• Natural Product Sciences
• /
• v.3 no.1
• /
• pp.11-13
• /
• 1997

From the methanolic extract of defatted tender leaf of Camellia sinensis a new 4-hydroxy angular furocoumarin $C_{12}H_8O_5$, m.p. $212^{\circ}C$, was isolated using high-speed counter-current chromatographic technique. The structure of the compound was established as 4-hydroxy-2'-methoxy angular furocoumarin on the basis of physical methods viz. $^1H$ NMR, $^{13}C$ NMR and MS.

• Proceedings of the Korean Society of Grassland Science Conference
• /
• 1999.06a
• /
• pp.93-93
• /
• 1999

4품종의 알팔파 (Medicago sativa L.) 종자로부터 직접 캘러스를 유도하고, 형성된 캘러스로부터 식물체를 재분화하는 조건을 확립하였다. 공시품종중 "Vernal" 품종이 캘러스 유도 및 재분화에서 가장 우수한 것으로 판명되었으며, SH(Schenk and Hildebrandt), MS (Murashige and Skoog), N6 (Chu) 배지중에서 SH 배지가 캘러스 유도와 재분화시에 모두 유리한 것으로 나타났다. 캘러스 유도 및 증식시에는 2,4-D를 3mg/$\ell$ 농도로 첨가한 SH-3 배지에서 가장 효율이 좋았으며, kinetin을 첨가하거나 kinetin의 농도가 높을수록 캘러스 형성 정도는 급격히 저하되었다.(중략)저하되었다.(중략)

• The Journal of the Acoustical Society of Korea
• /
• v.4 no.3
• /
• pp.3-7
• /
• 1985

본 논문은 전 전자식 교환기에 사용되는 MFC 수신기를 설계하기 위해서 FIR-Filter를 사용한 논문이다. FIR-filter를 설계함에 있어서, Remetz Algorithm을 사용한 Mellellan의 방식이 적용되었으며 인접주파수를 정확히 구분하기 위하여 85차의 고차필터를 설계하였고, 필터의 출력 데이터 15개의 합으 로써 각 주파수에 대한 판별값으로 정하였다. 인접 주파수를 구분하는 출력 power의 결과는 최근의 FGT-MFC 수신기의 출력 power의 결과와 비교 하였을 때, S/N 비면에서 5dB 이상의 향상을 보였으 며, 133개의 입력데이타를 사용하는 FGT-MFC 수신기보다 4.2ms 빠른 응답특성을 나타냈다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2001.04a
• /
• pp.289-291
• /
• 2001

본 논문에서는 실시간처리 리눅스에 기반한 VoIP 단말기를 설계 구현한다. 설계 구현된 하드웨어 시스템은 i386 프로세서를 기반으로 설계되며, 실시간음성처리 지원을 위해 음성코덱 칩과 실시간처리 리눅스인 RTLinux를 사용하여 실시간 음성처리 모듈을 구현한다. 설계 구현된 시스템의 테스트 및 타당성 검증을 위해 LAN환경에서의 음성채팅 프로그램에 적용하여 통화품질을 시험하였다. 음성처리에 사용한 음성처리 모듈은 ITU-T 음성 코덱인 G.723.1 사용하여 30ms 내에 24 바이트로 인코딩/디코딩된 음성 데이타를 전송하도록 구현하였다.

• Journal of Applied Biological Chemistry
• /
• v.57 no.2
• /
• pp.159-160
• /
• 2014

An antifungal antibiotic was extracted three times using n-butanol from the culture broth of Bacillus sp. Bioassayguided column chromatography with silica gel and Sephadex LH-20 yielded 62 mg of the original active compound from 1 L of culture broth. The minimal inhibitory concentration values were 25 and $50{\mu}g/ml$ against Pyricularia oryzae and Pellicularia filamentosa, respectively. Based on results obtained from the analysis of the structure of the antibiotic using MS, NMR, and IR spectroscopy, the antifungal antibiotic was shown to consist of only six of fructose.

• Bulletin of the Korean Chemical Society
• /
• v.15 no.9
• /
• pp.739-743
• /
• 1994

A spectroelectrochemical system assembled with a white light source, bifurcated optical fiber, Oriel Multispec spectrograph, and a charge-coupled device (CCD) detector is described. The system is shown to be capable of acquiring a whole spectrum in the spectral range of 290-800 nm in 25 ms or a longer period during electrochemical experiments at reflective working electrodes such as platinum or mercury. The utility of the system in studying electrochemical reactions during the potential scan, galvanostatic electrolysis, or after the potential step is demonstrated.

• Journal of the Korean Chemical Society
• /
• v.63 no.5
• /
• pp.387-391
• /
• 2019

• Korean Journal of Materials Research
• /
• v.4 no.8
• /
• pp.952-957
• /
• 1994

Fe/Co and FeN/CoN multilayer films were prepared by using RF and DC magnetron sputter^ ing technique with Ar or a mixture of Ar and $N_{2}$ gas. Annealing treatment was carried out in a vacuum at temperatures between $100^{\circ}C$ and $500^{\circ}C$ for lhour. Saturation magnetization (MS) and coercivity (Hc) of Fe/Co mutilayer films were investigated as a function of Fe layer thickness and annealing temperature. Permeability ($\mu$) was also examined. Saturation magnetization of 1.8T and coercivity of 1.80e were obtained for the as-deposited Fe/Co($70 \AA /15 \AA$) multilayer film. The Coercivity(Hc) did not change from 1.8 Oe till the annealing temperature $250^{\circ}C$ and then increased rapidly at higher annealing temperatures above $300^{\circ}C$. Coercivity(Hc) measured for the as-deposited FeN/CoN multilayer film was 5 Oe. It decreased gradually with annealing up to $250^{\circ}C$, and then increased rapidly at higher tempera tures.

• Journal of Korean Society on Water Environment
• /
• v.26 no.3
• /
• pp.446-453
• /
• 2010

This study was investigated nine nitrosamines in small tributary rivers, sewage treatment plants (STPs) and drinking water treatment plants. They are N-nitrosodimethylamine (NDMA), N-nitrosomethylethylamine (NMEA), N-nitrosodiethylamine (NDEA), N-nitrosopyrrolidine (NPYR), N-nitrosodi-n-propylamine (NDPA), N-nitrosomorpholine (NMOR), N-nitrosopiperidine (NPIP), N-nitrosodi-n-butylamine (NDBA) and N-nitrosodiphenylamine (NDPHA). The nine nitrosamines were analyzed by gas chromatography mass spectrometry (GC/MS) using solid phase extraction (SPE) with a coconut charcoal cartridge. Among the nine nitrosamines, NDMA, NMEA, NDEA, NDPA NDBA and NDPHA were detected in small tributary rivers and sewage tretment plants. In small tributary rivers, NDMA, NMEA, NDEA, NDPA, NDBA and NDPHA were obtained as ND~16.4 ng/L, ND~17.7 ng/L, ND~102.4 ng/L, ND~455.4 ng/L, ND~330.1 ng/L and ND~161.0 ng/L, respectively. Also NDMA, NMEA, NDEA, NDPA and NDBA were investigated ND~821.4 ng/L, 22.5~55.4 ng/L, 53.2~588.5 ng/L, ND~56.6 ng/L and ND~527.9 ng/L in STPs, respectively. In drinking water treatment plants, NMEA and NDEA concentration were increased to as high as 38.8 ng/L after ozonation process. However nitrosamines were decreased subsequent biological activated carbon (BAC) treatment process. It was supposed that nitrosamines were formed by $O_3$ oxidation and were removed by biodegradation of BAC.

• Journal of Food Hygiene and Safety
• /
• v.35 no.1
• /
• pp.23-30
• /
• 2020

This study investigated the migration levels of lead (Pb), cadmium (Cd), and arsenic (As) from food contact articles (glassware, ceramics, enamelware, and earthenware) into a food stimulant (4% v/v, acetic acid). Migration tests were performed at 25℃ for 24 h and all analyses were performed using Inductively-Coupled Plasma Mass Spectrometry (ICP-MS). The method was validated by linearity of calibration curves, limit of detection (LOD), limit of quantification (LOQ), recovery, precision, and uncertainty. In glassware, the migration concentrations ranged from not-detected (N.D.) to 752.21 ㎍/L and N.D. to 1.99 ㎍/L for Pb and Cd, respectively. In ceramics, the migration concentrations ranged from N.D. to 1,955.86 ㎍/L, N.D. to 74.06 ㎍/L, and N.D. to 302.40 ㎍/L for Pb, Cd, and As, respectively. In enamelware, the migration concentrations ranged from N.D. to 4.48 ㎍/L, N.D. to 7.00 ㎍/L, and N.D. to 52.00 ㎍/L for Pb, Cd, and Sb, respectively. In earthenware, the migration concentrations ranged from N.D. to 13.68 ㎍/L, N.D. to 0.04 ㎍/L, and N.D. to 6.71 ㎍/L for Pb, Cd, and As, respectively. All results were below the migration limits of Korea standards and specifications for food utensils, containers, and packages.