• 한국물환경학회지
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• 제25권4호
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• pp.597-605
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• 2009

Algae bloom occurred in reservoir in summer can cause taste and odor in water and disturb the flocculation and sedimentation processes in water treatment plant and cause sand filter plugging. It was also reported that microcystins, anatoxin and saxitoxin released from cyanobacteria had acute toxic effects on liver and nervous system. For these reasons, many advanced countries inclusive of WHO set the guideline for these toxins and cyanotoxins have been managed with regular monitoring in Korea as well. However, complex sample preparation steps such as a solid phase extraction (SPE) and derivatization are required with an existing analysis method with HPLC. We needed to improve an analysis method for low extraction efficiency and long sample preparation time. In this study, we have established a new LC/MS/MS method which can simultaneously determine 6 cyanotoxins (Microcystins-LR, Microcystins-RR, Microcystins-YR, Anatoxin-a, Saxitoxin, Neosaxitoxin) with only simple filtration step. When $75{\mu}L$ filterated sample was injected onto the LC-MS/MS, the recovery ranged from 86% to 112% and the MDL was $0.025{\sim}0.581{\mu}g/L$. We can make the MDL be lower than the guideline ($1{\sim}3{\mu}g/L$) of advanced countries with simple preparation.

• 한국연초학회지
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• 제23권1호
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• pp.45-52
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• 2001

This study was carried out to evaluate the uncertainty in the analysis of total alkaloids and reducing sugar content in flue-cured tobacco. The sources of uncertainty associated with the analysis of total alkaloids and reducing sugar were the weighing of sample, the preparation of extracting solution, the addition of extracting solution into the sample, the preparation of standard solution, the precision of calibration curve for standard solution, the reproducibility of analysis, and the determination of water content in tobacco, etc. For the calculating uncertainties, Type A of uncertainty was evaluated by the statistical analysis of a series of observation, and Type B by the information based on supplier’s catalogue and/or certificated of calibration. It was shown that the main source of uncertainty was caused by the calibration curve of standard solution, the reproducibility of analysis, the volume measurement of 1$m\ell$, and the purity of nicotine reference material in the preparation of standard solution. The uncertainty in the addition of extracting solution, the sample weighing, the volume measurement of 100$m\ell$, and the determination of water content of tobacco contributed relatively little to the overall uncertainty. The expanded uncertainty of total alkaloids and reducing sugar in flue-cured tobacco at 95% level of confidence was $\pm$0.12% and $\pm$0.54%, respectively.

• Bulletin of the Korean Chemical Society
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• 제33권11호
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• pp.3745-3748
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• 2012

This study presents a rapid and simple ${\alpha}$ source preparation method for a radioactive waste sample. The recovery of $^{239}Pu$, $^{232}U$ and $^{243}Am$ using a micro-coprecipitation method was over 95%. The ${\alpha}$-peak resolution of Pu and Am isotopes through the micro-coprecipitation method is enough to discriminate the Pu and Am isotopes from other Pu and Am isotopes. The determination of the Pu and Am isotopes using the micro-coprecipitation method was applied to the radioactive waste sample, so that the activity concentrations of the Pu and Am isotopes using the micro-coprecipitation method in the radioactive waste sample were similar to those using the electrodeposition method.

• Applied Microscopy
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• 제46권4호
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• pp.188-192
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• 2016

Proper sample preparation prior to microscopy is necessary for maintaining the components of tissues in a state as close to a living state as possible. For optimal preservation of biological samples, the sampling conditions are as important as the fixation itself. Various factors influence the selection and fixation efficiencies of a fixative, including sample size, osmolarity, pH, penetration rate and depth, fixative temperature, fixation time, fixative concentration, fixative amount, and retention time. Therefore, several factors for selecting and administering fixation procedures are evaluated pertaining to optimal sample preparation for transmission electron microscopy.

• 대한금속재료학회지
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• 제48권8호
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• pp.730-740
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• 2010

Aluminum, magnesium, titanium and high Mn steel are difficult to use in electron backscatter diffraction (EBSD) sample preparation due to the formation of an oxidation layer under conventional polishing. Alcohol-based polishing with colloidal silica suspension was introduced for these delicate samples. A hard particle-embedded sample was analyzed successfully using mechanical polishing. Ion-milling was effective in removing oxidized, deformed and transformed layers after mechanical polishing and was able to reduce artifacts significantly. The microstructure of a cross-section of a thin copper film was evaluated by attachment of a dummy to the film for mechanical polishing.

• Applied Microscopy
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• 제51권
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• pp.8.1-8.7
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• 2021

Growing demands for comprehending complicated nano-scale phenomena in atomic resolution has attracted in-situ transmission electron microscopy (TEM) techniques for understanding their dynamics. However, simple to safe TEM sample preparation for in-situ observation has been limited. Here, we suggested the optical microscopy based micro-manipulating system for transferring TEM samples. By adopting our manipulator system, several types of samples from nano-wires to plate-like thin samples were transferred on micro-electro mechanical systems (MEMS) chip in a single step. Furthermore, the control of electrostatic force between the sample and the probe tip is found to be a key role in transferring process.

• 가족자원경영과 정책
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• 제16권2호
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• pp.59-76
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• 2012

This study examines the relationship between intergenerational financial resource transfers and preparation for later life among the middle-aged. The study sample consists of 1536 middle-aged individuals with at least one living parent and one married child. The level of preparation for later life is dependent upon the level of household economic status. The statistically significant variables predicting the level of preparation for later life include age, education, subjective health status, household income and household assets. Moreover, intergenerational resource transfers are statistically significant factors that explain the level of preparation for later life. The effect of financial transfers from middle-aged parents to their adult children on the level of preparation for later life is the most significant financial transfer variable.

• 대한수의학회지
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• 제43권3호
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• pp.393-398
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• 2003

Simple and rapid sample preparation method for trace elements in foods of animal origin using ultra high pressure microwave digestion system (UHP/MDS) and inductively coupled plasma atomic emission spectrometer (ICP/AES) were developed. 1. For the digestion of sample using UHP-MDS, 20% nitric acid (v/v) was the most suitable solvent for the determination of trace elements in foods of animal origin. 2. The optimal digestion conditions for UHP-MDS were as follows: final temperature $180^{\circ}C$, final pressure 400 PSI, and magnetic power 900 W in the solid sample. For the liquid sample final temperature $170^{\circ}C$, final pressure 300 PSI and magnetic power 700 W were optimal conditions. 3. As result of interlaboratory test, the average recovery rate of the for solid sample were 88.3~99.1% for As, 82.4~93.3% for Cd, 89.2~101.2% for Hg and 86.5~93.8% for Pb, respectively. In liquid sample, it were 87.0~96.8% for As, 80.9~96.6% for Cd, 87.5~91.2% for Hg and 91.4~95.5% for Pb, respectively. 4. The average coefficient variation rate were 3.3~15.9% for solid sample and 2.9~10.8% for liquid sample.

• 대한치과기공학회지
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• 제37권3호
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• pp.145-155
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• 2015

Purpose: The Purpose of the study is to investigate the need for the preparation of old age of Korean dental technicians. Methods: A total of 778 dental technicians were selected by proportional stratified by region compared to extraction sampling from a list of Korea dental technician Association in 2012. The final sample size was 386. Questionnaires consisted of 9 general characteristics, recognition of old age 4, and preparation of old age 9 on a Liken 5 scale. Cronbach's alpha was 0.784 in the study. All statistical analyzed were performed using SPSS 14.0(Statistical Packages for Social Science Ver. 14.0. Chicago, IL, USA). Results: Factors affecting the aging preparation is gender, age, clinical career, work place(p<0.001). Conclusion: This study suggested that preparation for old age of Korean dental technicians was very important and the preparation must be connected with the social welfare policy.

• 한국식품영양학회지
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• 제19권4호
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• pp.532-538
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• 2006

Physicochemical and sensory characteristics of the jelly prepared with various levels of resistant starch were investigated in this study. Water content of RS10 sample group had significantly the highest value of 12.55% and that of the RS20 sample group had significantly the lowest value of all (p<0.05). RS20 sample group had significantly the highest value in sweetness. The value of pH were decreased with increased levels of the resistant starch in jelly preparation. The Hunter L values were not significantly different among the sample groups, but the RS20 sample group had the highest value of all. The hardness was increased as the addition levels of the resistant starch was increased. Results of sensory characteristics of RS20 sample group showed significantly the higher values in strawberry aroma, sweetness and after taste and significantly the lower value in stickiness than those in the other sample groups at p<0.05. Strawberry flavor, springiness and glossiness of RS5 sample group had significantly the largest values of all (p<0.05). The sensory properties of clarity and glossiness were negatively correlated with the mechanical properties of the color value and hardness at p<0.05. Sensory sweetness and after taste showed negative correlation with the values of pH in jelly preparation(p<0.05).