To control degradation rate of biodegradable poly(lactide)s (PLA), the stereochemical PLAs with different ratios of d-lactide and l-lactide units were synthesized by the ring open polymerization and the their degradation kinetics were measured by a Langmuir film balance. The alkaline (pH=11) degradation of poly(l-lactide) (l-PLA) monolayer showed the faster rate at a surface pressure of 4 mN/m in the ranges from to 0 to 7 mN/m. However, the enzymatic degradation of l-PLA with Proteinase K did not occur until 4 mN/m. Above a constant surface pressure of 4 mN/m, the degradation rate was increased with a constant surface pressure. These behaviors might be attributed to the difference in the contacted area with degradation medium: alkaline ions need small contact area with l-PLA while enzymes require much bigger one to be activated due to different medium sizes. The stereochmical PLA monolayers showed that the alkaline degradation was increased with their optical impurities while the enzymatic one was inversed. These results could be explained by the decrease of crystallinity with the optical impurity and the inactivity of enzyme to d-LA unit.

연구에서는 Sprayed FRP 공법을 이용하여 보강된 철근 콘크리트 전단 파괴형 기둥의 구조성능을 평가하기 위하여 2/3 크기로 축소된 총 6개의 기둥 실험체를 제작하여, 일정한 축하중 (0.1Agfc')하에서 반복 횡하중을 가력한 구조 실험을 수행하였다. 4개의 실험체는 유리 및 탄소 단섬유와 에폭시 및 비닐에스테르 수지를 조합하여 Sprayed FRP로 보강하였으며, 또한 비교 목적을 위하여 고강도 탄소섬유시트(CFS)로 보강된 실험체 1개와 무 보강 실험체 1개를 포함하였다. 실험결과, Sprayed FRP로 보강된 실험체의 최대내력은 무 보강 실험체 대비 10～30%가 증가 하였을 뿐만 아니라, 연성은 약 1.15배 향상되어, 본 연구에서 제안한 Sprayed FRP 공법은 충분한 보강효과가 기대되는 신기술 이라고 판단된다.

두 양이온 유기폴리머(Hexadecyltrimethylammonium (HDTMA)과 Cetylpyridinium (CP))를 합성한 유기벤토나이트에 대해 음이온의 흡착특성을 조사하였다. 이들 유기벤토나이트는 상온에서 저면간격이 약 42.0 a으로 현저한 층간팽창을 나타냈다 유기벤토나이트 시료 0.2 g을 음이온인 질산염, 황산염, 인산염의 각 여러 농도별 용액 40 mL와 반응시킨 흡착실험을 행하였다. 그 결과, 무처리 벤토나이트는 모든 음이온에 대해서 거의 흡착능력을 보이지 않는데 비하여. 유기벤토나이트는 아주 높은 흡착성을 나타냈다. HDTMA-bentonite의 경우, 인산이온과 질산이온의 흡착률이 100 mg/L의 농도에서 약 90% 정도로 높게 나타나고, CP-bentonite의 경우, 질산이온의 흡착률이 100 mg/L의 농도에서 97%로 높게 나타났다. 음이온 및 유기벤토나이트의 종류에 따라 흡착거동이 약간차이를 나타냈다. 두 유기벤토나이트에 있어서 질산이온과 인산이온의 흡착률은 황산이온에 비해 모두 상대적으로 높게 나타났다. 이러한 유기벤토나이트의 높은 음이은 흡착성은 유해성 음이온의 제거와 같은 환경오염처리에 활용될 수 있을 것으로 생각된다.

An experimental study on the preparation of monolithic porous polymers by environmentally friend process in supercritical carbon dioxide has been carried out. Polymerization mixture composed of a cross-linking monomer, initiator and functional co-polymer was charged in the reactor with sapphire window. After the system was purged with a flow of CO2 for 15 min, the reactor was pressurized with liquid CO2 up to 100 bars. The reactor was isolated from and placed back to the system via quick connector for shaking until the mixture had become fully homogeneous. The reactor was then heated and pressurized to the required reaction conditions and left overnight. After cooling and CO2 evacuation, the polymer was removed from the reactor as dry, white, continuous monoliths. The effect of experimental conditions on the physical properties of porous polymer was systematically examined, and it was found that monomer content had a major effect on the physical properties of the polymers.

These experiments were conducted to investigate water uptake, electrical conductivity, germination percentage, seedling growth, and seedling establishment rate in direct seeding cultivation of rice. The rice seeds of six japonica type varieties were coated with 12 kinds of polymers in a standard concentration of 0.2% using seed coating machine. The water absorption of the polymer-coated seeds under saturation conditions was not different among varieties, and was the highest in kulcel, maltrin, and waterlock on the polymer-coated seeds. The electrical conductivity with waterlock (55.0 ~mu scm-1g-1 ) was higher than the control plot (45.6 ~mu scm-1g-1 ) and other treatments. The germination of the polymer-coated seeds was 95.9% at control plot, 92.7% at low temperature and 35.7% at high temperature. The total dry weight of seed decreased in the order of low temperature, control plot, and high temperature, and was effective in pvp (polyvinyl pyrrolidone), opadry, and sacrust. The seedling establishment rate in direct seeding cultivation ranged from 74.9 to 81.0% in flooded paddy surface, and ranged from 64.7 to 76.6% in dry paddy. In both cases, it decreased in the order of early, medium and medium-late varieties, but was enhanced in daran 8600, sepirect, and sacrust. According to this study the recommended polymers for direct seeding cultivation of rice are daran 8600, sepirect, and sacrust

Organics matters including algae are the major contaminants of Nak-dong river and it`s concentration is more increasing now. The use of coagulants has been incresed for the effective treatment of drinking water, and aluminum coagulants have been the most widely used in raw water treatment. However, when inorganic metal coagulant is excessively used for long period, it would result in secondary problems, such as increasing sludge production, enhancing the cost of water treatment process, and increasing concentration of residual metal, especially aluminum. Therefore, recently, in order to reduce the use of metal coagulant and enhance the coagulation effectiveness, several alternative coagulants, such as polymeric inorganic coagulants and organic polymers, have been used in water treatment plants. The objectives of this research were (1) to determine optimum dosage concentration and compare the coagulation efficiency at various pH ranges with alum alone, alum+cationic polymer, and alum+anionic polymer, (2) to evaluate the amount of alum reduced by using organic polymer, (3) to maximize removal efficiency of organic matter and minimize the concentration of residual aluminum.