• 펄프종이기술
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• 제42권3호
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• pp.7-13
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• 2010

KOptimization and control of wet-end process provide a key solution to improve paper quality and production efficiency at the same time. Wet-end of paper machine is to determine three important influencing factors of papermaking i.e., retention, drainage and formation. Good formation of paper could be made at the cost of deteriorated retention or drainage. In the same manner increase of retention aid could cause the bad formation of paper. It is very important to find a proper retention chemical which may satisfy one of three factors without the sacrifice of other two. Laboratory scale analyzing or screening chemical additives of wet-end was reported in this study based on RDA sheet molding. Different from the conventional test method, simultaneous consideration of three important wet-end properties could be made by RDA and consequently more reliable prediction of actual paper machine wet-end could be expected.

• Journal of Animal Science and Technology
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• 제61권3호
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• pp.170-181
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• 2019

This study aimed to investigate the effects of temperature and retention time of the pressurized steam chamber on the ruminal fermentation characteristics and nutrient degradability of corn flakes in three Korean native Hanwoo cows and three Holstein cows implanted with a ruminal fistula. Corn kernels were categorized into 13 groups based on the chamber temperature (range, $100^{\circ}C-116^{\circ}C$) and retention time (range, 700-950 s). The pH value was lowest in T1 regardless of breed. Propionate concentration was the highest in T2 (p < 0.05). Total-volatile fatty acid (VFA) concentration was slightly but not significantly greater in T2 than in other conditions. Dry matter (p < 0.05), starch, and crude protein (p < 0.05) degradability were the highest in T1. At different incubation times and with different breeds, dry matter, starch, and crude protein degradability of corn flakes were the highest in T1. Thus, the present results indicate that the optimal temperature and retention time of the pressurized steam chamber should be $100^{\circ}C-105^{\circ}C$ and 700-720 s.

• Bulletin of the Korean Chemical Society
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• 제26권4호
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• pp.629-633
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• 2005

In the reversed-phase chromatography, the retention time of sample was investigated based on the molecular structure of compound. Several descriptors that were related to retention factors were selected, and then the values of descriptors were calculated with several softwares. The effect of retention factor was measured with calculated values, and the results were obtained that each descriptors of molecular structure of compound have different effect on the retention factor. Therefore, the empirical equation for seven types of descriptors considered was obtained, and it has high values of correlation coefficient. Furthermore, the experimental data and calculated values have good agreement.

• 대한핵의학회지
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• 제23권1호
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• pp.41-48
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• 1989

$^{99m}Tc-Pertechnetate\;(TcO_4^-)$ is concentrated by the stomach after intravenous injection, allowing the detection of ectopic gastric mucosa. It has been used to develop a noninvasive test of gastric secretion. However the cellular site of concentration is still controversial, that is whether mucin-secreting epithelial cell or acid-secreting parietal cell. This study is planned to investigate the effects of cimetidine and gastric acidity on the retention of $TcO_4^-$ in the gastric wall of the rat. Also we further attempted to clarify the uptake and secreting cell of $TcO_4^-$ in the gastric mucosa. One hundred rats were divided into two groups, preliminary (40 rats) and main examination group (60 rats). Preliminary examination group was composed of fasting group (20 rats) for the detection of the time for reaching stable $TcO_4^-$ retention ratio in gastric wall and post-prandial group (20 rats) for the detection of the time for reaching the maximal gastric acidity. Main examination group was composed of fasting group (30 rats), which was subdivided into control group (10 rats), cimetidine group (10rats), $Mylanta^{(R)}$ group (10 rats) and post?prandial group (30 rats), which was subaivided into 90 min group (10 rats), 90 min cimetidine group (10 rats), and 120 min group (10 rats). Retention ratio (%) of $TcO_4$ in the gastric wall and the pH of the gastric contents were measured in the extracted stomach of the six groups. Gastric wall retention ratio of $TcO_4^-$ was calculated by the gastric wall radioactivity (cpm) divided by total gastric radioactivity (cpm) at 30 mins after intravenous injection of 0.4 mCi of $TcO_4^-$. The results were as follows: 1) The time required for reaching stable $TcO_4$ retention ratio and the lowest gastric PH were 30 min and 90 min, respectively. 2) In the fasting group, the gastric wall retention ratio of $TcO_4^-$ was significantly increased in the cimetidine group, compared with the control group (P < 0.01). However there was no significant difference between the control and $Mylanta^{(R)}$ group 3) The $TcO_4^-$ retention ratios of 90 min and 120 min groups were lower than that of the fasting control group (p < 0.05), either. After administration of cimetidine, the retention ratio was significantly increased in 90 min group (p < 0.01). 4) While $TcO_4^-$ retention ratio and gastric pH were well correlated in the post-prandial 120 min group (r=0.7112, p<0.05), in the post-prandial 90 min and 90 min cimetidine groups correlated poorly. However, there was no correlation in the three fasting groups at all. Referring the above results, we infer that $TcO_4^-$ is secreted into the gastric lumen by both parietal and non-parietal cells, with dominant non-parietal $TcO_4^-$ secretion in the fasting state and dominant parietal $TcO_4^-$ secretion in the stimulated state.

• 한국식품영양과학회지
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• 제19권6호
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• pp.555-564
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• 1990

과실쥬스와 같은 자연 생산물의 동결건조에 있어서 가공처리중 휘발성분의 보유력 변화를 알아보기 위하여 headspace gas chromatography 기술의 특징을 이용하여 동결건조 속도, 초기 고형물의 함량 및 압력 등이 어떠한 영향을 미치는가에 대한 실험결과는 다음과 같다. 동결건조 속도가 휘발성분의 보유력에 대한 영향은 현저하였으며, 동결시간이 길수록 뚜렷하였다. 동결 건조 제품에서 휘발성분의 보유력은 동결에 의해 영향을 받았다. 동결건조 조건하에서 가장 많은 휘발성분의 손실은 동결건조 초기단계, 즉 1~2 시간 사이에서 일어났다. 휘발성분의 보유력은 초기 고형물의 함량이 많을수록 높았다. 동결속도가 빠를 때보다는 늦을 때가 휘발성분의 보유력이 높았으며 높은 압력에서보다 낮은 압력에서 높았다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 하계종합학술대회 논문집(2)
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• pp.367-370
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• 2004

We fabricated PLT(5) thin film on $Pt/TiO_x/SiO_2/Si$ substrate by using sol-gel method and investigated leakage current, switching and retention properties. The leakage current density of PLT(5) thin film was $3.56{\times}10^{-7}A/cm^2$ at 4V. In the examination of switching properties, pulse voltage and load resistance were $2V{\~}5V$ and $50{\Omega}{\~}3.3k{\Omega}$, respectively. Switching time had a tendency to decrease from 520ns to 140ns with the increase of pulse voltage, and also the time was increased from 140ns to $13.7{\mu}s$ with the increase of load resistance. The activation energy obtained from the relation of applied pulse voltage and switching time was about 143kV/cm. The error of switched charge density between hysteresis loop and experiment of polarization switching was about $10\%$. Also, polarization in retention was decreased as much as about $8\%$ after $10^5$s.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.1173-1176
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• 2004

In a previous work we reported the bistable property by doping a chiral material in a splay cell. The bistable states are the splay state and the metastable 180$^{\circ}$twist state. The retention time of the metastable state can be changed by the variation of d/p (cell gap over pitch), cell gap, pretilt angle, azimuthal anchoring force, liquid crystal material, and so on. In this paper we will present uniform bend transition and twist retention time improvement in a multi-domain BCSN LC cell by using the multi cell gap method.

• Journal of Nutrition and Health
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• 제22권3호
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• pp.159-166
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• 1989

The effect of blanching time and power settings of microwave oven on the ascorbic acid retention in seven kinds of vegetables were investigated. The vegetable were blanched for 120 or 180 sec. at three different power setting, 650 watt(high power), 500 watt(medium power) and 160 watt(low power). The retentions of ascorbic acid in cabbage, garland chrysanthemum, mungbean sprout, amaranth and carrot were higher when they were blanched at the high power than those blanced at the lower power stettings. Blanching of spinach and yul-moo(small korean radish) showed that the vitamin was more retained by the medium power heating. Blanching at the low power revealed that the ascorbic acid retention was reduced remarkably as the blanching time increased. From the scoring difference tests the 10-panel members indicated that the texture of three-tested vegetables was more acceptable when they were blanched at the high power setting.

• Journal of Information Display
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• 제12권4호
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• pp.195-198
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• 2011

Proposed herein is a flexible bistable chiral splay nematic display mode with an enhanced memory retention time under external distortion. By adopting the polymerized reactive-mesogen structure mixed in a liquid crystal layer, local anchoring energy is generated on the boundary between the polymer structures, and the relaxation from the ${\pi}$-twisted state to the initial splay state could be interrupted. As a result, the memory retention time becomes significantly longer, and the stability against the external distortion is enhanced.

• 환경위생공학
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• 제11권3호
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• pp.63-68
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• 1996

This study was to discuss limiting factors influenced on the removal efficiencies of nitrogenous compounds investigated using the polypropyrene media which was to attach microorganism in order to apply the fixed-biofilm process. The main limiting factors are the hydraulic retention time (HRT), C/N ratio, $COD/NO_{3}-N$ ratio and temperature. The hydraulic retention time HRT were 6, 8, 10, 12 hrs and the C/N ratio range was 2.5-9.5. The $COD/NO_{3}-N$ ratio range was 3.2-21.9 and the temperature were 15, 20, 25, 30, $35^{\circ}C$, respectively. The results of this study are summerized as follows. 1. Hydraulic retention time (HRT) to obtain removal efficiencies of T-N higher than 85% had to be 10 hrs above. 2. The removal efficiencies of T-N decreased at C/N ratio from 6.2 to 4.8 in this anoxic-contact aeration system. 3. Denitrification rate decreased at $COD/NO$_{3}$-N$ ratio from 8.0 to 5.0 4. As temperature increased, removal efficiencies of T-N increased.