• Korean Chemical Engineering Research
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• v.40 no.6
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• pp.659-663
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• 2002

The crystallization of NaF driven by adding ethanol was monitored using quartz crystal analyzer (QCA). Adding ethanol to NaF solution reduced the solubility of NaF and consequently led to nucleation and growth of NaF crystals. To investigate the crystallization behavior of NaF, a gold electrode of QCA was modified by anchoring with 2-mercaptoethylamine hydrochloride based on a self-assembly method. Frequency of QCA varied with the amount of NaF adsorbed on the self-assembled layer of 2-mercaptoethylamine hydrochloride, and thereby the process of NaF crystallization could be analyzed indirectly by monitoring the frequency change of QCA. To change the extent of supersaruration of NaF, the amount of ethanol added to the solution was varied from 1 to 5 ml. Then, the effect of the extent of the supersaturation on the crystallization was examined by analyzing the frequency changes of QCA coated with 2-mercaptoethylamine hydrochloride. It was shown that the QCA technique could be well applied for the characterization and analysis of the crystallization behavior of NaF.

• Journal of the Korean Chemical Society
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• v.38 no.2
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• pp.108-121
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• 1994

The retention indices of branched-chain alkane, benzene ring, alcohol, amine, ketone, aldehyde and cyclic compounds were measured at 150, 180 and $210^{\circ}C$ on OV-1701 and OV-1 capillary columns. The group retention factors (GRF) of the substituents and the st` ructure retention factors (SRF) of the molecular structure change are derived from the retention indices of reference compounds and series of homologues. The $GRF_f$ equation of `f'th substituent is $GRF_f\;=\;I_{obs}-(100Z + \sum\limits_{i{\neq}f}GRF_i$ + {\sum}$SRF_i$)and the SRFf equation of `f'th molecular structure group is $SRF_f\;=\;I_{obs}-(100Z + {\sum}GRFi + \sum\limits_{i{\neq}f}SRF_i$). The predicted retention indices for those compound were in agreement, within the error of $\pm2$ and $\pm3%$, with the observed values that were obtained using the OV-1701 and OV-1 capillary column, respectively. The $\Delta$ xi of the substituents and $\Delta$ yi of the molecular structure change according to temperature change are derived from the $\Delta'/^{\circ}C$ of reference compounds and series of homologues. The $\Delta$ xi equation of the `f'th substituent is ${\Delta}x_f = {$\Delta}'/^{\circ}C+ \sum\limits_{i{\neq}f}\Delta$ xi + {\sum}{\Delta}yi\;and\;{\Delta}yi$ equation of the `f'th molecular structure group is ${\Delta}y_f$ = {\Delta}'/^{\circ}C+{\sum}{\Delta}xi +\sum\limits_{i{\neq}f}{\Delta}yi$. The predicted $\Delta'/^{\circ}C$ for these compounds were in agreement, within the error of ${\pm}18%$ and 17%, with the observed values that were obtained using the OV-1701 and OV-1 capillary column, respectively.

• Journal of Bio-Environment Control
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• v.24 no.3
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• pp.153-160
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• 2015

The objectives of this study were to determine optimal length of off-time between irrigation cycles to improve irrigation efficiency using a frequency domain reflectometry (FDR) sensor-automated irrigation (FAI) system for tomato (Solanum lycopersicum L.) cultivation aimed at minimizing effluent from coir substrate hydroponics. For treatments, the 5-minute off-time length between 3-minute run-times (defined as 3R5F), 10-minute off-time length between 3-minute run-times (defined as 3R10F), or 15-minute off-time length between 5-minute run-times (defined as 5R15F) were set. During the 3-minute or 5-minute run-time, a 60mL or 80mL of nutrient solution was irrigated to each plant, respectively. Until 62 days after transplant (DAT) during the autumn to winter cultivation, daily irrigation volume was in the order of 3R5F (858mL) > 5R15F (409mL) > 3R10F (306mL) treatment, and daily drainage ratio was in the order of 3R5F (44%) > 5R15F (23%) > 3R10F (14%). Between 63 and 102 DAT, daily irrigated volume was in the order of 5R15F (888mL) > 3R5F (695mL) > 3R10F (524mL) with the highest drainage ratio, 19% (${\pm}2.6$), at the 5R15F treatment. During the spring to summer cultivation, daily irrigation volume and drainage ratio per plant was higher in the 3R5F treatment than that of the 3R10F treatment. For both cultivations, a higher water use efficiency (WUE) was observed under the 3R10F treatment. Integrated all the data suggest that the optimal off-time length is 10 minutes.

• The Pure and Applied Mathematics
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• v.24 no.3
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• pp.179-190
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• 2017

In this paper, we introduce and solve the following quadratic (${\rho}_1$, ${\rho}_2$)-functional inequality (0.1) $$N\left(2f({\frac{x+y}{2}})+2f({\frac{x-y}{2}})-f(x)-f(y),t\right){\leq}min\left(N({\rho}_1(f(x+y)+f(x-y)-2f(x)-2f(y)),t),\;N({\rho}_2(4f(\frac{x+y}{2})+f(x-y)-2f(x)-2f(y)),t)\right)$$ in fuzzy normed spaces, where ${\rho}_1$ and ${\rho}_2$ are fixed nonzero real numbers with ${{\frac{1}{{4\left|{\rho}_1\right|}}+{{\frac{1}{{4\left|{\rho}_2\right|}}$ < 1, and f(0) = 0. Using the fixed point method, we prove the Hyers-Ulam stability of the quadratic (${\rho}_1$, ${\rho}_2$)-functional inequality (0.1) in fuzzy Banach spaces.

• Bulletin of the Korean Mathematical Society
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• v.54 no.6
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• pp.2165-2182
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• 2017

Let G be a group and $\mathbb{C}$ the field of complex numbers. Suppose ${\sigma}:G{\rightarrow}G$ is an endomorphism satisfying ${{\sigma}}({{\sigma}}(x))=x$ for all x in G. In this paper, we first determine the central solution, f : G or $G{\times}G{\rightarrow}\mathbb{C}$, of the functional equation $f(xy)+f({\sigma}(y)x)=2f(x)+2f(y)$ for all $x,y{\in}G$, which is a variant of the quadratic functional equation. Using the central solution of this functional equation, we determine the general solution of the functional equation f(pr, qs) + f(sp, rq) = 2f(p, q) + 2f(r, s) for all $p,q,r,s{\in}G$, which is a variant of the equation f(pr, qs) + f(ps, qr) = 2f(p, q) + 2f(r, s) studied by Chung, Kannappan, Ng and Sahoo in [3] (see also [16]). Finally, we determine the solutions of this equation on the free groups generated by one element, the cyclic groups of order m, the symmetric groups of order m, and the dihedral groups of order 2m for $m{\geq}2$.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.195-203
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• 2003

Spray and Mixing characteristics of the unlike impinging triplet injectors (F-O-F, O-F-O) were investigated with the variation of the momentum ratio of oxidizer to fuel. The spray pattern was measured using a backlit stroboscopic photography technique, and mixing efficiency was measured using a mechanical patternator. Kerosene/water were used as a propellant simulant. From the experimental results, it is found that a O-F-O type injector has a good atomization. And as the momentum ratio increases, the mixing efficiency decreases rapidly.

• Journal of the Korean Ceramic Society
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• v.21 no.3
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• pp.231-238
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• 1984

Heavy metal fluoride glasses exhibit considerable promise as high transparency materials from the UV to the IR. These glasses are prepared by fusion of the mixture of metal fulorides($ZrF_4$, $BaF_2$, $LaF_3$ etc) at 800-1, 00$0^{\circ}C$ under the inert$(N_2)$ or reactive ($CCl_4$, $Cl_2$) atmosphere following the casting into glass on cooling. Infrared absorption at the 3, 400 cm-1 -OH peak has been measured as a function of thickness for several ZrF-$BaF_2$-LaF and $HfF_4$-$BaF_2$-$LaF_3$ glasses to separate contributions from bulk and surface -OH. For glasses melted under $CCl_4$ reactive atmosphere the peak is due almost entirely to surface-OH. and melting in a closed reactor was best for removing -OH. In ambient atmosphere the -OH peak exhibited no time dependence over a 30 d period indicating a very small rate of surface attack by atmospheric H2O. Removal of -OH absorption processing was generally easier and more complete for the $BaF_2$/ThF4-glasses than for the $ZrF_4$-or $HfF_4$-based glasses.

• The Journal of the Acoustical Society of Korea
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• v.18 no.8
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• pp.75-83
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• 1999

This paper proposes a new F0 contour model for intonation control in speech synthesis. We assume that the F0 contour of an utterance can be described using a sequence of time-overlapping events, which determine the fluctuation of a given F0 contour, described by asymmetric Gaussian functions. In addition, We propose a parameter estimation algorithm for the proposed model. The proposed model is not developed with a particular phonological theory in mind, and can be used in both F0 contour analysis and synthesis. For testing our F0 model, we collected 500 sentences from various genres and built a corresponding speech corpus uttered by a professional female announcer. As n result of F0 resynthesis experiment using the proposed model, the RMSE was 7.87Hz for given speech corpus.

• Journal of the korean academy of Pediatric Dentistry
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• v.11 no.1
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• pp.151-157
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• 1984

The purpose of this study was to compare the growth-inhibiting effect of sodium fluoride and stannous fluoride on a cariogenic strain of Streptococcus mutans exposed to the different concentration of $SnF_2$ and NaF The result were as follows: 1. The growth rate of the Streptococcus mutans was unaffected by 75 ppmF, slowed by 150 ppmF, and immediately arrested by 300 or 600 ppmF where increments of NaF were added to actively growing 12-hour broth culture. 2. $SnF_2$ slowed the growth rate at 75 ppmF, was to bactericidal initially at 150 and 300 ppmF, and was to totally bactercidal at 600 ppmF. 3. $SnF_2$ has been shown to be more effective than NaF in inhibiting the growth activity of Streptococcus mutans. 4. The inhibitory effect of fluoride compounds on the growth of Streptococcus mutans was increased in the decreased pH at concentration of 600 ppmF.

• Korean Journal of Plant Resources
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• v.11 no.3
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• pp.335-344
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• 1998

Percicarp anatomy of Fagophrum was examined on the basis of 12 species and two subspecies to contribute to a better understanding of specific phylogenetic relationship within genus. Examined species have a similar mature pericarp structure, but differences among the species are found with respect to whether or not sclerotic cells are present, and what kind of is the sclerotic cell shape in theexocarp. By the comparisons with pericarp anatomical structure, they are classified into three groups. First clade is composed of F. esculentum , F. esculentum ssp. ancestralis and F. homotropicum ; second clade is consisted of F. tataricum, F. tataricum ssp. potanini and Fl cymosum ; third clade is composed of f. callianthum,F. capillatum, F. gracilipes, F. leptopodum, F.lineare, F. pleioramosum, F.statice and F.urophyllum. The phylogey based on pericarp characters was considerably consistent with ones proposed by previous authors. It also suggested that pericarp characters are useful informatino for deduceing phylogenetic phylogenetic realtionship within geneus Fagopyrum. On the other hand, morphological character evolution indicated that there are tow synapomorphies in genus. There,it was suggested that these species having selfing and homostylous characters are evolved form heterostylous and ourcrossing species.