• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.5C
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• pp.193-198
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• 2012

Field and laboratory tests were performed to investigate the swelling(L value) and shrinkage modulus (C value) of soil and rock mixtures using 2 sites. According to test results, when disturbed soil and rock were mixed with same amount (5:5), the maximum density was achieved and showed 19% and 18% increased at each site comparing with the unit weight of rock only. Since measured L values of mixtures were overestimated about 4 to 11% compare to estimated values based on the conventional method. While C values were underestimated about 13~20% compare to conventional values due to the development of compacting equipments and effective construction management. When rock and soil were mixed in the ratio of 5 to 5, the unit weight of the mixture was higher than that of other mixtures and rock or soil only.

• Polymer(Korea)
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• v.32 no.4
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• pp.390-396
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• 2008

The hyaluronic acid (HA) polymers cross-linked with lactide (LA) using the crosslinking agent, 1,3-butadiene diepoxide (BD), were prepared in order to develop a biomedical material for tissue engineering. The degree of lactide and BD reaction of the crosslinked polymer was determined by the analysis of nuclear magnetic resonance spectroscopy. Both degree of reaction and swelling ratio increased with BD concentration or LA/HA mole ratio. Tensile modulus decreased with increasing BD concentration or decreasing LA/HA mole ratio. Degradation was shown to be progressed at two different stages and became slow with increasing BD concentration. It was shown that the first stage degradation was mainly due to the decomposition of ester linkage in the crosslinked structure. The cell growth inhibition increased with BD concentration. Although cytotoxicity was slightly observed in the high BD concentration, the value was very low (below 6%) enough not to affect the cell growth.