• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1989년도 추계학술대회 논문집 학회본부
• /
• pp.407-410
• /
• 1989

Optimizing transient response for both tracking reference signals and disturbance rejection is determined by the poles and zeros of the transfer function. Thus, optimal pole assignment and how should weighting matrix for the performance index be chosen is very important to achieve optimum transient response. This paper focus its attention on the choosing and analysis of weighting matrix for optimum pole assignment. Optimum pole assignment is defined for linear time-invariant continuous systems.

• Journal of Korean Biological Nursing Science
• /
• 제20권3호
• /
• pp.187-195
• /
• 2018

Purpose: The purpose of this study was to identify associations among the sleep disturbance, fatigue, job stress, and blood and body fluid (BBF) exposure of shift-work nurses. Methods: A total of 299 shift-work nurses from two tertiary hospitals were enrolled in this study. We used the Insomnia Severity Index (ISI), and the Fatigue Severity Scale (FSS), and the Korean Occupational Stress Scale-Short Form (KOSS-SF) to evaluate sleep disturbance, fatigue, and job stress, respectively. The data were analyzed using t-test or chi-squared test and Logistic regression analysis using the SPSS 23.0 program. Results: We found that 43.8% of participants reported BBF exposure over the past year. Splash or exposure to broken skin of BBF were most frequent (56.9%), and followed by needlestick injuries (30.4%) and sharp injuries (12.8%). Age, hospital, working period, level of stress, sleep disturbance ($ISI{\geq}15$), fatigue (FSS $score{\geq}4$), job demand and organizational climate subset in KOSS-SF were significantly associated with BBF exposure in shift-work nurses. In multivariate analysis after adjusting age and hospital, the risk factors of BBF exposure in shift-work nurses were the level of stress and fatigue (FSS $score{\geq}4$). Conclusion: Fatigue and job stress were related to BBF exposure in shift-work nurses. Our results suggest that management of sleep disturbance, fatigue, and high job stress in shift-work nurses is needed to reduce risk of BBF exposure.

• 한국전기전자재료학회논문지
• /
• 제28권11호
• /
• pp.748-751
• /
• 2015

Sound Masking System technology as by sound the same on all bands and artificially generates a constant sound shield People want to hear or recognize the people with the noise generated from the interior of the way. Prevent hearing or prevent recognition by using the technology to control the audible frequency band Continue to emit constant and uniform shielding sound audible frequency band Even the security content of speech (20 Hz~20 KHz). That interception laser eavesdropping, internal solicitations, during recording Or delay the decoding was a result of the effect of interference calculated Experience noise disturbance index is applied around the Stress Index is the average index is 10.16 was a luxury for the average index is then applied to the index 3.07 Noise is significantly lower stress level has improved noise conditions.

• Journal of Preventive Medicine and Public Health
• /
• 제29권3호
• /
• pp.609-616
• /
• 1996

This study was conducted to evaluate the degree of stress state and the risk factors related to in 967 white collar workers and 275 blue collar workers by using Psycosocial Well-being Index. The results obtained were as follows : 1. In the white collar workers and blue collar workers, young age, low education and low income groups had high scores of stress, while in white collar workers, female had high scores of stress but in blue collar workers, male had high scores of stress. 2. According to psychosocial well-being index, mild stress sto were 73.9% and 53.1%, high risk stress state were 8.9% and 44.4%, and healthy state were 17.2% and 2.6% in white collar and blue collar workers respectively. 3. The total stress score was highly associated with the factors of depression, social performance and self-confidence, general well-being and vitality, and sleeping disturbance and anxiety in order. 4. In reliability test of stress factors, Cronbach's $\alpha$ coefficients of depression, social performance and self-confidence, general well-being and vitality, and sleeping disturbance and anxiety were 0.89, 0.81, 0.79, and 0.74 respectively. In conclusion, it suggested that age, sex, marital status, income, education, sleeping time, smoking and exercise habit were associated with stress score, all of the above factors should considered to occupational health.

• 산업기술연구
• /
• 제34권
• /
• pp.53-59
• /
• 2014

The single regression method was used to analyze the correlationship between the compression index with mechanical properties for reclaimed marine clays in the southern coast of Korea. As results of performing regression analysis for 200 samples about reclaimed marine clays in the southern coast of Korea, linear regression lines between compression index and natural water content, void ratio in situ, and liquid limit respectively wer obtained. The changed properties of soil due to disturbance during dredging and reclaiming could be investigated by comparing with the existing empirical correlation equations for the original ground where dredging was performed. These regression equations might be rationally used in the preliminary evaluation of settlement of dredged and reclaimed marine clayey ground in the southern coast of Korea.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2004년도 춘계학술대회 논문집
• /
• pp.90-94
• /
• 2004

Among various modern control theories, PID control has been well used for several decades. PID algorithms needs son tuning methods are used for selecting PID parameters. But in some cases various kinds of performance indices are used instead of well-known tuning rules, and so variable type of performance index must be tested so that controllers, output characteristics and disturbance rejection property meets some specifications. In this paper, linear conbinational type of performance using error signal, time, control input and robustness is used to the PID control of air conditioning system. By the 2 DOF PID parmeters minimizing perfromacne index, controllers, output characteristics and robustness properties are analyzed. Simulations are done with MATLAB m file and mdl files.

• 대한임상검사과학회지
• /
• 제39권3호
• /
• pp.264-270
• /
• 2007

Obstructive sleep apnea syndrome (OSAS) is defined by sleep apnea with decreased oxygen saturation, excessive snoring with daytime sleepiness, and frequent awakening during the night time sleep. The present study was performed to investigate how apnea-hypopnea, that possibly causes breathing disturbance during sleep, can affect sleep pattern in patients with OSAS. We included 115 patients (92 men, 23 women) who underwent a polysomnography from January 2006 to May 2007. As the frequency of sleep apnea-hypopnea increases, the proportion of non-rapid eye movement (REM) sleep (p<0.001), and stage I sleep (p<0.001) increased, while that of stage II sleep (p<0.001), stage III and IV sleep (p<0.01), and REM sleep (p<0.05) decreased. Furthermore, sleep apnea-hypopnea was closely correlated with REM sleep (r=0.314, p<0.001), stage I sleep (r=0.719, p<0.001), stage II sleep (p=-0.342, p<0.05), stage III and IV sleep (r=-0.414, p<0.001), and REM sleep (r=-0.342, p<0.05). Stage I sleep could account for the 51% of the variance of apnea-hyponea. Our study shows sleep apnea-hypopnea affects sleep pattern in pattern with OSAS significantly, and the change of stage I sleep is the most important factor in estimating the disturbance of sleep pattern.

• Journal of Electrical Engineering and Technology
• /
• 제13권3호
• /
• pp.1110-1122
• /
• 2018

This paper proposes an alternative method to evaluate the effect of wind power to the power system stability with small disturbance. Alternatively, available techniques for stability analysis of a power system based on deterministic methods are less accurate for high penetration of wind power. Numerical simulations of random behaviors are computationally expensive. A stochastic stability index (SSI) is proposed for the power system stability evaluation based on the theory of stochastic stability and energy function, specifically the stochastic derivative of the relative well-defined energy function and the critical energy. The SSI is implemented on the modified nine-bus system including wind turbines under different conditions. A doubly-fed induction generator (DFIG) wind turbine is characterized and modeled using measured wind data from several sites in Thailand. Each of the obtained wind power data is analyzed. The wind power effect is modeled considering the aggregated effect of wind turbines. With the proposed method, the system behavior is properly predicted and the stability is quantitatively evaluated with less computational effort compared with conventional numerical simulation methods.

• Journal of Ecology and Environment
• /
• 제35권4호
• /
• pp.279-289
• /
• 2012

This study conducted a comparative analysis of benthic macroinvertebrate communities in the Fosu and Benya lagoons in Ghana, based on the anthropogenic effect on the two lagoons. Salinity, oxygen, temperature, conductivity, turbidity and pH were measured, invertebrate richness and species densities were determined. The AZTI Marine Biotic Index (AMBI) and multivariate statistics were used to determine the different responses of fauna to pollution. The fauna were categorized into five ecological groups based on the degree of tolerance of the different species to pollution: disturbance-sensitive species; disturbance-indifferent species, disturbance-tolerant species, second-order opportunistic species; and first-order opportunistic species. The Fosu Lagoon supported more pollution tolerant species, whereas the Benya Lagoon had more species that were sensitive to organic enrichment under relatively unpolluted conditions. Chironomus sp., which is adapted to virtually anoxic conditions, was the most abundant in the Fosu Lagoon whereas Nemertea sp. was the most abundant in the Benya Lagoon. The numerical and relative abundance (%) of all 7 taxa in the Fosu Lagoon was 1,359 and 92.35%, respectively. The numerical and relative abundance (%) of all 34 taxa in the Benya Lagoon was 2,459 and 87.52%, respectively. Expectedly, the level of dissolved oxygen in the less saline Fosu Lagoon was higher than that in the more saline Benya Lagoon. The reduced photoperiod and photosynthetic activities of aquatic plants might account for this trend. There is a need to implement comprehensive monitoring and management initiatives for sustaining the ecological health of coastal lagoons in Ghana in order to support the many people that depend upon these ecosystems for their livelihood.

• 한국조경학회지
• /
• 제26권2호
• /
• pp.240-250
• /
• 1998

This study is to have attempted to analyze the characteristics of the change in forest landscape pattern of Seoul for 18 years by grasping it through satellite image data on the forest area in Seoul where a rapid change according urbanization and industrialization is going on. On the basis of Landsat MSS data- satellite image data, this writer analyzed the change in the number and size of patch and the mean edge length of each forest land, and the index of patch shape by each year from a landscape -ecological point of view. The results are as follows; First, in the pattern change of the forest patch of Seoul, the highest patch fragmentation area is the forest of the Yangchon-gu district where is decreasing it forest area by 654ha, 511ha, 495ha, 402ha each year from its total size of 742ha in 1979. Second, the change tendency shows that the average forest size decreased at 552.58ha in 1983, 435.03ha in 1988, 396.23ha in 1992, and 379.96ha in 1996. And analysis showed that even in the number of patches, the forest fragmentation phenomenon was presenting by the increase of development disturbance. Third, the mean edge by year was longest at 23,385m in 1979, but it is decreasing continuously. This shows the regular and artificial uniformity of forest landscape by disturbance-effect increase of the built-up development and shows low portion against edge effect by the time-series change like 1979>1983>198>1992>1996. Finally, in the analysis of a shape index indicated by ratio of size and edge, total averages were 2.56, 2.33, 2.17, 2.14, 2.14 each year, so that it is considered that the disturbance and ecological health status against forest landscape can be grasped according to being examined as 1979>1983>1988>1992, 1996 by the time-series change of the landscape.