• Development and Reproduction
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• v.10 no.2
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• pp.147-154
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• 2006

Phthalates such as di(2-ethyl hexyl)phthalate(DEHP) are industrial chemicals with wide-ranging human exposures because of their use in plastics and other common consumer products. Consequently, their adverse effects as endocrine disruptor in the reproductive physiology of both laboratory rodents and human have been studied extensively. The present study was undertaken to examine whether prepubertal exposure to DEHP affects on the onset of puberty and the associated reproductive parameters such as hormone receptor expressions in female rats. DEHP(100mg/kg/day) was administered daily from postnatal day 25(PND 25) through the day when the first vaginal opening(VO) was observed, and the animals were sacrificed on the next day. Gross anatomy and weight of reproductive tissues were compared to test the DEHP's effects on the cell proliferation. Furthermore, histological studies were performed to assess the structural alterations in the tissues. Specific radioimmunoassay was carried out to measure serum LH levels. To determine the transcriptional changes in progesterone receptor(PR), total RNAs were extracted and applied to the semi-quantitative reverse transcription polymerase chain reaction(RT-PCR). As a result, delayed VO was shown in the DEHP group(PND $37.3{\pm}0.7$) compared to the control group(PND $35.3{\pm}0.7$; p<0.05). DEHP treatment significantly decreased the wet weight of ovaries and uteri compared to the control group(p<0.05). Interestingly, elevation of serum LH levels was shown in the DEHP group(p<0.05). Graafian follicles and corpora lutea were observed only in the ovaries from the control animals. Numerous primary, secondary follicles and small atretic follicles were observed in the ovaries from DEHP-treated animals. Similarly, hypotrophy of luminal and glandular uterine epithelium was found in the DEHP-treated group. These effects were probably due to the inhibitory effects of DEHP on the synthesis and secretion of estrogen from granulosa cells. In the semiquantitative RT-PCR studies, the transcriptional activities of PR in both ovary(p<0.05) and uterus(p<0.01) from DEHP-treated animals were significantly lower than those from the control animals. The present studies demonstrated that the acute exposure to DEHP during the critical period of prepubertal stage could inactivate the reproductive system resulting delayed puberty in female rats.

• Horticultural Science & Technology
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• v.30 no.5
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• pp.509-518
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• 2012

The objective of this study was to determine the effect of heat shock treatments on the phytochemicals including antioxidants and anticancer materials in kale (Brassica oleracea L. var. acephala) sprouts. In study I, kale sprouts grown under the growing system for four days were soaked at 40, 50, or $60^{\circ}C$ distilled water for 10, 30, or 60 seconds, and in study II, kale sprouts were soaked at $50^{\circ}C$ distilled water for 10, 20, 30, 45, or 60 seconds. After the heat shock treatments, the sprouts were transferred into normal growing conditions and recovered there for two days. Fresh and dry weights, electrolyte leakage, total phenolic concentration, antioxidant capacity, total flavonoid concentration, phenylalanine ammonia-lyase (PAL) activity, and glucosinolates content of the sprouts were measured before and after the heat shock treatments. As a result, there was a significant decrease in the fresh and dry weight of kale sprouts treated with heat shock compared with control at harvest in study I. Especially, heat shock at $60^{\circ}C$ lead to more pronounced growth inhibition compared with heat treatments at 40 and $50^{\circ}C$. Electrolyte leakage by cell collapse was the highest in the sprouts exposed to $60^{\circ}C$ distilled water, which agreed with the growth results. Heat shock at $50^{\circ}C$ significantly induced the accumulation of phenolic compounds. In study II, fresh weight of kale sprouts at $50^{\circ}C$ heat shock showed a significant decrease compared with the control at one and two days after the treatment. However, the decrease was minimal and dry weight of kale sprouts was not significantly different from that in control. In contrast, the heat shock-treated kale sprouts had higher level of total phenolic concentration than control at harvest. Heat shock treatments at $50^{\circ}C$ for 20 seconds or more showed at least 1.5 and 1.2 times higher total phenolic concentration and antioxidants capacity than control, respectively. The change of the total flavonoid concentration was similar with that of antioxidants. PAL activity after 24 hours of heat shock was higher in all the heat shock-treated sprouts than that in control suggesting heat shock may stimulate secondary metabolic pathway in kale sprouts. Seven glucosinolates were identified in kale sprouts and soaking the sprouts with $50^{\circ}C$ water for 20 seconds had a pronounced impact on the accumulation of total glucosinolates as well as two major glucosinolates, progoitrin and sinigrin, at harvest. In conclusion, this study suggests that heat shock using hot water would be a potential strategy to improve nutritional quality of kale sprouts by inducing the accumulation of phytochemicals with antioxidant and anticancer properties.

• Journal of Technology Innovation
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• v.25 no.2
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• pp.89-125
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• 2017

Complex product systems (CoPs) is a engineering-intensive products with high-ended design technology, which are closely linked with national economic growth and development of social infrastructures. Accordingly, in order to understand the technological evolution of CoPs, it is necessary to identify the macro-environmental drivers surrounding the CoPs and their impact on the technological evolution of the CoPS. Therefore, we investigate the effect of policy, economic and social drivers on the technological evolution of CoPS by implementing the longitudinal case study on nuclear power plant during the periods between 1950 and 2010s. Based on the analysis of various sources of secondary data and primary data through interviews, we found that the technological evolution of nuclear power plant is progressed as "Phase 1: Application research for peaceful utilization of nuclear energy" between 1950s and 1960s, "Phase 2: The first renaissance of nuclear energy" during 1970s, "Phase 3: Enhancement of safety and the catch-up of latecomers in nuclear energy" between 1990s and 2000s, and "Phase 4: Top prioritization of safety and the development of next generation reactors for the second renaissance of nuclear energy" since 2010s. We also found that various kinds of policy, economic and social drivers, such as energy policy, investment in technology development, economic growth and energy demand, social acceptability and environmental concern, have affected the technology evolution of nuclear power plant at each phase. We emphasize the role of macroenvironmental drivers in the technological evolution of CoPS. We also suggest that countries that endeavor to develop CoPs need to utilize those drivers for enhancing competitiveness and sustaining leadership.

• Korean Journal of Health Education and Promotion
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• v.16 no.2
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• pp.137-155
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• 1999

The purpose of this study was to assess the effect of sex education on knowledge and attitude related to sex. The subjects were taken from by 199 students in 3 classes from 1st grade in H girl's junior high school as the study group, and 2 classes from 1st grade in S girl's junior high school as control group. During the survey period(September 21, 1998 to September 30, 1998), 6 times in terms of one-hour class for sex education were taught to the study group. A pre-test was executed on September 19, 1998 and the post-test on September 30. The findings were as follows. 1. According to the research, 20.1％ of the subjects have experienced sex education from parents and 89.9％ from teacher. They have mostly obtained the sex-related information from teachers(59.8％), following movie, radio, TV, or video tape(40.7％), friends(35.2％), reading materials such as books, cartoons, news papers and magazines(31.7％), parents(15.6％), siblings(7.0％), PC(1.5％) and telephone service(1.5％). 2. 27.1％ of the subjects reported that they had sex-related worry concerning from friendship with the opposite sex, following physiological phenomenon(31.5％), sex violence(11.1％), physical characteristics(7.4％), VD and contraception(5.6％), sexual impulse(5.6％), pregnancy and delivery(5.5％), and sexual behaviour(3.7％). The research showed that the adolescents usually solved their problems through the consultation with theifriends(44.4％). However, 16.7％ of the subjects were turned out not to request any solution. The other minor routes to settle their problems were written materials such as books, magazines(13.0％), parents(13.0％), movie, radio, TV, or video tape(5.5％), acquainted female elders(3.7％) and teachers(3.7％). 3. The most interesting part regarding sex was the friendship with the opposite sex(61.8％), following adolescent's emotion(55.8％), physiological differences between two genders(52.8％), AIDS(48.7％), VD(46.7％), pregnancy(45.2％), contraception(45.2％), abortion(41.7％), intercourse(41.7％), masturbation(41.2％), sex violence(41.2％) and genital structure and secondary sexual characteristics(28.6％). 4. In regard to characteristics of the subjects influencing sex-related knowledge, the higher educational career of mother, living with at least either parent and the experience of sex education by teachers were statistically significant factors(p〈0.05). 5. In regard to characteristics of the subjects influencing attitudes toward sex, the experience of sex education by parents or teachers was a statistically significant factor(p〈0.05). 6. The analysis of knowledge score comparing results before and after sex education showed that control group's score decreased from 12.5 to 12.44 while the study group's score increased from 12.33 to 21.31, which was statistically significant(p〈0.001). 7. The analysis of the attitude scores before and after sex education showed that the control group's score slightly increased from 55.57 to 56.36, while the study group's score increased from 54.79 to 61.95, which was statistically significant(p〈0.001). 8. The level of sex-related concerns of the study group after sex education marked both the increase in some items and the decrease in others. 9. Most instructive session among the sex education was the third “to be a good friend to the opposite sex”(27.0％).

• Journal of The Korean Association For Science Education
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• v.32 no.4
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• pp.570-585
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• 2012

The Korean national curriculum for secondary school emphasizes scientific problem solving. In line with the national curriculum, many educational studies have been conducted in relation to science education. The objects of these studies were well-defined and well-structured problems. The studies were criticized for overlooking ill-defined and ill-structured problems. Some research has dealt with problem finding in ill-structured problems, which is related to creativity. There is a need for a study of scientific problem finding process in an ill-structured problem situation, because this study will help teachers wanting to teach scientific problem-finding in an ill-structured problem situation. The objective of this study was to conduct an empirical study on the scientific problem finding process in an ill-structured problem situation. One task of scientific problem finding in an ill-structured problem situation was assigned to 92 university students; thereafter, 32 of them participated in the research through interviews. Results indicated that the scientific problem finding process depended on initial clues and tentative solutions. Initial clues were affected by students' experiences, such as major classes, films, and novels. Tentative solutions were influenced by background knowledge of the tasks. Students screened information browsed on the Internet. They applied some standards for selection, particularly emphasized reliability standards, which are supposed to be studied in other contexts. All the students used assumptions to make their problems appear probable, which could be a useful tool to articulate.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.7
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• pp.1102-1107
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• 2003

To study the effects of substances in paeonia seeds (Paeonia lactiflora Pall.) on lipid metabolism, crude methanol extract and secondary ether-soluble fraction out of defatted methanol extract and trans-resveratrol were prepared from the seeds and added to 0.5% (w/w) cholesterol diets for rats. Male Sprague-Dawley rats weighing 120$\pm$11 g were divided into six experimental groups: control group with no extra supplement, 0.1% (MP1) and 0.2% methanol extract (MP2) supplemented groups, 0.05% (EP1) and 0.1% ether-soluble fraction (EP2) supplemented groups and 0.02% resveratrol supplemented group. Experimental diets were fed ad libitum to the rats for 3 weeks. Body weight gains and food efficiencies were not different among the six experimental groups. Relative liver weights were lower in EP2 group compared to those in control group, but serum GOT and GPT levels of paeonia seed groups including trans-resveratrol group were not different from those of the control group. Serum total cholesterol levels reduced in EP2 and resveratrol groups but HDL-/total cholesterol ratios significantly increased in the four paeonia groups except EP1 group compared with the control group and serum triglyceride level lowered only in EP2 group than that of the control. However, liver cholesterol levels lowered in the five paeonia groups but triglyceride level lowered in MP2, EP1, EP2 groups than that of the control group. Fecal cholesterol excretion significantly increased in MP2, EP1, and EP2 groups than that of the control group, but bile acid excretions were not changed except that a reduction in EP2 group. These results suggest that paeonia seeds contain substances improving serum lipid status mostly via HDL pathway and resveratrol as monomer is one of the effective components but others including resveratrol oligmer are involved in the lipid improving effect.

• Korean Journal of Remote Sensing
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• v.36 no.5_3
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• pp.1053-1066
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• 2020

Sulfur dioxide (SO₂) is primarily released through industrial, residential, and transportation activities, and creates secondary air pollutants through chemical reactions in the atmosphere. Long-term exposure to SO₂ can result in a negative effect on the human body causing respiratory or cardiovascular disease, which makes the effective and continuous monitoring of SO₂ crucial. In South Korea, SO₂ monitoring at ground stations has been performed, but this does not provide spatially continuous information of SO₂ concentrations. Thus, this research estimated spatially continuous ground-level SO₂ concentrations at 1 km resolution over South Korea through the synergistic use of satellite data and numerical models. A stacking ensemble approach, fusing multiple machine learning algorithms at two levels (i.e., base and meta), was adopted for ground-level SO₂ estimation using data from January 2015 to April 2019. Random forest and extreme gradient boosting were used as based models and multiple linear regression was adopted for the meta-model. The cross-validation results showed that the meta-model produced the improved performance by 25% compared to the base models, resulting in the correlation coefficient of 0.48 and root-mean-square-error of 0.0032 ppm. In addition, the temporal transferability of the approach was evaluated for one-year data which were not used in the model development. The spatial distribution of ground-level SO₂ concentrations based on the proposed model agreed with the general seasonality of SO₂ and the temporal patterns of emission sources.

• Journal of Preventive Medicine and Public Health
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• v.30 no.4 s.59
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• pp.741-751
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• 1997

Measurement of blood lead (PbB) and blood zinc protoporphyrin (ZPP) are most common biological indices to identify the individual at risk for excess or the health sequences by lead exposure. Because PbB is known most important and reliable index of lead exposure, PbB is often regarded as a gold standard to detect lead exposure. But in Korea PbB is a secondary test item of detailed health check-up with positive finding of screening test in most occasion. Our lead standard requires all lead workers to take annual heath-check twice a year for investigation of their health effect due to lead exposure. Blood ZPP is one of most important index to detect high lead absorption in lead workers as a screening test. Measurement of blood ZPP is known ,well to correlate with PbB in steady state of exposure in most lead workers and is often used as a primary screening test to detect high lead absorption of lead workers with the advantage of simplicity, easiness, portability and low cost. The current cut-off criteria of blood ZPP for further detailed health check-up is $100{\mu}g/d\ell$ which is supposed to match the level of $40{\mu}g/d\ell$ of PbB according to our standard. Authors tried to investigate the validity of current criteria of cut-off level $(100{\mu}g/d\ell)$ of blood ZPP and possible another better cut-off level of it to detect the lead workers whose PbB level over $40{\mu}g/d\ell$. The subjects in our study were 212 male workers in three small scale storage battery industries. Blood ZPP, PbB and hemoglobin (Hb) were selected as the indices of lead exposure. The results were as follows. 1. The mean of blood ZPP, PbB and Hb in lead workers were $79.5{\pm}46.7{\mu}g/d\ell,\;38.7{\pm}15.1{\mu}g/d\ell,\;and\;14.8{\pm}1.2g/d\ell$, respectively. There were significant differences in blood ZPP, PbB and Hb by industry (P<0.01). 2. The percents of lead workers whose blood ZPP were above $100{\mu}g/d\ell$ in the group of work duration below 1, 1-4, 5-9 and above 10 years were 8.6%, 17.2%, 47.6%, and 50.0%, respectively. The percents of lead workers whose PbB were above $40{\mu}g/d\ell$ in those were 31.4%, 40.4%, 71.4%, and 86.4%, respectively. 3. The percents of lead workers whose PbB were below $40{\mu}g/d\ell$, $40-59{\mu}g/d\ell$ and above $60{\mu}g/d\ell$ were 54.7%, 34.9% and 10.4%, respectively. Those of lead workers whose blood ZPP were below $100{\mu}g/d\ell$, $100-149{\mu}g/d\ell$ and above $150{\mu}g/d\ell$ were 79.2%, 13.7% and 7.1%, respectively. 4. Simple linear regression of PbB on blood ZPP was statistically significant (P<0.01) and as PbB was $40{\mu}g/d\ell$, blood ZPP was $82.1{\mu}g/d\ell$. 5. While the highest sensitivity and specificity of blood ZPP test to detect lead workers with PbB eve. $40{\mu}g/d\ell$ were observed in the cut-off level of $50{\mu}g/d\ell$ and $100{\mu}g/d\ell$ of blood ZPP, respectively, the highest validity (sensitivity+specificity) of blood ZPP to detect lead workers with PbB over $40{\mu}g/d\ell$ was observed in the cut-off level of around $70{\mu}g/d\ell$ of blood ZPP. But even with optimal cut-off level of around $70{\mu}g/d\ell$ of blood ZPP, still 25.0% of false negative and 20.7% false positive lead workers were found. As the result of this study, it was suggested that reconsideration of current blood ZPP cut-off of our lead standard from $100{\mu}g/d\ell$ to somewhat lower level such as around $70{\mu}g/d\ell$ and the inclusion of PbB measurement as a primary screening test for lead workers was highly recommended for the effective prevention of lead workers.

• Journal of Veterinary Clinics
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• v.31 no.5
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• pp.394-402
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• 2014

The objective of this study was to investigate the effect of chronic unpredictable stress on the reproductive function and ovarian luteinizing hormone receptor (LHR) expression. 9-week-old C57BL/6 female mice were randomly divided into two groups: control group and stressed group. Mice have been stressed twice a day for 35 days with 12 different stressors which were randomly selected. The results demonstrate that there is significant increase in the anxiety-related behaviors (P < 0.05), decrease body weight gain rate (P < 0.01) and decrease in the average of litter size in stressed mice compared with control group (P < 0.01). Furthermore, the rate of primary, secondary and early antral follicles in stressed mice significantly decreased (P < 0.05), whereas that of atretic follicles significantly increased compared with control mice (P < 0.01). The immunohistochemical analysis revealed that reduced LHR expression in granulosa cells of follicle and luteal cells of corpus luteum in response to chronic unpredictable stress. The western blot analysis revealed significantly decrease in LHR expression in the stressed mice ovaries compared with the control (P < 0.05). These results suggest that ovarian LHR expression affected by chronic unpredictable stress and the modulated ovarian LHR is responsible for ovarian follicular maldevelopment and reproductive dysfunction.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.100-101
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• 2012

The plasma damage free and room temperature processedthin film deposition technology is essential for realization of various next generation organic microelectronic devices such as flexible AMOLED display, flexible OLED lighting, and organic photovoltaic cells because characteristics of fragile organic materials in the plasma process and low glass transition temperatures (Tg) of polymer substrate. In case of directly deposition of metal oxide thin films (including transparent conductive oxide (TCO) and amorphous oxide semiconductor (AOS)) on the organic layers, plasma damages against to the organic materials is fatal. This damage is believed to be originated mainly from high energy energetic particles during the sputtering process such as negative oxygen ions, reflected neutrals by reflection of plasma background gas at the target surface, sputtered atoms, bulk plasma ions, and secondary electrons. To solve this problem, we developed the NBAS (Neutral Beam Assisted Sputtering) process as a plasma damage free and room temperature processed sputtering technology. As a result, electro-optical properties of NBAS processed ITO thin film showed resistivity of $4.0{\times}10^{-4}{\Omega}{\cdot}m$ and high transmittance (>90% at 550 nm) with nano- crystalline structure at room temperature process. Furthermore, in the experiment result of directly deposition of TCO top anode on the inverted structure OLED cell, it is verified that NBAS TCO deposition process does not damages to the underlying organic layers. In case of deposition of transparent conductive oxide (TCO) thin film on the plastic polymer substrate, the room temperature processed sputtering coating of high quality TCO thin film is required. During the sputtering process with higher density plasma, the energetic particles contribute self supplying of activation & crystallization energy without any additional heating and post-annealing and forminga high quality TCO thin film. However, negative oxygen ions which generated from sputteringtarget surface by electron attachment are accelerated to high energy by induced cathode self-bias. Thus the high energy negative oxygen ions can lead to critical physical bombardment damages to forming oxide thin film and this effect does not recover in room temperature process without post thermal annealing. To salve the inherent limitation of plasma sputtering, we have been developed the Magnetic Field Shielded Sputtering (MFSS) process as the high quality oxide thin film deposition process at room temperature. The MFSS process is effectively eliminate or suppress the negative oxygen ions bombardment damage by the plasma limiter which composed permanent magnet array. As a result, electro-optical properties of MFSS processed ITO thin film (resistivity $3.9{\times}10^{-4}{\Omega}{\cdot}cm$, transmittance 95% at 550 nm) have approachedthose of a high temperature DC magnetron sputtering (DMS) ITO thin film were. Also, AOS (a-IGZO) TFTs fabricated by MFSS process without higher temperature post annealing showed very comparable electrical performance with those by DMS process with $400^{\circ}C$ post annealing. They are important to note that the bombardment of a negative oxygen ion which is accelerated by dc self-bias during rf sputtering could degrade the electrical performance of ITO electrodes and a-IGZO TFTs. Finally, we found that reduction of damage from the high energy negative oxygen ions bombardment drives improvement of crystalline structure in the ITO thin film and suppression of the sub-gab states in a-IGZO semiconductor thin film. For realization of organic flexible electronic devices based on plastic substrates, gas barrier coatings are required to prevent the permeation of water and oxygen because organic materials are highly susceptible to water and oxygen. In particular, high efficiency flexible AMOLEDs needs an extremely low water vapor transition rate (WVTR) of $1{\times}10^{-6}gm^{-2}day^{-1}$. The key factor in high quality inorganic gas barrier formation for achieving the very low WVTR required (under ${\sim}10^{-6}gm^{-2}day^{-1}$) is the suppression of nano-sized defect sites and gas diffusion pathways among the grain boundaries. For formation of high quality single inorganic gas barrier layer, we developed high density nano-structured Al2O3 single gas barrier layer usinga NBAS process. The NBAS process can continuously change crystalline structures from an amorphous phase to a nano- crystalline phase with various grain sizes in a single inorganic thin film. As a result, the water vapor transmission rates (WVTR) of the NBAS processed $Al_2O_3$ gas barrier film have improved order of magnitude compared with that of conventional $Al_2O_3$ layers made by the RF magnetron sputteringprocess under the same sputtering conditions; the WVTR of the NBAS processed $Al_2O_3$ gas barrier film was about $5{\times}10^{-6}g/m^2/day$ by just single layer.