• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.10 no.4
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• pp.273-280
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• 2012

The electrochemical behaviors of 10 g-scale fresh and oxidized Zircaloy-4 cladding hulls were examined in $500^{\circ}C$ LiCl-KCl molten salts to confirm the feasibility of the electrorefining process for the treatment of hull wastes. In the results of measuring the potential-current response using a stainless steel basket filled with oxidized Zircaloy-4 hull specimens, the oxidation peak of Zr appears to be at -0.7 to -0.8 V vs. Ag/AgCl, which is similar to that of fresh Zircaloy-4 hulls, while the oxidation current is found to be much smaller than that of fresh Zircaloy-4 hulls. These results are congruent with the outcome of current-time curves at -0.78 V and of measuring the change in the average weight and thickness after the electrochemical dissolution process. Although the oxide layer on the surface affects the uniformity and rate of dissolution by decreasing the conductivity of Zircaloy-4 hulls, electrochemical dissolution is considered to occur owing to the defect of the surface and phase properties of the Zr oxide layer.

• Journal of the Mineralogical Society of Korea
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• v.18 no.1
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• pp.11-17
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• 2005

Na-A zeolite were synthesized from melting slag of the incinerated ash by the alkaline activation processes. The experiments were performed in stainless steel vessels, with continuous stirring during the reaction periods. The silica-rich solution, a starting material, which was the waste of crystal growth factory, contains 5.7 wt% SiO₂ and 3.2 wt% Na₂O. And NaAlO₂ was made by the reaction of aluminium dross and NaOH solution and its molar ratios were Na₂O/Al₂O₃= 1.2 and H₂O/Na₂O=9. During the residence time of 7∼8 h at 80℃, the mixing of the silica-rich solution, NaAlO₂ and melting slag yields the production of homogeneous Na-A zeolite. The optimal reactant composition in molar ratio of Na₂O:Al₂O₃:SiO₂ was 1.3∼l.4 : 0.8∼0.9 : 2 and mixing ratio of solution and slag was 1/7∼10 (g/cc). Synthesized Na-A zeolite has cubic form uniformly and its size ranges about 1 ㎛. Ca/sup 2+/ ion exchange capacity of the Na-A was about 180∼210 meq/100g, corresponding approximately 80% to the commercial detergent builder.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.2
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• pp.224-234
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• 1997

In order to make high purity materials including low contents of interstitial impurities, 70 ㎾ electron beam melter was manufactured. The sponge Ti and Ti-6Al-4V alloy were required and melted by electron beam melter. Based on the experimental results of sponge Ti refining by electron beam melting, the purity of Ti was increased for 180 seconds but thereafter did not significantly vary. In addition, it was found that with number of melting, the purity of Ti did and vary but the yield of Ti was decreased. As a results of Ti refining, high purity Ti of 3N (99.9 wt%) could be obtained including interstitial impurities with total contents of which were maximum 900 ppm. From the experimental results of Ti-6Al-4V alloy electron beam melting, the amounts of Al loss could be estimated through thermodynamic data calculated from the regular solution model and the model of solute removal kinetics and the alloy composition calculated from the models was in accord with the experimental composition of the alloy, It took 10 minutes to make Ti-29Al-4V alloy calculated from the model into Ti-6Al-4V alloy and the composition of Ti-6Al-4V alloy was very homogeneous.

• Economic and Environmental Geology
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• v.41 no.6
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• pp.731-746
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• 2008

Most multiphase flow simulators following fractional flow approach assume incompressibility of fluid and matrix or consider only two phase flow (water and air, water and NAPL). However, in this study, mathematical governing equations were developed for fully compressible three-phase flow using fractional flow based approach. Also, fully compressible multiphase flow simulator (CMPS) considering compressibilities of matrix and fluid was developed using the mathematical governing equations. In order to verify CMPS, the CMPS were compared with analytical solution and the existing multiphase flow simulator, MPS, which had been developed for simulating incompressible multiphase flow (Suk and Yeh 2007; Suk and Yeh 2008). According to the results, solutions of CMPS and MPS and analytical solutions are well matched each other. Thus, it is found that CMPS has the capability of simulating compressible three phase flow phenomena assuming compressibilities of fluids and matrix.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.682-689
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• 1999

In this study, binary PA 6,6/EPM(or EPM-g-MA) blends and ternary PA 6,6/EPM/EPM-g-MA blends were fabricated according to the variation in elastomer content and composition ratio of blend, and mixing temperature and rate so as to investigate the degree of influence of elastomer content and average particle size, morphology, and distribution of dispersed elastomer on properties of blends. As results, under the constant mixing rate(250 rpm) and different five section temperature profiles(270-265-265-255-$255^{\circ}C$) in extruder, high notched Izod impact strength was the property of PA 6,6/EPM-g-MA(70/30) blend among binary blends. Notched Izod impact strength of this blend was 25 times improvement compared with that of polyamide 6,6. In addition, elastomer average particle size of ternary PA 6,6/EPM/EPM-g-MA(70/15/15) blend was $0.56{\mu}m$, which was fine distribution, and notched Izod impact strength of that blend was the highest of all blends prepared with the variation in elastomer content. But the properties of this ternary blend were decreased remarkably at the diverse mixing temperatures and mixing rates.

• The Journal of the Petrological Society of Korea
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• v.18 no.4
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• pp.337-348
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• 2009

Clear and homogeneous glass inclusions are well preserved at the rim of the quartz phenocrysts of tuff from Sunshin epithermal Au deposit, Haenam, although the host rocks experienced extensive silicification and argillic alteration. Glass inclusion vary in size from $5\;{\mu}m$ to larger than $200\;{\mu}m$ consisting of glass(60~80 vol%) + vapor bubble(15~30 vol%) $\pm$ daughter crystals(<10 vol%). Most of glass inclusions are cubic to rectangular in shape, indicating that the host quartz grew in the stability field of $\beta$-quartz. All the glass inclusions appear to be primary. Glass inclusions are composed of highly evolved high-K calc-alkaline rhyolites, which can represent the final liquidus phase of the magma system. The $Au_2O_3$ concentration (<0.30 wt%) is trivial in the glass, indicating there was no enrichment in the final residual melt. Textural characteristics suggest that magma was water-saturated shortly before or during the eruption. $H_2O$ content of the glass (ca. 2-4 wt%) suggests a water saturation pressure($P_{H2O}$) of about 300-900 bars. This pressure implies a minimum depth of 0.8-2.5 km for the magma chamber.

• The Journal of the Petrological Society of Korea
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• v.24 no.1
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• pp.25-54
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• 2015

Syenite is not a common rock, unlike granitic rocks formed the major component of the continental crust. The aim of this study is to decipher the occurrences and detailed descriptive characteristics of the syenite distributed in Sancheong area, and to investigate the petrogenesis of the syenitic magma based on geochemical study. The dominant minerals in syenite are alkali feldspar (usually orthoclase and rarely microcline), plagioclase, amphibole, biotite, and quartz. Syenites are found in a wide variety of colors. The anhedral hornblende and biotite filling the boundary of feldspar and quartz indicate that the hydrous minerals were crystallized lately, and that water was insufficient at the beginning of crystallization in magma. According to the analysis of mineral composition, amphibole in syenite is mostly ferro-edenite, and the pressure is calculated as 3.3~4.9 kb with 11.9~17.3 km of emplacement depth. Biotite and pyroxene are plotted in the region of annite and hedenbergite, respectively. Based on petrochemical studies of major elements, syenite belongs to alkaline series, metaluminous, and I-type. On the other hand, the variation patterns of trace and rare earth elements of syenite differ from the patterns of diorite and granite. In the geochemical characteristics, syenite is different from gabbro-diorite spatially adjacent to syenite, as well as granite. These results suggest that each rock has been generated from the different sources of magma. Additionally, based on the experimental data, the syenitic magma can be formed (1) by the partial melting at a high pressure and dry system, (2) when the initial crystallization minerals to be residue with migration of the residual melts separated from the ascending cotectic magma (3) when fluorine compositions to be plentiful in the protolith and/or at depth of the magma. Based on the petrographic characteristics of the syenite, Sancheong syenitic magma may have been formed by partial melting in a dry system.

• Economic and Environmental Geology
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• v.28 no.6
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• pp.623-633
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• 1995

The Beonam deposits which is located in south-western part of Sobaeksan massif are emplaced along $N20{\sim}30^{\circ}E$ trending fissures in Precambrian Sobaeksan gneiss complex. Surrounding granites are inferred to be differentiated and formed from calc-alkaline magma which was generated from remelting or partial melting of the crustral material having igneous composition. The Sr isotope data of ore minerals showing significantly low initial Sr value relative to those of surrounding granite batholiths suggest that the ore-bearing fluid formed the Beonam Au-Ag mine are isotopically distinct from those of the wall rocks, and it indicates that there is no evidence of genetic relationship between ore-bearing fluids and surrounding granites, although further study should be needed. The results of paragenetic studies suggest three stages of hydrothermal mineralization; stage I: base-metal sulfides stage, stage II: late base-metal sulfides, electrum and silver-bearing sulfosalts stage, stage III: minor silverbearing minerals, barren quartz and carbonates stage. The temperature, salinity and pressure of the Beonam deposits estimated from mineral assemblage, chemical composition, fluid inclusion and sulfur isotope geothermometry are as follows; stage I: $200{\sim}315^{\circ}C$, 3.5~6.5 NaCl eq. wt%, 0.28~0.61 Kbar, stage II: $150{\sim}235^{\circ}C$, 4.5~7.4 NaCl eq. wt%, 0.11~0.15 Kbar. The estimated oxygen and sulfur fugacity during first stage mineralization, based on phase relation of associated minerals, range from $10^{35.1}{\sim}10^{-39.7}$ atm. and $10^{-11.0}{\sim}10^{-13.4}$ atm., respectively. All these evidences suggest that the Beonam deposits are polymetallic meso-epithermal ore deposits.

• Korean Chemical Engineering Research
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• v.58 no.3
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• pp.369-380
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• 2020

Most mono-crystalline silicon ingots are manufactured by the Czochralski (Cz) process. But If there are oxygen impurities, These Si-ingot tends to show low-efficiency when it is processed to be solar cell substrate. For making single-crystal Si- ingot, We need Czochralski (Cz) process which melts molten Si and then crystallizing it with seed of single-crystal Si. For melts poly Si-chunk and forming of single-crystalline Si-ingot, the heat transfer plays a main role in the structure of Cz-process. In this study to obtain high-quality Si ingot, the Cz-process was modified with the process design. The crystal growth simulation was employed with pulling rate and rotation speed optimization. Studies for modified Cz-process and the corresponding results have been discussed. The results revealed that using crystal growth simulation, we optimized the oxygen concentration of single crystal silicon by the optimal design of the pulling rate, rotation speed and melt charge level of Cz-process.

• Nuclear Engineering and Technology
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• v.27 no.3
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• pp.301-316
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• 1995

experimental and computational studies ore carried out to investigate the natural convection of the single phase flow in a tank with a heated horizontal plate facing downward. This is a simplified model for investigations of the influence of a core melt at the bottom of a reactor vessel on the thermal hydraulic behavior in a oater filled cavity surrounding the vessel. In this case the vessel is simulated by a hexahedron insulated box with a heated plate Horizontally mounted at the bottom of the box. The box with the heated plate is installed in a water filled hexahedron tank. Coolers are immersed in the U-type water volume between the box and the tank. Although the multicomponent flows exist more probably below the heated plate in reality, present study concentrates on the single phase flow in a first step prior to investigating the complicated multicomponent thermal hydraulic phenomena. In the present study, in order to get a better understanding for the natural convection characteristics below the heated plate, the velocity and temperature are measured by LDA(Laser Doppler Anemometry) and thermocouples, respectively. And How fields are visualized by taking pictures of the How region with suspended particles. The results show the occurrence of a very effective circulation of the fluid in the whole How area as the heater and coolers are put into operation. In the remote region below the heated plate the new is nearly stagnant, and a remarkable temperature stratification can be observed with very thin thermal boundary. Analytical predictions using the FLUTAN code show a reasonable matching of the measured velocity fields.