• 한국수학교육학회지시리즈A:수학교육
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• 제60권4호
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• pp.409-429
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• 2021

본 연구는 초등학교 6학년 학생들을 대상으로 대수적 사고를 강조하여 분수 나눗셈을 지도하는 방안을 분석한 것이다. 문헌 연구에서 도출한 교수·학습 요소를 중심으로 분수 나눗셈 수업을 재구성하고, 실제 수업에서 주요 교수·학습요소가 어떻게 구현되는지 그 양상을 분석하였다. 특히 본 논문에서는 나누는 수 1에 대응하는 나누어지는 수의 양을 구하는 문제 맥락을 중심으로 분석하였다. 이를 토대로 초등학교 분수 나눗셈 수업에서 대수적 사고를 강조하여 지도하는 방안에 관한 구체적인 시사점을 도출하였다.

• 유기물자원화
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• 제22권3호
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• pp.41-52
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• 2014

본 연구에서는 부정기적 발생 오수의 생분해도 특성 parameters를 현장 시료채취 및 분석실험을 실시하여 조사 및 분석하였으며 결과는 다음과 같다. TCODcr (Total CODcr)의 1,2차 평균 농도는 325.5 mg/L 이며 TCOD 분율은 100% 로 분석되었다. SCODcr (Soluble CODcr)의 1,2차 평균 농도 는 135.9 mg/L 이며 TCOD 분율은 41.8% 로 분석되었다. Ss (Readily biodegradable substrate)의 1,2차 평균 농도는 74.1 mg/L 이며 TCOD 분율은 22.8% 이다. $S_I$ (Soluble inert non-biodegradable substrate)의 1,2차 평균 농도는 61.8 mg/L 이며 TCOD 분율은 19.0% 이다. Xs(Slowly Biodegradable Substrate)의 1,2차 평균 농도는 27.8 mg/L 이며 TCOD 분율은 8.5% 이다. $X_H$의 1,2차 평균 농도는 103.4 mg/L 이며 TCOD 분율은 31.8% 이다. $X_I$ (Particulate inert non-biodegradable substrate)의 1,2차 평균 농도는 58.5 mg/L 이며 TCOD 분율은 18.0% 이다. 따라서 대상 시료의 용존성 생분해 가능 유기물질은 41.8%로 분석되었으며, 이중 생분해가 용이한 분율은 22.8%로 나타났다. 이와 같이 부정기적인 유입 유량으로 인한 유량조정 또는 균등조의 운전으로 유입부하 변동폭에 대한 영향은 크지 않을 것으로 판단된다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2005년도 INTERNATIONAL SYMPOSIUM ON SOIL & GROUNDWATER ENVIRONMENT
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• pp.45-46
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• 2005

• Journal of Ecology and Environment
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• 제34권3호
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• pp.315-322
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• 2011

We investigated the effect of Pb uptake by Pinus densiflora and the Pb fraction in forest soil. We also investigated the change in soil physicochemical characteristics, microbial activity, and root exudates of Pinus densiflora in Pb-contaminated soils. Three-year-old pine seedlings were exposed to 500 mg/kg Pb for 12 months. The metal fractions were measured using sequential extraction procedures. Additionally, factors that affect solubility (three soil enzyme activities and amino acids of root exudate compounds) were also determined. The results showed that Pb contamination significantly decreased enzyme activities due to soil characteristics. In addition, organic matter, nitrate content, and Pb concentration were time dependent. The results indicate that changes in the Pb fraction affected Pb uptake by pine trees due to an increase in the exchangeable Pb fraction. The concentrations of organic acids were higher in Pb-spiked soil than those in control soil. Higher rhizosphere concentrations of oxalic acid resulted in increased Pb uptake from the soil. These results suggest that pine trees can change soil properties using root exudates due to differences in the metal fraction.

• 생약학회지
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• 제45권2호
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• pp.141-146
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• 2014

In this study, we investigated on antioxidative activities and tyrosinase inhibitory activities of methanol extract and its fractions from roots of Arctium lappa. The total phenolic compound and flavonoid content of the ethylacetate fraction was found to be 818.29 mg/g and 360.59 mg/g as the highest content. In the measurement of DPPH radical scavenging ability and tyrosinase inhibitory activity, the ethylacetate fraction was higher than the other fractions and the extract. In addition, comparative analysis of phenolic compounds by liquid chromatography-mass spectrometry (MS)/MS system under the multiple-reaction monitoring (MRM) with negative-ion electrospray ionization mode. The main phenolic compounds in the extract and fractions of roots from Arctium lappa were cynarin and chlorogenic acid. The main phenolic compound of the ethylacetate fraction was cynarin. n-Butanol fraction had a significantly higher chlorogenic acid content than other samples. In conclusion, DPPH radical scavenging ability and tyrosinase inhibitory activity of the cynarin-riched ethylacetate fraction showed the highest activity.

• 동의생리병리학회지
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• 제19권1호
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• pp.179-183
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• 2005

Recent interest in the possible protective effects of dietary antioxidant compounds against human degenerative disease has prompted investigation of foods such as blueberries, which have a high antioxidant capacity. This study was performed to determine the antioxidative activity of methanol extract and solvent fractions from blueberry. Blueberry was extracted with methanol and then fractionated with n-hexane, EtOAc, BuOH and water to get active fractions. And their antioxidant capacities in each fraction were determined by using the DPPH and FRAP assay, and tyrosinase inhibitor. Ethyl acetate fraction of blueberry exhibited antioxidant capacity.

• 한국재료학회지
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• 제13권11호
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• pp.756-760
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• 2003

Two dimensional computer simulations were conducted on percolative structure in which second phases with various short diameter were arranged in matrix phase. In case of prohibiting the overlap among the second phases, the maximum area fraction of second phase arranged in matrix was increased with higher short diameter. In case of allowing the overlap among the second phases, the critical area fraction was increased with higher short diameter and the total number of distributed second phase was decreased. This results represented that thickness variation of short diameter by grain growth on the production processes affect significantly forming the completion path.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.1
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• pp.272.1-272.1
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• 2003

Cornis fructus were extracted by successive extraction and then fractionated with hexane extract to get active fractions. This study was performed to determine the cytotoxic effect of hexane extract from Cornis fructus on NIH 3T3 fibroblasts and cancer cell lines using MTT assay. Hexane extract showed cytotoxic effect against A549, B16 melanoma and MDA-MB-231. Further fractionation with hexane extract were performed to obtain effective fraction, fraction 3 showed the cytotoxic effect against A549 and MDA-MB-231 cell line.

• 한국자기학회지
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• 제22권6호
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• pp.216-220
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• 2012

이 연구에서는 근역장 통신(NFC)용 소재로 응용하기 위해, MnZn 페라이트와 FeSi 합금 분말을 filler로 사용하여 제조한 0-3형 자성복합소재의 복소투자율 변화(1 MHz~1 GHz)를 측정하였으며, RFID 주파수(13.56 MHz)에서의 복소투자율 값을 검토한 결과, filler 함량에 따라 투자율 실수항은 증가하고 허수항은 감소하는 결과를 얻었다. 즉, 시트형 자성복합소재의 응용을 위한 연구 결과로서, 고투자율을 나타내면서 손실항인 허수항을 상대적으로 낮출 수 있는 소재 제조공정 기술을 확보할 수 있었으며, 복소투자율 변화는 자성분말 filler의 성분과 입자 형태, 그리고 polymer 종류에 의존함을 알 수 있었다.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 1999년도 학술발표회 진행표 및 논문초록
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• pp.45-45
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• 1999

Cytochrome c (cyt c) binds to acidic membranes at low ionic strength. Replacement of Lys-72 or Lys-87 by Glu reduced the binding affinity of cyt c toward large unilamellar vesicles (LUV) in liquid crystalline phase. The differences were smaller for LUV in gel phase. A fraction of bound cyt c was non-electrostatically associated.(omitted)