• Journal of the Korean Ceramic Society
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• v.43 no.1 s.284
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• pp.16-21
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• 2006

The preparation of $TiB_2$ by SHS in $B_2O_3-Mg-TiO_2$ system was investigated in this study. In the preparation of $TiB_2$, the effect on reactivity and reaction products of the initial pressure of inert gas in reactor, the content of Mg and $TiO_2$ in mixture was investigated. The minimum initial pressure of inert gas in reactor for SHS reaction in this system was 5atm, and as the pressure increased, the concentration of unreacted Mg decreased and combustion temperature increased. At the initial inert gas pressure in reactor of 50atm, the optimum composition for the preparation of pure $TiB_2$ was $B_2O_3+5Mg+TiO_2$. The $TiB_2$ synthesized in this condition had an irregular shape and the particle size of $1\~3{\mu}m$.

• Textile Coloration and Finishing
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• v.4 no.4
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• pp.97-103
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• 1992

For manufacturing a high sorptive ACF, we used orthognal array experimental design to get optimum condition. The ability of ACF was measured by $CCl_4$ adsorption and showed those manufacturing conditions were effective in the order of treatment time>oxidative gas>treatment temperature. The optimal condition presented the maximum adsorption rate was at 90$0^{\circ}C$ for 6 minutes with $CO_2$/$H_2O$ gas in the PAN based ACF manufacturing process. The adsorption rate of developed ACF in this experiment was over 100%.

• Journal of the Korean Ceramic Society
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• v.45 no.7
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• pp.418-422
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• 2008

The preparation of FeB by SHS in $B_2O_3-Mg-Fe-Fe_3O_4$ system was investigated in this study. In the preparation of FeB, the effects of the initial pressure of inert gas in reactor, the content of Mg and $Fe_3O_4$ in mixture on the reactivity and reaction products was investigated. The minimum initial pressure of inert gas in reactor for SHS reaction in this system was 25 atm, and as the pressure increased, the concentration of unreacted Mg decreased and combustion temperature increased. At the initial inert gas pressure in reactor of 25 atm, the optimum composition for the preparation of pure FeB was $1.5B_2O_3$+3.43Mg+ 1.7Fe+$0.1Fe_3O_4$. The FeB synthesized in this condition had an irregular shape and the particle size of $5\;{\mu}m$.

• Journal of the Korean Applied Science and Technology
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• v.20 no.1
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• pp.44-50
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• 2003

We studied on the preparation and evaluation of O/W type microemulsion containing "wax, liquid paraffine and quaternary ammonium salt". And also it was obtained to stability of microemulsions by mono ethylene glycol(MEG) addition. The microemulsions were generally prepared at 96${\sim}$97$^{\circ}C$ by the phase inversion method. We used polyoxyethylene(20) sorbitan monooleate(POE(20)SMO) and distearyl dimethyl ammonium chloride(D.D.A.C.) as the emulsifiers at microemulsion preparation. From the results, we could get best condition for microemulsion preparation, in case of oil phase, montanic ester wax ; 1.1wt%, paraffine wax ; 1.1wt%, liquid paraffine ; 3.1wt%, propylene glycol ; 0.6wt% and ethylene glycol monobutyl ether ; 0.6wt%, when the ratio(wt%) of D.D.A.C. and POE(20)SMO were 2 : 3. And also we could obtained that the distributed particle size of the final microemulsions were about 8${\pm}$1.5nm and the mean particle size was 7${\pm}$0.5nm. We got following results from final microemulsions that the percent of transmittance; 96${\sim}$98% at 700nm. And the microemulsion blended with MEG of 5${\sim}$15wt% showed smaller particle size and more stable distribution than non-containing MEG.

• Journal of the Korean Ceramic Society
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• v.44 no.1 s.296
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• pp.37-42
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• 2007

The preparation of $TiC_{0.7}N_{0.3}$ powder by SHS in the system of $Ti-TiH_2-C$ ($N_2$ atmosphere) was investigated in this study. In the preparation of $TiC_{0.7}N_{0.3}$ powder, the effect of gas pressure, compositions such as Ti, $TiH_2$, C, and additive in mixture on the reactivity were investigated. At 50 atm of the initial inert gas pressure in reactor, the optimum composition for the preparation of pure $TiC_{0.7}N_{0.3}$ was $0.75Ti+0.25TiH_2+0.7C+0.5NaCl$. The $TiC_{0.7}N_{0.3}$ powder synthesized in this condition was a single phase with irregular shape.

• Journal of the Korean Ceramic Society
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• v.43 no.10 s.293
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• pp.595-600
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• 2006

The preparation of $\beta$-SiAlON powder by SHS in the system of $Si-Al-SiO_2-NH_4F(\beta-Si_3N_4)$ was investigated in this study. In the preparation of SiAlON powder, the effect of gas pressure, compositions such as Si, $NH_4F$, \beta-Si_3N_4$ and additive in mixture on the reactivity were investigated. At 50 atm of the initial inert gas pressure in reactor, the optimum composition for the preparation of pure $\beta$-SiAlON was $3Si+Al+2SiO_2+NH_4F$. The $\beta$-SiAlON powder synthesized in this condition was a single phase $\beta$-SiAlON with a rod like morphology.

• Journal of Family Resource Management and Policy Review
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• v.18 no.4
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• pp.27-52
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• 2014

This study aims to investigate the financial soundness of Korean households and its effects on the retirement preparation of these households. The sample consisted of 1,031 households selected from the 4th Korean Retirement and Income Study (KReIS) by the National Pension Research Institute in 2012. The empirical results are as follows. According to the logistic regression model, the statistically significant factors affecting the retirement preparation of Korean households are gender, occupation type, residence, satisfaction with economic condition, and type of financial soundness-sound households or insolvency-risky households. In other words, more female-headed households and households with higher levels of occupation are less likely to prepare for retirement. The households that are more likely to prepare for retirement are those that are lived in metropolitan areas as opposed to the countryside; further, households that are more economically sound are also more likely to prepare for retirement. In particular, sound households and insolvency-risky households are less likely to prepare for retirement compared to liquidity-risky households.

• Journal of Korean Neurosurgical Society
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• v.29 no.9
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• pp.1161-1170
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• 2000

Objective : The transverse hippocampal slice is one of the most commonly studied in vitro models of mammalian brain physiology. However, despite its broad usage, there has been no standardization of slice preparation techniques or recording condition. It is well known that variations in recording conditions can result in profound different effects to neuronal responses. Evoked field potentials, recorded extracellularly, were used to investigate the effects of variations in hippocampal slice preparation protocol on hypoxia responses of CA1 neurones. Material & Methods : Before hypoxic injury, hippocampal slices were incubated for 4 hours. During incubation period, the slices were placed in a incubation chamber($21^{\circ}C$) for recovery from preparation injury and then transferred to recording chamber($34^{\circ}C$) for more recovery and baseline electric recording with current stimulation(0.1Hz). Various time periods in incubation chamber and recording chamber were applied to each experimental group(group 1=60min : 180min, group 2=90min : 150min, group 3=180min : 60min, time in incubation chamber : time in recording chamber) before 10 min hypoxia produced by replacing 95% $O_2$+5% $CO_2$ mixed gas to 95% $N_2$+5% $CO_2$ gas. Calcium, Magnesium ions and several drugs effecting on glutamate receptor also were studied. Recoveries from hypoxic injury of hippocampal slices were estimated by percent recovery of population spike(PS). Statistic analysis of study were performed using paired t-test. Results : The percent recovery of PS after 10min hypoxia was considerably enhanced by increasing the period of current stimulation during incubation period before hypoxic injury. Temperature effect on the result of this experiment was also studied(group 4) but the result from this showed no statistic significance. Low magnesium ion concentration of artificial CSF(Mg-free aCSF) during incubation period enhanced the recovery of PS but low calcium (calcium-free) and high magnesium ion concentration(2mM) reduced it after hypoxic injury. L-glutamate($100{\mu}M$) and AP-5($50{\mu}M$) had no effect on the recovery of PS but CNQX($10{\mu}M$) in artificial CSF during incubation period markedly enhanced the recovery of PS. Co-treatment of AP-5($50{\mu}M$), CNQX($10{\mu}M$) and high magnesium concentration(2mM) enhanced recovery of PS in immediate following period of hypoxic injury but the effect of cotreatment after then decayed rapidly and lost statistic significance. Conclusions : Judging from above results, the condition of baseline recording is important in observing the recovery of population spike after hypoxia, and the time and the condition should be controled more strictly to obtain reliable results.

• Journal of the Korean Society of Industry Convergence
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• v.19 no.4
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• pp.237-244
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• 2016

This paper investigates the possibility to increase the economic value of the thinned young apple trough fermentation process. It is studies the optimal fermentation condition of thinned young apple by manipulating preparation treatment and sugar content. To do this following steps are done. Firstly, different preparation treatment for thinned young apple such as whole apple, cutting apple, and blending apple were done. The different sugar content such as $24^{\circ}Brix$, $15^{\circ}Brix$ and $4^{\circ}Brix$ was added. Secondly, the sugar contents and pH level were measured during fermentation process. Finally, statistical analysis was used to examine the relation between the preparation treatment, sugar content and pH level during the fermentation process. The experimental result shows that the different preparation treatment influences to the fermentation process. The blending apple treatment gave lower pH level compared to other kind treatments. The sugar content of thinned young apple was decrease during the fermentation process. The statistical analysis shows that the manipulation preparation treatment and sugar content affect the final pH level and whole fermentation process. Experimental result shows that the thinned young apple fermentation could be proposed as new alternative product in the market. The best fermentation process was obtained from blending thinned young apple treatment with $24^{\circ}Brix$.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.1
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• pp.59-65
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• 2015

In this study, we evaluated optimum condition of enzyme with pH and temperature for preparation of microfibillated cellulose(MFC). Well-known endo-glucanase, three enzymes were used and CMC was used for substrate. Enzyme activity was evaluated using DNS method and absorbance with UV/VIS spectrophotometer. The enzyme shown the greatest activity was reacted with pulps at optimum condition for 1 hour and treated pulps beated until 100 mL CSF. Enzyme B and Enzyme L was the higher enzyme activity below 0.1% concentration and Enzyme N was the lowest enzyme activity. At various pH and temperature conditions, enzyme activity of Enzyme B was higher than the others at the same concentration. Especially enzyme activity at $50^{\circ}C$ of Enzyme B was almost not changed over pH 6.0. Optimum condition of three enzyme was pH 6 or pH 7 and $50^{\circ}C$ or $60^{\circ}C$. Also beating efficiency of enzyme treated pulps with Enzyme B is 55.6%.