• Journal of the Korean Wood Science and Technology
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• 제34권3호
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• pp.64-72
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• 2006

참식나무(Neolitsea sericea Koidz) 추출물의 염색특성을 구명하기 위하여 수피의 열수추출물에 대해 검토했다. 참식나무 수피의 열수추출물로부터 디에틸에테르와 에틸아세테이트로 분획하여 얻은 fraction을 TLC 및 column chromatography 처리하여 2개의 물질을 단리하였다. 기기분석을 통하여 단리물질의 구조를 해석한 결과, 알칼로이드 계열의 4H-dibenzoquinoline-2,10-diol, 5,6,6a,7-tetrahydro-1,9-dimethoxy-6-methyl (화합물I)과 리그난 계열의 lyoniresinol (화합물II)로 동정되었다. 이들 물질이 염색에 관여하는지 확인하기 위하여 HPLC를 사용하여 검토한 결과, 화합물(I)과 화합물(II)의 retention time이 참식나무 추출물 염색액 및 탈염액의 에틸아세테이트 fraction 중 주성분 피크의 retention time과 동일한 결과를 보였다. 따라서 화합물(I)과 화합물(II)가 참식나무 수피의 주요 염착물질임을 확인할 수 있었다.

• 한국환경농학회지
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• 제21권2호
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• pp.144-148
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• 2002

본 연구에서는 농어촌취락배수의 효율적 처리를 위해 수생식물인 부레옥잠과, 미나리를 이용한 연속식 실험에서 유기물부하(COD)와 Total N, Total P 등을 HRT와 농도를 달리하여 제거효율을 측정하였다. 유기물(COD)의 제거효율은 HRT가 2 day인 부레옥잠조에서는 평균 50%의 제거율을 보였으며, 미나리조에서는 HRT 1.2$\sim$2 day 동안 30$\sim$50%의 제거율을 보였다. 영양염류의 제거효율은 총 질소의 경우 부레옥잠조는 약 329 kg $N/ha{\cdot}day$의 부하에서 HRT 2$\sim$3 day인 경우 40$\sim$53%가 제거되었으며, $NH_4^+-N$의 제거효율은 평균 52%로 Total N의 제거효율보다 다소 높았으며, 인은 8.2 kg $P/ha{\cdot\}day$의 부하에서 HRT 2$\sim$3 day인 경우 31$\sim$40%로 조사되었다. N 및 P 흡수율은 미나리보다 부레옥잠이 높게 나타났으며, 인의 흡수율은 질소의 흡수에 비해 낫게 조사되었다.

• 한국식품과학회지
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• 제22권5호
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• pp.497-502
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• 1990

삼투압 농축중 설탕용액의 농도와 온도 및 침지시간에 따른 감자 내부의 수분손실, 고형분 증가나 손실 및 몰랄농도를 반응 표면 분석법으로 조사하였고, 이차 다항 회귀 모델로써 예측하였다. 또한 삼투압 농축과 데치기가 6%수분(wet basis)까지 열풍조건시 비타민 C 함량유지에 미치는 효과를 평가하였다. 감자내부의 수분손실, 고형분 증가나 손실, 몰랄농도, 속도 매개변수 및 비타민 C 함량에 가장 크게 영향을 미치는 요소는 설탕농도이었고 그 다음 침지시간과 침지온도 순이었다. 수분손실과 설탕흡수는 초기 10분간 침지과정에서 빠르게 이루어진 후 증가현상이 둔화되었다. 설탕용액 $(60\;Brix,\;80^{\circ}C)$에서 20분간 침지 후 44.6%의 수분손실이 되었다. 삼투압 농축후 건조시킨 감자가 데치기 한 후 건조시킨 감자보다 높은 비타민 C 함량을 유지하였다. 30% 이상의 수분손실과 50% 이상의 비타민 C 함량유지의 관점에서 삼투압농축공정의 최적조건은 $60-70^{\circ}C$의 침지온도와 60 Brix의 설탕농도 및 16-20분간의 침지시간이었다.

• Bulletin of the Korean Chemical Society
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• 제34권6호
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• pp.1703-1707
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• 2013

A fast and simple sampling and sample preparation device, (NTD) has been developed and applied to sample and analyze volatile components from ground coffee beans. Coffee fragrances and other volatile organic compounds (VOCs) were sampled by the NTD and then analyzed by gas chromatograph-mass spectrometry (GC/MS). Divinylbenzene (DVB) particles (80/100 mesh size) were the sorbent bed of the NTD. More than 150 volatile components were first identified based on the database of the mass library and then finally 30 fragrances including caffeine were further confirmed by comparing experimental retention indices (i.e. Kovat index) with literature retention indices. Total sampling time was 10 minutes and no extra solvent extraction and/or reconstitution step need. Straight n-alkanes (C6-C20) were used as retention index probes for the calculation of experimental retention indices. In addition, this report suggests that an empty needle can be an alternative platform for analyzing polymers by pyrolysis-GC/MS.

• JSTS:Journal of Semiconductor Technology and Science
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• 제1권1호
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• pp.1-14
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• 2001

Current status and prospects of FET-type FeRAMs (ferroelectric random access memories) are reviewed. First, it is described that the most important issue for realizing FET-type FeRAMs is to improve the data retention characteristics of ferroelectric-gate FETs. Then, necessary conditions to prolong the retention time are discussed from viewpoints of materials, device structure, and circuit configuration. Finally, recent experimental results related to the FET-type memories are introduced, which include optimization of a buffer layer that is inserted between the ferroelectric film and a Si substrate, development of a new ferroelectric film with a small remnant polarization value, proposal and fabrication of a 1T2C-type memory cell with good retention characteristics, and so on.

• Membrane and Water Treatment
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• 제9권5호
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• pp.343-351
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• 2018

As membrane fouling is based on various factors, it is a complex phenomenon that is hard to estimate. This study investigated membrane fouling in a thermophilic jet loop membrane bioreactor (JLMBR). With this purpose, four different empirical membrane fouling models with different sludge retention times were applied on the flow data obtained in the system. As a result of the model implementation, it was found for all sludge retention times that, standard blocking is effective in the first 1.5 hours of filtration, while cake filtration was dominant in the remaining duration. Additionally, it was observed that as the sludge retention time increases, membrane fouling rate decreases.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2007년도 추계학술발표논문집
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• pp.21-33
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• 2007

CPAM has been applied to the paper industry for the purpose of wet-end improvement for a long time. And molecular weight and charge density have been managed most important quality factors to make CPAM for this application. Recently branched CPAM was developed to improve retention and drainage characteristics and we considered branch degree of CPAM as important factor as molecular weight and charge density. In this experiment, we tried to investigate physical and chemical properties to determine branch degree and flocculation efficiency using Arbocell pulp which was recently developed micro size pulp and finally we applied retention and drainage test under the ONP stock condition.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.259-262
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• 2005

Image retention is a kind of fatal shortcoming of the AC PDPs for realizing high-quality picture. In this work, the measurement method of image retention was proposed using temporal measurement of luminance, CIEXYZ tristimulus values, IR emission of reset pulse, and temperaturel. On the base of temporal measurement of luminance, CIEXYZ tristimulus value, and IR emission of reset pulse, the retention time of Ne+5%Xe gas-mixture discharge was about 2 hours after white window image. However, it was about 20 minute on the base of temporal measurement of temperature.

• 콘크리트학회논문집
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• 제11권3호
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• pp.153-160
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• 1999

Water soluble hydroxyalkyl methycellulose ethers are used in a variety of applications incluing building industry as a supplementary agent used for incresing adhesives, water retention capacity, workability and viscosity modify. Water retention capacity(WRC) is the capability to contain water in the ploymer chain under condition of being mixed with cement. In general, the WRC is affected by the viscosity, the adding amount, the particle size, the rate of dissolving and the amount of substituted chemical in cellulose ethers. In the other words, WRC is increased as higher the viscosity, more adding amount, finer the particle size and longer the dissolving time of cellulose ethers. This thesis investigated each factor that effect the WRC, particularly the relation between degree of substitution(DS), molar of substitution(MS) and WRC. It is observed that WRC is not nearly affected by DS of cellulose ethers, but is changes proportionally as MS increases in the narrow range(0.10~2.25)

• Bulletin of the Korean Chemical Society
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• 제14권6호
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• pp.692-696
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• 1993

Prediction of retention times in transition metal-mandelate and transition metal-tartrate complex systems were studied on the cation exchanger. Plots of k' vs [mandelate] and k' vs [tartrate] were obtained under the condition of a constant competing cation concentration. The equation to predict the retention time of transition metal ion was derived from the ion exchange equilibria. Individual capacity factors (${k_1}',\;{k_2}'$) and stability constants ($K_1,\;K_2$) of the complexes were calculated from the non-linear least square method. Good resolution of the transition metals was predicted by the stepwise equation in the gradient method. The values of retention times from the calculation and the experiment agreed well each other.