• Journal of Biosystems Engineering
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• 제15권1호
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• pp.14-22
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• 1990

For efficient use of solar energy in plastic greenhouse, thermal storage system was developed. The system was constructed with the counter-flow type air-water heat exchanger using a thin polyethylene film as a medium of heat exchange parts. Experiments were carried out to investigate the heat exchange rate, optimum water flow rate, overall heat transfer coefficient, and the effectiveness of the counter-flow type air-water heat exchanger with polyethylene film bags. Mathematical model to predict air temperature leaving heat exchanger was developed. The results obtained in the present study are summarized as follows. 1. Heat exchange rate in the counter-flow type air-water heat exchanger with polyethylene film bags was compared to that of polyethylene film. Heat exchange rate was almost identical at air velocity of 0.5m/s on polyethylene film surface. But, heat exchange rate of heat exchanger with polyethylene film bag was $32{\sim}55KJ/m^2$ hr higher than that of polyethylene film at air velocity of 1.0m/s. 2. Considering the formation of uniform water film and the sufficient heat exchange rate of polyethylene film bags, optimum water flow rate in polyethylene film bags was $3.0{\sim}6.0{\ell}/m^2$ min. 3. The overall heat transfer coefficient of polyethylene film bags was found to be $35.0{\sim}130.0KJ/m^2\;hr\;^{\circ}C$ corresponding to the air velocity ranging 0.5 to 4.0 m/s on polyethylene film surface. And the overall heat transfer coefficient showed almost linearly increasing tendency to the variation of air velocity. 4. Mathematical model to predict air temperature leaving the heat exchanger was developed, resulting in a good agreement between the experimental and predicted values. But, the experimental results were a little lower than predicted. 5. Effectiveness of heat exchanger for the experiment was found to be 0.40~0.81 corresponding to the number of transfer units due to the variation of air velocity ranging 0.6 to 1.7 m/s.

• 한국잡초학회지
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• 제5권1호
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• pp.19-23
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• 1985

1. 화간(畫間) 지온(地溫)은 나지(裸地), 투명(透明) 및 청색(靑色)필름에서 높은 반면, 흑색(黑色) 및 녹색(綠色)필름과 짚으로 멀칭한 경우에 낮으며 투광율(透光率)도 흑색(黑色)필름과 짚으로 멀칭하였을 때 매우 낮았다. 2. 바랭이, 쇠비름, 망초를 제외한 대부분의 잡초는 투명(透明)필름에서 발아(發芽)가 양호(良好)하였으나 흑색(黑色)필름에서는 불량(不良)하였다. 청색(靑色)필름에서 쇠비름, 강아지풀과 털비름의 발아(發芽)가 촉진(促進)된 반면, 망초, 메귀리, 명아주, 바랭이, 망초를 비롯한 대부분의 잡초(雜草)는 녹색(綠色) 필름에서 발아(發芽)가 억제(抑制)되었다. 3. 잡초발생본수(雜草發生本數)는 투명(透明)필름에서 가장 많았고, 나지(裸地)에서도 비교적 많이 발생(發生)되었으나 녹색(綠色) 및 청색(靑色)필름, 짚멀칭에서는 매우 적었으며 흑색(黑色)필름에서는 잡초(雜草)가 거의 발생(發生)되지 않았다. 4. 잡초(雜草)의 건물중(乾物中)은 투명(透明)필름과 나지(裸地)에서 매우 높은 반면, 녹색(綠色) 및 청색(靑色)필름, 짚멀칭에서는 현저하에 감소(減少)되었으며 흑색(黑色)필름에서는 잡초(雜草)의 생장(生長)이 완전히 억제(抑制)되었다.

• 대한화학회지
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• 제7권1호
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• pp.58-64
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• 1963

Authors propose a new technique using polyethylene film instead of sodium chloride window as a cell material. Nujol mulls, liquids and aqueous solutions are sandwitched between two pieces of polyethylene film which are held between cardboards. Ordinary lead or stainless steel spacers could be used if exact cell thickness is desired. A more elaborate cell can be assembled by injecting samples between two pieces of polyethylene film which are placed between sodium chloride windows of ordinary demountable liquid cell. The absorption bands due to polyethylene and Nujol are compensated by placing the polyethylene film of suitable thickness in the reference beam. The absorption bands due to solvents such as water can also be compensated by the polyethylene film cell sandwitched solvent of suitable thickness in the reference beam. This method would be a simple new technique. Especially this technique may offer a new helpful way for the investigation of the state of substances in aqueous system. Using this technique, authors have observed the appearance of an absorption bands at 3.2 micron, in the spectrum of phenol in aqueous solution, that is absent in the spectrum of phenol in benzene solution. The same absorption band also has been observed in the spectra of aqueous formaldehyde solution and aqueous polyvinyl alcohol solution, where the absorption bands due to polyethylene and water are compensated. Although it may be regarded that this absorption band is related to the intermolecular interaction between water and the solute having OH group, that is hydrogen bonding. The exact assignment of this absorption band is out of this work.

• 한국세라믹학회지
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• 제56권6호
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• pp.601-605
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• 2019

This work reports the preparation of ceramic hybrid films with illite-polyethylene composites analyzed as a function of concentration of added illite in polyethylene. The enhancement of oxygen and water-vapor transmission rate of illite-polyethylene film was evaluated to determine its influence on the freshness in fruit packaging. Particle size of illite materials was controlled in the range of 1~10 ㎛ and then mixed with LDPE to form the masterbatch. Ceramic hybrid films were prepared through a blown film making process. To determine the dispersity and abundancy of illite materials in the polyethylene matrix, various characterizations of illite-PE hybrid masterbatch and films were performed using SEM, TGA, and FT-IR. The oxygen and water-vapor transmission rate of illite-polyethylene film was found to be two times higher than that of LDPE film.

• 한국식품영양과학회지
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• 제15권1호
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• pp.39-44
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• 1986

Kacdugi fermented in the subatomospheric pressure(350mmHg) and polyethylene film package to improve the quality and to investigate the effect of fermentative control at $25^{\circ}C$. Brix degree, acidity, vitamin C content and number of total microbe and Lactobacilli was determined and also, the edible period of kacdugi was checked up by sensory assessment. The increasing rate of brix degree during kacdugi fermentation was high in the subatomospheric pressure, but decreased at the last period of fermentation as same tendency to the control, and it was preferably increased at the last period of fermentation in the polyethylene film package. However, the acidity was higher in the control than sbuatomospheric pressure but it was low in the polyethylene film package. Vitamin C content was high in the control at beginning and middle period of fermentation but high in sbuatomospheric pressure, and was low in the polyethylene film package at the last period of fermentation. The number of Lactobacilli was more in the subatomospheric pressure and polyethylene film package than the control, but it was suddenly incressed for the total microbe in the polyethylene film package at last period of fermentation. The edible periods of kacdugi by the sensory assessment of sour flavor, hardness and complex flavor was second days in the control. third days in the polyethylene film package, and fifth days in the subatomospheric pressure after soaking.

• 한국세라믹학회지
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• 제55권1호
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• pp.85-89
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• 2018

This work reported the preparation and evaluation of a freshness-keeping film prepared by composite of a porous ceramic material such as vermiculite and polyethylene polymer. The ceramic material was pretreated physically and chemically to control the specific surface areas and particle size. A high content master-batch was prepared using the pretreated vermiculite. The master-batch, which contained 30% ceramic material, was mixed with a polymer material to prepare a film containing 3% vermiculite. The oxygen permeability and various physicochemical properties were evaluated for the prepared films. Compared to plain polyethylene film, the vermiculite loaded polyethylene film has a freshness maintenance property, indicating the creation of an improved film.

• 한국자원식물학회지
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• 제9권2호
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• pp.177-181
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• 1996

우리나라 황칠나무의 주요 자생지인 완도지방에서 황칠나무의 재배시 생육을 촉진 시키는 방법을 연구하고자, 피복의 재료별로 멀칭시험을 실시한 결과는 다음과 같다. 멀칭에 의한 토양 수분함량과 지온은 무멀칭가 짚피복에 비하여 투명 P.E 멀칭과 검정 P.E 멀칭이 높은 경향이었다. 황칠나무의 재배시 Pot 육묘한 $2\sim3$년생의 묘목을 이식재배 할 경우, 투명 P.E 벌칭재배는 묘목의 활착율을 높이고, 월동기간 지표의 보온으로 지온이 상승하여 추기 생장이 촉진되어 알맞은 멀칭재료로 생각된다. 그러나 Pot 육묘한 묘목의 투명 P.E 멀칭재배시 잡초의 발생이 증가됨으로 멀칭이 반드시 재초 작업이 이루어져야 한다. 노동력의 부족으로 제초작업이 이루어지지 않을 경우, 검정 P.E 멀칭재배는 잡초의 발생이 억제되어 투명 P.E 멀칭재배보다 잡초의 발생량이 감소되므로 권장할 만한 멀칭재로로 생각된다.

• 한국약용작물학회지
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• 제12권1호
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• pp.85-88
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• 2004

우리 나라에서 비교적 온난한 남부 도서지역인 진도지방에서 강황의 멀칭재배를 실시한 바, 진도지역에서 강황을 4월 30일 정식할 경우 4주 후에 출현되고, 출현율은 $80{\sim}88%$이었다. 강황의 초장은 $97{\sim}137\;cm$로서 1주의 근경중은 $759{\sim}983\;g$ 이었으며, 10a 당 수량은 약 $3,567{\sim}4,620\;kg$이였다. 강황의 재배시 초장은 무피복에 비하여 멀칭재배에서 크고, 멀칭은 PE 필름에서 생장이 촉진되었다. 이러한 결과로 보아 진도에서 강황을 PE 필름으로 멀칭 재배할 경우 어느 정도 수확이 가능하였다. 특히 흑색 PE 필름으로 밀칭채대를 하면 근경이 비대 되고, 영농의 가장 큰 장해요인인 잡초도 방제할 수 있어 농가에 장려할 만한 재배법으로 판단된다.

• 한국수산과학회지
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• 제33권5호
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• pp.418-422
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• 2000

생분해성이며 가식성 어분 단백질 필름을 가공하기 위한 기초 자료로써 명태어분 단백질 필름의 가공조건에 따른 인장강도, 신장률 및 색의 변화를 측정한 결과는 다음과 같다. 명태어분단백질 용액의 캐스팅량이 증가할수록 명태어분단백질 필름의 인장강도와 신장률은 증가하였다 반면 glycerol의 첨가량이 증가하고, 명태어분단백질 용액의 pH가 낮을수록 필름의 인장강도와 신장률은 떨어졌다. 가소제의 종류별에 따른 인장강도는 sorbitol, polyethylene glycol 및 glycerol 첨가 필름의 순으로 높게 나타났으며, 신장률은 polyethylene glycol 첨가 필름이 가장 높았고 sorbitol 및 glycerol 첨가 필름은 서로 비슷하였다. 명태어분단 백질 용액의 농도가 진할수록 필름의 인장강도도 증가하였으나, 신장률은 비슷한 경향을 나타내었다. 상대습도를 달리하여 필름을 저장한 결과 상대습도가 높을수록 인장강도는 감소하였고 신장률은 증가하였다. 가소제의 종류가 필름의 색에 미치는 효과에서 L(밝기)과 b (황객도)는 sorbitol 첨가 필름이 가장 높았고, a (적색도)와 전체적인 색의 차이 (${\delta}E$)는 polyethylene glycol 첨가 필름이 가장 높았다.

• 폴리머
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• 제25권4호
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• pp.594-601
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• 2001

표면을 개질시켜 극성기를 도입한 다음 열융착시키는 방법으로 접착제를 사용하지 않고도 폴리에틸렌 필름과 알루미늄 판을 직접 접합시킬 수 있는지를 살펴보았다. 폴리에틸렌 필름은 산소 및 아크릴산 플라즈마로 처리하여 극성기를 도입하였으며, 알루미늄 판은 끓는 물로 처리하거나 diaminocyclohexane 플라즈마로 처리하여 극성기를 도입하였다. 폴리에틸렌 필름의 표면만을 개질시킬 경우에도 상당히 높은 접착력을 얻을 수 있었으며, 알루미늄 판의 표면까지 개질시킬 경우에는 접착시험시 폴리에틸렌 필름이 끊어질 정도로 높은 접착력을 얻을 수 있었다. 특히, 아크릴산플라즈마로 처리한 폴리에틸렌 필름과 diaminocyclohexane 플라즈마로 처리한 알루미늄 판을 접합시킬 경우에는 필름 표면의 카르복실기와 판 표면의 아민기가 반응하여 아마이드 그룹을 형성하는 화학적 결합에 대한 가능성도 보여주었다.