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플라스틱 골재 종류와 양생 방법에 따른 시멘트 복합체의 물리적 특성에 관한 실험적 연구
천현욱 ( Cheon¸ Hyeon-uk ),권준희 ( Kwon¸ Jun-hee ),이우진 ( Lee¸ Woo-jin ),정의영 ( Jeong¸ Ui-yeong ),김우석 ( Kim¸ Woo-suk ) 한국복합신소재구조학회 2021 복합신소재구조학회논문집 Vol.12 No.5
최근 대규모 토목 및 건축 구조물 증가 추세로 건설 부재의 고강도 및 경량화에 대한 수요가 높아지고 있다. 기존 시멘트 경량 복합체의 경우 단위 체적 중량이 낮아 강도 저하 문제가 발생할 수 있다. 보통 경량화를 위해서 시멘트 복합체를 배합할 때 일반 경량골재와 고무재질의 경량골재, 플라스틱 펠릿 등 다양한 인공 경량골재를 적용한 시멘트 복합체로 경량화를 확보할 수 있다. 이 중에서도 시멘트 복합체의 인공 경량골재로 플라스틱을 사용하면 상대적으로 골재 자체의 강도를 확보하면서 경량화를 꾀할 수 있지만 재료의 매끄러운 표면 특성으로 인해 시멘트 페이스트와 부착하는 데 불리한 부분이 있고 이는 콘크리트 골재 또는 시멘트 복합체 골재로서의 사용에 있어 단점이 된다. 띠라서 이번 연구에서는 기존 연구에서 플라스틱 골재로 가장 적합한 유형으로 확인된 PP, PE 두가지 유형의 플라스틱 골재와 강섬유, 양생방법을 변수로 하여 실험을 진행하였고 실험 결과 플라스틱의 비중이나 표면 재질뿐만 아니라 강섬유의 혼입유무, 양생방법에 의해서 시멘트 복합체의 물리적 특성이 변화된다는 것을 확인하였다. Recently, large-scale civil and architectural construction has increased the demand for high-strength and lightweight structures. In the case of the lightweight cement composite, the unit volume weight may be reduced; however, a decrease in strength occurs. In general, when mixing cement composites for weight reduction, it is possible to cut down weight by combining cement composites using artificial aggregates, such as general lightweight aggregates, rubber lightweight aggregates, and plastic pellets. Furthermore, the aggregate strength can be secured if plastic is used as a lightweight artificial aggregate for cement composites. Still, due to the material’s surface properties, mixing with cement paste and using it as an aggregate is disadvantageous. Therefore, this study conducted experiments to select the most suitable plastic as an aggregate using steel fiber, curing method, and two types (PP and PE) of plastic cement composites as variables. The results showed changes in the physical properties of the cement composite according to whether or not the steel fiber is mixed, the curing method, and the specific gravity of plastic or surface material.
남은우(Eun Woo Nam),정헌화(Hun Hwa Jung),권준희(Jun Hee Kwon),이정희(Jung Hee Lee) 한국보건복지학회 1998 보건과 복지 Vol.1 No.-
This study was conducted by analyzing the medical records of 784 people, and the questio nnaires of 414 people who participated in the free medical service at Pusan station from July 22, 1998 to August 12 , 1998. The purpose of this study was to investigate the results of free medical service for the homeless and jobless performed by the civic organization and to pr ovide the government and non Government Organizations with informations which are necessary in order to have cooperation among these organizations.<br/> The major results were as follows'<br/> 1. In case of the people who were consulted by the physician, the major diseases were the digestive disease(22.3%), influenza(12.8%), arthritis(10.7%), and urinary ruseases(8.5%) Among them 10 % needed an accurate diagnosis by a specialist.<br/> 2. Among respondents, 84.1% were male, 37.2% were over 61 years old, and 52.9% were not in good health conrution.<br/> 3. 85.5% didn't have a job, 58.2% were in poor health but didn't visit to the medical center in more than six months, even though they didn't have good health condition.<br/> 4. 80.0% responded that the government and social organizations should provide an unemployed worker with the opportunities to get a job. And, 96.6% appreciated this free of medical service program.<br/> 5. The respondents who divorced, living separately, or widowed were not in good health compared to the respondents living with husband or wife.