• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.7-14
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• 2003

A series of laboratory tests, which can show how different curing conditions influence an aging effect on clay, were carried out for the clay samples collected in the area of Kwangyang Bay and Mokpo. Clay samples were remolded and reconsolidated under three different curing temperatures (20, 50, and 80 degree Celsius) and low different curing durations (1, 7, 14, and 40 days). To find out an aging effect and geotechnical characteristics between undisturbed samples and reconsolidated samples, laboratory tests, consisting of uniaxial compression tests, CU triaxial test, and consolidation tests, were preformed. Results showed that the compression index ratio is very useful factor to indicate the aging effect of natural clays. Also geotechnical characteristics of clays reconsolidated at high temperature were very similar to those of undisturbed clays. Finally, curing temperature and curing duration influenced an aging effect on clays. The best curing condition was 80 degree Celsius and 27 days.

• Polymer(Korea)
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• v.25 no.3
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• pp.359-366
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• 2001

Isothermal physical aging of a glass fiber/epoxy composite was examined at different aging temperatures ($T_a$) and degrees of conversion (monitored by the glass transition temperature, $T_g$) by means of the TBA torsion pendulum technique. The range of aging temperature was from 10 to $130^{\circ}C$ : the conversion was systematically changed from $T_g$=$76^{\circ}C$ to $T_g$=$177^{\circ}C$ (fully crosslinked). The effect of isothermal physical aging was manifested as perturbations of the modulus and mechanical loss vs. temperature in the vicinity of $T_a$ for all conversions. The rate of isothermal physical aging determined from the change of modulus with aging time at fixed aging temperature decreased and then increased with increasing conversion below T$_{a}$=9$0^{\circ}C$. There exists a superposition in aging rate vs. ($T_g$ -$T_a$) by shifting horizontally and vertically. This implies that the physical aging process is independent of the change of chemical structure as conversion proceeds. It has been found that water absorbed at the aging temperature below $70^{\circ}C$ during isothermal physical aging lowers the apparent aging rate. It is due to the absorbed water molecules forming strong polar interactions with hydroxyl group on network chain and reducing the segmental mobility during the physical aging.g.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.17 no.1
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• pp.16-33
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• 2004

In Oriental medicine, aging is just a natural process like change of seasons. Ancient Oriental people accepted it as a natural thing to be growing older and to die at last. The science of aging has advanced dramatically. In the last 2 decades, advances in genetics and molecular biology have led to extraordinary new understandings in how cells age, how apoptosis programs cells to die, and how neuroendocrinology plays a role in the lifespan of organisms. Today, the matter of primary concern about aging is a cellular and mitochondrial damage of human body induced by reactive oxygen species(ROS). The skin aging can be divided into two areas, intrinsic(chronologic)-aging and photo-aging. There are lots of photo damage about skin aging. The skin is increasingly exposed to ultraviolet(UV) irradiation in life. Therefore, the risk of photo-oxidative damage of the skin induced by reactive oxygen species(ROS) has increased substantially. Nowadays, many people believe that they can stop or at least delay the process of aging. There are lots of treatments that promise to slow the process of aging and the associated ailments. Many of these treatments, for example, exercise, Vit E, Vit C therapy, hormone therapy, restrict diet, are gradually being subjected to clinical trials. But in spite of all efforts, researches and investigations, there is no single method or treatment which is revealed to be truly effective for delaying progress of aging. Every methods insisted on effect for delaying aging process, has its dark side. All we can do is just keeping ourself healthy until the time of death.

• Journal of the Korean Society for Heat Treatment
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• v.30 no.3
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• pp.99-105
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• 2017

This study was carried out to investigate the effect of heat treatment on the microstructure and mechanical properties in 90% hot forged Incoloy 825 alloy. With increasing solution treatment temperature, the grain size increased and the volume fraction of total precipitates decreased, and the precipitates disappeared at $1,000^{\circ}C$. With increasing aging time at $700^{\circ}C$, the volume fraction of precipitate increased and the precipitates size increased. Most of the precipitates consist $Cr_{23}C_6$ carbide, and a small amount of TiC carbide was also observed. With decreasing solution treatment temperature and increasing aging time, tensile strength and hardness increased, and the elongation and impact value decreased. With increasing aging time, the impact value decreased sharply by the increased of the precipitate size.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.737-742
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• 2002

The chief factors for the penetration and diffusion of chloride ions in concrete are water-cement ratio(w/c), aging, thickness of cover concrete, chloride ions concentration of given environment, wet and dry conditions and etc. In this study, effect of w/c and aging on the characteristics of chloride ions diffusion in concrete were researched when environmental factors for the penetration and diffusion of chloride ions were constant. For this purpose, the voltages passing through the diffusion cell were measured by using accelerated test method using potential difference, and then diffusion coefficients of chloride ions by using Andrade's method were estimated for 44%, 49.5% and 55% of w/c, respectively. As a result, correlation among diffusion coefficients of chloride ions, w/c and aging were concluded through multiple regression model.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.520-525
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• 2001

Compared with the blast furnace slag, steel slag has the expansibility due to the reaction with water and free CaO. Therefore it is specified in Standard Specification for Concrete in Korea that steel slag aggregate must not be used in concrete. So it is unusual to use steel slag aggregate in concrete. In this study steel slag aggregate processed by several aging process was comparatively satisfied with fundamental properties as concrete aggregate, which are specific gravity, absorption, unit weight, percentage of solids and abrasion value etc. And chemical analysis is observed to understand the effect of aging process in steel slag aggregate. When the strength is measured, it is found that the concrete replacing crushed stone with steel slag aggregate had a little problem without sufficient aging process

• Journal of Mechanical Science and Technology
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• v.15 no.1
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• pp.26-34
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• 2001

Most research to date concerning the cryogenic toughness of austenitic stainless steels has concentrated on the base metal and weld metal in weldments. The most severe problem faced on the conventional austenitic stainless steel is the thermal aging degradation such as sensitization and carbide induced embrittlement. In this paper, we investigate the cryogenic toughness degradation which can be occurred for austenitic stainless in welding. The test materials are austenitic stainless JN1, JJ1 and JK2 steels, which are materials recently developed for use in nuclear fusion apparatus at cryogenic temperature. The small punch(SP) test was conducted to detect similar isothermally aging condition with material degradation occurred in service welding. The single-specimen unloading compliance method was used to determine toughness degradation caused by thermal aging for austenitic stainless steels. In addition, we have investigated size effect on fracture toughness by using 20% side-grooved 0.5TCT specimens.

• Journal of Korean Medical classics
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• v.28 no.4
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• pp.1-9
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• 2015

Objectives : The main aims of this study were to identify candidate anti-aging herbal formulae(CAHF) from Dongeuibogam. Methods : We analyzed the terms describing effect of 3,901 herbal formulae on Dongeuibogam and selected the terms describing the anti-aging effect of herbal formulae(TAEHF). Finally, we generated a list of CAHFs based on TAEHFs. Results & Conclusions : 1. We finally selected 162 TAEHFs on Dongeuibogam. 2. We finally selected 138 CAHFs on Dongeuibogam(15CAHFs for external use, 123CAHFs for internal use). 3. TAEHFs are classified into 9 types. 4. CAHFs are classified into 9 types.

• Corrosion Science and Technology
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• v.9 no.5
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• pp.209-215
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• 2010

To elucidate the effect of aging time on resistance to localized corrosion of hyper duplex stainless steel, a double-loop electrochemical potentiokinetic reactivation test a potentiodynamic anodic polarization test, a scanning electron microscope-energy dispersive spectroscope analysis, and a thermodynamic calculation were conducted. With an increase in aging time, sigma phases are precipitated much more than chi phases due to the meta-stable chi phase acting as a transition phase. As aging time at $850^{\circ}C$ increases, the corrosion resistance decreases owing to an increase in Cr, Mo and W depleted areas adjacent to the intermetallic phases such as sigma phases and chi phases.

• Journal of Korea Foundry Society
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• v.12 no.5
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• pp.397-402
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• 1992

The effect of the solution & aging treatment on the tensile strength, yield strength, elongation, reduction of area, hardness was studied in the 17-4 PH stainless steel. SEM pictures were also taken in order to examine the fracture surfaces and precipitated particles. X-ray diffraction patterns for the heat treated samples were also observed. Mechanical properties of the heat treated samples were superior to those of as cast samples. Tensile strength, yield strength, hardeness decreased with the increase of aging temperature. On the other hand, elongation and reduction of area increased as the aging temperature increased.