• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.203-208
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• 2008

Recently, high-rise building structures connected by a sky-bridge are frequently constructed. To predict accurate dynamic responses of structures connected a sky-bridge, time history analysis is required. Repetitive analyses are required in the design process. If the entire structure model is employed in the repetitive time history analysis, it would take a lot of computational time and engineers' efforts. Therefore, an equivalent model for high-rise building structures connected by a sky-bridge was proposed in this study. The proposed model consists of cantilever having original structure's stiffnesses and masses. Based on the analytical results, it has been shown that the equivalent model can reduce the analysis time and provide similar seismic responses to the original model.

• Journal of Preventive Medicine and Public Health
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• v.22 no.2 s.26
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• pp.189-196
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• 1989

In January 1988, district medical insurance plan was executed on a national scale in Korea. We conducted an evaluation of the impact of execution of district medical insurance plan on number of hospital patients: number of outpatients; and occupancy rate. This study was carried out by Box-Jenkins time series analysis. We tested the statistical significance with intervention component added to ARIMA model. Results of our time series analysis showed that district medical insurance plan had a significant effect on the number of outpatients and occupancy rate. Due to this plan the number of outpatients had increased by 925 patients every month which is equivalent to 8.3 percents of average monthly insurance outpatients in 1987, and occupancy rate had also increased by 0.12 which is equivalent to 16 percents of that in 1987.

• Journal of the Korean Institute of Gas
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• v.5 no.1
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• pp.21-28
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• 2001

Expert system for automating HAZOP analysis of batch processes In contrast with continuous processes must consider the discrete variables such as time and sequence. So in this study, we have developed the expert system for automating HAZOP analysis of batch processes to analyse time and sequence on the basis of the relation between discrete variables and continuous ones. Because these variables can not be explained by the method used in the HAZOP analysis of continuous processes. The proposed expert system have been discussed on a Latex batch process to evaluate its effectiveness.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.1
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• pp.135-141
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• 1999

Recently, advance signal analysis which is called "Time-Frequency Analysis" has been developed. Wavelet and Wigner Distribution are used to the method. Wavelet transform(WT) is applied to time-frequency analysis of waveforms obtained by an ultrasonic pulse-echo technique. The Gabor function is adopted as the analyzing wavelet. Wavelet analysis method is an attractive technique for evolution of material characterization evoluation. In this paper, the feasibility of suppression of ultrasonic background noise signal using WT has been presented. These results suggest that ultrasonic background noise ginal can be suppressed and enhanced even for SNR of 20.8 dB. This property of the WT is extremely useful for the detecting flaw echos embedded in background noise.und noise.

• Journal of Power System Engineering
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• v.10 no.2
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• pp.89-92
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• 2006

In this study, the pressure vessel piping with corrosion used during long term were investigated from the time-frequency analysis method. The damage of piping could be evaluated the attenuation factor by ultrasonic parameters such as center frequency and echo waveform. Based on NDE analysis by time-frequency analysis method, it should also be possible to evaluate from various damages and defects in piping members.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.304-309
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• 2003

A new modal analysis method for rotor systems with periodically time-varying parameters is proposed. The essence of method is to introduce modulated coordinates to derive the equivalent time-invariant equation. This paper presents a modal analysis method using modulated coordinates fur general rotors, of which rotating and stationary parts both possess asymmetric properties. The equation of motion with time-varying parameters is transformed to an infinite order matrix equation with the time-invariant parameters. A theory of modal analysis for the system is presented with the infinite order equation and a couple of reduced order equations. A numerical example with simple asymmetric rotor is provided to demonstrate the effectiveness of the proposed method

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.290-295
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• 2004

In this study, the pressure vessel piping with corrosion used during long term were investigated from the time-frequency analysis method. The damage of piping could be evaluated the attenuation factor by ultrasonic parameters such as center frequency and echo waveform. Based on NDE analysis by time-frequency analysis method, it should also be possible to evaluate from various damages and defects in piping members.

• Nuclear Engineering and Technology
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• v.55 no.7
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• pp.2712-2722
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• 2023

For an accurate and efficient time-dependent Monte Carlo (TDMC) neutron transport analysis, several advanced methods are newly developed and implemented in the Seoul National University Monte Carlo code, McCARD. For an efficient control of the neutron population, a dynamic weight window method is devised to adjust the weight bounds of the implicit capture in the time bin-by-bin TDMC simulations. A moving geometry module is developed to model a continuous insertion or withdrawal of a control rod. Especially, the history-based batch method for the TDMC calculations is developed to predict the unbiased variance of a bin-wise mean estimate. The developed methods are verified for three-dimensional problems in the C5G7-TD benchmark, showing good agreements with results from a deterministic neutron transport analysis code, nTRACER, within the statistical uncertainty bounds. In addition, the TDMC analysis capability implemented in McCARD is demonstrated to search the optimum detector positions for the pulsed-neutron-source experiments in the Kyoto University Critical Assembly and AGN201K.

• Journal of Families and Better Life
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• v.25 no.6
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• pp.121-131
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• 2007

The purpose of this study was first to reveal the factors of time management behaviors of college students. The second purpose was to examine the effects of those factors on the satisfaction of time management. The data were collected from 400 college students in Seoul by a self-administered questionnaire. Frequencies, Cronbach's alpha, Factor analysis, Pearson's correlation analysis and Multiple linear regression were conducted by SPSS WIN12.0. The major findings were as follows. First, factor analysis of 20 items on the time management behaviors related questions revealed six factors: establishment of standards, reality, overlapping, checking, adjusting and facilitating. Second, many factors such as facilitating, establishment of standards, reality, overlapping were significant in the regression analyses for the satisfaction of time management. Especially, establishment of standards and facilitating had high levels of effort on the satisfaction of time management. In combination, these results suggest that establishment of standards and facilitating are very important factors for high satisfaction of time management.

• Journal of Families and Better Life
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• v.22 no.5
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• pp.265-281
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• 2004

This study aims at studying dual-earner couple's household work time and life satisfaction in modern times. To reach this goal, dual-earner couple's variable of society and population, income for working hours, attitude of sex's role and working hours time were classified as individual variable of study model. In the end of 2000, positive analysis was completed through dual-earner couples' frequencies, percentage, means, paired-samples T Test, one-way ANOVA, duncan test, multiple regression and path analysis to 112 Korean couples in 'Research material for comparative analysis of family's time use in Korea and in the United States' performed by Lee, Ki-young, along with 3 person in the end of 2000. The time of household work performance at home at this stage is about 30 hours. 90% of 30 hours was given by housewife who was working for another job. In the aspect of dual-earner couple's life satisfaction, the life satisfaction is a little over the level of average. In variables couple's life satisfaction, wife's life satisfaction was additionally influenced by variable of wife's profession, age difference of couple, wife's household work time husband's household work time and wife's sex-role attitudes in oder. Husband's life satisfaction was perfectly influenced by his level of education, his household work time and wife's sex-role attitudes.