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경남지역 밭 토양 화학성분이 미생물 생태에 미치는 영향
이영한(Young-Han Lee),하상건(Sang-Keun Ha) 한국토양비료학회 2011 한국토양비료학회지 Vol.44 No.2
경남지역 밭 토양 25개소를 대상으로 2009년에 토양 화학성분과 미생물 다양성을 검토하고 토성, 지형 및 작물별 주요 변동요인을 주성분분석으로 해석하였다. 토양 유효인산 및 치환성 칼륨과 칼슘 함량은 적정수준 보다 높았으며 대부분의 토양 화학성분이 최소값과 최대값의 차이가 크게 나타났다. 지형적으로 산록경사지는 토양 유기물 함량과 치환성 칼륨 함량이 유의적으로 높았고 (p<0.05) 토성별 유기물 함량은 양토에서 높은 반면에 염류농도와 유효인산 함량은 사양토에서 높았으며 고구마 재배지의 치환성 칼슘함량은 감자 재배지에 비해 유의적으로 높았다. 지형별 밭 토양의 곰팡이 개체수는 곡간 및 선상지가 하성평탄지 보다 유의적으로 많았고 토양 미생물체량과 탈수소효소 활성은 산록경사지가 다른 지형에 비해 유의적으로 높았다(p<005). 토성에 따른 토양의 coliform 그룹은 미사질양토가 사양토와 양토에 비해 유의적으로 높았고 미생물체량은 양토가 미사질양토 보다 유의적으로 높았으나 (p<005) 작물별 미생물상과 토양 미생물체량 및 탈수소효소 활성은 유의적인 차이가 없었다. 주성분 분석결과 제1주성분이 32.2%, 제2주성분이 24.2%로서 전체 56.4%의 자료를 설명할 수 있었으며 제1주성분은 토양의 유효인산 함량이 가장 크게 기여하였다. 토양 바실러스균과 곰팡이균은 토양의 유기물 함량과 정의 상관관계를 보였으며 토양 pH는 형광성 슈도모나스균과 정의 상관관계를 나타냈다. Soil management for environment-friendly agriculture depends on the effects of soil microbial activities and soil fertility. To improve soil health for the upland crops, this study evaluated a relationship between soil chemical properties and soil microbial diversities at 25 sites in upland soils in Gyeongnam Province. The average nutrients in the upland soils were 1.7 times for available phosphorous, 1.4 times for exchangeable potassium and 1.5 times for exchangeable calcium higher compared to recommend concentrations in the upland soils. We found a significant positive correlation between the soil organic matter and the soil microbial biomass C (p<0.01). Contents of organic matter and dehydrogenase in the inclined piedmont soils were significantly higher than those in the other topographical soils (p<0.05). In addition, concentrations of organic matter and microbial biomass C in the loam soils were significantly higher than in the silt loam soils (p<0.05). In principal component analyses of chemical properties and microbial populations in the upland soils, our findings suggested that available phosphorous should be considered as potential factor responsible for the clear upland soils differentiation. The soil organic matter was positive correlation with Bacillus sp. and fungi, whereas soil pH was also positive correlation with Pseudomonas sp. in upland soils.
200㎫급 초고강도 콘크리트의 자기수축 특성에 관한 실험적 연구
하정수(Ha Jung-Soo),백민수(Paik Min-Su),손유신(Sohn Yu-Shin),이승훈(Lee Seung-Hoon),이영도(Lee Young-Do),정상진(Jung Sang-Jin) 대한건축학회 2011 大韓建築學會論文集 : 構造系 Vol.27 No.8
Low W/B ultra-high strength concrete has low porosity and discontinuous capillary tube in the cement milk. Within a few days after placement, autogenous shrinkage occur because of the quick drying from the self-desiccation. So, the possibility of cracking is higher than the normal strength concrete. In this study, the autogenous shrinkage deformation characteristics of ultra-high strength concrete that are different from the normal strength concrete were examined. A new shrinkage formula is suggested form the experiment data. The conclusion is as follows. 1) The 91days strength of the concrete combination that are W/B 12.5%, normal portland cement 55%, china silica fume 20%, GGBFS-2 20%, anhydrite 5% was the best result, 193.7㎫. So, it is the appropriate combination for the 200㎫ grade ultra-high strength concrete. 2) The autogenous shrinkage deformation of W/B 20% ultra-high strength concrete can be predicted using the suggested shrinkage formula.
순환잔골재의 수분공급에 의한 고강도 콘크리트의 자기수축 저감
하정수 ( Ha Jung-soo ),김한식 ( Kim Han-sic ),조현준 ( Cho Hyun-jun ),이영도 ( Lee Young-do ) 한국건축시공학회 2017 한국건축시공학회 학술발표대회 논문집 Vol.17 No.2
This study aims to achieve an enhancement in the quality of high strength concrete through a reduction in autogenous shrinkage by supplying the moisture needed for hydration through recycled aggregates that retain high amounts of moisture. The result showed that, moisture supply increased with the higher replacement rate, autogenous shrinkage dropped by up to 60 percent. Also, compressive strength was increased by up to 10 percent.
생산성 및 품질향상을 위한 방수공사의 장비 활용 시공기술
김한식,하정수,이영도,Kim, Han-Sic,Ha, Jung-Soo,Lee, Young-Do 한국건축시공학회 2023 한국건축시공학회지 Vol.23 No.4
This research investigates the deployment of waterproofing technologies in construction, with a specific focus on augmenting worker safety, work environment, and solve the difficulty of securing skilled workers. Implementing liquid waterproofing cement equipment resulted in a remarkable increase in adhesion performance by around 20%, coupled with a twofold acceleration in operational speed. The application of primer spraying apparatus led to a two-fold improvement in both penetration and adhesion performance, concurrently boosting the work speed by approximately the same factor. With urethane spraying equipment, the workload could be reduced to a third for the same layer thickness, adhesion performance enhanced by approximately 1.4 times, and workability improved by about 1.4 to 1.5 times. These findings suggest that such technological interventions can potentially enhance work efficiency, improve the quality of output, and mitigate safety accidents that are commonplace in manual operations. Furthermore, these advancements present promising solutions to the ongoing challenges of sourcing highly-competent workers in the industry.