of mobile harbor is analyzed by finite element analysis. The coupled interaction effect between the sea wave and the mobile harbor is taken into consideration by the added mass technique.

A Study on function of Artificial Reef by Using Geotexile Tube (토목섬유를 활용한 인공리프의 기능에 관한 연구)

  • Shin, Moon-Seup;Ahn, Kyung-Soo;Shin, Eun-Chul
    • Journal of Korea Water Resources Association
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    • 제36권4호
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    • pp.623-631
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    • 2003
  • A large scale hydrological laboratory model tests for the geotextile tube were conducted to investigate the stability of geotextile tube and the capability of breakwater with variations of significant wave height, percentage of soil filling, and the water level above geotextile tube. The sliding displacement of geotextile tube is measured to check the stability of geotextile tube for given the various significant wane heights. The marked mash was laid out at the bottom of water channel to measure the displacement of geotextile tube. The bench mark was furnished in the upper part of water channel and the initial location was marked every 10cm interval to measure the displacement of geotextile tube. The wane transmit ratios are analyzed with the variations of soil filling of tube and of the top crown height wave above the geotextile tube in order to study the performance of brekwater before and after the installation of geotextile tube.

A Study of Stability Analysis for Exit Light (유도등의 안정성 해석에 관한 연구)

  • Jung, Jong-Jin;SaKong, Seong-Ho
    • Journal of the Korean Society of Hazard Mitigation
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    • 제8권4호
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    • pp.81-85
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    • 2008
  • In this study, Standards of Lighting Appliance and Standard of Model Approval and Inspection Technology for EXIT LIGHT are compared so as to analyze stability of a exit light which is fire product. Test items, which are not included in Standard of Model approval and Inspection Technology for EXIT LIGHT, are deduced from aforementioned comparison and analysis. Also the derived test items are experimented with a exit light. For a power factor correction, a power factor correction circuit is designed and power factor, crest factor, asymmetry ratio, luminance variation are analyzed. In order to show the validity of designed circuit, current waveform and voltage waveform are measured.

Wave Prediction in a Harbour using Deep Learning with Offshore Data (딥러닝을 이용한 외해 해양기상자료로부터의 항내파고 예측)

  • Lee, Geun Se;Jeong, Dong Hyeon;Moon, Yong Ho;Park, Won Kyung;Chae, Jang Won
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • 제33권6호
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    • pp.367-373
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    • 2021
  • In this study, deep learning model was set up to predict the wave heights inside a harbour. Various machine learning techniques were applied to the model in consideration of the transformation characteristics of offshore waves while propagating into the harbour. Pohang New Port was selected for model application, which had a serious problem of unloading due to swell and has lots of available wave data. Wave height, wave period, and wave direction at offshore sites and wave heights inside the harbour were used for the model input and output, respectively, and then the model was trained using deep learning method. By considering the correlation between the time series wave data of offshore and inside the harbour, the data set was separated into prevailing wave directions as a pre-processing method. As a result, It was confirmed that accuracy and stability of the model prediction are considerably increased.

Influence of Water Depth on Climate Change Impacts on Caisson Sliding of Vertical Breakwater (직립방파제의 케이슨 활동에 미치는 기후변화영향에 대한 수심의 효과)

  • Kim, Seung-Woo;Kim, So-Yeon;Suh, Kyung-Duck
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • 제24권3호
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    • pp.179-188
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    • 2012
  • Performance analyses of vertical breakwaters were conducted for fictitiously designed breakwaters for various water depths to analyze the influence of climate change on the structures. The performance-based design method considering sea level rise and wave height increase due to climate change was used for the performance analysis. One of the problems of the performance-based design method is the large calculation time of wave transformation. To overcome this problem, the SWAN model combined with artificial neural network was used. The significant wave height and principal wave direction at the breakwater site are quickly calculated by using a trained neural network with inputs of deepwater significant wave height and principal wave direction, and tidal level. In general, structural stability becomes low due to climate change impacts, but the trend of stability is different depending on water depth. Outside surf zone, the influence of wave height increase becomes more significant, while that of sea level rise becomes negligible, as water depth increases. Inside surf zone, the influence of both wave height increase and sea level rise diminishes as water depth decreases, but the influence of wave height increase is greater than that of sea level rise. Reinforcement and maintenance policies for vertical breakwaters should be established with consideration of these results.

Development of an ADC System for Measurements of Radioactive Coincidence Coefficients (방사능 동시계수의 측정을 위한 ADC시스템 개발)

  • 오용선
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 한국해양정보통신학회 1998년도 춘계종합학술대회
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    • pp.389-393
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    • 1998
  • 방사성 핵종의 인위적 방사능 측정과 환경방사능의 측정에 있어서, 발생된 펄스의 에너지와 발생 상대시간을 동시에 측정하여 계수함으로써, 채널분해능과 시간분해능 및 처리속도를 향상시킬 수 있는 ADC 시스템을 개발하였다. 다양한 크기를 갖는 입력펄스의 파고와 관계없이 일정한 불감시간(deadtime)을 갖는 방식으로 시간보정 과정을 필요로 하지 않으며, 측정된 파고와 상대적 불감시간은 동시에 계수되어 방사능 분석을 위한 자료로 제공된다. 본 연구는, 기존에 측정효율을 감소시키는 주요 원인이 되었던 불감시간 보정 과정을 배제하고 전체 스펙트로스 코피(spectroscopy)의 정확도 및 안정도를 유지할 수 있는 변환체계를 개발하며, 특히 측정 환경에 따라 다양하게 적용할 수 있는 불감시간 측정방식을 제공하는 것이다.

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Reliability Analysis and Evaluation of Partial Safety Factors of Breakwater Armor stones Considering Correlation between Wave Height and Wave Steepness (파고와 파형경사의 상관성을 고려한 피복석의 신뢰성 해석 및 부분안전계수 산정)

  • Kim, Seung-Woo;Suh, Kyung-Duck
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • 제20권3호
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    • pp.300-309
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    • 2008
  • The partial safety factors of armor stones have been calculated on the assumption that all random variables are independent one another. However, wave height and wave steepness are not independent in the van der Meer's formula of armor stones but they are correlated. In the present study, we calculated the partial safety factors considering the correlation and compared them with those of other researchers who did not consider the correlation. The correlation between wave height and steepness is closely related to the variability of wave period. As the variability of wave period decreases, the correlation between wave height and steepness becomes strong, and hence the calculation results with and without consideration of the correlation show more difference. Therefore, the correlation should be taken into account in the calculation of partial safety factors in the area where the variability of wave period is small.