• Korean Journal of Fisheries and Aquatic Sciences
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• v.8 no.1
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• pp.7-10
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• 1975

The catches of mackerel by monofilament and multifilament net were compared by means of $x^2$ and t-test method. In order to improve the netting twine of drift nets, 6 shoots 5 different mesh and nylon-monofilament netting twines $(B\times2,\;C\;D,\;F,)$ and 2 shoe nylon-multifilament $(A\times2)$ which are using near the Jeju Island in contemporary days were used for the experiment. These gill no were connected in order of A, ,B, C, A, B, E, F and operated fly fishing boat Taeann Ho (7T) near sea of Jeju Ialand from May 1974 to August 1974. The results obtained are as follows: 1. B type nylon-monofilament gill nets were superior to nylon-multifilament gill nets in catch according to the result of $X^2$ test and t-test, and the catch ratio was $M_A:\;M_B=1:1.8$. 2. 75mm mesh size C, D nylon-monofilament gill nets were superior to 85mm mesh size nylonmonofilament gill nets, and their catch ratio were E, F: C, D=1:2.8. 3. The catch ratio C, D and E, F type nets were compared by means of t-teat, however could not recognized their relationship.

• Resources Recycling
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• v.27 no.4
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• pp.57-64
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• 2018

Water leaching of tungsten(W) and vanadium(V) was researched from their oxides through mechanochemical (MC) reaction with alkali compounds. Intensive grinding for the mixture of tungsten/vanadium oxide and alkali compounds (NaOH, $Na2CO_3$) was carried out with change of their mixing ratios and grinding duration. Water soluble compounds, $Na_2WO_4$ and $NaVO_3$, were synthesized through MC reaction and their solubilities increased in proportion to the mixing ratio of sodium compound and grinding times. Whereas vanadium leachability was less affected by the mixting ratio and grinding times. The leachabilities of 99.0% were accomplished by a short period of MC treatment, W (30 min.) and V (5 min.). This process enable us to extract W and V from their oxides via a water leaching, and can be applied to the selective recovery of W and V from $DeNO_x$ spent catalysts.

• Journal of the Korean Society of Radiology
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• v.6 no.6
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• pp.499-505
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• 2012

The purpose of this study was to find out the difference of radiation dose value through energy, exposure number, fluoroscopy time, the number of days of exposed scatter X-ray when TLD and OSLD is used in diagnostic radiology. The difference of value were measured by relative ratio and interval. Energy makes high relative ratio of TLD($1.81{\pm}0.41$) than OSLD($1.40{\pm}0.26$), exposure number makes high of OSLD($1.40{\pm}0.26$) than TLD($2.10{\pm}0.10$). There are no significant differences between relative ratio of TLD and OSLD in fluoroscopy time and the number of days of exposed scatter X-ray. But interval of relative ratio in the number of days of exposed scatter X-ray was narrowed in less 0.2. That means, the measurement of scatter X-ray could more confident in TLD and OSLD than the measurement of direct ray. In conclusion, we have to recognize the relative ratio of TLD and OSLD could be vary depending on exposed condition of radiation. And in some cases, double test of TLD and OSLD get more creditable results of dose value.

• Korean Journal of Materials Research
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• v.25 no.2
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• pp.95-99
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• 2015

$NiAl_2O_4$ nanoparticle was synthesized by a reverse micelle processing for inorganic pigment. $Ni(NO_3)_2{\cdot}6H_2O$ and $Al(NO_3)_3{\cdot}9H_2O$ were used for the precursor in order to synthesize $NiAl_2O_4$ nanoparticles. The aqueous solution, which consisted of a mixing molar ratio of Ni/Al, was 1:2 and heat treated at $800{\sim}1100^{\circ}C$ for 2h. The average size and distribution of synthesized $NiAl_2O_4$ powders are in the range of 10-20 nm and narrow, respectively. The average size of the synthesized $NiAl_2O_4$ powders increased with an increasing water-to-surfactant molar ratio and heating temperature. The crystallinity of synthesized $NiAl_2O_4$ powder increased with an increasing heating temperature. The synthesized $NiAl_2O_4$ powders were characterized by X-ray diffraction analysis(XRD), a field emission scanning electron microscopy(FE-SEM), and a color spectrophotometer. The properties of synthesized powders were affected as a function such as a molar ratio and heating temperature. Results indicate that synthesis using a reverse miclle processing is a favorable process to obtain $NiAl_2O_4$ spinels at low temperatures. The procedure performed suggests that this new synthesis route for producing these oxides has the advantage of being fast and simple. Colorimetric coordinates indicate that the pigments obtained exhibit blue colors.

• Journal of Aquaculture
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• v.19 no.2
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• pp.99-108
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• 2006

Sex of the Nile tilapia Oreochromis niloticus is mainly determined by an XX/XY system. However, accumulating evidences suggest the existence of additional sex modifying factors including environmental, autosomal and parental influences. In order to investigate the possibility of parental effects on sex ratios of tilapia progenies, in this study, a series of crosses was carried out using gynogenetic clonal fish, neomales, normal males and females, and YY fish. Crosses between clonal XX male and clonal female have yielded only female progenies and no parental influences were observed. However, in the crosses between clonal males and normal females, female parents were significantly associated with the progeny sex ratios ($X^2$=20.046, 7 d.f., p<0.01). Progeny sex ratios from the crosses between neomales and normal females ($X^2$=60.491, 5 d.f and $X^2$=28.072, 2 d.f.) also showed significant association with female parents (P<0.001). The stability of progeny sex ratios from repeated spawns were confirmed by using 6 different parental pairs. In 16 crosses between normal males and normal females, sex ratios of progenies showed clear maternal influences, and further analysis of the results revealed a negative correlation ($r^2$=0.7718, p<0.05) between the sex ratios of progenies from two different males, indicating a strong paternal influence. No statistically significant relationship between survival rates and sex ratios of progenies was observed in any genotypic groups. Taken together, the influence of parental pairs on progeny sex ratios in this species is evident although the cause of this influence is not clear.

• Journal of Pharmaceutical Investigation
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• v.17 no.1
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• pp.1-14
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• 1987

To increase the bioavailability of norfloxacin, inclusion complex of antimicrobial agent norfloxacin with ${\beta}-Cyclodextrin$ was prepared and studied by the solubility method, spectrophotometric methods(UV, IR, $^1H-NMR$), differential thermal analysis, powder X-ray diffractometry, the physical properties, the antimicrobial activity, DNA binding and in situ recirculation technique. The conclusions are summerized as following; 1) The inclusion complexation was identified by means of solubility, spectrophotometry(UV, IR, NMR), DTA and X-ray diffraction. 2) The molar ratio of $norfloxacin-{\beta}-cyclodextrin$ complex was 1 : 1. 3) The stability constant of $norfloxacin-{\beta}-cyclodextrin$ complex was $21.5\;M^{-1}$, and both true and apparent partition coefficients of the inclusion complex were larger than those of norfloxacin. 4) The time required to dissolve 60% $(T_{60}%)$ of the inclusion complex was 120 min. in distilled water and in the artificial intestinal juice, while norfloxacin did not reach to 60% dissolution within 120 min. 5) The antimicrobial activity of the inclusion complex against Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus aureus showed no significant difference compared to that of norfloxacin alone. 6) Studies on binding properties between the inclusion complex and norfloxacin alone to DNA according to equilibrium dialysis showed no significant differency. 7) In situ absorption rates (Ka) of inclusion complex and norfloxacin alone were 0.229 and $0.102hr^{-1}$, respectively.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.1
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• pp.69-76
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• 2023

An experimental study was conducted on a 4-stroke direct injection diesel engine to examine the combustion and emission characteristics of 1-octanol/diesel fuel blends. The concentration of 1-octanol in the fuel blends was 10%, 30%, and 50% by volume. Experiments were conducted by varying the engine torque from 6 Nm to 12 Nm at the same engine speed of 2,700 rpm. Results showed that the fuel conversion efficiency increased as the 1-octanol proportion increased under most experimental conditions. However, the brake specific fuel consumption increased due to the relatively low lower heating value of 1-octanol. The smoke opacity and the concentrations of NO_x and CO emissions generally decreased with brake mean effective pressure as the 1-octanol proportion increased. On the other hand, the unburned hydrocarbon concentration increased with an ascending ratio of 1-octanol.

• Resources Recycling
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• v.29 no.5
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• pp.38-47
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• 2020

In this study, factors affecting the adsorption reaction for the separation/recovery of V and W using Lewatit monoplus MP 600, a strong basic anion exchange resin, from the leachate obtained through the soda roasting-water leaching process from the spent SCR DeNO_X catalyst investigated and the adsorption mechanism was discussed based on the results. In the case of the mixed solution of V and W, both ions showed a high adsorption ratio at pH 2-6, but the adsorption of W was greatly reduced at pH 8. In the adsorption isothermal experiment, both V and W were fitted well at the Langmuir adsorption isotherm, and the reaction kinetics were fitted well at pseudo-second-order. As a result of conducting an adsorption experiment by adjusting the pH with H₂SO₄ to remove Si, which inhibits the adsorption of V and W from the leachate, the lowest W adsorption ratio was shown at pH 8.5. Desorption of W was hardly achieved in strongly acidic solutions, and desorption of V was well performed in both strongly acidic and strongly basic solutions.

• Clean Technology
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• v.21 no.4
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• pp.271-277
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• 2015

A photocatalyst which mixed by the commercialized P25-TiO₂ and a synthesized Ag_xO was used in an appropriate weight ratio to effectively produce hydrogen gas in this study. The Ag_xOs were synthesized with the conventional sol-gel method, and tetramethylammonium hydroxides were added at the synthesis process in order to stabilize the solutions, and then the solutions were heat-treated at the temperatures of -5, 25, and 50 ℃, resulted to obtain the three types of silver oxides. Physicochemical properties of the synthesized Ag_xOs were identified through X-ray diffraction analysis (XRD), scanning emission microscopy (SEM), ultraviolet-visible spectroscopy, and X-ray photoelectron spectroscopy (XPS). In the photolysis results of water/methanol (weight ratio 1:1) solution, the mixture of P25-TiO₂/Ag_xO exhibited a significantly higher hydrogen gases evolution, compared to that of pure P25-TiO₂. Additionally, the addition of H₂O₂ as an supplement oxidant and in Ag_xO synthesized at 50 ℃ improved the hydrogen production efficiency. In particular, the emitted hydrogen gases reached to 13,000 μmol during 8 hours when a mixed catalyst, Ag_xO of 0.1 g and P25-TiO₂ of 0.9 g, were used.

• 한국연소학회:학술대회논문집
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• 2004.06a
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• pp.173-179
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• 2004

Combustion of refuse derived fuel(RDF) and refuse plastic fuel (RPF) was carried out in a lab-scale circulating fluidized bed. Experiment was investigated cold flow visualization. RDF was made by C & tech and RPF was made by KRS. The results include distribution of temperature in the combustion chamber, and concentrations of flue gas such as $O_2$, $CO_2$, CO, $NO_x$ and HCs Micro G.C(gas chromatograph) was employed to find out concentration of He Temperature distribution was different when RDF and RPF were burnt respectably. As air ratio became increased, $CO_2$, CO, and total of HCs emissions were decreased. According to the number of carbon atom of HCs, HC were classified as five kinds of HC.