• Journal of the Korean Ceramic Society
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• v.41 no.2
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• pp.97-101
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• 2004

W $O_{x}$-based semiconductor type thin film gas sensor was fabricated for the detection of N $O_{x}$ by reactive d.c. sputtering method. The relative oxidation state of the deposited W $O_{x}$ films was approximately compared by the calculation of the difference of the binding energy between Ols to W4 $f_{7}$2/ core level XPS spectra in the standard W $O_3$ powder of known composition. As the annealing temperature increased from 500 to 80$0^{\circ}C$, relative oxygen contents and grain size of the sputtered films were gradually increased. As the results of sensitivity ( $R_{gas}$/ $R_{air}$) measurements for the 5 ppm N $O_2$ gas, the sensitivity was 110 and the sensor showed recovery time as fast as 200 s. The other sensor properties were examined in terms of surface microstructure, annealing temperature, and relative oxygen contents. These results indicated that the W $O_3$ thin film with well controlled structure is a good candidate for monitoring and controlling of automobile exhaust.haust.t.t.t.

• Bulletin of the Korean Chemical Society
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• v.10 no.6
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• pp.582-585
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• 1989

Two crystal structures of dehydrated $Sr^{2+}\;and\;Tl^+$ exchanged zeolite A, $Sr_xTl_{12-2x}-A$ (x = 1.6 and 5.45), have been determined by single-crystal X-ray diffraction techniques. Their structures were solved and refined in the cubic space group Pm3m at $21(1)^{\circ}C.$ Both crystals were ion exchanged in flowing streams of mixed $Sr(NO_3)_2\;and\;TlNO_3$ aqueous solution, followed by dehydration at $360^{\circ}C\; and\; 2${\times}$10^{-6}$ Torr for 2 days. Full-matrix least-squares refinements of the dehydrated $Sr_{1.6}Tl_{8.8}-A (a = 12.214(2){\AA})\; and\;Sr_{5.45}Tl{1.1}-A (a=12.291(2){\AA})$ have converged to final error indices, $R_1=0.055\; and\;R_2=0.061$ with 286 reflections, and R1 = 0.072 and R2 = 0.090 with 217 reflections, respectively, for which$\;I\;{>}\;3{\sigma}(I)$. In both structures, all Sr(II) ions are coordinated by three framework oxygens; Sr(II) to O(3) distances are $2.21(2){\AA}\;for\;Sr_{1.6}Tl_{8.8}-A \;and\;2.31(1){\AA} \;for\;Sr_{5.45}Tl_{1.1}-A,$and Tl(I) to O(3) distances are $2.657(6){\AA}\;for\;Sr_{1.6}Tl_{8.8}-A\;and\;2.845(8){\AA}\;for\;Sr_{5.45}Tl_{1.1}-A,$ respectively. In each structure, the angle subtended at Sr(II), O(3)-Sr(II)-O(3) is $118.7(4)^{\circ}\;for\; Sr_{1.6}Tl_{8.8}-A \;and\;120.0(4)^{\circ}\;for\;Sr_{5.45}Tl_{1.1}-A.\;Sr^{2+}$ ions prefer to 6-ring sites and $Tl^+$ ions to 8-ring sites when total number of ions per unit cell is more than 8.

• Journal of the Korean Chemical Society
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• v.39 no.1
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• pp.7-13
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• 1995

The crystal sructures of $X(Ca_{46}Al_{92}Si_{100}O_{384})$ and $Ca_{32}K_{28}-X(Ca_{32}K_{28}Al_{92}Si_{100}O_{384})$ dehydrated at $360^{\circ}C$ and $2{\times}10^{-6}$ Torr have been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd3 at $21(1)^{\circ}C.$ Their structures were refined to the final error indices, R_1=0.096,\;and\;R_2=0.068$ with 166 reflections, and R_1=0.078\;and\;R_2=0.056$ with 130 reflections, respectively, for which I > $3\sigma(I).$ In dehydrated $Ca_{48}-X,\;Ca^{2+}$ ions are located at two different sites opf high occupancies. Sixteen $Ca^{2+}$ ions are located at site I, the centers of the double six rings $(Ca(1)-O(3)=2.51(2)\AA$ and thirty $Ca^{2+}$ ions are located at site II, the six-membered ring faces of sodalite units in the supercage. Latter $Ca^{2+}$ ions are recessed $0.44\AA$ into the supercage from the three O(2) oxygen plane (Ca(2)-O(2)= $2.24(2)\AA$ and $O(2)-Ca(2)-O(2)=119(l)^{\circ}).$ In the structure of $Ca_{32}K_{28}-X$, all $Ca^{2+}$ ions and $K^+$ ions are located at the four different crystallographic sites: 16 $Ca^{2+}$ ions are located in the centers of the double six rings, another sixteen $Ca^{2+}$ ions and sixteen $K^+$ ions are located at the site II in the supercage. These $Ca^{2+}$ ions adn $K^+$ ions are recessed $0.56\AA$ and $1.54\AA$, respectively, into the supercage from their three O(2) oxygen planes $(Ca(2)-O(2)=2.29(2)\AA$, $O(2)-Ca(2)-O(2)=119(1)^{\circ}$, $K(1)-O(2)=2.59(2)\AA$, and $O(2)-K(1)-O(2)=99.2(8)^{\circ}).$ Twelve $K^+$ ions lie at the site III, twofold axis of edge of the four-membered ring ladders inside the supercage $(K(2)-O(4)=3.11(6)\AA$ and $O(1)-K(2)-O(1)=128(2)^{\circ}).$

• Fisheries and Aquatic Sciences
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• v.6 no.4
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• pp.220-224
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• 2003

In order to determined the appropriate processing season of Pacific oyster (Crassostrea gigas), 30 individuals cultured in Kamak Bay on the southern coast of Korea were taken bimonthly 7 times a year, and seasonal variation of edible portion weight, edible portion yield and coefficient of fatness were investigated. There were close relationships between edible portion weight (X) and total weight (Y) and between coefficient of fatness (X) and edible portion yield (Y), which were expressed in regression lines, i.e. Y=0.2709X-1.9094 (r=0.9254) and Y=44.0596X+ 15.1127 (r=0.8485), respectively. From the results of seasonal variation of edible portion weight, yield and coefficient of fatness, the appropriate processing season of raw Pacific oyster was between winter and spring, that is, between December and following April the next year.

• Korean Journal of Crystallography
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• v.6 no.2
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• pp.103-110
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• 1995

The crystal structure of 1-Cyclopropyl-7-(2,7-diazabicyclo[3.3.0]oct-4-en-7-yl)-6-fluoro-8-methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (HCI salt) has been determined from single crystal x-ray diffraction study ; C20H21N3O4FCl, Monoclinic, C2/c, a=28.349(2)Å, b=11.941(2)Å, c=12.806(2)Å, β=96.428(9)°, V=4307.8Å3, T=296(2)K, Z=8, CuKα(λ=1.5418Å). The molecular structure was solved by direct method and refined by full-matrix least squares to a final R=4.96% for 2258 unique observed F0>4σ(F0) reflections and 293 parameters. The conformation of the molecule is stabilized by an intramolecular O(28)-H(28)…O(25) [2.517(4)Å, 156.7(447)°] hydrogen bond. Intermoleculars distances correspond to van der Waals contacts.

• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1393-1406
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• 2018

In this study, three parameters (Pressure ($X_1$), Airflow rate ($X_2$), Operation time ($X_3$)) were experimentally designed and the predicted model and optimal conditions were established by using the terminal rise velocity of the microbubbles as the response value. The polynomial regression analysis showed that the optimum value for the terminal rise velocity at the Pressure ($X_1$) of 4.5 bar, Airflow rate ($X_2$) of 3.3 L/min and Operation time ($X_3$) of 2.2 min was 5.14 cm/min ($85.7{\mu}m/sec$). Also, the highest microbubble diameter size distribution in the range of 2 to $5{\mu}m$ and 25 to $50{\mu}m$ was confirmed by using a laser particle counting apparatus.

• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.2143-2147
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• 2014

Ketene-forming elimination from 2-X-4-nitrophenyl furylacetates (1a-d) promoted by $R_2NH-R_2NH_2{^+}$ in 70 mol % MeCN(aq) has been studied kinetically. When X = Cl and $NO_2$, the reactions exhibited second-order kinetics as well as Br$\ddot{o}$nsted ${\beta}$ = 0.37-0.54 and $|{\beta}_{lg}|$ = 0.31-0.45. The Br$\ddot{o}$nsted ${\beta}$ decreased with a poorer leaving group and $|{\beta}_{lg}|$ increased with a weaker base. The results are consistent with an E2 mechanism. When the leaving group was changed to a poorer one [X= H (1a) and $OCH_3$ (1b)], the reaction mechanism changed to the competing E2 and E1cb mechanisms. A further change to the E1cb mechanism was realized for the reaction of 1a with $i-Pr_2NH/i-Pr_2NH_2{^+}$ in 70 mol % MeCN-30 mol % $D_2O$. By comparing the kinetic results in this study with the existing data for $ArCH_2C(O)OC_6H_3-2-X-4-NO_2$, the effect of the ${\beta}$-aryl group on the ketene-forming elimination was assessed.

• Journal of Oral Medicine and Pain
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• v.7 no.1
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• pp.59-65
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• 1982

For the purpose of estimation of age based on changes in the human root dentin transparency, 173 extracted teeth in each part of upper & lower Lt. & Rt. central, lateral incisors to Lt. & Rt. 2nd premolars were evaluated and analized in terms of root dentin transparency. The results are as follows : 1. It was reconfirmed that there exisits coparatively close correlatonship between age and the root dentin transparency. 2. It was proved that the correlation between the changes in the length and the area of the root dentin transparecy in accordance with the ages of each tooth was highest at the upper central incisor, and next at the low central incisor and the upper second premoloar respectively. 3. In the analysis of the age of the transparency, the error was less in the measurement of the area than in the measurement of the length in regard to the estimation of age. 4. The results from the test of the upper central incisor were boiled down to the following linear equation about the correlation among the area and the length of the transparency, and the age: Y=6.94X+14.7(r=0.59) (Y:estimated age, X:length mm) Y=138.47X+12.31(r=0.72) (Y:estimeted age, $X:area\textrm{cm}^2$)

• Journal of applied mathematics & informatics
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• v.7 no.3
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• pp.1017-1027
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• 2000

On the positive real number, we obtain the Hyers-Ulam stability and a stability in the sense of R. Ger for the generalized beta function g(x+p,y+q) = ${\varphi}(x,y)g(x,y)$ in the following settings: $$\mid$g(x+p,y+q)-{\varphi}(x,y)g(x,y)$\mid${\leq}{\delta}$ and $$\mid$\frac{g(x+p,y+q)}{\varphi(x,y)g(x,y)}-1$\mid${\leq}{\psi}(x,y). As a consequence we obtain stability theorems for the gamma functional equation and the beta functional equation.

• Korean Journal of Medicinal Crop Science
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• v.14 no.4
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• pp.250-254
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• 2006

To elucidate cytogenetic differences, karyotype analysis and FISH (fluorescence in situ hybridization) with 45S and 5S rDNAs were carried out in the three Astragalas species: Astragalas membranaceus Bunge, A. membranaceus var. alpinus Nakai and A. mongholicus Bunge. The somatic metaphase chromosome numbers of all three species were 2n=2x=16 and the size of chromosomes ranged $2.19{\sim} 5.73\;{\mu}m$. The chromosome complement of A. membranaceus consisted of each four pairs of metacentrics (chromosomes 3,4,6 and 7) and submetacentrics (chromosomes 1,2,4 and 8). In A. membranaceus var. alpinus, the chromosome complement consisted of two pairs of metacentrics (chromosomes 4 and 8) and six pairs of submetacentrics (chromosomes 1,2,3,5,6 and 7). A. mongholicus had three pairs of metacentrics (chromosomes 6,7 and 8) and five pairs of submetacentrics (chromosomes 1,2,3,4 and 5). Using bicolor-FISH, one pair of 45S and 5S rDNA signals could be detected on the centromeric regions of chromosomes 8 and 7 of A. membranaceus and A. mongholicus, respectively. In contrast, A, membranaceus var. alpinus had one pair of 45S signals on the centromeric region of chromosome 8 and two pairs of 5S rDNA signals on the short arms of chromosomes 7 and 8.