• Journal of Applied Biological Chemistry
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• v.61 no.1
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• pp.25-31
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• 2018

This study investigated the effect of different $O_2$ transmission rate (OTR) of films on surface temperature, weight loss, pH, $O_2$, $CO_2$ and sensory characteristics, microbial quality, total phenolic contents and 1,1-diphenyl-2-picryl hydrazyl radical scavenging activity of fresh-cut lettuce during storage at $10^{\circ}C$ for 7 days. $80{\pm}5g$ of fresh-cut lettuce were packaged with oriented polypropylene films respectively. The OTR of packaging materials was 5,000, 8,000 and $10,000cc/m^2{\cdot}day{\cdot}atm$. Quality characteristics showed significant differences during storage. The surface temperature was averaged 13 and lower in higher OTR of films. The weight loss of lettuce ranged from 2.8 to 5.4% and the highest loss showed in $5,000cc/m^2{\cdot}day{\cdot}atm$ of film. pH was increased during storage and the highest pH was found in $5,000cc/m^2{\cdot}day{\cdot}atm$. The $O_2$ content in the packaging was decreased with increasing $CO_2$ content during storage. The lowest $CO_2$ was found in $10,000cc/m^2{\cdot}day{\cdot}atm$. As OTR was decreased, antioxidant profile of lettuce was decreased. Total aerobic bacteria showed from 5.48 to 6.59 log CFU/g. From the result of the overall sensory test, the marketability of fresh-cut lettuce stored at $10^{\circ}C$ seemed to be maintained effectively over 5 days.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.270-270
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• 2016

We fabricated an organic-inorganic nano laminated encapsulation layer using molecular layer deposition (MLD) combined with atomic layer deposition (ALD). The $Al_2O_3$ inorganic layers as an effective single encapsulation layer were deposited at 80 degree C using ALD with alternating surface-saturation reactions of TMA and $H_2O$. A self-assembled organic layers (SAOLs) were fabricated at the same temperature using MLD. MLD and ALD deposition process were performed in the same reaction chamber. The prepared SAOL-$Al_2O_3$ organic-inorganic nano laminate films exhibited good mechanical stability and excellent encapsulation property. The measurement of water vapor transmission rate (WVTR) was performed with Ca test. We controlled thickness-ratio of organic and inorganic layer, and specific ratio showed a lowest WVTR value. Also this encapsulation layer contained very few pin-holes or defects which were linked in whole area by defect test. To apply into real OLEDs panels, we controlled a film stress from tensile to compressive and flexibility defined as an elastic modulus with organic-inorganic ratio. It has shown that OLEDs panel encapsulated with nano laminate layer exhibits better properties than single layer encapsulated in acceleration conditions. These results indicate that the organic-inorganic nano laminate thin films have high potential for flexible display applications.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.635-635
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• 2013

We report three-dimensional polycrystalline anatase TiO2 structures (3D a-TiO2) for environmental and bio-medical applications. The 3D a-TiO2 was synthesized without thermal treatment by the growth of rod-like polycrystals on Degussa P25 (P25) via low temperature (< $85^{\circ}C$) modified alkali hydrothermal processing. X-ray diffraction and high-resolution transmission electron microscopic results showed that the rod-like polycrystals of 3D a-TiO2 possessed the highly anatase nanostructures. The photocatalytic activity of 3D a-TiO2 was found to be 2.2 times higher than that of P25. The recyclability of the 3D a-TiO2 was found to be high: the decolorization rate was 94.8% of the initial value after fifteen cycles. In addition, 3D a-TiO2 exhibited excellent antibacterial activities for the sterilization of gram-negative Escherichia coli (E. coli) and gram-positive Staphylococcus aureus (S. aureus). Even at the 10th recycled use, more than 98.4% of E. coli and S. aureus can be killed. These results indicated that 3D a-TiO2 might have utility in several promising applications such as photocatalytic water/air purification and bactericidal agents.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.425-425
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• 2011

The photocatalytic decomposition of toluene gas was investigated with $TiO_2$ on nano-diamond powder (NDP) under UV irradiation. Atomic layer deposition (ALD) was used for the growth of $TiO_2$ on the NDP. The structure and surface properties of catalysts were characterized by X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM). The photocatalytic activity for the toluene decomposition was evaluated by measuring the concentration change of toluene and $CO_2$ gas with gas chromatography (GC)-flame ionization detector (FID) system. The photocatalytic activities of $TiO_2$/NDP catalysts were compared with that of P-25. The rate of initial photocatalytic decomposition of toluene for the $TiO_2$/NDP catalysts was relatively lower when compared to P-25. The photocatalytic activity of P-25 was rapidly decreased with time, whereas, the deactivation of $TiO_2$/NDP catalysts was less pronounced. Therefore, as the reaction time increased, the photocatalytic activity of $TiO_2$/NDP catalysts became higher than that of P-25. The intermediates such as benzaldehyde or benzoic acid, etc were more easily adhered to the active site on the P-25 surface during reaction, resulting in easier deactivation of P-25. These results could be confirmed using FT-IR spectroscopy. We suggest that the NDP used as substrate can reduce the deactivation of $TiO_2$ on the surface.

• Journal of the Korean Society of Food Culture
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• v.34 no.2
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• pp.233-239
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• 2019

This paper presents a literature review on the active technologies to regulate the levels of carbon dioxide and oxygen in Kimchi packaging. In this study, laser-etched pouches and $O_2$ scavengers were used for Kimchi packaging, and the efficiency of each packaging technique to regulate the $CO_2$ and $O_2$ levels inside Kimchi packages was investigated. When Kimchi was packaged with a laser-etched pouch, the $CO_2$ concentration in the sample with a high gas transmission rate was less than that in other pouches (p<0.05), and a low $CO_2$ level had little effect on the expansion of the package volume. Kimchi treated with an $O_2$ absorber exhibited a significantly lower (p<0.05) $O_2$ concentration inside the packages relative to the control. A low $O_2$ concentration inside the Kimchi package effectively inhibited the growth of total aerobic bacteria and lactic acid bacteria, as well as yeasts and molds on Kimchi. These results suggest that $O_2$ absorbers have a positive effect on the microbial quality of Kimchi. Therefore, packaging in a laser-etched pouch and the use of an $O_2$ scavenger could provide a novel packaging material for regulating the $CO_2$ and $O_2$ levels during Kimchi packaging.

• Food Science and Preservation
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• v.20 no.5
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• pp.602-607
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• 2013

Correct packaging enables processors to pack fresh produce and extend its shelf life. This study was carried out to investigate the effect of different packaging materials on the weight loss, pH, $O_2$, $CO_2$ and sensory characteristics of soybean sprouts during their storage at $5^{\circ}C$ for seven days. Soybean sprouts ($320{\pm}20g$) were packaged with oriented polypropylene (OPP) and cast polypropylene (CPP) films, respectively. The $O_2$ transmission rate of the packaging materials was set to have a control of $10,000cc/m^2$.day.atm, and an OP15 and CP15 with $15,000cc/m^2$.day.atm through a pre-screening test. The average weight loss of the soybean sprouts during their storage was less than 10%, and that of the soybean sprouts with a CPP film was higher than that of the OPP film. The pH of the soybean sprouts increased during their storage regardless of their packaging materials; but compared to the pH of the soybean sprouts packaged with OPP, those packaged with CPP were higher. The $CO_2$ content of the packaging increased with a decrease in the $O_2$ content. The ratio of $CO_2$ to $O_2$ in the soybean sprouts with the OPP film was 3.5 times higher than in the soybean sprouts with the CPP film. The results of the overall sensory test showed that the marketability of the soybean sprouts packaged with OPP film and stored at $5^{\circ}C$ seemed to have been maintained effectively for six days (at a $15,000cc/m^2$.day.atm $O_2$ transmission rate). When the correlation coefficients of the control, OP15 and CP15 were analyzed, the highest correlation was shown between a control and OP15 (0.986; p<0.01).

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.198.1-198.1
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• 2016

Organic light-emitting diode (OLED) displays have promising potential to replace liquid crystal displays (LCDs) due to their advantages of low power consumption, fast response time, broad viewing angle and flexibility. Organic light emitting materials are vulnerable to moisture and oxygen, so inorganic thin films are required for barrier substrates and encapsulations.[1-2]. In this work, the silicon-based inorganic thin films are deposited on plastic substrates by plasma-enhanced chemical vapor deposition (PECVD) at low temperature. It is necessary to deposit thin film at low temperature. Because the heat gives damage to flexible plastic substrates. As one of the transparent diffusion barrier materials, silicon oxides have been investigated. $SiO_x$ have less toxic, so it is one of the more widely examined materials as a diffusion barrier in addition to the dielectric materials in solid-state electronics [3-4]. The $SiO_x$ thin films are deposited by a PECVD process in low temperature below $100^{\circ}C$. Water vapor transmission rate (WVTR) was determined by a calcium resistance test, and the rate less than $10.^{-2}g/m^2{\cdot}day$ was achieved. And then, flexibility of the film was also evaluated.

• Carbon letters
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• v.25
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• pp.84-88
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• 2018

At present, an important research area is the search for materials that are compatible with CMOS technology and achieve a satisfactory response rate and modulation efficiency. A strong local field of graphene surface plasmon polariton (SPP) can increase the interaction between light and graphene, reduce device size, and facilitate the integration of materials with CMOS. In this study, we design a new modulator of SPP-based cycle branch graphene waveguide. The structure comprises a primary waveguide of graphene-$LiNbO_3$-graphene, and a secondary cycle branch waveguide is etched on the surface of $LiNbO_3$. Part of the incident light in the primary waveguide enters the secondary waveguide, thus leading to a phase difference with the primary waveguide as reflected at the end of the branch and interaction coupling to enhance output light intensity. Through feature analysis, we discover that the area of the secondary waveguide shows significant localized fields and SPPs. Moreover, the cycle branch graphene waveguide can realize gain compensation, reduce transmission loss, and increase transmission distance. Numerical simulations show that the minimum effective mode field area is about $0.0130{\lambda}^2$, the gain coefficient is about $700cm^{-1}$, and the quality factor can reach 150. The structure can realize the mode field limits of deep subwavelength and achieve a good comprehensive performance.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1779-1783
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• 2006

The hybrid thin-film (HTF) passivation layer composed of the UV curable acrylate layer and MS-31 (MgO:SiO2=3:1wt%) layer was adopted in organic light emitting diode (OLED) to protect organic light emitting materials from penetrations of oxygen and water vapors. The moisture resistance of the deposited HTF layer was measured by the water vapor transmission rate (WVTR). The results showed that the HTF layer possessed a very low WVTR value of lower than $0.007g/m^2$ per day at $37.8^{\circ}C$ and 100% RH. Therefore, the HTF on the OLED was found to be very effective in protect what from the penetrations of oxygen and moisture.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.23 no.2
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• pp.83-87
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• 2017

This study was conducted to determine types of oxygen transmission rate (OTR) films suitable for modified atmosphere (MA) storage treatment of strawberries (cv. 'Maehyang') for export and examination related changes in quality of strawberries during simulated shipping distribution conditions ($2^{\circ}C$ for $10days{\sim}8^{\circ}C$ for 11 days). Strawberries were packed by 1,300, 10,000, 20,000, and $30,000cc/m^2{\cdot}day{\cdot}atm$ OTR films for MA storage treatment and perforated film as the control for MAP. Fresh weight loss rate was less than 0.5% in OTR films except for the perforated film. Carbon dioxide and oxygen content in packages prevailed in permissible range for strawberries under recommended CA/MA conditions (i.e., $CO_2$: 15~20%, $O_2$: 5~10%) at 10,000 cc, 20,000 cc, and 30,000 cc OTR films. Ethylene content in OTR films did not reveal significant differences during storage. The 1,300 cc OTR film revealed highest off-flavor and lowest fungal incidence rate by sensory evaluation. The firmness, soluble solids, and visual quality were preserved the highest at 10,000 cc OTR film. In conclusion, 10,000 cc OTR film preserved the highest quality and extended shelf-life by 13 days if compared with conventional distribution conditions.