• Proceedings of the Korean Society of Rheology Conference
• /
• 2003.05a
• /
• pp.111-114
• /
• 2003

No Abstract, See Full Text

• Proceedings of the Korean Society of Rheology Conference
• /
• 2002.11a
• /
• pp.47-50
• /
• 2002

No Abstract, See Full Text

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2007.05a
• /
• pp.254-259
• /
• 2007

During the ground fault conditions, the flow of current to earth will produce potential gradients within and arround a substation. The common physiological effects of electric current on the body, stated in order of increasing current magnitude, are threshold perception, muscular contraction, unconsciousness, fabrillation of the heart. In this study, determined the tolerable voltage about earth-layered structure in the grounding system.

• Journal of the Korean Mathematical Society
• /
• v.42 no.4
• /
• pp.827-845
• /
• 2005

In this paper, we present a general method for the stability analysis of some bursting models. Our method is geometric in the sense that we consider a flow-defined return map defined on a section and determine when the map is a contraction. We find that there are three different stability types in the codimension-1 planar bursters.

• The Bulletin of The Korean Astronomical Society
• /
• v.40 no.1
• /
• pp.58.2-58.2
• /
• 2015

We investigate the decaying incompressible MHD turbulence by including the effect of the expansion and contraction of background medium. In such an environment, incompressible MHD turbulence has two kinds of time scale. One is the eddy turn-over time (teddy), the other is the expansion/contraction time (texp-cntr). The turbulence is expected to behave differently according to the relationship between the two time scales. For instance, for teddy < texp-cntr, the turbulence would be decay more or less as in a static medium. On the other hand, for teddy > texp-cntr, the effects of expansion and contraction would be dominant. We examine the properties of turbulence in these two regime cases. Based on it, we derive a scaling for the time evolution of flow velocity and magnetic field. (i) In the decay effect dominant case, the velocity and magnetic field scale as $\sqrt{{\rho}v}{\sim}a^{-3}$, $b{\sim}a^{-2.5}$(expanding media) and $\sqrt{{\rho}v}{\sim}a^{-2}$, $b{\sim}a^{-1.5}$(contracting media). The total energy and residual spectra follow the $E^T_k{\sim}k^{-5/3}$, $E^R_k{\sim}k^{-7.3}$ in the inertial range. (ii) In the expanding and contracting dominant case, the velocity and magnetic field scale as $\sqrt{{\rho}v}{\sim}a^{-2.5}$, $b{\sim}a^{-2}$ (expanding/contracting media). The Kinetic and magnetic energy spectra follow the $E^K_k{\sim}a^{-5}$, $E^M_k{\sim}a^{-4}$. We have confirmed that scaling of velocity and magnetic filed is almost the same from the analytic estimates and computational models

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.22 no.3
• /
• pp.593-599
• /
• 2008

This research was aimed to examine the effect of Polygoni Multiflori Radix extract on the blood pressure in spontaneous hypertensive rat (SHR) and norepinephrine - induced arterial contraction in rabbit. In order to investigate the effect of Polygoni Multiflori Radix on rabbit's contracted vascular ring detached from common carotid artery, vascular ring with intact or damaged endothelium was used for the experiment using organ bath. To analyze the mechanism of Polygoni Multiflori Radix-induced relaxation, Polygoni Multiflori Radix extract was infused into contracted vascular ring which had been pretreated by $N{\omega}$-nitro-L-arginine(L-NNA), Methylene blue(MB), and $Ca^{2+}$ was infused into contracted vascular ring induced by NE after treatment of Polygoni Multiflori Radix extract in $Ca^{2+}$-free solution. The results were as follows: Systolic blood pressure was significantly attenuated by administration of Polygoni Multiflori Radix. Blood flow and aldosterone were significantly decreased, but velocity and renin were not affected by Polygoni Multiflori Radix. Polygoni Multiflori Radix had an effective relaxation to the contracted vascular ring by NE in 0.03 mg/ml, 0.1 mg/ml and 0.3 mg/ml level. Polygoni Multiflori Radix had an effective relaxation to the intact endothelium vascular ring, but when endothelium was removed, vascular ring did not relax. Polygoni Multiflori Radix-induced relaxation was inhibited by the pretreatment of L-NNA and MB. Pretreatment of Polygoni Multiflori Radix extract inhibit the contraction by influx of extra-$Ca^{2+}$ in contracted vascular ring induced by NE in $Ca^{2+}$-free solution. As mentioned above, we suggest that Polygoni Multiflori Radix relaxes vascular ring through suppress influx of extra-cellular $Ca^{2+}$ by the action of nitric oxide from endothelium.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.19 no.6
• /
• pp.1573-1579
• /
• 2005

This study was undertaken to define the effect of DaeSiHo-Tang extract on the hypertension in spontaneous hypertensive rat and norepinephrine-induced arterial contraction in rabbit. Systolic blood pressure and blood velocity were significantly attenuated by administration of DaeSiHo-Tang extract. but blood flow and renin-angiotensin-aldosterone system unaffected by DaeSiHo-Tang extract. The relaxation effect of DaeSiHo-Tang extract was dependent on the presence of endothelium, showing that DaeSiHo-Tang extract-induced relaxation was not observed in the strips without endothelium. The endothelium-dependent relaxation induced by DaeSiHo-Tang extract was decreased by the pretreatment of $N{\omega}$-nitro-L-arginine or methylene blue, but it was not observed in the strips pretreated with indomethacin or tetraethylammonium chloride. When $Ca^{2+}$ was applied, the strips which were contracted by norepinephrine in a $Ca^{2+}$-free solution, arterial contraction was increased. But pre-treatment of DaeSiHo-Tang extract inhibited contractile response to $Ca^{2+}$. These results indicate that antihypertensive effect of DaeSiHo-Tang extract is due to descend arterial resistance by the arterial relaxation through the formation of nitric oxide in the vascular endothelial cells.

• Journal of the Society of Naval Architects of Korea
• /
• v.51 no.1
• /
• pp.1-7
• /
• 2014

The present study numerically investigated the effect of the advance ratio on the wake characteristics of the marine propeller in the propeller open water test. Therefore, a wide range of the advance ratio(0.2${\kappa}-{\omega}$SST Model are considered. The three-dimensional vortical structures of tip vortices are visualized by the swirl strength, resulting in fast decay of the tip vortices with increasing the advance ratio. Furthermore, to better understanding of the wake evolution, the contraction ratio of the slip stream for different advance ratios is extracted from the velocity fields. Consequently, the slip stream contraction ratio decreases with increasing the advance ratio and successively the difference of the slip stream contraction ratio between J=0.2 and J=0.8 is about 0.1R.

• Journal of Sensor Science and Technology
• /
• v.30 no.2
• /
• pp.109-113
• /
• 2021

In this study, an automated culture media replacement system was developed to analyze changes in the contraction characteristics of cardiomyocytes according to the state of the culture media. For the long-term storage of culture media, a Peltier refrigerator with a temperature of 5 to 8℃ was provided and a pH of 7.4 was maintained. The cell culture media of the cardiomyocytes was continuously replaced using interlocking pumps at a flow rate of 0.83 μl/h. The cardiomyocytes in which the culture media was replaced automatically demonstrated lower heartbeats per minute compared to samples in which there was no replacement. However, these cardiomyocytes moved more uniformly and produced greater displacement in one heartbeat cycle. It was observed that the sarcomere length of the cardiomyocytes increased due to the automated culture media replacement system. These cardiomyocytes were found to demonstrate better maturation compared to the control group. The maturation of cardiomyocytes was verified through staining images. The proposed automated culture media replacement system generates a uniform heart rate and improvements in contraction force. Based on the study, patient-specific drug toxicity assessments can be conducted using differentiated cardiomyocytes in induced pluripotent stem cells.

• Journal of Korean Physical Therapy Science
• /
• v.29 no.2
• /
• pp.57-65
• /
• 2022

Background: This study was to determine whether the diaphragmatic breathing exercise using a DiP Belt(Diaphragmatic Pressure Belt) is effective in increasing the diaphragmatic motion and forced vital capacity. Design: Pretest-Posttest design. Methods: A total of 44 subjects(15 male, 29 female) participated in this study. All subjects were measured the diaphragmatic motion with a sonography and the Forced Vital Capacity(FVC) was measured with a digital spirometer. After 4 weeks, the subjects were intervened the diaphragmatic breathing exercise using a DiP belt and were remeasured for diaphragm motion and FVC. Results: After exercise intervention, quiet breathing significantly increased with the change in diaphragmatic motion and showed a moderate effect size (p<.01, Cohen's d = -0.53). In addition, it was significantly increased in deep breathing and showed a high effect size (p<.001, Cohen's d = -1.32). The mean diaphragmatic contraction pressure increased, but there was no significant difference and the peak diaphragmatic contraction pressure increased significantly (p<.05). Both diaphragmatic contraction pressure showed small effect sizes (respectively Cohen's d = -0.28, -0.33). In spirometry, FVC, Forced Expiratory Volume in 1 second (FEV₁), and FEV₁/FVC% all increased, but there was no significant difference. Only peak expiratory flow increased significantly and showed a small effect size (p<.05, Cohen's d = -0.41). Conclusion: The DiP belt diaphragmatic breathing exercise that the principle of visual feedback can correct diaphragm breathing in a short time, so it is a useful breathing exercise device that can help the diaphragm breathing exercise in the right way in clinical practice.