• YAKHAK HOEJI
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• v.5 no.1
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• pp.24-26
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• 1960

Micro-determination of Lead by Dithizone Method was studied as follows: 1) Max. absorption wave length of Dithizone-pb complex in CC $l_{4}$ soln. is 510m.mu., 2) at the range of 5.gamma.-120.gamma. pb content, Bourguer-Beer's law hold good, 3) co-existence of F $e^{++}$ Z $n^{++}$, and C $u^{++}$ interfere.rfere.

• Journal of the Korean Chemical Society
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• v.37 no.5
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• pp.496-502
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• 1993

Spectrophotometric determination of rare earth elements with MTB and the composition ratio were investigated in the presence of surfactants of cetylpyridinium chloride (CPC), Triton X-100, dodecyltrimethylammonium bromide (DTMAB) and cetyltrimethylammonium bromide (CTMAB) at pH 6.5. The colour development between MTB and rare earths in the presence of cationic surfactants was very stable and more sensitive than that in the absence of surfactants. The largest absorbance increase was provided by CPC, which was therefore chosen for determination of rare earth elements. REE-MTB-CPC complex has absorption maxima at 650 nm and obeys the Beer's law in the range of 0∼100 ng/ml. Molar absorptivity is $6.6{\sim}9.4{\times}10^4\;mol^{-1}l\;cm^{-1}$.

• Journal of the Korean Chemical Society
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• v.51 no.4
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• pp.331-338
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• 2007

A rapid, simple and sensitive spectrophotometric method was developed for the determination of cobalt(II) using 2-hydroxy-3-methoxy benzaldehyde thiosemicarbazone (HMBATSC) as a analytical reagent. The metal ion in aqueous medium forms a brown coloured complex with HMBATSC at pH 6.0. The complex has two absorption maxima at 375 nm and 390 nm. At 375 nm, the reagent shows considerable absorbance, while at 390 nm the reagent does not shows appreciable absorbance. Hence, analytical studies were carried out at 390 nm. Beer's law is obeyed in the range of 0.059-2.357 μg ml-1 of Co(II). The molar absorptivity and Sandall's sensitivity of the method are 2.74×104 l mol-1 cm-1 and 0.0024 μg cm-2 respectively. The interference of various diverse ions has been studied. The complex has 1:2 [Co(II)- HMBATSC] stoichiometry. A method for the determination of cobalt(II) by second order derivative spectrophotometry has also been proposed. The proposed methods were applied for the determination of cobalt(II) in alloy steels, vitamin B12 and in some biological samples.

• Journal of the Korean Chemical Society
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• v.44 no.4
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• pp.322-327
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• 2000

A new absorption spectrometric method for the determination of the Cr$_2O_7^{2-}$ ionin acidic media has been developed. The new method is based on the oxidation-reduction reaction of the HCr$O_4^-$ ion with H$_2$O$_2$forming a deep blue CrO(O$_2$) $_2$ andis coupled with a technique of flow injection analysis(FIA). The new method provides a linear calibration curve which accurately follows the Beer's law over a wide range of the analytical concentrations(2.0 ${\times}$ $10^{-6}$M~8.0 ${\times}$ $10^{-3}$M) of K$_2$Cr$_2$O$_2$. The sensitivity of the new method is approximately two times greater than the current method and the effects of the interfering substances such as V, Co, Ni, Fe, and Mn are almost negligible except Cu.

• Journal of Environmental Health Sciences
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• v.46 no.1
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• pp.65-77
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• 2020

Objectives: This study investigated the average number of drinkers in Korea, the number of high-risk drinkers, the average amount of alcohol consumed by high-risk drinkers, and the types of alcohol consumed according to the characteristics of the group of dependent drinkers. Methods: The results were obtained by analyzing the following data: The Global Status Report on Alcohol and Health; Country Profile 2014; WHO Country Profile 2014; Korea National Health and Nutrition Examination Survey 2014, Korean Statistical Information Service; National Tax Statistics-Liquor Tax; Gallup Drinking Frequency Survey 2015 Results: This study found that a large proportion of drinkers in Korea are already high-risk drinkers, and even among drinkers, alcohol consumption was highly biased. It was reported that 49.8% of men in the problem, abuse, and dependence groups accounted for 92.4% of total alcohol consumption among the male population. Notably, the 9.6% of men making up the dependent group consumed more than 30% of the alcohol ingested among males. Women had significant variations within groups that were considered high-risk and exhibited a large share of alcohol consumption in the problem (10.0% of the female population), abuse (1.8% of the female population), and dependence (1.5% of the female population) groups, constituting 72.8% of total alcohol consumption. The average amount of alcohol consumed by drinkers in Korea seems to have exceeded the level of intake by high-risk groups. Alcohol-dependent groups consumed 900.7 mL of soju, 405.2 mL of table wine, and 2,043.8 mL of beer, which is very similar to the consumption average of 2,031 mL of beer and 895.2 mL of soju in the drinking group. Conclusion: It has been shown that men's dependence on alcohol is serious, and it is possible to infer that alcohol consumption in some vulnerable groups is very high. As the average alcohol intake among alcohol-dependent groups and ordinary drinkers is very similar, it is highly likely that the drinker is an alcohol-dependent consumer in Korea.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.3
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• pp.259-264
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• 1990

Improvement in production, post-harvest processing, quality grading, storage and malting process of malting barley is apparantly necessary to upgrade the beer quality and to reduce the losses in malt production. To establish the bases for the improvement, the present study examined the effect of storage conditions on the germinability of malting barley by quality grade of barley at production, and feasibility of mixing different varieties and different quality grades. Germinability of malting barley decreased significantly after 13 months of storage in the off-grade grain storage house, and after 15 months in the 1st grade storage house under the climate of Korea. Malting barley that was off-grade at harvest deteriorated faster than the 1st grade during 5 years storage under ordinary conditions. Mixing of varieites, different grain-quality grades or differently stored barleys seems to increase variability in germinating forces and germinability, resulting in uncontrollable malting processes and poor quality of malts and beer.

• Analytical Science and Technology
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• v.9 no.3
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• pp.244-252
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• 1996

Spectrophotometric properties of lanthanide complexes with methylthymol blue(MTB) and cetyltrimethylammonium bromide(CTAB) were studied and also lanthanide(III) ions were determined by flow injection analysis on the base of the above results. The absorption maxima of lanthanide(III)-MTB complexes in the presence of CTAB are 635nm with molar absorptivity of $4.51{\sim}6.11{\times}10^4Lmol^{-1}cm^{-l}$ at pH 5.8. The mole ratio of lanthanide(III) complexes with MTB is 1:2 in the presence of CTAB. The calibration curves of lanthanide(III) ions obey the Beer's law in the range of 0.1 to 0.4ppm under the optimum condition. The samples throughput was ca. $60hr^{-1}$. The interfering effect of some cations and anions was investigated. The ligand anions such as tartrate and citrate, many transition and rare earth elements interfered severely and must be removed before the determination of lanthanide(III) ions.

• Journal of Microbiology and Biotechnology
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• v.16 no.3
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• pp.480-483
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• 2006

Ethyl carbamate, a by-product produced naturally during fermentation and contained in fermented foods and beverages, is a carcinogen. Thus, due to the high consumption of alcoholic beverages in Korea, the ethyl carbamate concentrations in popular alcoholic beverages were determined, and the daily intake of ethyl carbamate through alcoholic beverages was estimated. The major Korean alcoholic beverages, Soju, beer, and Takju, with the highest market share were sampled and their ethyl carbamate concentrations determined by GC/MS/SIM. The ranges of ethyl carbamate contained in Soju, beer, and Takju was 0.83-10.07, 0.45-0.77, and 0.40-0.93 ppb, respectively. These results and data on the average daily intake of alcoholic beverages were then used to calculate the average and maximum estimated daily intakes (EDI) of ethyl carbamate through alcoholic beverages. As a result, a relatively high EDI of ethyl carbamate through alcoholic beverages was found for Korean males over 30 years old, indicating the need to reduce the ethyl carbamate content in alcoholic beverages.

• Korean Journal of Food Science and Technology
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• v.49 no.1
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• pp.35-43
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• 2017

The sensory characteristics of 12 commercial top-fermented beers were determined by sensory descriptive analysis. Beer samples were also analyzed for soluble solids, titratable acidity, pH, reducing sugar content, bitterness unit (BU), turbidity, hunter color values, amino acid content, total phenolic content, and DPPH radical scavenging activity. Five appearance, nine aroma, six flavor/taste, and four mouth-feel related sensory attributes were evaluated by a panel of nine judges. As the result of three way analysis of variance of descriptive data, all sensory attributes except "cereal" aroma and "salty" taste showed significant differences among the beers (p<0.05). Based on the principal component analysis of the descriptive data, samples were primarily separated by first and second principal components, which accounted for 78% of the total variance between the beers with high intensities of "yellow color", "caramel aroma", and "barley taste" versus "hop aroma", "sour", and "citrus aroma". In the correlation analysis between the sensory terms and physicochemical parameters, BU, total phenolic content, titratable acidity, soluble solids, and yellowness ($b^*$) showed significant positive correlations with citrus aroma, pineapple aroma, and fresh aroma characteristics.

• Analytical Science and Technology
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• v.7 no.3
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• pp.277-284
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• 1994

The spectrophotometric determination of rare earth elements with XO was investigated in the presence of cetylpyridium chloride(CPC), dodecyltrimethylammonium bromide(DTMAB), cetyltrimetylammonium bromide (CTMAB), Triton X-100 at pH 6.2. The complex between XO and rare earth elements in the presence of cationic surfactants was very stable and more sensitive than in the absence of surfactants. The largest absorbance increase was provided by CTMAB, which was therefore chosen for determination of rare earth elements. REE-XO-CTMAB complex has absorption maxima at 618nm and obeys the Beer's law in the range of 0~0.5 ppm. Molar absorptivity was $1.5{\times}10^5mol^{-1}cm^{-1}l$.