• YAKHAK HOEJI
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• v.60 no.3
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• pp.112-117
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• 2016

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the determination of caffeine in forensic aqueous sample. The centrifuged sample ($100{\mu}l$) was diluted 50-fold with distilled water. The diluted sample ($400{\mu}l$) was then diluted further with $200{\mu}l$ of 0.1% formic acid solution and $400{\mu}l$ of acetonitrile containing 500 ng of caffeine-(3-methyl-$^{13}C_3$) prior to LC-MS/MS analysis. The mobile phase was composed of 0.1% formic acid in distilled water (A) and acetonitrile (B). Chromatographic separation was performed by using a Zorbax SB-C18 ($100mm{\times}2.1mm$ i.d., $3.5{\mu}m$) column and caffeine was eluted within 1.1 min. Linear least-squares regression with a 1/x weighting factor was used to generate a calibration curve with the coefficients of determination ($r^2=0.9983$). The lower limit of quantification was $25ng/ml$ for the analyte. The process efficiency was 98.6~100.1%. Intra- and inter-day precisions were not more than 2.1% and 1.7%, while intra- and inter-day accuracies were ranged from -6.8 to 4.5%, respectively. The suitability of the method was examined by analyzing unknown forensic aqueous samples.

• YAKHAK HOEJI
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• v.55 no.1
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• pp.64-68
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• 2011

In this study, a high performance liquid chromatography-diode array detector method was established, for simultaneous determination of three compounds, berberine, palmatine and geniposide in Hwangryunhaedok-tang, To develop and validate method, $C_{18}$ column (5 ${\mu}M$, 4.6 mm${\times}$250 mm) was used with gradient mobile phase, water containing 0.1% trifluoroacetic acid (TFA) and MeOH at the column temperature of $30^{\circ}C$. UV wavelength was set at 230 and 280 nm. Validation of the chromatography method was evaluated by linearity, precision and accuracy test. Calibration curve of standard components showed good linearity ($R^2$ > 0.9999). The limits of detection (LOD) and limits of quantification (LOQ) varied from 0.05 to 0.17 ${\mu}g/ml$ and 0.15 to 0.53 ${\mu}g/ml$, respectively. The relative standard deviations (RSDs) data of intra-day and inter-day test were in less than 2.99% and 1.90%, respectively. The results of the accuracy test were in the range of 98.36 to 102.52% with RSDs values 0.32 to 1.98%. The results of validation indicated that this method was a very accurate and sensitive assay.

• Bulletin of the Korean Chemical Society
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• v.24 no.3
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• pp.377-383
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• 2003

Physicochemical properties of a series of PC monolayers with different alkyl chains (C24, C20, C16, and C8), at the air/water interface were investigated. The surface pressure is influenced mainly by the hydrophobicity of the PCs, which is confirmed by the curve shape and the on-set value of π-A isotherms at the air/water interface by increasing the number of alkyl chain. The on-set values of surface pressure were 125 Ų/molecule for DOPC(C8), 87 Ų/molecule for DPPC(C16), 75 Ų/molecule for DAPC(C20), and 55 Ų/molecule for DLPC(C24), respectively. The orientations of alkyl chains at the air/water interface are closely connected with the rigidity of the monolayers, and it was confirmed by the tendency of monolayer thickness in ellipsometry data. The temperature dependence of a series of PCs shows that the surface pressure decreases by increasing temperature, because the longer the alkyl chain length, the larger the hydrophobic interaction in surface pressure. The temperature effects and the conformational changes of unsaturated and saturated PCs were confirmed by the computer simulation study of the cis-trans transition with POPC and DPPC(C16). The cistrans conformational energy difference of POPC is 62.06 kcal/mol and that of DPPC(C16) is 6.75 kcal/mol. Due to the high conformational energy barrier of POPC, phase transition of POPC is limited in comparison with DPPC(C16).

• The Korean Journal of Mycology
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• v.14 no.1
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• pp.43-47
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• 1986

Among the representative phenolic compounds in relation to lignin derivatives and protein synthesis inhibitors, the most effective inducer for the extracellular polyphenol oxidase (PO) of Lentinus edodes JA01 was gallic acid and ferulic acid for Pleurotus ostreatus. Optimum concentration of these inducers was 2.0 mM and 1.0 mM, respectively. Addition of gallic acid after two days culture had the best effect on production of PO enzyme of L. edodes JA01 and for P. ostreatus, and addition of ferulic acid after three days culture had the best effect. Also, in case of L. edodes JA01, polyphenol oxidase activity was parallel to growth curve, whereas the maximum enzyme activity of P. ostreatus was shown at exponential growth phase and declined thereafter.

• Journal of the Korean Magnetics Society
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• v.16 no.1
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• pp.14-17
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• 2006

[ $AIFeO_3$ ]has been studied by x-ray diffraction (XRD), vibrating sample magnetometer, Mossbauer spectroscopy. The crystal structure is found to orthorhombic with the lattice parameters being $a_0=4.983\;{\AA},\;b_0=8.554\;{\AA},\;c_0=9.239\;{\AA}$, Magnetic hysteresis curve for $AIFeO_3$ showed weakly ferromagnetic phase at room temperature and a asymmetric shape dependent on the direction of applied field at low temperature. The Curie temperature determined by the temperature dependence of magnetization is 250 K. Mossbauer spectra of $AIFeO_3$ have been taken from 4.2 K to 295 K. Isomer shift at room temperature are found to be $0.11\~0.32\;mm/s$, which is consistent with ferric state. The absorption lines widths become broader with increasing temperature, which is attributed to the Fe ions distribution of each cation site and anisotropy energy difference of each sublattice.

• Food Science of Animal Resources
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• v.40 no.5
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• pp.746-757
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• 2020

Enterotoxigenic Escherichia coli (ETEC) is the major pathogenic E. coli that causes diarrhea and edema in post-weaning piglets. In this study, we describe the morphology and characteristics of ØCJ19, a bacteriophage that infects ETEC, and performed genetic analysis. Phage ØCJ19 belongs to the family Myoviridae. One-step growth curve showed a latent phase of 5 min and burst size of approximately 20 phage particles/infected cell. Phage infectivity was stable for 2 h between 4℃ and 55℃, and the phage was stable between pH 3 and 11. Genetic analysis revealed that phage ØCJ19 has a total of 49,567 bases and 79 open reading frames (ORFs). The full genomic sequence of phage ØCJ19 showed the most similarity to an Escherichia phage, vB_EcoS_ESCO41. There were no genes encoding lysogeny, toxins, virulence factors, or antibiotic resistance in this phage, suggesting that this phage can be used safely as a biological agent to control ETEC. Comparative genomic analysis in terms of the tail fiber proteins could provide genetic insight into host recognition and the relationship with other coliphages. These results showed the possibility to improve food safety by applying phage ØCJ19 to foods of animal origin contaminated with ETEC and suggests that it could be the basis for establishing a safety management system in the animal husbandry.

• Fire Science and Engineering
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• v.33 no.4
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• pp.50-58
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• 2019

The prediction performance of B-RISK was evaluated for the fire behaviors of combustibles in a compartment using Fire Dynamics Simulator (FDS). First of all, to predict the heat release rate (HRR) for two combustible sets, the HRR for one combustible set and the design fire curve were used as input values for B-RISK. Comparing results of B-RISK calculations with experimental data for two combustible sets, it was found that B-RISK results predicted insufficiently for fire growth rate of experimental data but there was good agreement for maximum HRR and total HRR with the experimental data. And the B-RISK results were used for input values of FDS to evaluate the fire behaviors of B-RISK results. Comparing results of FDS calculations with experimental data, the simulation results showed that the temperature and concentrations of O₂, CO₂ in the fire growth phase were different from the experimental data. However, when using the B-RISK result for percentile 70%, the simulation results sufficiently predicted the overall fire behaviors.

• Journal of Environmental Science International
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• v.24 no.4
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• pp.541-547
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• 2015

Formation of disinfection by-products (DBPs) including trihalomethans (THMs) and haloacetic acids (HAAs) from chlorination of six different species (Chlorella vulgaris, Scenedesmus sp., Anabaena cylindrical, Microcystis aeruginosa, Asterionella formosa and Aulacoseira sp.) of algal extracellular organic matter (EOM). The EOM characteristics evaluation of six algal species reaching at the stationary phase in the growth curve showed most of its SUVA254 showed below 1 and this means hydrophilic organic matter is much higher than hydrophobic organic matter. Chloroform formation potential (CFFP), dichloroacetic acid formation potential (DCAAFP) and trichloroacetic acid formation potential (TCAAFP) were mainly composed of THMFP and HAAFP in the EOM of various algal species. In the case of THMFP/DOC and HAAFP/DOC values, EOM of blue-green algae has appeared highest and EOM of green algae and diatom in order. THMFP/DOC was higher than HAAFP/DOC in EOM of blue-green algae. In comparison of formation potential by unit DOC composed of HAAFP in algal species EOM, DCAAFP/DOC was 1.5 times to 7.5 time higher than TCAAFP/DOC in the EOM of blue-green algae, while DCAAFP/DOC was found to be relatively high compared to TCAAFP/DOC in the EOM of green algae and diatom.

• The Korea Journal of Herbology
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• v.32 no.1
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• pp.55-62
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• 2017

Objectives : Crataegi Fructus has been used as traditional medicines for more digestion action, amenorrhea due to blood stasis, and hyperlipemia. The aim of this study was to compare of Crataegi Fructus in South Korea collected during three years according to the standards in monographs of the Korean Pharmacopoeia Eleventh edition (KP 11). Methods : Crataegi Fructus was carried out identification test (Qualitative reaction, Thin layer chromatography), heavy metal test, and total ash registered at KP. Add to we tested loss on dry, contents of ethanol-soluble extracts, and HPLC profiling. Results : Identification test (TLC) was on comparing with ursolic acid standard solution in $R_f$ value, all samples showed red purple spot ($R_f$ value 0.9). Ursolic acid spot in $R_f$ value 0.35 showed by changing mobile phase condition. Heavy metals showed contents for Pb, Cd, As, and Hg range of 0.0 ~ 0.5 ppm, 0.0 ~ 0.2 ppm, 0.0 ~ 0.3 ppm, and 0.0 ~ 0.1 ppm. Loss on drying was ranged from 5.5 to 11.9 %, total ash was between the range 2.7 ~ 4.0 %. Contents of ethanol-soluble extracts was ranged from 17.8 to 44.9 %. The content of chlorogenic acid was ranged from 0.0 to 0.1 % based on the chlorogenic acid standard curve. Conclusion : We have verified the current specification standard of Crataegi Fructus and standard that is not set. We hope that it will help the standardization of Crataegi Fructus.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.815-826
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• 2009

The paper presents a case study addressing the design and construction aspects for DCM(Deep Cement Mixing) method employed as the foundation of a caisson type breakwater with heavy weight(10,700 ton/EA) and a high design wave height($H_{1/3}$=8.7m). The DCM was designed for the project(Ulsan New Port North Breakwater Phase 1) by optimizing the pattern of DCM columns with a combination of short and long columns (i.e., block type(upper 3m)+wall type(lower)) and considering overlapped section between columns as a critical section against shear force where the coefficient of effective width of treated column($\alpha$) was estimated with caution. It was shown that the value can be 0.9 under the condition with the overlapped width of 30cm. In addition to that, a field trial test was performed after improving conventional DCM equipment (e.g., mixing blades, cement paste supplying pipes, multi auger motor, etc.) to establish a standardized DCM construction cycle (withdrawal rate of mixing blades) which can provide the prescribed strength. The result of the field strength test for cored DCM specimens shows that the averaged strength is larger than the target strength and the distribution of the strength(with a defect rate of 7%) also satisfies with the quality control normal distribution curve which allows defect rate of 15.9%.