• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.769-772
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• 2009

Diaphragm compressors are used for a hydrogen compression because it can achieve high gas pressure with high purity. But diaphragm's lifetime may depend on the shape of the cavity and deflection from fluctuation the pressure change, which is necessary to monitored. In this study, the gas and hydraulic oil pressure in the cavity were measured as piston speed varies for diaphragm compressor. The results show pressure change quantities were reduced and maximum pressure points are delayed as the piston moves faster. And the hydraulic pressure were elevated as gas pressure elevated. And the compression period was more faster than expansion period.

• Ocean Systems Engineering
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• v.12 no.4
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• pp.385-402
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• 2022

This paper deals with the study of hydrodynamic pressure in reservoir adjacent to the concrete gravity dam subjected to dynamic excitation. Widely famous finite element method is used to discretize the reservoir domain for modelling purpose. Pressure is considered as nodal variable following Eulerian approach. A suitable nonreflecting boundary condition is applied at truncated face of reservoir to make the infinite reservoir to finite one for saving the computational cost. Thorough studies have been done on generation of hydrodynamic pressure in reservoir with variation of different geometrical properties. Velocity profile and hydrodynamic pressure are observed due to harmonic excitation for variation of inclination angle of dam reservoir interface. Effect of bottom slope angle and inclined length of reservoir bottom on hydrodynamic pressure coefficient of reservoir are also observed. There is significant increase in hydrodynamic pressure and distinct changes in velocity profile of reservoir are noticeable for change in inclination angle of dam reservoir interface. Change of bottom slope and inclined length of reservoir bottom are also governing factor for variation of hydrodynamic pressure in reservoir subjected to dynamic excitation.

• Korean Journal of Hydrosciences
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• v.6
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• pp.99-105
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• 1995

External forecs acting on a pipe bend change when a transient pressure wave propagates through the bend. Analytical expressions are derived to compute the changes of these forces which depend mainly on static pressure rather than fluid momentum. This analysis reveals that the change of the vertical component of the force acting on a pipe bend with an angle larger than 90 may reverse in direction during the passage of a pressure wave through the bend.

• Journal of Physiology & Pathology in Korean Medicine
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• v.16 no.1
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• pp.154-159
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• 2002

There are several types of salts that can be classified into raw salt(Chunil salt), purified salts(NaCl reagent grade) and processed salts(Bamboo salt, Purple bamboo salt using in this study) in Korea. Salts has been utilized for the food as well as for the drug in the Oriental Medicine. Purple bamboo salt(PB-salt) was made by heating up to 1300℃ nine times after putting the raw salts in the bamboo. Since salt is generally known to cause the blood pressure to elevate, this study was conducted to investigate the effect of PB-salt on an adverse reaction of the blood pressure elevation. The experiment was performed with the 2 protocols ; 1. Effect of NaCl and PB-salt administration i.v. with the different the concentration(250, 500, 750, 1000mg/kg) on a mean artery blood pressure(MAP) change. 2. Effect of 500mg/kg NaCl and PB-salt administration p.o. for 6 days on the systolic blood pressure change. The results were as follows; The results were as follows; In a short minute change of blood pressure by direct method, PB-salt adminstration did not induced the hypertension unlike NaCl adminstration. In a date change of blood pressure by indirect method, systolic blood pressure was increased about 12-18% in the NaCl administration group, whereas within 6% in the PB-salt administration group from 2 days to 5 days. These results suggest that PB-salt might have some unidentified ingredient to be changed in the course of processing, making it superior to other salts.

• Journal of Korean Physical Therapy Science
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• v.18 no.4
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• pp.59-64
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• 2011

Purpose : The purpose of this study was to evaluate the effects of the stretching of the calf muscles on foot pressure and contact area in young adult. Participants stood on a wedge board that was sloped between 15~25 degree for 15min. After stretching participants stood quietly on force plate, result was recorded. Participants stood on a force plate for 1 min in eye closed condition, and them the foot pressure and area was recorded. The following variables were calculated off-line: anterior and posterior foot pressure and contact area, medial and lateral foot pressure and contact area. Results showed that anterior pressure change due to stretch, but mediolateral was not significant. This result suggested that stretching of the calf muscle has the effect of increasing anterior pressure by flexibility change on calf muscle, so this effects might be effective intervention for reduce of serious problem to neurologic patients in therapy session.

• Geomechanics and Engineering
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• v.23 no.3
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• pp.207-215
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• 2020

This paper presents a kinematic limit analysis for passive earth pressure of rigid retaining structures considering the unsaturation of the backfill. Particular emphasis in the current work is focused on the effects of the spatial change in the degree of saturation on the passive earth pressure under different steady-infiltration/evaporation conditions. The incorporation of change of effective unit weight with degree of saturation is the main contribution of this study. The problem is formulated based on the log-spiral failure model rather than the linear wedge failure model, in which both the spatial variations of suction and soil effective unit weight are taken into account. Parametric studies, which cover a wide range of flow conditions, soil types and properties, wall batter, back slope angle as well as the interface friction angle, are performed to investigate the effects of these factors on the passive pressure and the corresponding shape of potential failure surfaces in the backfill. The results reveal that the flow conditions have significant effects on the suction and unit weight of the clayey backfill, and hence greatly impact the passive earth pressure of retaining structures. It is expected that present study could provide an insight into evaluation of the passive earth pressure of retaining structures with unsaturated backfills.

• Journal of computational fluids engineering
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• v.20 no.3
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• pp.62-69
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• 2015

Pressure change inside cabin as well as in tunnel has been calculated to assess the passenger pressure comfort of high-speed train. $C-STA^{TM}$, a CFD program based on axi-symmetric Navier-Stokes equation and Roe's FDS has been used to simulate the pressure change in tunnel during a high-speed train passing through it. To present the relative motion between the train and the tunnel, a modified patched grid scheme based on the structured grid system has been employed. The simulation program has been validated by comparing the simulation results with field measurements. Extensive parametric study has been conducted for various train speed, tunnel cross-sectional area and tunnel length to the pressure change in cabin. KTX-Sancheon(KTX2) high-speed train has been chosen for simulation and the train speed have been varied from 200 km/h to 375 km/h. The tunnel length has been varied from 300 m to 7.5 km and tunnel area from $50m^2$ to $120m^2$. Total 504 simulations have been conducted varying the parameters. Based on the database produced from the parametric simulations, minimum tunnel cross-sectional area has been surveyed for various train speeds based on Korean regulation on pressure change in cabin.

• Journal of the Korean Home Economics Association
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• v.29 no.1
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• pp.27-35
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• 1991

This study was carried out to investigate the influence of the various physiological function caused by brassiere wearing. The four experimental methods used in this study are as follows. For example, the Roentgen photographing, Body measurement by Sliding Gauge, the measurement of the Electrocardiogram and Blood Pressure. The results of the Electrocardiogram and Blood Pressure. The results of the investigation were as follows: 1. In experimental change by Sliding Gauge and Body measurement, The bust point was rised in order AB1>B2. The width of right and left bust point was decreased in order of A>B1>B2. According to, The supplementary effect of brassiere wearing was excellent in B2. 2. In the change of various organs by Roentgen photographing, The width of the chest and size of the heart were decreased in regular order of A>B1>B2. The diaphragm and the others were not showed change. 3. In the experimental result by measurement of the electrocardiogram, The interval of heart palpitation was decreased in order A>B1>B2 and the pulse frequency was similar. 4. In the experimental result by the blood pressure measurement, A had the highest blood pressure and B2 had the lowest pressure in all variables.

• The Journal of Korean Physical Therapy
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• v.14 no.3
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• pp.174-202
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• 2002

Twenty five patients, 14 males and 11 females with an average age of 75years with chronic Low Back Pain were tested before, during, and after 10minutes transcutaneous electrical nerve stimulation. It is important to consider the effect of TENS on the autonomic function because the pain pathway and the ANS pathway are somehow correlated to each other. There is still controversy among researchers who have reported the effect of TENS on autonomic function. So the purpose of this study is to measure the effect of TENS on the ANS and to see the relation of the pain control mechanism and the change in the ANS. The results were as follows : 1) Systolic blood pressure between before and during the experiment was apt to be a little increased, but statistically there was no significant change(P>.05). 2) Systolic blood pressure between during and after 10 minutes the experiment was apt to be a little decreased, but statistically there was no significant change(P>.05). 3) Systolic blood pressure between before and after 10 minutes experiment was apt to be a little decreased, but statistically there was no significant change(P>.05). 4) Diastolic blood pressure between before and during experiment was apt to be a little increased, but statistically there was no significant change(P>.05). 5) Diastolic blood pressure between during and after 10 minutes experiment was significantly decreased(P<.05). 6) Diastolic blood pressure between before and after 10 minutes the experiment was apt to be a little decreased, but statistically there was no significant change(P>.05). 7) Heart rate between before and during the experiment was apt to be a little decreased, but statistically there was no significant change(P>.05). 8) Heart rate between during and after 10 minutes the experiment was significantly decreased(P<.05). 9) Heart rate between before and after 10 minutes the experiment was significantly decreased(P<.05). 10) Skin temperature between before and during the experiment was significantly increased(P<.05). 11) Skin temperature between during and after 10 minutes the experiment was apt to be a little increased, but statistically there was no significant change(P>.05). 12) Skin temperature between before and after 10 minutes the experiment was significantly increased(P>.05). 13) Respiratory rate between before and during the experiment was apt to be a little increased, but statistically there was no significant change(Pgt;.05). 14) Respiratory rate between during and after 10 minutes the experiment was apt to be a little decreased, but statistically there was no significant change(Pgt;.05). 15) Respiratory rate between before and after 10 minutes the experiment was apt to be a little decreased, but statistically there was no significant change(P>.05).

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.2
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• pp.50-59
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• 1997

When a front head of train enters a tunnel at a high speed, compression wave is generated at tunnel entrance due to the confinement effect and propagated along the tunnel with sound of speed. The propagated compression wave is reflected at tunnel exit due to abrupt pressure change at passage. The reflected wave is expansion pressure wave. And when the rear head of train goes through the tunnel entrance, another expansion pressure wave is generated and propagated along the tunnel. The pressure drop occurs seriously around train when the two expansion pressure waves come cross on train in the tunnel. In order to reduce the pressure drop, the compression wave front must be controlled because the intensity and magnitude of pressure drop is nearly proportional to that of compression wave at tunnel entrance. This study relates to reduction of the pressure wave gradient with respect to tunnel entrance shape change with various kind of angle and rounding. The results show characteristics of wave propagation in tunnel, usefulness of characteristic curve to estimate proper time domain size in numerical study and measuring time in actual experiment. Also rounding is contributed to improve pressure wave front even if its radius is very small at tunnel entrance. In order to improve of pressure wave front at tunnel entrance, proper angle is prefered to rounding with big radius and an angle of around 14$^{\circ}$ is recommended according to this simulations, And it is expected to reduce additional pressure drop in tunnel when the location and the size of the internal space for attendant equipment are considered in advance.