• Journal of the Korean Ceramic Society
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• v.38 no.10
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• pp.908-913
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• 2001

Paper sludge Ash (PA) and Fly Ash (FA) wastes are usually land-filled for reclamation or substituted for cements as a resource. It could also offer some advantages when they are substituted for clay to preserve the environment. To recycle those wastes, the sintered specimen made of PA-FA-Clay system were examined to find the microstructure and physical properties. The ratio of clay to wastes was fixed as 30:70 by wt%, while PA to FA within waste portion were varied in the range of $1:6{\sim}7:0$. Those specimens were fired in $1150{\sim}1350^{\circ}C$. It was found that the relative density of sintered specimen was increased with amount of PA added at low sintering temperature (i.e, $1150{\sim}1200^{\circ}C$). This is due to increased amount of liquid during sintering. It is shown, however that at high sintering temperature ($1250{\sim}1350^{\circ}C$), the relative density of specimens was decreased with amount of PA added. This is because of overfiring phenomenon which may be able to induce an inhomogeneous microstructure and increased porosity. The mechanical properties of sintered specimen were depended upon the homogeneity of microstructure in accordance with SEM (Scanning Electron Microscopy) and pore size distribution analysis. For example, the compressive strength of 10PA-60FA-30Clay specimen sintered at $1225^{\circ}C$ was twice higher than that of 70PA-30Clay specimen even thought the relative density of those specimen was similar. This decreased strength of 70PA-30Clay specimen appears to be an inhomogeneity of microstructure due to overfiring.

• Journal of the Korean Society of Clothing and Textiles
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• v.17 no.3
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• pp.491-505
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• 1993

The influences of protease on the removal of various protein soils from cotton fabrics were studied. The human epidermal stratum corneum, hemoglobin and casein were used as protein soils. The soiled fabrics were denatured by steaming for 30 min. before washing and laundered using Terg-O-Tometer under washing conditions. The removal efficiency was evaluated by analysis of protein on the fabrics before and after washing by means of copper-Folin method. The relations between the removal and the characteristics of protease were discussed. Also the degradation of protein were examined by microscopy. The seperation of human epidermal stratum corneum after hydrolysis was examined by SDS-PAGE. The results obtained were as follow : 1. The protein from the soiled cotton fabric was removed effectively by adding protease. The removal of protein was increased in proportion to increasing of the enzyme concentration up to a certain point, but it began to decrease above the point. The removal effect was high in the order of casein>human epidermal stratum corneum>hemoglobin. Especially the protein was more effectively removed in ADS solution(pH 9.5) containing enzyme. 2. When protease was used with ADS. the removal of protein was efficiently showed in relatively short time(5~15min.) compared to using ADS only. It is due to the properties of this enzyme that reacts with very short time. 3. Even at low temperature the removal efficiency of enzyme was relatively higher compared with the activity of enzyme. The removal of protein soil was increased up to a maximum near $50^{\circ}C$, and then decreased. 4. The removal of protein by protease was improved with the increase of alkalinity in the pH range from 9.5 to 11.0 but it began to decrease above pH 11.0. 5. According to the increase of mechanical agitation, the removal effect was increased. But the removal efficiency of protease was more effective compared with the agitation in detergency. 6. According to the SDS-PAGE separation and micrograph it was confirmed that the human epidermal corneum was effectively hydrolysed by the enzyme added. So the fragments of protein were removed more efficiently by means of the interfacial reaction of AOS.

• Journal of the Korean Ceramic Society
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• v.39 no.9
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• pp.896-901
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• 2002

Since many process parameters of FHD(Flame Hydrolysis Deposition) are involved in forming multi-component amorphous silica film ($SiO_2-B_2O_3-P_2O_5-GeO_2$), it has not been easy to predict the optical, mechanical and thermal properties of deposited film from the simple process parameters, such as source flow rate. Furthermore, the prediction of final composition of film becomes even more difficult after sintering at high temperature due to the evaporation of volatile dopants. The motivation of the study was to clarify the quantitative relationship between simple process parameters such as the flow rate of source gases and resulting chemical composition of sintered film. Hence, the compositional analysis of silica soot by FTIR(Fourier Transformation Infrared Spectroscopy) and ICP-AES(Inductively Coupled Plasma-Atomic Emission Spectrometry) under the control of the amount of dopant was carried out to obtain the quantitative composition. By measuring spectrum of absorbance from FTIR, the compositional change of B-O, Si-O, OH($H_2O$) in silica film was measured. The concentrations of these dopants were also measured by ICP-AES, which were compared with the FTIR result. The final quantitative relationship between simple process parameters and composition was deduced from the comparison between two results.

• Korean Chemical Engineering Research
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• v.56 no.4
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• pp.577-584
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• 2018

This study was conducted to investigate the potential of chicken feather (CF), which is a by-product in poultry industry, as a partial substitute of wood fiber in the production of wood-based fiberboard. Keratin-type protein constituted the majority of CF, and its appearance did not differ from that of wood fiber. When the formaldehyde (HCHO) adsorptivities of CF compared by its pretreatment type, feather meal (FM), which was pretreated CF with high temperature and pressure and then grounded, showed the highest HCHO adsorptivity. In addition, there was no difference between the adsorbed HCHO amounts, which was measured by dinitrophenylhydrazine method, of scissors-chopped CF and CF beated with an electrical blender. Mechanical properties and HCHO emission of medium-density fiberboards (MDF), which were fabricated with wood fiber and 5 wt% CF, beated CF or FM based on the oven-dried weight of wood fiber, were not influenced by the pretreatment type of CF. However, when the values compared with those of MDF made with just wood fiber, thickness swelling and HCHO emission of the MDF were improved greatly with the addition of CF, beated CF or FM. Based on the results, it might be possible to produce MDF with improved dimensional stability and low HCHO emission if CF, beated CF or FM is added partially as a substitute of wood fiber in the manufacturing process of MDF produced with the conventional urea-formaldehyde resin of $E_1$ grade. However, the use of CF or FM in the production of MDF has a low economic feasibility at the current situation due to the securing difficulty and high cost of CF. In order to enhance the economic feasibility, it requires to use CF produced at small to medium-sized chicken meat plants. More importantly, it is considered that the technology developed from this research has a great potential to make provision for the prohibition of animal-based feed and to dispose environmentally avian influenza-infected poultry.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.2
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• pp.296-309
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• 1999

Autopolymerized resin facilitates a more rapid and easier means for the construction of removable orthodontic appliances than heat cured resin. But many reports reveal that more unreacted monomer is found in autopolymerized resin. It is very important to achieve maximum degree of polymerization because if polymerization is inadequate, high level of unreacted monomer has been shown to adversely affect mechanical and physical properties, and also the question of allergy or toxicity to methylmethacrylate must be considered. The purpose of this study was to compare the degree of polymerization according to curing method and curing time. Five groups were desinged ; Group 1 was polymerizied at room temperature($28^{\circ}C$) ; Group 2 in $28^{\circ}C$ water ; Group 3 in $28^{\circ}C$ water under 30psi pressure ; Group 4 in $43^{\circ}C$ water ; Group 5 in $43^{\circ}C$ water under 30psi pressure for 10 minutes, 1 hour 12 hours, 1 day and 3 days. The degree of polymerization was measured by means of Fourier Transform Infrared spectroscopy. The results were as follows: 1. The degree of polymerization increased constantly in accordance with curing time in all groups and after curing for 10 minutes, Group 1 showed significantly higher degree of polymerization after 12 hours and Group 2, Group 3, Group 4, Group 5 after 1 hour(p<0.05). 2. The degree of polymerization decreased in the order of Group 5, Group 4, Group 3, Group 2, Group 1 except when the curing time was 1 hour and 12 hours(p<0.05). 3. The degree of polymerization of Group 4, Group 5 cured at $43^{\circ}C$ showed significantly higher degree of polymerization than Group 2, Group 3 at $28^{\circ}C$ except when the curing time was 1 day(p<0.05). 4. Among Group 2, Group 3 and Group 4, Group 5, the pressure had no effect on polymerization except when the curing time was 12 hours(p<0.05). 5. Between Group 1 and Group 2, the method of storage had no effect on polymerization except when the curing time was 1 hour(p<0.05).

• Korean Chemical Engineering Research
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• v.51 no.6
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• pp.766-773
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• 2013

A transparent film was fabricated based on bacterial cellulose (BC), BC has excellent physical strength and stability at high temperature and it is an environmental friendly flexible material. In order to improve the conductivity, silver nanowire (AgNW) and/or graphene were introduced to the BC membrane. The aspect ratio of the AgNW synthesized in this study was 214, with a length of $15{\mu}m$ and width of 70 nm. The higher aspect ratio improved the conductivity by reducing the contact resistance. The thermal and electrical properties of 7 types of films prepared were investigated. Each film was fabricated with rectangular shape ($2mm{\times}2mm{\times}50{\mu}m$). The films were scored with a net shape by a knife, and filled with AgNW and graphene to bestow conductivity. The film filled with AgNW showed favorable electrical characteristics with a thickness of $350{\mu}m$, electron concentration of $1.53{\times}10^{19}$, electron mobility of $6.63{\times}10^5$, and resistivity of 0.28. The film filled with graphene had a thickness of $360{\mu}m$, electron concentration of $7.74{\times}10^{17}$, electron mobility of 0.17, and resistivity of 4.78. The transmittances at 550 nm were 98.1% and 80.9%, respectively. All the films were able to light LEDs bulbs although their brightness differed. A thermal stability test of the BC and PET films at $150{\pm}5^{\circ}C$ showed that the BC film was more stable, whereas the PET film was quickly banded. From these results, it was confirmed that there it is possible to fabricate new transparent conductivity films based on BC.

• Food Science and Preservation
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• v.31 no.3
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• pp.423-432
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• 2024

In this study, a vacuum tumbler with 4 impellers (DVT) was designed and applied for thawing frozen pork (vacuum -60 kPa, jacket 35℃, 1 rpm). Quality characteristics of the thawed pork were compared with those of industrially thawed meat by natural air at room temperature (NAT) and imported vacuum tumbler (IVT). The thawing time for frozen pork (303.36 kg) using DVT (165 min) was much shorter than that of NAT (4,200 min). DVT-thawed pork had lower drip loss (0.85%) than NAT (2.08%). DVT-thawed pork showed a pH of 5.92, a total bacterial count of 1.96±0.02 log CFU/g and no coliforms. Deteriorations in fat (TBARS 0.31±0.01 MDA mg/kg) and protein (VBN 5.67±1.98 mg%) in DVT-thawed pork were significantly lower than those of NAT (p<0.05). DVT-thawed pork had a high water-holding capacity (WHC, 97.5%). The hardness (34.59±0.46 N) and chewiness (188.21±0.17) of cooked DVT-thawed pork were about 5-6 times lower than those of NTA. Microstructure (SEM) showed myofibrillar damage in NAT-thawed pork, whereas dense myofibrillar structure was observed in DVT-thawed pork. DVT was better or similar to IVT in all evaluation parameters. The designed DVT is expected to be used as an efficient thawing method in terms of processing time and yield and to produce thawed meat with high WHC, soft texture, and low spoilage by minimizing tissue damage.