• Journal of the Society of Cosmetic Scientists of Korea
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• v.22 no.2
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• pp.153-160
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• 1996

A novel simple method to detect vitamins in cosmetic products by gas chromatography-mass spectrometry(GC-MS) has been developed. Three vitamins(panthenol, cholecalciferol and tocopherol) were used for this study. Vitamins were prepared by dissolving in tetrahydrofuran(THF), and silylated with bis-trimethylsilyltrifluoroacetamide-trichloromethylsilane(BSTFA). Silated vitamins were separated on a fuses-silica capillary column coated with DB-5. The identification of each vitamin was accomplished by retention time and mass spectrum library search with a computer, and the quantitation was made in the selected-ion monitoring(SIM) mode of GC-MS. SIM mode had given sensitivity to determine 50pg of panthenol, 285pg of cholecalciferol and 130pg of tocopherol. Linearity was maintained over the range 0.005-0.20% for each vitamin. Each cosmetic product(i.e. hair tonic and lotion) was found to contain amounts of the vitamins. This method was sensitive and gave 77.5-99.9% recovery of each vitamin from these cosmetic products. From these results, we concluded that silylation with BSTFA followed by GC-MS analysis allows the simple, covenient and exact determination of panthenol, cholecalciferol and tocopherol.

• Proceedings of the KAIS Fall Conference
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• 2001.05a
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• pp.290-291
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• 2001

The relationship between velocity, viscosity, diffusion coefficient, mass transfer coefficient and characteristic length and mass transfer data can be correlated by dimensionless relationship in electrolytic process. The performance of dyestuff removal was decreased as the flow rate of electrolyte was increased. It was due to the effect of retention time decreasing was superior to that of turbulent inlet mixing. Sh/Sc$\^$1/3/ vs Re plot for Al flat electrode did not showed the general tendency of the relationship between Sh/Sc$\^$1/3/ and Re. It can be thought that flow rate was not sufficiently high to increase the effect of mixing.

• KSBB Journal
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• v.13 no.3
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• pp.268-271
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• 1998

Bacteriorhodopsin in the purple membrane (PM) of halobacteria has recently been attracting much attention to be used as a component of molecular electron device and optical computers. In order to increase the productivity of bacteriorhodopsin in high cell density cultures of Halobacterium halobium R1, an internal membrane cell-retention bioreactor system was employed. As a result, the production of cell mass at OD660 of 12 and of bacteriorhodopsin at 125-130 mg/L were obtained using the internal membrane bioreactor system at a dilution rate of 0.066 hr-1. The productivity achieved by the internal membrane system (0.7 mg/L$.$hr) was 3.5-fold higher than that obtained by the corresponding batch cultivations (0.2 mg/L$.$hr).

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.3
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• pp.74-80
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• 2005

The compositions of residual extractives in woodmeal, unbleached and oxygen-delignified aspen kraft pulps were investigated with gas chromatography(GC) and gas chromatography-mass spectrometry (GC-MS) with focus on fate of extractives in kraft pulping and oxygen delignification. Steryl esters and shorter retention time (shorter than palmitic acid) extractives were main extractives in aspen woodmeal. Shorter retention time extractives were well removed in kraft pulping. Sterol esters were hydrolyzed to sterols and fatty acids. Sterols and fatty acids were two major extractives classes in unbleached kraft pulps. Linoleic acid was main fatty acids in unbleached pulps compared with palmitic acid which is generally found in aspen woodmeal. Sterolsand fatty acids were also two major extractives classes in oxygen-delignified kraft pulps. However, linoleic acid was well removed in oxygen delignification.

• Nuclear Engineering and Technology
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• v.52 no.11
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• pp.2499-2510
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• 2020

We performed 3-D (3-dimensional) IVR (In-Vessel Retention) natural convection experiments simulating the oxide layer in the three-layer configuration, varying the aspect ratio (H/R). Mass transfer experiment was conducted based on the analogy to achieve high Ra_H's of 1.99 × 10¹²-6.90 × 10¹³ with compact facilities. Comparisons with 2-D (2-dimensional) experiments revealed different local heat transfer characteristics on upper and lower boundaries of the oxide layer depending on the H/R. For the 3-D shallow oxide layer, the multi-cell flow patterns appeared and the number of cells was considerably increased with the H/R decreases, which differs with the 2-D experiments that the number of cells was independent on H/R. Thus, the enhancement of the downward heat transfer and the mitigation of the focusing effect were more noticeable in the 3-D experiments.

• YAKHAK HOEJI
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• v.39 no.3
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• pp.283-288
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• 1995

Rapid gas chromatographic profiling method was applied to saliva from healthy subjects for the analysis of free organic acids. Saliva samples were first saturated with NaHCO$_{3}$ and extracted with diethyl ether. The aqueous phase was solid-phase extracted using Chromosorb P as the adsorbent and diethyl ether as the eluent after the acidification and NaCl saturation, followed by triethylamine treatment. The resulting tiiethylammonium salts of acids were directly converted into stable tert.-butyl-dimethylsflyl derivatives, with subsequent analysis by dual-capiuary column gas chromatography and gas chromatograpy -mass spectrometry. From the ten saliva samples studied, twenty eight free organic acids including various fatty acids, hydroxy acids, dicarboxylic acids, md aromatic acids were tentatively identified. Among the acids identified , the concentration of lactic acid was highest for five saliva samples while $\alpha$-hydroxyisocaproic acid was most abundant for me sample, and succinic acid and glycolic acid for two samples. respectively. When the GC profiles were simplified to the corresponding acid retention index spectra of bar graphical form, they presented characteristic patterns for each individual.

• Nuclear Engineering and Technology
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• v.45 no.3
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• pp.335-346
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• 2013

The Critical Heat Flux (CHF) of water with dispersed alumina nanoparticles was measured for the geometry and flow conditions relevant to the In-Vessel Retention (IVR) situation which can occur during core melting sequences in certain advanced Light Water Reactors (LWRs). CHF measurements were conducted in a flow boiling loop featuring a test section designed to be thermal-hydraulically similar to the vessel/insulation gap in the Westinghouse AP1000 plant. The effects of orientation angle, pressure, mass flux, fluid type, boiling time, surface material, and surface state were investigated. Results for water-based nanofluids with alumina nanoparticles (0.001% by volume) on stainless steel surface indicate an average 70% CHF enhancement with a range of 17% to 108% depending on the specific flow conditions expected for IVR. Experiments also indicate that only about thirty minutes of boiling time (which drives nanoparticle deposition) are needed to obtain substantial CHF enhancement with nanofluids.

• Korean journal of food and cookery science
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• v.2 no.2
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• pp.16-20
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• 1986

The major pungent component from Korean radish roots was purified by reverse phase high performance liquid chromatography (RPHPLC), and characterized as 4-methylthio-3-butenyl isothiocyanate on the basis of the sensory test (pungency), UV spectrum and mass spectrum analysis. The purified isothiocyanate moved as a single peak(retention time, 5.2 min) in RP-HPLC analysis, and as a single spot(Rf, 0.9) in TLC analysis.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.19 no.1
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• pp.36-43
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• 2023

Lots of researches have been conducted on in-vessel retention (IVR) to prevent or mitigate severe accident in nuclear power plants. Various methodologies were proposed and the external reactor vessel cooling was selected as a part of promising IVR strategy. In this study, the strategy is strengthened by enhancing the natural circulation performance through the adoption of insulation in the reactor cavity. A thermal analysis was carried out based on an assumed accident scenario and its results were used as boundary conditions for subsequent seven flow analysis cases. By comparing the natural circulation performance, effects of annular gaps and insulation shapes on the mass flow rate and flow velocity were quantified. The improvement in cooling performance can be reflected in actual design via detailed assessment.

• Mass Spectrometry Letters
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• v.2 no.2
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• pp.37-40
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• 2011

Saccharin is a commonly used artificial sweetener in foodstuffs. However, for its carcinogenic dispute, it has been regulated by government bodies. In this study, isotope dilution mass spectrometry (ID-MS) was introduced for the accurate quantification of saccharin. To employ ID-LC/MS, we obtained its isotope analogue, $^{13}C_1$-sodium saccharin, by customized synthesis. Samples were spiked with $^{13}C_1$-sodium saccharin and analyzed with LC/MS in negative mode. Chromatographic conditions were optimized for the adequate chromatographic retention and separation of saccharin with a $C_{18}$ column. MS was operated with electrospray ionization by the selected ion monitoring (SIM) mode of $[M-H]^-$ for saccharin (m/z 182) and $[M-Na]^-$ for its isotope analogue (m/z 183). To validate the ID-LC/MS method for accurate measurement, we prepared a batch of a candidate material by sortifying quasi-tea-drinks with saccharin and analyzed samples gravimetrically fortified in various levels of concentration. The repeatability and reproducibility of this method was tested by analyzing the reference material. Result show that ID-LC/MS is a reliable method for the quantitative analysis of saccharin.