• Title/Summary/Keyword: High step-up

Search Result 699, Processing Time 0.027 seconds

Analysis of the Isolated Boost Converter Using Self-Driven Switch (자기구동 스위치를 이용한 절연된 부스트 변환기의 해석)

  • Hong, Soon-Chan;Chae, Soo-Yong;Chung, Dae-Taek;Kim, Hee-Sun
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.24 no.6
    • /
    • pp.89-98
    • /
    • 2010
  • Isolated boost converter is desirable in the dc/dc converter applications where isolation is required and extremely high step up is needed. Transformer used to step up low input voltage into high output voltage must satisfy the volt-sec balance condition. Conventional isolated boost converter is controlled with conducting intervals overlapping. In this case, there is a problem that control circuit is complicated. In this paper, it is proposed and analyzed the isolated boost converter which set up a reset winding for the volt-sec balance of transformer and can construct the control circuit simple by using a self-driven switch. Finally, the validity of the theoretical analyses for the proposed converter is verified by both simulations and experiments on the 10[W] class isolated boost converter.

Path Analysis and SERVQUAL for Knowledge Quality Improvement (지식정보 품질향상을 위한 경로 분석 및 SERVQUAL)

  • 박정훈;손소영
    • Journal of Korean Society for Quality Management
    • /
    • v.28 no.3
    • /
    • pp.145-154
    • /
    • 2000
  • Effective management of knowledge is essential to keep up with demands of this challenging information age. The first step for this kind of management would be to define indicators to evaluate the quality of knowledge. In this paper, we use five latent variables (intrinsic quality, representational quality, ease of use of quality, maintainable quality, usage of quality) as basis for a preliminary path analysis for knowledge management. Preliminary study results showed that high intrinsic quality does not necessarily guarantee high frequency of use. A modified questionnaire is made and is used for SERVQUAL. The result of SERVQUAL shows that customers are not relatively happy about both intrinsic quality and its ease of use. Additional path analyses are done for both expected and observed quality indicators. The path model based on the expectation indicated that the presentation method of knowledge would induce its easy maintenance while that based on observation did not back up the same phenomenon.

  • PDF

High Efficient AC-PDP Energy Recovery Circuit Employing Step-Up Faculty (승압 기능을 가지는 AC-PDP 구동을 위한 고효율 에너지 회수 회로에 대한 연구)

  • Kang, Feel-Soon;Park, You-Hwan;Park, Sung-Jun;Kim, Cheul-U
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2002.05a
    • /
    • pp.1-5
    • /
    • 2002
  • The sustain driver for AC plasma display panel should provide alternating high voltage pulses to ignite plasma and recover the energy discharged from the intrinsic capacitance between the scanning and sustaining electrodes inside the panel. In this paper, an efficient sustain circuit employing boost-up function is proposed to achieve a faster rise-time in order to be suitable to widely used the address display period separated (ADS) driving method. The proposed circuit improves the recovery efficiency, regardless of the variation of the panel capacitance. The principle of operation, features, and simulated results are illustrated and verified on a 7.5-inch diagonal panel at 200 [kHz] operating frequency based on experimental prototype.

  • PDF

CORE DESIGN CONCEPTS FOR HIGH PERFORMANCE LIGHT WATER REACTORS

  • Schulenberg, T.;Starflinger, J.
    • Nuclear Engineering and Technology
    • /
    • v.39 no.4
    • /
    • pp.249-256
    • /
    • 2007
  • Light water reactors operated under supercritical pressure conditions have been selected as one of the promising future reactor concepts to be studied by the Generation IV International Forum. Whereas the steam cycle of such reactors can be derived from modem fossil fired power plants, the reactor itself, and in particular the reactor core, still need to be developed. Different core design concepts shall be described here to outline the strategy. A first option for near future applications is a pressurized water reactor with $380^{\circ}C$ core exit temperature, having a closed primary loop and achieving 2% pts. higher net efficiency and 24% higher specific turbine power than latest pressurized water reactors. More efficiency and turbine power can be gained from core exit temperatures around $500^{\circ}C$, which require a multi step heat up process in the core with intermediate coolant mixing, achieving up to 44% net efficiency. The paper summarizes different core and assembly design approaches which have been studied recently for such High Performance Light Water Reactors.

Low Resolution Rate Face Recognition Based on Multi-scale CNN

  • Wang, Ji-Yuan;Lee, Eung-Joo
    • Journal of Korea Multimedia Society
    • /
    • v.21 no.12
    • /
    • pp.1467-1472
    • /
    • 2018
  • For the problem that the face image of surveillance video cannot be accurately identified due to the low resolution, this paper proposes a low resolution face recognition solution based on convolutional neural network model. Convolutional Neural Networks (CNN) model for multi-scale input The CNN model for multi-scale input is an improvement over the existing "two-step method" in which low-resolution images are up-sampled using a simple bi-cubic interpolation method. Then, the up sampled image and the high-resolution image are mixed as a model training sample. The CNN model learns the common feature space of the high- and low-resolution images, and then measures the feature similarity through the cosine distance. Finally, the recognition result is given. The experiments on the CMU PIE and Extended Yale B datasets show that the accuracy of the model is better than other comparison methods. Compared with the CMDA_BGE algorithm with the highest recognition rate, the accuracy rate is 2.5%~9.9%.

Upconversion Mechanisms in $Tm^{3+}$-doped Glasses under 800 nm Excitation (800nm 파장 여기관에 의한 $Tm^{3+}$첨가 유리내 상향 전이 현상 기구)

  • Jeong, Hoon;Chung, Woon-Jin;Heo, Jong
    • Journal of the Korean Ceramic Society
    • /
    • v.37 no.2
    • /
    • pp.111-116
    • /
    • 2000
  • 700nm red emission(3F3longrightarrow3H6) in Tm3+ ion with 800 nm(3H6longrightarrow3H4) excitation via upconversion process has been reported only in host materials which have low phonon energies such as halide crystals. However, we observed 700nm and 480nm(1G4longrightarrow3H6) upconverted emission with 800nm excitation in several oxide glasses which has never reported. With spectroscopic analyses and lifetime measurements of each nergy level of Tm3+ ion doped in various oxide glasses, following mechanisms are suggested. For red upconversion, upconversion mechanism changed with Tm3+ concentration. While direct excitation up to 3F3 level via anti-Stokes excitation was dominated at low concentration, two-step excitation via 3H6longrightarrow3H4 and 3F4longrightarrow3F3 transitions was dominated at high concentration. For blue upconversion, two step excitation mechanism up to 1G4 level was suggested as follows : electrons are exciated up to 3H5 with direct excitation with pumping light up to 3H4 followed by multiphonon relaxation, and then additional reabsorption of pumping light excites electrons up to 1G4.

  • PDF

Development of Normal-Opposite Rotational Durability Test Equipment for Large Sized Planetary Gear Box (대형 유성기어박스의 정역회전 내구성시험장치 개발에 관한 연구)

  • Lee, Yong-Bum;Kim, Kwang-Min
    • Journal of the Korean Society of Manufacturing Technology Engineers
    • /
    • v.21 no.2
    • /
    • pp.305-310
    • /
    • 2012
  • Planetary gear box is a power transmitter having very high gear ratio in compact volume. The planetary step-down gear box converts high speed and low torque into low speed and high torque, which is widely used in constructional and industrial machinery field. And, the planetary step-up gear box does vice versa working, which is used as main gear box of large sized wind mill system. The large sized planetary gear box must be performed the normal-opposite rotation test as a its durability test for achieving the reliability. The large sized planetary gear box is composed by triple gear trains of sun gear, carrier, and ring gear. If input power is supplied into one of them and the other is fixed, and then another becomes the output part. In this paper, we designed a new test equipment which can do rapid normal and opposite rotational change with only small displacement by supplying test power using the above rotation (driving) characteristics and hydraulic cylinder and link, and also compared and analyzed with existing method through various experiments.

A Study on the Feeding System of Centerless Grinder for Machining the Ferrule (페룰가공용 무심연삭기 이송계 개발)

  • 박천홍;황주호;조순주
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2002.10a
    • /
    • pp.65-69
    • /
    • 2002
  • In order to practicalize high precision centerless grinder for machining the ferrule, its feeding system is designed and tested. For satisfying the desired diametric tolerance and cylindricity of the ferrule, the feeding system is designed to have relatively high axial stiffness of 600 N/$\mu\textrm{m}$, high angular motion accuracy of 0.5 arcsec/mm in yaw direction and minimum resolution of 0.05 $\mu\textrm{m}$. A prototype of feeding system is built up with hydrostatic guideway and ballscrew. A linear scale with 0.05 $\mu\textrm{m}$ of resolution is used for position feedback. Experimental results show that the feeding system has the infinity of axial stiffness within the range of 1000 N and 0.3 arcsec/mm of yawing error. Also the feeding system shows obvious step response against 0.05 $\mu\textrm{m}$/step command without the lost motion or backlash. Although the vertical stiffness is reduced to 440 N/$\mu\textrm{m}$ by the elastic deformation of rail, it is good enough to use for machining the ferrule. From above, it is confirmed that the feeding system is applicable to centerless grinder for machining the ferrule.

  • PDF

Bidirectional Tapped-inductor Boost-Flyback Converter (비절연형 양방향 탭인덕터 부스트 플라이백 컨버터)

  • Kim, Hyun-Woo;Jeon, Young-Tae;Park, Joung-Hu;Jeon, Hee-Jong
    • The Transactions of the Korean Institute of Power Electronics
    • /
    • v.20 no.5
    • /
    • pp.395-401
    • /
    • 2015
  • This paper proposes a new bidirectional DC-DC converter with high efficiency. The proposed converter is composed of a flyback and a tapped-inductor boost converter to satisfy extreme operating conditions with low cost. The outputs are connected in series to achieve a high-voltage step-up. In the reverse direction, the proposed converter has an extreme step-down voltage. In this study, the proposed converter was employed with a 100 W hardware prototype. To design the controller, a small-signal transfer function of the proposed converter is derived. For PV power conditioning systems, a maximum power point tracking method is applied with perturb and observe method. To verify the operation of the bidirectional power flow, the current controller is applied. All of the controllers are employed with a digital signal processor.

Improvement of Measuring Capacity of the DC High-voltage Divider for a National High-voltage Standard (국가 고전압 표준용 직류고전압 분압기의 측정능력 향상)

  • Lee, Sang-Hwa;Jang, Seok-Myeong;Choi, Jang-Young
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.63 no.11
    • /
    • pp.1622-1625
    • /
    • 2014
  • The main measurement uncertainty factors in DC high-voltage dividers for a national high-voltage standard are the measurement uncertainty of low-voltage arm and the stability of a high-voltage supply. In this study, the uncertainties by the two factors are greatly improved. As a result the measurement uncertainty for the DC high-voltage divider is reduced from $16{\times}10^{-6}(k=2)$ to $8{\times}10^{-6}(k=2)$ which is at international level.