• Progress in Superconductivity and Cryogenics
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• v.7 no.4
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• pp.4-9
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• 2005

The degradation behavior of the critical current $(I_c)$ of Bi-2223 superconducting tapes under pressurized liquid nitrogen were investigated using a newly developed p-shaped sample holder which gives a series of bending strains to a sample. Three kinds of commercially available multi-filamentary Bi-2223 superconducting tapes were used. At atmospheric pressure, the Ie degradation behavior depended on the manufacturing process undergone by each tape. The tapes externally reinforced or densified by over pressure showed better bending strain tolerance than the Ag alloy-sheathed Bi-2223 tape. But these tapes showed a significant $I_c$ degradation when pressurized to 1 MPa in liquid nitrogen. For all samples, after depressurization to atmospheric pressure from 1 MPa, the Ie was completely recovered to its initial values at atmospheric pressure. When the samples were subjected to a thermal cycle wherein the tape was warmed up to room temperature after being depressurized from 1 MPa, it was found that the larger degradation of $I_c$ occurred at the regions where significant ballooning occurred, such as $0\%\;and\;0.2\%$. However, an improved ballooning damage tolerance was observed in the highly-densified tape.

• Journal of Korean Biological Nursing Science
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• v.4 no.2
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• pp.41-49
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• 2002

Aim To evaluate blood pressure, blood glucose and serum lipid level in obese and nonobese type 2 diabetic patients. Methods 206 obese(76 male, 130 female) and 442 nonobese(208 male, 234 female) type 2 diabetic patients underwent fasting blood glucose, 2-hour postprandial blood glucose, $HbA_1c$ total cholesterol, triglyceride, high density lipoprotein, microalbuminuria, blood urea nitrogen, creatinine and C-peptide were measured. Diabetes was diagnosed according to the American Diabetes Association(ADA)criteria. Obesity was defined as body mass index(BMI, kilograms per meters squared)${\geq}25$. Results In male, systolic blood pressure, triglycerides, microalbuminuria and C-peptide were significant higher in obese than nonobese patients. Fasting blood glucose were significantly lower in obese than nonobese patients. Diastolic blood pressure, 2-hour postprandial blood glucose, $HbA_1c$, total cholesterol, high density lipoprotein, blood urea nitrogen, and creatinine were no difference between 2 groups. In female, triglycerides and C-peptide were significant higher in obese than nonobese patients, Blood pressure, fasting blood glucose, 2-hour postprandial blood glucose, $HbA_1c$, total cholesterol, high density lipoprotein, microalbuminuria, blood urea nitrogen, and creatinine were no difference between 2 groups. Conclusion Our present study supports that increased triglycerides play a major role in increasing the risk of coronary heart disease(CHD) in obese women type 2 diabetic patients.

• Progress in Superconductivity and Cryogenics
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• v.16 no.2
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• pp.64-69
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• 2014

Measuring an exact amount of remaining cryogenic liquid propellant under microgravity condition is one of the important issues of rocket vehicle. A Pressure-Volume-Temperature (PVT) gauging method is attractive due to its minimal additional hardware and simple gauging process. In this paper, PVT gauging method using liquid nitrogen is investigated under microgravity condition with parabolic flight. A 9.2 litre metal cryogenic liquid storage tank containing approximately 30% of liquid nitrogen is pressurized by ambient temperature helium gas. During microgravity condition, the inside of the liquid tank becomes near-isothermal condition within 1 K difference indicated by 6 silicon diode sensors vertically distributed in the middle of the liquid tank. Helium injection with higher mass flow rate after 10 seconds of the waiting time results in successful measurements of helium partial pressure in the tank. Average liquid volume measurement error is within 11% of the whole liquid tank volume and standard deviation of errors is 11.9. As a result, the applicability of PVT gauging method to liquid propellant stored in space is proven with good measurement accuracy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.532-534
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• 2000

Si thin films on p-type (100) Si substrate have been fabricated by pulsed laser deposition technique using a Nd:YAG laser. The pressure of the environmental gas during deposition was varied from 1 to 3 Torr. After deposition, Si thin film has been annealed again at nitrogen ambient. Strong violet-indigo photoluminescence have been observed from Si thin film annealed in nitrogen ambient gas. As increasing environmental gas pressure, weak green and red emissions from annealed Si thin films also observed by photoluminescence.

• 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.

• Transactions of Materials Processing
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• v.28 no.1
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• pp.43-48
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• 2019

Aluminum nitride (AlN) is used by the semiconductor industry, and is a compound that is required when manufacturing high thermal conductivity. The AlN films with c-axis orientation and thermal conductivity characteristic were deposited by using the Pulsed Laser Deposition (PLD). The AlN thin films were characterized by changing the deposition conditions. In particular, we have researched the AlN thin film deposited under optimal conditions for growth atmosphere. The epitaxial AlN films were grown on sapphire ($c-Al_2O_3$) single crystals by PLD with AlN target. The AlN films were deposited at a fixed temperature of $650^{\circ}C$, while conditions of nitrogen ($N_2$) pressure were varied between 0.1 mTorr and 10 mTorr. The quality of the AlN films was found to depend strongly on the $N_2$ partial pressure that was exerted during deposition. The X-ray diffraction studies revealed that the integrated intensity of the AlN (002) peak increases as a function the corresponding Full width at half maximum (FWHM) values decreases with lowering of the nitrogen partial pressure. We found that highly c-axis orientated AlN films can be deposited at a substrate temperature of $650^{\circ}C$ and a base pressure of $2{\times}10^{-7}Torr$ in the $N_2$ partial pressure of 0.1 mTorr. Also, it is noted that as the $N_2$ partial pressure decreased, the thermal conductivity increased.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.56.2-56.2
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• 2015

Nonthermal Atmospheric Pressure Plasmas and their Applications to Plasma Bioscience and Medicines have been introduced for next generation human healthcare's quantum developments. Various kinds of nonthermal atmospheric pressure plasmas have been introduced and their electron temperature and plasma densities along with reactive oxygen and nitrogen species have been diagnosed and analyzed for biological cell interactions, especially, used in Plasma Bioscience Research Center (PBRC), Korea. Herein, we have also introduced the plasma-initiated ultraviolet photolysis, which might be a generation mechanism for the reactive oxygen and nitrogen species (RONS) intracellular and extracellular regions inside the liquid when the plasma has been bombarded onto the water. Finally we have investigated the interactions of these RONS with the various cancer cells resulting in apoptotic cell death.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1993.10a
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• pp.58-62
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• 1993

This paper shows the discharge characteristics of liquid nitrogen under plane to plane electrode, needle to plance electrode, inserting teflon insulator in plane to plane electrode at atmospheric pressure. The main experimental device of this paper is cryostat. The important results obtained from this study are sa follows. Breakdown voltage of LN2 under N-P electrode is higher than that of under P-P electrode at atmospheric pressure. Breakdown duration time is longer with increase of electode gap under the P-P, N-P electrodes. The formation of bubbles by evaporation is observed in spite of non-applying source at atmospheric pressure and the creation of corona confirmed. Breakdown voltage and breakdown duration time are in proportion to increase of diameter in case of inserting teflon insulator. Partial discharge characteristics of thickness 0.5[mm] is that 채굼 voltage of teflon insulator rose with increase of diameter in each [pps].

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.1
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• pp.81-86
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• 2006

High temperature superconducting (HTS) power cable requires forced sub-cooled LN2 flow cooling. Liquid nitrogen is circulated by a pump and cooled back by cooling system. Typical operating temperature range is expected to be between 65 K and 77 K. The HTS power cable needs sufficient cooling to overcome its low temperature heat load. For successful cooling, the hydraulic characteristics of the HTS power cable must be well investigated to design the cables. Especially, the pressure drop in the cable is an important design parameter, because the pressure drop decides the length of the cable, size of the coolant circulation pump and circulation pressure, etc. This paper describes measurement and investigation of the pressure drop of the cooling system. In order to reduce the total pressure drop of the cooling system, the flow rate of liquid nitrogen must be controlled by rotational speed of the circulation pump.