• Applied Chemistry for Engineering
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• v.10 no.4
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• pp.497-501
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• 1999

The changes of properties were studied for the polypropylene(PP)/Nylon6 blends containing different kinds of compatibilizer made by either reactive extrusion of solution reaction. The compatibilizers were PP grafted with maleic anhydride (MAH) made by reactive extrusion and solution reaction. The grafted MAH contents were 0.3 wt %, and 2.7 wt %, respectively. The composition of the PP/nylon6 blend was fixed at 75/25 by weight. Blending was carried out with twin-screw extruder (L/D=30, ${\psi}=30$) at 300 rpm. As the content of PP-g-MAH was increased, the crystallization peak of Nylon6 decreased gradually then finally disappeared. Disappearance of crystallization peak of Nylon6 was mostly affected by grafted MAH content rather than the preparation method and the amount of compatibilizer. The portion of Nylon6 that could not crystallize in its normal crystallization temperature crystallized together with PP at the crystallization temperature of PP. So called concurrent crystallization was observed. Meanwhile two more peaks were observed during heating cycle. One was exothermic peak at $193^{\circ}C$ near to crystallization temperature of Nylon6, the other was endothermic peak at $215^{\circ}C$ that was $5^{\circ}C$ lower than normal endothermic peak of Nylon6. To analyze the peaks, nylon6 was annealed in the differential scanning calorimeter. As a result, the peak at $193^{\circ}C$ was crystallization peak of imperfect crystalline of Nylon6 and the other peak at $215^{\circ}C$ was melting peak of imperfect crystalline of nylon6.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.26 no.2
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• pp.77-83
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• 2020

A series of foamed plastic sheets containing biomass (as HMR container) were developed via different foaming process temperatures, and their density, porosity, WVTR, and pore morphology were evaluated. Thermal stability of samples during re-heating the food in oven, change in morphology, density, porosity, and WVTR were investigated using a simulated thermal shock process according to MIL-STD-883E assay. As such, the pore size of samples was generally increased with increasing temperature of the foaming process. It can be explained that as foaming temperature increased, the viscosity of molten resins and the repulsive force against pore expansion decreased. In addition, an increase in the thermal shock cycle reduced the pore size and WVTR, while density increased because high temperature treatment that softened the sheet matrix was followed by a low temperature incubation, which contracted the matrix, thereby changing the physical and morphological properties of samples. However, an insignificant change in density was observed and WVTR tended to be decreased, indicating that as-prepared foamed plastic sheets could be used as a high thermal stable container for HMR application. Therefore, it found that the properties of newly developed HMR containers containing biomass were dependent on the foaming process temperature. Moreover, to better understanding of these newly developed containers, further investigations dealing with foaming process temperature based on various food items and cooking conditions are needed.

• Tunnel and Underground Space
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• v.21 no.6
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• pp.518-525
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• 2011

In this study, the natural ventilation pressure resulting from the large altitude difference which is a characteristic of high radioactive waste repository and the caloric value of the heat emitted by wastes was calculated and based on the results, natural ventilation quantities were calculated. A high radioactive waste repository can be considered as being operated through closed cycle thermodynamic processes similar to those of thermal engines. The heat produced by the heating of high radioactive wastes in the underground repository is added to the surrounding air, and the air goes up through the upcast vertical shaft due to the added heat while working on its surroundings. Part of the heat added by the work done by the air can be temporarily changed into mechanical energy to promote the air flow. Therefore, if a sustained and powerful heat source exists in the repository, the heat source will naturally enable continued cyclic flows of air. Based on this assumption, the quantity of natural ventilation made during the disposal of high radioactive wastes in a deep geological layer was mathematically calculated and based on the results, natural ventilation pressure of $74{\sim}183$Pa made by the stack effect was identified along with the resultant natural ventilation quantity of $92.5{\sim}147.7m^3/s$. The result of an analysis by CFD was $82{\sim}143m^3/s$ which was very similar to the results obtained by the mathematical method.

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.612-618
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• 1999

Physicochemical properties of amaranth starch were compared with those of waxy rice and waxy corn starches. Amaranth starch granules vary from $1.1{\sim}1.9\;{\mu}m$ in diameter and are polygonal in shape. Total amylose contents from waxy rice, waxy corn and amaranth starches were 0.01, 0.03 and 0.07%, respectively. Swelling power of amaranth starch granule was slightly different from waxy rice. The swelling power of amaranth increased at $70^{\circ}C$. X-ray diffraction patterns of amaranth and other waxy cereal starches showed an A-type crystalline structure. Relative crystallinities of their starches were similar. According to pasting properties by Rapid Visco-Analyzer, amaranth starch showed a very high gelatinization temperature $(75.1^{\circ}C)$ and lower viscosity and higher stability than other waxy cereal starches during heating and cooling cycle. Peak onset temperatures (To) of starches from waxy rice, waxy corn and amaranth in DSC thermograms were $58.7{\sim}64.0$, 67.2 and $71.5^{\circ}C$, respectively, and their peak enthalpies were similar. Enthalpy of reheated amaranth starch after 3 day storage at $4^{\circ}C$ was higher than those of waxy corn and rices starchs.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.10 no.4
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• pp.247-254
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• 2012

Vitrification technology has been widely applied as one of effective processing methods for wastes generated in nuclear power plants. The advantage of vitrifying for low- and intermediate-level radioactive wastes has a large volume reduction and good durability for the final products. Recently, a filter using on HVAC(Heating Ventilating & Air Conditioning System) is composed with media (glass fiber) and separator (aluminum film) has been studied the proper treatment technology for meeting the waste disposal requirement. Present paper is a feasibility study for the filter vitrification that developing of the glass compositions for filter melting and melting test for physicochemical characteristic evaluation. The aluminum metal of film type is preparing with 0.5 cm size for proper mixing with glass frit, glass fiber is also preparing with 1 cm size within crucible. The glass compositions should be developed considering molten glass are related with wastes reduction. Glass compositions obtained from developing on glass formulation are mainly composed of $SiO_2$ and $B_2O_3$ for aluminum metal. A variety of factors obtained from the glass formulation and melting test are reviewed, which is feeding rate and glass characteristics of final products such as durability for implementing the wastes disposal requirement.

• Korean Journal of Food Science and Technology
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• v.30 no.3
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• pp.615-623
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• 1998

The garlic juices were extracted and concentrated by heating at $90^{\circ}C$, by using a rotary vacuum evaporator at $45^{\circ}C$, or by freezing at $-50^{\circ}C$ until the volume was reduced to 70% of the original volume. The concentrated juices were kept at $4^{\circ}C\;or\;25^{\circ}C$ for 60 days and the changes of bacteria and color were monitored every 10 days. Flavors of the raw garlic juices, concentrated garlic juices, and garlic powder by hot-air drying were analyzed monthly using GC and GC/MS. The CFUs/mL of mesophilic and psychrotrophic bacteria in the garlic juice concentrated at $90^{\circ}C$ were lower about 1 to 2 log cycles than those of other concentrated juices. Hunter L, a, and b values in the raw garlic raw juice and the juice concentrated at $-50^{\circ}C$ significantly increased at the beginning of storage, in particular, when they were stored at $25^{\circ}C$. The garlic juice concentrated at $45^{\circ}C$ showed relatively low L value but the juice concentrated at $90^{\circ}C$ showed high a value. The main peaks in chromatograms of volatile components identified by GC/MS were 3,3'-thiobis-1-propene, di-2-propenyl disulfide, 3-(methylthio)-1-propene in the raw garlic juice and the concentrated juices, and the juices concentrated at $45^{\circ}C\;or\;-50^{\circ}C$ showed relatively high preservation of garlic flavor.

• Journal of Digital Convergence
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• v.8 no.1
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• pp.109-120
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• 2010

Mobile phone-related industries have been mainly concentrated on attracting the new customers and increasing the market share such as for the aggressive marketing activities, but it is the time to find an effective strategy to preserve existing customers since the mobile phone market had already reached the saturation. In this study, the properties of mobile phone that influence on the choice of handset and telecom company were analyzed. General properties of respondents were explored and the mobile phone properties were grouped by common factors. And analyzed the effect of factors on customer satisfaction with structural equation model. 10.4% of respondents are used their handset more than two years and 48.7% wanted to purchase other manufacturer's handset if they repurchase mobile phone. These results might come form the fact that the life cycle of mobile phone become shorter by the heating competition in mobile phone market and, to some degree, the influence of smart phone which recently become globally popular. Four factors, 'Hardware Quality', 'Practicality', 'Convergence Functions' and 'Level of Awareness', are induced from the mobile phone properties. In Structural Equation Model analysis, 'Hardware Quality' and 'Practicality' have significant and positive effects on Customer Satisfaction. But, 'Awareness' such as brand and trend appeared quite less influence on the customer satisfaction.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.6
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• pp.1095-1101
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• 2001

Spinach was minimally processed into the unseasoned side dish to be used for Korean food service industry, using the techniques of cook-chill and sous vide. Spinach was blanched at 10$0^{\circ}C$ for 6 minutes, vacuum-packaged in the unit of 500 g by plastic film of low gas permeability, pasteurized at 9$0^{\circ}C$ and then cooled rapidly at 3$^{\circ}C$. The chilled products were then stored at 3 and 1$0^{\circ}C$ with measurement in their quality. Six log cycle (6D) inactivation of Listeria monocytogenes and 13 log (13D) thermal destruction of Streptococcus faecalis were compared as two pasteurization conditions, which corresponded to heating for 22.8 and 30.0 minutes at 9$0^{\circ}C$, respectively. Milder heat processing based on 6D process of L monocytogenes gave better quality of color, texture, ascorbic acid and chlorophyll than the conditions of 13D process of S. faecalis. Any microbial growth in total aerobic, psychrophilic and anaerobic bacteria was not observed until 8 days at 1$0^{\circ}C$ and 14 days at 3$^{\circ}C$, which might be regarded as strict guidelines of shelf life. Storage times based on the changes in physical and chemical quality were longer than those based on strict microbial quality in case of the products pasteurized by 6D process of L. monocytogenes. The seasoned vegetables prepared from sous vide processed spinach were found to be inferior in sensory quality to those from freshly blanched one.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.2
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• pp.243-260
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• 2018

A literature review on the effects of high temperature and radiation on radiation shielding concrete in Spent Fuel Dry Storage is presented in this study with a focus on concrete degradation. The general threshold is $95^{\circ}C$ for preventing long-term degradation from high temperature, and it is suggested that the temperature gradient should be less than $60^{\circ}C$ to avoid crack generation in concrete structures. The amount of damage depends on the characteristics of the concrete mixture, and increases with the temperature and exposure time. The tensile strength of concrete is more susceptible than the compressive strength to degradation due to high temperature. Nuclear heating from radiation can be neglected under an incident energy flux density of $10^{10}MeV{\cdot}cm^{-2}{\cdot}s^{-1}$. Neutron radiation of >$10^{19}n{\cdot}cm^{-2}$ or an integrated dose of gamma radiation exceeding $10^{10}$ rads can cause a reduction in the compressive and tensile strengths and the elastic moduli. When concrete is highly irradiated, changes in the mechanical properties are primarily caused by variation in water content resulting from high temperature, volume expansion, and crack generation. It is necessary to fully utilize previous research for effective technology development and licensing of a Korean dry storage system. This study can serve as important baseline data for developing domestic technology with regard to concrete casks of an SF (Spent Fuel) dry storage system.

• Journal of the Mineralogical Society of Korea
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• v.32 no.3
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• pp.201-211
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• 2019

The particle size and crystallinity of fault gouge generally decreases with slip. Phyllosilicates including talc are known to be present in fault gouge and play an important role in fault weakening. In particular, the coefficient of friction varies depending on the presence of a water molecule on the surface of mineral. The purpose of this study is to investigate the effect of talc on fault weakening by changing the water content and dehydration behavior of talc before and after grinding, which systematically varied particle size and crystallinity using high energy ball mill. Infrared spectroscopy and thermal analysis show that the as-received talc is hydrophobic before grinding and the water molecule is rarely present. After grinding up to 720 minutes, the particle size decreased to around 100 ~300 nm, and in talc, where amorphization proceeded, the water content increased by about 8 wt.% and water molecule would be attached on the surface of talc. As a result, the amount of vaporized water by heating increased after grinding. The dihydroxylation temperature also decreased by ${\sim}750^{\circ}C$ after 720 minutes of grinding at ${\sim}950^{\circ}C$ before grinding due to the decrease of particle size and crystallinity. These results indicate that the hydrophobicity of talc is changed to hydrophilic by grinding, and water molecules attached on the surface, which is thought to lower the coefficient of friction of phyllosilicates. The repeated slip throughout the seismic cycle would consistently lower the coefficient of friction of talc present in fault gouge, which could provide the clue to the weakening of matured fault.