• Earthquakes and Structures
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• v.8 no.2
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• pp.379-399
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• 2015

Existing building structures can easily present material mechanical properties which can largely vary even within a single structure. The current European Technical Code, Eurocode 8, does not provide specific instructions to account for high variability in mechanical properties. As a consequence of the high strength variability, at the occurrence of seismic events, the structure may evidence unexpected phenomena, like torsional effects, with larger experienced deformations and, in turn, with reduced seismic performance. This work is focused on the torsional effects related to the irregular stiffness and strength distribution due to the concrete strength variability. The analysis has been performed on a case-study, i.e., a 3D RC framed 4 storey building. A Normal distribution, compatible to a large available database, has been taken to represent the concrete strength domain. Different plan layouts, representative of realistic stiffness distributions, have been considered, and a statistical analysis has been performed on the induced torsional effects. The obtained results have been compared to the standard analysis as provided by Eurocode 8 for existing buildings, showing that the Eurocode 8 provisions, despite not allowing explicitly for material strength variability, are conservative as regards the estimation of structural demand.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.10
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• pp.1119-1124
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• 2009

This paper deals with the variability analysis of short term creep rupture test data based on the previous creep rupture tests and the possibility of the creep life prediction. From creep tests performed by constant uniaxial stresses at 600, 650 and $700^{\circ}C$ elevated temperature, in order to investigate the variability of short-term creep rupture data, the creep curves were analyzed for normalized creep strain divided by initial strain. There are some variability in the creep rupture data. And, the difference between general creep curves and normalized creep curves were obtained. The effects of the creep rupture time (RT) and steady state creep rate (SSCR) on the Weibull distribution parameters were investigated. There were good relation between normal Weibull parameters and normalized Weibull parameters. Finally, the predicted creep life were compared with the Monkman-Grant model.

• Journal of Korea Water Resources Association
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• v.36 no.1
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• pp.33-44
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• 2003

Flow duration curves provide a compact summary of streamflow variability. In this study, characteristics of the dimensionless flow duration curve in natural rivers with the unregulated discharge were investigated. An analysis of flow duration characteristics was conducted with discharge data at stage-gauging stations of IHP representative basins and of the major rivers in Korea. Discharge characteristics are dependent on area of watershed. However, flow duration coefficients except drought duration coefficient are independent on that. Abundant flow duration coefficient was constant value. The coefficient of flow duration variability defined in this study as the ratio of the normal stream flow over the drought one is decreased with increasing of the watershed area, which implies that the watershed area affects the drought flow duration variability more than the low flow one. And the coefficient of flow duration variability is increased with the river gradient.

• Earthquakes and Structures
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• v.9 no.2
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• pp.321-337
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• 2015

Existing building structures can easily present material mechanical properties which can largely vary even within a single structure. The current European Technical Code, Eurocode 8, does not provide specific instructions to account for high variability in mechanical properties. As a consequence of the high strength variability, at the occurrence of seismic events, the structure may evidence unexpected phenomena, like torsional effects, with larger experienced deformations and, in turn, with reduced seismic performance. This work is focused on the reduction in seismic performance due to the concrete strength variability. The analysis has been performed on a case-study, i.e., a 3D RC framed 4 storey building. A Normal distribution, compatible to a large available database, has been taken to represent the concrete strength domain. Different plan layouts, representative of realistic strength distributions, have been considered, and a statistical analysis has been performed on the induced reduction in seismic performance. The obtained results have been compared to the standard analysis as provided by Eurocode 8 for existing buildings. The comparison has shown that the Eurocode 8 provisions are not conservative for existing buildings having a large variability in concrete strength.

• Journal of Integrative Natural Science
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• v.14 no.3
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• pp.95-98
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• 2021

By far, studies on the effect of oral administration of peppermint essential oil on blood pressure are not consistent, increasing or decreasing. And the effect of inhalation of peppermint essential oil on blood pressure was not reported. This study was designed to clarify the effect of peppermint essential oil inhalation on the blood pressure and autonomic nervous system. Blood pressure and heart rate variability (HRV) as an indicator of autonomic nervous system activity were measured. The systolic and diastolic blood pressure was not changed significantly by inhalation of peppermint essential oil. Standard deviation of normal to normal (SDNN), a parameter of total activity of autonomic nervous system also was not changed significantly. High frequency (HF) power level, an indicator of parasympathetic nervous system activity was not changed by peppermint. These results indicate that action mechanism of peppermint essential oil on blood pressure is different by the method of administration, oral or inhalation.

• Journal of the Korean Society of Physical Medicine
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• v.9 no.1
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• pp.63-68
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• 2014

PURPOSE: The purpose of this study was to examine the position changes with tilt table on autonomic nervous system using heart rate variability analysis. METHODS: Fourty healthy adult males volunteered in this study. The low frequency, high frequency and low frequency/high frequency ratio and mean heart rate, standard deviation of all normal R-R intervals, root mean square of successive differences, heart rate variability index were measured at the tilt table angle of $0^{\circ}$, $45^{\circ}$ and $90^{\circ}$ with pulsoximeter. Data were analyzed one-way ANOVA and LSD post hoc test. RESULTS: The mean heart rate, low frequency and low frequency/high frequency ratio increased significantly at higher angle of tilt table(p<.05). The root mean square of successive differences, heart rate variability index decreased significantly at lower angle of tilt table(p<.05). The standard deviation of all normal R-R intervals, high frequency decreased at higher angle of tilt table did not show significant difference. CONCLUSION: The symphathetic activity increased significantly at higher angle of tilt table. The parasymphathetic activity decreased at higher angle of tilt table, but the difference were not significant. The autonomic adaptation, balance and heart rate variability decreased significantly at higher angle of tilt table. Based on these results, in the treatment of patients with a change in posture precedence should be carefully treated. Further studies are necessary to determine the most safety and effective methods.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.15 no.1
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• pp.21-32
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• 2003

In this study, the reliability design method developed by Hanzawa et al. in 1996 for calculation of the expected damage to armor blocks of a horizontally composite breakwater is extended to take into account the variability in wave direction such as directional spreading of waves, obliquity of the design principal wave direction from the shore-normal direction, and its variation about the design value. To calculate the transformation of random directional waves. the model developed by Kweon et al. in 1997 is used instead of Goda's model, which was developed in 1975 for unidirectional random waves normally incident to a straight coast with parallel depth contours and has been used by Hanzawa et al. It was found that the variability in wave direction had great influence on the computed expected damage to armor blocks. The previous design, which disregarded wave directionality, could either overestimate or underestimate the expected damage by a factor of two depending on water depth and seabed slope, if the assumption of the present study that the stability formula for breakwater armor blocks proposed for normal incidence can be used for obliquely incident waves is valid.

• The Journal of Korean Medicine
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• v.35 no.4
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• pp.24-35
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• 2014

Objectives: Although the autonomic nervous system (ANS) is thought to play an important role in treatment of obesity, no study has been conducted to investigate acupuncture's effects on this aspect of the ANS. This study aimed to describe the effects of acupuncture in the ANS by means of heart rate variability (HRV) analysis. Methods: A total of 46 obese women aged from 21 to 54 with body mass index ranging from 25.1 to $39.3kg/m^2$ were recruited and randomized into both the real acupuncture group (n=23) and sham acupuncture group (n=23). A total of 3 instances of HRV analysis were conducted before, during, and after treatment. Statistically significant differences between time and groups were analyzed using repeated measure analysis of variance. Results: All parameters of time domain analysis and frequency domain analysis except for the square root of the mean squared differences of successive normal sinus intervals (RMSSD) and very low frequency (VLF) showed significant differences between times. The mean of all R-R intervals (mean RR) showed significant level of interaction between time and group. Between groups, time domain analysis of standard deviation of the normal-to-normal intervals (SDNN), RMSSD and frequency domain analysis of total power (TP) and high frequency (HF) showed significant differences. Conclusions: The real acupuncture group showed deactivation of parasympathetic function and relative increase of sympathetic activity in obese subjects. Further studies are necessary to uncover the mechanisms of acupuncture in obesity treatment.

• Korean Journal of Biological Psychiatry
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• v.15 no.3
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• pp.186-193
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• 2008

Objectives : The authors tried to investigate the characteristics of Heart Rate Variability(HRV) among the subjects with metabolic syndrome for testing the possibility of clinical application of HRV in evaluating metabolic syndrome. Methods : We examined the difference of the means of HRV between 122 subjects of metabolic syndrome and 1057 healthy controls using T-test, and the change of means in HRV according to increasing risk factors of metabolic syndrome. Using multiple regression analysis, we examined the association of HRV with the risk factors of metabolic syndrome. Results : The HRV indices including SDNN(Standard Deviation of all normal NN intervals), RMSSD(the square Root of the Mean Squared Differences of successive all normal NN interval), TP(Total Power), LF(Low Freuency), and HF(High Frequency) were significantly lower in the metabolic syndrome group than in the normal control group, and the means of all HRV indices except LF/HF were decreased consistently according to increasing risk factors of metabolic syndrome. The fasting glucose, triglyceride, and waist circumference were dependent factors that contributed significantly to the change of HRV. Conclusion : These findings suggest metabolic syndrome adversely affects cardiac autonomic system and HRV could be a useful method for evaluating metabolic syndrome.

• The Journal of Korean Medicine
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• v.28 no.2 s.70
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• pp.114-125
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• 2007

Objectives : Uterine myoma is the most common pelvic benign tumor and may cause abnormal menstrual pattern. The growth of uterine myoma depends on hormones. The 7-zone-diagnostic system (CP-6000A) is a measuring system using skin resistance variability (SRV). The machine shows organic energy and was reported by the gynecologic department to detect functional abnormality of hypothalamus-hypophysis-ovarian axis (H-P-O). Our study was to investigate the SRV of women with uterine myoma by the 7-zone diagnostic system. Methods: Two groups were selected from those who took the CP-6000A test in the College of Korean Medicine Hospital of Sangji University from March 2003 to September 2006. They were divided into normal control (n=40) and uterine myoma groups (n=40). Electrodermal activity of the two groups was compared. Results : The mean value of electrodermal activity of the uterine myoma group was lower than that of thenormal group in all areas on first and second measurement. Especially, the mean value of the patient group was significantly lower than that of the normal group and fell below normal range in the 1, 2, and 3 areas on first and second measurement. Conclusions : The results suggest that women with uterine myoma may have organic energy deficiency and functional abnormality of the H-P-O axis. Further studies to determine the feasibility of this 7 -zone diagnostic system as a reliable diagnostic tool are needed.