• Journal of the Korean Chemical Society
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• v.45 no.4
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• pp.341-350
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• 2001

Aluminum Hydroxide was employed as a thermal retardent and flame retardent for Chloropolyethylene (CPE) rubbery materials which is the construction material of automotive oil cooler hose. and then cure characteristics, physical properties, thermal resistance and flame retardation of compounded rubber were investigated, and optimum mixing conditions of rubber and flame retarding agent were deduced from the experimental results. CPE rubber material which has excellent properties of chemical corrosion resistance and cold resistance and inexpensive in price was used to prepare rubber specimen. The by-product of ething, produced from the process of surface treatment of aluminum was processed to aluminum hydroxide via crushing and purification, which is characterized by XRD, PSA, SEM and ICP-AES techniques in terms of phase, size, distribution, morphology and components of particles and then mixed to CPE rubber materials in the range of 0~80 phr. Hardness, tensile strength, elongation and thermal properties of compounded rubber specimens were tested. The optimum mixing ratio of rubber to additives to give maximum effect on thermal resistance and flame retardation, within the range of tolerable specification for rubber materials, was determined to be 40 phr. The flame retardation of CPE rubber materials was found to be increased by 5 times at this mixing ratio.

• Food Science and Preservation
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• v.11 no.4
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• pp.508-515
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• 2004

In this study, salting conditions and dehydration methods were investigated. Salting time, concentration and temperature could be considered to variables in salting conditions. The diffused salt amounts to beef jerky depending on time are sharply increased in two hours. This result is caused by the difference decrease of concentration gradient between bulk solution and beef jerky. The increase of salting concentration and temperature resulted also in the increase of a diffused salt. The deeper bulk concentration made diffusion to beef easily with the bigger driving force and the movement of molecules is more active according to temperature increase. Dehydration is conducted with various methods such as natural drying, cold air drying and hot air drying. Comparing with color and texture among the drying methods, cold air drying showed superior quality in color and texture. Beef jerky by cold air drying colored more reddish than other drying methods and good cutting shear stress and tensile strength. In case of hardness and chewiness, hot air drying method showed the highest value, which means the worst texture.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.252-261
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• 2017

This study examined the effect of heat treatment on the microstructure and mechanical properties of J55 line pipe steel. The experiments were carried out at under the following various conditions: austenization temperature($880^{\circ}C$, $910^{\circ}C$, $940^{\circ}C$), cooling methods(water quenching, oil quenching) and tempering temperature(none, $550^{\circ}C$, $650^{\circ}C$). The phase diagram and CCT curve were simulated based on the chemical composition of J55 steel to predict the microstructures. In the results, A1, A3 temperature decreased. As the austenization temperature increased, existing austenite grains grew exponentially which seriously degraded their mechanical properties. Various microstructures, including martensite, bainite, ferrite, and pearlite, developed in accordance with the heat treatments and were closely correlated with hardness, tensile strength and toughness. Martensite was formed after water quenching, but bainite and ferrite appeared after oil quenching. FeC precipitation formed and coarsened during tempering, which improved their toughness.

• Applied Biological Chemistry
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• v.34 no.4
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• pp.373-378
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• 1991

The skin and fleshy substance on the net fiber of sponge-gourd fruit pressed mechanically was removed with 0.2% NaOH solution in $3{\sim}5$ hours. The treatment of 0.2% NaOH with 0.02% Monopol(non-ionogenic polyoxethylen derivative) as surfactnat and with 0.1% $Ca(OCl)_2$ as bleaching agent enhanced the effect to remove the fleshy substance and improve the quality of net fiber. Also, the wet hardness and tensile strength of net fiber were controlled by the crosslinkage of the fiber with glu tardialdehyde, glyoxal, and formalin, respectively. The net fiber was stable on the acid and alkaline solutions. Also the range of temperature to degradate the fiber was $338{\sim}385^{\circ}C$. These values indicated a fair stability. The improved net fiber can be used for raw material of bath, dish washing, oil and gas filter, and many kinds of decorations.

• Applied Chemistry for Engineering
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• v.23 no.2
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• pp.217-221
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• 2012

Blending films having enhanced water-resistance and barrier properties were prepared using the mixtures of poly(vinyl alcohol) (PVA) aqueous solution and poly(ethylene-co-acrylic acid) (EAA) dispersed in water. Thermal-mechanical properties, contact angles, water-vapor transmission rates (WVTR) and oxygen transmission rates $(O_2TR)$ were measured with the content of EAA of blending films, and their water-resistance was evaluated. The tensile strength of the films was found to be $9.16{\sim}11.75\;kg/mm^2$ which showed no significant difference compared with that of PVA, and the hardness increased with the content of EAA. The glass transition temperature and melting temperature of the blending films were slightly improved. The film prepared with PVA/EAA (= 90/10), of which the swelling and solubility were measured to be 109 and 0%, respectively, showed improved water-resistance. The WVTR and $O_2TR$ for the PET film (thickness $50\;{\mu}m$) coated with PVA/EAA (= 90/10) film (thickness $2.5\;{\mu}m$) were measured to be $9.1\;g/m^2/day$ and $2.0\;cc/m^2/day$, respectively.

• Elastomers and Composites
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• v.47 no.1
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• pp.9-17
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• 2012

Herein, life time prediction based on the deterioration of physical properties of chloroprene rubber (CR)aged by heat and seawater was performed. CR samples were experienced an accelerated test at $80^{\circ}C$, $100^{\circ}C$, $120^{\circ}C$ for heat aging, and $40^{\circ}C$, $60^{\circ}C$, $80^{\circ}C$ for seawater aging for 20,000 hrs. The change in tensile strength, maximum elongation,hardness was measured. As a result, the decrease in elongation was a major factor causing failure. The life time estimated using an Arrhenius model was 125 years at $23^{\circ}C$ for thermal aging and 9 years at $23^{\circ}C$ for seawater aging. SEM and elemental analysis reveal that cracks were generated and the content of oxygen was increased for CR agined by seawater. FT-IR spectrum shows the new C-O and C = O bonds were generated by the chemical reaction with seawater. Also, the glass transtion temperature was increased and the thermal decomposition was decreased by seawater aging.

• Elastomers and Composites
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• v.38 no.1
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• pp.57-64
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• 2003

Metal oxide(MgO) was added to FKM rubber in order to develop automotive fuel hose which ran show elastic characteristics under extreme condition. Cure characteristics, physical properties, thermal resistance and fuel resistance of FKM compounded rubber with MgO were investigated. MgO was mixed to FKM rubber materials within the range of $0{\sim}20phr$. From the test results of rheological properties and Mooney viscosity, the $t_{s2}$, $T_{c90}$ values increased as the MgO contents increased in FKM rubber compounding. Hardness and 100% modulus of FKM compounded rubber slightly increased, but tensile strength and elongations at break slightly decreased. From the test results of thermal resistance of rubber specimens at 130, 150, and $170^{\circ}C$ for 70 hrs, the changing rate of physical properties was found to be relatively small. Fuel resistance tests were carried out for fuel A, B, C and D at $40^{\circ}C$ for 70hrs, and the results showed that the changing rate in physical properties was found to increase from Fuel A to D, Furthermore thermal properties of FKM compounded rubber containing MgO were also investigated by using TGA/DSC. The optimum mixing ratio of additive to FKM rubber to get the maximum effect on thermal resistance and fuel resistance, within the range of desirable specification for rubber material, was determined to be 6 phr for MgO.

• Journal of Bio-Environment Control
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• v.17 no.4
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• pp.312-318
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• 2008

In a pear fruit 'Chuhwangbae' was investigated the effect of the calcium-coated double paper bag on the physical properties of the paper bag, micro meteorological phenomena, and calcium contents in quality of fruit. The calcium-coated paper bag, compared with official paper bags, did not give any effect on light transmission ratio and tensile strength. The change of the inside relative humidity of the paper bag was a little compared with conventional paper bags, but there was no difference in temperature. The contents of the accumulated calcium of the pericarp was remarkably greater than conventional paper bags during the period of 65 days to 160 days after the full bloom, but the flesh remarkably increased at 160 days. The calcium content per concentration of calcium coating greatly increased in 12% of yellow double paper bags and 9, 12% of newspaper double paper bags in case of the pericarp, and in 3% of yellow double paper bags and 6, 9, 12% of newspaper double paper bags in case of the pericarp. As a result of treatment of a radioactive isotope, the amount of accumulated calcium in the pericarp continued until 60 hours after treatment, but there was no difference in the calcium amount between the flesh and no-treatment pericarp. As to the hardness of fruits at the time of harvest, there was no difference in the concentration in case of a yellow double bags. But newspaper double paper bags 6, 12% was significantly difference. Soluble solid remarkably increased in yellow double paper bags 6, 9% and yellow double paper bags 3, 6, 9%. Also, it did not effect on changes of the pericarp, fruit weight and the color of the pericarp.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.688-694
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• 2018

The mixture ratio of two-component liquid silicone is important for the inherent physical characteristics of the finished product. Therefore, it is necessary to uniformly control the ratio of the main material and the sub-material. In this paper, a mixing-ratio control system was designed, which consists of a digital flow meter and a flow control system to measure the flow rate of the raw materials and a pumping system to maintain constant pressure and transfer of the raw materials. In addition, a program was developed to control the organic interlocking and mixing ratio. For the verification of the developed system, we compared the actual weight of raw material with the value measured by the flow meter during pumping, and we measured the physical properties of the mixed material by making test samples with and without the application of the mixing-ratio improvement algorithm. The measured value was close to the reference value with a hardness range of 46-47 and tensile strength of 9.3-9.5 MPa. These results show that the mixing ratio of the liquid silicone is controlled within an error range of ${\pm}0.5%$.

• Journal of Conservation Science
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• v.26 no.3
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• pp.335-340
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• 2010

Urethane resin applicable for the first transcription of historical site and transcription of soil layer were synthesized in order to replace the imported urethane resin, NS-10. Comparing to the NS-10, the urethane polymers showed similar penetration to wet soil and formed a stable layer of polyurethane during progress working the peeling off the polyurethane pre-product from epoxy surface of final product. The urethane resins used for the first transcription of historical site improved tensile strength, which is consistent with that of NS-10. In addition the urethane resin for transcription of soil layer was supplied with hardness that have a also same strong point as like NS-10. This property is advantage due to simplifying the transcription work of soil layer in backward. When we tested to the real ground soil as well as experimentation compressed soil with use these synthesis urethane resin, we ca get the satisfying result in penetration property and stability and these properties evaluated the resins as an advanced product serving better convenience for worker.