• Journal of the Korean Society for Heat Treatment
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• v.4 no.3
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• pp.13-20
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• 1991

The present work was aimed to examine the variation of precipitations and mechanical properties by thermomechanical treatments (TMT) in Al-2.19 wt%Li and Al-2.0 wt%Li-0.11 wt%Zr alloys. This study was performed by TEM, SEM observation, DSC, electrical resistance measurement, hardness and tensile strength measurement. First peak of resistivity aged at $90^{\circ}C$ was caused by precipitation of ${\delta}^{\prime}$-precursor phase, and second peak was caused by precipitation of ${\delta}^{\prime}$ phase. According to this result, the precipitation process of Al-2.19 wt%Li alloy was as follow : $SSSS{\rightarrow}{\delta}^{\prime}$-precursor phase ${\rightarrow}{\delta}^{\prime}$ (Coherent ${\rightarrow}$ Semi-coherent) ${\rightarrow}{\delta}$. In a Al-2.0 wt%Li-0.11 wt%Zr ternary alloy, the first peak of resistivity was appeared at initial aging heat-treatment. It is result from exsistant of ${\delta}^{\prime}$-precursor phase. The effect acceleration in a binary alloy was not appeared and the over-aging ternary alloy was accelerated with increase of the reduction rate. It is caused by combination effect of ${\delta}^{\prime}$ and composite phase.

• Journal of the Korea Concrete Institute
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• v.25 no.2
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• pp.137-144
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• 2013

The use of fiber-reinforced polymer (FRP) reinforcing bars in concrete structures has been increased as an alternative of steel reinforcement which has shown greater vulnerability to corrosion problem. However, the long-term performance of concrete members with FRP reinforcement is still questioned in comparison to the used of steel reinforcement. This study presents the results of an experimental study on the long-term behaviors of GFRP (glass fiber reinforced polymer) bar reinforced concrete beams after exposed to accelerated aging in an environmental chamber with temperature of $46^{\circ}C$ ($115^{\circ}F$) and 80% of relative humidity up to 300 days. The objectives of this research was to compare strength degradation and change of ductility between GFRP reinforced concrete beams and steel reinforcement beams after accelerated aging. Two types (wrapped and sand-coated surface) of GFRP bars and steel were reinforced. in concrete beams. Test results show that the failure modes of GFRP bar reinforced concrete beams are very similar with traditional RC beams, and the change of load-carrying capacity of steel reinforcing concrete beam is greater than that of GFRP bar reinforcing concrete beam under the accelerated aging. Test result also shows that the use of GFRP reinforcing in concrete could be introduced more brittle failure than that of steel reinforcing for practical application. The deformability factor up to compression failures indicates no significant variation before and after exposure of accelerated aging.

• 한국노년학
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• v.39 no.3
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• pp.589-612
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• 2019

Korea has undergone rapid modernization and globalization process in the last few decades. The purpose of this study is to explore how shifting traditional values are impacting Korean elderlies and their perceptions of aging experience. In order to understand how changing social and cultural practices are affecting older adults, the similarities and differences among Korean elderlies living in three different geographical locations are examined in a multidimensional comparative framework. Life story interviews were conducted with 30 Korean elderlies (10 urban residents in Korea, 10 rural residents in Korea, and 10 residents in the US). Paying attention to within-group variation, this study particularly focused on analyzing the psychological, social, emotional, and spiritual experiences that made lives meaningful and resilient in old age in spite of physical decline. Based on analysis of narrative, the following major areas were identified as having positive or negative influence on aging experiences: physical health, emotional health, family relationship, work, leisure/social activity, and spirituality. Common themes of aging well across all settings included: "life not indebted to their offspring," "physical and mental health," and "dying well." Spirituality played a critical role in cultivating perspectives on life and accepting aging process, which were rooted in specific religious traditions participants identified (e.g., Christianity or Buddhism). Interesting differences in the meaning of work and leisure were also found between elderlies residing in Korea and the US immigrant context. One unique factor continuing to negatively affect Korean elderly in rural community was related to shame of not obtaining higher education. Implications for future research are also addressed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.217-220
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• 2008

The most important properties in the rubber for a flexible seal are the shear modulus, shear stress, reproducibility of rubber properties from lot to lot and shear modulus variation as aging. This study was conducted to confirm a rubber characteristic for the flexible seal. As a test result, the shear modulus is the range of 0.4310 ${\sim}$ 0.4997MPa, and failure shear stress is above 2.5MPa. After 1 year, the shear modulus of rubber as aging increased about 11.8%.

• Journal of the Korean Society for Heat Treatment
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• v.4 no.3
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• pp.7-12
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• 1991

Effects of Mo content and aging conditions on the amount of retained austenite and mechanical properties of 18 Ni maraging steels were investigated. Maraging steels were fabricated with variation of Mo content. 3, 5, 7, 9% and heat treated by austenitizing at $840^{\circ}C$ for 1 hour and then aged at $480^{\circ}C$ for 0.5~100 hours. It was found that the amount of retained austenite after aolution treatment was negligible up to 5% Mo. 8 and 11 volume percents of retained austenite were obtained with 7 and 9% Mo respectively. The maximum hardness and yield strength without great loss of impact toughness were attained in the range of 4~8 hours of aging time at $480^{\circ}C$ with 5% Mo. It was concluded, as a result, that the optimum Mo content for the good combination of strength and toughness is to be 5% Mo.

• Fashion & Textile Research Journal
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• v.14 no.1
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• pp.130-135
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• 2012

The purpose of this study was to investigate the variation of regional skin temperature with thermography during exercise. Seven men completed 82-min trials which consisted of rest, exercise of $VO_2$ max 60% and recovery period at $30{\pm}0.5^{\circ}C$ and $60{\pm}5%RH$. Changes in skin temperature due to physical activity varied, depending region of the body. The skin temperature of the chest was significantly lowered and that of the back was significantly increased after exercise period(p < 0.05). There were significant negative relationship between the skin temperature of the chest and thermal comfort sensation, and positive relationship between skin temperature of the back and thermal comfort sensation(p < 0.05). It would be better to keep the chest warm, and the back cool during exercise. The skin temperature changed differently on body site due to exercise, and it was influenced by blood flow, sweating and air movement. This study would be meaningful in that the change of regional skin temperature during exercise was investigated consecutively with thermography. In further study, it would be more realistic to measure physiological response with functional sportswear which applies different functional fabric based on skin temperature.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.4 no.1
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• pp.21-30
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• 1974

A study was performed to investigate the degree of similarities and differences in components of craniofacial complex between Korean twins and normal children by lateral cephalometric analysis. Dimensions of S-N, S-Ba, N-Ba, Go-Me, Ar-Go and Ar-Me were against linear measurement and angles of N-S-Ba and gonial against measurement in twins and control groups. The lateral cephalograms of twin were composed of 88 twins aged from 7 to 12:44 males aged 10.65 and 44 females aged 9.55, while those of 50 normalities were composed of 25 males and 25 females aged 10.9 respectively. In order to analyze growth proportion and sexual differences, twins were divided into 3 groups according to two year age intervals and the author compared male with female in 3 groups. For the purpose of observing similarities and differences in twins and normalities by sex, total twins were compared with normalities. The obtained results were as follows: 1. There was no difference in craniofacial complex between plotted angular normalities. 2. In general, the measurements of male were larger than both twins and normalities, but there were no statistical sexual differences in both groups. 3. The growth proportion of mandible by aging was larger than that of face twins and those of female significances of in twins. 4. The growth pattern of gonial angle showed slightly reducing tendency in twins by aging. 5. There was little difference in the growth proportion of both male and female.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.732-735
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• 2009

In this paper, high Xe(Ne+Xe 10%, 20%, 30%) AC-PDP's discharge characteristics according to aging time were studied. The static margin, Vt close curve, discharge time lag was measured for experiments. According to increase of Xe partial pressure, the static margin and luminance was increased. As the result of analysis for misfiring probability, the misfiring is frequently occurred in accordance with increasing of aging time. To improve misfiring, we proposed 3Reset waveform and achieved misfiring probability which was improved.

• KIEAE Journal
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• v.7 no.5
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• pp.35-40
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• 2007

The purpose of this study is to execute evaluation experiment to know the evaluation property of lighting environment of residential space for senior people, considering visual characteristics along aging, and finally provide basic data for the lighting plan to ensure the visual amenity. Processes of this study are as follows;1) Analyzed the variation property of visual sensibility and visual ability of senior people along aging. 2) Selected 3 types of life behavior(rest, conversation and reading) after checking life behavior in residential space for senior people based on advanced study. 3) Made the Mock-up Model that Dimming is possible, actual furnace to model. 4) Executed sensitivity evaluation experiment about lighting environment. 5) Analyzed evaluation property of lighting environment of residential space for senior people. Results of this study are as follows, 1) With lens-filter, we got comfort and amenity in bulb-color lamp which has similar color temperature with red of lens filter. 2) Lighting environment tests during conversation : With lens filters, they felt comfort on bulb color in case of higher illuminance than 850lux and daylight color in 500lux. 3) Lighting environment tests at reading : With lens filter, bulb color got better score in brightness and appropriateness than daylight color.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.212-216
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• 2000

ZnO varistors for distribution surge arrester (18kV, 5kA) were developed and tested microstructure and electrical characteristics. Microstructure of ZnO varistor was consisted of ZnO grain, spinel phase and Bi-rich phase. Average grain size of ZnO varistor was $\mu\textrm{m}$ Reference voltage and lightning impulse residual voltage of ZnO varistor exhibited a good haracteristics above 5.5kV and below 11.56kV, respectively. Consequently, discharge capacity which is the most important characteristics of ZnO varistor for surge arrester exhibited excellent properties above 70kA at twice high-current impulse test. Moreover, variation rate of reference voltage and lightning impulse residual voltage showed below 5% and 2% after high-current impulse test, respectively. Leakage current and watt loss of ZnO varistor will not increase during accelerated aging test at stress condition, such as 3.213kV/$115^{\circ}C$/1000h.