• 상하수도학회지
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• 제13권1호
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• pp.61-71
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• 1999

For a high-rate fermentation and recovery of organic acid, we have developed a new organic acid fermentation reactor with membrane filter, which is the most important part in the new advanced wastewater treatment system. The recovered organic acid is to be reused as an organic carbon source at denitrification process. Some experiments were conducted to compare the performance of acid fermentation at different SRTs, such as 5, 10, and 20 days. The total organic acid concentration produced during the runs was in the range of 2,100-2,900 (mgC/L). The conversion efficiency from substrate to organic acid reached to from 43% to 59%. The recovery rate of organic acid from substrate based on TOC was from 26% to 53%. Regardless of operational conditions, it has been able to maintain the membrane flux constantly, in the range of 0.4-0.46 ($m^3/m^2/day$). The transmembrane pressure drop was 0.2-0.3 (kg/cm) for 100 day's operation. The result of simulation is as follows. Organic removal efficiency of the new advanced treatment system is 95%. 73% of Nitrogen is removed. The removal efficiency of Phosphorus is 93%. By coqulation, soluble phosphorus is able to remove from the water treatment lines, which is impossible at conventional activated sludge system. The unit construction cost is 65000 (yen/m3) and it was 1.4 times than that of the standard activated sludge system. The unit operation cast is 7.7 ($yen/m^3/day$) and it was 1.3 times than that of the standard activated sludge system.

• Applied Biological Chemistry
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• 제51권3호
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• pp.177-182
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• 2008

피혁 제조 공정 중 발생하는 프레싱 스크랩으로부터 회수된 동물성 유지를 이용하여 lipase-catalyst 전이에스테르화 실험을 실시하였다. 실험 결과, 반응온도 $45^{\circ}C$에서 전환율이 극대점을 나타내었으며, 반응온도 $45^{\circ}C$ 이상에서는 전환율이 점차적으로 감소되었다. 초기 효소의 불활성화를 막기 위해서는 1.5몰씩 4단계에 걸쳐 투입하는 것이 가장 높은 전환율을 나타내었으며, 1.5몰 미만의 methanol로 투입 단계를 4단계 초과하여 사용하였을 경우에는 오히려 전환율이 낮아지는 경향을 나타내었다. 종류가 다른 4가지의 리파제를 사용하여 돈지의 전환율에 미치는 영향을 실험한 결과 C. antarctica를 기원으로 하는 Novozyme 435를 사용한 경우 82.2%의 전환율을 나타내어 가장 효과적이었다. 수분 함유량이 증가할수록 전환율이 저하됨을 확인하였다. 1.2wt.%에서의 전환율은 수분이 없는 상태에 비해 약 40%나 낮게 나타나 프레싱 스크랩으로부터 회수된 유지를 정제 공정을 거쳐 수분을 완벽하게 제거하는 것이 전환율을 높이는데 매우 중요한 인자임을 확인하였다. 고정화된 효소를 반복 사용 실험에서는 2회 사용할 때 약간 전환율이 감소하였으나 계속적으로 반복 사용할 때에는 전환율의 감소율이 둔화되었다. 전이에스테르화 반응을 우지에도 적용한 결과 전환율에서 돈지 84%보다 높은 88%를 나타내었다. 이 반응에 의해 생성된 지방산 에스테르는 SOx를 발생시키지 않고, 매연 발생량이 최소화되는 바이오디젤로서 사용될 수 있을 것으로 사료되었다.

• 신재생에너지
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• 제19권4호
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• pp.2-10
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• 2023

The current mandatory domestic biodiesel blending ratio is 3.5%, which is planned to be gradually increased to achieve carbon neutrality by 2050. The aim of this study was to improve domestic self-sufficiency in biodiesel raw oil by conducting a technical review on the possibility of utilizing waste oils, such as soup oil, chicken oil, and leather oil, as biodiesel feedstocks. These waste oils have an acid value that is too high to be converted directly into biodiesel. Therefore, a pretreatment to reduce the acid value is necessary. The neutralization process was examined as a potential technology for reducing the acid value. The oil recovery rate of the soup oil after neutralization was significantly low at 37.6 wt%. The oil recovery rates of leather oil and chicken oil were 66.49 wt% and 79.08 wt%, respectively. Based on biodiesel conversion experiment using waste oil with a reduced acid value, the conversions were analyzed as 89 wt%, 91.1 wt%, and 90.5 wt% for soup oil, leather oil, and chicken oil, respectively. Thus, it is technically possible to use soup oil, leather oil, and chicken oil as raw materials for producing biodiesel.

• Journal of Ginseng Research
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• 제33권3호
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• pp.194-198
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• 2009

본 연구에서는 수삼을 식품에 쓰이는 산화 방지제인 ascorbic acid와 citric acid로 처리하여 홍삼을 제조한 후 활성성분인 페놀화합물과 진세노사이드의 추출물내 함량 변화를 HPLC를 이용하여 살펴보았다. 분석결과 citric acid 처리 홍삼에서 esculetin과 quercetin 함량이 무처리 홍삼에 비하여 각각 3.5 배, 2.0 배 증가하였고 ginsenoside 함량 역시 citric acid 처리시의 Rg$_3$, Rd, Rh$_2$ 증가량이 ascobic acid 처리시에 비하여 높았다. 따라서 인삼추출물의 이들 특정활성성분 강화를 위하여는 citric acid 처리가 효과적인 것으로 판단된다.

• Macromolecular Research
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• 제10권5호
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• pp.259-265
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• 2002

The cure kinetics of blends of epoxy (DGEBA, diglycidyl ether of bisphenol A)/anhydride resin with polyamide copolymer, poly(dimmer acid-co-alkyl polyamine), were studied using differential scanning calorimetry (DSC) under isothermal condition. On increasing the amount of polyamide copolymer in the blends, the reaction rate was increased and the final cure conversion was decreased. Lower values of final cure conversions in the epoxy/(polyamide copolymer) blends indicate that polyamide hinders the cure reaction between the epoxy and the curing agent. The value of the reaction order, m, for the initial autocatalytic reaction was not affected by blending polyamide copolymer with epoxy resin, and the value was approximately 1.3, whereas the reaction order, n, for the general n-th order of reaction was increased by increasing the amount of polyamide copolymer in the blends, and the value increased from 1.6 to 4.0. A diffusion-controlled reaction was observed as the cure conversion increased and the rate equation was successfully analyzed by incorporating the diffusion control term for the epoxy/anhydride/(polyamide copolymer) blends. Complete miscibility was observed in the uncured blends of epoxy/(polyamide copolymer) up to 120 $^{\circ}C$, but phase separations occurred in the early stages of the curing process at higher temperatures than 120 "C. During the curing process, the cure reaction involving the functional group in polyamide copolymer was detected on a DSC thermogram.gram.

• Elastomers and Composites
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• 제46권1호
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• pp.37-44
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• 2011

Adipic acid(AA)와 diethylene glycol(DEG) 사이에서 일어나는 반응의 속도에 대한 유기나노점토(Cloisite 30B)의 영향을 규명하기 위하여 383K와 423 K에서 Br${\phi}$nsted acid인 p-toluene sulfonic acid(p-TSA)와 Lewis acid인 butylchlorotin dihydroxide를 촉매로 사용하여 에스테르 반응을 수행하였다. 촉매의 양은 전체반응물의 0.14 mol%만큼 사용하였다. 반응 생성물의 산가로부터 계산된 전환율 vs. 시간의 자료를 사용하여 반응속도를 해석하였다. [OH]/[COOH] 초기 몰비가 2인 상태에서 수행되는 polyester-diol 합성반응의 속도는 p-TSA 촉매하에서는 AA에 대하여 2차 반응으로, butylchlorotin dihydroxide 촉매하에서는 AA에 대하여 1차 반응으로 잘 해석되었으며 두 반응의 활성화 에너지는 각각 42.2 kJ/mol, 63.8 kJ/mol이었다. AA와 DEG에 Cloisite 30B를 5 wt% 첨가시키면 p-TSA 촉매는 활성이 크게 줄어 반응속도가 매우 느려졌으며, 이 때 활성화 에너지는 72.9 kJ/mol로 높게 계산되었다. Butylchlorotin dihydroxide 촉매는 Cloisite 30B의 첨가에 관계없이 거의 일정한 활성을 유지하였다. Butylchlorotin dihydroxide 촉매하에서 Cloisite 30B를 첨가한 반응의 활성화 에너지는 61.8 kJ/mol로 Cloisite 30B를 첨가하지 않은 반응의 활성화 에너지보다 약간 낮았다.

• Journal of Ginseng Research
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• 제44권4호
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• pp.544-551
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• 2020

Background: Previous studies have shown the insecticidal efficacy of ginsenosides. In the present study, we aimed to investigate the metabolic mechanism related to the inhibitory effect of panaxadiol saponins (PDSs) against the Asian corn borer Ostrinia furnacalis (Guenee). Methods: Third instar larvae of O. furnacalis were fed normal diets with different concentrations of PDSs for 4 days. The consumption index, relative growth rate, approximate digestibility, and conversion of ingested and digested food were recorded. A targeted gas chromatographye-mass spectrometry assay was performed to detect the profiles of amino acids, fatty acids, and carbohydrates in larvae of O. furnacalis. In addition, the activity of detoxification-related enzymes was determined. Results and Conclusions: PDSs decreased the consumption index, relative growth rate, approximate digestibility, and conversion of ingested and digested food in the 3rd instar larvae of O. furnacalis in a dose-dependent manner. PDSs decreased 15 free amino acids, 16 free fatty acids, and 5 carbohydrates and increased the levels of palmitoleic acid, palmitic acid, and 9-octadecenoic acid in the 3rd instar larvae. The activity of detoxification-related enzymes, such as acetylcholinesterase, glutathione S-transferase, cytochrome P450, carboxylesterase, trehalase, acid phosphatase, and alkaline phosphatase, was reduced in a dose-dependent manner in the 3rd instar larvae exposed to PDSs. These data confirmed the inhibitory effect of PDSs against growth, food utilization, and detoxification in the 3rd instar larvae of O. furnacalis and the potential for using PDSs as an efficient tool for insect pest management for O. furnacalis larvae.

• Asian-Australasian Journal of Animal Sciences
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• 제14권4호
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• pp.474-478
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• 2001

Eighteen Murrah male buffalo calves were allotted into three groups of six each. The calves in group I (control) were fed with whole milk, skim milk, calf starter and green maize fodder. The calves in group II (high butyric acid) and group III (low butyric acid) were fed with the same diet as control along with 24 ml and 12 ml of butyric acid/calf/day for 120 days, respectively for 120 days. Dry matter intake was higher in group II and III as compared with group I. Digestibility of dry matter, organic matter, crude protein, crude fibre, ether extract, neutral detergent fibre, acid detergent fibre, cellulose and hemicellulose was the highest in group II followed by group III and the control group. Body weight gain and conversion efficiency of dry matter, digestible crude protein and total digestible nutrients were better in group II. Cost of feed for per unit of live weight gain was the lowest in group II. It was concluded that dietary addition of butyric acid (24 ml/day) was economical and had positive effect on the performance of Murrah buffalo calves.

• Journal of Microbiology and Biotechnology
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• 제14권2호
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• pp.363-366
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• 2004

In order to obtain an industrial strain with higher L(+)-lactic acid yield, the wild type strain Rhizopus oryzae PW352 was mutated by means of Nitrogen ions implantation (l5 Kev, $7.8 \times 10^{14} - 2.08 \times 10^{15} ions/Cm^2$ and two mutants RE3303 and RF9052 were isolated. After 36 h shake-flask cultivation, the concentration of L(+)-lactic acid reached 131-136 g/l, the conversion rate of glucose was as high as 86%-90% and the productivity was 3.61 g/l.h. It was almost a 75% increase in lactic acid production compared with the wild type strain. Maximum fermentation temperature of RF9052 was increased to $45^{\circ}C$ from original $36^{\circ}C$. At the same time, the preferred range of fermentation temperature of RF9052 was broadened compared with PW352.

• 동력기계공학회지
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• 제11권2호
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• pp.64-71
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• 2007

The main purpose of this study is to analyze the characteristics of toluene removal by plasma, photocatalyst, and plasma/photocatalyst system with the major parameters such as flow rate, inlet toluene concentration and applied voltage, etc., experimentally. In the combined plasma/photocatalyst process, rates of toluene conversion are represented as 99% at flow rate 250, 500 mL/min while, below 97% at flow rate 1000 mL/min due to the low residence time(reaction time) at the same applied voltage 4173 voltage and toluene inlet concentration 50 ppm. The intermediate products are detected by GC/MS analysis showing the small amounts of benzoic acid, benzyl alcohol and residual ozone concentration $0.04{\sim}0.05$ ppm generated by plasma process in the present system.