• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1999-2004
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• 2011

This research aims to develop polymer composites which can be used for PEMFC bipolar plate by injection molding process. Considering the moldability and stiffness, we used LCP(Liquid crystal polymer) as base resin. In order to improve electrical conductivity and mechanical properties, we chose carbon black, and both synthetic graphite and expanded graphite. The composites with different recipe are prepared for injection molding of PEMFC bipolar plate and CAE(Computer Aided Engineering) analysis was performed to predict melt flow and fiber orientation We did successfully fabricate the ASTM specimens by injection molding, and measure the electrical conductivity of the samples by using four point probe device. We measured mechanical properties such as flexural strength, flexural modulus and Izod impact strength. Conclusively, the electrical conductivity increased with increasing additive concentration, but both flexural strength and Izod impact strength decreased due to the brittle nature of carbon-based additives.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.10
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• pp.41-50
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• 1993

This paper describes the fabrication process and electrical characteristics of PSA (Polysilicon Self-Align) bipolar transistors with a thin base width of 1100.angs.. To realize this shallow junction depth, one-step rapid thermal annealing(RTA) technology has been applied instead of conventional furnace annealing process. It has been shown that the series resistances and parasitic capacitances are significantly reduced in the device with emitter area of 1${\times}4{\mu}m^{2}$. The switching speed of 2.4ns/gate was obtained by measuring the minimum propagation delay time in the I$^{2}$L ring oscillator with 31 stages.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.239-242
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• 1999

In this paper, we report the process/device design of high-speed, high-voltage SOI smart power IC for mobile communication system, high-speed HDD system and the electronic control system of automobiles. The high voltage LDMOS with 70V breakdown voltage under 0.8${\mu}{\textrm}{m}$ design rule, the high voltage bipolar with 40V breakdown voltage for analog signal processing, the high speed bipolar with cut-off frequency over 20㎓ and LDD NMOS for high density were proposed and simulated on a single chip by the simulator DIOS and DESSIS. And we extracted the process/device parameters of the simulated devices.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.83.2-83.2
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• 2011

The emergence of a magnetic flux tube (flux emergence) is a process of transporting magnetic field from the solar interior to the atmosphere. This process naturally produces bipolar structure at the surface, in which emerging field lines simply connect opposite polarities, while observations suggest that the surface distribution of magnetic field is more complicated than a simple bipole. This study is aimed at solving this apparent mismatch between the model and observations, showing how the surface distribution changes from a simple bipolar distribution to a quadrupolar-like one, where a half-turn rotation of the polarity inversion line plays an important role. We explain the physical reason of this half-turn rotation and also discuss a possible configuration of filament magnetic field in terms of the quadrupolar-like structure formed via flux emergence.

• Membrane Journal
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• v.13 no.3
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• pp.143-153
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• 2003

The effects of bipolar interface formed on the surface of cation-exchange membrane on water splitting phenomena were investigated. Results showed that the formation of immobilized bipolar interface resulted in significant water splitting during electrodialysis. In particular, the immobilized bipolar interface was easily created on the cation-exchange membrane surface in the electrodialytic systems where multivalent cations served as an electrolyte. Multivalent cations with low solubility product resulted in violent water splitting because they were easily precipitated on the membrane surface in hydroxide form. Therefore, the bipolar interface consisting of H- and OH-affinity groups were formed on the membrane-solution interface. Apparently, water splitting was largely activated with the help of strong electric fields generated between the metal hydroxide layer and fixed charge groups on the membrane surface. Likewise, the accumulation of large molecular counter ions on the membrane surface led to the formation of a fixed bipolar structure that could cause significant water splitting in the over-limiting current region. Therefore, the prevention of the immobilization of bipolar interface on the membrane surface is very essential in improving the process efficiency in a high-current operation.

• Membrane Journal
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• v.32 no.5
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• pp.357-365
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• 2022

Recently, as the demand for secondary batteries for electric vehicles has rapidly increased, the efficient production of lithium compounds is attracting great attention. Bipolar membrane electrodialysis (BPED) is known as an eco-friendly, economical, and efficient electrochemical lithium compound production process. Since the efficiency of the BPED depends on the performance of the bipolar membrane (BPM), the selection of the BPM is very important. In this study, the characteristics of BPMs suitable for the BPED for electrochemical LiOH production were derived by comparative analyses of BP-1E (Astom) and FBM (Fumatech), which are the most widely used commercial BPMs in the world. Through systematical evaluation, it was confirmed that reducing membrane ion transfer resistance and co-ion leakage among the characteristics of BPM is the most important, and BP-1E has better performance than FBM in this respect.

• Composites Research
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• v.36 no.6
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• pp.422-428
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• 2023

The electrical contact resistance between the bipolar plate (BP) and the carbon felt electrode (CFE), which are in contact by the stack clamping pressure, has a great impact on the stack efficiency because of the relatively low clamping pressure of the vanadium redox flow battery (VRFB) stack. In this study, a polyethylene (PE) composite-CFE hybrid bipolar plate structure is developed through a local heat welding process to reduce such contact resistance and improve cell performance. The PE matrix of the carbon fiber composite BP is locally melted to create a direct contact structure between the carbon fibers of CFE and the carbon fibers of BP, thereby reducing the electrical contact resistance. Area specific resistance (ASR) and gas permeability are measured to evaluate the performance of the PE composite-CFE hybrid bipolar plate. In addition, an acid aging test is performed to measure stack reliability. Finally, a VFRB unit cell charge/discharge test is performed to compare and analyze the performance of the developed PE composite-CFE hybrid BP and the conventional BP.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.239-240
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• 2011

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.6
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• pp.752-759
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• 2007

For an accurate measurement of aerosol particle size distribution using a differential mobility analyser (DMA), a new calculation process, capable of predicting the masses for the various kinds of water cluster ions generated from a bipolar ionizer, was prepared by improving the previous process. The masses for the 5 kinds of positive and negative water cluster ions produced from a SMAC ionizer were predicted by the improved calculation process. The aerosol particle charging ratios calculated by applying the predicted ion masses to particle charging equations were in good accordance with the experimentally measured ones, indicating that the improved calculation process are more reasonable than the previous one in a mass prediction of bipolar water cluster ions.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.717-722
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• 2004

A design was done, and all characteristic of photodetectr of the web pattern type which a standard process of the Bipolar which Si PIN structure was used in this paper, and was used for the current amplifier design was used, and high-speed, was used as receiving optcal area of high altitude, and the module which had a low dark current characteristic was implemented with one chip with a base. Important area decreases an area of Ie at the time of this in order to consider an electrical characteristic and economy than the existing receiving IC, and performance of a product and confidence are got done in incense. First of all, the receiving IC which a spec, pattern of a wafer to he satisfied with the following electrical optical characteristic that produced receiving IC of 5V and structure are determined, and did one-chip is made. On the other hand, the time when AR layer of double is $Si_{3}N_{4}/SiO_{2}=1500/1800$ has an optical reflectivity of less than $10{\%}$ on an incidence optical wavelength of 660 ,and, in case of photo detector which reverse voltage made with 1.8V runs in 1.65V, an error about a change of thickness is very the thickness that can be improved surely. And, as for the optical current characteristic, about 5 times increases had the optical current with 274nA in 55nA when Pc was -27dBm. A BJT process is used, and receiving IC running electricity suitable for low voltage and an optical characteristic in minimum 1.8V with a base with two phases is made with one chip. IC of low voltage operates in 1.8V and 3.0V at the same time, and optical link receiving IC is going to be implemented