• The Journal of the Petrological Society of Korea
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• v.14 no.4 s.42
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• pp.237-250
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• 2005

In order to clarify the effect of standard rock material in the chemical analysis of rare earth element abundance with ICP-MS, we measured rare earth element abundance of KIGAM granite standard rock material (KG-1), USGS granite standard rock material (G-2), GSJ granite standard rock materials (JG-1a and JG-2). In REE analysis, we used conventional calibration standard solutions, KG-1, JG-1a, JG-2 and G-2 as standard material, respectively. Chondrite-normalized LREE patterns of low granite standard material correspond well each other in the recommended value and the estimated value regardless of a kind of standard rock. However, the HREE patterns of the estimated value based on G-2 or JG-2 and the recommended value are different from each other. Such difference may be due to the wrong recommended value or a specific geochemical properly of the standard rock material itself, The chondrite-normalized REE patterns of four standard rock materials estimated on the basis of KG-1 or JG-1 a show little deviation compared to the those of the recommended values. This suggests that KG-1 and JG-1a may be a optimum standard material for granitoids.

• Korean Journal of Food Science and Technology
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• v.22 no.2
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• pp.183-191
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• 1990

Soy milk prepared from soy protein concentrate was added with each of four types of milk products. Acid production and growth of five species of lactic acid bacteria(LAB) in soy milk and sensory property of soy yogurt were investigated. Acid production by LAB increased in proportion to concentration of milk products added to soy milk. Among the four milk products tested, whey powder or skim milk powder stimulated acid production by LAB more than whole milk powder or modified milk powder. Stimulating effect by whey powder on acid production by LAB was greater than other milk products at low concentration. Acid production by LAB in soy milk added with glucose or milk products significantly increased during fermentation. Sensory property of soy yogurt added with whole milk powder or skim milk powder was better than that of reference (soy yogurt added with glucose) while sensory property of soy yogurt added with whey powder or modified milk powder was Inferior to that of reference.

• Korean Journal of Food Science and Technology
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• v.36 no.1
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• pp.123-128
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• 2004

Effects of jeotkal (salted-fermented seafoods) addition on acid production, growth of lactic acid bacteria, sensory properties, and volatile odor components of kimchi were investigated. Changes in pH and acidity of kimchi added with myulchi-aekjeot, kanari-aekjeot, and aekche-Jukjeot were similar to, whereas those of saeu-jeot sample on 0, 2, and 4 days of ripening were slightly different, those of control sample. Changes in pH and acidity of jogae-jeot sample during whole ripening period were markedly different from those of other samples. Numbers of lactic acid bacteria of all samples on 0 and 4 days were $1.8-2.6{\times}10^{5}\;and\;1.0-2.5{\times}10^{9}\;CFU/mL$, respectively. Overall acceptability and taste of kimchi added with jeotkal except jogae-jeot were higher than those of control sample, with saeu-jeot-added kimchi showing the highest scores. Eight volatile odor components were identified in 6-day-ripened kimchi samples, and those of saeu-jeot sample were slightly higher than those of other samples. Diallyl sulfide and methyl propyl disulfide were produced in 6-day-ripened samples. Ethanol, methyl allyl sulfide, and dimethyl disulfide concentrations increased, whereas that of allyl mercaptan decreased in 6-day-ripened samples compared to unripened ones.

• Korean Journal of Food Science and Technology
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• v.33 no.1
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• pp.100-106
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• 2001

The objective of this study was to improve the shelf-life of kimchi by freeze drying. Kimchi was freeze dried and stored at $0^{\circ}C$, $5^{\circ}C$ and $28^{\circ}C$ for 60 days. It was reconstituted with water at an interval of ten days and number of total lactic acid bacteria(LAB), sensory properties and shape/color were observed. The results were as follows: (1) Number of total LAB of sample stored at $0^{\circ}C$ or $5^{\circ}C$ for 60 days decreased gradually and the value of 10 day-sample and 30 day-sample was significantly different from the value of 0 day-sample and 20 day-sample, respectively (p<0.05). Number of total LAB of sample stored at $28^{\circ}C$ decreased more rapidly in comparison with that of sample stored at $0^{\circ}C\;or\;5^{\circ}C$. (2) Overall acceptability, taste, moistness and chewiness of freeze dried/reconstituted kimchi slightly decreased by freeze drying. However, acceptability of freeze dried/reconstituted kimchi was relatively good. (3) Overall acceptability of freeze dried/10 days-stored/reconstituted sample was slightly lower than that of reference sample (not-freeze dried sample). Overall acceptability of sample stored at $28^{\circ}C$ for 50 days decreased substantially in comparison with sample stored at $28^{\circ}C$ for 10 day. (4) In case of freeze dried/stored samples, sensory properties of sample stored at $5^{\circ}C$ for 60 days were not different from those of reference(sample stored at $0^{\circ}C$). Overall acceptability, taste, texture and crispness of sample stored at $28^{\circ}C$ started to decrease after 10 days. Odor and color of sample stored at $28^{\circ}C$ were changed after 50 days and 60 days, respectively.

• Korean Journal of Food Science and Technology
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• v.16 no.2
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• pp.159-164
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• 1984

The effects of some hydrocolloids such as carboxymethylcellulose, xanthan gum, gum arabic, and sodium alginate, on quality attributes of rice cake (packsulki) were investigated. Fresh(F) and refrigerated(R) packsulkis were evaluated by sensory evaluation and with Instron Testing Mashine. The results of sensory evaluation indicated the differences among packsulkis with and without additive. Hardness of packsulkis increased markedly when refrigerated. Differences among R groups were much smaller compared to those among F groups. Textural characteristics measured by Instron also revealed the differences among the groups. They showed similar tendancy to those of sensory evaluation.

• Journal of the Korean Magnetics Society
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• v.18 no.1
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• pp.1-8
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• 2008

We have manufactured and evaluated reference samples for the use of low magnetic moment measurements. Before the measurements, SQUID magnetometers were magnetically shielded from external magnetic noise. We considered the purity including magnetic impurities, the optimum thickness, the modification method, and the shape in the preparation of the samples. Three paramagnetic polycrystaline metal plates of Ti, W, and Al with the area of $4mm{\times}6mm$ were prepared finally. The magnetic moments of these three samples are measured very linear up to the field of 5 T without magnetic hysteresis. The temperature deviated ratios of the magnetic moments for Ti, Al, and W from 290 K to 310 K are 0.7, 1.5, and 0.1 %, respectively. The measured magnetic moments for Ti and W samples by our research team are very well agreeable with those by two SQUID magnetometers and a VSM at Quantum Design via international round robin test. The results suggest that the prepared reference samples are well suited for the use in the low magnetic moment measurement with SQUID based magnetometers.

• Analytical Science and Technology
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• v.10 no.5
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• pp.386-394
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• 1997

The standard samples for the calibration of PIXE analysis were prepared using the single element standard samples and sulfur and chlorine compounds. The diluted standard solutions were dropped on the non-hole nuclepore film and dried. Standard sample of six elements of Ca, Cr, Co, Cu, Se and Sr had close agreement between the measurement and theoretical values. According to the theoretical study about the effects of thick samples on the accuracy of the PIXE analysis, the reduction of X-ray yields in the thick sample can not be neglected for the sample thicker than $100{\mu}g/cm^2$.

• Analytical Science and Technology
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• v.29 no.6
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• pp.261-268
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• 2016

TXRF is a powerful technique for the soil sample analysis due to its ability to conduct quantitative analysis of powder sample without complicated pre-treatment processes. The conventional internal standard method used for this technique suffers from relatively low accuracy because of varying matrix effects of soil. In order to improve the accuracy, external standard method was applied to analyze two types of soil samples; acid-dissolutionized soil solution and detergent-suspended soil powder. Individual ICP-AES/MS grade standards were mixed, diluted and measured to create standard curves, but applying these curves for analyzing the soil solution sample did not make any improvement in comparison with the internal standard method. On the other hand, standard curves were created with using standard soil powders for the analysis of soil powder samples, and we found that this method increased the accuracy significantly relative to the internal standard method. Especially, Al, Fe, K, Ca, Ti, Ba, Mn, Sr, Rb, Cu was measured with relatively high accuracy (relative error = ${\pm}20%$).

• Analytical Science and Technology
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• v.22 no.5
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• pp.369-375
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• 2009

We evaluated the homogeneity and accuracy of low level airborne fibrous standard, and accomplished the proper proficiency test. We had found that the correlation of concentration of standard solution and asbestos density was 0.9863~0.9968, and concluded that the proper guideline of the analysis result was ${\mid}Z{\mid}{\leq}2$ interval of Z-score.

• Analytical Science and Technology
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• v.27 no.6
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• pp.339-346
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• 2014

The author assessed the availability of urine reference material for proficiency test provided for laboratories in occupational health. N-methylacetamide is the biomarker of exposure to N,N-dimethyl acetamide, which was used as the substitute for hepatotoxic N,N-dimethylformamide (DMF). N-methylacetamide (NMAC) urine samples of 3 different levels covering the 0.2~2 times of the exposure limit were tested. Stability test up to 180 days (0, 7, 30, 60, 180 days) at 4 different temperatures (-60, -20, 5, $25^{\circ}C$) and homogeneity test were performed for these samples. New analytical condition by GC/MSD using SIM mode (m/z 58, 59) and DB-624 column was investigated for better selectivity, sensitivity and resolution. Urinary NMAC samples showed good homogeneity for 3 levels. These samples also showed good stability up to 180 days. The data of stability and homogeneity of urinary DMAC confirmed the basis of including this item into Korean proficiency test for occupational health laboratories since 2008.