Concrete has been recognized as a material which is resistant to the high temperature, but chemicophysical property of concrete is changed by the high temperature. So, mechanical properties of concrete may be reduced. Therefore, concrete is evaluated mechanical properties for safety inspection. However, research of ultrasonic pulse method is not much. Therefore, the purpose of this study is to Non-Destructive Test of 30, 70, 110MPa concrete exposed high temperature using ultrasonic pulse velocity.

Concrete has been recognized as a material which is resistant to the high temperature, but chemicophysical property of concrete is changed by the high temperature. So, mechanical properties of concrete may be reduced. Therefore, concrete is evaluated mechanical properties for safety inspection. However, research of ultrasonic pulse method is not much. Therefore, the purpose of this study is to Non-Destructive Test of 30, 70, 110MPa concrete exposed high temperature using ultrasonic pulse velocity.

초고강도 콘크리트를 이용한 부재의 내화 성능을 검토하기 위해서는 실제부재 단위의 시험에 의한 평가가 요구되고 있다. 그러나 실제부재 실험을 하기 위해서는 재하 능력이 큰 시험 장비가 필요하기 때문에, 재료 모델을 이용한 해석적 연구를 통해 내화 성능을 평가하고 있다. 본 연구에서는 80, 130 및 180 MPa의 초고강도 콘크리트를 대상으로 고온 가열시의 변형 특성을 실험적으로 평가하고 초고강도 콘크리 트에 대한 기존 변형 모델의 적용을 검토했다. 그 후, 최소 제곱법에 의해 실험 값과 기존의 변형 모델을 적용한 계산 값의 누적 오차가 가장 작 은 상수 값을 도출하고 초고강도 콘크리트에 적용 할 수 있는 변형 모델을 제시했다.

Background : The hypoglycemic effects of mulberry leaves extract were evaluated by comparing the abilities on glucose uptake in C2C12 myotubes and 3T3-L1 adipocyte. Glucose uptake of the extracts were identified to be enhanced by bio-conversion using cellulolytic enzyme like Viscozyme. Methods and Results : The mulberry (Morus alba L) leaves were extracted with 30% ethanol or hot water. The hypoglycemic compounds such as Moracin C and, Quercetin and 1-Deoxynojirimycin were identified from the extracts of mulberry leaves. The extracts were fermented using kinds of celluolytic enzymes, which were vicozyme, pectinase, β-glucosidase and xylanase, in order to increase the contents of hypoglycemic constituents in the extracts. The hypoglycemic effects of the fermented extracts were evaluated by comparing the abilities on glucose uptake in C2C12 myotubes and 3T3-L1 adipocyte. The extracts of mulberry leaves fermented with only Viscozyme were identified to increase glucose uptake in C2C12 myotubes and 3T3-L1 adipocyte by supplement of the concentration of 10 μM extracts, compared to insulin as control. However, bio-conversion effects by other enzymes were not shown in the treatments, suggesting hypoglycemic constituents in the extracts of mulberry leaves can be conversed to more active compounds by cellulolytic enzyme treatment like viscozyme. Conclusion : From the above results, we may suggest that the hypoglycemic constituents in mulberry leaves extracts can be conversed to more active compounds by cellulolytic enzymes.

Recycled aggregate is not used the structures due to the negative perception of the quality. Using only recycled aggregate concrete structures to improve these recognition were constructed to evaluate the mechanical properties and durability. The result is determined to be applicable to 100% recycled aggregate concrete in the structure.

The purpose of this study was to evaluate the dynamic mechanical properties of fiber reinforced cement composite according to the strain rate. Experiment result, the compressive strength was improved by increase the strain rate. But strain at the peak stress and elastic modulus was not affected by the strain rate.

Thin plate amorphous steel fiber has more tensile strength and corrosion resistance than general steel fiber, and it has different fiber direction by casting direction. In this study, evaluating impact resistance and sectional crack characteristic of amorphous steel fiber-reinforced cement composites by casting direction.

In this study, local fracture of concrete was evaluated through high-velocity impact test. As results, increase of bending tension performance by fiber reinforcement did not affect penetration depth Control, but it decreased rear side fracture thickness and diameter. Therefore, it was observed that fiber reinforcement decreases scabbing limit thickness.

In this study, impact of high-velocity projectile by mixing steel fiber, polyamide, nylon, polyethylene fiber which have different shape and properties respectively. Scabbing is restrained because of micro-crack caused by the shock wave offset effect and energy dispersive of synthetic fibers are mixed populations.