본 연구는 한국형 포장설계법 과제의 일환으로 수행된 콘크리트슬래브의 건조수축특성에 대한 연구로서 형상비 및 굵은 골재의 종류를 달리해 현재까지 252일간 수행된 실험결과이다. 실제 포장용 콘크리트 슬래브의 형상비에 접근하기 위한 방안으로 시편 일부 면의 수분 증발을 막기 위해 일부 면에 3중 코팅 처리와 랩 처리를 하였다. 예비실험결과 본 실험에서 채택한 수분방지 코팅 처리가 3달 정도까지는 신뢰성이 있음을 알 수 있었다. 동일한 형상비에서 사암을 사용한 콘크리트 시편의 건조수축이 석회암인 경우보다 형상비에 따라 1.32~1.80배 크게 측정되었다. 측정된 건조수축 변형률을 기존의 ACI와 CEB-FIP의 건조수축 모델식과 비교한 결과 두 식 모두 과소평가됨이 확인되었다. 최종적으로 재령 및 형상비 등을 고려한 다중 비선형 회귀분석을 통해 본 실험에 적합한 콘크리트시편의 건조수축 모델식을 제시하였다.

To investigate the modifying effect of Kwao Kreu, Pueraria mirifica (PM), we performed two kind of studies which are the non-surgical medium-term carcinogenicity study and the modulation of gap functional intercellular communication study. The first study, a non-surgical medium-term carcinogenicity bioassay was done to investigate the modifying effect of Kwao Kent, Pueraria mirifica (PM), a rejuvenating folk medicine from Thailand, on the male F344 rat liver. Specific pathogen free, male 6-week-old F344 rats were divided into ten groups. To induce hepatocarcinogenesis, those in all groups were given a single i.p. injection of DEN (200 mg/kg) and were received two i.p. injection of DGA (300 mg/kg) at the ends of weeks 2 and 5. Rats of group 3-6 were given sodium phenobarbital (PB 0.05 % in drink). A diet containing 10 mg/kg PM was given to group 2 during the post-initiation phase and to groups 4 and 5 during promotion and initiation phase, respectively. Group 6 was given the experimental diet alone throughout the experiment (8 weeks). Rats of group 7, 8, 9 and 10 were fed 1000 mg/kg PM in the same manner as group 2, 4, 5 and 6. All animals were sacrificed at 8 weeks after DEN administration. Result of the iimmunohistochemical staining of the glutathione S-transferase placental form (GST-p) indicated that the numbers and areas of the preneoplastic leisions were not significantly changed in all PM treatment group comparing to control group. A.Iso the numbers and areas of GST-p positive foci among group 7, 8, 9 and 10 were not significantly changed in comparing to control group. To study the effect of PM on the modulation of gap functional intercellular communication, the present study was performed scrape-loading dye transfer (SL/DT) assay in human keratinocytes. The results showed that PM could not modulate GJIC. These results indicate that Pueraria mirifzca may have no carcinogenic effects on experimental hepatocarcinogenesis in rats and gap functional intercellular communication in human keratinocyte.

This study was carried out to evaluate the irritant potential of P-toothpaste in hamster cheek pouch. The test materials were applied once at the beginning of this study into right pouches of hamsters and maintained for 14 days. Animals were administered with P-toothpaste, Bamboo salt toothpaste, D.W. and control solution, respectively. In order to evaluate the irritant potential in mucosa of hamster cheek pouch, we observed clinical signs, mortality, body weights and gross and histopathological findings for 14 days. In all groups, there were neither dead animals nor significant changes of body weights. In addition, there were no differences between D.W. and Ptoothpaste treated group in gross and histopathological findings. Therefore, these results suggest that there was little irritant potential of P-toothpaste in hamster cheek pouch.