• 대한기계학회논문집B
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• 제41권5호
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• pp.347-352
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• 2017

두 용액의 농도 차이를 이용하여 전기에너지를 생성하는 역전기투석 장치는 파리기후협약으로 인한 신재생에너지기술의 관심 증가와 높은 잠재적에너지량으로 인하여 활발한 연구가 진행되고 있는 분야이다. 상용화 관점에서 볼 때 역전기투석 장치의 출력 밀도를 최대화하는 것은 중요하며, 따라서 출력 밀도의 개선을 위한 다양한 방안이 논의되고 있다. 본 논문에서는 역전기투석 장치의 출력 개선 방법 중 유로 형상 변화에 초점을 맞췄다. 유로 형상 변수로서 종횡비, 개방비, 분배 및 배출 유로의 개수를 사용하였다. 결론적으로 유로의 종횡비는 감소하고 개방비와 분배 및 배출 유로의 개수가 증가할 때, 역전기투석 장치의 출력 밀도가 개선되는 것을 발견하였다.

• Natural Product Sciences
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• 제22권4호
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• pp.299-306
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• 2016

This study aimed to establish the quantitative method to analyze the content of peroxynitrite-scavengers belonging to polyphenols in six Korean Quercus species (Quercus mongolica, Q. dentata, Q. acutissima, Q. alienta, Q. serrata, and Q. variabilis) by HPLC. The twelve peroxynitrite-scavengers, flavanols (catechins: (+)-catechin, (-)-epicatechin, and (-)-epigallocatechin), flavonols (kaempferol and quercetin), flavonol glycosides (astragalin, quercitrin, and isoquercitrin), flavonol acylated glycosides (astragalin 6''-gallate and isoquercitrin 6''-gallate), gallic acid and its dimer (ellagic acid) were analyzed by HPLC. Further, anti-Alzheimer's activity was assayed in a passive avoidance testusing mice by measuring the retention latency (sec), the concentration of acetylcholine (ACh), and acetylcholinesterase (AChE) activity. Simultaneous analysis of the extracts of the six Quercus leaves was achieved on a Capcell C18 column ($5{\mu}m$, $250mm{\times}4.6mm\;i.d.$) with a gradient elution of 0.05% HAc and 0.05% HAc in $CH_3CN$. In the extract of Q. mongolica leaves, the content of gallic acid (32.53 mg/g), (+)-catechin (28.78 mg/g), (-)-epicatehin (22.03 mg/g), astragalin 6''-gallate (20.94 mg/g), and isoquercitrin 6''-gallate (44.11 mg/g) and peroxynitrite-scavenging activity ($IC_{50}$, $0.831{\mu}g/ml$) were high. This extract delayed the retention latency and inhibited acetylcholinesterase activity in scopolamine-induced memory impairment of mice, suggesting that it has anti-Alzheimer's activity.

• Journal of Pharmaceutical Investigation
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• 제39권1호
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• pp.23-27
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• 2009

A high performance liquid chromatographic (HPLC) method for the simultaneous determination of marker constituents, paeoniflorin and glycyrrhizin was established for the quality control of traditional herbal medicinal preparation, Sayuk-san (SYS). Separation and quantification were successfully achieved with a Waters XTerra RP18 column ($5{\mu}m$, $4.6mm\;I.D.{\times}150mm$) by gradient elution of a mixture of acetonitrile and water containing 0.03% phosphoric acid (pH 2.03) at a flow rate of 1.0 mL/min. The diode-array UV/vis detector (DAD) was used for the detection and the wavelength for quantification was set at 230 nm. The presence of paeoniflorin and glycyrrhizin in this decoction was ascertained by retention time, spiking with each authentic standard and UV spectrum. All two compounds showed good linearity ($r^2$>0.996) in a relatively wide concentration ranges. The R.S.D. for intra-day and inter-day precision was less than 7.3% and the limits of detection (LOD) were less than 55.7 ng. The mean recovery of each compound was $102.3{\sim}111.1%$ with R.S.D. values less than 4.6%. This method was successfully applied to the determination of contents of paeoniflorin and glycyrrhizin in three commercial products of SYS. These results suggest that the developed HPLC method is simple, effective and could be readily utilized as a quality control method for commercial SYS products.

• 한국자동차공학회논문집
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• 제5권4호
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• pp.130-141
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• 1997

Work on the reduction of particulate matter(PM) from a diesel vehicl has led to a new trp system and a control method to control the combustion rate of the PM filtrated in the trap, which was named as 'Active Exhaust Feeding Regeneration(AEFR) System' by its operation mechanism. Ceramic cordierite filter is a major component of the trap and susceptible to thermal shock. Therefore the system should be designed to reduce the peak temperature and temperature gradients in the trap ; these have been considered to be the main factors causing thermal shock of the filter during the regeneration. It uses the engine's exhaust gas partially for the regeneration of the ceramic filter. It controlled bypass flow rate of the engine's exhaust gas precisely to control the temperature of the gas entrained into the filter. Gas temperatures were measured inside filter, and the oxygen concentration at the outlet of the filter was also monitored during the regeneration to analyze the combustion process of the PM. The temperature distributions and temperature gradients in the filter during the regeneration varied widely according to the regeneration control schemes. Finally, this system shows relatively low peak temperature and temperature gradients in the filter during its regeneration. It is considered that this system uses a mew method to control the combustion rate of the PM, which is different from the methods used in the previous studies.

• Journal of Applied Biological Chemistry
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• 제54권2호
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• pp.114-119
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• 2011

황백으로부터 n-BuOH 추출물에서 약 50%의 hyaluronidase 저해효과가 있음이 확인되었다. n-BuOH 분획 농축물을 Sephadex LH-20 및 MCI gel CHP-20 column chromatography로 정제한 결과 저해활성을 가지는 Jatrorrhizine을 분리, 동정하였다. 황백추출물과 Jatrorrhizine은 모두 농도 의존적으로 NO 발현을 억제하였고, 100 ${\mu}g/mL$의 농도에서 60% 이상의 억제 효과를 나타내었다. 황백추출물과 Jatrorrhizine의 iNOS와 COX-2의 억제력을 살펴본 결과, 100 ${\mu}g/mL$의 농도에서 45% 및 29%의 저해효과를 나타내었다. 따라서 황백추출물 및 Jatrorrhizine은 LPS로 유도되어진 대식세포주인 Raw264.7 세포에서의 염증반응의 억제효과를 기대할 수 있었다.

• Environmental Engineering Research
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• 제19권4호
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• pp.331-338
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• 2014

Descriptive statistics methods were used to study the spatiotemporal variations and sources of ambient particulate matter ($PM_{10}$) in Luzhou, China. The analyzed datasets were collected from four national air quality monitoring stations: Jiushi (S1), Xiaoshi (S2), Zhongshan (S3), Lantian (S4) over the period of 2003-2012. This city was subjected serious $PM_{10}$ pollution, and the long-term annual average $PM_{10}$ concentrations varied from 76 to $136{\mu}g/m^3$. The maximum concentration was more than 3-fold of the annual average ($40{\mu}g/m^3$) issued by EPA-China for the ambient air quality. General temporal pattern was characterized by high concentrations in winter and low concentrations in summer, and general spatial gradient was in the reduction order of S2 > S4 > S3 > S1, which were both due to different particulate contributors and special meteorological conditions. The source apportionment indicated that vehicular emissions, road dusts, coal burning and chemical dusts were the major contributors of the identified $PM_{10}$ pollution, and the vehicular emissions and the road wear re-suspended particles dominated the heavy $PM_{10}$ pollution in recent years. Two other potential sources, agricultural and celebration activities could decrease the air quality in a short term. Finally, some corresponding suggestions and measures were provided to improve the air quality.

• Journal of Microbiology and Biotechnology
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• 제22권9호
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• pp.1193-1201
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• 2012

The analysis and quantification of ammonia-oxidizing bacteria (AOB) is crucial, as they initiate the biological removal of ammonia-nitrogen from sewage. Previous methods for analyzing the microbial community structure, which involve the plating of samples or culture media over agar plates, have been inadequate because many microorganisms found in a sewage plant are unculturable. In this study, to exclusively detect AOB, the analysis was carried out via denaturing gradient gel electrophoresis using a primer specific to the amoA gene, which is one of the functional genes known as ammonia monooxygenase. An AOB consortium (S1 sample) that could oxidize an unprecedented 100% of ammonia in 24 h was obtained from sewage sludge. In addition, real-time PCR was used to quantify the AOB. Results of the microbial community analysis in terms of carbon utilization ability of samples showed that the aeration tank water sample (S2), influent water sample (S3), and effluent water sample (S4) used all the 31 substrates considered, whereas the AOB consortium (S1) used only Tween 80, D-galacturonic acid, itaconic acid, D-malic acid, and $_L$-serine after 192 h. The largest concentration of AOB was detected in S1 ($7.6{\times}10^6copies/{\mu}l$), followed by S2 ($3.2{\times}10^6copies/{\mu}l$), S4 ($2.8{\times}10^6copies/{\mu}l$), and S3 ($2.4{\times}10^6copies/{\mu}l$).

• Korean Chemical Engineering Research
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• 제51권1호
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• pp.151-156
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• 2013

Polydimethylsiloxane (PDMS) 기반의 미세유체 시스템을 이용해 탄산칼슘의 결정화 실험을 수행하였다. 탄산칼슘의 결정화를 위한 다양한 반응방법 중 액체-액체 반응을 위해 염화칼슘 수용액과 탄산나트륨 수용액을 사용하였고 아스파르트산을 첨가하여 탄산칼슘 결정 중 베터라이트와 칼사이트의 생성에 어떤 차이를 보이는지 조사하였다. 그리고 탄산칼슘의 결정화 진행상황에서 결정핵 생성에 유리한 염화칼슘과 탄산나트륨의 비율을 조사하였다. 이를 위해 크리스마스트리 모양의 미세유체 반응기를 사용하여 채널 내부에 염화칼슘과 탄산나트륨의 농도구배를 형성하도록 하였다. 미세유체 결정화기 내부를 광학현미경으로 촬영한 결과, 탄산나트륨과 염화칼슘의 농도비가 2:1일 때 결정핵이 생성됨을 확인하였고 핵 생성 이후의 결정 성장 과정을 촬영하여 결정형태의 변화를 관찰하였다. 아스파르트산의 첨가 시에 결정핵 생성과 성장을 저해하며 전체 결정형태 중 베터라이트의 비율이 높아짐을 보였다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVII)
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• pp.651-654
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• 2005

10 g/L yeast extract, 20 g/L peptone, 20 g/L dextrose가 첨가된 YPD 배지를 이용하여 200 rpm, 30 $^{\circ}C$에서 24시간 배양한 Pichia pastoris X-33과 KM71H를 각각 대수 증식기에 시료를 채취하여 4000 g, 4 $^{\circ}C$에서 5분간 원심분리하여 펠릿만을 얻어 멸균된 증류수를 500 ${\mu}{\ell}$ 넣고 4000 g, 4 $^{\circ}C$에서 5분간 원심분리하여 2-3회 세포 내 단백질과 아미노산 분석에 이용하였다. HPLC는 OPA 시약을 만들어 4 $^{\circ}C$에서 24시간 안정화시켜 사용하였고, 용액 A와 B를 미리 준비하여 기울기용리로 30 $^{\circ}C$에서 1ml/min, Ex 330/ Em 420 nm에서 80분간 분석하였다.

• 대한한의학방제학회지
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• 제21권1호
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• pp.71-79
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• 2013

Objectives : Yijin-tang has been used in the treatment of gastrointestinal diseases such as irritable bowel syndrome, gastritis, and gastric ulcer. In this study, a high-performance liquid chromatography (HPLC) method was established for simultaneous analysis of six compounds, liquiritin, glycyrrhizin, hesperidin, 6-gingerol, homogentisic acid, and 3,4-dihydroxybenzaldehyde in Yijin-tang, a traditional Korean herbal medicinal preparation. Methods : A Gemini C18 column was used for the separation of six constituents at $40^{\circ}C$. The mobile phase using gradient elution consist of two solvent systems, 1.0% acetic acid in water (A) and 1.0% acetic acid in acetonitrile (B). The flow-rate was 1.0 mL/min and injection volume was $10{\mu}g$. The detector was a photodiode array (PDA) detector set at 254 nm and 280 nm. Results : The calibration curves of six compounds showed good linearity in various concentration ranges ($R^2{\geq}0.9997$). The limits of detection (LOD) and limits of quantification (LOQ) were 0.028-$0.192{\mu}g/mL$ and 0.093-$0.540{\mu}g/mL$, respectively. The RSD (%) of the intra and inter day validations were 0.03-0.84% and 0.05 -1.00%, respectively. Recovery was 96.14-01.90% and RSD (%) was less than 1.5%. Conclusions : The established simultaneous analysis methods will help management to improve the quality of Yijin-tang.