• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.63-65
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• 2007

Recently with increase consumption of electric power, the scale of the electric system becomes bigger and complex. Then, it is increasing the hardship in the operation of electric system and the continuance of stability. Especially, as the differences between demand and supply in electric power keeping low frequency oscillating attenuation from electric power have been very important in the continuance part of stability. The more control time of electricity system is getting faster with digitalization the more stability of electricity system is getting worse. As solutions of these problems, by establishing Power System Stabilizing Controller putting PSS output signal and putting damping to vibration of the rotor at generators's AVR in area where is oscillated, We are willing to contribute the electricity system by holding in generator output vibration.

• Journal of the Korean housing association
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• v.15 no.4
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• pp.65-74
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• 2004

As the advent of an aging society, housing for the elderly has been of great concern. Because the majority of the elderly prefers living in their own familiar homes rather than moving to new ones, this study is concerned with the ways use and maintenance of the existing houses from the viewpoint of their independent living. The data was analyzed with frequency, percentage, mean, correlation, and multiple regression by using the SPSS 10.0 for Windows. The findings from the study were: Needs for Affordance of interior design(AID) were required slightly above the average. Among the items of AID, physiological maintenance was the most demanding, and social facilitation, behavioral facilitation, and perceptual maintenance were sequentially followed in the level of needs. The elements that should be considered in housing environment plans for the elderly household ire: (a) use of slip-proof tiles for the floor of the bathroom, (b) installation of safety bars in the bathroom, and (c) installation of emergency buttons. It also turned out that educational levels and health status were the most significant factors on the needs for AID.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.10 no.1
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• pp.37-43
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• 2014

Nuclear power plants(NPPs) are consisted of power production functions and safety functions preventing leakage of radiation. Operators working in NPPs shall maintain these functions during an operation period through various activities such as improvement & modification, corrective maintenance, preventive maintenance and surveillance test. According to the performance of these work activities, there are configuration changes in NPPs systems. Its changes cause the increase of safety risks(CDF) and plant trip risks. Recently, the importance of risk management is increasing gradually in the operation process of NPPs. Therefore, this paper presents the work management methods using the various risk monitoring systems during power operation and overhaul period. Also this paper suggests the optimum application ways of risk systems for work management.

• Journal of muscle and joint health
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• v.23 no.3
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• pp.206-213
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• 2016

Purpose: The aim of this study was to identify the closeness, self-esteem and intention of exercise maintenance in the elderly participants of the BeHaS exercise program. Methods: Thirty-one elderly participated in the BeHaS exercise program which held 1 hour a week for 8 weeks. Data were collected by self-report questionnaires. Analysis of data was done using UCINET 6.0 for closeness and SPSS 22.0 program for frequency and Wilcoxon signed rank test. Results: The score of closeness, self-esteem and intention of exercise maintenance in pretest were significantly higher than those of posttest relatively(p<.001, p=.040, p=.007). Conclusion: These findings suggest that the BeHaS exercise program for elderly can be effective nursing care to improve closeness, self-esteem and intention of exercise maintenance.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1308-1314
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• 2008

In this paper, Seoulmetro that is the first operation organization which operates a city railroad rolling-stock maintenance RIMS(rolling stock information maintenance system) collected and analyzed a light maintenance data and introduced time a series analysis technique to find the way how to contribute to a use efficiency improvement of a city railroad. The purpose of time a series analysis is to remove a seasonal change including data and to check an irregular fluctuation. First of all, a collection range of the data comes under a light maintenance, however it needs a data of more than 3 years to check the seasonal change. We put a study for an accumulated scope that the data satisfy a period like this and are able to extend a range of the study when time flys forward. The data used for study is filtered using a movement average method after passing proper selection working and is solved with a method which looks for season index. Using the season index that was getten in here, we predict a light working frequency, if it has an irregular change, we will contribute it to a city railroad a use efficiency improvement and establish the cause by carrying out prevent maintenance in advance.

• Journal of Korean Association for Spatial Structures
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• v.16 no.2
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• pp.39-45
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• 2016

Membrane structure is a system that is stabilized by maintaining a tensile state of the membrane material that originally cannot resist the bending or pressure. Also, it is a system that allows the whole membrane structure to bear external loads caused by wind or precipitation such as snow, rain and etc. Tension relaxation phenomenon can transpire to the tension that is introduced to the fabric over time, due to the innate characteristics of the membrane material. Thus, it is important to accurately understand the size of the membrane tension after the completion of the structures, for maintenance and management purposes. The authors have proposed the principle of theoretically and indirectly measuring the tension by vibrating the membrane surface with sound waves exposures against the surface, which is compartmentalized by a rectangular boundary, and by measuring the natural frequency of the membrane surface that selectively resonates. The authors of this paper measured the tension of preexisting membrane structure for its maintenance by using the developed portable measurement equipment. Through analyzing the measurement data, the authors review the points that should be improved and the technical method for the new maintenance system of membrane tension.

• Child Health Nursing Research
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• v.18 no.3
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• pp.135-142
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• 2012

Purpose: The purpose of this study was to examine the effects of structured nursing intervention for caregivers on maintenance of intravenous (IV) infusions in infants. Methods: The structured nursing intervention was developed through the processes of interviews with nurses from pediatric wards. To identify the effects of the developed nursing intervention, a non-synchronized non-equivalent control group pretest-posttest design study was conducted with caregivers from the pediatric ward from a hospital in Seoul. Of 100 admitted infants, 50 caregivers were assigned to the intervention group and received the structured nursing intervention for maintenance of intravenous infusions in infants. The others were assigned control group and received routine care. Data were collected on patient factors, IV insertion factors, treatments, and IV related complications. The form developed for the structured nursing intervention was used by staff nurses. Results: Compared to the control group, IV insertion frequency in experimental group infants was significantly lower and IV related complications decreased (p<.05). Conclusion: These results suggest that the structured nursing intervention for caregivers on maintenance of intravenous infusions may have effects on maintenance of intravenous infusions in infants, and decreasing IV related complications. This nursing intervention can be used to improve IV related problems of admitted infants.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.2
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• pp.23-34
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• 2021

Cable was targeted for cable, which is a main material of cable-stayed bridges that have high frequency of use at home and abroad and many future construction plans. First of all, experiments were conducted on temperature loads that were permanently used due to changes in temperature of cables and changes in air temperature, taking into account changes in normal fat. The dynamic characteristics of cables were compared and analyzed by applying various systems to change dynamic characteristics by applying temperature change of cables. Comparing and analyzing the dynamic characteristics of cables, the acceleration, frequency and tension of cables due to temperature rise tended to decrease, the degree of influence of displacement of cables was analyzed, and the results of the mode characteristics of cables were analyzed. In particular, the correlation of cable acceleration, natural frequency, and tension due to changes in cable temperature showed that the cable tension is highly sensitive to acceleration and natural frequency.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.6
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• pp.95-104
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• 2006

The presence of cavitations under pavements or behind tunnel linings of concrete is likely to result in collapse. One method of detecting such voids by non-destructive means is low frequency type radar(GPR). By the way, the size and thickness of small cavitation can't be detected by the present radar technology with low frequency and low resolution when it apply to civil structures like that. To overcome these problems and limitations, this study aims to develope and propose a new analysis method for estimating the depth, cross-sectional size and thickness of cavitations using low frequency radar. A new proposed method is based on the experiments that are carried out for analyzing the correlation between the measurement values(the amplitudes of radar return) of low frequency radar and various type of cavitations. In this process, the threshold value for radar image processing which aims to represent only cavitations to be fitted size can be obtained. As the results, it is clarified that a proposed method has a possibility of estimating cavitation depth, size and thickness with good accuracy in laboratory scale.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.10 s.175
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• pp.80-89
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• 2005

In this paper, time-frequency analysis using wavelet packet transform and advanced-MDSA (Multiple Dimensional Spectral Analysis) which based on wavelet packet transform is applied fur fault source identification and diagnosis of early detection of fault non-stationary sound/vibration signals. This method is analyzing the signal in the plane of instantaneous time and instantaneous frequency. The results of ordinary coherence function, which obtained by wavelet packet analysis, showed the possibility of early fault detection by analysis at the instantaneous time. So, by checking the coherence function trend, it is possible to detect which signal contains the major fault signal and to know how much the system is damaged. Finally, It is impossible to monitor the system is damaged or undamaged by using conventional method, because crest factor is almost constant under the range of magnitude of fault signal as its approach to normal signal. However instantaneous coherence function showed that a little change of fault signal is possible to monitor the system condition. And it is possible to predict the maintenance time by condition based maintenance for any stationary or non-stationary signals.