• Korean Chemical Engineering Research
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• v.56 no.6
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• pp.832-840
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• 2018

In this study, both of the concentration of benzo(a)pyrene in 5 species (total 50 samples) of medicinal herbs and their transfer ratios in the preparation steps of water extract(decoction) and soft extract, were measured by HPLC/FLD. The calibration curve of benzo(a)pyrene shows excellent correlation over the concentration range of 3~40 ng/mL with the correlation coefficient ($R^2$) of 1.000. The detected benzo(a)pyrene concentrations from the medicinal herbs ranged from non-detection to $37.54{\mu}g/kg$, and their average was $6.73{\mu}g/kg$. Among the total samples, 15 samples (i.e., 30%) exceeded the limit of herbal medicine benzo(a)pyrene criteria (i.e., $5{\mu}g/kg$) according to the notification No. 2009-302 from Ministry of Food and Drug Safety. In particular, the concentration of benzo(a)pyrene in Coptidis Rhizome was turned out to be the highest of $37.54{\mu}g/kg$. The detected benzo(a)pyrene concentrations from water extract(decoction), soft extract and remnant after boiling, ranged from non-detection to $2.31{\mu}g/kg$, non-detection to $2.28{\mu}g/kg$, and 2.18 to $21.91{\mu}g/kg$, respectively. In preparation of water extract(decoction) and soft extract, transferred benzo(a)pyrene was not detected or, if transferred, the maximal transfer ratios of benzo(a)pyrene were shown to be 8.9% and 9.8%, respectively. Therefore, the content of benzo(a)pyrene in the samples of herbal medicine used in this study, were reduced by more than 90% in preparation steps of water extract (decoction) and soft extract.

• Journal of The Korean Association For Science Education
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• v.43 no.2
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• pp.125-137
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• 2023

This study analyzed the types of knowledge building discourse and knowledge building processes in small group learning using augmented reality. Eight 8th grade students took classes using augmented reality in solubility, boiling and melting points. These classes were carried out twice and all the classes were videotaped and recorded. Every student participated in a semi-structured interview. In the types of knowledge building discourse, the proportion of knowledge sharing and knowledge construction was similar. Beneath the knowledge sharing, the proportion of introductory level discussion was higher than identifying key elements of augmented reality. Recalling existing knowledge rarely appeared. Under the knowledge construction, the proportion of advanced level discussion was the highest and the proportion of sharing and critiquing ideas at a different level and efforts to rise above current levels of explanation was similar. The introductory level discussion and identifying key elements of augmented reality were developed into efforts to rise above current levels of explanation and sharing and critiquing ideas at a different level. Visualized results of knowledge building processes showed all the students' graph drew an upward curve, though cumulative number of impact value was different by each student. As a result of the study, effective ways of improving small group learning using augmented reality are discussed.