• Journal of Biosystems Engineering
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• v.15 no.1
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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.

• Korean Journal of Weed Science
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• v.5 no.1
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• pp.19-23
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• 1985

Soil temperature was higher in clear or blue polyethylene film and bare soil than in black or green polyethylene film and straw mulching. Light transmission was low in black, blue or green colored polyethylene film and straw mulching. Germination of weeds was generally high under clear polyethylene film but black polyethylene film inhibited the germination. Germination of Portulaca oleracea, Setaria viridis and Amaranthus retroflexus increased under blue polyethylene film but inhibition of germination was observed in Erigeron canadensis, Avena fatua, Chenopodium ablum, Digitaria sanguinalis and Echinochloa crusgalli. Green polyethylene film mostly inhibited germination of weeds except A, fatua, C. album and E. canadensis. The greatest number of weeds emerged was obtained in clear polyethylene film, next in bare soil but green or blue polyethylene film inhibited the emergence of weeds. However, no emergence of weeds was observed under black polyethylene film. The highest dry weight of weeds was obtained in clear polyethylene film, next in bare soil, but green or blue polyethylene film and straw mulching caused suppression of weed growth. No weeds were grown under black polyethylene film.

• Journal of the Korean Chemical Society
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• v.7 no.1
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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.

• Journal of the Korean Ceramic Society
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• v.56 no.6
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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.

• Journal of the Korean Society of Food Science and Nutrition
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• v.15 no.1
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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.

• Journal of the Korean Ceramic Society
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• v.55 no.1
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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.

• Korean Journal of Plant Resources
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• v.9 no.2
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• pp.177-181
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• 1996

This study was carried out to obtain basic data for technical inprovement about cultivation according to micrometerological changes under various mulching materials in Dendropanox morbifera LEV. The results are summarized as follows. Transparent polyethylene film and black polyethylene film mulching materials increased the soil porosity and reduced change of the soil moisture content. The rate of missing plant during overwinter increased in the control plot. Growth of Dendropanox morbifera LEV, was accelerated by transparent polyethylene film and black polyethylene film mulched.

• Korean Journal of Medicinal Crop Science
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• v.12 no.1
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• pp.85-88
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• 2004

This study was carried out to obtain basic information on cultivation of Curcuma longa L. in southern part of Korea. The results were summaried as follows. Mulching of both transparent polyethylene film and black polyethylene film improved the soil characters such as soil porosity and soil moisture content. The rate of emergency after winter was increased by mulching. Growth of Curcuma longa L. was accelerated by mulching of transparent polyethylene film and black polyethylene film mulched.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.5
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• pp.418-422
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• 2000

The tensile properties and color of fish meal film under various processing conditions were measured to obtain basic data for biodegradable Alaska Pollack meal protein isolate (APMPI) film. The tensile strength and the elongation of APMPI film were increased with casting volume of APMPI solution but those of APMPI film were weakened with the addition of glycerol amount as well as reduction of pH values. In case of adding various plasticizer, the tensile strength of film was increased in order as follows: sorbitol, polyethylene glycol and glycerol. The elongation was increased in order of polyethylene glycol, sorbitol and glycerol. The tensile strength of film increased with increment of APMPI concentration, but the elongation of film was not affected by APMPI concentration. The tensile strength of APMPI film was decreased with the increment of relative humidity but its elongation was increased with the increment of relative humidity, Not only lightness and yellowness of film added with sorbitol but also redness and total different color of film added with polyethylene glycol showed the highest value in Hunter color system.

• Polymer(Korea)
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• v.25 no.4
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• pp.594-601
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• 2001

Direct thermal lamination of polyethylene film on aluminum plate without using adhesive was tried by modifying their surfaces to have polar groups. Polyethylene film was modified by treating with oxygen or acrylic acid plasma. Aluminum plate was modified by treating with boiling water or diaminocyclohexane plasma. Fairly high adhesion strength was obtained even in the case when only the polyethylene film was modified, and adhesion strength was so high that film was broken during the adhesion test if both the film and the aluminum plate were modified. Even chemical bonding seemed to be possible when the film treated with acrylic acid was laminated on the plate treated with diaminocyclohexane plasma by forming amide linkage through the reaction between COOH groups on the film surface and NH$_2$ groups on the plate surface.