• Journal of the Korean Ceramic Society
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• v.45 no.11
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• pp.725-733
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• 2008

In this study the preparation method of the spherical ADU droplets, intermediate compound of a HTGR nuclear fuel, was detailed-reviewed and then, the characteristics on an ageing and a washing steps among the wet process and the thermal treatment process on the died-ADU${\rightarrow}UO_3$ conversion with the high temperature furnaces were studied. The key parameters for spherical droplets forming are a precise control of feed rate and a suitable viscosity value selection of a broth solution. Also, a harmony of vibrating frequency and amplitude of a vibration dropping system are important factor. In our case, an uranium concentration is $0.5{\sim}0.7mol/l$, viscosity is $50{\sim}80$ centi-Poise, vibration frequency is about 100Hz. In thermal treatment for no crack spherical $UO_3$ particle, the heating rate in the calcination must be operated below $2^{\circ}C$/min, in air atmosphere.

• Advances in materials Research
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• v.4 no.1
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• pp.1-12
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• 2015

Low carbon steel of composition 0.05C - 0.18 Mn - 0.012 Si is intercritically annealed at temperatures $750^{\circ}C$, $775^{\circ}C$ and $800^{\circ}C$. The equilibrated alloys of different amounts of austenite with varying carbon contents are quenched in iced water. The same alloys are subcritically annealed at $675^{\circ}C$ and $700^{\circ}C$ for varying periods of times; the subcritically annealed alloy samples are quenched in iced water. Optical, scanning electron and transmission electron microscopy are carried out for all the samples. The dislocation structure, its distribution and density present in the above prepared duplex ferrite martensite steels are studied. The martensites are found to be highly dislocated due to lattice invariant deformation. At the same time ferrite adjoining the martensite areas also exhibits quite a high dislocation density. The high dislocation density is favorable for strain ageing and hence bakes hardenability. EDS analyses were carried out for both martensite and ferrite phases; it is found that the degree of supersaturation in ferrite together with carbon content in martensite varies with the process parameters. The microhardness test results show that the hardness values of different phases differ appreciably with process parameters. The microstructures and the corresponding microanalyses reveal that differently processed steels contain phases of varying compositions and different distribution.

• 한국노년학
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• v.40 no.3
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• pp.511-530
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• 2020

The present study aimed to examine the moderating effects of marital satisfaction (MS) on the association between the number of chronic disease (CD) and depressive symptoms (DS) among ol der men and women. The 6th wave of the Korean Longitudinal Study of Ageing was utilized and the sample was married men (N=585) and women (N=460) aged 65 and over. Multiple regression analysis using SPSS WIN 25.0 and Process Macro was used to test moderating effects of MS. Control variables were age, education, household income, parent-child relationship satisfaction, self-rated health, cognitive function, current smoking status and CD of spouse. Resul ts from elderly men showed the moderating effect of MS was significant. Specifically, those with more CD were more likely to report higher level of DS in the low MS group. However, the effect of CD on DS was not significant in the high MS group. Results from elderly women showed the moderating effect of MS was not significant. This study showed the moderating effect of MS on the association between CD and DS differed by gender in later life. It suggests practical intervention to utilize the resources of spouses is in need to promote mentally healthy aging even though having chronically ill in later life.

• The Journal of the Convergence on Culture Technology
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• v.8 no.5
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• pp.207-218
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• 2022

This study, to confirm the mediating effect of knee pain on cognitive functions and depression in older adults, and as an interdisciplinary research between the physical and psychological mechanisms, confirmed the identifying group differences by gender, age, and educational attainment of older adults, and aimed to research the improvement of cognitive functions, which is a main factor of dementia's risk prediction. The analysis data was from the 8th Korean Longitudinal Study of Ageing (KLoSA) in 2020, and the research model was verified using Process macro and model #4. The main analysis results are as follows. First, depression partially mediation effect of knee pain on cognitive functions. Second, the mediation effect of depression by gender was significant, but the direct effect in the male older adults group was twice that in the female older adults; the indirect effect did not vary significantly based on gender. Third, the mediating effect of depression by age was relatively greater in the old-old aged group than in the young-old aged one. Fourth, as for the mediating effect of depression according to the classification of educational attainment, the mediating effect was not significant in the group with a college degree or higher education but was significant in the remaining three sub-groups. Based on the results, this study makes implications for the need for active intervention strategies to improve cognitive functions, focusing on group differences by gender, age, and educational attainment in the management of knee pain and depression.

• Journal of Labour Economics
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• v.27 no.2
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• pp.1-27
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• 2004

The share of self-employment shows a downward trend until 1990 and then an upward trend since then. The upward trend is mainly due to more employers and more male self-employed, which implies that self-employment plays a significant role as an alternative form of employment. This paper examines whether self-employment can be a bridge between no work and wage work in the processes entering into or exiting labor market, and if so, what determines the choice of self-employment as a bridge, using the data from the Korea Labor and Income Panel Survey(Wave 1 to Wave 5). Empirical analysis employing the probit model shows that the older, female, the less educated, and persons with bad health are more likely to choose self-employment as a bridge in the exit process and that they are less likely to choose it as a bridge in the entry process. Business cycle has a statistically significant negative effect on its role of bridge employment in the exit process but not in the entry process. The result implies that, in the ageing society, labor market policy should consider self-employment as a better alternative than wage work for the aged.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.5
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• pp.1125-1131
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• 2012

According to abrupt decrese in number of farmer and ageing society, there has been a need for development of low cost agricultural robot. In this paper, a H/W and S/W platform of caterpillar type agricultural chemical dusting robot based on XP embedded system were described. The developed agricultural robot has 2 d.o.f caterpillar type driving wheel and 2 d.o.f chemical dusting spray mechanical system. The H/W platform of the agricultural robot consists of robot controller, remote controller and sensor controller. In S/W platform, 5 processes work concurrently, which are task manager, TCP-IP communication process, localization process, wheel control, and sensor control process. This robot platform has been developed for chemical dusting robot. We proved this system's validity through field test.

• Journal of Korea Foundry Society
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• v.21 no.1
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• pp.7-14
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• 2001

The research on new DRA(discontinuous reinforced alloy) and CRA(continous reinforced alloy) composites has been carried out to improve the properties of ceramic fiber and particle reinforced metal matrix composites(MMCs). Effects of alloying elements and aging conditions on the microstructures and aging behavior of Al-Si-Cu-Mg-(Ni)-SiCp composite have been examined. The specimens used in this study were manufactured by duplex process. The first squeeze casting is the process to make precomposite and the second squeeze casting is the process to make final composite. The hardening behavior was accelerated with decreasing the size of SiCp particle in the composites. It is considered that the dislocation density increased with increasing SiCp size, due to the different thermal deformation between Al matrix and SiCp during quenching after the solution treatment. Peak aging time to obtain the maximum hardness in 3 ${\mu}m$ SiCp reinforced Al composite was reduced than that in large size(5, 10 ${\mu}m$) of SiCp because of difference in dislocation density. Aging hardening responce(${\Delta}H$ = $H_{Max}.-H_{S.T}$) of composites was greater than that of unreinforced Al alloy because of higher density of second phases in matrix.

• Fashion & Textile Research Journal
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• v.18 no.2
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• pp.244-251
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• 2016

Viscose rayon filament fabrics have been called 'artificial silk' and beloved as summer clothing materials for a long time in Korea. This is because the viscose rayon filament fabrics reveals glossy surface and cool touch feeling compared to other conventional fabrics composed of staple fibers. Therefore, we tried to prepare the higher value added viscose rayon filament fabrics for summer textile products. In this study, we applied gallnut extract to the viscose rayon filament fabric to develop summer fabrics with natural color and multi-functions such as antibacterial and antioxidant properties. This process also pursue eco-friendly and multi-functional fabric finishing from the natural material "gallnut". In addition, various pre-treatment with cationizer, chitosan, or chito-oligomer was applied to the finishing process to improve the finishing efficacy and durability. Consequently, it was found that the active component of gallnut extract was successfully incorporated to the viscose rayon filament fabric through a pad-dry-cure process. And, the treated viscose rayon filament fabrics showed excellent antibacterial and antioxidant properties. Therefore, it was expected that the rayon filament fabrics treated by gallnut extract could be used as effective summer fabrics preventing the growth of bacteria and skin ageing as well as providing cool touch feeling. However, the pre-treatments were not that meaningful on the functionalities but effective on coloring.

• Korean Journal of Materials Research
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• v.26 no.7
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• pp.388-392
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• 2016

A cold roll-bonding process was applied to fabricate an AA1050/AA6061/AA1050 laminate complex sheet. Two AA1050 and one AA6061 sheets of 2 mm thickness, 40 mm width and 300 mm length were stacked up after surface treatment that included degreasing and wire brushing; material was then reduced to a thickness of 3 mm by one-pass cold rolling. The laminate sheet bonded by the rolling was further reduced to 1.2 mm in thickness by conventional rolling. The rolling was performed at ambient temperature without lubricant using a 2-high mill with a roll diameter of 210 mm. The rolling speed was 5.0 m/sec. The AA1050/AA6061/AA1050 laminate complex sheet fabricated by roll bonding was then hardened by natural aging T4) and artificial aging (T6) treatments. The microstructures of the as-roll bonded and the age hardened Al complex sheets were revealed by optical microscope observation; the mechanical properties were investigated by tensile testing and hardness testing. The strength of the as-roll bonded complex sheet was found to increase by 2.9 times compared to that value of the starting material. In addition, the hardness of the complex sheets increased with cold rolling for AA1050 and age-hardening treatment for AA6061, respectively. After heat treatment, both AA1050 and AA6061 showed typical recrystallization structures in which the grains were equiaxed; however, the grain size was smaller in AA6061 than in AA1050.

• The Journal of the Korean dental association
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• v.50 no.1
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• pp.6-12
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• 2012

As in all other parts in the body, oral tissue also undergoes dramatic changes with increasing age. Since these changes occasionally go beyond physiological scope, which may result in pathological changes, it is essential for dentist to understand changes caused by normal aging process. With increasing age, tooth morphology and occlusion also varies, especially loss of hard tissue, which is taking place in lifelong time, occurs as a result of tooth wear. When this loss of hard tissue is presented rapidly or excessively, functional and esthetical problems are raised, resulting in lowering quality of life of patient as well as making dental treatment for oral rehabilitation even more complex. Therefore, based on understanding of change in occlusion with increasing age, strategic approaches for maintenance of oral health in both functional and esthetic aspect are required as appropriate restoration and maintenance for progressive tooth wear enables desirable occlusal relationship. Carefully planned-restorative treatment in accordance with changed occlusal relationship is also required in the same context. Instead of taking changes in oral tissue as only a consequence of ageing, it is vital to educate patient and his or her guardian, assuring maintenance of oral hygiene and regular dental check-up are of utmost importance for improved oral health.