• 대한기계학회논문집B
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• 제34권5호
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• pp.505-513
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• 2010

삼지화염 구조는 화염 선단의 구조로서 다루어져 왔으며, 많은 연구자들에 의해 해석적인 방법과 실험적인 방법으로 연구가 되어왔다. 그러나 연료의 종류에 따른 가연한계의 차이가 삼지화염의 구조에 미치는 영향에 대한 연구는 깊이 있게 다루어지지 않았다. 본 연구에서는 화염 구조에 대한 비대칭 가연한계의 영향을 예혼합화염과 확산화염에 관한 몇 가지 층류화염 이론에 근거한 간단한 수치 기법을 통해 연구하였다. 고정된 유동장이 사용되었으며, 예혼합 화염 가지에서의 경계조건이 연계되었다. 예혼합 화염 후류의 확산화염의 형성과 소멸을 성공적으로 모사할 수 있었다. 비대칭 가연한계 조건과 열손실에 따른 확산화염의 변화가 연구되었다. 본 연구는 화염의 기초 구조에 대한 이해를 도울 수 있으며, 이후의 연구를 위한 기초로 활용될 수 있을 것이다.

• 대한수의학회지
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• 제45권4호
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• pp.569-574
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• 2005

Enzyme-linked immunosorbent assay (ELISA) for detection of antibodies to reticuloendotheliosis virus (REV) at single serum dilution was standardized. REV HI, one of the Korean field isolates, was inoculated into chicken embryo fibroblast (CEF) cells and was harvested from the culture fluids and cells after 10 to 12 days. Viruses were purified by centrifugation at the $107,000{\times}g$ for 12 hours on 20, 30, 45% (W/V) sucrose gradient. Virus specific fraction was collected and used as ELISA antigen. To standardize ELISA, the optimal concentration of coating antigen ($1{\mu}g/well$) and conjugate (1/1000) was determined by corrected OD (OD value of positive serum-OD value of negative serum) and P/N ratio (OD value of positive serum/OD value of negative serum). To calculate ELISA titer by measuring absorbance at 1/400 single serum dilution, serum titrations were carried out for various sample sera together with standard positive and negative sera. The observed titers of serum samples were plotted against sample/positive (s/p) ratios at 1/400 serum dilution. From the above data, the ELISA titers could be calculated by the equation of $log_{10}$ ELISA titer = 2.2763 ($log_{10}$ s/p) + 3.482 (r = 0.93). For evaluating the sensitivity, the standardized method were compared with conventional agar gel immunodiffusion (AGID) test method using serum samples collected from REV infected field chicken flocks. Fifty seven of 60 samples (95%) were positive for REV by ELISA, whereas only 11 (18.3%) samples were positive by AGID test. This results suggested that the ELISA tests developed in this study could be used for detection of antibodies to REV with high sensitivity.

• 한국축산식품학회지
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• 제30권6호
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• pp.923-929
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• 2010

Colostral whey prepared from colostrum (pooled from first six post-partum milkings) was heated for 10 min at $100^{\circ}C$ Heated colostral whey was incubated with 1% enzymes (protein equivalent basis) for 15, 30, 60, 90, and 120 min at $50^{\circ}C$. Papain, pepsin, trypsin, and alcalase produced different degrees of hydrolysis (DH), 10.66%, 12.42%, 10.83%, and 25.31%, respectively, at an incubation time of 120 min. The SDS-PAGE reveals that significant amounts of bovine serum albumin (BSA), ${\beta}$-lactoglobulin (${\beta}$-LG), and ${\alpha}$-lactalbumin (${\alpha}$-LA) survived papain digestion. In contrast, pepsin completely removed BSA but not ${\beta}$-LG present in heated colostral whey. Alcalase completely eliminated BSA, ${\beta}$-LG, and ${\alpha}$-LA. This differential hydrolysis was confirmed by reversed-phase HPLC analysis. Using ion-exchange chromatography, fraction-1 (F-1) was obtained from alcalase hydrolysate at a NaCl gradient concentration of 0.25 M. Reversed-phase HPLC chromatograms of alcalase F-1 showed numerous small peaks, which probably indicate that a variety of new peptides were produced. Iron content of alcalase F-1 was 28.94 ppm, which was the highest among all enzyme fractions, whereas iron content of colostral whey was 36.56 ppm. Main amino acids contained in alcalase F-1 were Thr (15.45%), Glu (14.12%), and Ser (10.39%). Therefore, alcalase can be used to generate good iron-binding peptides in heated colostral whey, and the resulting iron-binding peptides could be suitable as a value-added food ingredient for food supplements.

• 한국약용작물학회지
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• 제22권2호
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• pp.147-153
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• 2014

The Ponciri fructus immaturus (Poncirus trifoliata Rafinesque) has been used in oriental medicine for uterine contraction, stomachache, abdominal distension and cardiovascular diseases. Two main compounds, poncirin and naringin were successfully analyzed by high performance liquid chromatography (HPLC) and carried out method validation according to ICH guideline. A successful resolution and retention times were obtained with a $C_{18}$ reversed phase column, at an $1m{\ell}min^{-1}$ flow rate, with a gradient elution of a mixture of methanol, water and acetonitrile. Poncirin and naringin showed good linearity ($R^2$ > 0.999) in relatively wide concentration ranged. The recovery of each compound was 95.81 ~ 101.48% with R.S.D. values less than 1.0%. The application of ultrasound-assisted extraction was shown to be more efficient in extracting poncirin and naringin from Ponciri fructus immaturus. The predicted optimal poncirin and naringin yield were poncirin 2.15%, naringin 1.65% under an extraction temperature of $40^{\circ}C$, an extraction time of 10 min in a solvent of 70% methanol.

• 한국수산과학회지
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• 제47권6호
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• pp.770-775
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• 2014

The green microalga of the genus Nannochloropsis (class Eustigmatophyceae) is a leading candidate for biofuel production due to its ability to accumulate high oil content (28.7% of cellular ash-free dry weight). We investigated the anti-inflammatory and anticancer activities of sterol-rich fraction from nannochloropsis oculata n-hexane (NOH) extract after saponification of the microalga. Among the fractions with n-hexane, chloroform and ethyl acetate, the n-hexane fraction showed the highest anti-inflammatory activity in LPS-stimulated RAW 264.7 macrophage as well as anticancer activity against human leukemia HL-60 cells without the cytotoxity. And the sterol-rich fraction was obtained from the n-hexane fraction by open silica column under the gradient solvent condition with 100% hexane (1L), hexane : ethyl acetate (20 : 1, 10 : 1, 5 : 1, 1 : 1, v/v). Among the four fractions (NOH-1~4), especially NOH-1 contained the highest content of sterols. NOH1 showed the highest HL-60 (about 85%) and NO inhibitory activities at the concentration of $100{\mu}g/mL$. These results demonstrated that the sterol-rich fraction from N. oculata might be a useful candidate as anti-inflammatory and anticancer agents for anti-inflammatory and anticancer activity.

• Korean Chemical Engineering Research
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• 제52권1호
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• pp.68-74
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• 2014

해수-담수 염도 차 발전을 위한 압력지연삼투(pressure-retarded osmosis: PRO) 시스템의 나권형(spiral wound) 모듈에서 공급채널과 유도채널 사이의 입구 압력차의 영향이 수치적으로 연구되었다. 그리하여 막을 통한 물과 용질-플럭스들의 변화와 전력이 예측되었다. 막을 통한 물-플럭스의 크기는 두 채널 간 입구 압력차가 증가할수록 x축 방향으로 감소하고 y축 방향으로 증가하였다. 반면에 막을 통한 용질-플럭스의 크기는 반대의 경향을 보였다. 공급채널 내 유체의 농도는 y축 방향으로 크게 증가하였고, 유도채널 내 농도는 x축 방향으로 크게 감소하였다. 본 시스템에서 입구 압력차가 1~11 atm일 때 공급채널 내 유량은 8~13% 가량 감소하였고, 유도채널 내 유량은 그만큼 증가하였다. 전력밀도는 입구 압력 차가 증가할수록 증가하다가 감소하였다.

• Bulletin of the Korean Chemical Society
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• 제33권1호
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• pp.177-182
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• 2012

A new composition of standardized Scutellariae Radix extract (HPO12) was developed for treatment of Alzheimer's disease. For the preclinical pharmacokinetic study of HPO12, a rapid, sensitive, and selective LCMS/MS method was developed and validated for the simultaneous determination of 4 bioactive compounds, baicalein, baicalin, wogonin, and wogonoside. After extraction with ethylacetate, chromatographic analysis was performed on a Thermo $C_{18}$ column ($150mm{\times}2.1mm$, $3{\mu}m$) with a mobile phase consisting of 0.1% formic acid (A) and 0.1% formic acid in 95% acetonitrile (B) by using gradient elution at a flow rate of $250{\mu}L/min$. Analytes introduced to a mass spectrometer were monitored by multiple reaction monitoring (MRM) in positive ion mode. Using $25{\mu}L$ of plasma sample, the method was validated over the following concentration ranges: 25-5000 ng/mL for baicalein, 20-40000 ng/mL for baicalin, 1-1000 ng/mL for wogonin, and 5-10000 ng/mL for wogonoside. The intra- and inter-day precision and accuracy of the quality control samples at the 4 concentrations showed $\leq$ 13.7% relative standard deviation (RSD) and 86.6-105.5% accuracy. The method was successfully applied to determine the concentrations of baicalein, baicalin, wogonin, and wogonoside in rat plasma after intraperitoneal and oral administrations of HPO12.

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3284-3288
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• 2013

This paper describes first development and validation of pentafluorophenylprophyl ligand-based liquid chromatography coupled to tandem mass spectrometry (PFPLC-MS/MS) method to determine metformin, a highly polar compound, in human plasma. Metformin and Phenformin (internal standard) were extracted from human plasma 50 ${\mu}L$ with a single-step protein precipitation. The chromatographic separation was performed using a linear gradient elution of mobile phase involving 5.0 mM ammonium formate solution with 0.1% formic acid (A) and acetonitrile (B) over 3.0 min of run time on a Phenomenex Luna PFP column. The detection was performed using a triple-quadrupole tandem mass spectrometer (Waters Quattro micro) with electrospray ionization in the mode of positive ionization and multiple-reaction monitoring (MRM). The developed method was validated with 5.0 ng/mL of lower limit of quantification (LLOQ). The calibration curve was linear over 5-3000 ng/mL of the concentration range ($R^2$ > 0.99). The specificity, selectivity, carry-over effect, precision, accuracy and stability of the method met the acceptance criteria. The method developed in this study had had rapidness, simplicity and ruggedness. The reliable method was successfully applied to high throughput analysis of real samples for a practical purpose of a pharmacokinetic study.

• 한국전산구조공학회논문집
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• 제20권4호
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• pp.501-507
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• 2007

본 연구의 전편에서는 이동최소제곱 유한차분법을 이용한 고체역학문제의 정식화 과정이 소개되었다. 후편에서는 수치예제를 통해 이동최소제곱 유한차분법의 정확성, 강건성, 효율성을 검증했다. 탄성론 문제의 해석을 통해 개발된 해석기법의 우수한 수렴률을 확인했다. 탄성균열문제에 적용하여 간편한 불연속면 모델링이 가능하고, 적응적 절점배치를 통해 특이 응력해를 정확하고 효율적으로 계산할 수 있음을 보였다. 국소화 밴드문제 해석결과를 통해 변위나 응력이 급격하게 변화하는 특수문제에 대한 정확성과 효율성을 확인했으며, 본 해석기법이 다양한 특수 공학적 문제로 확장될 수 있을 것으로 기대된다.

• Ocean and Polar Research
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• 제27권4호
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• pp.381-395
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• 2005

The spatial distributions of macrobenthic communities in Masan Bay were investigated during summer and winter, 2004. A total of 104 species were sampled with mean density of $448ind./m^2$ and biomass of $77.1g/m^2$ in winter. In summer, a total of 107 species occurred with $485ind./m^2$ and a biomass of $94.5g/m^2$. The most dominant species in winter were Paraprionospio pinnata (24.2%) among polychaetous worms and Theora fragilis (14.1%) among molluscs, but they were replaced in summer by Prionospio chirrifera (20.4%) and Lumbrineris longifolia (14.5%). The difference in species composition and abundance of benthic communities between the two seasons was due to the hypoxia in the bottom layer of the inner bay during summer, which defaunated the macrofauna of the sediments. In the winter when DO concentration increased to normoxia, the pelagic larvae of benthic fauna settled in the soft sediments, but there was a spatial gradient in values of total biomass, density, and H' and benthic pollution index (BPI): higher values were found toward the mouth of the bay. The multivariate analyses like the cluster analysis and MDS ordination showed that Masan Bay could be divided into two or four stational groups in winter and summer whether the hypoxia occurred or not. Group I consisted of sites at the inner bay and central area and Group II, sites at the bay mouth. In summer the inner bay area could be further divided into the shallow impoverished area and the deeper abiotic one.