• 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.

• Journal of Surface Science and Engineering
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• v.29 no.6
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• pp.739-744
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• 1996

Lanthanide diphthalocyanines have interesting properties on electrochemical and chemical redox reactions. It is however, difficult to use because of thier short device life. Plasma-polymerization attends to improvement thier device life. Yb-diphthalocyanine ($YbPc_2$) polymer film was deposited in a parallel plate electrodes-type RF plasma reactor. $YbPc_2$ was sublimed into the argon plasma, and polymer film was obtained on a substrate. Radio frequency was constant of 13.56MHz. Pressure of argon gas, sublimation rate of $YbPc_2$ and RF power were variable parameters depending on film quality. Surface of polymer films include a lot of sub-micron order lumps. It was indicated that size of lumps depends on polymerization degree controled by parameters. Size of lumps and polymerization degree are increased with RF power. However, by the high RF power over 40W, polymerization degree is decreased with RF power and surface of film is rough. In condition of RF power is high, polymerization will compete with etching of film. We obtained good films for electrochromic display with RF power of 20W, argon gas pressure of 8.0 Pa and sublimationrate of $1.2 \times 10$ mol/min, and good films for gas sensor with RF power of 30W, argon gas pressure of 10.6Pa and sublimation rate of $1.2 \times 10$ mol/min.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.4
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• pp.605-610
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• 2001

To suppress the gas forming caused by some yeast in the pack of traditional kochujang prepared at Sunchang area, which is the most severe problem during distribution of commercial products, mustard or horseradish powder as natural preservatives was mixed to the ingredients of kochujang and left for fermentation in clay pot as commercial scale for 180 day. The composition changes including quality and gas formaing in the kochujang containing those additives were monitored physicochemically and organoleptically. The fermented kochujang containing those additives were monitored physicohemically and organoleptically. The fermented kochujang containing 0.6% of horseradish showed lower organic acid content than that of the control but amino type nitrogen content, which is one of the important quality reference of kochujang, was higher in the one containing 0.6% natural preservatives. No color changed in the kochujang containing mustard but L and a value were increased in the kochujang containing horseradish. No difference of free reducing sugars was showed by the addition of those natural preservatives and the addition of 0.6% horseradish to kochujang had completely stopped gas forming during fermentation. The overall quality of the kochujang containing 0.6% horseradish was superior than that of the other treatments.

• Economic and Environmental Geology
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• v.46 no.4
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• pp.351-358
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• 2013

Methane burns more clearly than any other fossil fuels. Coalbed methane(CBM) is natural gas contained in coal beds. This gas is usually producted from coal that is either too deep or too poor-quality to be mined commercially. While global coalbed methane resource estimates are rough, they indicate between 84 and 377tcm, which compares with proven natural gas reserves of 180tcm. Coalbed methane resources are currently only produced on a major scale in the United States, Canada, Australia and China. In this study, we analysed total 109 published papers for the CBM during the 1990~2012 periods by the programs of 'web of science'. The results of analysis, the CBM study led by the United States, the follow India and Australia. In subject area(web of sciences), Energy Fuels is 57, Engineering 58 and Geology 41 papers, respectively.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.8
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• pp.1208-1214
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• 2007

Three male Gayal, two years of age and with a mean live weight of $203{\pm}26$ kg, and three adult Yunnan Yellow Cattle, with a mean live weight of $338{\pm}18$ kg were fed a ration of pelleted lucerne hay and used to collect rumen fluid for in vitro measurements of digestibilities and gas production from fermentation of a range of forages. The forages were: bamboo stems, bamboo twigs, bamboo leaves, rice straw, barley straw, annual ryegrass hay, smooth vetch hay and pelleted lucerne hay. There were significant (p<0.05) effects of the source of rumen fluid on in vitro dry matter digestibility (IVDMD) and gas production during fermentation of forage. For the roughage of lowest quality (bamboo stems and rice straw), gas production during fermentation was higher (p<0.05) in the presence of rumen fluid from Gayal than Yunnan Yellow Cattle. Differences for these parameters were found for the better quality roughages with gas production being enhanced in the presence of rumen fluid from Yunnan Yellow Cattle. Moreover, the IVDMD of investigated roughages was significantly higher (p<0.05) in Gayal than Yunnan Yellow Cattle. The results offer an explanation for the positive live weight gains recorded for Gayal foraging in their natural environment where the normal diet consists of poor quality roughages.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.12
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• pp.1594-1600
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• 2010

A study was conducted to determine the dietary effects of a clay mineral (sodium bentonite, NaB) on manure gas emission, health, production, and meat characteristics of Hanwoo steers. Two diets fed to steers included a control diet (concentrate mix and rice straw) and a treatment diet (control diet+1.0% clay mineral/concentrate mix). Dietary NaB addition considerably reduced concentrations of gases ($H_2S$, $SO_2$ and $NH_3$) in the manure of Hanwoo steers. Growing steers fed NaB had similar blood profiles with the exception of lower (p<0.05) concentrations of blood alkaline phosphatase and lactate dehydrogenase. Dietary NaB addition tended to increase (p = 0.10) live weight by 30 kg at slaughtering and did not affect carcass yield and quality traits. Dietary NaB addition increased concentrations of P (p<0.01), Mg (p<0.01), Na (p<0.01), Zn (p<0.005), K (p = 0.08), Fe (p = 0.08) and Cu (p = 0.07) in the longissimus muscle compared to the control but did not affect (p>0.05) fatty acid composition. The study demonstrated that the dietary addition of a clay mineral could be effective in improving mineral bioavailability to Hanwoo steers, which could be one of the reasons for their improved performance.

• Korean Chemical Engineering Research
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• v.62 no.1
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• pp.70-79
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• 2024

Raman analyzer is an analytical technique that utilizes the "Raman effect", which occurs when light is scattered by the inherent vibrations of molecules. It is used for molecular identification and composition analysis. In the natural gas industry, it is widely used in bunkering and tank lorry fields in addition to LNG export and import terminals. In this study, a LNG-specific Raman analyzer was installed and operated under actual field conditions to analyze the composition and principal properties (calorific value, reference density, etc.) of LNG. The measured LNG composition and calorific value were compared with those obtained by conventional gas chromatograph that are currently in operation and validated. The test results showed that the Raman analyzer provided rapid and stable measurements of LNG composition and calorific value. When comparing the calorific value, which serves as the basis for LNG transactions, with the results from conventional gas chromatograph, the Raman analyzer met the acceptable error criteria. Furthermore, the measurement results obtained in this study satisfied the accuracy criteria of relevant international standards (ASTM D7940-14) and demonstrated similar outcomes compared to large-scale international demonstration cases.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.99-108
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• 2018

An oil-tolerant and salt-resistant aqueous foam system was screened out as a possible lubricant to enable cold heavy oil transportation. The microstructures and viscoelasticity and effects of heavy oil, salt and temperature on the foam stability were investigated and new rheological and drainage models were established. The results indicate the foam with multilayered shells belongs to a special microcellular foam. The viscoelasticity could be neglected due to its low relaxation time. The drainage process can be divided into three stages. The foam with quality of 67.9% maintains great stability at high oil and salt concentrations and appropriate elevated temperature.

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.4
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• pp.408-421
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• 2016

Day and night sampling for gas and particle phases PAHs were carried out in Seoul to characterize gas and particle phases PAHs concentrations in day and night times. There was no significant difference between day and night time for particle phase PAHs concentrations and phase distribution of PAHs, while, gas phase PAHs concentrations in daytime were about 1/2 of nighttime concentrations in both summer and winter due to photochemical reaction of gas phase PAHs during daytime. A high fraction of cancer risk for PAHs was attributed to particle phase PAHs and the excess cancer risk in winter was higher than in summer. The excess cancer risk level of total(gas+particle) PAHs in summer was partially observed when both gas and particle phase PAHs concentrations were considered as risk assessment. Based on the diagnostic ratios and factor analysis of PAHs concentrations, combustion(coal and natural gas) and vehicular emission might be the most significant contributors of PAHs and major factors for determining of PAHs concentration were different between day and night times.

• Journal of the Korean Institute of Educational Facilities
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• v.11 no.2
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• pp.17-23
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• 2004

The purpose of this study concerns the improvement of air quality in school classrooms. Polluted indoor air is improved by efficient ventilation systems. So it is important to measure the amount of ventilation needed in classrooms. First, the amount of natural ventilation were measured through a tracer gas method. And we have established a heat recovery ventilation system from 4 cases of airflow in classrooms, and we have measured the change of $CO_2$ density. According to air quality measurements in the classrooms, the density of $CO_2$ is well above environmental standards which are acceptable. When the amount of ventilated airflow increases, indoor air quality is improved. It is surveyed that the most suitable amount of external inducted air is 770 CMH to satisfy $CO_2$ less than 1,000 ppm in classrooms. For improvement of air quality in classrooms, we must consider a suitable ventilation plan and installation of ventilation systems when constructing school buildings.