• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.783-786
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• 2000

In this paper, physical properties and dielectric characteristics of LLDPE and EVA which are used as a blending material to improve PE's performance are studied. LLDPE of 0.92[g/cm3] and EVA with the EVA contents of 12.5[%1 were selected as specimens, and X-ray diffraction(XRD) are used to analysis physical properties. We measured dielectric constant with the frequency range from 20[Hz] to 1 [MHz], applied voltage 6[V] and the temperature from 25[$^{\circ}C$] to 110[$^{\circ}C$]. From XRD, LLDPE has a crystallinity of 53[%] and, 46[%] for EVA. LLDPE has as low tan$\delta$ as of 10$^{-3}$ ~10$^{-4}$ and inflection point near 500[Hz]. At frequency region lower than 500[Hz], tan$\delta$ decreases with frequency and increases with temperature and it is considered to be caused by conductive carriers within specimen. Over 500[Hz], it is the reverse and we thought that it was caused by decrease of relaxation time due to Debye theory, EVA has tan$\delta$with the values of 10$^{-2}$ ~10$^{-3}$ , which is higher than that of LLDPE, and it has inflection point at 60[Hz]. It is shown that Dielectric characteristics of EVA are similar to LLDPE's.

• Clean Technology
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• v.20 no.3
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• pp.205-211
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• 2014

Biomass-based plastics containing the biomass content higher than 25 wt% have been considered as environment-friendly materials due to their effects on the reduction in the $CO_2$ emission and petroleum consumption as well as biodegradability after use. This article described the effect of the additions of oxo-biodegradable additive, 4 kinds of plant biomass, unsaturated fatty acid, citric acid in the properties of polyethylene films. Bio films were prepared using a variety of biomasses and tested for feasibility as a food packaging film. Mechanical properties such as tensile strength and percent elongation at break were evaluated. Husk biomasses from such as corn, soybean, rice, and wheat were pulverized using air classifying mill (ACM) and four different types of packaging films with thickness of $50{\mu}m$ were prepared using the pulverized biomass and low density polyethylene/linear low density polyethylene. The packaging film with wheat husk biomass was found to have greater mechanical properties of elongation and tensile strength than the other samples. Biodegradability of bio film was measured to be 51.5% compared to cellulose.

• Korean Chemical Engineering Research
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• v.45 no.4
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• pp.410-413
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• 2007

The effect of internal donor(ID) in the heterogeneous Ziegler-Natta catalyst on the ethylene-1-butene copolymerization and the molecular structure of the resulting copolymer was investigated. $SiO_2$-supported $TiCl_4$ catalysts having ID/Ti molar ratio of 0.5 were prepared with ethyaluminium dichloride, magnesium alkyl, 2-ethyl-1-hexanol and $TiCl_4$. Three different IDs were employed such as ethylbenzoate(EB), diisobuylphthalate(DIBP) and dioctylphthalate(DOP). ID-added catalyst showed a larger fraction of Ti(+3) compared to that of no ID-added catalyst. The EB-added catalyst showed the highest activity in copolymerization. Xylene soluble value decreased by more than 50 % with ID-added catalysts compared to that of no ID-added catalyst. Crystaf analysis showed the chemical compositional distribution of PE copolymer was improved in the case of DIBP-added catalyst significantly. It could be explained that the presence of ID could make more even active sites and block the non-stereospecific active sites.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.100-100
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• 2017

2016년부터 중국에 수출한 진공포장 쌀이 진공이 풀려 중국 현지 소비자들에게 품질에 대한 신뢰저하로 외면 받아 판매에 어려움을 겪었다. 진공풀림 원인은 주로 포장재의 모양, 과열 열접착 및 운송 중 부주의 등을 들 수가 있다. 따라서 본 연구에서는 쌀 진공포장 후 진공 풀림현상이 발생되는 원인을 분석하고, 진공포장에 적절한 포장재 및 취급조건에 대해 구명하여, 중국 쌀 수출 시 품질신뢰도 및 경쟁력 제고로 쌀 수출 확대를 위해 진공 포장재, 진공포장기술 및 운송 취급 방법을 제시하고자 하였다. 미곡종합처리장에서 사용하고 있는 플라스틱 필름 포장재의 적합 여부를 살펴보기 위하여 산소투과도 및 투습도를 산소투과도 측정장치(OX-Tran Model 2/61, Mocon, USA), 투습도 측정장치(Permatran-W Model 3/33, Mocon, USA)를 이용하여 측정하였다. 적정 열접착 온도를 구명하기 위하여 열접착 작업시간 간격 3, 5, 10초 3수준으로 하고 가열시간을 0.2초~2초까지 9수준으로 설정하여 포장필름을 열접착한 후 접착상태를 조사하였다. 진공 포장된 쌀을 골판지상자에 2차 포장하여 운송할 때 진공풀림 현상이 발생 여부를 조사하기 위해 가상 운송시험을 진동시험 장치를 이용하여 수직 및 수평으로 진동시험을 수행하였으며, 또한 취급조건에 따라 진공풀림을 조사하기 위하여 골판지 상자단위, 비닐포장 단위로 50, 70, 90cm 높이에서 낙하 시험을 하고 진공풀림여부를 조사하였다. 유통 중인 쌀 진공 포장재는 나이론(nylon)+선형저밀도폴리에틸렌(LLDPE) 복합필름으로 산소투과도가 $30{\sim}70cc/m^2{\cdot}day$, 투습도가 $2{\sim}4.5g/m^2{\cdot}day$로 산소투과도 및 투습도가 충분히 낮아 진공포장재로 적합했으며, 적정 열접착온도 조건은 $130{\sim}150^{\circ}C$에서 1~1.5초가량 가열해야 되는 것으로 조사되었다. 진동시험 및 낙하시험결과, 골판지박스 포장 시 완충재를 사이에 넣은 경우 진골풀림이 적었고, 상자단위나 비닐포장단위 모두 가능한 50cm보다 높은 곳에서 낙하충격을 받지 않도록 취급해야 할 것으로 판단되었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.283-290
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• 2020

In this study, a floater was developed for a frame-type solar power plant. The floater supports the frame and the solar panels. A finite element analysis was performed to design its shape and thickness, and the floater was manufactured by a rotational molding method using linear low-density polyethylene. It was found that the floater did not cause collapse and it maintained its stiffness even at 4 times the maximum load of 322.7 kgf. To perform a long-term compression test, a weight-type load application device that uses gravity was designed and manufactured. The amount of compressive deformation was measured for 7 days, and a long-term deformation equation was obtained. Even under small loads, continuous deformation was observed. However, the 10-year deformation amount for a constant load of 100 kgf was predicted to be small at about 4.64 mm. As a result, it was found that the developed floater could be used in a solar power plant on a body of water.