• Polymer(Korea)
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• v.30 no.3
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• pp.259-265
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• 2006

Small intestinal submucosa (SIS) consists of some growth factors which can stimulate cell activity, and PVA has been widely utilized in the area of wound dressing as hydrogel which is easy to be removed from wounds. In this study, native SIS sheets were coated with PVA by immersing them into 2, 4, and 10 wt% of PVA solution and then lyophilized on two type of molds to endow the prepared wound dressing with easy removal property from wounds. The mechanical properties were examined through tensile test. Moreover, enzymatic degradation, water uptake, and in vitro test were carried out to characterize the prepared SIS sheets. The tensile strength of the SIS sheets coated with PVA (PVA-SIS) were decreased, whereas the elongation were increased. Degradation ratio of the PVA-SIS sheets was decreased compare to native SIS. Water uptake ability was improved at 2 and 4 wt% of PVA. The degree of fibroblast attachment was lower than the native SIS sheets. In conclusion, this study suggests that the PVA coated SIS sheets have a potential for the applications of wound dressing and biodegradable injectable materials.

• Korean Journal of Materials Research
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• v.30 no.1
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• pp.38-43
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• 2020

Sand casting 3D printing uses a binder jetting method to produce a mold having complicated shape by spraying a binder on sand coated with activator. Appropriate heat treatment process in sand mold fabrication can increase the degree of polymerization to improve flexural strength. However, long heat treatment of over 24 hours decreases flexural strength and reliability due to chemical bond decomposition through thermal degradation. The main role of the activator is to control the reaction rate between the polymer chains. As a result, when the activator composition is increased from 0.15 wt% to 0.25 wt%, the flexural strength is increased by 218 N/㎠. However, excess activator (0.40 wt%) has been shown to decrease reliability without increasing flexural strength. The main role of the binder is to control the flexural strength of the specimen. As the binder composition is increased from 2.00 wt% to 4.00 wt%, the flexural strength increases to about 255 N/㎠, indicating the maximum flexural strength increase. Finally, the reliability of the flexural strength of the fabricated specimens is evaluated by a Weibull plot. Weibull modulus calculations are used to evaluate the flexural strength reliability of the specimens, and maximum reliability value of 11.7 is obtained at 0.20 wt% activator composition. Therefore, it is confirmed that this composition has maximum flexural strength reliability.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.12
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• pp.609-619
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• 2015

A preprocessing scheme utilizing multi-division of the ROI (region of interest) in a chemiluminescence image during inversion is proposed. The resulting inverted image shows the flame's structure, which can be useful for studying combustion instability. The flame structure is often quantitatively visualized with PLIF (planar laser-induced fluorescence) images as well. The chemiluminescence image, which is a line-integral of the flame, needs to be preprocessed before inversion, mainly due to the inherent noise and the assumption of axisymmetry during the inversion. The feasibility of the multi-division preprocessing technique has been tested with experimentally-obtained OH PLIF and $OH^*$ chemiluminescence images of jet and swirl-stabilized flames burning substitute natural gas (SNG). It turns out that the technique outperforms two conventional methods, specifically, the technique without preprocessing and the one with uni-division, reconstructing the SNG flame structures much better than its two counterparts when compared using corresponding OH PLIF images. The characteristics of the optimum degree of polynomials to be applied for curve-fitting of the flame region data for the multi-division method involving two flames has also been investigated.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.5
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• pp.197-202
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• 2001

The influence of thermal treatment and cold drawing was investigated for poly(ethy1ene terephthalate) films fabricated with various experimental conditions. Samples were elongated at room temperature under stepwise-drawing condition with the cross-head speed kom 0.5 to 500 mrdmin in an universal tester. Stress oscillation was observed in the stress-stnin curve of the samples heat-treatd at 50, 72 and $129^{\circ}C$ for 30 min, but it was not observed in the samples heat-treatd at $83^{\circ}C$ for 30 min. Thermal analyses of the samples were carried out in differential scanning calorimeter at the heating rate df $10^{\circ}C$/min/min, and the glass transition temperature, crystallization peak, enthalpy of fusion and degree of crystallinity were measured. The dynamic mechanical analyses of the samples were also carried out in a multiplefimction internal kiction pendulum at 1 Hz with the heating rate of $1.5^{\circ}C$/min, and it was found that the elastic modulus increases in the order of non-treated, heat-treated, and elongated samples.

• Environmental Engineering Research
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• v.11 no.4
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• pp.217-231
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• 2006

The gas-phase formation of polychlorinated naphthalenes (PCNs) and dibenzofurans (PCDFs) was experimentally investigated by slow combustion of the three chlorophenols (CPs): 2-chlorophenol (2-CP), 3-chlorophenol (3-CP) and 4-chlorophenol (4-CP), in a laminar flow reactor over the range of 550 to $750^{\circ}C$ under oxidative condition. Contrary to the a priori hypothesis, different distributions of PCN isomers were produced from each CP. To explain the distributions of polychlorinated dibenzofuran (PCDF) and PCN congeners, a pathway is proposed that builds on published mechanisms of PCDF formation from chlorinated phenols and naphthalene formation from dihydrofulvalene. This pathway involves phenoxy radical coupling at unsubstituted ortho-carbon sites followed by CO elimination to produce dichloro-9, 10-dihydrofulvalene intermediates. Naphthalene products are formed by loss of H and/or Cl atoms and rearrangement. The degree of chlorination of naphthalene and dibenzofuran products decreased as temperature increased, and, on average, the naphthalene congeners were less chlorinated than the dibenzofuran congeners. PCDF isomers were found to be weakly dependent to temperature, suggesting that phenoxy radical coupling is a low activation energy process. Different PCN isomers, on the other hand, are formed by alternative fusion routes from the same phenoxy radical coupling intermediate. PCN isomer distributions were found to be more temperature sensitive, with selectivity to particular isomers decreasing with increasing temperature.

• Journal of Convergence for Information Technology
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• v.8 no.2
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• pp.227-232
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• 2018

The purpose of this study is to investigate the relationship between facial image efficacy and job satisfaction in a sample of 167 workers in SMEs in Seoul and Gyeonggi province. and to examine the effect of SME workers' face image efficacy on job satisfaction. The results of the study are as follows. First, there was a statistically significant correlation between management ability and job satisfaction, which is a sub - area of facial image efficacy. This means that the higher the management ability, the higher the degree of job satisfaction. There was a statistically significant correlation between perception attitude and job satisfaction, which is a sub - area of face image efficacy. Second, management ability, which is a sub - area of face image efficacy of SME workers, has a statistically significant effect on job satisfaction. The sub - domain of face image efficacy has no effect on job satisfaction, Expression confidence, which is a sub-domain of image efficacy, has a statistically significant effect on job satisfaction.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.6
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• pp.252-255
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• 2014

Indium tin oxide (ITO) films with various oxygen partial pressure from 0 to $6{\times}10^{-5}$ Pa were prepared onto polyethylene terephthalate (PET) using RF magnetron sputtering at room temperature. The structural, electrical and optical properties of the grown ITO films were investigated as a function of the oxygen partial pressure. The amorphous nature of the ITO films was dominant at the partial pressure below $1{\times}10^{-5}$ Pa and the degree of crystallinity increased as the oxygen concentration increased further. This structural change comes with the increased carrier concentration and reduction of the electrical resistivity down to $9.8{\times}10^{-4}{\Omega}{\cdot}cm$. The average transmittance (at 400~800 nm) of the ITO deposited on the PET substrates increased as the oxygen partial pressure increased and transmittance above 80 % was achieved with the partial pressure of $4{\times}10^{-5}$ Pa. The results show that the choice of optimal oxygen partial pressure can present improved film crystallinity, the increased carrier concentration, and the enhancement in the electrical conductivity.

• Journal of Environmental Health Sciences
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• v.36 no.3
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• pp.229-235
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• 2010

Efforts to evaluate water pollution using indicator microorganisms have been underway for decades, and driven by research on water purity control applications, water quality criteria are growing more and more strict. Furthermore, recent reports indicate that high concentrations of antibiotics are not absorbed, and are present in excrement from animals and humans dosed with unnecessarily high levels of antibiotics. This has emerged as very important issue from the standpoint of being an ecological and health hazard. In this study, water pollution was analyzed through physicochemical and microbiological means, and antibiotic resistance in indicator microorganisms was assessed. In physicochemical analysis, biochemical oxygen demand (BOD)$_5$ and chemical oxygen demand (COD)$_{Mn}$ evaluation showed that pollution by organisms was highest at the G1 location with a high human population, and the DP location which has many livestock-containing households. The indicator organism levels at the G1 location were: Total Coliforms (1205 colony forming units (CFU)/100 ml), Fecal Coliforms (270 CFU/100 ml), Escherichia coli (253 CFU/100 ml) and Fecal Streptococci (210 CFU/100 ml), while for the DP location levels were: Total Coliforms (1480 CFU/100 ml), Fecal Coliforms (438 CFU/100 ml), E. coli (560 CFU/100 ml), and Fecal Streptococci (348 CFU/100 ml). Levels of fecal indicator microorganisms such as Fecal Coliforms, E. coli and Fecal Streptococci were high at all locations in the fall (the period after the rainy season), and the yearly distribution was similar between these organisms. If the number of livestock-containing households was high, almost all strains of E. coli (as distinct from the other indicator organisms) showed resistance to antibiotics, with the degree of resistance varying between areas. E. coli strains from the OY area in particular, which has a high population density, showed strong resistance to AM10 and Va30. While strong antibiotic resistance was observed overall at the DP and OY locations, no resistance was observed at the EB location.

• Journal of Intelligence and Information Systems
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• v.14 no.1
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• pp.35-45
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• 2008

In order to constructan ubiquitous computing environment, it is necessary to develop a technology that can recognize users and circumstances. In this regard, the question of recognizing and expressing user Context regardless of computer and language types has emerged as an important task under the heterogeneous distributed processing system. As a means to solve this task of representing user Context in the ubiquitous environment, this paper proposes to describe user Context as the most similar form of human thinking by using semantic web and fuzzy concept independentof language and computer types. Because the conventional method of representing Context using an usual collection has some limitations in expressing the environment of the real world, this paper has chosen to use Fuzzy OWL language, a fusion of fuzzy concept and standard web ontology language OWL. Accordingly, this paper suggests the following method. First we represent user contacted environmental information with a numerical value and states, and describe it with OWL. After that we transform the converted OWL Context into Fuzzy OWL. As a last step, we prove whether the automatic circumstances are possible in this procedure when we use fuzzy inference engine FiRE. With use the suggested method in this paper, we can describe Context which can be used in the ubiquitous computing environment. This method is more effective in expressing degree and status of the Context due to using fuzzy concept. Moreover, on the basis of the stated Context we can also infer the user contacted status of the environment. It is also possible to enable this system to function automatically in compliance with the inferred state.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.2
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• pp.49-58
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• 2015

Up to the present point in time, the level diagnosis system for urban reactivation have utilized various methods for establishment and management in Korea and overseas, such as city competitiveness evaluation, urban decay diagnosis, etc. However, contrary to performing diagnosis and evaluations on general cities in existing studies, it is found to be a very complex and difficult task to perform a diagnosis on the level of U-City due to its unique characteristics. It is difficult to determine the level of a U-City using a level diagnosis system used for general cities because a U-City is comprised of a connection/fusion of various structural elements. Therefore, in order to perform a systematic diagnosis of a U-City, it is necessary to primarily observe the structural characteristics of a U-city to derive a diagnosis system based on the relativity between each structural element. This study aims to propose a directivity of a U-City level diagnosis system in comprehensive consideration of various elements, such as the objective of a U-City, as well as the structural elements that compose a U-City based on the definitions prescribed in U-City legislations, including ubiquitous city planning, ubiquitous city infrastructure, ubiquitous city technology, services, etc. The results of this study are expected to provide a resolution for the regional quality differences of U-Cities, and also establish a stepping-stone for the realization of U-Cities with high degree of completion.