http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
결정연신법으로 연신한 고밀도 폴리에틸렌 배향물의 비선형 동적 점탄특성 발현 메커니즘
조남주,이상걸 釜山大學校生産技術硏究所 1997 生産技術硏究所論文集 Vol.53 No.-
결정연신법으로 연신한 고밀도 폴리에틸렌(HDPE) 배향물의 피로과정에서의 비선형 점탄특성을 비선형 점탄성 파라미터, NVP(Nonlinear Viscoelastic Parameter)로 평가하였다. NVP는 가해준 변형에 대한 응답 응력파의 기본 응력파(선형적 응답)로 부터의 차이를 직접 측정하여 이를 규격화한 것이다. 피로과정에서의 비선형 점탄특성의 발현은 HDPE 배향물의 피로강도에 지대한 영향을 미친다는 사실을 알 수 있었으며, NVP가 고분자재료의 내피로성을 평가하는 척도로서 사용 가능하다는 사실이 증명되었다. 또한, 피로과정에서의 고차구조 변화와 비선형 점탄특성과의 관계를 조사한 결과, 반복 변형이 HDPE 배향물의 무정형 영역 또는 미결정의 경계면에 집중하면 할수록 NVP 값은 커지고 비선형 점탄특성이 현저해 짐을 알았다. 한편, 주위온도가 HDPE 배향물의 피로과정에서의 비선형 점탄특성에 미치는 영향을 검토한 결과, α-₁결정완화영역인 323K에서는 반복 변형이 라멜라간의 무정형 영역뿐만 아니라 mosaic block간에도 인가되어 NVP 값이 실온보다 감소하였으며, crack의 성장원이 되는 mosaic block간에 반복 변형이 가해지므로 피로강도는 실온보다 감소하였다. 또, α-₂결정완화영역인 350K에서는 라멜라 결정이 점탄성적인 거동을 하므로 무정형 영역 및 결정 영역이 함께 변형을 받게 되어 NVP 값은 실온보다 감소하였으며, 피로강도는 반복 변형이 비교적 균일하게 가해지므로 α-₁결정완화영역에서보다 증가하였다. Nonlinear dynamic viscoelasticity under cyclic fatigue for the oriented high-density polyethylene(HDPE) drawing at α₂-crystalline relaxation temperature was discussed in terms of nonlinear viscoelastic parameter(NVP) defined as the contribution of higher harmonics of Fourier expanded stress signal. It was clarified that the appearance of nonlinear viscoelasticity remarkably reduced the fatigue strength of the oriented HDPE. And also, it was confirmed that NVP could be used as an index of fatigue lifetime or fatigue strength for polymeric solids. Also, it could be concluded from the results of higher-order structural change during fatigue process that nonlinear dynamic viscoelasticity of the oriented HDPE originated from the deformation of the amorphous and/or crystallite boundary regions rather than that in the crystalline phase itself. In the case of a cyclic fatigue test at the α₁-crystalline relaxation temperature, since the degree of cyclic strain concentration in the amorphous region decreased because of the deformation in the intermosaic block region, the magnitude of NVP became smaller than that at room temperature. Also, the fatigue strength was lower than those at the other ambient temperatures, because lamellar crystals were decomposed into small mosaic block crystals whose interfaces became the origin of crack growth under cyclic straining. In the case of a cyclic fatigue test at the α₂-crystalline relaxation temperature, because of a more homogeneous sample deformation and the decrease of cyclic strain concentration in the amorphous and/or crystallite boundary regions, the magnitude of NVP became smaller than that at room temperature. The fatigue strength was greater than that at the α₁-crystalline relaxation temperature due to the more homogeneous sample deformation.
일본의 기초지자체 산림지역의 위치 분석과 활성화에 대하여 –후쿠오카 찌꾸고가와 (福岡県筑後川)의 산림지역을 사례–
이상걸,조태동 한국환경과학회 2024 한국환경과학회지 Vol.33 No.1
This study attempted to derive regional characteristics from forest areas in Fukuoka Prefecture, which are traditional forestry areas in Japan, but have reached a time when new conversions are needed due to a decrease in wood prices and loss of motivation due to natural disasters such as typhoons. As a result, most of them are distributed to areas that include urbanization, rural areas, and mountain villages, and production areas of remote materials, which have the potential for forestry, but need to change policies to revitalize them due to low mountain utilization. Therefore, forest management and forestry production activities by multiple municipalities were judged to be efficient in these regions due to the promotion of forestry infrastructure, such as the expansion of forestry networks and the creation of mechanized forestry.
녹지환경을 고려한 탄소흡수원의 기초정보에 대하여 -강릉지역의 지정학적 위치를 중심으로-
이상걸,조태동 한국환경과학회 2023 한국환경과학회지 Vol.32 No.9
The study analyzes the forest status of each local government for Korean forests and believes that it can be used as basic data for setting the direction pursued by each local government. The study took into account the fact that the forest rate in Korea was 63.5%, because it was judged that the higher the proportion of forest area, the more important it was to use the characteristics of forests. The characteristics of forests were analyzed based on four factors in 12 factors to identify the location of the ground body by dividing seven types. In addition, basic information on carbon absorption sources was provided by grasping the ability of carbon absorption sources per year through the amount of forest resources to be analyzed. In addition, as a result of analyzing the characteristics of the weather for the promotion of carbon absorption sources, the flat area on the side of Gangneung Mountain was a warm forest with a warm index of 106.0.