• Proceedings of the KSME Conference
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• 2005.11a
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• pp.91.1-91.1
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• 2005

• 한국전산유체공학회:학술대회논문집
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• 2001.05a
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• pp.116-120
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• 2001

The impactive Pressure wave induced by pyro valve in the pressurization system of KSR-III may result in fatal failure or malfunction of valves, so it is important to know the pressure wave characteristic in the pressurization system. An unsteady flow analysis in the simplified pressurization system was peformed by Finite difference method.

• Fire Science and Engineering
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• v.30 no.5
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• pp.87-92
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• 2016

Amid the growing number of high-rise complex buildings in Korea, efficient smoke prevention technology in a fire is required and as an alternative of a mechanical smoke control system in high-rise buildings, the use of a smoke control system using sandwich pressurization has been on the rise. In such a system, the appropriate pressure difference and the data for designing the air supply and exhaust flow rate are necessary to prevent the spread of smoke and offer a tenable evacuation environment. As part of such effort, this paper presents a field test process and result after testing a building where such a smoke control system using sandwich pressurization has been installed. A ventilation rate of 6 cycles per hour were applied to simulate the air exhaust flow rate on a fire floor and the air supply flow rate on the floors above and below the fire floor. As a result of the system operation, pressure difference of approximately 260 Pa between the 12th floor of a fire and the 13th floor was generated. The over pressure of the experiment has a serious effect on the evacuation or fire compartment so that it is necessary to examine the improvement.

• The Journal of the Convergence on Culture Technology
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• v.6 no.1
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• pp.477-483
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• 2020

The rehabilitation methods used in existing concrete box structures rely on the method of attaching the repair material to the section of the structure with a spray equipment. In the case of ceiling or wall parts, the adhesion force to the repair material may be reduced by the gravity and dead load after construction. In subway structures, vibration causes a problem that reduces the initial adhesion. Supplementary measures are needed as the quality of repair varies depending on the worker's proficiency and construction environment. In this study, mechanical pressurization equipment was developed that can apply a certain pressure after construction of a repairwork to solve problems such as reduction of adhesion of repair materials by gravity and variation of repair quality by labor work. To find out the effect of the pressurized equipment, a chamber similar to the field conditions was constructed to measure the attachment strength different from the pressurized condition, the section, and the environmental conditions. The pressurization differed from the other parts, but the adhesion strength of up to 70% was increased.

• Transactions of Materials Processing
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• v.16 no.4 s.94
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• pp.239-243
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• 2007

Superplastic forming/diffusion bonding(SPF/DB) has been widely used in the automotive and aerospace industry since it has great advantages to produce very light and strong components. Finite element method(FEM) is used to model the SPF/DB process of 3-sheet sandwich panel to predict the pressure-time curve and to analyze the process parameters. In order to eliminate defects of the part, a new pressurization scheme is proposed. Contrary to the conventional one-step pressurization, which causes the folding at the DB joint, two-step pressurization can eliminate the folding. Effect of pressurization cycle was investigated by using FE analysis and proper pressurization cycle is proposed.

• Fire Science and Engineering
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• v.25 no.6
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• pp.178-183
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• 2011

In cold season, the elevator systems in super high-rise buildings would make noises at the door-gaps on high floors, and the elevator doors on the 1st floor would suffer from opening/closing trouble due to the pressure differences. Such pressure differences are also the main driving power of smokes through the hoistway in the case of fire. In addition, the pressure differences should be overcome to use the elevator systems as a measure of emergency escape. This paper reviews the way of hoistway pressurization to reduce the adverse influences. Simulations achieved a good result close to the requirements of NFPA 92A and IBC 2012 under the condition that the hoistway should be pressurized after pressure equalizing between floors and hoistway with the openings through the hoistway wall.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.12
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• pp.1202-1208
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• 2010

The prediction of the required pressurant mass for maintaining the pressure of propellant tanks during propellant feeding is an important issue in designing pressurization system. The temperature of pressurant fed into propellant tank is the critical factor in the required pressurant mass and is one of the most crucial design parameters in the development of pressurization system including designing the weight of pressurant tanks and the size of heat exchanger. Hence a series of propellant drainage tests by pressurizing propellant stored in a cryogenic propellant tank have been performed with measuring the temperature distribution inside ullage and the required pressurant mass according to the temperature condition of pressurant. Results shows that the required pressurant mass decreases as the temperature of pressurant increases. However, the rate of the actual pressurant mass to the ideal required pressurant mass increases.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.12
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• pp.850-856
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• 2007

In a supercooled or capsule type ice storage system, aqueous solution (or water) may have trouble with non-uniform dissolution though the system contributes to the simplicity of system and ecological improvement. The non-uniform dissolution increases the instability of the system because it may cause an ice blockage in pipe or cooling part. In order to observe the supercooled state, a cooling experiment was performed with pressurization to an ethylene glycol(EG) 3 mass% solution in stationary state. Also, the effect of the pressurization from 101 to 505 kPa to the dissolution of supercooled aqueous solution was measured with the dissolution time of the supercooled aqueous solution at a fixed cooling rate of brine. At results, the dissolution of supercooled point decreased as the pressure of the aqueous solution in the vessel increased. Moreover, the dissolution point increased as the heat flux for cooling increased.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.7
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• pp.596-602
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• 2006

Ice adhesion and blockage problems have been issued in continuous ice slurry making process. So we composed continuous ice slurry making device using a commercial small plate heat exchanger (PHX), and investigated character of ice formation. An experiment of ice formation was peformed with an aqueous solution of ethylene glycol 7 mass%. In the experiment, the effect of the pressurization on ice slurry formation during the cooling process was investigated. The pressurization test for the aqueous solution was performed by setting valves at the PHX inlet and outlet. At the results, the time of continuous ice formation increased as the pressure of the plate heat exchanger increased for cooling temperature of $-5^{\circ}C$. Also continuous ice formation at the cooling temperature of $-7^{\circ}C$ showed a possibility. It was found that the pressurization may contribute to suppress the dissolution of supercooled aqueous solution in the PHX.

• Aerospace Engineering and Technology
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• v.10 no.1
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• pp.54-62
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• 2011

The pressurant mass required for propellant tank pressurization with operating condition variation was estimated by using the numerical model already developed for this purpose. The model was applied to the concept design results of KSLV-II first stage oxygen tank. The supplied pressurant temperature, oxygen volumetric flow rate, and the ratio of length to diameter of the tank were selected as variables. The required pressurant mass and mass flow rate, collapse factor, ullage temperature distribution were predicted, and the results showed that the pressurant temperature had the largest effect on the amount of the required pressurant mass. The pressurizing efficiency of the propellant tank was calculated through analyzing energy distribution in the ullage. It was found that the gas-to-wall heat transfer in the ullage was dominant, and much of the pressurant energy was lost to tank wall heating.