• Elastomers and Composites
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• 제45권3호
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• pp.170-187
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• 2010

열가소성 탄성체(thermoplastic elastomer, TPE)는 학술적 기초 및 응용은 물론이고 산업적, 상업적으로 매우 중요한 유기 소재의 하나이다. TPE는 블록 공중합체뿐만 아니라 많은 다른 고분자분야에서도 중요한 한 영역으로 생각할 수 있다. 가황 고무가 갖고 있는 성질과 열가소성 플라스틱이 보이는 성질을 동시에 갖고 있기 때문이다. 또한 블록과 그라프트 공중합체, 이들 혼합물, 가황 물질에서 비롯된 일련의 성질을 보여주기 때문이다. 이 소재의 중요성은 출판되는 간행물(논문, 특허, 보고서 등)의 수에서도 알 수 있다. 'thermoplastic elastomer'를 키워드로, 열가소성 탄성체의 개념이 들어간 간행물의 숫자를 SciFinderScholar를 이용하여 조사한 결과, 1939년 ~ 2010년 7월 10일 사이에 18,508편에 이르렀으며, 특히 1990년 중반부터 그 숫자가 기하급수적으로 늘었다. 열가소성 플라스틱의 성질과 가교탄성체의 성질을 동시에 갖고 있는 TPE의 영역을 설명할 때 과학적, 기술적, 상업적인 관점을 모두 고려해야 한다. 본 보문에서는 TPE의 역사적인 관점을 먼저 설명하고, 화학적, 구조적 및 모폴러지 연구 동향을 다루고자 한다. 또한 주요 제조법과 현대적 분석 기술을 다룰 것이다. 이어 TPE의 성질과 가공성, 유기소재 사이에서의 입지와 응용에 대해도 분석한 후, 향후의 발전 방향에 대하여 논의하고자 한다.

• Korean Chemical Engineering Research
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• 제49권1호
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• pp.47-55
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• 2011

K사의 고무 사출성형에 있어서 애로사항인 등속조인트 부트(boots)의 크 (crack) 발생 등의 문제점을 해결하기 위하여, 상용 CAE 프로그램인 MOLDFLOW(Ver. 5.2)를 이용한 전산모사를 수행하여 적정금형설계를 도출하고 적정작업조건을 구축하였다. 그 결과 크 의 발생 원인은 크 이 발생하는 위치에 형성되는 weld 및 meld line의 형성 때문이고, 또한 크 이 발생하는 위치에서의 가류(curing)가 불완전한 것이 확인되었다. 이와 같은 weld 및 meld line의 형성을 방지하기 위해서 게이트(gate)의 위치를 변경하고 최적위치에 설계함으로써, 유동선단(melt front)의 충돌 또는 수지흐름의 만남을 최소화하는 충전패턴(fill pattern)을 형성하고 부트 안쪽 하단의 크 발생을 방지하였다. Weld 및 meld line과 에어트랩(air trap) 불량이 가장 큰 게이트 위치는 각각 최적 게이트위치를 기준으로 서로 정반대 방향임이 관찰 되었다. 한편 몰드(mold)의 온도를 $170^{\circ}C$로 유지하게 함으로써 크 이 발생했던 위치에 가류조건을 만족시켰다.

• 수산해양기술연구
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• 제15권2호
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• pp.83-94
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• 1979

權現網漁具의 網形에 관하여는 李등이 1971년에 在來式에 관하여, 1978년에 日本式 파치網에 관하여 模型實驗을 실시하여 보고한 바 있으나, 이번에 이들 漁具의 場点을 살리면서 短點을 보안한 試驗漁具改式良 79型을 재작하여, 1979년 5월부터 10월까지 6개월간. 멸치漁場이 형성되는 廈南一圓에서 試驗操業을 실시하여 그 漁具의 性能을 검토하고, 漁獲性能을 비교한 바, 그 性能이 在來式보다 우수하다는 것이 규명되었다

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.471-474
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• 2007

Eucalyptus plantations play a major role in the China's ecological, social, economic and other aspects and presently China is the second largest producer of Eucalyptus in the world next to Brazil. It was introduced as an ornamental tree during 1890 but later it became a commercial crop. During 1960s large number of Eucalyptus timber were used for railway sleepers and it was also used as shelter belt for rubber trees. It becomes one of the important national resources of commercial timber once the production reached to 5 million $m^{3}/yr$. Through Eucalyptus oil, it brought about 20% of foreign exchange. In the present study, it was aimed to estimate the Eucalyptus growing area in the southern Guangdong in China in terms of aerial extent and changes between 1991 and 2001 using Landsat TM and ETM+ data. Object based classification technique and subsequent temporal change detection analysis were followed to identify the changes between the periods. In the present study, the total area was divided into three classes viz., plantation area with trees, plantation area without trees and others. Object oriented classification was found to be more accurate in the present study. Overall increase of about 23.62 $km^{2}$ was noted between 1991 and 2001 in the plantation area. With reference to the present study area, the growth of Eucalyptus growing area was 7.4% in the 10 year periods. From this study it is clear that the area under Eucalyptus cultivation is growing considerably year by year in China. However, elaborate study must be conducted considering larger areas to accurately predict the growth of Eucalyptus growing areas.

• Elastomers and Composites
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• 제15권1호
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• pp.3-9
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• 1980

일정온도와 압력에서 상업용 고분자필름들의 산소투과도와 산소투과방지도에 관하여 연주하였다. 산소투과방지 도는 산소특과도의 역수로 정의하고 coulometric oxygen permeability tester를 사용하여 $23{\pm}1^{\circ}C$, latm에서 24시간 동안 투과한 산소의 량을 측정하였다. 산소투과방지도의 상대적 크기는 다음과 같은 순서로 감소함을 밝혔다. 연신 Nylon (O. Nylon)> 연신 Polyester (O. PET)> 무연신 Nylon (N. Nylon)> 무연신 Polyester(N. PET)> 경질 Polyvinyl chloride (Rigid PVC)> 반경질 Polyvinyl chloride (Semirigid PVC)> 연신 Polypropylene (O. PP)> 연질 Polyvinyl chloride (P. PVC)> 무연신 Polypropylene (C. PP)> 저밀도 Polyethylene(LDPE)> 고밀도 Polyethylene (HDPE, Inflation)> 고밀도 Polyethylene (HDPE, T-die) 필름들의 산소투과방지도는 고분자의 극성, 필름의 두께 및 기계적 연신성의 증가에 따라서 증가하고 PVC에서는 가소제 첨가에 따라서 감소하였다. 포장재료로서 고분자 필름은 고분자 주쇄에 극성이 있는 필름과 극성이 없는 필름들을 산소 및 습기투과방지를 위하여 첩합하여야 한다.

• Journal of Animal Science and Technology
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• 제65권4호
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• pp.878-889
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• 2023

Animal welfare during transport became an largely issue because of increasing demand for improved animal welfare standards. Most studies on the animal welfare during transportation have concentrated on the atmosphere and the temperature of the truck compartments. Thus, the objective of study was to collect and quantify three axis acceleration and determine the effect of bedding for transporting pigs from farm to slaughterhouse. A total of 2,840 crossbred fattening pigs with a live weight of approximately 115 kg were used. They were raised in the same commercial farms and transported to the same commercial slaughterhouse. A 3×2×2 completely randomized factorial design was used to investigate effects of rubber type bedding (bedding or non-bedding) and two levels of driving style (aggressive or normal) in three different time periods with different outside temperatures. Air temperature treatments were as follow: high temperature ([HT] higher than 24℃); low temperature ([LT] lower than 10℃); normal temperature ([NT] 10℃ to 24℃). In our experiment, pigs transported under aggressive driving style showed lower (p < 0.05) pH and water holding capacity (WHC) than those transported under normal driving style. Pigs transported under normal driving style showed a lower percentage of drip loss (DL) (p < 0.05) than those transported with an aggressive driving style. Also, transported with bedding showed higher (p < 0.05) lying behavior but lower (p < 0.05) sitting behavior than those transported without bedding. Pigs transported under normal driving style showed lower (p < 0.05) cortisol level than those transported under aggressive driving style. In conclusion, aggressive driving style cause acute stress in pigs, while bedding helps alleviate acute stress in pigs during transportation in LT.

• 한국정밀공학회지
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• 제29권10호
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• pp.1056-1061
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• 2012

FEM analysis is essential to shorten the development time and reduce the cost for developing high-performance machine tools. Mount joint parts play important role to ensure static and dynamic stability of machine tools. This paper suggests a computational modeling of mount joint part of machine tools. MATRIX27 element of ANSYS is adopted to model mount joint parts. MATRIX27 allows the definition of stiffness and damping matrices in matrix form. The matrix is assumed to relate two nodes, each with six degrees of freedom per node. Stiffness and damping values of commercial mount products are measured to build a database for FEM analysis. Jack mounts with rubber pad are exemplified in this paper. The database extracted from the experiments is also used to estimate of stiffness and damping of untested mounts. FEM analysis of machine tools system with the suggested mount computational model is performed. Static and dynamic results prove the feasibility of the suggested mount model.

• 한국소음진동공학회논문집
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• 제18권4호
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• pp.465-472
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• 2008

An automotive windshield wiper system is modeled mainly for vibration analysis purpose. The model is composed of solid links, ideal joints, imperfect joints to simulate unavoidable manufacturing defects and bushings having stiffness, contact between a wiper blade and a wind screen glass, friction, a spring and an actuator. Main stream of wiper dynamics analysis has been obtaining a closed form of system of equations using Newton's or Lagrange's formula and doing a numerical simulation study to understand and predict the behavior of it. However, the modeling process is complex since a wiper system is of multibody and a contact problem occurs. When imperfection, such as dead zone of a joint and stiffness of a rubber bushing, should be included, the added complexity makes the modeling difficult. Since the imperfection is understood as main cause of problematic vibration, the dynamics model of a wiper system aiming vibration analysis should include such unavoidable manufacturing defects in the model. An open form of dynamic model of a automotive windshield wiper system with imperfect joints using a commercial software is obtained and a simulation analyssis is conducted for vibration reduction study.

• 공업화학
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• 제3권2호
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• pp.201-206
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• 1992

Annual amount of plastics waste including rubber and leather waste, generated in 1990 was about 2,600,000 tons. Amount of generation of plastics waste has rapidly increased, but fractions of recycling and incineration have gradually decreased. Recently, two-stage incinerator, consisting of gasifier and gas combustor, draws much attention in Korea. Plastics are gasified in the starved air condition in the gasifier and produced gas is fired in the combustor. Combustion of produced gas is much easier than that of solid plastics, and produces a little pollutants. Standardzation of technology and process automation are still needed, but this incineration technology is in the commercial stage. Next topic concerned with this two-stage incineration will be how to treat complex plastics waste including toxic substances generated from automobiles and household appliances. Pyrolysis, realized by indirect heating in inert atmosphere, can provide high-quality products with minimum emissions. Many plastics are easily decomposed into oil in pyrolysis conditions, which can be utilized as chemical feedstocks, or gasoline or kerosene depending on feed materials and operating conditions. This has been demonstrated in several pilot-scale tests performed in Japan, Germany, etc. Easy removal of HCl from PVC is one of the most decisive merits of pyrolysis process. But in general, further efforts should be made for the process to obtain marketability. The future of pyrolysis process depends on public concern about environmental problems and oil prices.

• Elastomers and Composites
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• 제54권4호
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• pp.294-298
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• 2019

A three-layered PVC sheet consisting of polyvinyl chloride (PVC) and woven polyester fabric was prepared by extrusion and calendering. The flexibility and durability of the PVC were tuned by adding plasticizers, additives, and surface coatings. The tensile and tear strengths of the three-layered PVC sheet were higher than those of commercial two-layered sheet, while exhibiting low weight. The concentrations of the total volatile organic compounds (TVOCs) and formaldehyde (HCHO) emitted from the sheet were also lowered. The PVC sheet remained stable after prolonged exposure to UV light, signifying that the PVC sheet is suitable for cargo screen applications.