• Journal of Electrical Engineering and Technology
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• v.10 no.6
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• pp.2240-2248
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• 2015

The integration of the large-scale wind power brings great challenge to the stability of the power grid. This paper investigates and studies the fault on May 14, 2012 of the large-scale cascading trip-off of wind turbines in North China. According to the characteristics of the voltage variation, the fault process is divided into three stages: the pre-event stage, the critical stage before cascading, and the cascading stage. The scenes in the fault are reproduced, using the full-size actual power system model. Simulation models of double-fed induction generators (DFIGs) and SVCs including protection settings and controller strategies are carefully chosen to find out the reason of voltage instability in each stage. Some voltage dynamic that have never been observed before in the faults of the same kind are analyzed in detail, and an equivalent voltage sensitive dynamic model of DFIG is proposed for the fast computation. The conclusions about the voltage dynamics are validated by the actual PMU observation evidence.

• International Journal of Automotive Technology
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• v.5 no.3
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• pp.155-164
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• 2004

The direct injection gasoline spray-wall interaction was characterized inside a heated pressurized chamber using various visualization techniques, including high-speed laser-sheet macroscopic and microscopic movies up to 25,000 frames per second, shadowgraph, and double-spark particle image velocimetry. Two hollow cone high-pressure swirl injectors having different cone angles were used to inject gasoline onto a heated plate at two different impingement angles. Based on the visualization results, the overall transient spray impingement structure, fuel film formation, and preliminary droplet size and velocity were analyzed. The results show that upward spray vortex inside the spray is more obvious at elevated temperature condition, particularly for the wide-cone-angle injector, due to the vaporization of small droplets and decreased air density. Film build-up on the surface is clearly observed at both ambient and elevated temperature, especially for narrow cone spray. Vapor phase appears at both ambient and elevated temperature conditions, particularly in the toroidal vortex and impingement plume. More rapid impingement and faster horizontal spread after impingement are observed for elevated temperature conditions. Droplet rebounding and film break-up are clearly observed. Post-impingement droplets are significantly smaller than pre-impingement droplets with a more horizontal velocity component regardless of the wall temperature and impingement angle condition.

• Korean Journal of Adult Nursing
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• v.16 no.3
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• pp.452-459
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• 2004

Purpose: To investigate the effect of oral care either with normal saline or with tantum solution on the oral state of the patients in intensive care unit as well as the frequency of bacteria occurrence inside their oral cavities. Method: The study was performed from March thru May of 2003 on the nonequivalent control group non-synchronized quasi-experimental design. Forty subjects were selected for each group. The data were analyzed using the SPSS 10.0 Win. The pre-experimental homogeneity and post-experimental differences between the two groups were analyzed with t-test. Result: There was a significant difference in the oral cavity state between the experimental group that had used normal saline and the control group that had used tantum solution. Conclusion: Based on the results described above, it is considered that normal saline is more effective than the tantum solution for the oral care of the patients in intensive care unit.

• Carbon letters
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• v.12 no.4
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• pp.229-235
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• 2011

Isotactic polyacrylonitrile (PAN) with triad isotacticity of 0.53, which was determined by $^{13}C$ NMR, using dialkylmagnesium as an initiator, was successfully synthesized. Isothermal treatment of iso-PAN was conducted in air at 200, 220, 250 and $280^{\circ}C$. Structural evolutions and chemical changes were studied with Fourier transformation infrared and wide-angle X-ray diffraction during stabilization. A new parameter $CNF={I_{2240cm}}^{-1}/ ({I_{1595cm}}^{-1}+f^*{I_{1595cm}}^{-1})$ was defined to evaluate residual nitrile groups. Crystallinity and crystal size were calculated with X-ray diffraction dates. The results indicated that the nitrile groups had partly converted into a ladder structure as stabilization proceeded. The rate of reaction increased with treatment temperature; crystallinity and crystal size decreased proportionally to pyrolysis temperature. The iso-conversional method coupled with the Kissinger and Flynn-Wall-Ozawa methods were used to determine kinetic parameters via differential scanning calorimetry analysis with different heating rates. The active energy of the reaction was 171.1 and 169.1 kJ/mol, calculated with the two methods respectively and implied the sensitivity of the reaction with temperature.

• Korean Journal of Health Education and Promotion
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• v.22 no.1
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• pp.117-134
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• 2005

This study analyzes how health education program affect elderly's health knowledge, behavior and health state. Also purposes of this program are to have healthy lifestyle and change health behavior to improve life. The subject of study was over 60 years old 175 persons, which include 89 persons of experience group and 86 persons from social well-being center in seoul. The data was collected by measurement of knowledge, behavior on health. The pre-research was performed before health education and post-research was performed immediately after the education. Collected data were analyzed by using the SPSS win 11.0. The results of this study are as follows: 1. The health knowledge points of experience group improved than the control group's and there is statistically significant difference. 2. The health behavior points of experience group were higher than the control group's and the difference was statistically significant. 3. The perceived health state of experience group was better than the control group's and the difference was statistically significant. 4. There are correlations among knowledge, behavior and perceived health state: Knowledge and behavior are positively correlated and behavior and perceived health state have a positive correlation.

• Journal of Korean Critical Care Nursing
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• v.4 no.1
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• pp.37-50
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• 2011

Purpose: This study is to evaluate the effect of abdominal breathing on postoperative pain, state anxiety, blood pressure, and heart rate of cardiac surgery patients treated in intensive care unit. Methods: A non-synchronized design of nonequivalent control group pre-post test was used. Participants were divided into an experimental group(n=22) and a control group(n=21). Just usual postoperative treatments were provided to the control group, while abdominal breathing interventions were provided to the experimental group, in addition to usual treatments. The intervention was consisted of 4 stages-introductions, breathing perception, breathing training, and closing-and it lasted twelve minutes in total. Pain, state anxiety, blood pressure and heart rate were the dependent variables of the abdominal breathing. Results: Those who carried out abdominal breathing showed a significant reduction in pain, as well as decrease of systolic blood pressure. However, it turned out to have no effect on state anxiety, diastolic blood pressure and heart rate. Conclusion: Abdominal breathing is simple and harmless and is effective for reducing postoperative pain.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.3
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• pp.67-78
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• 1997

The objective of study was to examine to transient response of hydraulic shock loading in activated sludge process for treatment of municipal sewage. The general experiment approach was to operate the system under steady-state(pre-shock), then to apply step changes during 24hours in fourfold hydraulic shock loading at the same organic loading. Performance was assessed in both the transient state and the new steady-state(post-shock). Three bench scale activated sludge reactors were operated to investigate the effect of fourfold hydraulic shock loading on TSS and COD removal efficiency. In activated sludge reactors operated with 13hours and 7hours of HRT, effluent quality of all reactors was not changed for few effects, and also showed no foaming and no sludge bulking. Those results are the same as sludge withdrawn reactors. The effect of fourfold hydraulic shock loading on the activated sludge reactors operated with 3hours of HRT was most severe. The effluent quality was deteriorated significantly and generate foaming in reactors. Less than 24hours after the fourfold shock loading applied, the activated sludge system seemed to attain a new steady-state condition as show by effluent.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.18 no.1
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• pp.54-62
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• 2011

Purpose: The purpose of this study was to test the effects of aroma inhalation on subjective quality of sleep, state anxiety, and depression of mothers who underwent a Cesarean section delivery. Methods: This study was designed as a nonequivalent control group quasi-experimental study based upon data acquired through a pre-post test. The experimental group (n=33) was given general obstetric nursing care plus dry inhalation method using lavender essential oil, in which each mother put one drop on a tissue and breathe near it for 5 minutes before going to bed. Then they put 1~2 drops on their pillow for 6 nights. The control group (n=34) was only given general obstetric nursing care. Data were collected using a questionnaire for measures of subjective quality of sleep, state anxiety, and depression by self-report. ${\chi}^2$-test, Fisher's exact test, t-test, and ANCOVA with SPSS/Win12.0 were used to analyze the data. Results: There were significant differences in subjective quality of sleep (p<.001), state anxiety (p=.049) and depression (p=.029). Conclusion: The results suggest that aroma inhalation method can be an effective nursing intervention to improve quality of sleep and decrease anxiety and depression in postpartum mothers suffering from stress related to a Cesarean section delivery.

• Journal of Adhesion and Interface
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• v.15 no.1
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• pp.9-13
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• 2014

The purpose of this work is to investigate the specific gravity, thermal, and mechanical property changes of polypropylene (PP)/mica composites before and after solid-state extrusion. On increasing the filler content, the specific gravity of the composites increased. The specific gravity of the oriented specimen containing filler in PP matrix is found to be much smaller than that of pre-specimen due to the formation of more microvoids. The presence of microvoids in the case of oriented composite specimen significantly affected the tensile and flexural properties of the composites. Both flexural strength and modulus of the composites showed maxima when the mica contents was 10 wt%, regardless of the orientation via solid state extrusion.

• International Journal of Computer Science & Network Security
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• v.22 no.7
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• pp.252-258
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• 2022

Ukraine has a significant in quantity and unique in quality parameters, in particular, the level of education, a resource - the labor force, which, along with natural resources, can serve as the basis for economic growth and the achievement of sustainable development goals. The study is aimed at a thorough identification of the main factors influencing the formation and use of the labor force in Ukraine, including by comparing with the indicators of the EU countries, before the start of the active phase of military aggression by the Russian Federation. It was found that until February 24, 2022, there were negative trends in the change in the quantitative and qualitative indicators of the labor force due to the demographic crisis, the transformation of the national economy and shortcomings in state regulation of labor market development processes. The military actions not only exacerbated pre-existing problems, but also led to the emergence of new ones. A significant number of refugees and internally displaced persons, with the termination of the activities of half of the economic entities, provoked a sharp increase in real unemployment and a decrease in wages. The specific problem of the labor market of Ukraine - the "labor crisis", which has and will have a significant impact on the labor force, is carefully considered.