• Food Science and Preservation
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• v.9 no.2
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• pp.148-153
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• 2002

Effect of the thickness of low density polyethylene(LDPE) Film as packaging material on changes in physicochemical characteristics of mature-green mume (Prunus mume Sieb. et Zucc) fruits during storage at different temperatures(0, 10 and 25$\^{C}$) were investigated. Fruit samples stored in pouches with 30㎛ thickness of LDPE film maintained well not only external qualities such as Shape and firmness, but also internal chemical properties such as pH, acidity, the content of soluble solid and chlorophyll, and color, comparing with samples stored without packaging material or in other pouches with different film thickness(20 and 40㎛). From the results, it was found that the maintenance of quality of mature-green mume fruits during storage at 0, 10 and 25$\^{C}$ closely related to the changes in respiratory conditions for fruits affected by the film thickness of the packaging material.

• Food Science and Preservation
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• v.6 no.3
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• pp.264-269
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• 1999

The effects of film thickness and moisture absorbing materials(MAM) on the ginger qualities were investigated during MA storage for 150 days. LDPE films of 0.04, 0.06 and 0.08mm thicknesses were applied to select the adequate film in gas permiability. MAMs of sheet and sachet type were applied to 0.06mm-LDPE film bag to prevent moisture condensation during storage. Thickness of film used affected neither weight loss nor firmness of gingers during U storage. But the thinner in thickness showed the less changes in sprouting, spoilage and reducing sugar. Moreover, compared with MAP alone, MAPs with MAM of both sachet and sheet styles led to the weight loss of gingers increasing by more than 3-4 times, but sprouting rate, spoilage rate and reducing sugar decreasing by 3.3, 1.4 and 2.3 times, respectively. These results showed that MAP with UM was significantly effective to prolong the freshness of ginger by longer than 2 times, compared with MAP alone.

• Journal of Bio-Environment Control
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• v.14 no.2
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• pp.69-75
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• 2005

The storability of chicon was compared by packing it with PE box, wrap, LDPE (low density polyethylene) film that was 25 and 50um thickness, respectively and storing at 1 and $10^{\circ}C$ under light and dark conditions. The visual quality depending on dehydration was deteriorated at more than $2\%$ weight loss during storage. In packing treatments, chicon packed with PE box lost fresh weight to $3\%\;at\;10^{\circ}C\;and\;2\%\;at\;1^{\circ}C$, while non- penetrated film treatment, wrap, 25 and 50um thickness LDPE film, showed less than $1\%$ weight loss. The carbon dioxide concentration in package was $3\~4\%\;in\;50{\mu}m$ LDPE film at $1^{\circ}C\; and\;25um$ LDPE film at $10^{\circ}C$. The ethylene concentration in 50um LDPE film at $1^{\circ}C\;and\;25{\mu}m$ LDPE film at $10^{\circ}C$ was approximately 0.3 ppm and 0.5 ppm, respectively. Chiton stored in dark condition didn't turn to green, but it fumed green only in 3 days at $10^{\circ}C$ and in 6 days at $1^{\circ}C$ under light condition. The greening of chicon was less, the packing materials was thicker. The chlorophyll content represented the degree of greening showed less at $1^{\circ}C$ then at $10^{\circ}C$. The coefficient of correlation(r) between chlorophyll content and carbon dioxide concentration in package was 0.926 at $1^{\circ}C$ and 0.997 at $10^{\circ}C$. The visual quality except greening of packed chicon was maintained at $1^{\circ}C$ better than $10^{\circ}C$, and it was shown highest grade packed with $50{\mu}m$ LDPE film at $1^{\circ}C$ and packed with 25um LDPE film at $10^{\circ}C$. The vitamin C content in packed chicon was kept higher at $1^{\circ}C$ on storage temperatures, and 25um and 50um LDPE film on packing materials. According to these results, it can be proper condition for storage and marketing of chicon that 50um LDPE film at $1^{\circ}C$ and 25um LDPE film at $10^{\circ}C$. And dark condition is necessary to store chicon because it should turn green under tiny light condition.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.349-350
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• 2007

Polyethylene is widely used as the insulator for power cable. To investigate the conduction mechanism for power cable insulation under ac high field, it is very important to acquire the dissipation current under actual running field. Recently, we have developed the unique system, which make possible to observe the nonlinear dissipation current waveform. In this system, to observe the nonlinear properties with high accuracy, capacitive current component is canceled by using inverse capacitive current signal instead of using the bridge circuit for canceling it. As the results of these estimations, it was found that the dissipation current will depend on not only the instantaneous value of electric field but also the time differential of applied electric field due to taking a balance between applied field and internal field. Furthermore, two large peaks of dissipation current for each half cycle were observed under certain condition. In this paper, to clarify the reason why it shows two peaks for each half cycle, the film thickness dependences of dissipation current waveforms were observed by using the three different thickness LDPE films.

• Journal of the Korean Society of Food Science and Nutrition
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• v.17 no.3
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• pp.191-197
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• 1988

Sorption properties of corn starch(CS) and Soy protein isolates(SPI) in plastic films packaging were investigates for binary system. The mixture were sealed in plastic films of low density polyethylene(LDPE), oriented polypropylene(OPP) and LDPE/OPP coated film and packaging effect on the changes of moisture sorption during storage at $40^{\circ}C$ were studied. The following results were obtained. The water vapor permeability of material films was $32.6g/m^2/24hrs(below\;g)$ for 0.02mm LDPE film, 14.01g for 0.04mm LDPE film, 7.30g for 0.02mm OPP film, 3.37g for 0.04mm OPP film and 4.869 for 0.02mm LDPE/0.02 mm OPP confine film at $40^{\cire}C$ 90%RH, therefore the OPP film was more effective than LDPE film on the resistance of relative humidity. And the OPP film packaging sealed mixture of food samples was also more elective then LDPE film, having same thickness for increase of water vapor permeability during storage at $40^{\cire}C$. A general increase in sorption rate was found more in SPI than CS in the packaged mixtures.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.4
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• pp.621-628
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• 2002

Effect of the thickness of packaging film on the ripening of mature-green mume (Prunus mume Sieb. et Zucc) fruit was investigated by measuring physicochemical changes of the fruit during storage. Fruits were packaged using low density polyethylene (LDPE) films with thicknesses of 20, 30, and 40$\mu$m and stored at the room temperature. The physicochemical properties such as contents of various pectic substances, molecular weight distribution of soluble pectic substances, and surface image of the fruit were determined during storage of 8 days. In general, regardless of the thickness of the films applied, a content of water-soluble pectin (WSP) in the fruit was increased during storage, but both contents of HCI- soluble pectin (HSP), and Ca and Mg in total alcohol-insoluble solids were decreased. Sephacryl S-300 gel filtration study revealed that fractions of high molecular weight HSP and WSP decomposed into lower molecular weight pectins during storage. The scanning electronic microscope also identified a significant structural change of the fruit skin over the storage time. It could be concluded from the results that fruits packaged with LDPE 30${\mu}{\textrm}{m}$ film maintained the highest physicochemical quality of green mume fruit during storage.

• Journal of the Korean Chemical Society
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• v.23 no.5
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• pp.329-337
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• 1979

The water-vapour transmission ratios (WVTR) of the various commercial polymer films have been investigated at the constant pressure and relative humidity (RH). Water proofnesses, the reciprocals of WVTR for the various samples, were determined using a cup device and maintaining the sample films at a constant temperature ($40{\pm}1^{\circ}C$) and a constant R. H ($90{\pm}2%$) for 24 hours. The following order of the relative proofness was observed; oriented polypropyrene (O.PP) > high density polyethylene (HDPE, Inflation) > high density polyethylene (HDPE. T-die) > casted polypropylene (C. PP) > nonoriented polyester (N. PET) > low density polyethylene (LDPE) > oriented polyester (O. PET) > rigid polyvinyl chloride (Rigid PVC) > semirigid polyvinyl chloride (Semirigid PVC) > nonrigid polyvinyl chloride (Nonrigid PVC) > oriented nylon (O. Nylon) > nonoriented nylon (N. Nylon). And water proofness order was also observed to decrease with the temperature rising; HDPE (T-die) > C. PP > O. PET > LDPE > O. Nylon. The activation energies of LDPE, HDPE (T-die), C. PP, O. PET and O.Nylon films were 12.0, 11.1, 11.4, 11.7, 14.1 kcal/mole, respectively. The WVTR's of the films were increased with the polarity of polymer and the addition of plasticizer in PVC, decreased with the increase of the film thickness and mechanical orientation. The WVTR's of the laminated films O. PP/LDPE, N.Nylon/LDPE, C.PP/LDPE were also more dependent on the film thickness than the WVTR's of the single films.

• Electrical & Electronic Materials
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• v.10 no.5
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• pp.453-460
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• 1997

In order to investigate the electrical conduction properties of polyethylene thin film for power cable with manufacturing methods, the thickness of specimen was the 30, 100[${\mu}{\textrm}{m}$] of LDPE and 200[${\mu}{\textrm}{m}$] of XLPE were manufactured. The experimental condition for conduction properties was measured until the breakdown occurs at temperature ranges from 30 to 110[$^{\circ}C$] and the electric field from 1$\times$10$^3$to 5$\times$10$^{6}$ [V/cm]. As for increase of temperature, the current density of LDPE was increased with constant ratio in low field, but changes with exponential function in high electric field. The tunnel current of pre-breakdown region is shifted toward low field as much as thermal excitation energy. At low electric field, the XLPE showed dominant electrical conduction properties by thermal excitation, and transformation of the electron was resisted by the crystal at high electric field.

• Journal of Bio-Environment Control
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• v.5 no.1
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• pp.23-33
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• 1996

This study was performed to induce a quality improvement and standardization of materials used for greenhouse. For this purpose, physical and mechanical properties of agricultural films for greenhouse were measured by kinds and thickness of the films. The properties are composed of impact, tensile, tear propagation strength and light transmittance. The results were summarized as follows. 1. At the impact test result of the falling dart, the thicker the film, the greater the impact strength of soft film. The impact weight at 50 percents is from 158g to 213g and the strength of low density polyethylene(LDPE) film is higher than the rest of any other films. 2. Seeing the leveling of the impact rupture, maximum impact weight which was ruptured very little ranges from 62g to 192g. The impact strength of 0.1mm films was higher than that of 0.05mm as from 1.8 to 3.2 times. 3. Tensile weight covers from 0.95kg to 2.22kg in the test materials, and the weight of lengthwise film is larger than that of width. LDPE film has high value of tensile weight. Elongation range is from 345 to 102 percent and lengthwise elongation is greater than width as much as from 1.4 to 2.7 times. 4. Tea. propagation strength ranges from 80.5kg/cm to 121.7kg/cm, and unlike which of LDPE film has high value, EVA film has low value in the films tested. The width strength is higher than the lengthwise. 5. The light transmittance of the soft film is about 78-92 percent in the range of ultraviolet ray, but has high value in the visible ray range.

• Resources Recycling
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• v.12 no.1
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• pp.48-54
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• 2003

Odor-removing polyethylene film utilizing waste shell powder (annual production: 250,000 ton) was prepared. Odor removal was designed to work by cation or cationic surfactant adsorbed onto the shell surface by ion-exchange: cationic surfactants (DTAB (n-dodecyltrimethylammonium bromide), CTAB (n-cetyltrimethylammonium bromide) and DHAB (n-dihexade-cyldimethylammonium bromide), and cations $Ce^{3+}$ , $Mg^{2+}$ and $Al^{3+}$) were used. Surface-modified waste shell powder was com-pounded with LDPE to produce 20 wt% shell masterbatch (MB), and the MB was again blended with LDPE to get shell-containing LDPE films with 3,5, 10 wt% of shell (width: 40 cm, thickness: 40 $\mu\textrm{m}$). Mechanical properties of the various shell-LDPE films maintained more than 80 % of that of pure LDPE film. Both shell film modified with cationic surfactant and one without shell surface-modification showed excellent odor-removing ability.