• Journal of the Korea Concrete Institute
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• v.22 no.1
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• pp.123-130
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• 2010

In this study, mixed recycled coarse aggregate (RCA) was produced by mixing RCA from waste concrete in order to evaluate a new method of RCA production. Bond strength between reinforcing bars and RCA concrete was qualitatively evaluated as a part of continuous studies to establish design code of reinforced concrete structural members using recycled aggregate. For practical application, specimens were manufactured with the ready mix RCA concrete. Parameters investigated include: concrete compressive strength (i.e 21, 27 and 40 MPa), replacement levels (i.e 0, 30, 60 and 100%), bar position (i.e vertical and horizontal) and bar location (75 and 225 mm). For the pull-out test, each specimen was in the form of a cube, with each side of 150 mm in length and a deformed bar, 16 mm in diameter, was embedded in the center of each specimen. From the test results, the most of HT type specimen with compressive strength of 21 and 27 MPa showed lower bond strength than the ones provided in CEB-FIP and considered in reinforcement location factor ($\alpha\;=\;1.3$). It was reasoned that bonded area of top bar specimen was reduced at the soffit of reinforcement because of bleed water of fresh concrete. Therefore the reinforcement location factor in current KCI design code should be reviewed and modified.

• Herbal Formula Science
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• v.17 no.2
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• pp.65-72
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• 2009

Objectives : Yukmijihwang-tang (YJT) is known as a tonifying formula for reinforcement of yin deficiency conditions. The present study was carried out to investigate the potential acute toxicity of YJT in ICR male and female mice. Methods : We investigated the acute toxicity about boiling water-extracted YJT. The test article was orally administered once by gavage to 20 male and 20 female mice at dose levels of 0 (control group), 1250, 2500 and 5000 mg/kg body weight. Mortalities, clinical findings, autopsy and body weight changes were monitored daily for the 14 days following the administration according to the Regulation of Korean Food and Drug Administration. Results : We observed survival rates, general toxicity, change of body weight, and autopsy. Single oral administration of YJT with different dosages, no animals died of the test drug. Autopsy of animal revealed no abnormal gross finding. Therefore, $LD_{50}$ value of YJT for ICR mice was more than 5000 mg/kg on oral route. Conclusions : These results suggest that no toxic dose level of YJT in mice is considered to be more than 5000 mg/kg. Consequently, it was concluded that YJT have no effect on acute toxicity and side effect in ICR mice.