• 공업화학
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• 제5권5호
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• pp.786-794
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• 1994

폴리머-시멘트 모르타르의 강도와 내구성에 대하여 검토하였다. 폴리머-혼화제로서 styrene-butadiene rubber(SBR) 라텍스, ethylene-vinyl acetate(EVA) 에멀젼 및 polyacrylic ester(PAE) 에멀젼을 사용하고, 폴린머-시멘트 비를 다양하게 변화시켜(5, 10, 15, 20 wt%) 공시체를 제작하였다. 내구성의 평가시험으로는 동결융해시험, 내산성시험 및 내열성 시험을 수행하였다. 폴리머-시멘트 모르타르의 내동해성은 폴리머-시멘트비가 증가될수록 현저히 향상되었으나 내산성과 내열성은 저하되었다. SBR 폴리머-시멘트 모르타르의 강도(압축 및 휨강도)는 폴리머-시멘트비가 증가될수록 향상되었으나 EVA 및 PAE 폴리머-시멘트 모르타르는 폴리머-시멘트비 10wt%에서 최대치를 나타내었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.707-714
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• 2001

This paper presents the fundamental study on rational manu(acture of Very High Strength(VHS) concrete using industrial by-products as like silica fume, slag and fly ash. In this study, we had tested various mixing cases to manufacture the VHS concrete(target compressive strength : over 1,000 kgf/$cm^{2}$) which is easily workable (target slump flow : 60$\pm$l0cm), The main variables studied are; 1) test variables to find the optimum replacement ratio of mineral admixture, 2) test variables to find a rational water-binder ratio, a proper binder content, 3) test variables to find the method for reduction of slump loss, 4) test variables to know the influence of air entrainment on frost resistance. From the test results, it is concluded that the rational mix design can be made by using 40% slag, 10% silica fume, and water reducing agent(slump loss reduction type). We found that it is unnecessary to entrain air for freeze-thawing resistance.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.449-454
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• 1999

Pavement concrete subjected to severe environmental condition may be vulnerable to frost attack practically where de-icing chemicals are used. This study focused on the investigation of durability characteristics of pavement concrete incorporation polypropylene fibers and application feasibility of these into the pavements of local roads and highway. A series of labortory tests were performed with main experimental variable such as fiber types, fiber contents. and type of concrete mix. The test of compressive strength was executed as primary tests, before the durability tests such as a scaling resistance were performed. De-icing salt resistance test was progressed by recycling freeze and thaw in the presence of a 4% calcium chloride solution. The deteriorated surfaces were rated by visual inspection and the loss weight were measured at every 5 cycles.

• 한국세라믹학회지
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• 제45권11호
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• pp.719-724
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• 2008

Every concrete structure should continue to perform its intended functions such as to maintain the required strength and durability during its lifetime. Deterioration of the concrete structure, however, occurs more progressively from the outside of the concrete exposed to severe conditions. Main deteriorations in concrete structures result from carbonation, chloride ion attack and frost attack. Concrete can therefore be more durable by applying surface protection to increase its durability using impregnants, which are normally classified into two large groups in polymeric and silicate materials. Concrete impregnants are composed of silanes and alkali silicates (sodium, potassium and lithium silicate). Thus, this study is concerned with elevating the carbonation and Cl- penetration resistance of concrete structures by applying alkali silicate hydrophilic impregnants including lithium and potassium silicates. From the experimental test results, lithium and potassium silicates produced a good improvement in carbonation resistance and are expected to be used as hydrophilic impregnants of concrete structures.

• 한국산학기술학회논문지
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• 제17권1호
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• pp.111-118
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• 2016

스케일링은 겨울철 제설제 살포 및 동결융해의 복합작용으로 인하여 교통시설 구조물에서 발생하는 대표적인 콘크리트의 성능저하 현상이다. 본 논문에서는 콘크리트의 스케일링 저항성에 영향을 미치는 요인을 분석하기 위하여 콘크리트의 역학적 성능, 공극구조 특성과 스케일링 저항성과의 관계를 실험적으로 고찰하였다. 실험결과, 콘크리트의 스케일링 저항성은 콘크리트의 압축강도와는 그다지 상관관계가 적었으며, 오히려 콘크리트의 표면투수 특성과 밀접한 관련이 있는 것으로 조사되었다. 또한, 콘크리트의 스케일링 저항성을 평가하기 위한 파라미터로써, 기포 간극계수 및 비표면적은 적합하지 않은 것으로 나타났다. 한편, 결합재의 종류에 따른 스케일링 저항성도 상이하게 나타났으며, 보통포틀랜드시멘트 콘크리트 및 실리카흄 콘크리트에 비하여 고로슬래그미분말을 사용한 콘크리트의 스케일링 저항성이 상대적으로 낮은 것으로 나타났다.

• International Journal of Industrial Entomology and Biomaterials
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• 제33권2호
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• pp.41-49
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• 2016

We bred a mulberry cultivar named Shimgang, through local adaptability test, which is under registration as a new cultivar for fruit production. Local adaptability test had been carried out at four local places(Suwon, Chuncheon, Buan and Jinju) for five years from 2011. This variety 'Shimgang' belongs to Morus Microphylla Buckl. selected from seedlings imported from USA. Shimgang was resistant to popcorn disease and high yielding variety in fruit productivity by 111% compared to control cultivar 'Shimheung(Morus alba L.)' for three years. Although fruits of 'Shimgang' was smaller in size and lower in sugar content of mulberry fruits, it showed stronger resistance than that of 'Shimheung'. It is adaptable to every where except the places where cold and late frost damage happen frequently.

• 한국식품영양과학회:학술대회논문집
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• 한국식품영양과학회 2004년도 Annual Meeting and International Symposium
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• pp.185-197
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• 2004

Type 2 diabetes is characterized by hyperglycemia and hyperinsulinemia, features of insulin resistance. In vivo treatment of ob/ob mice with hydrolyzed fibroin reverses these pathological attributes (6). To explore the mechanism underlying this effect, we have used the 3T3-Ll adipocytes as a cell type which would represent the periphery, in vivo. Exposure of 3T3-Ll adipocytes to chronic insulin leads to the a 50% loss of insulin-stimulated glucose uptake. Chronic exposure to fibroin blocked, in part, the response to chronic insulin but also increased the sensitivity of control cells to the acute action of insulin. The later effect was most robust at physiological concentrations of insulin. Fibroin did not prevent the insulin-induced down-regulation of the insulin receptor or the tyrosine kinase activity associated with the receptor. Further, fibroin had no affect on the loss in activity of the insulin-sensitive down-stream kinase, Akt. Interestingly, fibroin accelerated glucose metabolism and glycogen turnover independent of insulin action. In addition, fibroin up-regulated GLUT1 which increased its expression at the cell surface and caused the redistribution of GLUT4 to the plasma membrane. Together, these later effects would lead to an improvement in hyperglycemia in vivo which would in turn reduce the need for insulin.

• 한국유체기계학회 논문집
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• 제19권3호
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• pp.43-47
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• 2016

Pile foundations constructed on extremely cold regions cause serviceability problems of superstructures from repeated actions of ground freezing and thawing. Oil sand module plants are mainly constructed on seasonal frozen ground. Due to the freezing and thawing actions of grounds, vertical movements of piles have been observed. To solve these erratic pile movement problems, thin vertical layer of PET aggregates is installed around the pile shaft to prevent potential unfavorable pile movements. There is no known method to calculate "thin PET aggregate layer" -surrounded pile shaft resistance (capacity) against vertical loads; therefore, this experimental research is conducted. Specifically, in this study, horizontal (normal) pressures on pile shaft were assessed varying PET aggregate layer thickness based on the experiment.

• 한국산림과학회지
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• 제27권1호
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• pp.1-4
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• 1975

한국에 가장 유망한 사과 재배품종(栽培品種) 중(中)에서 가장 큰 내한성도(度)를 갖인 품종(品種)을 선택하기 위하여 내한성도(耐寒性度)가 측정(測定)되었다. 왜성대목(矮性臺木)으로 사용(使用)되는 두 품종의 내한성도(耐寒性度)도 재배품종과 비교하기 위해 측정되었다. 부위별(部位別) 내동성도(耐凍性度)는 EM26을 제외한 모든 품종(品種)에서 동아(冬芽), 형성층(形成層), 임부유조직(林部柔組織) 및 피층(皮層)의 순위(順位)로 증가(增加)하였다. 품종간(品種間)의 내한성도(耐寒性度)의 순위(順位)는 부위별(部位別)로 일정(一定)치 않았으나 재배품종(栽培品種) Nugget Spur 만은 모든 부위(部位)에 있어서 가장 낮은 내한성도를 보였다. 가장 내한성도가 높은 품종(品種)과 만상(晩霜)의 피해에 강(强)한 품종을 선택하는데 있어서 품종내(品種內) 부위간(部位間)의 내한성도(耐寒性度)의 차이(差異)에 관(關)하여 고찰(老察)되었다.

• 한국건설순환자원학회논문집
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• 제9권4호
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• pp.419-424
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• 2021

콘크리트의 압축강도 추정에 널리 사용하는 반발경도법을 이용하여 콘크리트 표면의 동해손상을 초기에 판정할 수 있는 가능성을 검토하고자 하였다. 이를 위하여 동결융해 열화조건에 다면으로 노출된 콘크리트와 단면으로 노출된 콘크리트에 대하여 반발경도와 상대동탄성계수를 측정하여 콘크리트 표면 손상도를 비교하였다. 반발경도에 의한 동해손상이 단면 노출 콘크리트 시험체에 대해서는 150싸이클 빠르게 계측되었으며, 다면 노출 시험체에 대해서는 50싸이클 빠르게 계측되었다. 따라서 반발경도법이 공명진동법보다 콘크리트 표면 손상을 신속하게 판정할 수 있는 것으로 사료된다