• Korean Journal of Poultry Science
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• v.19 no.4
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• pp.217-225
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• 1992

This research was carried out to determine the 25-Hydroxyvitamin $D_3$[25(OH)$D_3$] content in liver of broiler Hubbard chicks fed vitamin VD-deficient diet for 31 days in a subdued light room and exposed to UVB light (maximum intensity at 297nm) with dose of 0.204 or 0.408 mJ/$\textrm{cm}^2$(30 or 60 min irradiation) . The lipid in liver collected at 0~138 hr after irradiation was extracted by chloroform-methanol(2：1, v /v) and 25(OH)$D_3$ fraction was separated by Sep-Pak silica cartridge. The 25(OH)$D_3$ concentration was measured by normal phase HPLC. The negative control chicks Presented 25(OH)D$_3$17.5 ng/g liver. When 0.204mJ/$\textrm{cm}^2$ was treated to whole body of chicks, the 25(OH)$D_3$ level was increased to 37.8 ng/g at 12 hr after irradiation, the peak concentration, 40.5 ng /g was appeared at the time of 86 hr, and decreasing trend was shown thereafter until 138 hr, the final time in this study. When 0.408 mJ/$\textrm{cm}^2$ was applied, the 25(OH)$D_3$ content was 36.7 ng /g liver at 12 hr, 61.4 ng/g(maximum value ) was appeared at 42 hr, and 39.5 ng /g at 138 hr. The increased absolute amounts in liver 25(OH)$D_3$ were 23 and 43.9 ng/g as chicks were exposed to UVB light with dose of 0.204 and 0.408mJ/$\textrm{cm}^2$, respectively. Consequently, it was found that when double dose of UVB light was irradiated to the chicks, their liver samples produced nearly double 25(OH)$D_3$ at 42 hr after exposure, and the peak value was presented earlier by 24 hr than that in the low dose treatment.

• Electronics and Telecommunications Trends
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• v.19 no.6 s.90
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• pp.1-12
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• 2004

1960년대에 발명된 광섬유를 이용한 광통신기술은 1980년대 이래 빠르게 보급되었다. 특히 인터넷 트래픽이 폭발적으로 증가하기 시작한 1990년대 후반에 파장 분할 다중화(WDM) 기술이 상용화 되었으며 이 기술은 불과 수년 사이에 하나의 물리적인 광섬유 한 가닥을 통해 독립적인 수백 채널의 신호를 전송할 수 있는 수준에 이르렀다. 이에 더하여 ETDM 기술의 발전으로 채널 당 10Gbps 내지 40Gbps에 이르는 신호를 전송할 수 있게 되어 광섬유 선로 당 전송 용량은 테라급이 가능해졌다. 전송 용량의 빠른 확장과 과장된 수요 예측은 결국 공급 과잉을 초래하여 최근 수 년간 광전송 분야 시장이 침체된바 있다. 그러나 매년 약 두 배씩 꾸준히 증가하는 트래픽 덕에 최근에는 과잉 공급 분이 소진되어 가고 있으며 새로 시장이 활성화되고 있다. 새 시장에서는 종래의 점대점 방식을 넘어 메시형의 WDM 광 네트워크가 등장할 것이며 이에 따른 다양한 요소 기술을 요구하게 될 것이다. 본 고에서는 광전송 기술의 핵심 분야인 광 트랜스폰더 기술, 광 증폭기 기술, 그리고 광 네트워크 기술을 중심으로 현황과 발전전망을 알아본다.

• Advances in Traditional Medicine
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• v.5 no.1
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• pp.16-20
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• 2005

Grewia tiliaefolia is commonly used in India and several other countries for its ethnomedical properties. The antioxidant effect of 50% methanol extract of Grewia tiliaefolia bark was investigated by in-vitro and in-vivo methods. The extract exhibited $IC_{50}$ value of $51.40{\pm}3.98\;{\mu}g/ml$ in DPPH assay. In the in vivo experiments, the treatment was given at 250 and 500 mg/kg body weight doses orally for seven days and catalase, SOD, TBA-RS and ascorbic acid levels were estimated. Both the doses caused a significant increase in the levels of catalase in the liver and kidney, and SOD in the liver, kidney and blood serum. A significant decrease in the level of TBARS was also observed. These results suggest potent antioxidant nature of the extract.

• Journal of Ship and Ocean Technology
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• v.7 no.2
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• pp.40-47
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• 2003

LDV measurements in large cavitation tunnel around a propeller in operation are carried out to provide valuable information for more accurate wake-adapted propeller design and to study hull-propeller interactions. Effective velocities are computed by both the simplified vortex ring method and by RANS solver with the body force representing the propeller load. The former method uses the nominal velocities measured at the propeller plane as an input data of the numerical method and shows a better agreement with experimental data. The latter shows the qualitative agreement and may be used as an alternative design tools in the preliminary design stage.

• Analytical Science and Technology
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• v.11 no.2
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• pp.139-144
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• 1998

For the ambient monitoring of acrylamide, the adequate condition of sampling and analysis was checked. The adequate adsorbents and desorption solvents were tested. The combination of charcoal tube as a adsorbent and acetone as a desorption solvent showed 87% desorption efficiency. Flame ionization detector was used to detect acrylamide. The detection limit was 0.814 mg acrylamide in 1 L acetone. It is the equivalent concentration of 0.0203 mg acrylamide in $1m^3$ air if the volume of air collected was 40L. The permissible exposure level (PEL) of acrylamide in the workplace air recommended by Occupational Safety and Health Administration (OSHA, USA) is 0.3 mg acrylamide in $1m^3$ air. So, it is very simple and economic analytical method for acrylamide to be set in the industrial hygiene laboratories.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.4
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• pp.613-618
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• 2015

This paper proposed a low power CMOS Flash-SAR A/D converter which consists of a Flash A/D converter for 2 most significant bits and a SAR A/D converter with capacitor D/A converter for 8 least significant bits. Employment of a Flash A/D converter allows the proposed circuit to enhance the conversion speed. The SAR A/D converter with capacitor D/A converter provides a low power dissipation. The proposed A/D converter consumes $136{\mu}W$ with a power supply of 1V under a $0.18{\mu}m$ CMOS process and achieves 9.16 effective number of bits for sampling frequency up to 2MHz. Therefore it results in 120fJ/step of Figure of Merit (FoM).

• Advances in Traditional Medicine
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• v.6 no.2
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• pp.144-156
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• 2006

The effect of aqueous and alcoholic extracts of the fruit, leaf and stem of Melia azedarach Linn. (Meliaceae) on the spontaneous movements of both the whole worm and the nerve-muscle (n.m.) preparation of Setaria (S.) cervi and on the survival of microfilariae in vitro was studied. Alcoholic extracts of fruit, leaf and stem caused inhibition of the spontaneous movements of the whole worm and the n.m. preparation of S. cervi, while only aqueous extract of fruit caused inhibition of the spontaneous movements of the whole worm and the n.m. preparation of S. cervi. The initial stimulatory effect was not observed by the aqueous and alcoholic extracts of fruit on n.m. preparation. The concentrations required to inhibit the movements of the whole worm and n.m. preparation for alcoholic extracts of fruit, leaf and stem were 250, $40\;{\mu}g/ml$; 280, $40\;{\mu}g/ml$ and 270, $25\;{\mu}g/ml$ respectively, whereas an aqueous extract of fruit caused inhibition of whole worm and n.m. preparation at $200\;{\mu}g/ml$ and $40\;{\mu}g/ml$ respectively. Alcoholic extracts of the fruit, leaf and stem and aqueous extract of the fruit of M. azedarach caused concentration related inhibition on the survival of microfilariae (m.f.) of S. cervi. The $LC_{50}$ and $LC_{90}$ as observed after 6 h were found to be 5, 15, 10, 20 ng/ml and 10, 25, 20 and 35 ng/ml, respectively. This work was conducted in view of the exploration of potential antifilarial herbal drug.

• Journal of the Korean Magnetics Society
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• v.13 no.3
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• pp.103-108
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• 2003

A micromagnetic model and a Stoner-Wohlfarth model are used to analyze the effect of demagnetization field in patterned permalloy films. Permalloy films of 20 $\mu\textrm{m}$${\times}$(40 $\mu\textrm{m}$∼200 $\mu\textrm{m}$) are fabricated by DC magnetron sputtering and photo lithography. Measured magnetoresistance data of patterned permalloy films are compared with simulation results. The micromagnetic model gives a better agreement with the measured MR data than the Stoner-Wohlfarth model. Based on the simulation results, we propose a revised approximation formula for dernagnetization field in Stoner- Wohlfarth model for a few fm patterned magnetic films.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.485-494
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• 2000

According to the worldwide interest in controlling $CO_2$ which contributes to green house effect. new techniques of reducing $CO_2$ are under development. We have developed new technique for reducing $CO_2$. In low $CO_2$ concentration. the chemical absorption method is useful. In this study. the kinetics of the reaction between $CO_2$ and the sterically hindered amine solution with piperazine. have been investigated from measurements of the rate of absorption of $CO_2$ in the stirred vessel that has a horizontal liquid-gas interface, in the temperature range $30{\sim}70^{\circ}C$. The experiments were carried out in the range 10.130~20.260 kPa of partial pressure of $CO_2$, and in aqueous $2.0kmol/m^3$ AMP solution with $0{\sim}0.4kmol/m^3$ piperazine The experimental results are as follows: 1) The absorption rate of $CO_2$ into aqueous AMP + piperazine solution is gett ng faster than that of aqueous AMP absorbents with temperature. Because the activation energy of piperazine 57.147 kJ/mol is higher than that of AMP 41.7kJ/mol. therefore the effect of piperazine on absorption rate increases with temperature. 2) Compared with aqueous AMP solution. the absorption rate of $CO_2$ into AMP + piperazine solution increases from 6.33% at $30^{\circ}C$ to 12% at $70^{\circ}C$, so AMP + piperazine solution is thought to be a better than AMP solution, 3) The reaction rate constants of piprazine in aqueous AMP solution with $CO_2$ have been determined as 217.21, 420.46, 707.00 and $3162.167m^3/kmol{\cdot}s$ respectively at 30, 40, 50 and $70^{\circ}C$ but these results are higher than those of Xu which were 186.7. 367.32. 693.01. $2207.65m^3/kmol{\cdot}s$ at 30, 40, 55, $70^{\circ}C$in aqueous MDEA solution. So the regression analysis of the data has led to the following equation In $k_p$ =28.324-6934.7/T.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.10-14
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• 2005

This report deals with a feeding system of the Coaxal grinding machine, processing optical ferrule. This report also examines the applicability of using the feeding system for the Coaxial grinding machine, by mean of conducting performance estimation. The results are as follow; Repeatability of regulating wheel is $17{\mu}m$, R/W rotation accuracy is between $30\;\~\;40{\mu}m$. This means 'Rotation accuracy' is lower than the concentricity level. Backlash generation level at the feeding system of the grinding wheel is under $1{\mu}m$, thereby positioning accuracy is controlled within $2{\mu}m$ In terms of repeatability, you can find occasional error at the returning process from the starting point. This error is resulted from the measurement tolerance of the starting point sensor. We will get the repeatability level under control by $1{\mu}m$, through improving the soft-ware used and up-grading the sensor at the starting point.