• 한국정보디스플레이학회:학술대회논문집
• /
• 2005.07b
• /
• pp.1466-1469
• /
• 2005

We report effects of electrical aging on the emission stability of carbon nanotube (CNT) paste for low cost and high low-cost and large area field emission devices or displays. Photosensitive carbon nanotube paste was formulated by using of spin on glass (SOG) as an inorganic binder and investigated emission properties and stability depending on electrical aging condition.

• Journal of the Korean Ceramic Society
• /
• v.33 no.11
• /
• pp.1231-1236
• /
• 1996

The electrode resistance of semiconducting PTC BaTiO3 ceramic material was studied in some detail. Comme-rical In-Ag paste In-Ga alloy and electroless plated Ni as well as evaporated Al were chosen as electrode. The contact resistance of electroded samples were measured by both dc resistivity and ac impedance analysis. The aging effect on contact resistance under cyclic loading from -1$0^{\circ}C$ to 85$^{\circ}C$ was also monitored for the prolonged period of time. In case of Al electroded samples the heat treatment and protective coating had effects on the stability against contact resistance degradation. It was also found that the samples with commercial In-Ag paste and electroless plated Ni electrode had good properties of contact resistance against aging.

• Proceedings of the KIEE Conference
• /
• 1998.07d
• /
• pp.1422-1424
• /
• 1998

This paper deals with the surface aging and electrical characteristics of EPDM specimen with cooling and heating cycle. Then dielectric loss and weight loss are measered to evaluate electrical properties of EPDM on bulk and surface The specimens which underwent aging cycle over 600 hr reveal severe erosion on EPDM surface

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1993.05a
• /
• pp.88-91
• /
• 1993

In this study 9.5/65/35 PLZT was selected which has the excellent quadratic electro-optic property and slim-loop. It was fabricated by the methods of vacuum hot-pressing and sintering. The electrode of color filter was evaporated using the interdigital type masks. Hysteresis and transmission characteristics were measured. The coercive field and the nontransmited field were correlative. Aging effect was measured according to time at same temperature. Wavelengths of RGB were chosen 700[nm] for red, 545[nm] for green and 435[nm] for blue by the standard of the Commission Internationale del Eclaiage.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2002.10a
• /
• pp.24-28
• /
• 2002

Composite reinforced fiber materials are used in lots of fields such as a part of aeronautic space, ship, machinery and so on because can make structure wished for necessary condition by control fiber direction and laminated sequence. As the use of advanced composites increase, specific techniques have been developed to repair changed composite structures. In order to repair the damaged part production high quality composite reinforced fiber are completed by control the surrounding temperature and press in autoclave. The quality is influenced heat exposure degree by chemical reaction for precessing. This study considerated influence limit of using by repair structure part and change of properties according to heat exposure degree for repairing.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.131-136
• /
• 2003

CF8M cast austenitic stainless steel is used for several components such as primary coolant piping, elbow, pump casing, and valve bodies in light water reactors. These components are subject to thermal aging at the reactor operating temperature. Thermal aging results in spinodal decomposition of the delta-ferrite leading to increased strength and decreased toughness. In this study, three kinds of the aged CF8M specimen were prepared using an artificially simulated aging method. The objective of this study is to summarize the method of estimating ferrite contents, Charpy impact energy and J-R curve, and to evaluate the thermal embrittlement of the CF8M cast austenitic stainless steel piping used in the domestic nuclear power plants.

• Journal of the Korea Concrete Institute
• /
• v.12 no.6
• /
• pp.35-42
• /
• 2000

In paper I, the relationships between compressive strength and splitting tensile strength or modulus of elasticity were proposed. In this paper, new prediction model is investigated from estimating splitting tensile strength and modulus of elasticity with curing temperature and aging without compressive strength. New prediction model is based on the model which was proposed to predict compressive strength, and splitting tensile strength and modulus of elasticity calculated by this model are compared with experimental values of paper I. To evaluate in-situ applicability of the model, strength and modulus of elasticity tested with variable temperatures are estimated by the prediction model. The prediction model reasonably estimates the strength and the modulus of elasticity of type I and V cement concretes tested in paper I and experimental results with variable temperature tested in this paper.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.576-580
• /
• 2008

Rubber material properties and useful life evaluation are very important in design procedure to assure the safety and reliability of the rubber components. In this paper, the evaluation of characteristics and useful life prediction of rubber component for elevator cabin were experimentally investigated. The material test and accelerated heat-aging test were carried. Rubber material constants were obtained by curve fittings of simple tension, pure shear and bi-axial tension test data. Heat aging test results changes as the threshold are used for assessment of the useful life and time to threshold value were plotted against reciprocal of absolute temperature to give the Arrhenius plot. By using the rubber material and component test several useful life prediction equations for rubber component were proposed. Predicted useful life of rubber component for elevator cabin agreed fairly with the experimental lives.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.12 no.4
• /
• pp.181-190
• /
• 2004

The interest of the fatigue life of rubber components such as engine mounts is increasing according to the extension of warranty period of the automotive components. Automotive engine mounts get damaged due to thermal and mechanical loadings. This paper discusses a fatigue life prediction of the 3-dimensional dumbbell specimens for natural rubber compound considering the effects of maximum strain and heat aging temperature. Displacement controlled fatigue life tests were performed using specimens with different levels of maximum strain and various hardness. The basic mechanical properties test and the fatigue test of aged rubber specimen under normal and elevated temperature were executed. A procedure to predicted the fatigue life of vulcanized natural rubber material based on the maximum strain method was proposed, and then this curve was in good agreement with fatigue test data less than 200% error range.

• Elastomers and Composites
• /
• v.21 no.3
• /
• pp.205-212
• /
• 1986

The dielectric properties of natural rubber are very important to investigate the molecular structure. The charcteristics of the dielectric absorption in aging natural rubber were studied in the range of frequency from $1{\times}10^3Hz\;to\;3.2{\times}10^7Hz$ at the temperature of $23^{\circ}C$. As the results, it has been confirmed that in the case of aged NR vulcanized specimen with contained sulfur 2 phr above the specimens exhibit two kind of dielectic losses due to the the dipole polarization by impurities and sulfurs, and of raw rubber exhibit the kind of losses due the to dipole polarization. Particularly, it has been affirmed that the dielectric loss spectrum of the aging natural rubber is larger than that the natural rubber, and the dielectric strength of the aging natural rubber drop depreciate respctively.