• Asian-Australasian Journal of Animal Sciences
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• 제29권5호
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• pp.659-665
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• 2016

The effects of three different feeding systems on beef cattle production performance, rumen fermentation, and rumen digesta particle structure were investigated by using 18 Limousin (steers) with a similar body weight ($575{\pm}10kg$) in a 80-d experiment. The animals were equally and randomly divided into three treatment groups, namely, total mixed ration group (cattle fed TMR), SI1 group (cattle fed concentrate firstly then roughage), and SI2 group (cattle fed roughage firstly then concentrate). The results showed that the average daily gain was significantly higher in cattle receiving TMR than in those receiving SI1 and SI2 (p<0.05). Consumption per kg weight gain of concentrate, silage, and combined net energy (NEmf) were significantly decreased when cattle received TMR, unlike when they received SI1 and SI2 (p<0.05), indicating that the feed efficiency of TMR was the highest. Blood urea nitrogen (BUN) was significantly decreased when cattle received TMR compared with that in cattle receiving SI1 (p<0.05), whereas there was no difference compared with that in cattle receiving SI2. Ammonia nitrogen concentration was significantly lower in cattle receiving TMR than in those receiving SI1 and SI2 (p<0.05). The rumen area of cattle that received TMR was significantly larger than that of cattle receiving SI1 (p<0.05), but there was no difference compared with that of cattle receiving SI2. Although there was no significant difference among the three feeding systems in rumen digesta particle distribution, the TMR group trended to have fewer large- and medium-sized particles and more small-sized particles than those in the SI1 and SI2 groups. In conclusion, cattle with dietary TMR showed increased weight gain and ruminal development and decreased BUN. This indicated that TMR feeding was more conducive toward improving the production performance and rumen fermentation of beef cattle.

• 한국재료학회지
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• 제12권8호
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• pp.650-655
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• 2002

$SiO_2$ gels containing dispersed fine Te metal particles have been prepared by the sol- gel method using a starting solution containing Tetraethoxy Silane (Si($OC_2$ $H_{5}$ )$_4$), $H_2$O, Ethylalchol ($C_2$$H_{5}$OH), Nitric Acid ($HNO_3$) and Tellurium Tetracholoride ($TeCl_4$) in a several molar ratio. Gelling time of sols was about 3 days and viscosity of solution was very low about 2~3 cP for 3 days. Heat-treatments of the gel have been performed at 500, 700, 900, 1100 and $1300^{\circ}C$ for 1 hour, respectively. We have investigated TG-DTA, X-ray diffraction patterns and SEM of heat-treatmented gels. The size of Te fine particles dispersed in $SiO_2$ gel was about 0.8~1 $\mu\textrm{m}$ and the shape was almost quadrangle.

• 반도체디스플레이기술학회지
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• 제10권2호
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• pp.73-81
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• 2011

We manufactured the inkjet printing system for the application into the nano Ag finger line interconnection process in Si solar cells. The home-made inkjet printer consists of motion part for XY motion stage with optical table, head part, power and control part in the rack box with pump, and ink supply part for the connection of pump-tube-sub ink tanknozzle. The ink jet printing system has been used to conduct the interconnection process of finger lines on Si solar cell. The nano ink includes the 50 nm-diameter. Ag nano particles and the viscosity is 14.4 cP at $22^{\circ}C$. After processing of inkjet printing on the finger lines of Si solar cell, the nano particles were measured by scanning electron microscope. After the heat treatment at $850^{\circ}C$, the finger lines showed the smooth surface morphology without micropores.

• Journal of Pharmaceutical Investigation
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• 제37권4호
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• pp.217-222
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• 2007

To develop cleansing tissue composed of silicone multiple emulsions which could easily remove make-up residues and confer skin protecting effect without damaging skin, we formulated various silicone multiple emulsions and evaluated the physicochemical properties including viscosity, cleansing effect, and safety effect. Also, cleansing tissue incorporated with silicone multiple (W/Si/W) emulsion was stored for 6 months, and judged its stability through microscopes under accelerated and long-term condition. Cleansing effect was evaluated by chromameter. Skin hydration effect was determined by corneometer and incorporation effect into non-woven fabric cotton was evaluated by volunteer survey. Low viscosity ranged from 400 centipoise (cP) to 1,000 cP was obtained from a stabilized W/Si/W emulsion containing more than 10% volatile silicone. Mean diameter of fresh W/Si/W emulsion was $20{\mu}m$, but after storage for 3 months at $45^{\circ}C$, the particle size of the W/Si/W emulsion increased up to $50{\mu}m$. Both W/Si/W emulsion-incorporated cleansing tissue and commercial product showed equally good cleansing effect. In addition, skin allergies such as erythema, edema, scaling itching, stinging, burning, tightness and prickling were not observed through macroscopic examination. From the transepidermal water loss results, the cleansing tissue consisting of W/Si/W emulsion showed superior hydration effect to commercial product. In conclusion, this study suggests cleansing tissue using W/Si/W emulsion could be used for an excellent efficacy compared with commercialized cleansing tissue.

• Composites Research
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• 제22권5호
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• pp.15-23
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• 2009

가압주조법으로 제조한 $Al_2O_3$ 섬유와 SiC 입자 혼합 보강 금속복합재료(MMCs)의 상온과 고온에서 윤활마모특성을 조사하였다. 마모시험은 거리와 온도의 변화에 따라 속도를 고정시켜 25Kgf의 하중하에서 수행하였으며 MMCs의 시험편은 가압의 수평(PR)방향과 수직(N)방향에서 채취하였다. 혼합비의 영향을 관찰한 결과 상온에서는 20%섬유만 보강한 PR방향 MMCs의 마모거동은 N방향 보다 우수한 결과를 보였으나, 혼합보강 MMCs는 반대로 나타내었다. 고온($100^{\circ}C$)에는 모든 MMCs에서 PR방향의 마모거동이 N 방향보다 우수한 결과를 보인 것은 보강재와 마찰면간 윤활필름이 강호작용에 기인한 것으로 밝혀졌다. $150^{\circ}C$에서는 혼합 MMCs의 마모거동은 온도영향으로 PR이 N 보다 우수한 결과를 보였다.

• 한국세라믹학회지
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• 제52권6호
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• pp.455-461
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• 2015

Porous ceramics with tailored pore size and shape are promising materials for the realization of a number of functional and structural properties. A novel method has been reported for the investigation of the role of SiC in the formation of $SiO_2$ foams by colloidal wet processing. Within a suitable pH range of 9.9 ~ 10.5 $SiO_2$, particles were partially hydrophobized using hexylamine as an amphiphile. Different mole ratios of the SiC solution were added to the surface modified $SiO_2$ suspension. The contact angle was found to be around $73^{\circ}$, with an adsorption free energy $6.8{\times}10^{-12}J$. The Laplace pressure of about 1.25 ~ 1.6 mPa was found to correspond to a wet foam stability of about 80 ~ 85%. The mechanical and thermal properties were analyzed for the sintered ceramics, with the highest compressive load observed at the mole ratio of 1:1.75. Hertzian indentations are used to evaluate the damage behavior under constrained loading conditions of $SiO_2$-SiC porous ceramics.

• 한국세라믹학회지
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• 제42권5호
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• pp.333-337
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• 2005

In order to improve the performance of green emitting phosphors for plasma display panel, the $Zn_2SiO_4:Mn,Al$ phosphors were synthesized using sol-gel technique and studied using SEM and VUV photoluminescence spectrometer. pH values of the starting solutions (pH = 0.5$\~$2.34) were controled by HCl as the catalysis of hydrolysis and wet gels were dried at $80^{\circ}C$ and $120^{\circ}C$, respectively. We investigated the effects of pH and drying temperatures during sol-gel processes. The results indicated that the phosphor prepared at pH = 1 showed the maximum emission intensity in both drying conditions and the effect of pH of the starting solution on morphology were increased with particle size as HCl and phosphor dried at high temperature showed more spherical and smaller particles than at low.

• 한국정밀공학회지
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• 제17권6호
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• pp.199-209
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• 2000

Particles reinforced MMCs have higher specific modulus, higher specific strength, better properties at elevated temperatures and better wear resistance than monolithic metals. But the coefficient of thermal expansion(CTE) of Al6061 is 5 times larger than that of SiCp. The discrepancy of CTE makes some residual stresses inside of MMCs. This work investigates Si$C_p$/Al6061 composites at high temperatures in the microscopic view by three-dimensional elasto-plastic finite element analyses and compares the analytical results with the experimental ones. The theoretical model is not able to consider the nonuniform shape of particle. So the shape of particle is assumed to be perfect global shape. And also particle distribution is not homogeneous in experimental specimen. It is assumed to be homogeneous in simulation model. The type of particle distribution is face-centered cubic array(FCC array). Furthermore, non-homogeneous distribution is modeled by combination of several volume fractions.

• Transactions on Electrical and Electronic Materials
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• 제4권2호
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• pp.20-23
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• 2003

Piezoelectric powder with the composition of PbTiO$_3$-PbZrO$_3$-Pb(Mn$\_$1/3/Nb$\_$2/3/)O$_3$ and small particle size of 0.3 $\mu\textrm{m}$ was investigated for low-temperature firing of PZT thick films. PbTiO$_3$-PbZrO$_3$-Pb(Mn$\_$1/3/Nb$\_$2/3)O$_3$ ceramics showed dense microstructure and superior piezoelectric properties, electromechanical coupling factor (k$\_$p/) of 0.501 and piezoelectric constant (d$\_$33/) of 224. The PZT paste was made of the powder and organic vehicles, and screen-printed on Pt(450nm)/YSZ(110nm)/SiO$_2$(300nm)/Si substrates and fired at 800∼900$^{\circ}C$. Any interface reaction between the PZT thick film and the bottom electrode was not observed in the PZT thick films. The PZT thick film fired at 800$^{\circ}C$ showed moderate electrical properties, the remanent polarization(p$\_$r/) of 16.0 ${\mu}$C/$\textrm{cm}^2$, the coercive field(E$\_$c/) of 36.7 ㎸/cm, and dielectric constant ($\varepsilon$$\_$r/) of 531. Low-temperature sinterable piezoelectric composition and high activity of fine particles reduced the sintering temperature of the thick film. This PZT thick film could be utilized for piezoelectric microactuators or microsensors that require Si micromachining technology.

• The Korean Journal of Ceramics
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• 제3권2호
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• pp.116-123
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• 1997

A chemically stabilized $\beta$-cristobalite, which is stabilized by stuffing cations of $Ca^{2+}$ and $Al^{3+}$, was prepared by a solution-polymerization route employing Pechini resin or PVA solution as a polymeric carrier. The polymeric carrier affected the crystallization temperature, morphology of calicined powder, and particle size distribution. In case of the polyvinyl alcohol (PVA) solution process, a fine $\beta$-cristobalite powder with a narrow particle size distribution (average particle size : 0.3$\mu\textrm{m}$) and a BET specific surface area of 72 $\m^2$/g was prepared by an attrition-milling for 1 h after calcination at 110$0^{\circ}C$ for 1h. Wider particle size distribution and higher specific surface area were observed for the $\beta$-cristobalite powder derived from Pechini resin. The cubie(P1-to-tetraganalb) phase transformation in polynystalline $\beta$-cristobalite was induced at approximately 18$0^{\circ}C$. Like other materials showing transformation toughening, a critical size effect controlled the $\beta$-to-$\alpha$ transformation. Densifed cristobalite sample had some cracks in its internal texture after annealing. The cracks, occurred spontaneoulsy on cooling, were observed in the sample with an average grain sizes of 4.0 $\mu\textrm{m}$ or above. In case of the sintered cristobalite having a composition of CaO.$2Al_2O_3$.40SiO$_2$, small amount of amorphous phase and slow grain growth during annealing were observed. Shear stress-induced transformation was also observed in ground specimen. Cristobalite having a composition of CaO.2Al2O3.80SiO2 showed a more sensitive response to shear stress than the CaO.$2Al_2O_3$.40SiO$_2$ type cristobalite. Shear-induced transformation resulted in an increase of volume about 13% in $\alpha$-cristobalite phase on annealing for above 10 h in the case of the former composition.