• The Journal of the Korea Contents Association
• /
• v.17 no.9
• /
• pp.396-405
• /
• 2017

Main purpose of this study is to analyze determinants of household debt among middle and old individuals aged between 32 and 76 that include Korean baby-boomers(born between 1955 and 1963), using a HAPC (Hierarchical Age-Period-Cohort) model and Korean Welfare Panel Study 2006-2016. This study includes 86,056 individuals. Research findings indicate that aging and period effects have statistically significant relationships with household debt levels, however, cohort effects including a baby-boomer generation do not. While household debt increases by 3,530,000 Korean won as age increases by one year, the rate of increase in household debt reduces as individual ages. In addition, employment and health status at the individual level have significant effects on household debt levels. The unemployed are more likely than the employed to have high household debt levels while unhealthy people tend than healthy people to have high household debt levels.

• Journal of the Korean Ceramic Society
• /
• v.49 no.3
• /
• pp.231-235
• /
• 2012

Plasticity is the ability of clay to respond to pressure with a continuous and permanent change of shape in any direction without breaking apart, and hold that shape when released. In this work, the effect of water content and aging period on the plasticity of porcelain clay was evaluated using the capillary rheometer to measure the flow rate and the shear stress. The shear stress of porcelain clay was slightly increased with increasing the aging period, indicating that the plasticity of porcelain clay was influenced by an organic content. It was also observed that the water content in the porcelain clay had a great influence on the plasticity of porcelain clay. The shear stress with water content of 21 wt% was sharply increased with increasing shear rate, but the shear stresses with water contents of 24 and 27 wt% is gently incremented.

• Journal of the Korean Society of Tobacco Science
• /
• v.28 no.2
• /
• pp.67-74
• /
• 2006

This study was carried out to investigate the changes of essential oils in flue-cured leaf tobacco during aging for 21 months. The threshed leaf tobacco(BlO) produced in 2002 crop year was aged for 21 months in the warehouse of Oc-Cheon Leaf Tobacco Processing Factory. The leaf tobacco were sampled at three month intervals for analysis of volatile compounds. Volatile compounds were identified by GC/MS and comparison of gas chromatographic retention time with those of the authentic standard. The total of 75 compounds from the steam volatile concentrate of the flue-cured leaf tobacco were identified; they were 15 hydrocarbons, 12 alcohols, 3 aldehydes, 18 ketones, 7 esters, 10 acids, 3 phenols, 4 furans, 2 pyrrols and 1 pyridine. The major components of essential oil were neophytadiene, solanone, megastigmatrienone and phytol. After a aging period of 21 months, most of volatile compounds showed a gradual increasing tendency.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.48 no.1
• /
• pp.13-16
• /
• 2003

Seeds of burcucumber were treated with accelerated aging, cold-stratification, and light quality illuminated during desiccation to enhance their germination and seedling emergence. The germination was increased by aging and cold-stratification although the latter treatment showed greater effectiveness than the former one. In the combined treatment of aging 6 days at $45^{\circ}C$ and cold-stratification, the germination was promoted under longer period of cold-stratification to reach nearly 100% in 3 week cold-stratification on the ninth day from sowing. In the sequentially combined treatment of aging, cold-stratification, and light quality during 24 hour desiccation at $35^{\circ}C$, no-stratified seeds showed the highest rate in red light treatment but the lowest in far-red light. This implies that the phytochrome action run during the desiccation of imbibed seeds. The red light exposure during drying for the cold-stratified seeds after aging accelerated the germination even more than the dark treatment and germinated 100% on the next day of sowing. It is concluded that the sequential treatment of aging, cold-stratification, and red light illumination during desiccation can highly promote percentage and speed of burcucumber seed germination.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.1447-1448
• /
• 2011

The CSPE cables are used for three years in nuclear power plant. The accelerated thermal aging of chloro sulfonate polyethylene(CSPE) jacket of test cables were carried out for the period equal to 10, 20 and 30 years in air at 90 and $100^{\circ}C$, respectively. The electrical volume resistivity, density, XPS, FE-SEM, EDS and XRF of the accelerated thermal aging of CSPE were measured. The validation of condition monitering method of accelerated thermal aging CSPE was estimated by them. The best validation of condition monitoring method of accelerated aging CSPE is electrical volume resistivity because change thermal of the specimen showed distinction.

• Korean System Dynamics Review
• /
• v.16 no.1
• /
• pp.75-91
• /
• 2015

The price-volume in land by land categories is evaluated with dynamic approaches in the era of aging society This research tries to investigate in the respect of major factors such as real estate, macro-economics, and population that is simulated by land categories. The system dynamics approaches on price-volume in land are forecasted until 2020 using the data in the period of 2000-2014. In regard to methodologies, this research adopted system dynamics to evaluate the relationships between price-volume in land and aging society. The meaningful results have been found during the last over 10 year's analysis as the dynamic relations with major factors. Regarding land categories, this research tries to overcome former research limitations. As an implication from the price-volume in land, it confirmed that the multifaceted aspects show that system dynamics approach effectively simulated them by price-volume in land with the population of aging society.

• Earthquakes and Structures
• /
• v.6 no.2
• /
• pp.127-140
• /
• 2014

Laminated rubber bearing is very popular base isolation of earthquake engineering pertaining to the passive structural vibration control technologies. Rubber used in fabricating NRB and LRB can be easily attacked by various environmental factors such as oxygen, heat, light, dynamic strain, and organic liquids. Among these factors, this study carried out thermal aging test to investigate the effect of thermal aging on the mechanical properties of laminated rubber bearings in accelerated exposure condition of $70^{\circ}C$ temperature for 168 hours. The compressive-shear test was carried out to identify the variation of compressive and shear properties of the rubber bearings before and after thermal aging. In contrast to tensile strength and elongation tests, the hardness of rubber materials showed the increasing tendency dependent on exposure temperature and period. Based on the test results, the property changes of rubber bearing mainly aged by heat are quantitatively presented.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.24 no.4
• /
• pp.66-72
• /
• 2020

In this report, the post-curing and chemical aging ratio of propellants are described according to several aluminum contents. Under the same curing conditions, it was confirmed that the post-curing period of propellant having the aluminum content of 18 wt% was longer than the propellant having the 2 wt% of aluminum. On the other hand, in the chemical aging ratio analysis including post-curing, the propellant having the 18 wt% of aluminum was confirmed that the chemical aging proceeds slowly compared to the propellant having an aluminum content of 2 wt%.

• Journal of Mechanical Science and Technology
• /
• v.19 no.6
• /
• pp.1229-1242
• /
• 2005

When natural rubber is used for a long period of time, it becomes aged; it usually becomes hardened and loses its damping capability. This aging process affects not only the material property but also the (fatigue) life of natural rubber. In this paper the aging effects on the material property and the fatigue life were experimentally investigated. In addition, several fatigue life prediction equations for natural rubber were proposed. In order to investigate the aging effects on the material property, the load-stretch ratio curves were plotted from the results of the tensile test, the compression test and the simple shear test for virgin and heat-aged rubber specimens. Rubber specimens were heat-aged in an oven at a temperature ranging from $50^{\circ}C$ to $90^{\circ}C$ for a period ranging from 2 days to 16 days. In order to investigate the aging effects on the fatigue life, fatigue tests were conducted for differently heat-aged hourglass-shaped and simple shear specimens. Moreover, finite element simulations were conducted for the specimens to calculate physical quantities occurring in the specimens such as the maximum value of the effective stress, the strain energy density, the first invariant of the Cauchy-Green deformation tensor and the maximum principal nominal strain. Then, four fatigue life prediction equations based on one of the physical quantities could be obtained by fitting the equations to the test data. Finally, the fatigue life of a rubber bush used in an automobile was predicted by using the prediction equations, and it was compared with the test data of the bush to evaluate the reliability of those equations.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.50 no.3
• /
• pp.121-129
• /
• 2001

In this paper, a new efficient feature extraction method based on Daubechies discrete wavelet transform is presented. This paper especially deals with the assessment of process statistical parameter using the features extracted from the wavelet coefficients of measured acoustic emission signals. Since the parameter assessment using all wavelet coefficients will often turn out leads to inefficient or inaccurate results, we selected that level-3 stage of multi decomposition in discrete wavelet transform. We make use of the feature extraction parameter namely, maximum value of acoustic emission signal, average value, dispersion, skewness, kurtosis, etc. The effectiveness of this new method has been verified on ability a diagnosis transformer go through feature extraction in stage of aging(the early period, the middle period, the last period)