• Journal of Electrical Engineering and Technology
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• 제13권3호
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• pp.1355-1362
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• 2018

In order to obtain a better understanding of the ageing process of the field composite insulators, it is necessary to explore a quantitative-valuation method for the aging state evaluation. And the linear relationship between volume resistivity and temperature is proposed. In this paper, the composite insulators with different lengths of operating lives from two manufacturers were tested. The relationship between trap characteristics and volume resistivity-temperature characteristics were analyzed based on Thermal Stimulated Current (TSC), volume resistivity-temperature test, Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Furthermore, the application of trap characteristics in the quantitative evaluation of aging state of composite insulators was discussed. The results showed that there was a general negative correlation between the relative variation ratio of trap charges and the volume resistivity-temperature characteristics. Meanwhile, the physicochemical properties would change with the aging time, which would result in the increasing of electron traps. Combined with the TSC and volume resistivity test results, the trap characteristic thresholds which indicated the serious age of the composite insulators had been proposed.

• 열처리공학회지
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• 제8권1호
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• pp.53-64
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• 1995

A study was made to characterize the microstructures and mechanical properties of the base metal and the heat-affected zone(HAZ) in Cu-bearing HSLA-100 steel. The Gleeble thermal/mechanical simulator was used to simulated the weld HAZ. The relationship between microstructure and toughness of HAZ was studied by impact test, O. M, SEM, TEM, and DSC. The toughness requirement of military specification value was met in all test temperatures for the base metal. The decrease of HAZ toughness comparing to base plate is ascribed to the coarsed-grain and the formation of bainite. Obliquely sectioned Charpy specimens show that secondary crack propagate easily along bainite lath. Improved toughness(240J) at HAZ of $Tp_2=950^{\circ}C$ is due to the fine grain, and reasonable toughness(160~00J) in the intercritical reheated HZA is achieved by the addition of small amount of carbon which affects the formation of "M-A". Cu precipitated during ageing for increasing the strength of base metal is dissolved during single thermal cycle to $1,350^{\circ}C$ and is precipitated little on cooling and heating during subsequent weld thermal cycle. Thus, the decrease of toughness does not occur owing to the precipitation of Cu.

• Journal of Preventive Medicine and Public Health
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• 제56권2호
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• pp.164-171
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• 2023

Objectives: Sarcopenia has emerged as a significant aging-related disease that affects many facets of societal-level and patient-level public health. This study analysed knowledge of sarcopenia and associated socio-demographic factors among the general public of Malaysia in order to effectively improve its prevention and countermeasures. Methods: A cross-sectional online survey was conducted in Selangor, Malaysia, using Google Forms among 202 Malaysian adults from January 1, 2021 to March 31, 2021. Descriptive statistics were used to analyse the socio-demographic characteristics and knowledge scores. The continuous variables were evaluated using the independent t-test, Mann-Whitney test, and one-way analysis of variance test. The Spearman correlation coefficient was employed to determine the correlation between socio-demographic characteristics and knowledge score levels. Results: The final analysis included 202 participants. The mean±standard deviation age was 49.03±12.65. Only 6.9% of participants had good knowledge of sarcopenia and were aware of sarcopenia's characteristics, consequences, and treatments. Post-hoc comparisons using the Dunnett T3 test showed statistical significance in mean knowledge score and age group (p=0.011) and education level (p≤0.001). The Mann-Whitney test revealed that gender (p=0.026) and current smoking status (p=0.023) significantly influenced knowledge scores. Conclusions: The general public's knowledge of sarcopenia was found to be poor to moderate and associated with age and education status. Therefore, education and interventions by policymakers and healthcare professionals to improve public knowledge of sarcopenia in Malaysia are needed.

• The Journal of Advanced Prosthodontics
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• 제6권4호
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• pp.272-277
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• 2014

PURPOSE. The purpose of this study was to investigate the impact of different surface treatment methods and thermal ageing on the bond strength of autopolymerizing acrylic resin to Co-Cr. MATERIALS AND METHODS. Co-Cr alloy specimens were divided into five groups according to the surface conditioning methods. C: No treatment; SP: flamed with the Silano-Pen device; K: airborne particle abrasion with $Al_2O_3$; Co: airborne particle abrasion with silica-coated $Al_2O_3$; KSP: flamed with the Silano-Pen device after the group K experimental protocol. Then, autopolymerized acrylic resin was applied to the treated specimen surfaces. All the groups were divided into two subgroups with the thermal cycle and water storage to determine the durability of the bond. The bond strength test was applied in an universal test machine and treated Co-Cr alloys were analyzed by scanning electron microscope (SEM). Two-way analysis of variance (ANOVA) was used to determine the significant differences among surface treatments and thermocycling. Their interactons were followed by a multiple comparison' test performed uing a post hoc Tukey HSD test (${\alpha}=.05$). RESULTS. Surface treatments significantly increased repair strengths of repair resin to Co-Cr alloy. The repair strengths of Group K, and Co significantly decreased after 6,000 cycles (P<.001). CONCLUSION. Thermocycling lead to a significant decrease in shear bond strength for air abrasion with silica-coated aluminum oxide particles. On the contrary, flaming with Silano-Pen did not cause a significant reduction in adhesion after thermocycling.

• 한국구조물진단유지관리공학회 논문집
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• 제20권4호
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• pp.111-119
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• 2016

반발경도법과 복합법에 의한 현장비파괴 시험과 코어강도의 평가는 노후화된 구조물의 상태평가를 위하여 가장 효과적인 방법이다. 그러나 비파괴 시험방법의 불확실성과 함께 재료의 재령, 탄산화와 코어채취시의 물리적 손상 등에 의하여 현장강도 추정시의 정밀도를 낮추는 요인으로 작용하게 된다. 본 연구에서는 106개 교량에서 수집된 268개의 비파괴시험결과와 코어압축강도 결과를 사용하여 현장 압축강도 추정방법을 제시하고자 하였다. 코어강도의 신뢰도를 높이기 위하여 수정계수를 적용하고자 하였으며, 노후콘크리트의 반발경도에 영향을 미치는 탄산화 또는 재령에 의한 수정계수를 적용하여 현장 강도 추정결과의 신뢰도를 높이고자 하였다. KISTEC의 제안 추정식과 수정계수를 적용한 경우 기존의 추정방법과 비교하여 신뢰도가 높아지는 것으로 나타났다.

• 대한금속재료학회지
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• 제48권2호
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• pp.122-132
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• 2010

Higher strength and fracture toughness of reactor pressure vessel steels can be obtained by changing the material specification from that of Mn-Mo-Ni low alloy steel (SA508 Gr.3) to Ni-Mo-Cr low alloy steel (SA508 Gr.4N). However, the operation temperature of the reactor pressure vessel is more than $300^{\circ}C$ and the reactor operates for over 40 years. Therefore, we need to have phase stability in the high temperature range in order to apply the SA508 Gr.4N low alloy steel for a reactor pressure vessel. It is very important to evaluate the temper embrittlement phenomena of SA508 Gr.4N for an RPV application. In this study, we have performed a Charpy impact test and tensile test of SA508 Gr.4N low alloy steel with changing impurity element contents such as Mn and P. And also, the mechanical properties of these low alloy steels after longterm heat treatment ($450^{\circ}C$, 2000hr) are evaluated. Further, evaluation of the temper embrittlement by fracture analysis was carried out. Temper embrittlement occurs in KL4-Ref and KL4-P, which show a decrease of the elongation and a shifting of the transition curve toward high temperature. The reason for the temper embrittlement is the grain boundary segregation of the impurity element P and the alloying element Ni. However, KL4-Ref shows temper embrittlement phenomena despite the same contents of P and Ni compared with SC-KL4. This result may be caused by the Mn contents. In addition, the behavior of embrittlement is not largely affected by the formation of $M_3P$ phosphide or the coarsening of Cr carbides.

• 보건교육건강증진학회지
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• 제31권3호
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• pp.51-61
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• 2014

Objectives: The purpose of this study was to identify the effects of job characteristics on smoking, and the mediating effects of job stress between job characteristics and smoking among elderly workers. Methods: This study employed data from the Korean Longitudinal Study of Ageing, and a total of 778 older workers were used for analysis. Current smoking status, job stress, job characteristics including physical job demands, job demands related to contents, working days, regularity of working hour, satisfaction with income, and sociodemographic factors were analyzed. Descriptive analysis, t-tests, chi-square test, multiple linear regression, and logistic regression were used for analysis. Results: Results showed that physical job demands and regularity of working hours were significant predictors of smoking of elderly workers. The higher level of physical job demands and regular working-hour increased the risk of smoking. Also, physical job demands, job demands related job contents, and income satisfaction directly impacted on job stress. However, job stress did not mediate the relationship between job characteristics and smoking. Conclusions: The findings suggest that smoking interventions for older workers should take into account job characteristics. Implications for practice and future study directions are discussed.

• 지역사회간호학회지
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• 제26권4호
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• pp.372-379
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• 2015

Purpose: This research was conducted to examine the successful aging and identify factors influencing successful aging in the Korean elderly. Methods: The subjects were 4,507 elders and data were collected from the 4th Korean Longitudinal Study of Ageing in 2012. The data were analyzed using frequencies, weighted percentage, ${\chi}^2$ test, and logistic regression. Results: The results of this study showed that 19.6% of the participants were categorized to successful aging. The domains of the absence of disease and disability and maintaining physical and mental functioning showed a high rate of achievement, while the domain of active engagement with life showed a low rate of achievement compared to others. Successful aging was influenced by gender, age, subjective economic status, subjective health status, and family support, particularly spouse's support. Conclusion: Intervention programs to increase the prevalence of successful aging are required. Especially programs for strengthening spouse's support and enhancing subjective health status are required.

• 기본간호학회지
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• 제6권2호
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• pp.211-227
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• 1999

This study was planned and carried out in an attempt to investigate health status and life style. Using a guidline developed by the researcher open-ended interviews were done with a hundred and sixty Korean elderly people, from April 17, through June 2, 1988. The data were analyzed by frequencies, means, percentile scores and Chisquare-test. Major health deviations identified are ; arthritis, blood pressure discrepancies, neuralgia, and powerlessness. Discomfort in relation to elimination(75%) and to rest-activity, especially to the activities of daily living(78%) are experienced ; 11% revealed to be in need of assistance from others. One or more sensory discrepancies are complained by 75% of the subjects. Only 20% of the subjects reported being satisfied with the life-time achievements. Factors revealed that 'descendants' were the major source of pleasure. Leisure hours were spent mostly 'watching TV' 'Healthy life', 'harmonious family life' and 'frequent communication with the family' were the three most frequent wishes towards their family members. 'Insurance for ageing', 'free health care', 'work', 'cultural facilities' and 'warm attention' were the request toward the society.

• 한국식품영양학회지
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• 제23권4호
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• pp.485-491
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• 2010

With an increase in the number of people suffering from ageing-related diseases in our rapidly aging society, interests in natural products such as maca(Lepidium meyenii), which has properties of enhancing cognition and sexual performance, have increased. This study was conducted to assess the effects of 7 weeks of maca extract supplementation(0.5~2.0 g/kg BW) on scopolamine-induced amnesia in mice and on sperm count in male mice. All doses of maca supplementation significantly protected against scopolamine-induced amnesia as determined by a Morris water maze, but not according to passive avoidance tests. Maca supplementation did not affect acetylcholinesterase activity in the whole brain, nor the testicular sperm count of male mice. This study suggests that maca may have some neuroprotective properties in mice, which will be further examined by future studies.