• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.615-618
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• 2003

This paper presents Bi thin films have been fabricated by atomic layer-by-layer deposition and co-deposition at an IBS method. The growth rates of the films was set in the region from 0.17 to 0.27 nm/min. MgO(l00) was used as a substrate. In order to appreciate stable existing region of Bi 2212 phase with temperature and ozone pressure, the substrate temperature was varied between 655 and 820 $^{\circ}C$ and the highly condensed ozone gas pressure(PO$_3$) in vacuum chamber was varied between 2.0$\times$10$^{-6}$ and 2.3$\times$10$^{-5}$ Torr. Bi 2212 phase appeared in the temperature range of 750 and 795$^{\circ}C$ and single phase of Bi 2201 existed in the lower region than 785 $^{\circ}C$. Whereas, PO$_3$ dependance on structural formation was scarcely observed regardless of the pressure variation. And high quality of c-axis oriented Bi 2212 thin film with T$_{c}$(onset) of about 90 K and T$_{c}$(zero) of about 45 K is obtained. Only a small amount of CuO in some films was observed as impurity, and no impurity phase such as CaCuO$_2$ was observed in all of the obtained films.lms.

• Journal of Powder Materials
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• v.18 no.2
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• pp.141-148
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• 2011

Carbon material shows relatively high strength at high temperature in vacuum atmosphere and can be easily removed as CO or $CO_2$ gas in oxidation atmosphere. Using these characteristics, we have investigated the applicability of carbon mold for precision casting of high melting point metal such as nickel. Disc shape carbon mold with cylindrical pores was prepared and Ni-base super alloy (CM247LC) was used as casting material. The effects of electroless Nickel plating on wettability and cast parameters such as temperature and pressure on castability were investigated. Furthermore, the proper condition for removal of carbon mold by evaporation in oxidation atmosphere was also examined. The SEM observation of the interface between carbon mold and casting materials (CM247LC), which was infiltrated at temperature up to $1600^{\circ}C$, revealed that there was no particular product at the interface. Carbon mold was effectively eliminated by exposure in oxygen rich atmosphere at $705^{\circ}C$ for 3 hours and oxidation of casting materials was restrained during raising and lowering the temperature by using inert gas. It means that the carbon can be applicable to precision casting as mold material.

• Journal of Powder Materials
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• v.18 no.3
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• pp.262-268
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• 2011

In order to investigate the microstructure and mechanical properties of WC-10 wt% Co insert tool alloy fabricated by PIM (Powder Injection Molding) process, the feedstock of WC-10 wt% and wax used as a kind of binder were mixed together by two blade mixer. After injection molding, the debinding process was carried out by two-steps. First, solvent extraction, in which the binder was eliminated by putting the specimen into normal hexane for 24 hrs at $60^{\circ}C$, and subsequently thermal debinding which was conducted at $260^{\circ}C$ and $480^{\circ}C$ for 6 hrs in the mixed gas of $H_2/N_2$, respectively. Meantime, in order to compensate the decarburization due to hydrogen, 1.2~1.8% of carbon was added to ensure the integrity of the phase. Finally, the specimens were sintered in vacuum under different temperatures, and the relative density of 99.8% and hardness of 2100 Hv can be achieved when sintered at $1380^{\circ}C$, even the TRS is lower than the conventional sintering process.

• Journal of Plant Biotechnology
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• v.34 no.4
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• pp.293-298
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• 2007

Robinia pseudoacacia var. umbraculifera, commonly called umbrella black locust were regenerated after co-cultivation of internode segments with Agrobacterium tumefaciens which included yeast cadmium factor 1 (YCF 1) gene. The tolerance to cadmium and lead for plants can be increased by the YCF1 gene expression. Moreover, the recent studies have shown that YCF1 gene transgenic plants increase the accumulation of cadmium and lead into plant vacuoles. The effect of plant growth regulator such as 2,4-dichlorophenoxyacetic acid (2,4-D), ${\alpha}$-naphthaleneacetic acid (NAA), 6-benzyladenine (BA), and thidiazuron (TDZ) were studied to evaluate the propagation of plants through internode explants. The efficient induction of multiple adventitious shoots and callus were observed on a medium supplemented with 0.1 mg/L TDZ + 0.2 mg/L BA. To induce shoot elongation and rooting, regenerated shoots were transferred into basal MS medium without any plant growth regulator. Successful Agrobacterium tumefaciens mediated transformation was obtained by 20 min vacuum-infiltration with $50{\mu}M$ acetosyringone on the optimal multiple shoot induction medium with 30 mg/L hygromycin and 300 mg/L cefotaxime. To confirm the integration and expression of transgene, Polymerase Chain Reaction (PCR) and Reverse Transcriptase PCR (RT-PCR) were performed with specific primers. The frequency of transformation was approximately 18.94%. This study can be used to genetic engineering of phytoremediator.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.6
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• pp.690-696
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• 2010

Abatement of perfluorocompounds (PFCs) used in semiconductor and display industries has received an attention due to the increasingly stricter regulation on their emission. In order to meet this circumstance, we have developed a radio frequency (RF) driven plasma reactor with multiple annular shaped electrodes, characterized by an easy installment between a processing chamber and a vacuum pump. Abatement experiment has been performed with respect to $CF_4$, a representative PFCs widely used in the plasma etching process, by varying the power, $CF_4$ and $O_2$ flow rates, $CF_4$ concentration, and pressure. The influence of these variables on the $CF_4$ abatement was analyzed and discussed in terms of the destruction & removal efficiency (DRE), measured with a Fourier transform infrared (FTIR) spectrometer. The results revealed that DRE was enhanced with the increase in the discharge power and pressure, but dropped with the $CF_4$ flow rate and concentration. The addition of small quantity of $O_2$ lead to the improvement of DRE, which, however, leveled off and then decreased with $O_2$ flow rate.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.433-433
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• 2012

As the requirement in patterning geometry continuously shrinks down, the termination of etch process at the exact time became crucial for the success in nano patterning technology. By virtue of real-time optical emission spectroscopy (OES), etch end point detection (EPD) technique continuously develops; however, it also faced with difficulty in low open ratio etching, typically in self aligned contact (SAC) and one cylinder contact (OCS), because of very small amount of optical emission from by-product gas species in the bulk plasma glow discharge. In developing etching process, one may observe that coupon test is being performed. It consumes costs and time for preparing the patterned sample wafers every test in priority, so the coupon wafer test instead of the whole patterned wafer is beneficial for testing and developing etch process condition. We also can observe that etch open area is varied with the number of coupons on a dummy wafer. However, this can be a misleading in OES study. If the coupon wafer test are monitored using OES, we can conjecture the endpoint by experienced method, but considering by data, the materials for residual area by being etched open area are needed to consider. In this research, we compare and analysis the OES data for coupon wafer test results for monitoring about the conditions that the areas except the patterns on the coupon wafers for real-time process monitoring. In this research, we compared two cases, first one is etching the coupon wafers attached on the carrier wafer that is covered by the photoresist, and other case is etching the coupon wafers on the chuck. For comparing the emission intensity, we chose the four chemical species (SiF2, N2, CO, CN), and for comparing the etched profile, measured by scanning electron microscope (SEM). In addition, we adopted the Dynamic Time Warping (DTW) algorithm for analyzing the chose OES data patterns, and analysis the covariance and coefficient for statistical method. After the result, coupon wafers are over-etched for without carrier wafer groups, while with carrier wafer groups are under-etched. And the CN emission intensity has significant difference compare with OES raw data. Based on these results, it necessary to reasonable analysis of the OES data to adopt the pre-data processing and algorithms, and the result will influence the reliability for relation of coupon wafer test and whole wafer test.

• Journal of the Korean Applied Science and Technology
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• v.2 no.1
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• pp.19-23
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• 1985

In order to know the quality changes of the fat and oil foods packed in plastics film by the sunlight, we examined the sunlight transmitting rate by the kind of films and measured the acid value and peroxide value according to it. The results obtained were as follows : 1. The sunlight transmitting rate of various films was explained especial permeability under the wavelength of less than 300nm, but it marked a regular form under that of more than 30nm. 2. The vacuum evaporation film with aluminum on the polyester shuts off most of the sunlight, therefore, it has the best effect that keeps the fats and oils off rancidity. 3. The sunlight transmitting rate of the white color printing film drops about 80% as compared with not printing. 4. The preventive power against the rancidity of fats and oils is PET/Al, PET, PE, nylon and OPP film in that order. The changes of peroxide value and acid value were approximately the same as that of the sunlight transmitting rate.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.2
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• pp.150-157
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• 2004

Carbon dioxide ($CO_2$, R-744) has become a very popular issue in application to refrigeration and air conditioning systems as a natural refrigerant. An experimental study has been carried out to investigate miscibility and the vapor pressure of refrigerant R-744 in the presence of lubricant oil. This is of particular interest in the selection of the lubricant oil for the compressor of a refrigeration system or an air conditioning system using the refrigerant R-744. The experimental set-up consists of the equilibrium cell, measuring devices, the vacuum pump, the constant temperature bath and relevant connecting pipes made of stainless steel. Five lubricant oils, such as mineral oil (Naphthenic), AB (Alkyl Benzene) oil, PAO (Poly Alpha Olefin) oil, PAG (Poly Alkylene Glycol) oil and POE (Polyol Ester) oil are considered in the present study. Test runs were conducted with the oil concentration range from 5 to 50 wt％, and the temperature range from -10 to 1$0^{\circ}C$ with 2$^{\circ}C$ intervals. The miscibility results are visualized and correlated with the vapor pressure for the individual test components.

• Applied Science and Convergence Technology
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• v.23 no.5
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• pp.279-283
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• 2014

Al doped ZnO thin films have been deposited by a RF magnetron sputtering technique from a ZnO (2 wt.% $Al_2O_3$) target onto glass substrates heated at temperature ranging from RT to $400^{\circ}C$. X-ray diffraction analysis shows that the deposits have a preferential growth along the c-axis of a hexagonal structure. The full with at half maximum decreases from 0.45 to $0.43^{\circ}$ in the studied temperature range. The root main square surface roughness increases with substrate temperature from 1.89 to 2.67 nm. All films are transparent up to 80% in the visible wavelength range and the adsorption edge is red-shifted with substrate temperature from RT to $400^{\circ}C$. The sheet resistance increases from 92 ohm/sq to 419 ohm/sq when the deposition temperature increases from RT to $400^{\circ}C$. The increment of sheet resistance is caused by lowered carrier concentration resulting from an increase in surface roughness.

• Food Science of Animal Resources
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• v.33 no.1
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• pp.58-66
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• 2013

In this study, the effect of packaging methods [aerobic packaging (AP), vacuum packaging (VP) and modified atmosphere packaging (MAP: 75% $N_2$, 25% $CO_2$)] on colour, lipid quality and microbial growth of beef patties enhanced with flaxseed flour was investigated during storage at $2{\pm}1^{\circ}C$ for 10 d. L and a values of beef patties packaged in MAP and VP were higher (p<0.05) than that of the samples packaged in AP. Packaging in MAP and VP retarded the lipid oxidation (TBA value) and inhibited the bacterial growth of beef patties enhanced with flaxseed flour. Furthermore, TBA values in beef patties were correlated with a values (r = -0.340; p<0.05). Packaging in MAP was more effective than packaging in VP for inhibiting microbial growth. The samples packaged in VP lost their shape due to the compression by external atmosphere. Packaging treatment had no significant effect on saturated fatty acid (SFA), monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA) levels in beef patties. The a and b, TBA and MUFA values changed during storage time. TBA values for beef patties increased during storage time, but did not reach to the limit value (1 mg/kg) until the end of the storage time. The results suggest that the shelf life of beef patties enhanced with flaxseed flour can be extended by packaging in MAP.