• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.132-135
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• 1990

This paper presents prediction of insulation lifetime in stress. Essentially, Epoxy resin, when it was subjected to different types of aging condition, produced to varieties of electrical properties and lifetime using spectroscopy and breakdown test. The relationships between the structural and electrical changes of aged epoxy were Investigated.

• KSBB Journal
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• v.17 no.4
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• pp.326-332
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• 2002

The quality of biopharmaceutical proteins is strongly affected by a manufacturing process employed to produce Et, and thus validation of the manufacturing bioprocess is a very important issue. Chromatography is probably the most widely used bioprocess unit operation for protein purification. In this study, a miniaturized automatic chromatography system was designed and constructed for scale-down studies for process chromatography validation. This system, named MiniValChrom, has the following features: automatic and repeated operation, flexible sequences and intervals among the steps, on-line and real-time monitoring and control, method files savings, etc. Using the MiniValChrom, we peformed a case study of an abbreviated experiment to estimate chromatographic resin lifetime. BSA (bovine serum albumin) and Cibacron Blue 3G-A were used as the model protein and the resin, respectively. The resin deterioration was evaluated by determining and monitoring the HETP and NTP values from the chromatograms every 5 cycles. It was observed that the HETP and the NTP values were changed by 9% after 15 cycles. The resin lifetime validation could be completed by repeating this experiment until the HETP value reached a predetermined value. The MiniValChrom's concept and the protocol suggested in this study can serve as a rapid and economical tool for the validation studies of bioprocess chromatography system.

• Bulletin of the Korean Chemical Society
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• v.29 no.2
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• pp.339-341
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• 2008

Catalytic trimerization of isobutene to produce triisobutenes has been performed over cation-exchange resin and zeolite catalysts. Resin catalysts have the advantage of long lifetime and high trimers selectivity even though the regeneration of an aged catalyst is not satisfactory. On the contrary, zeolite catalysts can be regenerated facilely by simple calcination in air even though the lifetime is short and trimers selectivity is low probably due to small pore size and strong acidity, respectively. It is, therefore highly desirable to develop an inorganic acid catalyst with macro- or meso-pores to show catalytic performances similar or superior to those of macroporous resin catalysts.

• Conservation Science in Museum
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• v.10
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• pp.75-88
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• 2009

The purpose of this study is to determine the lifetime of acrylic resin Paraloid^TM B-72(EMA copolymer), which is widely used as a coating for metallic artifacts to prevent corrosion. Lifetime factor with temperature, selected chromaticity as the test parameter for lifetime prediction. The found result is that the temperature is the most crucial factor influencing the prediction of the lifetime of the EMA copolymer coated iron surface against corrosion. The simulation results, based on Arrhenius Equation, showed that the lifetime prediction of the EMA coated iron surface was 24.5 years at 16℃, 17.1 years at 20℃, and 12.0 years at 24℃, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.9
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• pp.758-763
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• 2000

Dielectric strength of insulators made of epoxy composites rapidly decreases due to ageing to interfaces between the matric resin and filler particles. The adhesion variation of interfaces caused by moisture absorption also alters electrical properties that are the basic characteristics of insulators, particularly, in outdoor use. In this paper, electrical properties of epox/SiO$_2$composites were investigated at boiling absorption condition to observe the influences of moisture. In order to analyze the basic physical properties of samples, scanning electron microscopy and DC, AC and impulse voltage dielectric strength were measured. Also, the breakdown time of samples was measured under AC 6[kV] applied voltage, and the variation of lifetime was verified by using Weibull distribution function.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.6
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• pp.96-102
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• 2000

The finishing process for dies and molds is an important process because it has influence on final quality of products. And it is difficult to automatize finishing process so that the process has depended on expert's skill until now. However, recently a study on development of die automatic finishing machine has been progressed, and actually this machine is applied to fabrication of die. But the research about tooling system is not enough and finishing tool must have high machining efficiency and adaptability of curved surface. So, this study investigated the application of conductive elastic tool which is composed of metal-resin bonded pellet and elastic backing material. The metal-resin bonded pellet is used to finish the surface by conventional mechanical grinding or electro-chemial grinding method. And elastic backing material is used to follow the curved surface. So conductive elastic tool has long lifetime, uniform removal rate and adaptability of curved surface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.444-447
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• 2003

All objects with some temperature above absolute zero radiate in the infrared. The intensity of the infrared radiated from a object defends on the condition and temperature on the surface of the one. The present, these techniques are frequently adopted into diagnosis for electricity equipments. Simply, however, the applied techniques are passive thermal testing for the detection of loosened terminals and overcurrent. In this paper, a infrared thermal imager was applied to high voltage windings of cast resin transformers, and the accumulated value of the result temperatures was used for evaluating remained lifetime of them. At each aging level, dielectric loss tangent test was carried out. The results offered capabilities for deciding the condition of the transformers suffering difficulties to diagnose.

• Proceedings of the KIEE Conference
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• 2000.11c
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• pp.485-487
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• 2000

Dielectric strength of insulators made of epoxy composites rapidly decreases due to ageing to interfaces between the matrix resin and filler particles. The adhesion variation of interfaces caused by moisture absorption also alters electrical properties that are the basic characteristics of insulators, particularly, in out door use. In this paper, electrical properties of epoxy/$SiO_2$ composites were investigated at boiling absorption condition to observe that influence of moisture. The breakdown time of samples were measured under AC 6[kV] applied voltage, and the variation of lifetime was varified by using Weibull distribution function.

• Journal of the Korean Society of Industry Convergence
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• v.10 no.4
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• pp.207-211
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• 2007

The durable lifetime of RC structures is shortened by various reasons, which are the generation of cracks in construction and service term, the exterior deterioration according to climatic condition, the surface damage due to chloride attack and the corrosion of reinforced bars. The durability of concrete structures is nevertheless able to be increased by the method and the material of reinforcement and repair. The epoxy resin is widely used for reinforment and repair of concrete because of the superiority in mechanical property, adhesive property, abrasion resistance, impact resistance and chemical resistance. The epoxy cement mortar with hardening agent has a lot of disadvantages that are troublesome mixing work, weakened weatherability and high cost for hardening agent. In this study, the mix proportion of mortar is presented just only with epoxy resin and some admixtures, and the test result of mortar without hardening agent shows the higher strength than the mortar with hardening agent. In the mix proportion, the weight of epoxy resin must be less than 15% of the unit weight of cement, and 10% of unit weight of cement is adequate for the weight of admixtures.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.3
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• pp.387-394
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• 2009

It has been observed that coated steel structures are rapidly deteriorated than designed lifetime due to acid rain caused by air pollution etc.. Therefore improvement of corrosion resistance of anti-corrosive paint is very important in terms of safety and economic point of view. In this study corrosion resistance for five kinds of anti-corrosive paints including acryl, fluorine and epoxy resin series were investigated with electrochemical methods such as corrosion potential, polarization curves, impedance and cyclic voltammogram measurements etc.. There were somewhat good relationships between values measured by electrochemical methods such as corrosion current density obtained by cathodic and anodic polarization curves, value of impedance estimated with AC impedance, and polarization resistance on the cyclic voltammogram, for example, corrosion current density was decreased with increasing of values of impedance and polarization resistance on the cyclic voltammogram. However their relationships between corrosion current density and corrosion potential were not well coincided each other. Consequently it is considered that although a corrosion potential of F101 of fuoric resin series shifted to negative direction than other anti-corrosive paints, its corrosion resistance, indicating on the cathodic and anodic polarization curves, AC impedance curves and cyclic voltammogram, was the most superior to other paints, whereas A100 containing arcylic resin showed a relatively poor corrosion resistance compared to other paints.