• Korean Journal of Materials Research
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• v.13 no.1
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• pp.36-42
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• 2003

The oxidation behaviors of Y-Cr bilayer deposited on ferritic steel by magnetron-sputtering for application of the Fe-Cr alloys as interconnectors of planar-type solid oxide fuel cells (SOFCs) were studied. After oxidation at $800^{\circ}C$ for 40 hours, the major phase of $Y_2$$O_3$and the minor phase of $YCrO_3$, $Mn_{1.5}$ $Cr_{1.5}$ $O_4$and Cr$_2$SiO$_4$were formed in the Y/Cr bilayered samples, while the major phase of Cr$_2$O$_3$and the minor phase of $Y_2$$O_3$were formed as the major phase in the Cr/Y bilayered samples. The Log(ASR/T) that expresses electric resistance of the Y/Cr coated specimen with nonconducting $_Y2$$O_3$oxide showed high value of -2.80 Ω$\textrm{cm}^2$$K^{-1}$ / and that of the Cr/Y coated specimen with conducting $Cr_2$$O_3$oxide appeared to be -4.11 Ω$\textrm{cm}^2$$^{K}$ . The electric resistance of the Y/Cr coated specimen was largely increased due to the formation of high resistance oxide scales. However, the Cr/Y coated specimen did not show any increase in the electric resistance and had the long-term stability of oxidation because there was no formation of the secondary phases with low conductivity.

• Resources Recycling
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• v.12 no.6
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• pp.19-25
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• 2003

This experiment was carried out to examine the effect of iron oxide roasting for Sr-ferrite magnet. Chloride content was decreased with raising the 2 nd roasting temperature of iron oxide for ruthner process iron oxide. The optimization temperature for roasting of ruthner process iron oxide was around $800^{\circ}C$ as average particle size 1.5∼1.9 $\mu\textrm{m}$, apparent bulk density 1.4 g/$m\ell$ and chloride content 0.05%. The relation between Br and HcJ by sintering temperature for Sr-ferrite magnet was found to be Br≒-0.258HcJ＋494. In case of having a vibrating disk mill for the ruthner process iron oxide, the magnetic properties were Br 421 mT and HcJ 251 kA/m.

• Food Science of Animal Resources
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• v.29 no.2
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• pp.245-251
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• 2009

This study was carried out to investigate the fatty acid composition, aroma pattern, color, and oxidative stability of M. longissimus from 28-mon-old Hanwoo steers with different raising altitude (100, 200, 300, 400, 700, and 800 m above sea level). The samples were stored at $2{\pm}0.2^{\circ}C$ for 9 d. Meat from 700 and 800m had lower palmitic acid, saturated fatty acids and higher oleic acid, monounsaturated fatty acids (MUFA) than that from 100 m (p<0.05). There was no positive discrimination of the aroma pattern of meat among all groups. There were no significant difference in TBARS values of beef among all groups at 6 and 9 d of storage. At 9d of storage, meat from 700m showed the highest MetMb concentration and the lowest a* value among all groups. However, the differences in Mb concentration and color among groups were not linear to the difference in raising altitude. Consequently, the difference in raising altitude at 100-800 m affected the fatty acid composition of meat from Hanwoo steers; the higher the raising altitude, the higher the MUFA concentration. The difference in fatty acid composition among them didn't affect the aroma pattern and oxidative stability.

• Journal of the Korean institute of surface engineering
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• v.39 no.5
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• pp.240-244
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• 2006

Tribaloy 800 (T800) powder is coated on the Inconel 718 substrate by the optimal High Velocity Oxy-Fuel (HVOF) thermal spray coating process developed by this laboratory. For the study of the possibility of replacing of the widely used classical chrome plating, friction, wear properties and sliding wear mechanism of coatings are investigated using reciprocating sliding tester both at room and at an elevated temperature of $1000^{\circ}F\;(538^{\circ}C). Both at room temperature and at $538^{\circ}C$, friction coefficients and wear debris of coatings are drastically reduced compared to those of non-coated surface of Inconel 718 substrate. Friction coefficients and wear traces of both coated and non-coated surfaces are drastically reduced at higher temperature of $538^{\circ}C$ compared with those at room temperature. At high temperature, the brittle oxides such as $CoO,\;Co_3O_4,\;MoO_2,\;MoO_3$ are formed rapidly on the sliding surfaces, and the brittle oxide phases are easily attrited by reciprocating slides at high temperature through complicated mixed wear mechanisms. The sliding surfaces are worn by the mixed mechanisms such as oxidative wear, abrasion, slurry erosion. The brittle oxide particles and melts and partial-melts play roles as solid and liquid lubricant reducing friction coefficient and wear. These show that the coating is highly recommendable for the durability improvement coating on the surfaces vulnerable to frictional heat and wear.

• Korean Journal of Digital Imaging in Medicine
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• v.14 no.1
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• pp.21-29
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• 2012

The purpose of this study is to evaluate the mutual relations by measuring SNR from T2 weighted image and ADC values on the basis of the stiffness values from liver tissues. This study was conducted that total 37 people(23 of males and 11 of females) were taken the liver MRI examination and average age was $54.5{\pm}12.7$ years old. The equipment was MAGNETOM Skyra 3.0T (SIEMENS, Erlangen, Germany) and 32 channel body-array coil. The examination were conducted with HASTE T2 weighted image by axial plane, Spin-echo EPI (echo planner image) DWI (b-value = 800) and Magnetic resonance elastography. The ROIs (region of interest: 200-300 $mm^2$) were established on the basis of the first axial stiffness image corresponded 95% confidence interval from axial stiffness image and then were measured values. After drawing the grid lines, signals were measured SNR from T2 weighted image and ADC values on the same locations that were analysed other 3 planes respectively. The results were showed correlation (0.057) that were increased to SNR from T2 weighted image by increasing stiffness value that no significant difference statistically p = 0.003. Other results were showed correlations (-0.301) that were decreased to ADC values by increasing stiffness values that no significant difference statistically p = 0.088. In the 3.0T equipment, the results may be error in much the same fashion as the 1.5T from ADC values by evaluation of fibrosis stage. However, Magnetic resonance elastography would be useful method that is used to diagnose exactly liver fibrosis stages in the 3.0T.

• Journal of Energy Engineering
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• v.12 no.1
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• pp.29-34
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• 2003

Thermo-acoustic waves can be generated in a compressible fluid by rapid heating and cooling near the boundary walls. These phenomena are very important mechanism of heat transfer in the space environment in which natural convection does not exist. In this study, the generation and transmission characteristics of thermo-acoustic waves in an air filled enclosure with rapid wall heating are studied numerically. The governing equations were discretized using control volume method, and were solved using PISO algorithm and second-order upwind scheme. For the stable solution time step were considered as t=1$\times$$10^{-9}$ order, and grids are 50$\times$800. The induced thermo-acoustic wave propagates through the fluid until it decays due to viscous and heat dissipation. The wave showed sharp front shape and decreased with long tail.

• Journal of Korean Ophthalmic Optics Society
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• v.3 no.1
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• pp.15-19
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• 1998

The purpose of this study, when one prepared lead zirconate thin films by sol-gel method, was to find the preferred direction of crystal growth and dielectric characteristics for ratio of Pb and Zr. We used the Pt/Ti/$SiO_2$/Si substrate, and annealing condition was $800^{\circ}C$ for lminute. When Pb was deficient, preferred direction was <221>. And when it was stoichiometric ratio, they were grown <200> and <221> direction. But they have antiferroelectric properties, they don't appear distinct domain switching.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.9
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• pp.821-826
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• 2005

In this paper, in order to develop lead-free piezoelectric ceramics, $(Li_{0.04}Na_{0.44}K_{0.52)(Nb_{0.86}Ta_{0.10}Sb_{0.04})O_3$ ceramics were fabricated with the variation of calcination temperature and sintering temperature. The ceramics couldn't be sintered at temperature less than $1110^{\circ}C$ and showed the highest density at calcination temperature of $800^{\circ}C$. Crystal structure of the ceramics showed pseudo-tetragonal phase. At the calcination temperature of $800^{\circ}C$ and sintering temperature of $1110^{\circ}C$, the optimal values of $density=4.64g/cm^3,\;kp=0.45,\;{\varepsilon}r=1336,\;d_{33}=254pC/N\;and\;Tc=335^{\circ}C$ were obtained.

• Journal of Biosystems Engineering
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• v.19 no.4
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• pp.343-357
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• 1994

Current commercial dairy feed has various problems in low feed productivity, inadequate formulation and higher feeding cost due to excessive capital investment and non-specialized system for the end product. To solve those problems, 6 TMR terminal models were developed in this study. The developed TMR terminal system consists of TMR terminal, TMR main center and combined system linked TMR terminal and TMR main center. 15 TMR main center models were developed to support 10, 20, 30, 40, 50 TMR terminal(30 ton/day basis) by 3 different types, and evaluated for capital investment and operation cost by the analysis of the newly developed computer program. Optimum model size is analyzed and suggested for each model. Followings are summary of this study : 1. The capital investment costs of TMR main centers were 1,600 to 3,800 million won for type 1, 2,200 to 4,500 million won for type 2 and 2,200 to 4,800 million won for type 3. Also model MACE30 or bigger were justified as the economical models. 2. The feed production costs of TMR main center models were 3,166 to 4,824 won/ton for type 1, 3,816 to 6,182 won/ton for type 2 and 3,990 to 6,263 won/ton for type 3. So feed production cost range was 3,166 to 6,263 won/ton. 3. The bigger production capacity, the less TMR main center production cost. The feed production cost of the biggest model MACE50 was 62~65% of smallest model MACE10.

• Journal of the Korean Society of Clothing and Textiles
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• v.32 no.5
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• pp.800-807
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• 2008

The purpose of this study is to compare the subjective texture of actual objects and their picture images on the Internet to find out a method to present visual images in order to supply information similar real objects. For this study, seven knit fabrics and four presentation methods of visual images including twice magnifications and two dimensions of 2D and 3D. The results of this study were as follows: There are significant differences among subjective textures evaluated by touching seven fabrics actually and we can verify the effects of fiber contents and loop length of knit on textures. We can find out differences of texture depending on presentation methods. In case of 2D evaluation of knits fabrics, visual images of real size present a little exact information on roughness and heaviness whereas those of twice magnification do roughness, wetness, softness and luster. And 3D images give us more exact information of textures on softness, heaviness and warmness, but rather twice enlarged 3D image can't supply an information of heaviness texture.