• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.1
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• pp.8-11
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• 2006

The magnetic properties and crystal structures of $Sm_yGd_{2-y}Fe_{17-x}Si_x$ alloys ($0\leq\;x\leq2\;and\;y=0\~1.67$) have been investigated using x-ray diffraction and magnetic measurements. The $Sm_yGd_{2-y}Fe_{17-x}Si_x$ specimens were crystallized to the rhombohedral $Th_2Zn_{17}-structure$ with less than $5mol\%$ of impurities. The unit cells of the mixed rare-earth samples are smaller than those of $Sm_2Fe_{17}\;and\;Gd_2Fe_{17}.$ For example, the $T_c\;of\;SmGdFe_{17}\;(255^{\circ}C)$ is approximately 160 and $800^{\circ}C)$ higher than that of $Sm_2Fe_{17}\;and\;Gd_2Fe_{17},$ respectively. The $T_cs$ measured for $Sm_yGd_{2-y}Fe_{17-x}Si_x$ samples, 280 to $290^{\circ}C)$, are among the highest values observed for a $R_2Fe_{17-x}M_x$ intermetallic where M is a substituent other than cobalt.

• Journal of Magnetics
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• v.15 no.4
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• pp.159-164
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• 2010

The Zn, Co and Ni substituted manganese ferrite powders, $Mn_{1-x}$(Zn, Co, Ni)$_xFe_2O_4$, were fabricated by the solgel method, and their crystallographic and magnetic properties were studied. The Zn substituted manganese ferrite, $Zn_{0.2}Mn_{0.8}Fe_2O_4$, had a single spinel structure above $400^{\circ}C$, and the size of the particles of the ferrite powder increased when the annealing temperature was increased. Above $500^{\circ}C$, all the $Mn_{1-x}$(Zn, Co, Ni)$_xFe_2O_4$ ferrite had a single spinel structure and the lattice constants decreased with an increasing substitution of Zn, Co, and Ni in $Mn_{1-x}$(Zn, Co, Ni)$_xFe_2O_4$. The Mossbauer spectra of $Mn_{1-x}Zn_xFe_2O_4$ (0.0$\leq$x$\leq$0.4) could be fitted as the superposition of two Zeeman sextets due to the tetrahedral and octahedral sites of the $Fe^{3+}$ ions. For x = 0.6 and 0.8 they showed two Zeeman sextets and a single quadrupole doublet, which indicated they were ferrimagnetic and paramagnetic. And for x = 1.0 spectrum showed a doublet due to a paramagnetic phase. For the Co and Ni substituted manganese ferrite powders, all the Mossbauer spectra could be fitted as the superposition of two Zeeman sextets due to the tetrahedral and octahedral sites of the $Fe^{3+}$ ions. The variation of the Mossbauer parameters are also discussed with substituted Zn, Co and Ni ions. The increment of the saturation magnetization up to x = 0.6 in $Mn_{1-x}Co_xFe_2O_4$ could be qualitatively explained using the site distribution and the spin magnetic moment of substituted ions. The saturation magnetization and coercivity of the $Mn_{1-x}$(Zn, Co, Ni)$_xFe_2O_4$ (x = 0.4) ferrite powders were also compared with pure $MnFe_2O_4$.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.1
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• pp.33-46
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• 2010

We investigated and estimated at the characteristics of decomposition and by-products of N-Nitrosodimethylamine (NDMA) using a design of experiment (DOE) based on the Box-Behken design in an UV process, and also the main factors (variables) with UV intensity($X_2$) (range: $1.5{\sim}4.5\;mW/cm^2$), NDMA concentration ($X_2$) (range: 100~300 uM) and pH ($X_2$) (rang: 3~9) which consisted of 3 levels in each factor and 4 responses ($Y_1$ (% of NDMA removal), $Y_2$ (dimethylamine (DMA) reformation (uM)), $Y_3$ (dimethylformamide (DMF) reformation (uM), $Y_4$ ($NO_2$-N reformation (uM)) were set up to estimate the prediction model and the optimization conditions. The results of prediction model and optimization point using the canonical analysis in order to obtain the optimal operation conditions were $Y_1$ [% of NDMA removal] = $117+21X_1-0.3X_2-17.2X_3+{2.43X_1}^2+{0.001X_2}^2+{3.2X_3}^2-0.08X_1X_2-1.6X_1X_3-0.05X_2X_3$ ($R^2$= 96%, Adjusted $R^2$ = 88%) and 99.3% ($X_1:\;4.5\;mW/cm^2$, $X_2:\;190\;uM$, $X_3:\;3.2$), $Y_2$ [DMA conc] = $-101+18.5X_1+0.4X_2+21X_3-{3.3X_1}^2-{0.01X_2}^2-{1.5X_3}^2-0.01X_1X_2+0.07X_1X_3-0.01X_2X_3$ ($R^2$= 99.4%, 수정 $R^2$ = 95.7%) and 35.2 uM ($X_1$: 3 $mW/cm^2$, $X_2$: 220 uM, $X_3$: 6.3), $Y_3$ [DMF conc] = $-6.2+0.2X_1+0.02X_2+2X_3-0.26X_1^2-0.01X_2^2-0.2X_3^2-0.004X_1X_2+0.1X_1X_3-0.02X_2X_3$ ($R^2$= 98%, Adjusted $R^2$ = 94.4%) and 3.7 uM ($X_1:\;4.5\;$mW/cm^2$, $X_2:\;290\;uM$, $X_3:\;6.2$) and $Y_4$ [$NO_2$-N conc] = $-25+12.2X_1+0.15X_2+7.8X_3+{1.1X_1}^2+{0.001X_2}^2-{0.34X_3}^2+0.01X_1X_2+0.08X_1X_3-3.4X_2X_3$ ($R^2$= 98.5%, Adjusted $R^2$ = 95.7%) and 74.5 uM ($X_1:\;4.5\;mW/cm^2$, $X_2:\;220\;uM$, $X_3:\;3.1$). This study has demonstrated that the response surface methodology and the Box-Behnken statistical experiment design can provide statistically reliable results for decomposition and by-products of NDMA by the UV photolysis and also for determination of optimum conditions. Predictions obtained from the response functions were in good agreement with the experimental results indicating the reliability of the methodology used.

• Journal of Aquaculture
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• v.10 no.3
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• pp.261-271
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• 1997

Ammonia removal capacities of five submerged filter media, 2~3mm sand, 30~50mm gravel, 20~40mm coral sand, polythylene net, and corrugated plastic plate in a seawater recirculating system were tested. A rotating biological contactor (RBC) was also tested for comparison. Oxygen consumption rates were measured along with the ammonia removal efficiencies. The ammonia concentrations in the system were maintained from 0.052 to 0.904 mg/l (mean 0.338$\pm$0.219 mg/l) and the water temperature was ranged from 19.2 to $21.4^{\circ}C\;(mean 20.2^{\circ}C\pm0.58^{\circ}C$). The 1/2-order kinetic model (Y:g/$m^3$/day) and the mean ammonia removal rates (g/$m^3$/day) of the filter media were : Sand : Y=135.5X0.5-25.1(r2=0.8110), 45.1 Coral sand : Y=125.1X0.5-33.0 (r2=0.7307), 31.8 Polyethylene net : Y=87.4X0.5-20.1 (r2=0.6780), 25.2 Corrugated plastic plate : Y=87.4X0.5-20.1(r2=0.5206), 19.2 Gravel : Y=4307X0.5-5.5 (r2=0.2596), 17.1 RBC : Y=127.6X0.5-33.4 (r2=0.7146), 32.8 where X is the concentration of ammonia. Oxygen consumption rates well corresponded to the ammonia removal capacities of each filter medium, thus the sands showing the highest value (442g/$m^3$/day) followed by coral sands (291.1g/$m^3$/day), polyethylene nets (236.9g/$m^3$/day), gravels (135.6g/$m^3$/day) and corrugated plastic plates (134.2g/$m^3$/day). Oxygen consumption rate of the RBC was unable to measure because of the characteristics of the structure.

• The Korean Journal of Mycology
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• v.3 no.1
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• pp.1-19
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• 1975

Since the importance of casing in fruit body formation of Agaricus bisporus has been emphasized, physico-chemical characteristics of casing materials were discussed by many workers and a mixture of peat and mineral soil as proper casing material has been adopted in many of mushroom growing countries. Because of limited resources of peat in Korea, it is necessary to find practical performance and substitutional materials for casing. The effect of casing on mycelial growth and mushroom yield of A. bisporus varied with materials, its combination and practices etc. The experiments to be discussed in this paper are concerned with pH and Ca of casing material which influence A bisporus, and changes of physico-chemical characteristics with mixing ratio of casing materials and its effect on A. bisporus. The optimum range of moisture content of each material, management of watering and application of physico-chemical characteristics casing materials was also investigated and re-use of weathered spent compost for casing material was described. 1. The effect of calcium on mycelial growth of A. bisporus at various pH in Halbschalentest showed different results with calcium sources. Best results were obtained around neutrality and fresh weight of fruit bodies grown in the range of pH 7 to 8 was highest among the tested levels. 2. Available moisture, pore space, organic matter, cation exchangeable capacity and exchangeable cation was increased by an increase of mixing ratio of peat in casing materials, while an adverse effect was obtained by addition of sand. 3. Mycelial growth on clay loam was more rapid at a lower bulk density of 0.75g/cc and at 20% moisture content on a dry weight basis at the same bulk density. 4. Mixing ratio of casing materials, 60 to 80 per cent by volume of peat mixed with 20 to 40 per cent of clay loam produced the highest yield of fresh fruit bodies and sand the lowest. However, per cent of open cap was highest in peat and lowest in sand. 5. Days required for fruit body initiation was shortened in mixtures of peat and clay loam by one to three days compared with other materials and the formation of flushes was clear. 6. The effect of some physico-chemical characteristics of casing materials on the fresh weight of fruit bodies were estimated by a multiple regression equation; Y=-923.86+$8.18X_1+8.04X_2+7.90X_3+0.12X_4+2.03X_5-0.82X_6-0.54X_7$ where $X_1,X_2,X_3,X_4,X_5,X_6,X_7$ are sand, silt, clay, available moistuer, porosity, organic matter and exchangeable cation respectively. The productivity of certain casing material could be predicted from this equation. 7. Fresh weight of fruit bodies was positively correlated with porosity exchangeable cation, organic matter, available moisture, silt and clay of materials; while sand was negatively correlated. On the contrary, sand was the unique factor reducing per cent of open cap. 8. Distribution of three phases of high productive casing material was concentrated in the range of 10 to 30 per cent solids, 15 to 30 per cent liquids, and 50 to 60 per cent in air volume. 9. Fresh weight of fruit bodies from peat was not affected with heavy watering but in clay loam and sandy loam severe crop losses occurred. Fresh weight of individual fruit was increased and open caps were decreased with heavy watering but light watering resulted in adverse effects: its effect was especially great in peat. 10. Optimum range of moisture content by weight on a dry basis was different with each casing material. To maintain optimum moisture content concerned with yield of fruit bodies and open cap, sandy loam and peat mixtures required daily watering of 0.6, 0.6 to 1. 2 and 1.2 to 2.4 liters per $3.3m^2$ of bed area, respectively. 11. Maximum yield of fruit body was recorded in the range of pF 2. 0 to 2. 5 of casing materials if organic matter content was below 4.2 per cent and in pF 1. 3 to 1.8 if above 7.1%. 12. pF curve of a certain casing material could be draws from moisture content at various pF values by multiple regression equations provided texture, organic matter and calcium of the casing material are given. Optimum moisture range of the casing materials also could be estimated by the equation. 13. It was possible to improve the phyico-chemical characteristics of clay loam and sandy loam by addition of weathered spent compost although the effect was less than in the case of peat. Fresh weight of fruit bodies wsa increased by addition of weathered spent compost but its effect was not as remarkable as peat. Accordingly, further studies will be required.

• Journal of Animal Science and Technology
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• v.44 no.4
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• pp.453-458
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• 2002

In order to search for reliable rapid methods of estimating bacterial counts in pork, this study was tried to measure resazurin reduction time which is simple in experimental method, low in analytical cost, able to estimate bacterial count within short time. The results were summarized as follows; Correlation coefficient between initial bacterial log count(25$^{\circ}C$/72hr, Y) and resazurin reduction time(X) from blue color to pink color during incubation at 25$^{\circ}C$ and 30$^{\circ}C$ was higher than other conditions as -0.95 and -0.94, respectively. Considering correlation coefficient and reduction time, incubation temperature was compatible at 30$^{\circ}C$, and regression equation(RE) was Y = -0.4386X + 7.7870. At a bacterial load of $10^2$cfu/$cm^2$, $10^3$cfu/$cm^2$ and $10^4$cfu/$cm^2$ in pork, reduction time was 13.2hr, 10.9hr and 8.6hr, respectively. Correlation coefficient between initial bacterial log count(30$^{\circ}C$/72hr, Y) and resazurin reduction time(X) from blue color to pink color during incubation at 30$^{\circ}C$ was highest among other conditions as -0.93, and RE was Y = -0.4171X + 7.5540. At a bacterial load of $10^2$cfu/$cm^2$, $10^3cfu/$cm^2$ and $10^4cfu/$cm^2$ in pork, reduction time was 13.3hr, 10.9hr and 8.5hr, respectively. Correlation coefficient between initial bacterial log count(35$^{\circ}C$/72hr, Y) and resazurin reduction time(X) from blue color to pink color during incubation at 30$^{\circ}C$ was highest among other conditions as -0.93, and RE was Y = -0.3514X + 6.7513. At a bacterial load of $10^2$cfu/$cm^2$, $10^3$cfu/$cm^2$ and $10^4$cfu/$cm^2$ in pork, reduction time was 13.5hr, 10.7hr and 7.8hr, respectively.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.8 no.1
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• pp.39-42
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• 1978

The effect of irradiation of x-ray to developing rat mandible in the gestation stage was focused on the study of mandible development and the side effect of x-ray irradiation. The author studied the effect of x-ray irradiation with the gestated rat and their off'springs. 100 rads, 200 rads, 300 rads and 400 rads of x-ray was irradiated in regular order schematically at the lower left abdomen of gestated rat. 18½days after conception, their off'springs were sacrificed and exaimined their developing mandible with histological findings. The results were as followed. 1. In the 100-200 rads irradiated rat off'springs, bony trabeclulation was revealed irregular shape. In combine with this finding, osteoblast and fibroblast were appeared shrunken of their nucleus and location of eccentric position. 2. In the 300-400 rads irradiated rat off'springs, decrease of fibroblast and osteoblast appearance in the periosteum were prominently observed and empty lacunae were frequently appeared in their bone matrix. 3. The advent of osteoclast and resorption of cortical bone were appeared in proportion to increasing of x-ray irradiation.

• Korean Journal of Mathematics
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• v.8 no.2
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• pp.121-126
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• 2000

B.Djafari Rouhani and W.A.Kirk [3] proved the following theorem: Let Xbe a reflexive Banach space and $(x_n)_{n{\geq}0}$ be a nonexpansive (resp., firmly nonexpansive )sequence in X. Then the set of weak ${\omega}$-limit points of the sequence $(\frac{x_n}{n})_{n{\geq}1}$(resp., $(x_{n+1}-x_n)_{n{\geq}0$) always lies on a convex subset of a sphere centered at the origin of radius $d={\lim}_{n{\rightarrow}{\infty}}\frac{{\parallel}x_n{\parallel}}{n}$. In this paper we show that the above theorem for nonexpansive(resp., firmly nonexpansive) sequences holds in a general Banach space(resp., a strictly convex dual $X^*$).

• East Asian mathematical journal
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• v.1
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• pp.89-100
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• 1985

A mapping f: X$\rightarrow$Y is introduced to be weakly irresolute if, for each x $\varepsilon$ X and each semi-neighborhood V of f(x), there exists a semi-neighborhood U of x in X such that $f(U){\subset}scl(V)$. It will be shown that a mapping f: X$\rightarrow$Y is weakly irresolute iff(if and only if) $f^{-1}(V){\subset}sint(f^{_1}(scl(V)))$ for each semiopen subset V of Y. The relationship between mappings described in [3,5, 6,8] and a weakly irresolute mapping. will be investigated and it will be shown that every irresolute retract of a $T_2$-space is semiclosed.

• Asian-Australasian Journal of Animal Sciences
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• v.8 no.4
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• pp.375-378
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• 1995

Three month old 600 ducklings of Khaki Campbell/KC Desi and KC X Desi were reared for a period of 13 months in the villages surrounding Bangladesh Agricultural University in order to study the economic traits of duck with and without extra feed to scavenging system of rearing. KC attained earlier sexual maturity followed by KC X Desi and Desi ducks and crossbred showed closeness to sire breed for this trait, KC X Desi found heavier and produce more eggs than their parental breeds. KC showed higher hatchability followed by KC X Desi and Desi ducks were more resistant followed by KC X Desi and KC to diseases. Extra feeding were found more beneficial to ducks irrespective of breed and types.