• 공학교육연구
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• 제12권1호
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• pp.31-41
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• 2009

과학기술의 발전이 가속화되고 사회에 미치는 파급력이 커짐에 따라 과학기술자의 사회적 책임 향상과 전문직 윤리에 대한 관심이 높아지고 있다. 공학분야에서는 특히, EC2000의 도입과 공학교육인증기준이 체계화와 더불어 공학윤리교육의 중요성이 강조되고 있다. 하지만 공학과 윤리의 결합은 단순히 원칙적 선언에 의해 확보될 수 없으며 교육 시스템안에서 어떻게 제도화될 수 있고 실행 가능한 지에 대한 체계적 접근이 필요하다. 이 연구는 공학윤리 교육 제도화의 전제 조건이 되는 인식의 전환과 공학의 일상적 경험에 근거한 윤리 교육이 필수적임을 주장하고 있다. 1980년대까지 확립된 공학윤리교육의 의의와 한계를 밝히면서 최근 발전하고 있는 공학윤리교육의 특성과 지향점을 살펴본다. 또한 현재 이루어지고 있는 공학윤리교육의 유형을 분석하여 각 유형별 쟁점과 특성을 분석한다. 이제 막 발전하기 시작한 우리나라의 공학윤리교육은 각 대학의 주어진 여건과 상황을 고려하여 독립형 혹은 전공결합형 공학윤리 교육을 적절히 조합하여 추진하는 것이 바람직하다. 무엇보다 공학과 공학 이외 분야의 해당 전문가들 사이의 협력 연구와 교육이 선행되어야 할 것이다.

• Journal of Ecology and Environment
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• 제30권4호
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• pp.341-346
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• 2007

Nest density was determined and tree and soil characteristics around Nycticorax nycticorax breeding sites and non-breeding sites on Bamsum Island in Seoul were analyzed from May 2005 to October 2006 to identify breeding site preferences of N. nycticorax and the effects of N. nycticorax nesting density on nesting tree structure and soil characteristics. N. nycticorax preferred trees of low height ($3.5{\sim}6$ m) and small diameter at breast height in high density Salix communities. Excrement of heron juveniles was dropped on the soil under the nests. The soil nutrient content under nests (P: 126.0 mg/kg, N: 202.8 mg/kg, EC: 549 ${\mu}S/cm$, pH 4.7) was much higher than that of control soils from Bamsum Island not enriched by heron excrement (P: 41.5 mg/kg, N: 42.0 mg/kg, EC: 342 ${\mu}S/cm$, pH 5.1). Formation of Salix communities on the shores of Bamsum Island is ongoing, and their structure has been directly influenced by annual flooding. After flooding, the nutrient content differences between heron-affected soils and control soils were not significant. This might be the reason that Salix communities on Bamsum were not affected by nesting herons as in other terrestrial communities where herons nest. This result indicates that flooding plays an important role in sustaining Salix communities on Bamsum Island where herons nest. The results of this study may increase understanding of N. nycticorax breeding behavior which may be useful for conservation planning.

• Journal of Microbiology and Biotechnology
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• 제26권2호
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• pp.337-346
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• 2016

Three combinations of molecular chaperones from Escherichia coli (i.e., DnaK-DnaJ-GrpE-GroEL-GroES, GroEL-GroES, and DnaK-DnaJ-GrpE) were overproduced in E. coli BL21, and their in vitro stabilizing effects on a nitrile hydratase (NHase) were assessed. The optimal gene combination, E. coli groEL-groES (ecgroEL-ES), was introduced into Rhodococcus ruber TH3. A novel engineered strain, R. ruber TH3G was constructed with the native NHase gene on its chromosome and the heterologous ecgroEL-ES genes in a shuttle plasmid. In R. ruber TH3G, NHase activity was enhanced 37.3% compared with the control, TH3. The in vivo stabilizing effect of ecGroEL-ES on the NHase was assessed using both acrylamide immersion and heat shock experiments. The inactivation behavior of the in vivo NHase after immersion in a solution of dynamically increased concentrations of acrylamide was particularly evident. When the acrylamide concentration was increased to 500 g/l (50%), the remaining NHase activity in TH3G was 38%, but in TH3, activity was reduced to 10%. Reactivation of the in vivo NHases after varying degrees of inactivation was further assessed. The activity of the reactivated NHase was more than 2-fold greater in TH3G than in TH3. The hydration synthesis of acrylamide catalyzed by the in vivo NHase was performed with continuous acrylonitrile feeding. The final concentration of acrylamide was 640 g/l when catalyzed by TH3G, compared with 490 g/l acrylamide by TH3. This study is the first to show that the chaperones ecGroEL-ES work well in Rhodococcus and simultaneously possess protein-folding assistance functions and the ability to stabilize and reactivate the native NHases.

• 산업융합연구
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• 제21권3호
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• pp.195-202
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• 2023

본 연구는 학습자의 교육적 요구를 파악하기 위해 현장에서 이루어진 수업을 바탕으로 설문조사 결과를 분석하여 SW 교육에 필요한 요소를 반영하기 위한 것이다. 본 연구에서는 선행연구를 통해 학습 동기와 학습 성취도에 따른 다양한 실험적 요소를 구성하고 설계하였다. 본 연구에 적용한 설문조사로 교수자 역량(FC), 학습자 역량(LC), 교육 여건(EC)의 3가지 부문의 실험적 요소를 1차 영역별, 2차 전공 계열별로 각각 분석하였다. CT 기반의 SW 교육을 영역별로 분석한 결과 교육자료 개발, 강의에 대한 이해, 교수방법은 만족도가 높게 나타난 반면, 수강생과의 소통, 강의의 난이도, 수강 인원은 상대적으로 낮게 나타났다. 전공별로 분석한 결과는 인문 계열에서 공학 계열보다 어렵고 흥미가 떨어지는 것으로 결과가 나타났다. 본 연구에서는 이러한 통계적 결과를 바탕으로 학습자의 문제해결 능력 향상 측면에서 향후 효과적인 교양교육을 위하여 흥미로운 교과과정으로 비전공 SW 교육이 개선되어야 할 필요성을 제시한다.

• Journal of Microbiology
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• 제45권2호
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• pp.153-157
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• 2007

5-enolpyruvylshikimate-3-phosphate synthase (EPSP synthase, EC 2.5.1.19) is the sixth enzyme in the shikimate pathway which is essential for the synthesis of aromatic amino acids and many secondary metabolites. The enzyme is widely involved in glyphosate tolerant transgenic plants because it is the primary target of the nonselective herbicide glyphosate. In this study, the Dunaliella salina EPSP synthase gene was cloned by RT-PCR approach. It contains an open reading frame encoding a protein of 514 amino acids with a calculated molecular weight of 54.6 KDa. The derived amino acid sequence showed high homology with other EPSP synthases. The Dunaliella salina EPSP synthase gene was expressed in Escherichia coli and the recombinant EPSP synthase were identified by functional complementation assay.

• Elastomers and Composites
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• 제53권2호
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• pp.48-51
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• 2018

10, 20, 30, and 40% of polyvinyl chloride (PVC) were added to nitrile butadiene rubber (NBR) to modify the latter. The NBR/PVC composites containing pure NBR were synthesized to investigate properties, such as crosslinking density, hardness, tensile strength, abrasion resistance, heat resistance, solvent resistance, and filler dispersion. The experimental result revealed a decrease in crosslinking density and heat resistance with increase in the PVC content. In contrast, addition of PVC to NBR resulted in enhancement of hardness, tensile strength, solvent resistance, and filler dispersion.

• Elastomers and Composites
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• 제54권4호
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• pp.279-285
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• 2019

Bio-based polyester polyols were synthesized using esterification with azelaic acid, sebacic acid, and 1,3-propanediol. Polyurethanes were prepared using chain extenders (1,4-Butanediol, 1,3-Propanediol, and isosorbide) and 4,4'-diphenylmethane diisocyanate with a mixing ratio of 1:1:1.1. Subsequently, the properties of the polymers prepared using the different chain extenders were compared. The synthesis of polyurethane was confirmed by FT-IR, TGA, and GPC. The mechanical properties (hardness, ball rebound, and tensile strength) of the materials were analyzed using shore A tester, taber abrasion, and UTM. heat, chemical, and water resistances of the prepared materials were measured by comparing the tensile strengths according to external changes.

• Elastomers and Composites
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• 제54권1호
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• pp.35-39
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• 2019

Four different polymer compounds were prepared from four kinds of plasticizers, viz. di-2-ethylhexyl azelate (DOZ), di-2-ethylhexyl adipate (DOA), di-2-ethylhexyl sebacate (DOS), and di-2-butyl sebacate (DBS), for making cable sheaths for ships. Ethylene-vinyl acetate and ethylene-propylene-diene-copolymer as matrix polymers and ethylene-vinyl acetate grafted maleic anhydride as a coupling agent were compounded with a flame retardant, crosslinking agent, filler, and other additives, besides the plasticizer to obtain the polymer compounds. The polymer containing DOZ showed the highest MH and ${\Delta}T$ in the rheology test, while that containing DBS was found to have the lowest tensile strength and highest elongation because of low ${\Delta}T$. The four polymers showed similar values (31.7-31.9) for flame resistance, while the polymer containing DOZ showed the highest value for cold resistance.

• Elastomers and Composites
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• 제54권2호
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• pp.118-122
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• 2019

Four different polymer compounds were manufactured to make cable sheaths for the shipping industry. Two kinds of ethylene vinyl acetate (EVA) as the main matrix polymers and EVA-grafted maleic anhydride (EVA-g-MAH) as the coupling agent were selected for compounding with fire retardant, crosslinking agent, filler, plasticizer, and other additives. The properties of the four compounded materials were investigated with different contents of the fire retardant, silanecoated magnesium dihydroxide (S-MDH). In the rheology evaluation, the $t_{60}$ and ${\Delta}T$ values increased with increasing S-MDH contents. On the other hand, the tensile strength decreased with increasing S-MDH content due to a relative decrease in binder polymers. With increasing S-MDH content, fire resistance increased, but cold resistance showed no obvious enhancement due to the polar effect of vinyl acetate in EVA.

• 환경생물
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• 제42권1호
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• pp.54-61
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• 2024

생태계는 생물에게 매우 다양한 환경조건의 서식처를 제공하며 이 서식처 내에 적응한 생물만이 생존, 성장, 번식하며 해당 서식처에 살아가게 된다. 또한 서식처의 환경조건들은 서식처로 유입한 화학물질의 생물유효도(bioavailability)에 크게 영향을 미쳐 생물들이 받는 부정적 영향이 서로 다를 수 있다. 본 연구에서는 생태독성평가에 적합한 ISO guideline 11276의 독성평가 표준종 중 토양 생태계에 다양한 서식처 조건 중 수변 생태계에서 적응하여 살아가는 Yuukianura szeptyckii의 중금속에 대한 평가 민감성을 확인하고 수변 서식처 중금속 생태독성평가종으로서의 가능성을 확인하는 데 있다. 결과는 카드뮴과 구리 모두 농도에 따른 유의한 독성영향을 보였다. 카드뮴의 경우 LC₅₀은 280 mg kg^-1, EC₅₀은 66 mg kg^-1, NOEC와 LOEC는 각각 25, 50 mg kg^-1으로 나타났으며 구리의 경우에는 LC₅₀은 911 mg kg^-1, EC₅₀은 151 mg kg^-1, LOEC는 50 mg kg^-1으로 나타났다. 기존의 국제표준종인 Folsomia candida와 국내표준종인 Allonychiurus kimi의 이전 결과와 비교하면 더욱 민감한 독성값을 보였으며, 이러한 생존과 번식에 미치는 부정적 영향은 체내의 중금속의 유입 농도와 밀접한 관련을 보였다. Y. szeptyckii는 수분 함량이 높은 토양에서 중금속 생태독성평가에 민감한 종으로 나타났으며, 상대적으로 높은 습도를 보일 가능성이 높은 수변생태계에 적합한 생태독성평가종으로 사용이 가능할 것으로 생각된다.