• Journal of The Korean Association For Science Education
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• v.34 no.5
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• pp.499-510
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• 2014

The purpose of this research is to understand interactive learning during docent-led tours in a science museum focusing on scaffolding. We developed a scaffolding framework by collating the work of other researchers in related fields. The results show that scaffolding included three dimensions: purpose, interaction, and domain. The purpose dimension, divided into six categories, is related to the intention of the scaffolder and what the scaffolding are for: strategic, social, procedural, conceptual, verbal, and metacognitive. The interaction dimension reflects students' interaction with the scaffolder in two ways: dynamic (situation specific) and static (planned in advance). The domain dimension is related to two contents: domain-general and domain-specific (such as science). The scaffolding framework was applied to dynamic interactions between docents and visitors. The data was collected from elementary school students' family visits with the guidance of two docents at the Seodaemun Museum of Natural History. The data collected consisted of surveys, interviews, video-recordings, and transcripts. The analysis shows that five guiding contexts and scaffolding phases were recognized; 1) strategic scaffolding in a poorly illustrated exhibit; 2) conceptual scaffolding in a thoroughly explanative exhibit; 3) verbal scaffolding in misleading interpretation; 4) procedural scaffolding in a manipulative exhibit; and 5) metacognitive scaffolding with inaccurate content. In addition, the results show that the docents used the dynamic and static scaffolding synthetically so that the docent-led tour was effective. In conclusion, this study presents the usefulness of understanding visitors' science learning through the scaffolding framework, as well as the how docents can scaffold actively.

• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.388-394
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• 2014

BACKGROUND: Aclonifen is used as a systemic and selective herbicide to control a wide spectrum broad-leaf weeds by inhibition carotenoid biosynthesis, and then its MRLs(Maximum Residue Limits) will be determined in onion and garlic. In this study, a new official method was developed for aclonifen determination in agricultural products to routinely inspect the violation of MRL as well as to evaluate the terminal residue level. METHODS AND RESULTS: Aclonifen was extracted from crop samples with acetone and the extract was partitioned with dichloromethane and then purified by silica solid phase extraction(SPE) cartridge. The purified samples were detected GC using an ECD detector. Limits of detection(LOD) was 0.001 mg/kg and quantification(LOQ) was 0.005 mg/kg, respectively. For validation purposes, recovery studies were carried out at three different concentration levels (LOQ, $10{\times}LOQ$, $50{\times}LOQ$, n=5). The recoveries were ranged from 74.3 to 95.0% with relative standard deviations(RSDs) of less than 8%. All values were consistent with the criteria ranges requested in the Codex guidelines(CAC/GL 40). CONCLUSION: The proposed analytical method was accurate, effective and sensitive for aclonifen determination and it will be used to as an official method in Korea.

• Journal of Food Hygiene and Safety
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• v.28 no.3
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• pp.247-251
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• 2013

The objective of present study was to develop a simultaneous determination method of 5 medical compounds, including beclomethasone, dexamethasone, prednisolone, ketoprofen, phenylbutazone in foods, using LC-MS/MS. To optimize MS analytical condition of 5 compounds, each parameter was established by MRM mode. The chromatographic separation was achieved on a C18 column successfully, with a mobile phase made up of A (0.1% formic acid) and B (0.1% formic acid in acetonitrile), at a flow rate of 0.3 mL/min for 17 min with a gradient elution. LOD and LOQ of 5 compounds were in the range of 0.40~4.60 ng/mL and 0.81~11.46 ng/mL, respectively. As a result of analyzing the three concentrations of the standard mixture added to blank samples, the results showed that the mean recovery rate of 5 compounds was in the range of 81.52~103.83%, and RSD (%) of Intra- and Inter-day assay were 0.52-10.45. Since relatively fine selectivity, accuracy and reproducibility were shown in this qualified experimental method, it could be utilized efficiently to investigating those 5 compounds to see if it is added to food products illegally.

• Journal of Food Hygiene and Safety
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• v.26 no.1
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• pp.16-24
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• 2011

A method was established for the simultaneous determination of sugar alcohols, erythritol, xylitol, sorbitol, inositol, mannitol, maltitiol, lactitol and isomalt by High Performance Liquid Chromatography (HPLC). The sugar alcohols were converted into strong ultraviolet (UV)-absorbing derivatives with p-nitrobenzoyl chloride (PNBC). HPLC was performed on Imtakt Unison US-$C_18$ column, using acetonitrile: water (77:23) as a mobile phase and UV detection (260 nm). The calibration curves for all sugar alcohols tested were linear in the 10~200 mg/L range. The average recoveries of the sugar alcohols from three confectioneries spiked at 100 ppm of eight sugar alcohol standards ranged from 81.2 to 123.1% with relative standard deviations ranging fromo 0.2 to 4.9%. The limits of detection (LODs) were $0.5{\sim}8\;{\mu}g/L$ and the limits of quantification (LOQs) were $2{\sim}17\;{\mu}g/L$. Reproducibility of 8 sugar alcohols was 0.28~1.97 %RSD. The results of the analysis of confectioneries showed that 89 samples of 130 were detected and the sugar alcohols content of samples investigated varied between 0.4 and 693.7 g/kg. A method for the simultaneous determination of eight sugar alcohols will be used as basic data for control of sugar alcohols in confectioneries, and quality control in food manufacturing.

• Korean Journal of Environmental Agriculture
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• v.14 no.2
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• pp.186-201
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• 1995

In order to elucidate the fate of the residues of the pyrethroid acaricide-insecticide, acrinathrin in soil, maize plants were grown for one month on the specially-made pots filled with two different types of soils containing fresh and one-month-aged residues of [$^{14}C$]acrinathrin, respectively. The mineralization of [$^{14}C$]acrinathrin to $^{14}CO_2$ during the one-month period of aging and of maize cultivation amounted to $23{\sim}24%$ and $24{\sim}33%$, respectively, of the original $^{14}C$ activities. At harvest after one-month growing, the shoots and roots contained less than 0.1% and 1% of the originally applied $^{14}C$ activity, respectively, whereas the $^{14}C$ activity remaining in soil was $65{\sim}80%$ in both soils. Three degradation products with m/z 198(3-phenoxybenzaldehyde), m/z 214(3-phenoxybenzoic acid), and m/z 228(methyl 3-phenoxybenzoate) besides an unknown were identified from acetone extracts of both soils without and with maize plants after treatment of [$^{14}C$]acrinathrin, by autoradiography and GC-MS, and those with m/z 225(3-phenoxybenzaldehyde cyanohydrin) and m/z 198 (3-phenoxybenzaldehyde) from acetone extract of the Soil A treated with 50 ppm acrinathrin and grown with maize plants for 30 days were identified by mass spectrometry. These results suggested that the hydrolytic cleavage of the ester linkage adjacent to the $^{14}C$ with a cyano group, forming 3-phenoxybenzaldehyde cyanohydrin. The removal of hydrogen cyanide therefrom leads to the formation of 3-phenoxybenzaldehyde as one of the major products. The subsequent oxidation of the aldehyde to 3-phenoxybenzoic acid, followed by decarboxylation would evolve $^{14}CO_2$. Solvent extractability of the soils where maize plants were grown for 1 month and/or [$^{14}C$]acrinathrin was aged for 1 month was less than 31% of the original $^{14}C$ activity and over 95% of the total $^{14}C$ activity in soil extracts was distributed in the organic phase. Accordingly, acrinathrin turned out to be degraded rapidly in both soils and be bound to soil constituents as well, not being available to crops.

• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.3
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• pp.159-164
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• 2009

Purpose: The automatic notification system for alarm values on blood tests conducted by this hospital is designed to immediately inform the attending physician of the result of a blood test, to help the relevant patient to promptly receive proper treatment, and furthermore, to reduce the likelihood of a fatal influence to the patient. From 2004, the clinical pathology department of this hospital has been operating an automatic notification system for blood tests, in relation to the items of WBC, Hb, Plt, PB cell morphology, Malaria, PT, aPTT, BT, fibrinogen, Ca, K, Na, Cl, Mg, Glucose, Ketone, Digoxin, PKU, Homocystinuria, 17-OHP, Neonatal TSH, and Galactosemia. Recently, the blood test room of the nuclear medicine department has been operating an automatic notification system for the alarm values of a blood test, in relation to three items of TSH, FT4, and 17-${\alpha}$-OH-PGR, and the details of its operation will be described here. Materials and Methods: The subjects were newborn babies that were receiving TSH, FT4, and $17{\alpha}$-OH-PGR prescriptions from February $19^{th}$ to May $11^{st}$, 2009, and who met with the following criteria: N2340 Thyroid-Stimulating Hormone: >$10{\mu}IU/mL$ (Reference value: 0.4~5.0). N2360 Free-Thyroxine: <$0.8{\mu}g/dL$ (Reference value: 0.8~1.9), N2444 $17{\alpha}$-OH-Progesterone: >$30\;{\mu}g/mL$ (Reference value: Male (0.6~3.42), Female follicular phase (0.19~1.8). The automatic notification system was operated by entering test items, relevant treatment departments, and standard values for reporting alarm values into the OCS program, and then transmitting results that met with the input conditions to the PDAs of the prescription and the attending physician by SMS. Results: Reporting an alarm value of the nuclear medicine blood test, which can have a fatal influence on the lives of patients, will help cure patients, improve the quality of the test, and furthermore, will increase the patient's satisfaction with the prescription and treatment of the test.

• Investigative Magnetic Resonance Imaging
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• v.8 no.1
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• pp.42-49
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• 2004

Purpose : The quantization noise in magnetic resonance imaging (MRI) systems is analyzed. The signal-to-quantization noise ratio (SQNR) in the reconstructed image is derived from the level of quantization in the signal in spatial frequency domain. Based on the derived formula, the SQNRs in various main magnetic fields with different receiver systems are evaluated. From the evaluation, the quantization noise could be a major noise source determining overall system signal-to-noise ratio (SNR) in high field MRI system. A few methods to reduce the quantization noise are suggested. Materials and methods : In Fourier imaging methods, spin density distribution is encoded by phase and frequency encoding gradients in such a way that it becomes a distribution in the spatial frequency domain. Thus the quantization noise in the spatial frequency domain is expressed in terms of the SQNR in the reconstructed image. The validity of the derived formula is confirmed by experiments and computer simulation. Results : Using the derived formula, the SQNRs in various main magnetic fields with various receiver systems are evaluated. Since the quantization noise is proportional to the signal amplitude, yet it cannot be reduced by simple signal averaging, it could be a serious problem in high field imaging. In many receiver systems employing analog-to-digital converters (ADC) of 16 bits/sample, the quantization noise could be a major noise source limiting overall system SNR, especially in a high field imaging. Conclusion : The field strength of MRI system keeps going higher for functional imaging and spectroscopy. In high field MRI system, signal amplitude becomes larger with more susceptibility effect and wider spectral separation. Since the quantization noise is proportional to the signal amplitude, if the conversion bits of the ADCs in the receiver system are not large enough, the increase of signal amplitude may not be fully utilized for the SNR enhancement due to the increase of the quantization noise. Evaluation of the SQNR for various systems using the formula shows that the quantization noise could be a major noise source limiting overall system SNR, especially in three dimensional imaging in a high field imaging. Oversampling and off-center sampling would be an alternative solution to reduce the quantization noise without replacement of the receiver system.

• Journal of Animal Science and Technology
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• v.48 no.6
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• pp.871-880
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• 2006

This study was conducted to estimate the maximum amount and time of milk consumption by Holstein calves during two months of pre- weaning period and to compare ad libitum milk feeding with conventional system for their effects on dry feed consumption, nutrient intake, growth performance and occurrence of diarrhea during the pre-weaning phase. Holstein calves (n=20) were alternatively fed colostrum at 10% of their body weight or ad libitum for the first three days (d) and then assigned either to conventional (n=10; calves were fed milk at 10% of their body weight from birth to weaning at d 60 of their age) or ad libitum milk feeding (n=10; calves were fed ad libitum milk from birth to weaning at d 60 of their age). Milk intake as a percent of body weight was increased in ad libitum fed calves from 13.59% at d 1 to 23.50% at d 30 of their age, thereafter it was gradually reduced. Ad libitum fed calves consumed daily 9.8kg milk compared with 4.3kg milk in restricted fed calves(p<0.05). Daily starter and mixed grass hay intake was gradually increased in both groups with the age however; the group differences were noted non-significant up to 40 d of age. Overall from birth to weaning conventionally fed calves ate 18.4, 20 and 18.9% more dry matter, crude protein and total digestible nutrients, respectively than ad libitum milk fed calves (p<0.05). Weight gain was 49, 18.4 and 26% higher in ad libitum milk fed calves than conventionally fed calves during the first month, the second month and from birth to weaning, respectively(p<0.05). Body weight was not significantly different between groups for the first 20 d of age. However, it was significantly higher for ad libitum milk fed calves at d 30, 40, 50, 60 (weaning) and 90 (post weaning) of their age(p<0.05). Similar body weights for both conventionally and ad libitum milk fed calves were observed for the post weaning period at 120, 150 and 180 d of age. Feed efficiency was significantly higher for conventionally fed calves than ad libitum milk fed calves(p<0.05). No sign of diarrhea, fever or cough was observed in calves fed either conventionally or ad libitum milk during the experimental period. In conclusion, calves fed more milk remained healthy and gained higher weight before weaning and maintained this advantage at least up to 90 d of their age.

• Korean Journal of Environmental Agriculture
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• v.25 no.4
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• pp.306-315
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• 2006

Two different experiments, adsorption/desorption and runoff by rainfall simulation of four pesticides, such as alachlor, ethalfluralin, ethoprophos and pendimethalin were undertaken their runoff and erosion losses from sloped land and to assess the influence of their properties and environmental factors on them. The mobility of four pesticides and which phase they were transported by were examined in adsorption study, and the influence of rainfall pattern and sloping degree on the pesticide losses were evaluated in simulated rainfall study. Freundlich adsorption parameters (K) by the adsorption and desorption methods were 1.2 and 2.2 for ethoprophos, 1.5 and 2.6 for alachlor, respectively. And adsorption distribution coefficients (Kd) by the adsorption and desorption methods were 56 and 94 for ethalfluralin, and 104 and 189 for pendimethalin, respectively. K or Kd values of pesticides by the desorption method which were desorbed from the soil after thoroughly mixing, were higher than these ones by the adsorption method which pesticides dissolved in water were adsorbed to the soil. Another parameter (1/n), representing the linearity of adsorption, in Freundlich equation for the pesticides tested ranged from 0.96 to 1.02 by the desorption method and from 0.87 to 1.02 by the adsorption method. Therefore, the desorption method was more independent from pesticide concentration in soil solution than the adsorption method. By Soil Survey and Land Research Center (SSLRC)'s classification for pesticide mobility, alachlor and ethoprophos were classified into moderately mobile $(75{\leq}Koc<500)$, and ethalfluralin and pendimethalin were included to non-mobile class (Koc > 4000). Runoff and erosion loss of pesticides by three rainfall scenarios were from 1.0 to 6.4% and from 0.3 to 1.2% for alachlor, from 1.0 to 2.5% and from 1.7 to 10.1% for ethalfluralin, from 1.3 to 2.9% and from 3.9 to 10.8% for pendimethalin, and from 0.6 to 2.7% and from 0.1 % 0.3% for ethoprophos, respectively. Distribution of pesticides in soil profile were investigated after the simulated rainfall study. Alachlor and ethoprophos were leached to from 10 to 15 cm of soil layer, but ethalfluralin and pendimethalin were mostly remained at the top 5 cm of soil profile. The losses of the pesticides at 30% of sloping degree were from 0.2 to 1.9 times higher than those at 10%. The difference of their runoff loss was related with their concentration in runoff water while the difference of their erosion loss must be closely related with the quantity of soil eroded.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.420-430
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• 2005

This study was performed to change the hydrophilic $NH_4Y$-zeolite to the hydrophobic one for removal of VOCs by removing the $Al^{3+}$ in the zeolite-structure to increase the Si/Al ratio, for which the three pelleted $NH_4Y$-zeolite samples were contacted separately with the steam of $400^{\circ}C$, $500^{\circ}C$ and $600^{\circ}C$, respectively, in a stainless steel column for 4 hours. Then extraction of the ex-structure aluminum of the hydrolyzed zeolites with the nitric acids of 0.25, 0.50, 0.75, and 0.10 M at $90^{\circ}C$ in 500 mL-flasks, respectively, according to steam temperature were followed. XRD analysises of the dealuminated zeolites showed that the peaks of the zeolites that had been hydrolyzed with the steams of both $500^{\circ}C$ and $600^{\circ}C$ are distorted more with the increase of the concentration of nitric acid used for extraction of the ex-structure aluminums, however, those hydrolyzed with steam of $400^{\circ}C$ became amorphous phase when treated with the all nitric acids of four concentrations. Also the EDX analysises showed that the BET surface areas and TPVS of the zeolites that had been hydrolyzed with the steam of $600^{\circ}C$ were increased with the concentration of the nitric acid when the nitric acids of 0.25 M and 0.5 M had been used but decreased when the nitric acids of 0.75 M and 1.0 M had been used. These results led to the conclusion that both the $600^{\circ}C$ and $500^{\circ}C$-steam and the 0.5 M-nitric acid are appropriate to change the hydrophilic $NH_4Y$-zeolites to the hydrophobic one, which were proven by the measurement of the benzene and tolune-adsorbing capacities showing the same trend as the BET surface area and TPV The Si/Al ratios and water-adsorbing capacities of the dealuminated zeolites were increased and decreased, respectively, with the concentration of the nitric acids so that it showed that the hydrophobicity is increased.