• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.6
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• pp.429-445
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• 2008

Two-phase compressible flow fields of air-water are investigated numerically in the fixed Eulerian grid framework. The phase interface is captured via volume fractions of each phase. A way to model two phase compressible flows as a single phase one is found based on an equivalent equation of states of Tait's type for a multiphase cell. The equivalent single phase field is discretized using the Roe‘s approximate Riemann solver. Two approaches are tried to suppress the pressure oscillation phenomena at the phase interface, a passive advection of volume fraction and a direct pressure relaxation with the compressible form of volume fraction equation. The direct pressure equalizing method suppresses pressure oscillation successfully and generates sharp discontinuities, transmitting and reflecting acoustic waves naturally at the phase interface. In discretizing the compressible form of volume fraction equation, phase interfaces are geometrically reconstructed to minimize the numerical diffusion of volume fraction and relevant variables. The motion of a projectile in a water-filled tube which is fired by the release of highly pressurized air is simulated presuming the flow field as a two dimensional one, and several design factors affecting the projectile movement are investigated.

• Journal of Korean Academy of Nursing
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• v.30 no.4
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• pp.825-835
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• 2000

The agitation of dementia patient is a factor which aggravates the care-givers' burdon, and it is needed to develop intervention methods. Hall and Buckwalter hypothesized that an increase in agitation behavior occur when persons experience high levels of stress. This study was conducted to explore the efficacy of hand massage in producing relaxation and decreasing agitation behaviors in persons with dementia. Hand massage was administered once a day in afternoon for 8days to 24 patients and 4days to 23 patients. There was no difference in result between the two groups. Significant differences were found in systolic blood pressure, pulse rate, emotional state from pre to post -intervention with the use of hand massage. The change of systolic blood pressure was 26% explained by ADL, MMSE-K and institutionalized period. The most significant variable was institutionalized period. The change of diastolic blood pressure was 11% explained by ADL, and it was significant. But no decrease in agitation behavior was observed and no increase in functional capacity.

• Korea-Australia Rheology Journal
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• v.21 no.4
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• pp.203-211
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• 2009

In flows with deformation rates larger than the inverse Rouse time of the polymer chain, chains are stretched and their confining tubes become increasingly anisotropic. The pressures exerted by a polymer chain on the walls of an anisotropic confinement are anisotropic and limit chain stretch. In the Molecular Stress Function (MSF) model, chain stretch is balanced by an interchain pressure term, which is inverse proportional to the $3^{rd}$ power of the tube diameter and is characterized by a tube diameter relaxation time. We show that the tube diameter relaxation time is equal to 3 times the Rouse time in the limit of small chain stretch. At larger deformations, we argue that chain stretch is balanced by two restoring tensions with weights of 1/3 in the longitudinal direction of the tube (due to a linear spring force) and 2/3 in the lateral direction (due to the nonlinear interchain pressure), both of which are characterized by the Rouse time. This approach is shown to be in quantitative agreement with transient and steady-state elongational viscosity data of two monodisperse polystyrene melts without using any nonlinear parameter, i.e. solely based on the linear-viscoelastic characterization of the melts. The same approach is extended to model experimental data of four styrene-butadiene random copolymer melts in shear flow. Thus for monodisperse linear polymer melts, for the first time a constitutive equation is presented which allows quantitative modeling of nonlinear extension and shear rheology on the basis of linear-viscoelastic data alone.

• PNF and Movement
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• v.19 no.3
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• pp.413-422
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• 2021

Purpose: This study was conducted to investigate changes in the cervical and lumbar flexion-relaxation ratio, range of motion, pressure pain threshold, and perceived comfort following the wearing of a trunk brace during smartphone watching. Methods: To calculate the number of subjects for this study, an analysis with G^*Power was performed at a statistical power of 0.8, an effect size of 0.5, and a significance level of 0.05, based on the results of a preliminary experiment on five subjects. In total, 27 adult men and women were recruited who had been informed of the study's purpose and process and had agreed to participate. All subjects watched content on a smartphone for 20 minutes in the same posture and conditions while wearing and not wearing a trunk brace, and then their cervical and lumbar flexion-relaxation ratio, range of motion, pressure pain threshold, and perceived comfort were measured. Results: Compared to the non-wearing of a trunk brace, the wearing of a trunk brace resulted in a statistically significant smaller decline in cervical extension and right-side cervical rotation (p<0.05). When the subjects wore a trunk brace, their right- and left-side cervical and right-side lumbar pressure pain statistically significantly improved when compared to not wearing a trunk brace (p<0.05). They also perceived a significantly lowered level of comfort 20 minutes after wearing a trunk brace compared to immediately after wearing it (p<0.05). Conclusion: The trunk brace was effective in reducing declines in right-side cervical rotation and the occurrence of left- and right-side cervical and right-side lumbar pressure pain. The findings indicate the need to improve the perceived comfort of trunk braces.

• Proceedings of the Korean Society of Food Hygiene and Safety Conference
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• 2002.05a
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• pp.137-137
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• 2002

Several epidemiologidal studies suggested that arsenic exposure was strongly correlated with the development of cardiovascular disease such as hypertension. In order to examine whether arsenic affects vasomotor tone in blood vessels, we investigated the effect of arsenic on agonist-induced vasorelaxation using the isolated rat aortic ring in in vitro organ bath system. Treatment with arsenite inhibited acetylcholine-induced relaxation of aortic rings in a concentration- dependent manner. The inhibitory effects by arsenic were also observed in the relaxation induced by sodium nitroprusside, a NO-donor. Consistent with these findings, the cGMP levels stimulated by acetylcholine in blood vessels were reduced significantly by arsenite treatment. In addition, higher concentration of arsenite decreased the relaxation by 8-Br-cGMP, a cGMP analog, in aortic rings without endothelium. These in vitro results indicated that arsenite that arsenite was capable of suppressing acetylcholine-induced relaxation in blood vessels by inhibiting production of nitric oxide in endothelial cells and by impairing the relaxation machinary in smooth muscle cells. In vivo studies revealed that the reduction of blood pressure by acetylcholine infusion was signigicantly suppressed after arsenite was administered intravenously to rate. These data suggest that vasomotor tone impaired by arsenite exposure may be one of the contrbuting factors in development of cardiovascular disease.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.216-217
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• 2008

In recent years, scientific community has found renewed interest in hypersonic flight research. These hypersonic vehicles undergo severe aero-thermal environment during their flight regimes. During reentry and hypersonic flight of these vehicles through atmosphere real gas effects come into play. The analysis of such hypersonic flows is critical for proper aero-thermal design of these vehicles. The numerical simulation of hypersonic real gas flows is a very challenging task. The present work emphasizes numerical simulation of hypersonic flows with thermal non-equilibrium. Hyperbolic system of equations with stiff relaxation method are identified in recent literature as a novel method of predicting long time behaviour of systems such as gas at high temperature. In present work, Energy Relaxation Method (ERM) has been considered to simulate the real gas flows. Navier-Stokes equations A numerical scheme Advection Upstream Splitting Method (AUSM) has been selected. Navier-Stokes solver along with relaxation method has been used for the simulation of real flow over a circular cylinder. Pressure distribution and heat flux over the surface of cylinder has been compared with experiment results of Hannemann. Present heat flux results over the cylinder compared well with experiment. Thus, real gas effects in hypersonic flows can be modeled through energy relaxation method.

• Journal of East-West Nursing Research
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• v.15 no.1
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• pp.54-62
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• 2009

Purpose: The purpose of this study was to examine the effects of relaxation therapy to reduce anxiety level among spinal anesthesia surgery patients. Methods: The study employed a quasi-experimental pre-and-posttest design with nonequivalent control group. The experimental group was provided with the 15-min muscle relaxation therapy on the day before the surgery and an hour before the spinal anesthesia. Data were collected from 44 patients (22 in experimental and 22 in control group) who were planned to have spinal anesthesia surgery from an orthopedic surgery department at a general hospital in Seoul from January 13 to March 21, 2006. Results: The experimental group reported lower level of state anxiety after the surgery (23.18 vs. 33.64) than did control group but was not statistically significant. There were no significant differences in blood pressure or pulse rate between experimental and control groups after surgery. Conclusions: The further research should be conducted to polish the muscle relaxation therapy for various types of patients and to create more comfortable environment setting for application of the therapy. The muscle relaxation therapy may be a convenient and useful nursing intervention to reduce anxiety among spinal anesthesia surgery patients if more studies prove its effectiveness.

• Transactions of Materials Processing
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• v.16 no.4 s.94
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• pp.260-265
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• 2007

Rubber compounds have high viscoelastic property. One of the viscoelastic behaviors during profile extrusion is the swelling of extrudate. In this study, die swells of rubber compounds at the capillary die have been investigated through experiment and computer simulation. Experiments and simulations have been performed using fluidity tester and commercial CFD code, Polyflow respectively. Die swells of rubber compounds in a capillary die were predicted using non-linear differential viscoelastic model, Phan-Thien-Tanner(PTT) model for various relaxation times and relaxation modes. The results of simulation were compared with the experiments. Pressure and velocity distribution, and circulation flows at the comer of capillary die have been investigated through computer simulation. It is concluded that the PTT model successfully represented the amount of the die swell of rubber compounds for various relaxation times at different modes.

• The Journal of Pediatrics of Korean Medicine
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• v.12 no.1
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• pp.163-181
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• 1998

The purpose of this study was to analyze the Rhizoma on the blood pressure, heart rate and to define the mechanism of Notopterygii Rhizoma-induced relaxation in rabbit common carotid arterial contracted by agonists. Method : In order to explore the effect of Notopterygii Rhizoma on the blood pressure and heart rate, Notopterygii Rhizoma extract was injected in vein of rabbit ear. In order to investigate the effect of Notopterygii Rhizoma on norepinephrine(NE)-induced contracted rabbit carotid arterial strips, transverse strips with intact or damaged endothelium were used for the experiment using organ bath. To analyze the mechanism of Notopterygii Rhizoma-induced relaxation, Notopterygii Rhizoma extract infused into NE-induced contracted strips induced by agonists after treatment of methylene blue, propranolol, ouabain and it infused into serotonin, potassium chloride-induced contracted strips. Result : The blood pressure was significantly decreased by Notopterygii Rhizoma, but heart rate was insignificantly. In addition, Notopterygii Rhizoma significantly relaxed the norepinephrine, serotonin, potassium-induced contracted strips with intact endothelium or damaged endothelium. The relaxing effect of Notopterygii Rhizoma In NE-induced contracted strips with damaged endothelium by pretreatment of methylene blue, propranolol was not changed, but Ouabain was significantly decreased. Conclusion : These results were shown that Notopterygii Rhizoma affected the NE -induced contracted smooth muscle without the participation of endothelium, and demonstrated that the mechanism of NotoDtervgii Rhizoma-induced relaxation was the obstruction of receptor-operated Ca2+ channel.

• The Korean Journal of Pharmacology
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• v.13 no.1 s.21
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• pp.13-21
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• 1977

The author confirmed the development of the smooth muscle in the oviduct proprius and anterior mesosalpinx in the leghorn, and observed that there was a variation between the action of norepinephrine on albumin-secreting portion of productive oviduct and that of non-productive one, and that $PGE_1$ might play a significant role on the activation of adrenergic ${\alpha}$-receptor in the non-productive oviduct. 1. There were many bundles of smooth muscles with irregular directions, which were identified in the both oviduct proprius and anterior mesosalpinx by Mallory aniline-blue orange G stain. 2. In vitro experiments, the anterior mesosalpinx was always relaxed by norepinephrine. While the albumin-secreting portion of non-productive period of oviduct was relaxed, but that of the productive one contracted by norepinephrine. Both the anterior mesosalpinx and oviduct proprius of chick responsed with relaxation to norepinephrine as shown in the non-productive hen. In vivo experiments, norepinephrine injected through the jugular vein increased the intraoviductal pressure in the productive oviduct, but decreased that in the non-productive one. 3. By treatment with $PGE_1$, in vitro, the relaxation induced not only by norepinephrine, but by periarterial electrical stimulation was converted into contraction, and in the presence of phentolamine, this conversion by $PGE_1$ was not shown. 4. The intra-oviductal pressure of the productive hen treated with indomethacin for 4 days was decreased by norepinephrine, but the increase in pressure by $PGE_1$ or $PGE_{2{\alpha}}$ was supersensitized when these drugs were administered through jugular vein. However, in vivo, the relaxation by norepinephrine was not converted into the stimulation after $PGE_1$ treatment. It might be summarized that the regulation of intra-oviductal pressure was dependent on the summation of the movement of both oviduct and mesosalpinx and intramurally produced prostaglandins contributes to the inherent tone of the prcductive oviduct by activating adrenergic ${\alpha}$-receptor.