• Korean Journal of Food Science and Technology
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• v.36 no.4
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• pp.655-661
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• 2004

Sphingolipid production was investigated through Ganoderma lucidum-submerged cultivation. Crude sphingolipid obtained from G. lucidum was purified by methanol precipitation, Dowex AG DW-X8 (H+ form) cation exchange chromatography, and preparative thin layer chromatography, Structure and functionalities of purified sphingolipid were elucidated including cutaneous hydration effect. Possibility of use as cosmetics material and new biomaterial was explored. Production was 0.4 g/L at 1% yield. Purified sphingolipid was identified as D-ribo-1,3,4-trihydroxy-2-aminoocta decan through UV/VIS, FT-IR, and $^1H-NMR$. Sphingolipids increased skinmate value for cutaneous hydration effect by 20% at $500\;{\mu}g/mL$ and decreased skin roughness at $100\;{\mu}g/mL$. Results suggest shingolipids from G. lucidum are effective for cutaneous hydration and improvement of skin roughness.

• Journal of the Korean Wood Science and Technology
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• v.45 no.3
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• pp.268-277
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• 2017

In this study, lignocellulose nanofibrils (LCNFs) were prepared from Pussy willow wood powder by disk-milling after pretreatment using the cosolvent of 1-ethyl-3-methylimidazolium acetate ([EMIM]Ac) and N,N-dimethylformamide (DMF) with different mixing ratios for different time. All pretreated samples showed native cellulose I polymorph and cellulose crystallinity was lowest when cosolvent of DMF with 30% [EMIM]Ac was used. Average crystallite size of raw material and the pretreated product by MDF and its cosolvent with 10% [EMIM]Ac was found to be about 3.2 nm and decreased with increasing pretreatment time at the DMF cosolvent with 30% [EMIM]Ac. Defibrillation efficiency was improved by loosening wood cell wall structure by the pretreatment using co-solvent system of [EMIM]Ac and DMF.

• Journal of the Korean Institute of Gas
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• v.5 no.4 s.16
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• pp.85-91
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• 2001

This paper presents safety analysis of LNG leakage in a prestressed concrete outer tank, which is strongly related on the leak checking effects of the PC structure with and without a residual compression zone based on the BS 7777 codes. The full containment type outer tank which is constructed by a prestressed concrete may be destroyed by leaked cryogenic fluids. The FE calculated results show that the total leak checking time of the PC structure with $10\%$ residual compression zone is about 9 days for $-162^{\circ}C$ liquids. But, three primary pumps in an inner tank may operate to send cryogenic fluids for 6 days, which are stored in an inner tank of $140,000m^3$ capacity This means that the prestressed concrete outer tank may be safe for $-162^{\circ}C$ cryogenic fluids leaked from the demolished inner tank.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.2
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• pp.155-163
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• 2014

At gas stations, liquid fuels expand and contract in volume owing to temperature variations. In Korea, the ambient temperature varies between $-15^{\circ}C$ in winter and $35^{\circ}C$ in summer. The volume expansion coefficients of liquid fuels are about $0.1%/^{\circ}C$. To investigate this issue, we measured daily changes in fuel temperature and the delivered fuel temperature at gas stations. In addition, we scrutinized the daily, monthly, and annual changes in temperature over past 50 years in Korea. The results show that the temperature of the fuel in the storage tank was maintained at a stable value(summer or winter). Many factors, such as the surrounding conditions, fuel filling frequency, and gas station location, influence the delivered fuel temperature. The results of this study can be applied for establishing a national regulation and will contribute to fair transactions.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.9
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• pp.913-917
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• 2008

Since the difficulty of analysis at low concentration and the uncertainty of the removal mechanism for Nitrosodimethylamine (NDMA) have been reported, this study has detected extremely low concentration $^{14}$C-NDMA using the LSC(Liquid Scintillation Counter) and tested NDMA removal by Powdered Activated Carbon(PAC). The results showed the highest correlation over 99% when samples were measured with the mixture ratio of sample to scintillation liquid of 10 : 10 and at the detection time of 10 min. For $^{14}$C-NDMA removal by the PACs(S-A(Sigma-Aldrich co.) and Dj(Daejung co.)) raging from 50$\sim$10,000 mg/L, $^{14}$C-NDMA was removed over 90% by adsorption treatment. In addition, S-A showed twice greater adsorption capacity than that of Dj. However, the required PAC amount for $^{14}$C-NDMA removal was higher than that of other amine compounds.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.116-121
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• 2006

The pressurization system in a liquid rocket propulsion system provides a controlled gas pressure in the ullage space of the vehicle propellant tanks. It is advantage to employ a hot gas heat exchanger in the pressurization system to increase the specific volume of the pressurant and thereby reduce over-all system weight. Therefore a significant improvement in pressurization system performance can be achieved, particularly in a cryogenic system. For this study air and $CN_2$ are employed as external fluid and pressurant respectively Numerical analysis on the pressurant discharging characteristics have been compared with the experimental results performed at the PTF(Propellant-feeding Test Facility). It is shown that the discrepancy of analytic and experimental results is within about ${\pm}15%$. It is estimated that the temperature drop rate of cryogenic pressurant immersed liquid oxygen can be predicted using this analytic approach method.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.71-75
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• 2009

Test results of combustion chamber to verify the operation and the combustion performance at low pressure, design and off-design conditions for 30ton-class liquid rocket engine were described. The combustion chamber has nominal chamber pressure of 60 bar, propellant mass flow rate of 89 kg/s, and nozzle expansion of 12. Effects of chamber pressure on combustion characteristic velocity are largely affected by mixture ratio. The specific impulse of combustion chamber is proportional to the chamber pressure regardless of the mixture ratios. The present results can be used as the base to predict the combustion performance of large sized chamber at high pressure while demonstrating the possibility of low pressure firing test of large sized chamber.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.69-73
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• 2009

Combustion test results of 1/2.5-scale thrust chamber for 75tonf-class liquid rocket engine were described. The thrust chamber has chamber pressure of 60 bar, propellant mass flow rate of 89 kg/s, and nozzle expansion ratio of 12. The combustion tests were conducted to verify the combustion performance, the regenerative cooling performance and the durability of thrust chamber at design point condition, and then were performed to confirm the operation and the combustion performance at low combustion pressure condition. All the tests had been successfully executed without the damage of the hardware. These test results present a possibility of hot firing test at low combustion pressure condition, and can be used as fundamental data to predict the combustion performance at design point condition for 75 tonf thrust chamber.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.1
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• pp.89-96
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• 2013

Combustion pressures were measured to study combustion stability for an oxygen rich preburner by both of static and dynamic pressure sensors. The resolutions of each static and dynamic pressure sensor are the 1,000 Hz and 25,600 Hz, respectively. The nominal combustion pressure of the preburner was 200 bar but 80 bar was used at the several initial tests for the safety reason. Two stage ignition was applied to reduce the ignition impact for every tests including the tests with 200 bar combustion pressure. The tests lasted for 10 sec. max. and a little fluctuations of pressure was observed during the main mode. The measured pressures were studied by FFT analysis and no noticeable frequency coupling was found. Thus the preburner can be regarded as stable and it can be utilized for further study on staged combustion cycle liquid rocket engine.

• Journal of Energy Engineering
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• v.2 no.2
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• pp.179-186
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• 1993

Heat pipes. applied to a flat plate solar collector, have a long and slender configuration with relatively low heat flux in the evaporator section. Such a heat pipe has a tendency to build-up a liquid pool at the lower part of the evaporator section. and at this pool occurs such complicated phenomena of evaporation and fluid dynamics as superheat, sudden generation of bubble, its likely explosive growth process and flooding, etc. In the present study. we tried to solve these problems by means of adjusting two principal design parameters, the liquid inventory and the installation region of the wick, using 4 heat pipes and 3 thermospheres. The corresponding results can be summarized as follows$\^$1)/. The effective thermal conductances of the heat pipe was greatly improved by eliminating the wick in the adiabatic and condenser sections$\^$2)/. The liquid inventory should be increased by about 40% larger than what is saturated the wick$\^$3)/. In the evaporator section the wick has a favorable effect to reduce both unstable operation by intermittent occurrence of nucleate boiling and response time at the initial start-up process.