• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2008.11a
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• pp.235-238
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• 2008

High-rise buildings with stack effect caused by the foreclosure, which significantly delayed the spread of a fire in effects of these stack effect driving force said. In this research on the stack effect of the lobby if the pressurization of the stairwell analysis of the pressure distribution of the CONTAMW. Overall, the pressurization of the lobby makes it stairwell amount of pressure(+) to the zone in pressure designed to prevent the spread of smoke control performance and found that, the way a normal state and sub-pressurization in the stairwell with stack effect of the turbulence Such as the formation of the upper flow, but, in the upper atmosphere with pressurization was formed by the underlying trend.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.795-800
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• 2000

A CCFL(Counter Current Flow Limit) test have been performed in narrow annular gaps with large diameter, because it has been confirmed that the CCFL phenomena affected the critical power in hemispherical narrow gap geometries from the SONATA(Simulation Of Naturally Arrested Thermal Attack)-IV (In-Vessel)/VISU(Visualization)-II experiments. The objectives of the CCFL experiments are to investigate the small gap sizes(1, 2mm) effect on CCFL under the large diameter condition and to confirm the findings of the VISU-II study that global dryout in hemispherical narrow gaps was induced by the CCFL. The test section was made of acrylic resin to allow visual observation on the two-phase flow behaviors inside annular gaps. It was observed from visualization that a part of water supplied was accumulated in the upper plenum and a significant increase in the differential pressure across the gap was occurred, which was the definition of the CCFL occurrence in this experimental study. From the experimental results in annular gap with large diameter it can be known that an increase in the differential pressure was not big at small air flow-rates. When the CCFL was occurred, the differential pressure across gaps was increased significantly and a water accumulated in the upper plenum. The occurrence of CCFL was correlated using the Wallis parameter.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.591-593
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• 2006

The differential pressure method has been used in the level measurement of steam generator in nuclear power plant. Two sensing lines from a steam generator to a pressure transmitter are needed to measure the high pressure and low pressure. The fluid conditions in the sensing line require the uniform phase with no bubbles and the slope of sensing line should be installed with forward slope. The expansion of the bubble volume according to the upper pressure and the reverse slope of sensing lines explain how the level errors took place.

• Fire Science and Engineering
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• v.22 no.3
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• pp.194-200
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• 2008

In order to design and operate successfully the pressure differential system for smoke control which uses difference of pressure between compartments of building, architectural factors affecting the pressure field of building should be examined and the stack effect is one of the important factors. The field experiments on pressure field in two buildings of 21 stories and 31 stories in summer and winter season with regard to on/off condition of the pressure differential system are carried out to evaluate the influence of stack effect to evacuation and smoke management of high-rise building. In winter season when the stack effect increases, as the pressure differential system starts to operate, the pressure in upper stair rises largely due to the combination effect of the air infiltration from lobby to stair and the stack effect.

• Advances in nano research
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• v.13 no.1
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• pp.77-86
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• 2022

This paper studied the peristaltic transport of upper convected Maxwell nanofluid through a porous medium in a heated (isothermal) symmetric vertical channel. The nanofluid is assumed to be electrically conducting in the presence of a uniform magnetic field. These phenomena are modeled mathematically by a differential equations system by taking low Reynolds number and long-wavelength approximation, the yield differential equations have solved analytically. A suggested new technique to display and discuss the trapping phenomenon is presented. We discussed and analyzed the pumping characteristics, heat function, flow velocity and trapping phenomena which were illustrated graphically through a set of figures for various values of parameters of the problem. The numerical results show that, there are remarkable effects on the vertical velocity, pressure gradient and trapping phenomena with the thermal change of the walls.

• Plant Journal
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• v.6 no.2
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• pp.70-77
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• 2010

This study investigated the characteristics of co-combustion of mixed anthracite (domestic and Vietnam) and bituminous coal (Sonoma, Australia) at circulating fluidized bed boiler in Donghae thermal power plant when mixing ratio of bituminous coal is variable. Co-combustion of bituminous coal contributes to improvement in general combustion characteristics such as moderately retaining temperature of furnace and recycle loop, reducing unburned carbon powder, and reducing discharge concentration of NOx and limestone supply owing to improvement in anthracite combustibility as the mixing ratio was increased. However, bed materials were needed to be added externally when the mixing ratio exceeded 40% because of reduction in generating bed materials based on reduction in ash production. When co-combustion was conducted in the section of 40 to 60% in the mixing ratio while the supplied particles of bituminous coal was increased from 6 mm to 10 mm, continuous operation was shown to be possible with upper differential pressure of 100 mmH2O (0.98 kPa) and more without addition of bed materials for the co-combustion of mixed anthracite and bituminous coal (to 50% or less of the ratio) and that of domestic coal and bituminous coal (to 60% of the ratio).

• Journal of Korea Association of Health Promotion
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• v.1 no.1
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• pp.21-25
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• 2003

Vomiting in pediatric patient is frequently encountered problem in emergency room or outpatient clinic. In differential diagnosis, age of the patient or accompanying symptoms should be considered in the differential diagnosis. Accurate diagnosis is very important because surgical treatment is necessary in some of the conditions. Imaging diagnosis of conservative modality such as upper gastrointestinal series or colon study is still important radiological examination in the initial differential diagnosis, but recently ultrasonography offers accurate diagnosis in many situations. The cause of vomiting in pediatric are diverse according to the age group :neonatal sepsis, necrotizing enterocolitis, or hypertrophic pyloric stenosis in neonates : gastroesophageal reflux, viral enteritis, or intussusception in infant: midgut volvulus, appendicitis, metabolic disorders, or increased intracranial pressure also an be the cause. knowledge of radiological findings of normal gastrointestinal tract is important to recognize abnormalities. A discussion of radiological findings in variable surgical conditions to present as vomiting in pediatric patients is offered.

• Fire Science and Engineering
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• v.24 no.5
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• pp.79-86
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• 2010

In this study, we confirmed the fact that air egress velocity of pressure differential system which is installed in vestibule of smokeproof stairway in domestic high-rise building becomes back-flow into the vestibule not into the livingroom when the doors open to escape in case of fire by actual measurement. It concerned that fire smoke inflow into the vestibule of smokeproof stairway. so, reflux symptoms were developing the condition does not occur by creating an area of $2m^2$ and a model. if it‘s area is less, airflow in upper area was severely reflux. in the case upward 45 gradient of supply damper’s angle of blade, The results that reflux symptoms include upper door but bottom has some reflux. also vestibule of smokeproof stairway‘s area of $4m^2$ in the living room door in the direction of the flow distributon was normal. if a vestibule of smokeproof stairway is smaller, it designed to be performance-based design should be.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.1 no.2
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• pp.190-201
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• 1989

This experimental investigation has been conducted to determine the effects of swirling angle and flow patterns on distributions of void fraction, bubble velocity and two-phase pressure drop in a vertical straight tube. Swirling angles of $0^{\circ}$ (non swirling), $30^{\circ}$, and $45^{\circ}$ were tested with air-water two components over a range of superficial air velocities. A transparent lucite tube of 38mm in internal diameter was used for the test section. The void fraction and bubble velocities were measured by means of a optical fiber probe at the upper part of the swirler in the test section. Pressure drops which seem to be closely related with flow patterns and swirling angle were measured by a differential pressure transducer. It is shown that the probability density functions of pressure drop demonstrate peculiar features for both swirling angles and flow patterns, whereas the distributions of void fraction and bubble velocities are parabolic and flat shape in the vicinity of tube center, respectively except bubbly flow in any swirling angle cases, and the void fraction increases with increasing swirling angle around the center of tube.

• Journal of the Korean Geosynthetics Society
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• v.22 no.1
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• pp.87-96
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• 2023

There are a lot of difference between the surface settlement and the differential settlement measured at the Busan New Port, where the dredged and reclaimed clay layer exists and below the clay is originally thickly distributed. To find the cause and solution of this, the actual conditions of each differential settlement used for the soft ground improvement, characteristics, installation method, measurement frequency, measurement data management, and data analysis of each type were considered. In the deep soft ground improvement work where large deformation occurs, the bending deformation of the screw-type differential settlement gauge is less than that of other types of measuring instruments, so there is less risk of loss, and the reliability of data is relatively high as the instruments are installed by drilling for each stratum. Since the greater the amount of high-precision settlement measurement data, the higher the settlement analysis precision. It is necessary to manage with higher criteria than the measurement frequency suggested in the standard specification. For the data management of the differential settlement gauge, it is desirable to create graphs of the settlement and embankment height of the relevant section over time, such as surface, differential, and settlement of pore water pressure gauge for each point. In the case of multi-layered ground with different compression characteristics, it is more appropriate to perform settlement analysis by calculating the consolidation characteristics of each stratum using a differential settlement data.