• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.2
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• pp.68-73
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• 2011

For the launch preparation of KSLV-I, gaseous nitrogen with various level of pressure and cryogenic liquid nitrogen are required. Nitrogen Supply System on launch complex has been developed to perform the production of high pressure gaseous nitrogen, the production of gaseous nitrogen with temperature of 273 ${\pm}$ 2K for protection purge of launch vehicle after loading of propellant and the supply of cryogenic liquid nitrogen for cooling of fuel (kerosene) and oxidizer (liquid oxygen). The operational instability of vaporizer mainly caused by its heat transfer characteristics which sensitively depends on the atmospheric conditions was removed by introducing parallel installation of two vaporizer and their switching operation. The developed Nitrogen Supply System carried out its function successfully in preparation of KSLV-I flight tests.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.752-757
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• 2010

For the launch preparation of KSLV-I, gaseous nitrogen with various level of pressure and cryogenic liquid nitrogen are required. Nitrogen Supply System on launch complex has been developed to perform the production of high pressure gaseous nitrogen, the production of gaseous nitrogen with temperature of $273{\pm}2K$ for protection purge of launch vehicle after loading of propellant and the supply of cryogenic liquid nitrogen for cooling of fuel (kerosene) and oxidizer (liquid oxygen). The operational instability of vaporizer mainly caused by its heat transfer characteristics which sensitively depends on the atmospheric conditions was removed by introducing parallel installation of two vaporizer and their switching operation. The developed Nitrogen Supply System carried out its function successfully in preparation of KSLV-I flight tests.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.2
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• pp.41-47
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• 2017

By using liquid and gaseous nitrogen as simulants, effects of pintle opening distance and simulant supplying condition on spray from pintle injector were investigated qualitatively. The experiment was performed by fixing the liquid supply pressure and varying the opening of the pintle and the supply pressure of gaseous nitrogen. Shadowgraph method with CCD camera was used for image visualization, and the differences of liquid-gas spray were compared by image post processing. In case of liquid nitrogen single injection, as the opening distance was increased, the injection speed was decreased. Therefore, the end of liquid sheet were converged to the center of spray. In the case of liquid nitrogen/Gaseous nitrogen spray, although shadowgraph images look similar to each other, It is shown that it can be analysed by image post processing.

• Journal of Surface Science and Engineering
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• v.51 no.4
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• pp.249-255
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• 2018

High temperature and low temperature gaseous nitriding was performed in order to study of the surface hardening and wear properties of the nitrided AISI 410 Martensitic stainless steels. High temperature gaseous nitiridng (HTGN) was carried out using partial pressure $N_2$ gas at $1,100^{\circ}C$ for 10 hour, and Low temperature gaseous nitiridng (LTGN) was conducted in a gas mixture of NH3 and N2 at $470^{\circ}C$ for 10 hour. The nitrided samples were characterized by microhardness measurements, optical microscopy and scanning electron microscopy. The phases were identified by X-ray diffraction and nitrogen concentration was analyzed by GD-OES. The HTGN specimen had a surface hardness of about $700HV_{0.1}$, $350{\mu}m$ of case depth. A ${\sim}50{\mu}m$ thick, $1,250HV_{0.1}$ hard nitrided case formed at the surface of the AISI 410 steel by LTGN, composed nitrogen supersaturated expanded martensite and ${\varepsilon}-Fe_{24}N_{10}$ iron nitrides. Additionally, the results of the wear tests, carried out LTGN specimen was low friction coefficient and high worn mass loss of ball. The increase in wear resistance can be mainly attributed to the increase in hardness and to the lattice distortion caused by higher nitrogen concentration.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.4
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• pp.775-784
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• 2000

Nitrate dry deposition fluxes were directly measured using knife-leading-edge surrogate surface (KSS) covered with greased strips and a water surface sampler (WSS). The average gaseous flux ($8.3mg/m^2/day$) was much higher than the average particulate one ($3.0mg/m^2/day$). The best fit gas phase mass transfer coefficient (MTC) of $HNO_3$ was obtained by linear regression analysis between measured gaseous flux containing nitrogen compounds and measured ambient $HNO_3$ concentration. The result showed that the MTCs of $HNO_3$ were approximately two times higher than those of $SO_2$. Especially, during the ozone action day, measured gaseous fluxes containing nitrogen compounds were much higher than those ones calculated as the product of measured ambient $HNO_3$ concentration and gas phase MTC of $HNO_3$, which is calculated from MTC of $SO_2$ using Graham's diffusion law. This result indicated that other nitrogen compounds except $HNO_3$ contributed to gaseous flux containing nitrogen compounds into the water surface sampler. The theoretical calculations suggest the contributions of nitrous acid ($HNO_2$) and PAN to the gaseous dry deposition flux of nitrogen containing compounds to the WSS.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.320-329
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• 2008

The influence of thermodynamic transition associated with transcritical nitrogen injection upon the flow structure was investigated to explore numerical simulation of the injectant dynamics of oxygen/hydrogen coaxial jet in liquid rocket engines. Single and coaxial nitrogen jets were treated by comparing the transcritical and perfect-gaseous conditions, wherein the numerical model was accommodative to the real-fluid thermodynamics and transport properties at supercritical pressures. The model was in the first place validated by comparing the results of transcritical nitrogen injection between calculations and available experiments. For a single jet under the transcritical condition, the nitrogen kept a relatively high density up to its pseudo-critical temperature inside the mixing layer, since it remains less expanding until heated up to its pseudo-critical temperature. Numerical analysis revealed that cryogenic jets exhibit strong dependence of specific enthalpy profile upon the associated density profile that are both dominated by turbulent thermal diffusion. In the numerical model, therefore, exact evaluation of turbulent heat fluxes becomes very important for simulating turbulent cryogenic jets under supercritical pressures. Concerning the coaxial jets due to transcritical/gaseous nitrogen injections, the density profile inside the mixing layer was again affected by the thermodynamic transition of nitrogen. However, hydrodynamic instability modes of the inner jet did not show significant differences by this thermodynamic transition, so that further study is needed for the mixing process downstream of the near injection position.

• Asian-Australasian Journal of Animal Sciences
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• v.10 no.5
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• pp.455-459
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• 1997

Fifteen intact male Jamunapari goats, average body weight $22.0{\pm}1.18kg$ were divided into three groups of 5 animals in each to investigate the effects of feeding leucaena on energy retention and distribution of retained energy. Leucaena leaves and twigs provided 0%, 25% and 50% of CP in the rations of animals in $L_1$ (control), $L_2$ and $L_3$ groups, respectively. Energy balances were determined in an open circuit respiration chamber from gaseous exchange and nitrogen carbon balances. Energy retentions calculated from gaseous exchange data were 181.6, 190.0 and 172.8 kJ/kg $W^{0.75}/d$ and from carbon-nitrogen balances were 178.2, 199.5 and 171.1 kJ/kg $W^{0.75}/d$ in $L_1$, $L_2$ and $L_3$ groups, respectively. No significant difference was observed among the groups in both the methods. The retention of nitrogen and energy in the form of protein was similar in different treatment groups. Similarly, no significant effect was observed on energy retention in the form of fat and total energy retention due to incorporation of leucaena in the diets.

• Journal of the Korean Ceramic Society
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• v.15 no.2
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• pp.85-88
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• 1978

Influence of cooling atmosphere on the whiteness in white portland cement was studied. The effective composition of gaseous medium of cooling atmosphere is desirable less than 0.5% of $O_2$ and 0.5~1.5% of CO. When theclinker is quenched in nitrogen atmosphere, the color of clinker becomes bright pink. In a weakly reducing gaseous medium or vacuum, the absence of oxygen brings defects in crystal and transformation in the coordination of iron, and as a result, whiteness is raised.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.185-188
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• 2002

In the design of superconducting power equipments such as transformer, cable and fault current limit, knowledge of the dielectric behavior of both liquid and gaseous at very low temperatures is very importance. Especially, Electrical properties of liquid nitrogen($LN_{2}$) and gaseous nitrogen($GN_{2}$) have become of great interest again since the discovery of high temperature superconductors. However, many sources of $LN_{2}$and $GN_{2}$ problems in the test of pancake coil model arising form the deficiency of insulation data. Therefore, this paper describes the results of an experimental study on the ac breakdown voltage($V_{B}$) properties of $LN_2$ and Air under the electrode of simulated HTS pancake coil. The ac breakdown voltage of $GN_{2}$ have been measured by pancake coil-pancake coil gaps over the temperature range of 293 K to 77 K.

• Journal of Plant Biology
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• v.14 no.3
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• pp.43-46
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• 1971

Losses of nitrogenin the gaseous form were determined with closed systems in the filed under different vegetation types. Ammonia volatilization was greatest from the pine stand, and least from the sod stand, and was greatly reduced in all three sites in the rainy season due to the low temperature. There were only insignificant differences in the nitrogen dioxide volatilization from the soil of the three vegetation types. Losses of ammonia and nitrogen dioxide at various soil depth also showed little variation. Evidently the microbial activity responsible for the $NO_2$ loss was relatively unaffected by the changes in temperature and soil moisture content during the investigation.