• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.8
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• pp.10-21
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• 1999

This paper describes a 12bit CMOS current cell matrix D/A converter which shows a conversion rate of 65MHz and a power supply of 3.3V. Designed D/A converter utilizes current cell matrix structure with good monotonicity characteristic and fast settling time, and it is implemented by using the tree structure bias circuit, the symmetrical routing method with ground line and the cascode current switch to reduce the errors of the conventional D/A converter caused by a threshold voltage mismatch of current cells and a voltage drop of the ground line. The designed D/A converter was implemented with a $0.6{\mu}m$ CMOS n-well technology. The measured data shows a settling time of 20ns, a conversion rate of 50 MHz and a power dissipation of 35.6mW with a single power supply of 3.3V. The experimental SNR, DNL, and INL of the D/A converter is measured to be 55dB, ${\pm}0.5LSB$, and ${\pm}2LSB$, respectively.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.4
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• pp.364-371
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• 2005

Fuel cell systems(FCS) have a financial and environmental advantage by providing electricity at a high efficiency and useful heat. For use in a residence, a polymer electrolyte fuel cell system(PEFCS) with a battery pack and a hot water storage tank has been modelled and simulated. The system is operated without connection to grid line. Its electric conversion efficiency and heat recovery performance are highly dependent on operation strategies and also on the seasonal thermal and electric load pattern. The output of the fuel cell is controlled stepwise as a function of the state of the battery and/or the storage water tank. In this study various operation strategies for cogeneration fuel cell systems are investigated. Average fuel saving rates at different seasons are calculated to find proper load management strategy. The scheme can be used to determine the optimal operating strategies of PEFCS for residential and building applications.

• Korean Journal of Materials Research
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• v.27 no.2
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• pp.94-99
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• 2017

Dinickel-silicide $(Ni_2Si)/glass$ was employed as a counter electrode for a dye-sensitized solar cell (DSSC) device. $Ni_2Si$ was formed by rapid thermal annealing (RTA) at $700^{\circ}C$ for 15 seconds of a 50 nm-Ni/50 nm-Si/glass structure. For comparison, $Ni_2Si$ on quartz was also prepared through conventional electric furnace annealing (CEA) at $800^{\circ}C$ for 30 minutes. XRD, XPS, and EDS line scanning of TEM were used to confirm the formation of $Ni_2Si$. TEM and CV were employed to confirm the microstructure and catalytic activity. Photovoltaic properties were examined using a solar simulator and potentiostat. XRD, XPS, and EDS line scanning results showed that both CEA and RTA successfully led to tne formation of nano $thick-Ni_2Si$ phase. The catalytic activity of $CEA-Ni_2Si$ and $RTA-Ni_2Si$ with respect to Pt were 68 % and 56 %. Energy conversion efficiencies (ECEs) of DSSCs with $CEA-Ni_2Si$ and $RTA-Ni_2Si$catalysts were 3.66 % and 3.16 %, respectively. Our results imply that nano-thick $Ni_2Si$ may be used to replace Pt as a reduction catalytic layer for a DSSCs. Moreover, we show that nano-thick $Ni_2Si$ can be made available on a low-cost glass substrate via the RTA process.

• The Korean Journal of Food And Nutrition
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• v.27 no.4
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• pp.725-731
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• 2014

This study aims to find the correlation the low-molecule fucoidan for cancer prevention with an accelerated formation of cotinine. In the presence of fucoidan, a nicotine to cotinine coversion was studied in established assay, direct mixture method and Hep-G2 cell line method. Fucoidan of $1{\mu}g/mL$ showed the potential effect for converting nicotine to cotinine in the direct mixture method compared to control. Increase of conversion rate at the treatment of fucoidan is exhibited as 15 times compared to control. In Hep-G2 cell treatment, fucoidan showed the potential activity for converting nicotine to cotinine as 6 times compared to control. Therefore, fucoidan was shown to be effective in the conversion of nicotine into cotinine even though it is not higher content of polyphenol and flavonoid than its of green tea extract.

• Toxicological Research
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• v.25 no.1
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• pp.23-28
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• 2009

Some of the edible plants like apricot kernel, flaxseed, and cassava generate hydrogen cyanide (HCN) when cyanogenic glycosides are hydrolyzed. Rhodanese (thiosulfate: cyanide sulfurtransferases of TSTs; EC: 2.8.1.1) is a sulfide-detoxifying enzymes that converts cyanides into thiocyanate and sulfite. This enzyme exists in a liver and kidneys in abundance. The present study is to evaluate the conversion of apricot cyanogenic glycosides into thiocyanate by human hepatic (HepG2) and colonal (HT-29) cells, and the induction of the enzymes in the rat. The effects of short term exposure of amygdalin to rats have also been investigated. Cytosolic, mitochondrial, and microsomal fractions from HepG2 and HT-29 cells and normal male Spraque-Dawley rats were used. When apricot kernel extract was used as substrate, the rhodanese activity in liver cells was higher than the activity in colon cells, both from established human cell line or animal tissue. The cytosolic fractions showed the highest rhodanese activity in all of the cells, exhibiting two to three times that of microsomal fractions. Moreover, the cell homogenates could metabolize apricot extract to thiocyanate suggesting cellular hydrolysis of cyanogenic glycoside to cyanide ion, followed by a sulfur transfer to thiocyanate. After the consumption of amygdalin for 14 days, growth of rats began to decrease relative to that of the control group though a significant change in thyroid has not been observed. The resulting data support the conversion to thiocyanate, which relate to the thyroid dysfunction caused by the chronic dietary intake of cyanide. Because Korean eats a lot of Brassicaceae vegetables such as Chinese cabbage and radish, the results of this study might indicate the involvement of rhodanese in prolonged exposure of cyanogenic glycosides.

• Proceedings of the KIPE Conference
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• 2002.11a
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• pp.59-61
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• 2002

This research investigates electron beam to specification energy to Module that was generalized and schematized difference of curved line after existing V-I efficiency characteristic curve and irradiation. And will analyze cause of Si crystal Solar cell's efficiency addition and subtraction by 80keV electron beam investigation.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.243-247
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• 2012

The paper focuses on an anti-reflection (AR) coating deposited by PECVD in silicon solar cell fabrication. AR coating is effective to reduce the reflection of the light on the silicon wafer surface and then increase substantially the solar cell conversion efficiency. In this work, we carried out experiments to optimize double AR coating layer with silicon nitride and silicon oxide for the silicon solar cells. The p-type mono crystalline silicon wafers with $156{\times}156mm^2$ area, 0.5-3 ${\Omega}{\cdot}cm$ resistivity, and $200{\mu}m$ thickness were used. All wafers were textured in KOH solution, doped with $POCl_3$ and removed PSG before ARC process. The optimized thickness of each ARC layer was calculated by theoretical equation. For the double layer of AR coating, silicon nitride layer was deposited first using $SiH_4$ and $NH_3$, and then silicon oxide using $SiH_4$ and $N_2O$. As a result, reflectance of $SiO_2/SiN_x$ layer was lower than single $SiN_x$ and then it resulted in increase of short-circuit current and conversion efficiency. It indicates that the double AR coating layer is necessary to obtain the high efficiency solar cell with PECVD already used in commercial line.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.6
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• pp.1277-1281
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• 2005

FPGA has been widely used in communication system. In this paper, we made 10 layers PCB on protection of signal noise and data lose with FPGA. We analyzed about change of the data transmission speed and length according to input frequency. The length of transmission line from FPGA's output-pin to output-port on PCB board is 13cm and extended lengths for test are 30cm, 60cm and 10cm. We knew that data can be stably transmitted to 100Mbps at transmission line length of 30cm.

• Korean Journal of Environmental Agriculture
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• v.19 no.2
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• pp.147-153
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• 2000

Cigarette smoking deals a harmful effect directly to smokers and even to non-smokers through environmental tobacco smoke. The major damaging component in cigarette smoke is nicotine which converts to various carcinogens. Among the carcinogenic metabolites, nitrosamine-4-(methylnitrosamino)-1- (3-pyridyl)-1- butanone (NNK) is responsible for many types of lung cancers. Recent studies report that activation of NNK is markedly inhibited in the presence of cotinine, a safer metabolite from nicotine. It is well known that tea extract have potentials to prevent cancers. This study aims to correlate green tea's potential for cancer prevention with an accelerated formation of cotinine. In the presence of tea extract, a nicotine to cotinine conversion was studied in established cell lines and xenopus oocytes. Among three lines of cell used, PLC/PRF5 and 293 cells showed a fast turnover from nicotine to cotinine while HepG2 cell line showed a marginal difference between groups treated and non-treated with tea extract. A microinjection procedure using Xenopus oocyte was utilized to probe for the effect of tea extract in accelerating nicotine conversion to cotinine. According to this procedure, tea extract's unusual potential for converting nicotine to cotinine is also substantiated. Overall, this present study indicated that tea extract have an unusual effect on conversion of nicotine to cotinine in cells.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.123.1-123.1
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• 2017

Hybrid solar cells have intensively studied in recent years due to their advantages such as cost effectiveness and possibility of applications in flexible and transparent devices. It is critical to fabricate individual layer composed of organic and inorganic materials in the hybrid solar cell at low cost. Therefore, it is required to manufacture cheaply and enhance the photon-to-electricity conversion efficiency of each layer in the flexible solar cell industry. In this research, we fabricated pure Cu metal mesh electrode prepared by using electroplating and/or electroless plating on the Ni mold which was manufacture through photolithography, electroforming, and polishing process. Copper mesh was formed on the surface of nickel metal working master when pulsed electrolytic copper deposition were performed at various plating parameters such as plating time, current density, and so on. After electrodeposition at 2ASD for 5~30seconds, the line/pitch/thickness of copper mesh sheet was $1.8{\sim}2.0/298/0.5{\mu}m$.