• 제목/요약/키워드: series-parallel

검색결과 970건 처리시간 0.021초

Evaluation of thermal conductivity in REBCO coated conductor

  • Yong-Ju, Hong;Sehwan, In;Hyobong, Kim;Hankil, Yeom
    • 한국초전도ㆍ저온공학회논문지
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    • 제24권4호
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    • pp.78-83
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    • 2022
  • REBCO coated conductors are widely used for HTS power application, high magnetic field magnet application, and etc. A thermal stability of the REBCO conductor is essential for the operation of HTS-based device, and thermal conductivities of the conductor are relevant parameters for modeling cryogenic heat transfer. REBCO conductors consist of a REBCO layer, copper layers for electrical stabilization and a hastelloy substrate. At cryogenic temperature, thermal conductivity of copper and silver strongly depend on the purity of the material and the intensity of the magnetic field. In this study, thermal conductivities of the laminated composite structure of REBCO conductor are evaluated by using the thermal network model and the multidimensional heat conduction analysis. As a result, the thermal network model is applicable to REBCO conductors configured in series or parallel alone and multidimensional heat conduction analysis is necessary for complex cases of series and parallel configuration.

Sabotage of Intruder Alarm System Loop

  • Karel Burda
    • International Journal of Computer Science & Network Security
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    • 제23권7호
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    • pp.23-31
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    • 2023
  • This article discusses the sabotage of loops of intruder alarm systems. Although loop alarm systems are now gradually being replaced by digital alarm systems, they are still significantly present in practice. This paper describes two experimentally verified techniques for sabotaging balanced loops. The first technique is based on the jump replacement of the balancing resistor by a fake resistor. The second technique is based on inserting a series-parallel combination of two rheostats into the loop. By alternately changing the resistance of these rheostats, a state is reached where the balancing resistor is shorted by the parallel rheostat and replaced by the series rheostat. Sabotage devices for both attacks are technically simple and inexpensive, so they can be made and used by an amateur. Owners of loop alarm systems should become find out about this threat.

Photovoltaic Properties of Tandem Structure Consisting of Quantum Dot Solar cell and Small Molecule Organic Solar cell

  • Jang, Jinwoong;Choi, Geunpyo;Yim, Sanggyu
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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    • pp.249.2-249.2
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    • 2015
  • Connecting two or more sub-cells is a simple and effective way of improving power conversion efficiency (PCE) of solar cells, and the theoretical efficiency of this tandem cell is known to reach 85~88% of the sum of the sub-cell's efficiencies. There are two ways of connecting sub-cells in the tandem structure, i.e. parallel and series connection. The parallel connection can increase the short circuit current (Jsc) and the series connection can increase the open circuit voltage (Voc). Although various tandem structures have been studied, the full use of incident light and optimization of cell efficiency is still limited. In this work, we designed series tandem solar cells consisting of lead sulfide (PbS) quantum dots/zinc oxide-based QDSC and zinc phthalocyanine (ZnPc)/C60-based small molecule OSCs. It is expected that the loss of the incident light is minimized because the absorption range of the PbS quantum dots and ZnPc is significantly different, and the Voc increases according to the Kirchhoff's law.

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그림자 효과에 의한 염료감응형 태양전지의 특성연구 (A Characteristic Study on the Dye-Sensitized Solar Cell by the Shadow Effect)

  • 김희제;이정기;이경준;프라바카르;신동설;채원용
    • 전기학회논문지
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    • 제59권1호
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    • pp.144-151
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    • 2010
  • The shadowing effects lead to the serious power losses of the PV module. The shadowing effects are caused by several factors such as leafs, dust, antenna and clouds. The dye-sensitized solar cells are more economical than the conventional silicon solar cell that's why the dye-sensitized solar cells are recently focused on. We carried out research on the efficiency of the dye-sensitized solar cell depending on the level of shadow changing the formula of the circuit. The research on the efficiency of the large dye-sensitized solar cell depending on the level of shadow focused on commercialization was carried out. As the results, it is known that the series and parallel connection method is the best choice for the least losses of PV module assemblies. It is especially known that one more series connection is the best choice for the least losses about shadowing effects and current losses in the series and parallel connection.

DGS를 이용한 주파수 가변 DL-CRLH 전송선로 (A Frequency Adjustable Double Lorentz CRLH Transmission Line using DGS)

  • 임종식;이재훈;이준;정용채;한상민;안달
    • 전기학회논문지
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    • 제59권8호
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    • pp.1429-1435
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    • 2010
  • In this paper, a double lorentz composite right left handed(DL-CRLH) transmission line is designed using defected ground structure (DGS) and varactor diodes. Previously, the diode has been adopted only selectively for one of parallel or series resonators, and the balanced frequency as well as triple band frequencies were fixed. However in the proposed DL-CRLH transmission line, the balanced frequency, where the resonant frequencies of the series-connected parallel resonator and shunt-connected series resonator are the same, is adjustable. In addition, the triple band frequencies are controlled, too. The measured balanced frequency varies between 3.42~4.8GHz according to the controlled bias voltage. Under the same bias condition for the balanced frequency, the adjusted frequencies are 2.22~2.77GHz, 3.7~5.2GHz, 7.32~8.23GHz, 3.42~4.8GHz, and 4.44~5.92GHz for the conditions that ${\beta}d=+0.5{\pi}$, $-0.5{\pi}$, 2nd $+0.5{\pi}$, ${\omega}_{\infty}$, and ${\omega}_o$, respectively.

Evaluation Methods and Design for Bioartificial Liver Based on Perfusion Model

  • Park Yueng Guen;Ryu Hwa-Won
    • Biotechnology and Bioprocess Engineering:BBE
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    • 제10권1호
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    • pp.9-15
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    • 2005
  • A bioartificial liver (BAL) is a medical device entrapping living hepatocytes or immortalized cells derived from hepatocytes. Many efforts have already been made to maintain the functions of the hepatocytes in a BAL device over a long term. However, there is still some uncertainty as to their efficacy. and their limitations are unclear. Therefore, it is important to quantitatively evaluate the metabolic functions of a BAL. In previous studies on in vitro BAL devices, two test methods, an initial bolus loading and constant-rate infusion plus initial bolus loading, were theoretically carried out to obtain physiologic data on drugs. However, in the current study, the same two methods were used as a perfusion model and derived the same clearance characterized by an interrelationship between the perfusate flow rate and intrinsic clearance. The interrelationship indicated that the CL increased with an increasing perfusate flow rate and approached its maximum value, i.e. intrinsic clearance. In addition, to set up an in vivo BAL system, the toxic plateau levels in the BAL system were calculated for both series and parallel circuit models. The series model had a lower plateau level than the parellel model. The difference in the toxic plateau levels between the parallel and series models increased with an increasing number of BAL cartridges.

Resonance Characteristics Analysis of Grid-connected Inverter Systems based on Sensitivity Theory

  • Wu, Jian;Han, Wanqin;Chen, Tao;Zhao, Jiaqi;Li, Binbin;Xu, Dianguo
    • Journal of Power Electronics
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    • 제18권3호
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    • pp.746-756
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    • 2018
  • Harmonic resonance exists in grid-connected inverter systems. In order to determine the network components that contribute to harmonic resonance and the composition of the resonant circuit, sensitivity theory is applied to the resonance characteristic analysis. Based on the modal analysis, the theory of sensitivity is applied to derive a formula for determining the sensitivities of each network component parameter under a resonance circumstance that reflects the participation of the network component. The solving formula is derived for both parallel harmonic resonance and series harmonic resonance. This formula is adopted to a 4-node grid-connected test system. The analysis results reveal that for a certain frequency, the participation of parallel resonance and series resonance are not the same. Finally, experimental results demonstrate that the solving formula for sensitivity is feasible for grid-connected systems.

A Novel Parallel Viterbi Decoding Scheme for NoC-Based Software-Defined Radio System

  • Wang, Jian;Li, Yubai;Li, Huan
    • ETRI Journal
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    • 제35권5호
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    • pp.767-774
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    • 2013
  • In this paper, a novel parallel Viterbi decoding scheme is proposed to decrease the decoding latency and power consumption for the software-defined radio (SDR) system. It implements a divide-and-conquer approach by first dividing a block into a series of subblocks, then performing independent Viterbi decoding for each subsequence, and finally merging the surviving subpaths into the final path. Moreover, a network-on-chip-based SDR platform is used to evaluate the performance of the proposed parallel Viterbi decoding scheme. The experiment results show that our scheme can speed up the Viterbi decoding process without increasing the BER, and it performs better than the current state-of-the-art methods.

자속구속형 한류기의 직병렬조합에 따른 전류제한특성 (Current Limiting Characteristics of Flux-lock Type Superconducting Fault Current Limiter Using YBCO Films by Serial and Parallel Combinations)

  • 박형민;조용선;이주형;정병익;최효상;최명호
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2007년도 추계학술대회 논문집 전력기술부문
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    • pp.87-88
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    • 2007
  • We investigated the current limiting characteristics of flux-lock type superconducting fault current limiter using YBCO films University, Gwangju health college. The flux-lock type SFCL consisted of the transformer with a primary winding and a secondary winding connected in parallel, and the superconducting element was connected with secondary winding in series or parallel. Serial and parallel connections of superconducting elements are necessary for the increase of voltage and current capacities when we intend to apply the flux-lock type SFCL.

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순환-병렬형 아나로그-디지틀 변환기 (A Cyclic-Parallel Analog-to-Digital Converter)

  • 정원섭;김홍배;곽계달;박광민;손상희
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(II)
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    • pp.1166-1169
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    • 1987
  • A new analog-la-digital structure. called cyclic-parallel analog-to-digital(A/D) converter, has been developed for video applications. It consists of a M-bit parallel A/D converter, a digital-to-analog(D/A) converter, a differencing amplifier with gain of $2^M$ and two sample-and-hold circuits. In this structure, the input signal is circulated around the circuits K times, thereby converted into a MK-bit digital word. The proposed converter retains speed advantages of conventional series-parallel converters, with half reduced circuit components.

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