• Proceedings of the Korean Nuclear Society Conference
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• 1996.05c
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• pp.79-84
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• 1996

Small punch test was performed on CF8 duplex stainless steel aged at 370 and 400$^{\circ}C$ up to 5,000 h to evaluate the degree of the thermal aging embrittlement. At room temperature, the SP load-displacement curve was in a similar shape to those of ferritic steels and had a good reproducibility in spite of two-phase structure. The aging heat treatment resulted in a slight increase of the yield strength. As test temperature was lowered, the SP load showed a sudden drop followed by serrations before the SP specimen was fractured, resulting from the cracking of ferrite phase. The extent of thermal embrittlement was assessed in terms of the SP energy. Aging treatment at higher temperature led to a larger shift in the transition temperature and the corresponding change in the fracture mode. The main cause of the degradation was the embrittlement of ferrite phase. Additionally the phase boundary separation profoundly contributed to the degradation of the specimen aged at 400$^{\circ}C$.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.126-129
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• 2006

AC-plasma display panels were examined before and after the aging process to analyze the effect of the aging process. The gas analysis was done to detect the impurity gases out of the MgO film and phosphor by a residual gas analyzer. There were no differences found in the components. The MgO film was analyzed to find out the effect of an ion bombardment due to discharge. The surface roughness of the MgO film was different from regional groups due to the different degree of ion bombardments. XPS analysis showed that the 8 hour aging process was not sufficient to remove $Mg(OH)_2$ and $MgCO_3$ existed on the MgO surface. Photoluminescence measurement showed the small deterioration of blue and green phosphor.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.3
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• pp.45-54
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• 2000

Ignition transient is a. very rapid process lasting only in the order of 100 milliseconds and therefore it is difficult to measure all relevant ballistic properties. Numerical simulation is thus useful to quantify some of these hard to measure flow and ballistic properties. One-dimensional model was employed to study the effects of aging using simplified aging scenarios for both N-H sustainer and booster motors. Also the effects of newly designed igniter on the ignition of N-H sustainer was simulated. Radiation effects could be significant in terms of energy flux increase to the propellant surface and the energy exchange between the combustion gas itself. One dimension implementation of radiation showed significant effects for rear-mounted igniter. Implementation of radiation effects into 2-D axi-symmetric numerical model was completed and its effects on the N-H sustainer were examined. To have a reliable prediction of computer model on ignition transient, accurate chemical property data on the propellant and igniter gas are required. It was found that such property data on aged N-H motors are not available. Chemical aging model can be used to predict to some degree of accuracy effects of aging on chemical and mechanical properties. Such a model was developed, albeit 2-dimensional, to study migration of moisture through a representative solid rocket motor configuration.

• Journal of the Korean Solar Energy Society
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• v.37 no.5
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• pp.65-75
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• 2017

In this study, the change of heat loss due to the degree of deterioration of the XPS insulation in KEPCO's office buildings is analyzed. The acceleration aging test of the XPS insulation was carried out according to the test method A of KS M ISO 11561: 2009. The performance of the insulation was analyzed by applying it to the three - dimensional steady state heat transfer analysis program. The acceleration aging test of the XPS insulation, show that the thermal resistance performance decreased by 1.44% at the A regional headquarters, 0.85% at the B regional headquarters, 6.41% at the C branch office, 7.76% at the D regional headquarters, 8.51% at the E branch office, and by 8.54% at the F branch office respectively. Using simulation, we determined that the thermal resistance value of E branch office decreased by 8.04%, while its heat loss increased by 8.52%. At A regional headquarters, the thermal resistance decreased by 1.38%, and the heat loss increased by 1.51%. At D regional headquarters, these value are 6.82% and 7.17%, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05b
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• pp.82-86
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• 2004

This research is about the result of leakage current waveform about the situation of surface leakage current and environmental changes(Salt fog, clean fog and rain) by EPDM polymer insulators' amount of salt. The researcher presents the result of changing about fundamental harmonic, 3rd harmonic and 5th harmonic from starting point of supplying power to flashover. In this study, researched environmental affects (clean fog, salt fog and rain) about surface aging of polymer insulators and used frequency spectrum of leakage current waveform to develop the diagnostic technique of surface aging. When amount of salt contents changed, surface aging stage and the degree of aging (distortion factor) about 3rd and 5th harmonic waveform on low frequency harmonic wave. The distortion factor which is harmonic percentage about basic harmonic is important pointer to evaluate the surface condition of polymer insulators.

• Journal of the Ergonomics Society of Korea
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• v.26 no.2
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• pp.67-79
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• 2007

The objective of this study is to investigate a perceived discomfort and cause of Korean elderly in various activities such as work and leisure as well as in daily activities. 120 subjects (30 female and 30 male for each age: the young and elderly) participated in the interview type of questionnaire. Each participant answered to 41 items of activities of daily living. The examination of each item was progressed with 3 steps: whether to do the activity or not, degree of activity discomfort, and the reasons or causes of discomfort. Borg's CR10 scale is used to measure the degree of discomfort of daily activities. As a result, there are differences for the proportion of performers between two age groups, except for essential activities such as individual maintenance and housekeeping. The elderly complained about their daily activities more than the young did, and the degree of discomfort of women was significantly larger than that of men with aging. There are seven items, the mean degree of discomfort of which is over three points for the elderly, and they showed significant difference between two age groups. It was the important reason that physical capacities such as muscle strength and suppleness are declined. The results showed the characteristics of Korean elderly in the whole daily activities. These will be used to understand various life styles of them and to propose a field or direction of study related to the aging.

• Journal of Korean Public Health Nursing
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• v.11 no.1
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• pp.93-102
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• 1997

The study aimed at investigating the living time as well as disability degree of the elderly based on daily living acting capability and living activity degree. The survey was conducted through the home-visit interview during half month at july, 1996 by the students of nursing department who were previously trained. The survey targeted the elderly aged 65 years or more living at home in rural area. The study tried to utilize Activity Inventory(AI) made for examing health and disease, disability degree, and living acting degree of the elderly. Among the AI's, there are Physical Activity of Daily Living(PADL), Instrumental Activity of Daily Living(IADL), maximum daily activity scope, and physical and mental activity level of the elderly. The daily living time is surveyed physiologic time(sleeping, eating and grooming), labor time(occupation, housekeeping and farming) and leisure time(reading, sport hobby-life). Results of the study show that social activity degree of the elderly is found to be lower than that PADL, LADL, and daily living scope. It seems that the elderly suffer from inability in daily life with lower social activity degree. But the labour time of the daily living time is the most amount time in the targeted 361 elderlys through random sampling. Therefore postponement of the disability of aging should be devised to encourage the labour activity of the elderly.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.901-903
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• 1998

Crosslinked Degree is an important factor to determine dielectric property of crosslinked polyethylene(XLPE) used for the insulation material in power cables. Recently, though it is necessary to investigate electrical properties according to crosslinked degree as a part of the whole characterization of cable. it is not examined closely. In this study, crosslinked degree of samples were measured according to temperature and holding time of crosslinking, electrical tree characteristics of these samples were analyzed by crosslinked degree and applied temperature that was changed from normal temperature to operating temperature of power cables. As a result. when the crosslinked degree was low, dielectric properties were decreased and influence of temperature was increased. but the crosslinked degrees were high. initiation voltages of treeing were increased and dielectric properties were improved. It is proved that the optimum. crosslinked degree was one of most important factor for aging time and residual lifetime of power cable.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.3
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• pp.353-362
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• 2014

Purpose: The present study was aimed to investigate the change of higher-order aberrations induced by aging and the effect of myopic degree on the correlation between age and higher-order aberrations. Methods: The higher-order aberrations in 931 eyes aged from 20 to 60 were measured by using a LADARWave device employing Hartmann-Shack system to analyze the effect of myopic degree measured by manifest refraction test on higher-order aberrations. Results: Coma and vertical coma aberrations were significantly decreased by the increase of myopic degree while vertical astigmatic aberration was significantly increased. The correlations of age and coma, vertical coma, spherical, vertical trefoil, horizontal trefoil, vertical astigmatic, horizontal astigmatic and vertical tetrafoil aberrations depended on the myopic degree, except for horizontal coma and horizontal tetrafoil aberrations. Conclusions: It is suggested to consider the myopic degree for the refractive correction including the laser surgery based on the present result that higher-order aberrations are affected by the myopic degree.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.398-407
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• 2021

Firefighters (who are responsible for people's safety) have one of the jobs that are expected to have problems due to aging in the workforce. An increase in the average age of firefighters can lead to serious social problems. The aim of this study is to survey firefighters in Jeollanam-do about their awareness of aging in firefighters, and to propose a plan to prepare them for aging through investigation and analysis of work problems that may occur due to an aging workforce. The survey shows that the higher the age group, the higher the awareness of aging firefighters, and the higher the total work experience and internal/external work experience, the higher the awareness of aging. As a plan to solve various problems that may arise from aging in firefighters, regular operation of physical fitness promotion programs, field work, job rotation, and managerial measures (such as a change of position to an administrative department) are prepared, and drone or robot technology is used. These solutions include the introduction of applied high-tech technologies to firefighting activities, establishment of retirement management policies, and preparation of plans to revitalize the connection to private employment. In order to maximize the applicability of the field, government institutional plans and preparations are essential.