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인산 칼슘을 사용한 수산화아파타이트 시멘트의 응결·경화 특성에 관한 연구
김한엽,박찬근,송태웅 경남대학교 신소재연구소 1996 論文集 Vol.6 No.-
습식법이나 수열법으로 합성한 hydroxyapatite(HAp)의 분말을 성형, 열처리한 소결체는 지금까지 알려진 바이오 세라믹스 중 생체친화성이 가장 우수한 것으로 입증되고 있으나 소결에 따르는 제조상의 몇가지 문제점을 안고 있다. 본 연구에서는 소결에 의하지 않고 tetracalcium phosphate(TTCP)분말과 dicalcium phosphate dihydrate(DCPD) 분말의 혼합물로 만든 paste를 용해·침전반응으로 응결·경화시켜 직접 HAp 경화체를 얻고, 이때 몇가지 변수가 HAp의 생성과 응결 및 경화특성에 미치는 영향을 검토하였다. TTCP와 DCPD로 조합한 시멘트의 수화반응생성물은 HAp 경화체였으며 이의 미소결정의 interlocking에 의해 응결·경화 하였다. 반응온도 및 HAp 종자의 첨가는 주로 초기단계의 반응속도에 영향을 주었다. 50℃에서의 HAp 생성 반응은 24시간 이내에 거의 완료되었다. Hydroxyapatite ceramics, one of the excellent biocompatible materials, are usually prepared by sintering of hydroxyapatite powders from wet chemical methods. But some problems caused by sintering process are still remained. In this study, instead of powder sintering methods. hardened bodies of hydroxyapatite were prepared by self-hardening reaction of cement paste composed of powdered tetracalcium phosphate(TTCP) and dicalcium phosphate dihydrate(DCPD). Some effects of seeding, reaction temperature on setting and hardening properties were investigated . The hydration products of the hardened paste were composed of finely-crystallized hydroxyapatite which causes setting and hardening by interlocking themselves. Self setting and hardening reaction are accelerated by elevating reaction temperature and addition of hydroxyapatite powders as a seeding materials. The hydration reaction of the paste. at 50C. was nearly finished within 24 hours after mixing with water.
Synthesis and Properties of Self-hardening Calcium Phosphate Cemetns for Biological Application
Song, Tae-Woong,Kim, Han-Yeop The Korean Ceramic Society 1997 The Korean journal of ceramics Vol.3 No.2
Fine powder of $\alpha$-tricalcium phosphate, tetracalcium phosphate and dicalcium phosphate were mixed together to prepare self-setting cements which form hydroxyapatite, one of the well-known biocompatible materials, as the end of products of hydration. Hardening behaviour of the cements was examined at the temperature range of 37~$70^{\circ}C$ and 150~$250^{\circ}C$ under the normal and hydrothermal condition respectively. The conversion of cements into hydroxyapatite was significantly improved ast elevated temperature and the paste was strengtheed by interlocking of hydroxyapatite crystals, indicating that the strength is determined by microtexture rather the amount of conversion of cements into hydroxyapatite.
아스팔트 도로포장의 균열률에 대한 지역별 기대수명 추정
송현엽(Song, Hyun Yeop),최승현(Choi, Seung Hyun),한대석(Han, Dae Seok),도명식(Do, Myung Sik) 대한토목학회 2021 대한토목학회논문집 Vol.41 No.4
사회기반시설의 장래유지 관리비용 추정은 불확실한 미래를 다루기 때문에 신뢰성 높은 파손예측모델의 구축이 매우 중요하다. 하지만, 지자체에서는 예산, 인력, 파손예측모델의 필요성 등에 대한 인식부족으로 인해 기반시설의 정확한 파손예측모델 개발이 어려운 실정이다. 따라서 본 연구에서는 베이지안 마르코프 혼합해저드 모델을 활용하여 일반국도 아스팔트 도로포장의 균열률에 대한 지역별 기대수명을 추정하였다. 또한 정확한 기대수명 추정을 위하여 교통량, 축하중, 포장강도, 기후, 제설제사용량 등의 환경변수를 적용하여 추정결과에 대한 신뢰성을 확보하고자 하였다. 분석결과, 지역별로 최소 13.09년에서 최대 19.61년의 기대수명이 추정되었다. 본 연구결과를 활용할 경우, 지역적 파손특성이 고려된 신뢰성 높은 장래 유지관리비용의 추정이 가능할 것으로 기대된다. Since future maintenance cost estimation of infrastructure involves uncertainty, it is important to make use of a failure prediction model. However, it is difficult for local governments to develop accurate failure prediction models applicable to infrastructure due to a lack of budget and expertise. Therefore, this study estimated the life expectancy of asphalt road pavement of national highways using the Bayesian Markov Mixture Hazard model. In addition, in order to accurately estimate life expectancy, environmental variables such as traffic volume, ESAL (Equivalent Single Axle Loads), SNP (Structural Number of Pavement), meteorological conditions, and de-icing material usage were applied to retain reliability of the estimation results. As a result, life expectancy was estimated from at least 13.09 to 19.61 years by region. By using this approach, it is expected that it will be possible to estimate future maintenance cost considering local failure characteristics.
생분해성 PLA-PBAT 블렌드 필름을 이용한 친환경 포트의 특성 연구
박한샘 ( Han Saem Park ),강재련 ( Jae Ryeon Kang ),송강엽 ( Kang Yeop Song ),서원준 ( Wonjun Seo ),이선주 ( Seonju Lee ),이원기 ( Won Ki Lee ) 한국환경과학회 2015 한국환경과학회지 Vol.24 No.8
Since single-use disposable plastic usage has steadily been increasing, recent trends in polymeric research point to increasing demand for eco-friend materials which reduce plastic waste. A huge amount of non-degradable polypropylene (PP)-based pots for seedling culture are discarded for transplantation. The purpose of this study is to investigate an eco-friendly biodegradable material as a possible substitute for PP pot. The blend of poly(lactic acid) (PLA) with poly(butylene adipate-co-terephthalate) (PBAT) was used because of its good mechanical and flexible properties as well as biodegradation. After landfill, various properties of the blend pot were investigated by UTM, SEM, NMR and TGA. The results showed the tensile strength of the blend film rapidly decreased after 5 weeks of landfill due to degradation. From NMR data after landfill, the composition of PLA in the blend was decreased. These results indicate that the biodegradation of the blend preferentially occurs in PLA component. To investigate the effect of holes in pot bottom and side on root growth, a plant in the pot was grown. Some roots came out through holes as landfill period increases. These results indicate that the eco-friendly pot can be directly planted without the removal of pot.