• Korean Journal of Food Science and Technology
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• v.21 no.2
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• pp.235-237
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• 1989

Water vapor permeability of plastic films was measured by Electric tester and Cup tester and the data of the two were compared. Regardless of the testing method, water vapor permeability measured by two methods showed consistent results. By these methods, water vapor permeability of polyethylene film was $21.25g/m^2$. 24h and $5.4g/m^2$. 24h for 0.045mm and 0.08mm thickness, respectively. The water vapor permeability of casted polypropylene film was 14.93 and $14.90g/m^2$. 24h for Electric tester and Cup tester, respectively. In conclusion, the data obtained by Cup tester was consistent with those of the Electric tester. The Cup tester was certified to perform the water vapor pormeability testing method.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.5 no.1
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• pp.37-46
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• 1999

Water vapor permeability of films is commonly calculated from the water vapor transmission rate of the film measured using a permeability cup method which is essentially a gravimetric method. This method was originally developed for petroleum based plastic films with low water vapor permeability. In the case of hydrophilic bio-polymer films, the resistance caused by a stagnant air layer, which is developed between the underside of the film mounted on the cup and the surface of the desiccant saturated salt solution or distilled water, can be significant and, if neglected, ran lead to underestimation of water vapor transmission rates. Therefore, it is necessary to correct water vapor transmission rate data to accurately estimate the water vapor permeability of bio-polymer films.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.186-186
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• 2015

We have introduced multifunctional ITO single thin films formed by normal sputtering system equipped with a plasma limiter which effectively blocks the bombardment of energetic negative oxygen ions. MFSS ITO also possesses high gas diffusion barrier properties simultaneously low resistivity even it deposited at room temperature without post annealing on plastic substrate. Nano-crystalline enhancement by Ar energy has energy window from 20 to 30 eV under blocking NOI condition. Effect of blocking NOI and optimal Ar energy window enhancement facilitate that resistivity is minimized to $3.61{\times}10^{-4}{\Omega}cm$ and the WVTR of 100 nm thick MFSS ITO is $3.9{\times}10^{-3}g/(m^2day)$ which is measured under environmental conditions of 90% relative humidity and 50oC that corresponds to a value of ${\sim}10^{-5}g/(m^2day)$ at room temperature. The multifunctional MFSS ITO with low resistivity, and low gas permeability will be highly valuable for plastic electronics applications.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.162-162
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• 2016

We present multifunctional indium tin oxide (ITO) thin films formed at room temperature by a normal sputtering system equipped with a plasma limiter which effectively blocks the bombardment of energetic negative oxygen ions (NOIs). The ITO thin film possesses not only low resistivity but also high gas diffusion barrier properties even though it is deposited on a plastic substrate at room temperature without post annealing. Argon neutrals incident to substrates in the sputtering have an optimal energy window from 20 to 30 eV under the condition of blocking energetic NOIs to form ITO nano-crystalline structure. The effect of blocking energetic NOIs and argon neutrals with optimal energy make the resistivity decrease to $3.61{\times}10-4{\Omega}cm$ and the water vapor transmission rate (WVTR) of 100 nm thick ITO film drop to $3.9{\times}10-3g/(m2day)$ under environmental conditions of 90% relative humidity and 50oC, which corresponds to a value of ~ 10-5 g/(m2day) at room temperature and air conditions. The multifunctional ITO thin films with low resistivity and low gas permeability will be highly valuable for plastic electronics applications.

• 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.

• Food Science and Biotechnology
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• v.16 no.5
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• pp.691-709
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• 2007

Concerns on environmental waste problems caused by non-biodegradable petrochemical-based plastic packaging materials as well as consumer's demand for high quality food products has caused an increasing interest in developing biodegradable packaging materials using annually renewable natural biopolymers such as polysaccharides and proteins. However, inherent shortcomings of natural polymer-based packaging materials such as low mechanical properties and low water resistance are causing a major limitation for their industrial use. By the way, recent advent of nanocomposite technology rekindled interests on the use of natural biopolymers in the food packaging application. Polymer nanocomposites, especially natural biopolymer-layered silicate nanocomposites, exhibit markedly improved packaging properties due to their nanometer size dispersion. These improvements include increased mechanical strength, decreased gas permeability, and increased water resistance. Additionally, biologically active ingredients can be added to impart the desired functional properties to the resulting packaging materials. Consequently, natural biopolymer-based nanocomposite packaging materials with bio-functional properties have huge potential for application in the active food packaging industry. In this review, recent advances in the preparation and characterization of natural biopolymer-based nanocomposite films, and their potential use in food packaging applications are addressed.

• Food Science of Animal Resources
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• v.36 no.3
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• pp.421-426
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• 2016

Polylactic acid (PLA) is a biodegradable and renewable polymer, which represents a valuable alternative to plastic packaging films, often associated with environmental problems. In this study, we tested the suitability of PLA as a biodegradable packaging film and assessed the antimicrobial activity of lemongrass oil (LO), incorporated into the PLA film in different concentrations. To obtain the optimal physical properties for PLA films, tensile strength, elongation at break, and water vapor permeability were measured under different preparation conditions. In addition, the antimicrobial activity of the LO contained in the PLA film against Listeria monocytogenes was investigated by disc diffusion and viable cell count. Among all concentrations tested, 2% LO was the most suitable in terms of antimicrobial activity and physical properties of the PLA film. Based on these results, we used the PLA film containing 2% LO to pack pork sausages; after 12 d of storage at 4℃, the population of inoculated L. monocytogenes in the sausage samples wrapped with the PLA film containing 2% LO was reduced by 1.47 Log CFU/g compared with the control samples. Our data indicate that PLA films containing 2% LO represent a valuable means for antimicrobial sausage packaging.

• Food Science and Biotechnology
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• v.15 no.5
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• pp.683-687
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• 2006

The respiration rate of Chinese quince was measured at 0, 5, 10, and $20^{\circ}C$ to determine its tolerable range of storage temperatures. Based on the measured respiration rates, plastic films covering a wide range of gas permeabilities were used for packaging and storing individual Chinese quince at 0 and $10^{\circ}C$. Chinese quince can be categorized as low respiration fruit. Higher respiratory quotients were observed at higher temperature suggesting that the tolerable temperature range for storage is $0-10^{\circ}C$. Packages containing Chinese quince wrapped in highly gas-permeable polyolefin film PD 941 attained, with progressive decreases in volume, 9.5-10.2% $O_2$ and 1.3-1.8% $CO_2$ at $0^{\circ}C$, 8.1% $O_2$ and 2.4% $CO_2$ at $10^{\circ}C$. At these levels, PD 941 could preserve the fruit at acceptable quality levels for 152 and 50 days at 0 and $10^{\circ}C$, respectively. Less gas-permeable packages built up high $CO_2$ concentrations (above 15.8%) and low $O_2$ concentrations (less than 1.8%) causing free volume expansion and eventual dark discoloration of the fruit. The storage life realized by packaging with polyolefin film PD 941 could facilitate the availability of Chinese quinces in winter and spring for medicinal or ornamental purposes in the fresh state.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.6
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• pp.5-21
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• 2015

The common production methods of nanocellulosic (cellulosic nanofibrils, CNF) materials from wood are being reviewed, together with large scale applications and particularly papermaking applications. The high energy demand for producing CNF has been one particular problem, which has been addressed over the years and can now be considered solved. Another problem was the clogging of homogenizers/microfluidizers, and the different routes to decrease the energy demand. The clogging tendency, related to the flocculation tendency of fibres is discussed in some detail. The most common methods to decrease the energy demand are TEMPO-oxidation, carboxymethylation and mechanical/enzymatic pre-treatments in the order of increased energy demand for delamination. The rheology characteristics of CNF materials, i.e. the high shear viscosity, shear thinning and the thixotropic properties are being illuminated. CNF materials are strength adjuvants that enhance the relative bonded area in paper sheets and, hence increase the sheet density and give an increased strength of the paper, particularly for chemical pulps. At the same time papers obtain a lower light scattering, higher hygroexpansion and decreased air permeability, similar to the effects of beating pulps. The negative effects on drainage by CNF materials must be alleviated through the appropriate use of microparticulate drainage aids. The use of CNF in films and coatings is interesting because CNF films and coatings can provide paper/board with good oxygen barrier properties, particularly at low relative humidities. Some other high volume applications such as concrete, oil recovery applications, automotive body applications and plastic packaging are also briefly discussed.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.2
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• pp.429-437
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• 1999

A mathematical model was established for estimating changes in pressure and volume of permeable kimchi packages. The model comprises the CO2 gas production from kimchi and permeation of O2, CO2 and N2 through the permeable film or sheet. Using the developed model, the effects of various packaging variables on the pressure and volume changes were analyzed for rigid and flexible packag es of kimchi(3% salt content) at 15oC, and then effect of storage temperature was also looked into. In case of rigid pack of 400g, using the plastic sheet of high CO2 permeability and initial vacuumizing can help to relieve the problem of pressure build up. The lower fill weight can further reduce the pressure, but will result in higher packaging cost. For the flexible package of 3 kg, highly permeable films such as low density polyethylene(LDPE) and polypropylene can reduce the volume expansion. Higher ratio of CO2 permeability to O2 and N2 permeabilities are effective in reducing the volume expansion. Increased surface area cannot contribute to reduction of volume expansion for highly permeable flexible packages of kimchi. For the impermeable packages, pressure and volume at over ripening stage (acidity 1.0%) increase with decreased temperature, while those at optimum ripening stage(acidity 0.6%) change little with temperature. Pressure of permeable rigid LDPE package increases with tem perature at any ripening stage, and temperature affects the volume of flexible LDPE package very slightly. Experimental verification of the present results and package design with economical consid eration are needed as a next step for practical application.