• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.3
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• pp.284-291
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• 2002

An attempt was made to evaluate the degree of aging degradation in thermally aged 2.25Cr-1Mo steel by electrical resistivity measurement. Artificial aging was performed to simulate the microstructural degradation in 2.25Cr-1Mo steel arising from long time exposure at $540^{\circ}C$. Microstructural parameter (amount of solid solution element), mechanical property (ductile-brittle transition temperature) and electrical resistivity were measured to investigate the mutual relationship among these parameters. Depletion of solid solution element(Mo and Cr) in matrix was detected after aging. The ductile-brittle transition temperature(DBTT) increased rapidly in the initial stage of aging and then saturated afterward. On the other hand, the electrical resistivity decreased rapidly in the beginning and then saturated in the later stage of aging.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.420-422
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• 2003

Aging and failure of motor insulation depend on the stresses imposed on it. The insulation life time depends on the severity of the stresses. The electrical aging by transient surge is very important to traction motor in EMU(electric multiple unit). This paper Presents the insulation characteristics of stator coil by transient surge from inverter. There are several nondestructive tests available for checking the condition of motor insulation, the probable extent of aging,. and the rate of which aging is taking pace. So the insulation characteristics of stator coil were each analyzed by measurement of leakage current, dielectric loss($tan{\delta}$), capacitance, polarization index(PI) and partial discharge. The method of diagnosis is able to analyze the aging condition and Predict the life of the traction motor in EMU.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.623-627
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• 2003

Aging and failure of motor insulation depend on the stresses imposed on it. The insulation life time depends on the severity of the stresses. The electrical aging by transient surge is very important to traction motor in EMU(electric multiple unit). This paper presents the insulation characteristics of stator coil by transient surge from inverter. There are several nondestructive tests available for checking the condition of motor insulation, the probable extent of aging, and the rate of which aging is taking place. So the insulation characteristics of stator coil were each analyzed by measurement of leakage current, dielectric loss($tan{\delta}$), capacitance, polarization index(PI) and partial discharge. The method of diagnosis is able to analyze the aging condition and predict the life of the traction motor in EMU.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1285-1287
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• 2003

The aging of the insulation reduces the electrical and mechanical strength of the insulation. At same point, a voltage surge or mechanical shock from a traction motor start will fracture or break down the insulation. To achieve the expected life usually requires extensive laboratory evaluation of the insulation systems and the use of accelerated aging tests. There are several nondestructive test available for checking. the condition of motor insulation, the probable extent of aging, and the rate of which aging is taking place. So the insulation characteristics of stator coil were each analyzed by measurement of dielectric loss($tan{\delta}$), capacitance and partial discharge. The method of diagnosis is able to analyze the aging condition and predict the life of the traction motor.

• Journal of Welding and Joining
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• v.21 no.2
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• pp.97-101
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• 2003

The change of microstructures in the base metal during transient liquid phase bonding process of directionally Ni base superalloy, GID-111 was investigated. Bonds were fabricated using a series of holding times(0~7.2ks) at three different temperatures. The flip chip bonding utilizing self-aligning characteristic of solder becomes mandatory to meet tolerances for the optical device. In this paper, a parametric study of aging condition and pad size of samples was evaluated. A TiW/Cu/electroplated Cu UBM structure was selected and the samples were aging treated to analyze the effect of intermetallic compounds with the time variations. An FIB technique was applied to the preparation of samples for TEM observations. An FIB technique is very useful to prepare TEM thin foil specimens from the solder joint interface. After aging treatment, the tendency to decrease in shear strength was measured and the structure of the solder and the UBM was observed by using SEM, TEM and EDS. As a result, the shear strength was decreased of about 21% in the 100${\mu}{\textrm}{m}$ sample at 17$0^{\circ}C$ aging compared with the maximum shear strength of the sample with the same pad size. In the case of the 12$0^{\circ}C$ aging treatment, 18% of decrease in shear strength was measured at the 100${\mu}{\textrm}{m}$ pad size sample. An intermetallic compound of Cu6Sn5 and Cu3Sn were also observed through the TEM measurement by using.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.204-207
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• 2003

The flip chip bonding utilizing self-aligning characteristic of solder becomes mandatory to meet to tolerances for the optical device. In this paper, a parametric study of aging condition and pad size of sample was conducted. A TiW/Cu UBM structure was adopted and sample was aging treated to analyze the effect of intermetallic compound with time variation. After aging treatment, the tendency to decrease in shear strength was measured and the structure of the fine joint area was observed by using SEM, TEM and EDS. In result, the shear strength was decreased of about 20% in the $100{\mu}m$ sample at $170^{\circ}C$ aging compared with the maximum shear strength of same pad size sample. In the case of the $120^{\circ}C$ aging treatment, 17% of decrease in shear strength was measured at the $100{\mu}m$ pad size sample. Also, intremetallic compound of $Cu_6Sn_5$ and $Cu_3Sn$ were observed through the TEM measurement by using an FIB technique that is very useful to prepare TEM thin foil specimens from the solder joint interface.

• Korean Journal of Food Science and Technology
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• v.39 no.5
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• pp.584-587
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• 2007

The effect of molar substitution (MS, 0.030-0.118) on the dynamic rheological properties of hydroxypropylated rice starch pastes (5%, w/w) was investigated by small-deformation oscillatory measurements during aging. The magnitudes of storage (G#) and loss (G") moduli measured at $4^{\circ}C$ before aging increased with an increase in MS in the range of 0.030-0.118, while those of tan ${\delta}$ (the ratio of G"/G#) decreased. The G# values of hydroxypropylated rice starches, as a function of aging time (10 hr) at $4^{\circ}C$, increased rapidly at the initial stage, and then reached a plateau region at shorter aging times. However, for the native starch, the plateau values were not observed for G# after a long aging time. Increasing the MS resulted in a decrease in plateau values. The rate constant (K) for structure development during aging was described by first-order kinetics. The K values of hydroxypropylated rice starches at 0.086 and 0.118 MS were much lower than the K value at 0.030 MS.

• Composites Research
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• v.22 no.3
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• pp.35-43
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• 2009

In this study, for a radiator hose made of carbon black filled EPDM(ethylene-propylene diene monomer) rubber, a measuring method of crosslink density was established to analyze the aging behaviors under thermo-oxidative stresses. At $125^{\circ}C$, the crosslink density of the rubber specimens decreased slightly in the initial stage, but increased with increasing the aging time. Such variation in crosslink density was similar to that of tensile strength. This might be due to the formation of sulphoxide crosslinks as well as to additional crosslinks made by the reaction of unvalcunized sulfurs. A high temperature aging of rubber specimens at $180^{\circ}C$ caused a slight increase in crosslink density while it did a large decrease in tensile strength and elongation. With aging at high temperature, the formation of carbonyl groups in EPDM molecule chain and formation of sulphoxide crosslink, rather than the crosslink density variation itself, had a large influence on such changes in mechanical property.

• IEMEK Journal of Embedded Systems and Applications
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• v.8 no.1
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• pp.31-42
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• 2013

Considerations of how to facilitate aging-in-place(AIP) are becoming increasingly pertinent as care-givers are overwhelmed by an aging population. Aging friendly home-care services combined with IT can satisfy the needs of the elderly suffer from chronic diseases such as depression and dementia. Therefore, we propose future smart phone services and application technologies which can estimate emotional states of the aged and respond to the desire to be happy with mental health, connectedness and consolation from peoples. Firstly, we introduce depression measurement techniques to estimate the severity of depression using multiple sensors. At second, the emotional responding services are categorized to four parts and the details are described. Lastly, we propose the process to implement emotional communication and the application techniques(services) to fulfill the emotional satisfaction and mental healthcare for AIP using smart phone as a mediator.

• Journal of Biomedical Engineering Research
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• v.10 no.3
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• pp.261-268
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• 1989

The characteristics of aging of near-equiatomic Ni-Ti alloy has been studied by the three point bend test and the measurement of Differential Scanning Calorimetry(DSC). The DSC is used to measure precise transformation temperatures and the amount of thermal energy required for the corresponding phase transformation. The effort of hardness on aging treatment in saline solution of $37^{\circ}C$ was higher for the annealed than solution treated specimens. As the testing temperature inc- rease from under $M_f$ to above $A_f$ temperature, the elastic stiffness increased. Almost full recovery can be achieved after bending below Belo outer fiber strain. Total bend recovery decreased gradually as aging time and bend angle is increased.