• 대한수학교육학회지:수학교육학연구
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• 제27권3호
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• pp.351-373
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• 2017

나눗셈의 의미는 수의 범위가 확장되어도 연결된다. 즉, 자연수 범위에 적용되는 나눗셈의 의미는 분수 및 소수를 다루는 유리수 범위로 확장되어도 적용가능하다. 이러한 측면에서 자연수의 나눗셈과 분수의 나눗셈, 소수의 나눗셈을 서로 연결하여 가르치는 것은 수학의 내적 연결성을 통하여 나눗셈을 의미 있게 학습하는데 도움이 될 것이다. 본 연구에서는 5학년 2학기에 제시되는 분수의 나눗셈과 소수의 나눗셈 단원을 나눗셈의 의미와 절차가 연결되도록 재구성한 뒤 수업을 실행하고 분석하였다. 연구 결과, 학생들은 수의 범위가 확장되더라도 나눗셈의 의미를 이해하여 문제를 해결하거나 만들 수 있었다. 또한 문제 해결 과정에서 자연수의 나눗셈, 분수의 나눗셈, 소수의 나눗셈의 원리를 이용할 수 있었다. 단, 일부 학생들의 경우 나눗셈 의미를 이해하지 못하여 잘못된 나눗셈식을 세우거나 문제를 만들었으며, 특정한 해결 절차만을 선호하는 모습도 발견할 수 있었다. 본 연구를 통하여 초등학교 전 과정에 제시되는 나눗셈을 연결성을 강조하여 의미 있게 지도 학습할 수 있는 방향을 모색하는데 도움이 되기를 기대한다.

• 대한수학교육학회지:수학교육학연구
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• 제26권4호
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• pp.731-754
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• 2016

본 연구는 앎의 시점을 밝혀내기 위한 것이다. 앎의 시점이란 '모름'에서 '앎'으로 변화하는 인식의 과정에서 앎이 일어나는 시점을 의미한다. 인식의 과정을 파악하기 위해 초등학교 수학 교과서를 한 차시 단위로 하여 제시되는 질문을 분석하였다. 그 결과 교과서 속에서 앎의 시점을 판단할 수 있는 근거를 찾을 수 있었다. 첫째, 앎의 시점은 학습자가 '모를 것이다'라는 예상에서 '알 것이다'라는 기대로 바뀌게 되는 시점이다. 둘째, 교과서에서 학습자의 실질적 수행을 요구하는 질문에서 파악할 수 있다. 셋째, 차시의 수업 목표와 밀접하게 연결되어 있다. 넷째, 보조인식과 초점인식의 관계에서 초점인식에 해당된다. 다섯째, 개인화/배경화에서 탈개인화/탈배경화로 변곡 되는 시점에 해당된다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제6권4호
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• pp.205-212
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• 2001

One of the important characteristics of biological systems os their ability to change im-portant properties in response to small environmental signals. The molecular mechanisms that biological molecules utilize to sense and respond provide interesting models for the development of "smart" polymeric biomaterials with biomimetic properties. An important example of this is the protein coat of viruses, which contains peptide units that facilitate the trafficking of the virus into the cell via endocytosis, then out of the endosome into the cytoplasm, and from there into the nucleus, We have designed a family of synthetic polymers whose compositions have been de-signed to mimic specific peptides on viral coats that facilitate endosomal escape. Our biomimetic polymers are responsive to the lowered pH whinin endosomes, leading to distruption of the en-dosomal membrane and release of important biomolecular druges such as DNA, RNA, peptides and proteins to the cytoplasm before they are trafficked to lysosomes and degraded by lysosomal en-zymes. In this article, we review our work on the design, synthesis and action of such smart, pH-sensitive polymers.

• Journal of Microbiology and Biotechnology
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• 제26권5호
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• pp.876-882
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• 2016

Tylosin has been used as a livestock feed additive and antibiotic growth promoter for many years. However, the mode of action by which tylosin enhances animal growth is unclear. We used high-throughput sequencing of 16S rRNA genes to investigate the effects of tylosin as a feed additive on swine gut microbiota. No significant difference in the rate of weight increase was observed between control and tylosin-treated pigs during a 10-week feeding trial. However, tylosin-treated pigs showed rapid increases in the relative abundance of the phylum Firmicutes. Increases in Firmicutes species are associated with (so-called) obese-type gut microbiota. The abundance of species of four families of the phylum Firmicutes (Streptococcaceae, Peptococcaceae, Peptostreptococcaceae, and Clostridiaceae) correlated positively with host weight gain. The abundance of Streptococcaceae family bacteria was least affected by tylosin treatment. Distribution analysis of operational taxonomic units (OTUs) showed that both control and tylosin-treated pigs exhibited similar OTU alterations during growth. However, the tylosin-treated group showed distinctive alterations in gut microbiota when the host weighed approximately 60 kg, whereas similar alterations occurred at around 80 kg in the control group. Our results suggest that use of tylosin accelerates maturation of swine gut microbiota rather than altering its composition.

• Applied Biological Chemistry
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• 제36권3호
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• pp.191-196
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• 1993

본 연구는 합성기질인 $X-{\alpha}-Gal$를 이용하여 발효유 및 유제품내의 Bifidobacteria 생균수를 측정할 목적으로 하였다. 젖산균과 Bifidobacteria의 ${\alpha}-galactosidase$ specific activity를 측정한 결과 Bifidobacteria 균주에서는 높은 ${\alpha}-galactosidase$ activity를 가지고 있었으며, 그 중 Bif. longum KCTC 3215의 specific activity는 8.57 unit/mg protein으로 가장 높게 나타났다. Lactobacillus, Streptococcus, Pediococcus와 Leuconostoc 균주에서는 활성이 미약하거나 없었다. 합성기질인 $X-{\alpha}-Gal$을 MRS agar 배지에 $100{\;}{\mu}M$ 첨가한 결과 Bifidobacteria는 blue colony로, Lac. bulgaricus, Lac. casei와 Leu. mescenteroides 균주는 light blue colony로, 그 외 젖산균에서는 white colony로 나타났다.

• 한국콘텐츠학회논문지
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• 제9권1호
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• pp.446-454
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• 2009

본 논문에서는 학습활동 중심의 컴포넌트를 기반으로 설계 구현한 u-러닝 허브사이트 시스템을 제안한다. 제안된 시스템은 u-러닝 환경에서 다양한 단말기를 통하여 교육활동이 이루어 질수 있도록 u-러닝 허브사이트의 기능을 컴포넌트 단위로 세분화 하며, 각 컴포넌트는 클래스들의 상속과 조합을 통하여 실시간으로 허브 사이트의 기능을 구성한다. 즉 접속하는 단말기와 프로그램의 특성을 파악하여 기본이 되는 부모 클래스를 바탕으로 자식 클래스를 추가하거나 조합하여 하나의 컴포넌트를 동적으로 구성하게 된다. 이러한 방식을 통해, 본 논문에서 제안한 시스템은 다양한 단말기를 지원 할 수 없는 기존의 e-러닝 시스템과 달리 동일한 시스템 하에서 시간, 장소, 단말기와 프로그램에 구애받지 않고 교육활동 서비스를 이용할 수 있는 유비쿼터스 러닝 환경을 제공한다.

• 한국산학기술학회논문지
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• 제13권3호
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• pp.1337-1345
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• 2012

한반도 전구에서 적용되고 있는 EBO의 핵심교리는 측정 가능한 효과를 선정하여 최소의 전투로 승리하는 것이다. 이러한 EBO 교리를 고찰하여 무기체계 획득에 요구되는 방법론으로 V-C 연동체계 하에서의 효과분석 방법론을 연구 제시하였다. 제시된 방법론은 먼저 편성된 무기체계의 효과 정보를 확인하고 분석목적을 고려하여 MOE와 MOP, 효과를 설정하며 적정 무기체계의 운용개념과 시나리오 등을 적용하고 가용 C모델로 사후분석 조정 환류 하는 것이다. V-C 연동체계는 가상 합성 전장 환경에서의 실시간 전투실험을 가능케 한다. 이러한 V-C 연동체계에서 미래 대전차 유도무기체계의 방어전투 편성과 배치 등을 고려한 모델링으로 대대급 작전으로 중대급 개체를 운용하는 시나리오를 작성, AWAM을 구현하여 효과를 분석하고 SBA 토대를 구축하였다.

• 한국농공학회지
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• 제17권3호
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• pp.3878-3884
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• 1975

This study was carried out to develop the throw-in type thresher with its size as small as possible. Developing the smallest possible size of the throw-in type thresher has been very important to increase mobility and to reduce the machine price. The thresher that developed for this purpose was tested as to threshing and separation performance for the samples collected in eight catch boxes under the concave while threshing. The amount of grain collected in each compartments was measured and the threshing and separating pattern along the total span of the threshing drum was determined. The performance of separating and threshing units of the test thresher and threshing loss was evaluated by use of the developed grain separating apparatus and the method for measuring the grain separating performance of threshers. The results are summarized as follows; 1. The unthreshed grain (drum losses) and semi-threshed grain did not appeared at all throughout the treatments. 2. When threshed by making use of the developed throw-in type thresher, the threshing grain loss at about 25 per cent grain moisture was about one-half when threshed at about 18 per cent grain moisture. 3. And its grain separating loss in higher feed rate was decreased in comparison with that of lower feed rate. These results suggests that the throw-in type thresher may be suitable for wet threshing and for higher feed rate of threshing. 4. Above 60 per cent of total grain passing through concave fell through the screen within a scant 30 cm from the feeding inlet. This threshing pattern may suggest that major threshing action may be finished before about one third of cylinder length. The required separating load extended over the whole drum span is so defferent that separating elements should be redesigned so as to accomodate this variable pattern of separation load. 5. It was apparent from the experiment that the length of the threshing drum of the throw-in type thresher could be reduced from 1285mm to about 1050mm without increasing grain separation loss greatly.

• Journal of Plant Biology
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• 제20권2호
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• pp.91-101
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• 1977

Using barley seeds (Hordeum sativum Jess, var.), the influences of gibberellic acid (GA) and indole-3-acetic acid(IAA) on the amylase synthesis and that of the nucleic acid metabolism were investigated. 1. With the deembrynized barley seeds, the increase of amylase treated with a $10^{-5}M$ of GA and the decrease of amylase treated with $10^{-5}M$IAA were matched by a proportionate increase and decrease in the amount of RNA. The influence of the hormones on the RNA synthesis has appeared immediately after the treatment but on the amylase synthesis it has appeared 8 hours later. But no influence on the DNA synthesis was observed on both hormones. 2. The amylase from deembryonized barley seeds treated with GA and IAA have been fractionated by gel filteration on Sephadex G-100. The amylase components showed four fractions on both enzymes treated with GA and IAA. Fraction I(FI) was differed from fraction Ⅵ(FIV) in Km value and the effects of temperature, pH and metal ions. On the basis of their emzymatic properties, it was considered that the FI was $\beta$-amylase and FIV was $\alpha$-amylase. The influences of GA and IAA on each fractions appeared to be similar but on the amylase units per souble protein, IAA inhibited the production of amylase FIV while it promoted that of amylase FI. 3. An experiment was conducted to determine whether IAA inhibits GA-promoted amylase synthesis competitively or non-competitively. Using a Lineweaver-Burk plot, it was clear that IAA was acting in a non-competitive fashion. From this, IAA was probably not competing with GA at the same site, but it was acting at some other site which resutled in partial blocking of the action of GA on the amylase synthesis.

• Journal of Microbiology and Biotechnology
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• 제2권3호
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• pp.189-196
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• 1992

A $\alpha$-l, 4-D-glucan maltohydrolase $(\beta$-amylase), secreted by the mesophilic aerobic bacterium Bacillus polymyxa No.26, was purified and characterized. The enzyme production was increased after a logarithmic phase of bacterial growth and paralleled with the onset of bacterial sporulation. By applying anion exchange chromatography and gel filtration the enzyme was purified 16.7-fold and had a specific activity of 285.7 units/mg. Two enzyme activities were eluted on a column of DEAE-Sephadex chromatography, and they were designated as E-I for a major enzyme peak and E-II for a minor peak. Of them, E-I enzyme peak was further purified by using gel chromatography. The molecular mass of this enzyme was determined to be 64, 000 daltons and consisted of a single subunit, showing an isoelectric point of 8.9. The enzyme was able to attack specifically the $\alpha$-l, 4-glycosidic linkages in soluble starch and caused its complete hydrolysis to maltose and $\beta$-limited dextrin. This amylolytic enzyme displayed a temperature optimum at $45^\circ{C}$ and a pH optimum at 7.0. The amino acid composition of the purified enzyme was quite similar to the other bacterial $\beta$-amylases reported. Surprisingly, the purified enzyme from this aerobe only exhibited hydrolytic activity on soluble starch, not on starch granules. The degradation of from starch by $\beta$-amylase was greatly stimulated by pullulanase addition. These results differentiated from other $\beta$-amylases reported. Based on a previous result that showed the enzyme system involves in effective degradation of raw starch granules, this result strongly suggested that the purified enzyme (E-I) can be a synergistic part of starch granule-digestion and E-II plays a crucial role in digestion of starch granules.