• Title/Summary/Keyword: ON/OFF Time

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Study on a Program for Automatic Control of on/off Switch on Modem (MODEM의 자동제어기 & 프로그램에 관한 연구)

  • Han Sang-Do
    • Journal of the military operations research society of Korea
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    • v.17 no.2
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    • pp.123-134
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    • 1991
  • one of the problems the users of DPS-6/45 used to face in the course of having access to work stations was that a telephone call has to be made manually every time to have receiver's modem on or off, and naturally it meant the waste of manpower as well as of time. A program has been worked out to automatically operate and control. utilizing the system clock within the main computer (DPS-6/45), the on/off switch on the modems. It has resulted in; 1) promotion in operability of the main computer, DPS-6/45 2) prevention of unnecessary telephone calls 3) curtailment of expenditure and manpower

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High-Power-Factor Boost Rectifier with a Passive Lossless Snubber (무손실 수동스너버를 갖는 고역율 부스트 정류기)

  • 김만고
    • Journal of Advanced Marine Engineering and Technology
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    • v.22 no.5
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    • pp.617-625
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    • 1998
  • A passive energy recovery snubber for high-power-factor boost rectifier, in which the main switch is implemented with a MOSFET, is described in terms of the equivalent circuits that are operational during turn-on and turn-off sequences. These equivalent circuits are analyzed so that the overshoot voltage across the main switch, the snubber current, and the turn-off transition time can be predicted analytically. From these results, the normalized overshoot voltage is reduced to 1 as $_W2T_on$ varies from zero to $\pi$/2, and then it is fIxed at 1 for $_W2T_on$> $\pi$/2. The peak snubber inductor current is directly proportional to the input current. The turn-offtransition time wltoffvaries from 0 to 2.57, depending on $_W2T_on$. The main switch combined with proposed snubber can be turned on with zero current and turned off at limited voltage stress. The high-power-factor boost rectifier with proposed snubber is implemented, and the experimental results are presented to confirm the validity of proposed snubber.

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Study of Blurring Free TFT-LCD Using Short Persistance Cold Cathode Fluorescent Lamp in Blinking Backlight Driving (단잔광 냉음극관을 이용한 잔상없는 TFT-LCD에 관한 연구)

  • Choi, Dae-Seub;Sin, Ho-Chul
    • Journal of Satellite, Information and Communications
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    • v.7 no.3
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    • pp.145-148
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    • 2012
  • In applying LCD to TV application, one of the most significant factors to be improved is image sticking on the moving picture. LCD is different from CRT in the sense that it's continuous passive device, which holds images in entire frame period, while impulse type device generate image in very short time. To reduce image sticking problem related to hold typedisplay mode, we made an experiment to drive TN-LCD like CRT. We made articulate images by turn on-off backlight, and we realized the ratio of Back Light on-off time by counting between on time and off time for video signal input during 1 frame (16.7ms). Conventional CCFL (cold cathode fluorescent lamp) cannot follow fast on-off speed, so we evaluated new fluorescent substances of light source to improve residual light characteristic of CCFL. We realized articulate image generation similar to CRT by CCFL blinking drive and TN-LCD overdriving. As a result, reduced image sticking phenomenon was validated by naked eye and response time measurement.

A Novel Zero-Crossing Compensation Scheme for Fixed Off-Time Controlled High Power Factor AC-DC LED Drivers

  • Chang, Changyuan;Sun, Hailong;Zhu, Wenwen;Chen, Yao;Wang, Chenhao
    • Journal of Power Electronics
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    • v.16 no.5
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    • pp.1661-1668
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    • 2016
  • A fixed off-time controlled high power factor ac-dc LED driver is proposed in this paper, which employs a novel zero-crossing-compensation (ZCC) circuit based on a fixed off-time controlled scheme. Due to the parasitic parameters of the system, the practical waveforms have a dead region. By detecting the zero-crossing boundary, the proposed ZCC circuit compensates the control signal VCOMP within the dead region, and is invalid above this region. With further optimization of the parameters KR and Kτ of the ZCC circuit, the dead zone can be eliminated and lower THD is achieved. Finally, the chip is implemented in HHNEC 0.5μm 5V/40V HVCMOS process, and a prototype circuit, delivering 7~12W of power to several 3-W LED loads, is tested under AC input voltage ranging from 85V to 265V. The test results indicate that the average total harmonic distortion (THD) of the entire system is approximately 10%, with a minimum of 5.5%, and that the power factor is above 0.955, with a maximum of 0.999.

Factors Contributing to Winning in Ice Hockey: Analysis of 2017 Ice Hockey World Championship (2017 International Ice Hockey Federation World Championship의 승리 결정요인 분석)

  • Lee, Jusung;Kim, Hyeyoung;Kim, Chaeeun;Pathak, Prabhat;Moon, Jeheon
    • 한국체육학회지인문사회과학편
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    • v.57 no.4
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    • pp.387-394
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    • 2018
  • The purpose of this study is to provide information regarding the strategies by identifying the main variables that determines the winning team based on the records of all games of the 2017 IIHF World Championship Top league. 64 matches were analyzed for the study. 6 variables were analyzed which included ratio of saves, shots on goal, penalties in minutes, time for power play, power play goals, and face off wins. Logistic regression analysis (LRA), multiple regression analysis (MRA), and principal component analysis (PCA) were implemented to examine the relationship between win and loss. In case of LRA, shots on goal (p<.001), face-off wins (p<.001) had significantly positive relation to winning of game whereas, penalties in minutes (p<.01) and time on power play (p<.01) had significantly negative. Using MRA, win percentage was calculated which had significant positive correlation to ratio of saves (p<.01) and face-off wins (p<.001) whereas, a significant negative with penalties in minutes (p<.001). For PCA, the winning team consisted of penalty, attack, and defense factors whereas, losing teams consisted only the attack and defense factors.

The study on ON-LINE and OFF-LINE systems of electronic image editing by time-code adressing method (전자 영상 편집에 있어서 time-code adressing 방식에 의한 ON-LINE, OFF-LINE system에 대한 연구)

  • BongJoKim
    • Journal of the Korean Graphic Arts Communication Society
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    • v.13 no.1
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    • pp.93-104
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    • 1995
  • Liquid crystal-polymer composite(LCPC) films promising new materials for both projection displays and vision product. LCPC films consist of a continous liquid crystal phase embedded in a three- dimensional network of polymer matrix. The liquid crystal in these LC phases can be elecrtrically switched giving rise to an opaque scattering off-stats and a transparent, non-scatting on- stats. In this work. a premixture is composed of LC, UV-curable monomer and photonitiator. LCPC films are formed by photopolymerization induced phase separation from this premixture. In conclusion, structure and electro-optical properties of LCPC films strongly depends on the selection of monomer, LC content and curing rate.

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A Study on Thermal Heating Control Performance of Automatic Thermostatic Valves in Floor Radiant Heating System (바닥난방 시스템의 열환경 개선을 위한 제어방안 연구)

  • Song, Jae-Yeob;Ahn, Byung-Cheon;Kim, Kyung-Chul;Jang, Sa-Yun
    • Proceedings of the SAREK Conference
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    • 2009.06a
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    • pp.973-978
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    • 2009
  • In this study, the thermal environment characteristics of On-Off control and thermal difference proportional control method in floor radiant heating system were researched by computer simulation. For the analysis of unsteady heat transfer phenomena in household, the method of using electrical equivalent R-C circuit is applied, and radiation heat transfer between panel, ceiling and walls in household is calculated by enclosure analysis method. The parametric study on two control methods, conventional on-off control and temperature error based time control(T.E.B.T.C.) method, are performed to compare thermal heating control performances, respectively.

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Study on changes in electrical and switching characteristics of NPT-IGBT devices by fast neutron irradiation

  • Hani Baek;Byung Gun Park;Chaeho Shin;Gwang Min Sun
    • Nuclear Engineering and Technology
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    • v.55 no.9
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    • pp.3334-3341
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    • 2023
  • We studied the irradiation effects of fast neutron generated by a 30 MeV cyclotron on the electrical and switching characteristics of NPT-IGBT devices. Fast neutron fluence ranges from 2.7 × 109 to 1.82 × 1013 n/cm2. Electrical characteristics of the IGBT device such as I-V, forward voltage drop and additionally switching characteristics of turn-on and -off were measured. As the neutron fluence increased, the device's threshold voltage decreased, the forward voltage drop increased significantly, and the turn-on and turn-off time became faster. In particular, the delay time of turn-on switching was improved by about 35% to a maximum of about 39.68 ns, and that of turn-off switching was also reduced by about 40%-84.89 ns, showing a faster switching.

Improvement of Lift-off Tests via Field Evaluation of Residual Load in Ground Anchor (현장 잔존긴장력 평가를 통한 리프트오프 시험 방법 개선)

  • Song, minkwon;Park, Seong-yeol;Lee, Sangrae;Cho, Wanjei
    • Journal of the Korean Geotechnical Society
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    • v.35 no.5
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    • pp.43-51
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    • 2019
  • At present, the ground anchor method is commonly applied to securing the slope stability in Korea. The ground anchor is reported to decrease in tensile load due to aging and environmental influences with time such as corrosion, relaxation, creep and so on. In Korea, the lift-off test is performed for the periodic inspection or cases when the symptoms of deterioration on anchors and the residual tensile load of the anchors is checked. However, the current lift-off test standard (MOLIT, 2010) is not fully specified in details. In this study, the factors affecting the lift-off test were investigated based on the previous research and foreign standards and lift-off tests were performed with consideration for the loading and unloading cycle, load increment method, and tensioning tendon method. Based on the results, this paper proposes improved testing and evaluation procedures of the lift-off test considering the workability and time limits in the field.

Determination of Optimal Turn-off Angle for SRM Converter Using Self-Tuning Method (SRM 컨버터에서 자기동조 방식에 의한 턴오프 각의 결정)

  • 장도현;문진영
    • The Transactions of the Korean Institute of Power Electronics
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    • v.3 no.4
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    • pp.418-425
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    • 1998
  • In this paper. determination method of turn-off angle in the SRM drives is proposed to maintain the high torque at a any turn-on angle, which is realized by using selHuning control method, During the sampling time. a number of P pulses from encoder are checked by using one-chip microprocessor. and compared with pre-checked a number of pulses A After calculating difference between two data, the turn-off angle moves forward or backward direction by the self-tuning m method, As repeating such process, the optimal turn-off angle is determined and the maximum torque is maintained T Though experiments, it is observed that motor speed is almost maintained if turn-off angle is adjusted automatically by s selHuning method when turn-ηn angle is changed.

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