• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.6
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• pp.726-734
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• 2018

The total number of Sea Area Utilization Consultation in the environment management sea areas reviewed from 2015 to 2017 were 60. The number of development projects in the environment conservation sea areas decreased steadily, but special management sea areas increased. Development types in environment management sea areas showed that artificial structure installation was the highest ratio, followed by fishery port development and construction of habor and coastal maintenance and sea water intake and draining. By comparing the trend of water quality changes using marine environment information system (MEIS) data in the environment management areas from 2006 to 2017, COD showed no significant changes but the environment conservation sea areas increased slightly, and the concentration of TN and TP decreased. Gwangyang and Masan bays in the special management sea areas and Gamak bay in the environment conservation sea areas displayed oxygen deficient mass in the summer. As the use of development projects of the environment management sea areas are performed continuously, an analysis of the status of sufficient water quality changes is necessary for environmental impact assessment (Sea Area Utilization Consultation) in the marine environment and should be evaluated mainly for management of contamination by diagnosing thoroughly water quality effects and the pollution of sediment. Especially, the water quality goal for the purpose of designation in each of the environment management sea areas is set clearly, connection with pollution source control and the total pollution load management system (TPLMS) should be proposed and measured to reduce the amount of contaminated water.

• Journal of the Korean Ceramic Society
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• v.39 no.8
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• pp.801-806
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• 2002

The decomposition and/or conversion of carbon dioxide to carbon have been studied using oxygen-deficient ferrites for the reduction of $CO_2$ emission to the atmosphere. In this work, the homogeneous precipitation method using urea decomposition was employed to induce in situ precipitation of Ni ferrite($Ni_{0.4}Fe_{2.6}O_4$) on the porous ceramic fiber support (50 mm diameter${\times}$10 mm thickness). Effects of ferrite loading conditions on the CO2 decomposition efficiency were discussed in this paper. Removal of residual chloride ions and urea by solvent exchange from the porous media after ferrite deposition apparently helps to form spinel ferrite, but does not increase the efficiency of $CO_2$ decomposition. Porous ceramic fiber composites containing 20 wt% (1g) ferrite samples showed 100% efficiency for $CO_2$decomposition during the first three minutes, but the efficiency decreased rapidly after the elapsed time of ten minutes. The characteristic reduction time for the $CO_2$ decomposition efficiency was estimated as about 3∼7 min.

• Journal of the Korean Ceramic Society
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• v.39 no.7
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• pp.657-662
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• 2002

The reduced ferrites, reduced NiF $e_2$ $O_4$ and CuF $e_2$ $O_4$, by C $H_4$ were applied to $CO_2$ decomposition to avoid the greenhouse effects. At the reduction reaction above $700^{\circ}C$, $H_2$ and CO were generated by partial oxidation of C $H_4$ After the reduction reaction up to 80$0^{\circ}C$, the spinel structure ferrites changed to mixture of the oxygen deficient iron oxide (Fe $O_{(1-{\delta})}$(0$\leq$$\delta$$\leq$1)) and the metallic Ni or Cu. The rate and quantity of $CO_2$ decomposition with reduced CuF $e_2$ $O_4$ were larger than those with reduced NiFe $O_4$. The $CO_2$ gas was decomposed by oxidation of the oxygen deficient iron oxide. The metallic Cu and Ni were not oxidized and remained in a metallic state up to 80$0^{\circ}C$. The $CO_2$ decomposition reaction with the reduced ferrite by C $H_4$ gas is excellent process preparing useful gas such as $H_2$and CO and decomposing $CO_2$ gas.

• Korean Journal of Materials Research
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• v.4 no.5
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• pp.550-555
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• 1994

The effects of RTA treatment on the leakage current have been studied for tantalum pentoxide( $Ta_2O_5$) films deposited by PECVD on P-type(100) Si substrate using $TaCl_5$(99.99%) and $N_2O$(99.99%) gaseous mixture. The refractive index increased with increasing the deposition temperature and the maximum deposition rate was obtained at $500^{\circ}C$. The Ta-0 bond peak intensity of as-deposited $Ta_2O_5$ increased with increasing the deposition temperature through FT-IR analysis and the leakage current value was decreased with increasing the deposition temperature. The small leakage current value obtained after RTA treatment of as-deposited $Ta_2O_5$ was found to be due to the reduction of 0-deficient structure in the film. The increases of the oxygen coacentration and the Ta-0 bond peak intensity in the film after RTA treatment were measured by AES and FT-IR analyses.

• 한국해양학회지
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• v.27 no.4
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• pp.303-310
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• 1992

Studies on the distribution of nitrogenous compounds, and respiratory oxygen consumption rate were carried out in Masan Bay, Korea where large amount of industrial and domestic wastewaters are discharged. In August 1986 the surface layer was significantly influenced by freshwater input. Below the seasonal pycnocline, an oxygen-deficient condition developed in a large area of Masan Bay. Concentrations of DIN, DON and PN were 735.6, 1261.8 and 48.5 umol/l at the head, and 79.1, 73.0 and 39.5 umol/l at the mouth of the inner Masan Bay, respectively. Phytoplankton carbon production was 2,695 mgC/m$^2$/day at the mouth of inner Masan Bay. Dissolved oxygen contents were lower than 1 ml/l from 3 m depth in inner Masan Bay and from 10 m depth in the outer Masan Bay. The high concentration of ammonium and phosphate in the lower layer suggests the active degradation of organic materials in the bottom waters and leaching from sediments. The ERS activity was 232.1 ul O$_2$/l/h in the surface waters of the innermost part of Masan Bay and respiratory oxygen consumption is likely to proceed at a rate of 442 ml O$_2$/m$^2$/day in the bottom waters of this bay. Nitrate removal rate was estimated to be 0.25 umol/l/day via denitrification in the bottom waters of the Masan Waterway. It is estimated from the ETS activity that, at the mouth of inner Masan Bay, 9.3-10.5% of carbon fixed in the upper layer was decomposed below the themocline.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.05a
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• pp.134-136
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• 1993

Using the extended H$\ddot{u}$ckel molecular orbital method in connection with the tight binding model, we have studied electronic structure and related properties of superconducting $YBa_2Cu_3O_{7-x}$ crystals in which O-atoms in regular sites were selectively replaced with F atoms. The calculations are based on the crystal structure of Y-Ba-Cu-O obtained by Beno et al.. We use atomic coordinates that refer to the unrelaxed Y-Ba-Cu-O system. In analogy to the isomerism problem with molecules, we discuss all possible combinations of F-substitutions in O-sites with one, two, and four F atoms. The calculations are carried out within charged clusters model for the analogues of the YBa-free copperoxide. Our results suggest that the electronic structure of the symmetrically F-substituted or F-added compound is closer to that of the oxygen-deficient superconducting compound than that obtained from unsymmetrical substitution. This applies in particular if O is replaced with in an O(1) site. This suggests that superconductivity is very sensitive to the oxygen content of the $CuO_2$ layers.

• KSBB Journal
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• v.10 no.1
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• pp.78-88
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• 1995

The encapsulatpd A. niger grew up inside the capsule and mycelia penetrated through the pore of the capsule membrane. The mycelia on the capsule wall became loose when the carbon source and oxygen were deficient in the medium. On the contrary, the production rate increased and mycelia made a lump tightly when the carbon source and oxygen were sufficient. Namely, number of proper capsule of unit volume in the medium was existed. The phenomenon which was swelled of capsule membrane in cultivation could prevented by adding CaCl2 into the medium. According to the time adding CaCl2 into the medium, the production rate of citric acid was influenced. In case of adding CaCl2 into the medium at 7th day cultivation, the production yield of citric acid was increased about 40 percent higher than that of adding CaCl2 initially. The production yield of citric acid using encapsulated A. niger of flask culture was influenced with oxygen supply. The production yield of citric acid ($\Delta$p/$\Delta$s) of the flask culture was increased 3.88 time by using T-flask instead of parafilm sealed flask. Therefore, the productivity and consumption rate concerning production which was taken carbon source were increased when oxygen supply was sufficient. The production of citric acid using encapsulated A. niger was increased average 30 percent higher than that of bead in between 6th and 13th day cultivation.

• Bulletin of the Korean Chemical Society
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• v.27 no.6
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• pp.853-856
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• 2006

Dion-Jacobson phases $CsCa_2Nb_2FeO_9$ and $CsCa_2Nb_2AlO_9$ were reinvestigated by the Rietveld analysis of powder X-ray diffraction (XRD) method, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). These nominal compounds, previously known as the oxygen-deficient layered perovskites with the sequences of $NbO_6-MO_4-NbO_6$ in tripled slab, in fact, were mixed phases of n = 3 Dion-Jacobson phases and impurities such as $Ca_2NbFeO_6$ and $Ca_3Al_2O_6$. The difference of morphology and chemical in-homogeneity between Dion-Jacobson phases and impurities could be clearly identified by scanning electron microscopy with energy-dispersive X-ray spectroscopy. The chemical composition of $CsCa_2Nb_2FeO_9$ was calculated into $Cs_{0.59}Ca_{2.64}Nb_{2.92}Fe_{0.81}$ in small agglomerate crystals and $Cs_{0.95}Ca_{1.97}Nb_{3.08}Fe_{0.15}$ in long plate-like crystals.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1679-1683
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• 2013

Intergrowth perovskite type complex oxides $La_{0.8}Ln_{0.2}Sr_2MnCrO_{7-{\delta}}$ (Ln=La, Nd, Gd, and Dy) have been synthesized by sol-gel method. Rietveld profile analysis shows that the phases crystallize with tetragonal unit cell in the space group I4/mmm. The unit cell parameters a and c decrease with decreasing effective ionic radius of the lanthanide ion. The magnetic studies suggest that the ferromagnetic interactions are dominant due to $Mn^{3+}$-O-$Mn^{4+}$ and $Mn^{3+}$-O-$Cr^{3+}$ double exchange interactions. Both Weiss constant (${\theta}$) and Curie temperature ($T_C$) increase with decreasing ionic radius of lanthanide ion. It was found that the transport mechanism is dominated by Mott's variable range hopping (VRH) model with an increase of Mott localization energy.

• Journal of Ocean Engineering and Technology
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• v.22 no.5
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• pp.61-68
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• 2008

In Jinhae-Masan bay, a typical semi-dosed bay in Korea, the water quality is severely deteriorated because of the dosed topographic character and the inflow of nutrients from the land. There have been attempts to apply a water quality model dealing with the entrophication phenomenon and the oxygen-deficient mass in the bay in summer, but there have been few examples of models that have considered the phenomenon of stratification in the proper order, and then it is performed the model of water quality. Therefore, this study collected and analyzed the pre-observed water temperature data from Jinhae-Masan bay in summer and then constructed a density model using the topographic heat accumulation effect and inflow from the river to examine the temperature stratification. The simulation results show that this model could demonstrate the temperature stratification in the Jinhae-Masan bay very well.