• Journal of the Korean Wood Science and Technology
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• v.26 no.4
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• pp.1-5
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• 1998

In this study, it was examined the method to estimate equilibrium moisture content(EMC) at high vapor pressures and high temperatures above $100^{\circ}C$. The material used for the experiment was Sugi(Cryptomeria japonica). EMC was investigated at temperatures ranging from $100^{\circ}C$ to $160^{\circ}C$ and under saturated vapor pressures above 1 atm. The correlation between temperatures and vapor pressures have a good agreement with those observed by thermocouple and pressure gauge in the air state of autoclave, respectively. A sensitivity of quartz spring was 65mm/g. Moisture content(MC)s calculated from the quartz spring elongation by vapor sorption showed a good agreement with MCs by oven-dried method. Using this system, it was found that EMC at high vapor pressures and high temperatures above $100^{\circ}C$ were higher than EMC of wood in 1 atm pressure conditions. With this system, therefore, it was concluded that the EMCs of wood and wood-based materials at high temperatures were able to be evaluated.

• Wind and Structures
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• v.32 no.2
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• pp.105-114
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• 2021

This paper describes a wind tunnel test on a 1:25 scale model of TTU building with several adjustable openings in order to comprehensively study the characteristics of fluctuating internal pressures, especially the phenomenon of the increase in fluctuating internal pressures induced by tangential flow over building openings and the mechanism causing that. The effects of several factors, such as wind angle, turbulence intensity, opening location, opening size, opening shape and background porosity on the fluctuating internal pressures at oblique wind angles are also described. It has been found that there is a large increase in the fluctuating internal pressures at certain oblique wind angles (typically around 60° to 80°). These fluctuations are greater than those produced by the flow normal to the opening when the turbulence intensity is low. It is demonstrated that the internal pressure resonances induced by the external pressure fluctuations emanating from flapping shear layers on the sidewall downstream of the windward corner are responsible for the increase in the fluctuating internal pressures. Furthermore, the test results show that apart from the opening shape, all the other factors influence the fluctuating internal pressures and the internal pressure resonances at oblique wind angles to varying degrees.

• Journal of Sensor Science and Technology
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• v.22 no.2
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• pp.136-143
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• 2013

In the study, novel blood pressure estimation method was proposed to improve the accuracy of oscillometric method. The proposed algorithm estimated the blood pressure by comparing and analyzing the point variation aspect of dicrotic notch on pulsating waveform during each cardiac cycle. The waveforms of each cardiac cycle were extracted by maximum points. The extracted pulsating waveforms were applied by re-sampling, end-matching, and normalization. The systolic and diastolic blood pressures were estimated by point variation aspect of dicrotic notch. The blood pressures, which were estimated from proposed algorithm, were compared and analyzed by blood pressures from oscillometric methods and auscultation. The systolic blood pressure from oscillometric methods were +0.88 mmHg more than proposed algorithm, and 1.875 less than the diastolic blood pressures from proposed algorithm. The systolic and diastolic blood pressures from auscultation were 2.89 mmHg and 3.44 mmHg less than the blood pressures from proposed algorithm. As the errors between blood pressures from proposed algorithm, oscillometric method and auscultation were less than 5 mmHg, the proposed algorithm was effective.

• Journal of the Korean Geotechnical Society
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• v.22 no.8
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• pp.33-42
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• 2006

Geosynthetics reinforced soil (GRS) walls with a flexible wall face allow deformation. GRS walls constructed on the weak ground change in both horizontal earth pressures on wall faces and the tensile stress of geosynthetics, affecting the backfill in time until the deformation of the backfill and the foundation is completed. However, there are few studies that were done to measure and analyze the horizontal earth pressures and geosynthetics deformation on GRS walls constructed on the soft ground for a long period of time. Two field GRS walls in this study are constructed on a shallow layer of a weak foundation to measure and analyze geostynthetics deformation, horizontal earth pressures, and pore water pressures for the duration of approximately 16 months. Strain gauges are used to measure geosynthetics deformation; this study specifically suggests a new method of measuring nonwoven geotextile using strain gauges. Most geosynthetics deformation occurred within a month after the construction of GRS walls. The maximum deformation measured for approximately 16 months appeared as follows: nowoven geotextile: 6.05%, woven geotextile: 2.92%, and geogrid: 2.33%. Pore water pressures on the GRS wall can be ignored; however, horizontal earth pressures on the bottom and the upper part of the wall face appear larger than earth pressures at rest.

• Wind and Structures
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• v.30 no.1
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• pp.99-117
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• 2020

This paper focuses on the processes of wind flow in atmospheric boundary layer, to produce realistic full scale pressures for design of low-rise buildings. CFD with LES turbulence closure is implemented on a scale 1:1 prototype building. A proximity study was executed computationally in CFD with LES that suggests new recommendations on the computational domain size, in front of a building model, apart from common RANS-based guidelines (e.g., COST and AIJ). Our findings suggest a location of the test building, different from existing guidelines, and the inflow boundary proximity influences pressure correlation and reproduction of peak loads. The CFD LES results are compared to corresponding pressures from open jet, full scale, wind tunnel, and the ASCE 7-10 standard for roof Component & Cladding design. The CFD LES shows its adequacy to produce peak pressures/loads on buildings, in agreement with field pressures, due to its capabilities of reproducing the spectral contents of the inflow at 1:1 scale.

• Magazine of the Korean Society of Agricultural Engineers
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• v.38 no.5
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• pp.85-94
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• 1996

For the geotechnical analysis in the construction and Deign of the coastal structures, one of the most important factors is the existence of waves. The dynamic behavior and deformation of the seabed subjected to wave load must be considered. It is expected that the soil behavior in the seabed subjected to cyclic wave load is much different from that on the ground subjected to dynamic forces such as earthquake. The purposes of this study are as follows ; Firstly, to provide a testing method to generate wave loads in the laboratory and measuring oscillatory pore water pressures in the unsaturated marine silty sand specimen, Secondly, to analyze the mechanism of wave induced pore water pressures and liquefaction potentials under the conditions in the testing. It is shown that the test set-up manufactured especially for the test is good to generate oscillatory wave pressures to the specimen with sine wave type. From the results of this study, it is understood that the pore water pressure due to induced waves is not accumulated as the wave number increases but is periodically varied with wave passage on still water surface. The magnitude of pore water pressures measured tends to be diminished radically with a certain time lag under the action of both high and low waves as depth increases.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.11
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• pp.1527-1537
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• 1997

Extinction characteristics and acoustic response of hydrogen-air diffusion flames at various pressures are numerically studied by employing counterflow diffusion flame as a model flamelet in turbulent flames in combustion chambers. The numerical results show that extinction strain rate increases linearly with pressure and then decreases, and increases again at high pressures. Thus, flames are classified into three pressure regimes. Such nonmonotonic behavior is caused by the change in chemical kinetic behavior as pressure rises. The investigation of acoustic-pressure response in each regime, for better understanding of combustion instability, shows different characteristics depending on pressure. At low pressures, pressure-rise causes the increase in flame temperature and chain branching/recombination reaction rates, resulting in increased heat release. Therefore, amplification in pressure oscillation is predicted. Similar phenomena are predicted at high pressures. At moderate pressures, weak amplification is predicted since flame temperature and chain branching reaction rate decreases as pressure rises. This acoustic response can be predicted properly only with detailed chemistry or proper reduced chemistry.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.943-945
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• 2003

This study is to evaluate the change of intra-abdominal pressure related with intravesical and intrarectal pressure in patients with spinal cord injury according to daily activities and postural changes which make the abdominal pressure elevated. The intravesical and the intrarectal pressures were obtained during patient's speech, sneeze, cough, valsalva and various postural changes with supine to decubitus, derubitus to supine, supine to sit, and sit to supine according to empty and full bladders, respectively. The order of higher intravesical and intrarectal pressure rise during various maneuvers were valsalva, sneeze, supine to sit and cough, respectively. Higher correlation coefficient between the intrvesical and intrarectal pressures were noted during cough, sneeze, valsalva and supine to sit in empty bladder than full one. These results demonstrated that the intravesical and intrarectal pressures were influenced by daily activities and postural changes of increasing the intra-abdominal pressure. The intrarectal pressures according to daily activities such as cough, sneeze, valsalva and postural change were significantly related with intravesical pressures.

• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.209-219
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• 2006

The supersonic combustion experiments are carried out using T3 free-piston shock tunnel. Different shock tube fill pressures have various inflow conditions. $15^{\circ}$ inclined hydrogen fuel injection is located before the cavity. Oblique shock is generated at the trailing edge of the cavity and reflects off the top and bottom wall. For non-reacting flow, static pressures in low equivalence ratio are similar to those in no fuel injection. As equivalence ratio is increased, static pressures are increased in the duct. In the similar equivalence ratio, static pressures are increased when total enthalpy is decreased. For reacting flow, the flame is occurred near the cavity. The combustion is weak locally in the middle of the duct. The up and down pressure distribution in the duct means that the supersonic combustion is generated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.3
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• pp.654-662
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• 1998

Shift quality of an automatic transmission in a vehicle is mainly affected by transient pressures in the hydraulic system during shifting. In this study, dynamic modelings of the hydraulic system and the power train of an automatic transmission are made systematically by a bond-graph method. The dynamic characteristics of the line pressures and clutch/brake pressures during shiftings are investigated by simulations and verified by experiments. The effects of clutch/brake pressures on the shift torque are also investigated through driving simulation.