• Journal of Surface Science and Engineering
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• v.19 no.3
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• pp.83-91
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• 1986

Codeposited of boron nitride(BN) particle dispersed into electroless nickel-phosphours (Ni-P) and nickel-boron(Ni-B) platings were studied for the purpose of developing the wear resistance and lubricity. BN can be codeposited from electroless nickel plating bath with $NaH_2PO_2$ and $NaBH_4$ as the reducing agents. Most dispersolids were distributed uniformly in the Ni-P and Ni-B matrix. Abrasion loss decreased with increasing amount of codeposits and reached a constant value 2.4 percent by volume percent of BN particle. The wear resistance and the friction coefficient of the heat treated BN composite coatings were improved about three times than that of as-coatings. The BN composite coatings were more wear resistance than hard chromium. Ni-B-BN composite coatings showed lower wear resistance and friction coefficient than Ni-P-BN. The BN content of the deposite was found to be 2.4 v/o for these optium conditions.

• Korean Journal of Materials Research
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• v.29 no.9
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• pp.547-552
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• 2019

In the present study, the thermal conductivity of a silicon nitride($Si_3N_4$) thin-film is evaluated using the dual-wavelength pump-probe technique. A 100-nm thick $Si_3N_4$ film is deposited on a silicon (100) wafer using the radio frequency plasma enhanced chemical vapor deposition technique and film structural characteristics are observed using the X-ray reflectivity technique. The film's thermal conductivity is measured using a pump-probe setup powered by a femtosecond laser system of which pump-beam wavelength is frequency-doubled using a beta barium borate crystal. A multilayer transient heat conduction equation is numerically solved to quantify the film property. A finite difference method based on the Crank-Nicolson scheme is employed for the computation so that the experimental data can be curve-fitted. Results show that the thermal conductivity value of the film is lower than that of its bulk status by an order of magnitude. This investigation offers an effective way to evaluate thermophysical properties of nanoscale ceramic and dielectric materials with high temporal and spatial resolutions.

• Korean Journal of Metals and Materials
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• v.48 no.4
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• pp.353-356
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• 2010

InSb thin films with a thickness of approximately 300 nm were prepared using single- and double-source vacuum evaporation methods and their structures and properties were investigated in terms of a heat treatment procedure. The double-source InSb films, prepared by the alternate stacking of In and Sb, were polycrystalline in structure and included small amounts of unreacted In and Sb phases. After annealing at elevated temperatures below the melting point of InSb (525$^{\circ}C$), the films changed into the InSb phase and were found to contain small amounts of unreacted In. The formation capability of the InSb compound was slightly lower for multilayer films than for single-layer films. The electrical and galvanomagnetic properties were found to be strongly related to the microstructures of the films. The maximum value of the Hall mobility and the magnetoresistance were determined to be $4.3{\times}10^3cm^2$/Vs and 70%, respectively, for the single-layer films, while these values for the alternately stacked films were respectively $2.9{\times}10^3cm^2$/Vs and 29% for the $[Sb(2.5)/In(2.5)]_{60}$ films, and $3.1{\times}10^3cm^2$/Vs and 10% for the $[Sb(150)/In(150)]_1$ films.

• Journal of Hydrogen and New Energy
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• v.32 no.6
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• pp.636-641
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• 2021

Using numerical analysis, various factors influencing the performance development of high-pressure pumps for Dimethyl Ether (DME) engines were identified and the impact of each factor was evaluated using Taguchi method. DME fuels are more compressive than diesel fuels and have the lower heat generation, so it is necessary to increase the size of the plunger and speed (RPM) of the pump as well. In addition, it is necessary to change the shape and design of control valve to control the discharge flow and pressure. In this study, various variables affecting the performance and flow rate increase of high-pressure pumps for DME engines are planned using Taguchi method, and the best design method is proposed using correlation of the most important variables. As a result, we were able to provide the design value needed for a six-liter engine and provide optimal conditions. The best combination factors to optimize the flow rate at RPM 2,000 and diameter plunger with 20 mm. The regression equation can also be used to optimize the flow rate; -8, 13+0, 2552 RPM +54, 17 diam. Plunger.

• Journal of Animal Science and Technology
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• v.52 no.5
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• pp.413-426
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• 2010

This study was conducted to investigate the effects on fermentation characteristics of rumen microorganism by different types and levels of lignosulfonate treated soybean meal (LSBM) in in vitro test and rumen simulation continuous culture (RSCC) system in dairy cows. The experiment I was control and 12 treatments (each with 3 replications) in vitro test to demonstrate composition of different types of treatments with lignosulfonate (Desulfonate, Na, Ca and solution) and levels (2, 4 and 8%) of soybean meal in the dairy cow diet. LSBM source treatments in the dairy cow diet showed pH value, $NH_3$-N concentration and total VFA concentration lower than control at all levels and incubation times (p<0.05). Dry matter digestibility of LSBM source treatments showed lower than control (p<0.05). Gas production and rumen microbial synthesis was decreased by rumen microbial fermentation for incubation times. Undegradable protein (UDP) concentration of all LSBM treatments was decreased for incubation times, and significantly higher than control (p<0.05). In the experiment II compared diets of the control, LSBM Na 2%, LSBM Sol 2%, which are high performance to undegradable protein (UDP) concentration experiment I in vitro test, and heated treatment lignosulfonate (LSBM Heat) 2% in the dairy cow diet from four station RSCC system ($4{\times}4$ Latin square). A rumen microbial fermentation characteristic was stability during 12~15 days of experimental period in all treatments. The pH value of LSBM treatments was higher than control treatment (p<0.05). The $NH_3$-N concentration, VFA concentration and rumen microbial synthesis of LSBM treatments were lower than control (p<0.05). The undegradable protein (UDP) showed LSBM Na 2% (45.28%), LSBM Sol 2% (43.52%) and LSBM Heat 2% (43.49%) higher than control (41.55%), respectively (p<0.05). Those experiments were designed to improve by-pass protein of diet and milk protein in the dairy cows. We will conduct those experiments the in vivo test by LSBM treatments in dairy cows diet.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.2
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• pp.96-99
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• 2000

The photoluminescened experiments at temperature of 10K were carride out for ZnSe epilayers grown by hot-wall epitaxy. The upper and lower polariton peaks of the neutral dound exciton $I_2$($D^{\circ}$,X) for as-grown epilayer have been dominantly observed.For the heat-treatment under Se ambient,the origin of $I_2$ emission is confirmed to be related to Se-vacancy.The extra neutral acceptor bound exciton $I_1$$^d$ is also observed.The ZnSe epilayer shows the self-compensation effect and it is hard to be converted into p-type ZnSe epilayer.However,the photoluminescence spectrum of the annealed sample in Se ambient shows the intense $I_1$$^d$ emission.This indicates that in the annealed ZnSe epilayer,there are many acceptor levels due to the opical p-type converstion. The binding energy of acceptor-impurity is ecaluated to the value of 268meV and the self-activated emission is disappeared by thermal annealing under Se ambient,which indicates the association with Se-vacancy.

• Asian-Australasian Journal of Animal Sciences
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• v.4 no.4
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• pp.395-398
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• 1991

Physiological reactions of 24 six months old (22.7 kg. body weight) Barki ram lambs, to hot summer conditions, as influenced by asbestos shading at Maryout area were studied. Animals (12 shaded and 12 Unshaded) developed hyperthermia during summer as their rectal temperature (RT) and respiration rate (RR) were always higher (p<0.01) than normal. Asbestos shading caused higher (p<0.05) RT and RR ($39.5^{\circ}C$ and 69.9 r.p.m. vs. 39.2 and 45.7 r.p.m.) of rams at morning (6-8 a.m.) which became lower ($39.9^{\circ}C$ and 104.3 r.p.m. vs. $40.1^{\circ}C$ and 120.5 r.p.m.) in afternoon (2-4 p.m.) as compared to sun exposure. Shading also resulted in higher hematocrit value (PCV) (35.3% vs. 33.0%) and lower (p<0.05) daily weight gain (128.57 vs. 131.43 g). Diurnal (p<0.01) and monthly (p<0.05) RT and RR changes were closely associated with air temperature (AT) fluctuations. Monthly variation (p<0.05) in PCV was evident. Puberty was reached one month later in the shaded as compared to the unshaded group (265 vs. 232.3 day, respectively). It is concluded that asbestos shading prevents efficient heat dissipation to the sky by hyperthermic rams during summer nights. Construction materials for animal shelters are of extreme practical importance.

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.553-556
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• 2009

This research aims at the recovery of valuable resource and more efficient waste treatment through solving the problem of pyrolysis technique. At first, in order to raise the economical efficiency, the low temperature pyrolysis experiment was carried out at the temperature of $450^{\circ}C$, which is lower than the common pyrolysis temperature area ($500{\sim}1000^{\circ}C$). We could lower the reaction temperature and reduce the reaction time by using catalyst. Also we used indirect heat for the purpose of maintaining favorable anoxic condition. As a result, we could raise the recovery rate of the valuable copper and synthetic fuel oil. Furthermore, the by-products and flue gas could be treated more effectively as well. The flue gas passed through two stage neutralization tank, so that dioxin hardly occurs and other environment items are controlled fairly well to the environmental standard. Throughout this study, we produced the low temperature pyrolysis equipment (GTPK-001) as mentioned above, and we found out that the technique can be commercialized economically as well as environmentally friendly.

• The Journal of Advanced Prosthodontics
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• v.8 no.6
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• pp.479-488
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• 2016

PURPOSE. The aim of this study was to test the modulus of elasticity (E) across the interfaces of yttria stabilized zirconia (YTZP) / veneer multilayers using nanoindentation. MATERIALS AND METHODS. YTZP core material (KaVo-Everest, Germany) specimens were either coated with a liner (IPS e.max ZirLiner, Ivoclar-Vivadent) (Type-1) or left as-sintered (Type-2) and subsequently veneered with a pressable glass-ceramic (IPS e.max ZirPress, Ivoclar-Vivadent). A $5{\mu}m$ (nominal tip diameter) spherical indenter was used with a UMIS CSIRO 2000 (ASI, Canberra, Australia) nanoindenter system to test E across the exposed and polished interfaces of both specimen types. The multiple point load - partial unload method was used for E determination. All materials used were characterized using Scanning Electron Microscopy (SEM) and X - ray powder diffraction (XRD). E mappings of the areas tested were produced from the nanoindentation data. RESULTS. A significantly (P<.05) lower E value between Type-1 and Type-2 specimens at a distance of $40{\mu}m$ in the veneer material was associated with the liner. XRD and SEM characterization of the zirconia sample showed a fine grained bulk tetragonal phase. IPS e-max ZirPress and IPS e-max ZirLiner materials were characterized as amorphous. CONCLUSION. The liner between the YTZP core and the heat pressed veneer may act as a weak link in this dental multilayer due to its significantly (P<.05) lower E. The present study has shown nanoindentation using spherical indentation and the multiple point load - partial unload method to be reliable predictors of E and useful evaluation tools for layered dental ceramic interfaces.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.304-308
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• 2008

The optimal design of two stage evaporation & absorption system which is related to the large temperature difference system was investigated numerically in the absorption refrigeration system. The concentrations at inlet & oulet of absorber are 62.9% and 56.9%, but in two stage absorption system the values are 62.2% and 56.2%. Therefore strong solution & weak solution became diluted than the standard value. The amount of weak solution circulation can be reduced in absorption refrigeration system, and the sensible heat load is more reduced to enhance the COP of system. As UAR is increased, COP becomes larger, and this means the role of top section is more important than bottom section in two stage evaporation & absorption system. But the increase of COP becomes slower at 0.7 of UAR ratio. The performance of Type2 is higher than Type1 in COP with the flow direction of cooling waters. This phenomena is due to the active absorption of vapor -absorption & lower temp. cooling water is more effective. The pressure at bottom section becomes higher & that at top section becomes lower and therefore the circulation rate can be diminished more.