• Journal of the Korean Ceramic Society
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• v.31 no.1
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• pp.69-73
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• 1994

Si3N4 ceramics could be densified above 3.2g/㎤ with pressureless sintering at below 178$0^{\circ}C$ by coating Si3N4 and Y2O3 powder with an alumina sol. Substitution a portion of Al2O3 with AlN improved densification. Additional milling of the coated powder in large improvement in bending strength greater than 800 MPa (4-point).

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.12
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• pp.1880-1886
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• 2007

This study was conducted to examine the effects of different soy-oil and soy-lecithin levels on growth performance, nutrient utilization and serum parameters in broiler chickens. Two hundred and forty 1-day-old Arbor Acres chicks were randomly divided into 4 groups and treated as follows: basal diet with 2% soy-oil (SO); soy-oil and soy-lecithin mixture in proportion of 75/25 (SOL1), 50/50 (SOL2) and 2% lecithin (SL). At the end of the trial (42 d), birds in SOL1 group grew faster (p<0.05) and had better feed conversion efficiency (p<0.05) than other groups while SL group had the lowest performance (p<0.05). The utilization of ether extract was improved in SOL1 group (p<0.05) but apparent metabolizable energy (AME) and utilization of other nutrients decreased in SOL2 and SL group from 19 to 21 d. No significant effects were observed in apparent metabolizable energy, dry matter, crude protein and ether extract but the utilization of calcium and phosphorus was significantly improved in SL group (p<0.05) during 39 to 42 d. The birds fed with lecithin had lower serum total cholesterol and triglyceride than the control group (SO). Broilers fed with 2% lecithin (SL) had the highest insulin level (p<0.05). The results implied that soy-lecithin and soy-oil in a proportion of 25:75 had the highest growth performance and that soy-lecithin had cholesterol lowering capacity.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.11a
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• pp.103-108
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• 2003

A method to determine chromium(III) ion in aqueous solution by chemiluminescence method using a lucigenin entrapped silica sol-gel film has been studied. An optical probe for chromium(III) ion has been prepared by entrapping lucigenin into silica sol-gel film coated on a glass support by dip coating. The chromium(III) optical sensor is based on the catalytic effect of chromium(IIII) ion on the reaction between lucigenin and hydrogen peroxide in basic solutions. The effects of Nafion, DMF and Triton X-100 were investigated to find the optimum condition to minimize cracking and leaching from the probe. The effects of pH and concentrations of lucigenin and hydrogen peroxide on the chemiluminescence intensity were investigated. The chemiluminescence intensity was increased linearly with increasing chromium(III) concentration from $2.5{\times}10^{-4}$M to $8.0{\times}10^{-7}$M and the detection limit was $4.0{\times}10^{-7}$M.

• Journal of International Academy of Physical Therapy Research
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• v.7 no.2
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• pp.1037-1040
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• 2016

This study aims to investigate the effects of ankle foot orthosis(AFO) on the activities of tibialis anterior(TA), soleus(Sol), rectus femoris(RF) and biceps femoris(BF) during stairs descending. The activities of TA, Sol, RF and BF were initially measured while descending 4 stairs without using AFO. The activities of the same muscles were then measured again while descending 4 stairs while using AFO. Wilcoxon signed-rank tests were used to analyze the results in order to examine the differences between the with using AFO and without using AFO. Although the activities of TA, Sol and RF were relatively lower while using AFO than without using AFO, only the differences in Sol and RF activities were significant(p<0.05). The activity of BF was relatively higher while using AFO compared to the activity of BF observed without using AFO. However, difference was not significant(p>0.05). Conclusion of this study was observed since AFO's ground reaction force absorption during stairs descending reduced the need to use So and RF that is related to shock absorption. BF activity was increased with AFO than without during standing forward to correct the trunk stability.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.557-560
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• 2003

The submicron $YBa_2Cu_3O_x$ powder was prepared by the sol-gel method. The particle size is distributed from 0.2 to $1.0\;{\mu}m$, which benefits to eliminate the micro-cracks formed in the $YBa_2Cu_3O_x$ films deposited by electrophoresis. The powder was single phase of $YBa_2Cu_3O_x$ examined by X-ray diffraction. In the sol-gel process the citrate gel was formed from citric acid and nitrate solution of $Y_2O_3$, $Ba(NO_3)O_2$ and CuO. When pH values were adjusted to $6.4{\sim}6.7,\;Ba(NO_3)O_2$ could be dissolved in the citrate solution completely. Appropriate evaporative temperature of the sol-gel formation is discussed. After the heat treatment the transition temperature($T_c$) and critical current density($J_c$) of the $YBa_2Cu_3O_x$ samples made of the submicron powder were measured.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.175-178
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• 1998

LiMn$_2$O$_4$-based spinels has been studied extensively as positive electrode materials for rechargeable lithium and lithium ion batteries. We describe here that LiMn$_2$O$_4$ cathode active materials is preparated by sol-gel process using water as solvent, which often yields inorganic oxides of excellent phase purity and well-controlled stoichiometry. Using this process, it has been possible to synthesize phase-pure crystalline spinel LiMn$_2$O$_4$ by calcining the appropriate precursors in air at 80$0^{\circ}C$ for several hours. The influence of different time have also been explored. LiMn$_2$O$_4$ preparated in the present study exhibit the single phase of cubic and active reaction at 400 ~ $600^{\circ}C$. Electrochemical studies show that the this method- synthesized materials appear to present reversible oxidation and reduction reactions at 3.0V ~ 4.5V and cycle stability during 50 cycle.

• Korean Journal of Materials Research
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• v.13 no.4
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• pp.219-223
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• 2003

Zirconia gels dispersed with fine Au particles have been prepared by the sol-gel method. Starting solution with (OC$Zr_4$$H_{ 9}$)$_4$, $C_4$ $H_{9}$ OH, $H_2$O,$ HNO_3$, $HAuC1_4$ was used to prepare gels in several molar ratio. After hydrolysis, viscosity of solutions as 4∼5 cP and gelling time of sols were spent about 9 days. As the heat-treatment temperature was increased,$ ZrO_2$ had the phase transition from tetragonal to monoclinic at $750^{\circ}C$. Heat-treatments of the gel have performed at 500, 700, 750, 800, 1000 and $1100^{\circ}C$ for 3 hrs, respectively. We have investigated TG-DTA, X-ray diffraction patterns, SEM and EDS. The size of Au fine particles dispersed in the heat-treatmented gel was about 0.15∼0.23 $\mu\textrm{m}$ and the shape was most sphericity.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.1989-1991
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• 2005

Lithium titanium oxide as anode material for energy storage prepared by novel synthesis method. $Li_4Ti_5O_{12}$ based spinel-framework structures are of great interest material for lithium-ion batteries. We describe here $Li_4Ti_5O_{12}$ a zero-strain insertion material was prepared by novel sol-gel method and by high energy ball milling (HEBM) of precursor to from nanocrystalline phases. According to the X-ray diffraction and scanning electron microscopy analysis, uniformly distributed $Li_4Ti_5O_{12}$ particles with grain sizes of 100nm were synthesized. Lithium cells, consisting of $Li_4Ti_5O_{12}$ anode and lithium cathode showed the 173 mAh/g in the range of $1.0{\sim}3.0V$. Furthermore, the crystalline structure of $Li_4Ti_5O_{12}$ didn't transfer during the lithium intercalation and deintercalation process.

• Journal of the Korean Ceramic Society
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• v.29 no.9
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• pp.739-749
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• 1992

The sols prepared by dialyzing solutions, in which the hydrolyzed precipitates of TEOT or directly Ti(OC3H7)4 were resolved, were the nanoparticulate sol with the average particle size less than 7 nm and the anatase crystal phase. In the pH range of 1.5 to 2.9, the particle size of the nanoparticulate TiO2 sols (0.09 mol/ι) increased gradually upto 15 nm~26nm with the increase of pH in the initial aging state but the sols were transparent all the time, and stable without growin any more after 30 days. When the slipcasted porous alumina tubes were coated by the sol-gel dipping method, the minimum particle size and the aging time for forming the coated gel layer at the given pH were optimized. For obtaining the very thin crack-free and reproducible membrane coating, the use of a nanoparticulate TiO2 sol (0.09 mol/ι) aged for about 30 dyas at pH=2.0 was found to be the best.

• Journal of the Korean Ceramic Society
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• v.37 no.10
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• pp.981-986
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• 2000

Er(NO$_3$)$_3$.5$H_2O$, Mn($CH_3$$CO_2$)$_2$.4$H_2O$를 출발원료로 사용하여 졸-겔법으로 제조한 ErMnO$_3$박막의 열처리 온도 및 기판 배향성에 따른 박막 배향성과 누설 전류 특성에 관하여 연구하였다. ErMnO$_3$박막은 75$0^{\circ}C$ 이하의 온도에서 1시간 열처리 시비정질상태였으나, 78$0^{\circ}C$ 이상의 온도에서 hexagonal pahse인 ErMnO$_3$로 결정화되었다. 열처리 온도가 증가할수록 기판 배향성과 무관하게 모든 방향으로 결정이 성장함을 알 수 있었다. 결정화 정도와 결정 성장 축에 따라 누설 전류 값이 변화함을 알 수 있었고, 80$0^{\circ}C$에서 열처리한 시편에서는 누설 전류 변화가 비선형적인 경향으로 증가하였으며, $10^{-5}$ A/$ extrm{cm}^2$ 이하로 유지되었다.