• Resources Recycling
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• v.26 no.1
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• pp.22-29
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• 2017

When the ambient air pressure was $0.1kg/cm^2$, there were few spherically formed droplets, which showed very badly fragmented state. The average particle size of the particles constituting the droplet was about 40 nm. When the air pressure increased to $0.5kg/cm^2$, the ratio of the spherical droplet forms increased, but still showed a state of severe disruption. The average particle size of the particles was reduced to about 35 nm. As the air pressure increased to $3kg/cm^2$, the ratio of spherical droplet form significantly increased, the degree of fragmentation even further decreased and the average particle size decreased to 30 nm. When the air pressure increased from 0.1 to $1kg/cm^2$, the XRD peak intensity showed little change, but the specific surface area was decreased. As the air pressure increased to $3kg/cm^2$, the intensity of XRD peaks showed a little decrease, while the specific surface area increased.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.06a
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• pp.134-141
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• 2000

The real area of contacts, average film thickness, mean real pressure, and mean hydrodynamic pressure are investigated numerically in this study, especially for the parallel thrust bearing. Model surface is generated numerically with given autocorrelation function and some surface profile parameters. Then the average Reynolds equation contained flow factors and contact factor is applied to predict the effects of surface roughness in mixed lubrication regimes. In this equation, flow factors are defined as correction terms to smooth out high frequency surface roughness and contact factor is introduced to relieve from obtaining the average film thickness. Therefore the computation time to obtain h can be reduced.

• Tribology and Lubricants
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• v.16 no.6
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• pp.455-460
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• 2000

The real area of contacts, average film thickness, mean real pressure, and mean hydrodynamic pressure are investigated numerically in this study, especially for the parallel thrust bearing. Model surface is generated numerically with given autocorrelation function and some surface profile parameters. Then the average Reynolds equation contained flow factors and contact factor is applied to predict the effects of surface roughness in mixed lubrication regimes. In this equation, flow factors are defined as correction terms to smooth out high frequency surface roughness and contact factor is introduced to relieve from obtaining the average film thickness. Therefore the computation time to obtain barh h can be reduced.

• Journal of Chest Surgery
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• v.23 no.4
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• pp.659-666
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• 1990

We evaluated 68 patients with mitral valve disease who underwent mitral valve replacement from April, 1986, to December, 1988. Among them 20 patients showed increased systolic pulmonary arterial pressure greater than 60 mmHg and postoperative hemodynamic data were obtained in 19 patients average 13 months after mitral valve replacement. The results were as followings. 1. Average pulmonary systolic pressure decreased from 84.8$\pm$4.5 preoperatively to 33. 0$\pm$1.9mmHg postoperatively[P<0.001]. 2. Average pulmonary vascular resistance index decreased from 1425$\pm$148 preoperatively to 287+35.8 dyne * sec * cm2 * m postoperatively[P<0.001]. 3. Average cardiac index rose from 1.927$\pm$0.169 preoperatively to 2.625$\pm$0.159 L/min/m2 postoperatively [P <0.005]. This study shows that pulmonary hypertension and the increased pulmonary vascular resistance index due to mitral valve disease can regress significantly after mitral valve replacement.

• Magazine of the Korean Society of Agricultural Engineers
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• v.35 no.1
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• pp.29-39
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• 1993

A model for estimating daily effective rainfall of upland crops was developed. The infiltration process was described by Green-Ampt infiltration model developed by Chu(1978). The model considers delayed surface ponding and surface detention storage under a uniform soil profile. The Green-Ampt parameters, that is, average hydraulic conductivity and average capillary pressure head on a sandy loam soil were determined from field experiment using Air-entry permeameter developed by Bouwer(1966). The model was verified by comparing measured and simulated surface runoff. The ratios of effective rainfall to total rainfall for red pepper, soybean, sesame and Chinese cabbage were evaluated using Borg's root growth model( 1986) respectively. The followings are a summary of this study results; 1.In a sandy loam soil average hydraulic conductivity was 3.28cm/hr and average capillary pressure head was 3.00cm. 2.The root growth of upland crops could be expressed by Borg's root growth model successively. 3.The measured and simulated surface runoff was agreed well with each other. 4.As the rainfall amount was increased, the ratio of effective rainfall to total rainfall was decreased exponentially till a certain growing period.

• Archives of Plastic Surgery
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• v.49 no.2
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• pp.275-284
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• 2022

Background Population aging has led to an increased incidence of pressure ulcers, resulting in a social burden and economic costs. We developed a three-dimensional knitted fabric (3-DKF) with a pressure-reducing function that can be applied topically in the early stages of pressure ulcers to prevent progression. Methods We evaluated the effects of the 3-DKF in a streptozotocin-induced diabetes mellitus pressure ulcer mouse model, and the fabric was preliminarily applied to patients. Twelve-week-old male C57BL/6 mice were used for the animal experiments. In the pressure ulcer mouse model, an ischemia-reperfusion injury was created using a magnet on the dorsa of the mice. Pressure was measured with BodiTrak before and after applying the 3-DKF to 14 patients at risk of sacral pressure ulcers. Results In the 3-DKF-applied mice group, the ulcers were shallower and smaller than those in the control group. Compared with the mice in the control group, the 3-DKF group had lower platelet-derived growth factor-α and neutrophil elastase expression, as parameters related to inflammation, and increased levels of transforming growth factor (TGF)-β1, TGF-β3, proliferating cell nuclear antigen, and α-smooth muscle actin, which are related to growth factors and proliferation. Additionally, typical normal tissue staining patterns were observed in the 3-DKF group. In the preliminary clinical analysis, the average skin pressure was 26.2 mm Hg before applying the 3-DKF, but it decreased to an average of 23.4 mm Hg after 3-DKF application. Conclusion This study demonstrated that the newly developed 3-DKF was effective in preventing pressure ulcers through testing in a pressure ulcer animal model and preliminary clinical application.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.11a
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• pp.301-306
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• 1996

To predict the average liquid level under the condition of the countercurrent stratified two-phase flow in a pipe, an analytical model has been suggested. This is made by introducing the interfacial level gradient into the liquid-phase and the gas-phase momentum equations. The analytical method for the gas-phase pressure drop calculation with f$_i$ $\neq$ f$_G$ has also been described using the liquid level prediction model developed in the present study.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.1
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• pp.38-46
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• 2006

The characteristics about the pressure drop in microtubes have been investigated. The test tubes are the circular, seamless, stainless steel tubes with an inner diameter of 0.244, 0.430, and 0.792 mm, respectively. R-l34a was used as a test fluid. Early flow transition which has been reported in some previous studies is not found in single-phase flow pressure drop tests. The conventional theory between friction factor and Reynolds number predicted the experimental friction factors within an absolute average deviation of $8.9\%$. The two-phase flow pressure drop increases for higher quality and mass flux, and for reduced inner diameter. The existing correlations fail to predict the experimental data. A new correlation to predict the two-phase flow pressure drop is developed in the form of the Lockhart-Martinelli correlation. The effects of the tube diameter and the surface tension were considered, and the correlation predicted the experimental data within an average absolute deviation of $8.1\%$.

• Journal of Soil and Groundwater Environment
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• v.21 no.6
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• pp.128-134
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• 2016

Acoustic emission spectra was analyzed to investigate the distribution of sound pressure in a 36 kHz sonoreactor. The sound pressure of fundamental frequency (f: 36 kHz), harmonics (2f: 72 kHz, 3f: 108 kHz, 4f: 144 kHz, 5f: 180 kHz, 6f: 216 kHz), and subharmonics (1.5f: 54 kHz, 2.5f: 90 kHz, 3.5f: 126 kHz, 4.5f: 162 kHz, 5.5f: 198 kHz, 6.5f; 234 kHz) was measured at every 5 cm from the ultrasonic transducer using a hydrophone and a spectrum analyzer. It was revealed that the input power of ultrasound, the application of mechanical mixing, and the concentration of SDS affected the sound pressure distributions of the fundamental frequency and total detected frequencies frequencies significantly. Moreover a linear relationship was found between the average total sound pressure and the degree of sonochemical oxidation while there was no significant linear relationship between the average sound pressure of fundamental frequency and the degree of sonochemical oxidation.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.6
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• pp.210-217
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• 1998

This paper describes the method for detection of the misfired cylinder using the pressure fluctuations occurred in the exhaust system on an MPI gasoline engine. If misfire is occurred in the cylinder of the gasoline engine, the power of engine gets lost, the fuel consumption and the exhaust emission are increased and the vibration is caused by unsteady torque. Therefore early detection and correction of misfire play a very important role in the proper performance and the exhaust emission. This paper suggests method of misfire detection which affect engine performance. The method is a comparison of average pressure index during the displacement period. Experimental results showed that the method using the pressure fluctuations in the exhaust system is proven to be effective in the detection of misfire on gasoline engine regardless loads and revolutions of the engine. In addition, this method, using the pressure fluctuations in exhaust system is easier than other methods and is not a need of additional reconstruction of engine.