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최남섭
- Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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- 2003.05a
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- pp.556-559
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- 2003
This paper presents a study on pull cord switch system which is employed in various industry for emergency stop of the equipments. In this paper, a new method for operation position detection of pull cord switch is suggested which is based on sensing operation position by detecting input resistance variation due to switching operation of pull cord switches with respective ohmic resisters. Moreover, this paper proposes a resistor circuit structure in order to improve recognition rates. Finally, this paper treats a system where such operating switches can be read by PLC.
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Seo, Sang-Hern;Lee, Chang-Sik
- Transactions of the Korean hydrogen and new energy society
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- v.20 no.4
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- pp.283-290
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- 2009
This study focuses on the performance characteristics of polymer electrolyte membrane fuel cell (PEMFC) using the AC impedance technique. The experiment was carried out to investigate the optimal operating conditions of PEMFC such as cell temperature, flow rate, humidified temperature and back-pressure. The fuel cell performance was analyzed by DC electronic-loader with constant voltage mode and expressed by voltage-current density. Additionally, AC impedance was measured to analysis of ohmic and activation loss and expressed by Nyquist plot. The results showed that the cell performance increased with increase of cell temperature, air flow rate, humidified temperature and backpressure. Also, the activation loss decreased as the increase of cell temperature, air flow rate, humidified temperature and backpressure.
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Kang, Min-Su;Han, Kyo-Yong
- The Transactions of the Korean Institute of Electrical Engineers C
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- v.51 no.11
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- pp.546-550
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- 2002
In this paper, Heterojunction phototransistors(HPT's) with an optically transparent ITO emitter contacts were fabricated. The ITO ohmic contacts were realized by employing thin imdium layer between the ITO and $n^+$-InP layers. The ITO contact was annealed at $250^{\circ}C$. The specific contact resistance of about $6.6{\times}10^{-4}{\Omega}cm^2$ was measured by use of the transmission line model (TLM). Heterojunction bipolar transistors (HBTs) having the same device layout were fabricated to compare with HPTs. The DC characteristics of the InP/InGaAs HPT showed the similar electrical characteristics of the HBT. Emitter contact resistance($R_E$) of about $6.4{\Omega}$ was extracted, which was very similar to that of the HBT. The optical characteristics of HPT's were generated by illuminating the device with light from $1.3{\mu}m$ light. It showed that HPT's can be controlled optically.
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