• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.103-106
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• 2009

Fracture characteristics of plate shape using shock tube for glass filled ceramics was carried out. Glass filled ceramics have been considered as a promising candidate material for the dome port cover of air breathing engine. This part of the air breathing engine has an important role separating solid and liquid fuel, and needs the frangible characteristics that the fracture of a part should not affect the internal components of combustion. The objectives of this study are to evaluate the fracture pressures for various thicknesses and diameters of shock impact area. Also fracture phenomena of separated membrane using a shock tube are observed. The experimental apparatus of shock tube consists of a driver, a driven section and a dump tank. The used material is glass filled ceramic made from Corning company. Specimens are used 3, 4.5 and 6mm thickness. Also diameters of shock wave area are chosen 70, 60 and 50 mm. It is expected that the results obtained from this study can be used in the basic data for the dome port cover design of an air breathing engine.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.338-343
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• 2008

Fracture characteristics of plates and dome shapes for machinable glass ceramics using compressed shock wave. Machinable glass ceramics have been considered as a promising candidate material for the dome port cover of air breathing engine. This part of the air breathing engine has an important role separating solid and liquid fuel, and needs the frangible characteristics whereby the fracture of a part should not affect the internal components of combustion. The objective of this study are to evaluate the fracture pressure and phenomena of separated membrane using a shock tunnel. The experimental apparatus consists of driver, a driven section and a dump tank. The used material is machinable glass ceramic from Corning company. Specimens are used 3, 4.5 and 6mm thickness with plates and dome shapes. It is expected that the results obtained from this study can be used in the basic data for the dome port cover design of an air breathing engine.

• Korean Chemical Engineering Research
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• v.47 no.3
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• pp.380-385
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• 2009

The absorption rate of carbon dioxide with 2-amino-2-methyl-1-propanol(AMP) was measured in such non-aqueous solvents as methanol, ethanol, n-propanol, n-butanol, ethylene glycol, propylene glycol, and propylene carbonate, and in water at 298 K and 101.3 kPa using a semi-batch stirred tank with a plane gas-liquid interface. The overall reaction rate constant, obtained under the condition of fast reaction regime, from the measured rate of absorption was used to get the elementary reaction rate constants in complicated reactions represented by reaction mechanism of carbamate formation and the order of overall reaction of $CO_2$ with amine. The correlation between the elementary reaction rate constant and the solubility parameter of the solvent was also presented.

• Journal of Chest Surgery
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• v.28 no.8
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• pp.731-741
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• 1995

Cardiac valve allografts have been used as replacements for diseased valves and right ventricular outflow tract reconstruction, the long term follow-up of which has been reported satisfactory. For a good long-term result, it is essential that the allograft be viable at implantation. In this study, we aimed at preparing the cardiac valve allografts aseptically, preserving them at cold- and cryo-conditions, and testing the viability of the allografts after preservation by four methods. We tested the viability of the cardiac valve allografts preserved in cold refrigerated state[4$^{\circ}$C in nutrient media & in liquid nitrogen tank[cryopreservation under -149$^{\circ}$C for pre-planned time periods. The testing methods were 1 glucose utility test 2 tissue culture 3 thymidine uptake test and 4 histologic evidence by light microscopy. We observed no differences in the viability between cold- & cryo-groups and similar results among the methods for testing the viability. In conclusion, there was no difference in the viability between cold- and cryopreserved-allografts at least for 14 days of preservation. And glucose utility test and thymidine uptake test were satisfactory in the evaluation of the allograft viability, since they were easy and rapid with relatively quantitative results.

• Resources Recycling
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• v.31 no.5
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• pp.20-25
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• 2022

In this study, the applicability of microalgae was evaluated for eco-friendly decontamination of cesium-137 (Cs-137) and strontium-90 (Sr-90), which are radioactive nuclides contained in radioactive waste. The monolithic radioactive solution used in the experiment was manufactured at a concentration of 1.5 Bq/mL Cs-137 and 1.0 Bq/mL Sr-90 by diluting a standard radioactive solution and distilled water. This experiment used two types of microalgae, Chlorella Vulgaris was used for Sr-90 decontamination and Hematococcus pluvialis for Cs-137 decontamination. The experimental method is to put the microalgae cultured for 2 weeks into a bottle with a semi-permeable membrane, and then put the bottle in which the microalgae was put into the manufactured radioactive solution, so that the microalgae and the radioactive solution react through the semi-permeable membrane for 48 hours. For the radioactivity concentration analysis of each sample, a gamma-ray nuclide analyzer was used for Cs-137, a γ-ray isotope, and a Liquid Scintillation Count(LSC) was used f or Sr-90, a β-ray isotope. As a result of the experiment, it was confirmed that about 88.0 % of Cs-137 and about 89.7 % of Sr-90 could be decontaminated, and about 98.6 % of Sr-90 was finally able to be decontaminated by the two-stage decontamination method.

• Progress in Superconductivity and Cryogenics
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• v.15 no.4
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• pp.6-9
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• 2013

Korea Superconducting Tokamak Advanced Research (KSTAR) has a helium refrigeration system (HRS) with the cooling capacity of 9 kW at 4.5 K. Main cold components are composed of 300 tons of superconducting (SC) magnets, main cryostat thermal shields, and SC current feeder system. The HRS comprises six gas storage tanks, a liquid nitrogen tank, the room temperature compression sector, the cold box (C/B), the 1st stage helium distribution box (DB#1), the PLC base local control system interconnected to central control tower and so on. Between HRS and cold components, there's another distribution box (DB#2) nearby the KSTAR device. The entire KSTAR device was constructed in 2007 and has been operated since 2008. This paper will present the maintenance result of the KSTAR HRS during the campaign and discuss the operation record and maintenance history of the KSTAR HRS.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.4
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• pp.96-103
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• 2005

The main purpose of launch vehicle is to insert satellite into a target orbit safely and correctly. To accomplish the main purpose of launch vehicle, the inserting velocity, inserting angle, and final mass of launch vehicle should be within the allowable range. In general, such requirements are satisfied with applying TCS(Thrust Control System) and TDS(Tank Depletion System), which manage thrust and mixture ratio by controlling propellant flow rate with thrust and mixture ratio control valves. In this study, the control characteristics of thrust and mixture ratio control valve were examined by PID control logic for stable operation of liquid-Propellant rocket engine at on-dosing point. The analysis on the control characteristics of control valves was done with AMESim code and the results from control valve test facility at KARI.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.4
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• pp.335-342
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• 2019

The objective of this study is to analyze the mechanical properties of plywood used as a thermal insulating material for LNG CCS (Liquefied Natural Gas, Cargo Containment System). It is created by bonding an odd number of parallel and perpendicular direction for preventing contraction and expansion of wood. Also plywood is widely used as LNG CCS insulating material because of its durability, light weight and high stiffness. Since LNG CCS is loaded with liquid cargo, the impact load by sloshing during operation and the wide temperature range (room temperature, low temperature, cryogenic temperature) exposed during loading, unloading should be considered. The thickness of the plywood which is used for the membrane type MARKIII was selected as the thickness of the test specimen. In this present study, plywood is analyzed by the fracture behavior and mechanical properties of plywood by temperature and grain direction. In addition, it is necessary to analyze the fracture shape and predict the fracture strain by using regression model because the critical load may cause cracks inside the tank, which may affect the leakage of cryogenic liquid.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.7
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• pp.862-872
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• 1997

Ice formation in a horizontal circular cylinder has been studied numerically. From the numerical analysis results, it was found that there were three types of freezing pattern and that freezing phenomenon was affected largely by density inversion and cooling rate. The type of freezing pattern largely depends on the secondary flow which is generated by density inversion. When supercooling energy is released before the development of the secondary flow, the annular ice layer grows. If the energy is released when the secondary flow is considerably developed and the supercooled region is removed to the upper half part of the cylinder, an asymmetric ice layer grows. And if the energy is released after perfect development of the secondary flow, instantaneous dendritic ice formation over the full region occurs. Furthermore, this secondary flow was found to have an effect on heat transfer characteristics. The heat transfer rate becomes small at the instant when the secondary flow is generated, but becomes large with the development of the flow. It's concluded that for the facilitation of heat transfer it is desirable to keep water in liquid phase until the secondary flow is perfectly developed. This study gave an instruction of performance improvement of capsule type ice storage tank.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1155-1160
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• 2008

In the present study investigated the heat dissipation characteristics of the natural convection type radiator by using the latent heat from a solid-liquid PCM(Phase Change Material). Total radiator volume size is $423{\times}295{\times}83\;mm$ and PCM tank size is $398{\times}270{\times}26\;mm$. The objective was elapsed time lower than maximum operating temperature. Experimental condition, in order to study the effects of the phase-change phenomenon, carried out the various mass flow rate, input electric power, and heat of fusion temperature of two type PCMs. For the above experimental conditions, the cooling performance by using the latent heat showed that heat absorption rate performs for about 3 hours from using PCM $38^{\circ}C$. However, cooling performance by using PCM $50^{\circ}C$ showed higher than surface temperature of heater block because of heat of fusion.