• Earthquakes and Structures
• /
• v.25 no.1
• /
• pp.69-78
• /
• 2023

Life-cycle performance analysis of a reinforced concrete box section bridge was generated. Moreover, Monte Carlo simulation with important sampling (IS) was used to simulate the bridge material and load uncertainties. The bridge deterioration model was generated with the basic probabilistic principles and updated according to the measurement data. A genetic algorithm (GA) with the response surface model (RSM) was used to determine the deterioration rate. The importance of health monitoring systems to sustain the bridge to give services economically and reliably and the advantages of fiber-optic sensors for SHM applications were discussed in detail. This study showed that the most effective loss of strength in reinforced concrete box section bridges is corrosion of the reinforcements. Due to reinforcement corrosion, the use of the bridge, which was examined, could not meet the desired strength performance in 25 years, and the need for reinforcement. In addition, it has been determined that long-term health monitoring systems are an essential approach for bridges to provide safe and economical service. Moreover the use of fiber optic sensors has many advantages because of the ability of the sensors to be resistant to environmental conditions and to make sensitive measurements.

• Journal of Korean Academy of Fundamentals of Nursing
• /
• v.26 no.3
• /
• pp.197-209
• /
• 2019

Purpose: This study was done to examine good death awareness, attitudes toward advance directives (ADs), and preference for care near the end-of-life (PCEOL) of hospitalized elders in long-term care hospitals. Relevant characteristics were investigated as well as correlation of the variables. Methods: This descriptive research study involved 161 hospitalized elderly patients in long-term care hospitals. A self-report questionnaire was used to measure Good Death Scale, ADs Survey, PCEOL Scale, and general characteristics. Collected data were analyzed using descriptive statistics, t-test, ANOVA, and Pearson correlation with SPSS/WIN 23.0. Results: In terms of good death awareness, a significant difference was observed; in according to age (F=3.35, p=.037), payer of treatment costs (F=3.98, p=.021), mobility (F=3.97, p=.021), heard discussion about ADs (t=-3.89, p<.001), and willing to complete ADs (t=2.12, p=.036). As far as attitudes toward ADs, the participants presented significant difference depending on religion (t=2.38, p=.018), average monthly income (F=3.91, p=.022), duration of hospital admission (F=5.33, p=.006), person to discuss ADs (t=-2.76, p=.006). On PCEOL, there was a significant difference, depending on religion (t=-3.59, p<.001) and perceived health status (F=3.93, p=.022). Finally, as for how the variables were related to each other, good death awareness and attitudes toward ADs had a weak positive correlation with PCEOL. Conclusion: To help seniors staying in nursing homes face a good death and enjoy autonomy, there should be educational and support systems that reflect each individual's sociodemographic characteristics so that the seniors can choose what kind of care they want to receive near the end-of-life.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.48 no.8
• /
• pp.581-588
• /
• 2020

The aging characteristics of exploding foil initiator (EFI) are studied. In order to observe the aging characteristics, the main components of the exploding foil initiator were classified and the failure mechanism was defined. The aging characteristics were defined in terms of power and sensitivity, and the accelerated aging test plan was established based on the activation energy calculated by HFC (Heat Flow Calorimetry) and Arrhenius theory. The performance variation was observed using the sensitivity test (Neyer test) and power test (Dent test) for the aged samples. The aging characteristic was observed on the mean exploding point of the sensitivity test, but long-enough life span was predicted considering the related specification.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.18 no.3
• /
• pp.267-274
• /
• 2015

It is necessary to both analyze root-cause of non-conformance of effective illumination time to the specification, and estimate the storage lifetime for 81 mm illuminating projectile stockpiled over 10 years. In this paper, aging mechanism of magnesium flare material due to long-term storage was supposed, and two-stage tests, pre-test and main test based on accelerated degradation tests were performed. Field storage environment of moistureproof was set up, and illumination times in the accelerated degradation tests for temperatures 60 and $70^{\circ}C$ were measured. Then, storage reliability of the projectile was estimated through analyzing the measured data and applying distribution-based degradation models to the data. The $B_{10}$ life by which 10 % of a population of the projectiles will have failed at storage temperature of $25^{\circ}C$ was estimated about 7 years.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.23 no.1
• /
• pp.9-14
• /
• 2019

Hydroxy-terminated polybutadiene (HTPB) propellants of solid rocket motors age differently under different storage temperatures. The shelf life of a solid rocket motor depends on the aging ratio of the HTPB propellant; it can be estimated through the viscoelastic properties by an aging test. This study analyzed the initial and natural aging properties during long-term storage. The initial properties were obtained from characterization and accelerated test results. The test results were obtained by analyzing the strain on cylindrical grains when a thermal load was applied.

• Journal of the Korean Institute of Gas
• /
• v.27 no.2
• /
• pp.71-78
• /
• 2023

In general, electric submersible pumps (ESPs), which have an average life of 1.0 to 1.5 years, experience a decrease in performance and a reduction in life of the pump depending on oil and gas reservoir characteristics and operating conditions in wells. As the result, the failure of ESP causes high well workover costs due to retrieval and installation, and additional costs due to shut down. In this study, a flow loop system was designed and established to predict the life of ESP in long­term operation of oil and gas wells, and the life cycle data of ESP from the time of installation to the time of failure was acquired and analyzed. Among the data acquired from the system, flow rate, inlet and outlet temperature and pressure, and the data of the vibrator installed on the outside of ESP were analyzed, and then the performance status according to long-term operation was classified into five stages: normal, advice I, advice II, maintenance, and failed. Through the experiments, it was found that there was a difference in the data trend by stage during the long­term operation of the ESP, and then the condition of the ESP was diagnosed and the failure of the pump was predicted according to the operating time. The results derived from this study can be used to develop a failure prediction program and data analysis algorithm for monitoring the condition of ESPs operated in oil and gas wells.

• Journal of Korean Academy of Nursing
• /
• v.13 no.2
• /
• pp.58-69
• /
• 1983

This study on stressful life events and coping methods of hypertensive and nonhypertensive patients was applied to people who was divided into two groups from April 5 to March 10, 19 83. One is hospitalized patients in medical wards of three university hospital in Seoul. The other is inhibitants in two Dongs of Seoul. This study compared the number and seversity of stressful life events reported by hypertensive and nonhypertensive patients, indentified coping methods used by the two groups and explored the relationship between stressful life events and coping methods. Two instruments are used in this study. The first one to measure stressful life events, is Holmes ＆ Rahe (1967)'s S.R.R.S. (Social Readjustment Rating Scale). Which is translated & am-ended. So that it consists of 46 items. The second one is for evaluating coping method. It consists of f items amended through preliminary test after consideration of related literature review and survey on the basis of Bell (1977)'s‘18-item-Questionnaire.’The materials were analyzed by S.P.S.S. (Statistical Package for the Social Science) program-The results of analysis were as follows: 1. There were no significant difference in the number and severity of stressful life events reported by hypertensive and nonhypertensive patients (p>.05). 2. There were significant difference in use of short-term coping methods (p<.01) and long-term coping methods (p<.05).

• Journal of dental hygiene science
• /
• v.14 no.3
• /
• pp.379-389
• /
• 2014

This study intended to examine the health status and quality of life among the elderly patients who stayed in geriatric hospitals for a long period of time. The study involved 222 elderly who were older than 65-year-old, an oral examination was conducted in 10 geriatric hospitals located in the metropolitan area and Chungcheong-do. Cross-tabulation, one-way ANOVA, t-test, and Stepwise multiple regression were performed for analysis. The average number of teeth among the subjects was 11.22 and that of dental caries was 1.17. Also, the average number of teeth mobility was 0.93 and halitosis was detected among 81.9%. Only 29.70% reported absence or a kind of systemic disease and 70.31% of the subjects was shown to have more than two kinds of complex disease. In addition, 87.8% of the subjects had depression and among them, 55.40% showed serious depression. The average score on quality of life was 2.62 points and as for the related factors, the number of remaining teeth and dental caries were counted along with care grade, hospitalization period, and age. According to such results, the oral health status among the elderly patients staying long in geriatric hospitals were not good in general; also they showed high level of systemic disease and depression and low quality of life.

• Journal of Families and Better Life
• /
• v.11 no.1
• /
• pp.107-118
• /
• 1993

A dimension of well-being economic security was analyzed and compared with economic adequacy. Again it was tested whether two indicators of economic security(short-term vs. long-term) yield same distribution across all household groups. Economic Security was defined as the household ability to sustain a given level of consumption in the case of economic emergency; specifically loss of income. Measure of 8 different kinds of economic security were constructed from household net worth including and excluding home equity. Data were taken from the 1988 U.S. Consumer Expenditure Survey and 2148 households were selected to test hypotheses concerning the economic security of American households Empirical results showed a very low level of economic security in general. The first hypothesis that distribution of economic adequacy and economic security are same across all population groups was rejected. On the average security measure rather than adequacy measure was favor to white female-headed households and households who have old and highly educated house-holder. The second hypothesis that the indicators of long-term and short-term economic security yield the same results across all household was not rejected. In general the level of economic security was relatively higher when long-term indicator was used than short-term indicator was however the direction and relative size of effect of income and each control variable was almost same.

• Proceedings of the KIEE Conference
• /
• 2002.11d
• /
• pp.157-159
• /
• 2002

In order to obtain reliability and extend life of GAS Voltage Transformer in GIS, it has to prevent aging by overvoltage considered to insulation characteristics of insulating material. This paper describes some characteristics of V-T characteristics and partial discharges.