• 제어로봇시스템학회논문지
• /
• 제8권10호
• /
• pp.833-841
• /
• 2002

We develope a model that can manipulate the reflux ratio of a batch distillation process in real time for optimal operations. Firstly, reflux ratio decision model for batch distillation unit was developed using the simple short-cut method. Secondly, more detailed rigorous method was applied to improve the accuracy of the model. Based on these models, operational strategies for the optimal reflux ratio was proposed. The results are illustrated with suitable examples and compared with the results using commercial simulator.

• Applied Biological Chemistry
• /
• 제37권1호
• /
• pp.9-13
• /
• 1994

백하주의 증류현상을 살피보기 위하여 전통약주인 백하주를 제조하고 압력(760, 460, 260 mmHg)과 환류비(3.1 : 1, 1 : 1) 및 충전물질의 유무에 따른 증류조작에 대하여 연구한 결과는 다음과 같다. 백하주의 alcohol함량은 14.2%, 산도는 8.3 g/100 ml, ethyl acetate는 49 ppm, fusel oil은 657 ppm이었다. 증류가 진행됨에 따라 증류액의 alcohol 농도는 감소하였으며, 분액별 alcohol 농도는 상압이 감압 보다 높았다. Still액과 증기상의 alcohol 농도의 관계를 나타내는 기울기는 압력이 높을수록 크게 나타났다. 비환류시 증류종말점은 8분액 이었지만 환류시는 5분액 이었다. 또한 환류시 alcohol 평균농도는 환류비가 높을수록 증가하였으며, 상압상태에서 환류비가 3.1 : 1과 1 : 1 일 때 각각 0.56, 0.54 mole이었다. 증류속도는 증류가 진행됨에 따라 감소하였으며, 상압보다 감압에서 빨랐고 충전상태의 260 mmHg에서 0.14 ml/sec로 가장 빨랐다. 환류시는 환류비가 높을수록 감소하였고 평균 증류속도는 상압상태에서 환류비가 3.1 : 1과 1 : 1일 때 각각 0.05, 0.06 ml/sec이었다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
• /
• pp.941-946
• /
• 1992

Three different reflux policies are compared for a batch distillation process in which a fixed recovery with a given average purity of the distillate is required ; the first, for the constant distillate purity ; the second, for the constant reflux ratio ; finally, for the optimal reflux policy which gives the minimum operation time. The optimal reflux policy was obtained using pontryagin's maximum principle. Througy the numerical simulations for the three different binary mixtures, it was found that the time advantage of the optimal reflux operation over the constant overhead composition operation varies form 10.0 to 22.4% and the advantage over the constant reflux operation varies from 1106 to 36.6% in the three cases considered.

• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 1997년도 춘계학술발표회논문집(1)
• /
• pp.322-326
• /
• 1997

The condensate in a single vertical reflux condenser with a tube of the large L/D ratio could carried over in both ways of fill-and-dump and the annular occurrent to steam flow. From the experimental observation made, a theoretical model based on the lumped parameter method is made to understand the dynamics of the reflux condenser. The present model predicts well the time period of fill-and-dump model and the natural vibrational frequency of the water column. This could be a first step to understand the complex phenomena in the reflux condenser such as itd improved thermal performance due to the well controlled pulsation in steam flow and the tube-to tube effect in the multi tube reflux condenser.

• Membrane and Water Treatment
• /
• 제4권4호
• /
• pp.251-263
• /
• 2013

The internal reflux effect on dialysis through the retentate phase of a countercurrently cross-flow rectangular module is investigated. Theoretical analysis of mass transfer in cross-flow devices with or without recycling is analogous to heat transfer in cross-flow heat exchangers. In contrast to a device without reflux, considerable mass transfer is achievable if cross-flow dialyzers are operated with reflux, which provides an increase in fluid velocity, resulting in a reduction in mass-transfer resistance. It is concluded that reflux can enhance mass transfer, especially for large flow rate and feed-concentration operated under high reflux ratio.

• 한국유기농업학회지
• /
• 제30권1호
• /
• pp.75-87
• /
• 2022

본 연구는 다량 미네랄 6종 및 미량 미네랄 8종이 함유된 천연 미네랄 워터의 기능성을 확인하기 위해 역류성 식도염 유발 동물모델을 이용하여 개선 효과를 분석하였다. RAW264.7에서의 세포 생존율 측정 결과를 통해 미네랄 워터는 세포에 대한 독성이 없음을 확인하였으며, 역류성 식도염 동물모델에서 위 내용물 역류에 의한 식도 손상을 감소시켰으며, 식도 점막 보호 작용으로 인해 세포 연접 단백질 발현을 억제하였다. 따라서, 미네랄 워터의 식도 보호 작용은 조직 내 염증성 단백질 및 점막 재생 관련 단백질을 조절함으로써 나타난 것으로 사료된다. 이러한 연구 결과를 통해, 미네랄 워터의 기능성을 확인함으로써 음용수, 식품 생산 등의 다양한 산업 분야에서의 활용성과 가축 생산에 있어 면역증진 및 염증 관련 질병에 대처할 수 있는 친환경 기능성 사료첨가제로서의 미네랄 워터의 이용 가치를 확인할 수 있었다.

• 생약학회지
• /
• 제51권4호
• /
• pp.349-359
• /
• 2020

Gastroesophageal reflux disease (GERD) is a disease that stomach contents continually refluxing, and is currently on the rise worldwide. The purpose of this study is to find natural materials that can reduce side effects and effectively treat chronic acid reflux esophagitis (CARE), one of GERD. First, the antioxidant activity was confirmed by varying the mixing ratio of Coptidis Rhizoma and Evodiae Fructus, which are effective against chronic reflux esophagitis. After, animal experiments were conducted using a 1:1 (CE) and 1:2 (CEE) combination ratio of Coptidis Rhizoma and Evodiae Fructus, which had the best antioxidant efficacy. Gross lesion of esophageal mucosa after CE or CEE treatment showed a superior enhancement compared with that of CARE control rats. Additionally, its inhibited MAPK phosphorylation and led NF-κB inactivation through the suppression of IκBα phosporylation by regulating Nrf2/Keap-1, and NF-κB inactivation induced reduced protein expressions including inflammatory mediators and cytokines. Moreover, its improved esophageal barrier function through upregulating protein expressions of tight junction protein, whereas downregulating protein expressions of MMPs. Taken together, a mixture of Coptidis Rhizoma and Evodiae Fructus can attenuate the esophageal mucosal ulcer by inhibiting MAPK and NF-κB pathway, and upregulating proteins associated with tight junction.

• Biomolecules & Therapeutics
• /
• 제22권5호
• /
• pp.420-425
• /
• 2014

Esophageal reflux of gastric contents causes esophageal mucosal damage and inflammation. Recent studies show that oxygen-derived free radicals mediate mucosal damage in reflux esophagitis (RE). Chlorogenic acid (CGA), an ester of caffeic acid and quinic acid, is one of the most abundant polyphenols in the human diet and possesses anti-inflammatory, antibacterial and anti-oxidant activities. In this context, we investigated the effects of CGA against experimental RE in rats. RE was produced by ligating the transitional region between the forestomach and the glandular portion and covering the duodenum near the pylorus ring with a small piece of catheter. CGA (10, 30 and 100 mg/kg) and omeprazole (positive control, 10 mg/kg) were administered orally 48 h after the RE operation for 12 days. CGA reduced the severity of esophageal lesions, and this beneficial effect was confirmed by histopathological observations. CGA reduced esophageal lipid peroxidation and increased the reduced glutathione/oxidized glutathione ratio. CGA attenuated increases in the serum level of tumor necrosis factor-${\alpha}$, and expressions of inducible nitric oxide synthase and cyclooxygenase-2 protein. CGA alleviates RE-induced mucosal injury, and this protection is associated with reduced oxidative stress and the anti-inflammatory properties of CGA.

• 대한의생명과학회지
• /
• 제27권2호
• /
• pp.77-87
• /
• 2021

Reflux esophagitis (RE) is a disease that stomach contents, stomach acid, and pepsin continually refluxing and is curently increasing worldwide. This study was conducted to find natural materials that can reduce side effects and effectively treat RE. Animal experiments were conducted with a 1:1 (EA1), 1:5 (EA5) ratio of Evodiae Fructus and Arecae Semen known to be effective against reflux esophagitis. As a result of confirming the total lesion of the esophageal mucosa after EA1 or EA5 treatment in reflux esophagitis animals, it showed superior improvement compared to the RE-control rats. In addition, by regulating the expression of MPO and NADPH oxidase, the activation of NF-κB was inhibited, and the expression of COX-1 and COX-2 was regulated. Moreover, its improved esophageal barrier function through regulating protein expressions of tight junction protein and MMPs/TIMPs. Taken together, a mixture of Evodiae Fructus and Arecae Semen can attenuate the damage to the esophageal mucosa that not only inactivationed the NF-κB through oxidative stress control, but also by regulating tight junctions and MMPs/TIMPs. This effect was more excellent in the 1:1 mixture (EA1) than in the Evodiae Fructus and Arecae Semen 1:5 mixture (EA5).

• 공업화학
• /
• 제21권6호
• /
• pp.616-620
• /
• 2010

Liquid Crystal Display (LCD) 제조 공정에서 배출되는 폐유기용제에서 Propylene Glycol Monomethyl Ether Acetate (PGMEA)를 회수하여 재활용할 목적으로 다단계 증류탑을 이용하여 실험실적 규모의 증류 실험을 수행하여 최적 환류비를 결정하고자 하였다. 최종실험결과, 시료 A의 경우 PGMEA는 98% 이상, 수분 함량은 0.05% 이하이며, 시료 B의 경우 Reflux ratio를 6으로 한 경우 PGMEA 95% 이상, 수분 함량은 0.01% 이하이다(시료 A, B에 대한 내용은 Table 1에 명시함.). 이 값은 LCD 제조에 재활용할 수 있는 일반 수준인 90%보다 높은 수치로서 적용이 가능하다.