• Proceedings of the Korean Institute of Surface Engineering Conference
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• 한국표면공학회 2001년도 추계학술발표회 초록집
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• pp.56-56
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• 2001

Ni-W alloy deposit is one of the best alternatives to hard chromium plating because of its good mechanical properties (high hardness, high strength, and good wear resistance). Ni-W alloy is deposited from weakly acidic or alkaline electrolytic bath with nickel sulfate, sodium tungstate or APT, and some kinds of organic hydroxy-acid complex and ammonia salts. W content of the deposit can be changed from 0 to 5Owt% and the coating with high W content is more attracted. But, meanwhile, the deposited layers are always found high internal stress, which cause them to become brittle and to bond insufficiently with the substrate. On the second hand, as the W content is incresed, the current efficiency reduced, which results in large quantities of hydrogen evolution and then produces bubbles on surface and pitting appearance In this paper, the influence of some additives on Ni-W alloy electroplating was investigated by means of compositional analysis and SEM. The initial results showed that 2-butyne-1,4-diol was the best brightener for Ni-W plating process. It could brighten and level deposit, but decreased the cathodic current efficiency. Its optimum concentration range is from O.lgjL to 0.5gjL. Besides, three kinds of additives including 2-butyne-1,4-diol were examined with Dagguchi method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 1993년도 추계학술대회 논문집
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• pp.161-165
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• 1993

최근 산업의 발달과 함께 제품의 고정도화,다양화,생산성 향상등의 요구에 의해 연삭가공에 있어서도 고능률.고정도가공이 주목되고 있다. 특히 반도체산업,광산업 등에 넓게 응용되고 있는 광학소자 가공에서는 가공정도와 가공능률이 동시에 달성되는 것에 대한 요구가 많지만, 이러한 광학소자의 가공에 있어서 기존의 연마방법은 가공정도와 가공능률에 한계가 있었다. 그런데 연삭가공에서 고능률,고정도가공의 한가지 방법으로 "전해 인프로세스드레싱(Electrolytic In-Process Dressing;ELID)연삭법"이 개발되어 고강도 메탈본드숫돌에 의한 초경합금,세라믹재료등의 경취성재료를 고품위 가공하고 있다. ELID연석법이란 숫돌의 다이아몬드나 cBN등의 연삭입자를 결합하고 있는 금속결합재를 전기분해에 의해 적당량 제거하여 일반적인 연삭과 같이 연삭입자를 연속적으로 돌출시켜 가공이 유지되도록 하는 연삭방법이다. 본 연구는 ELID연삭기술을 이용하여 원통연삭에서 철갈재료 및 세라믹재료의 고능률.고정도 가공특성을 살펴보았다. 원통연삭에서의 주철파이바본드숫돌 및 코발트본드숫돌에 의한 ELID연삭과 비트리파이드본드숫돌에 의한 일반연삭과의 고능률 가공특성을 비교하였다.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• 제5권2호
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• pp.73-82
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• 1996

A simtered carbide roller mold for reflector which is used for coverof automobile lamp and beacon plate of highway has been developed. The geometry of sintered carbide roller mold has been determined from the analysis of reflector geometry. An acute angle diamond wheel and dressing system also has been designed and developed to manufacture the sintered carbide roller mold.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 한국공작기계학회 1996년도 춘계학술대회 논문집
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• pp.170-176
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• 1996

A Sintered carbide roller mold for reflectors which is used for cover of automobile lamp and beacon plate of highway has been developed. The geometry of sintered carbide roller mold has been determined from the analysis of reflector geometry. An acute angle diamond wheel and dressing system also has been designed and developed to manufacture the sintered carbide roller mold.

• Journal of the Korean Vacuum Society
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• 제12권S1호
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• pp.21-27
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• 2003

Micro-arc discharge oxidation (MDO) is a cost-effective plasma electrolytic process which can be used to improve the wear and corrosion resistance of Al-alloy parts by forming a alumina coating on the component surface. However, the MDO coated Al-alloy components often exhibit relatively high friction coefficients and low wear resistance fitted with many counterface materials, additionally, the pitting corrosion for the MDO coated AI-alloy components, especially for a thinner alumina coating, often occurs in atmosphere circumstance due to the porous alumina coats. Therefore, a duplex treatment, combining a MDO coated ahumina thin layer with a TiN coating, prepared by magnetron sputtering (MS), has been investigated. The Vicker's microhardness, pin-on-disc, electrochemical measurement, salt spray, XRD and SEM tests were used to characterize and analyze the treated samples. The work demonstrates that the MDO/MS coated samples have a combination of a very low friction coefficient and good wear resistance as well as corrosion since the micro-holes on alumina coating are partly or fully covered by TiN material.

• Proceedings of the KAIS Fall Conference
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• 한국산학기술학회 2001년도 춘계학술대회 발표논문집
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• pp.290-291
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• 2001

The relationship between velocity, viscosity, diffusion coefficient, mass transfer coefficient and characteristic length and mass transfer data can be correlated by dimensionless relationship in electrolytic process. The performance of dyestuff removal was decreased as the flow rate of electrolyte was increased. It was due to the effect of retention time decreasing was superior to that of turbulent inlet mixing. Sh/Sc$\^$1/3/ vs Re plot for Al flat electrode did not showed the general tendency of the relationship between Sh/Sc$\^$1/3/ and Re. It can be thought that flow rate was not sufficiently high to increase the effect of mixing.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• 제10권4호
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• pp.229-236
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• 2012

A molten salt technology using $Li_2O$-LiCl has been extensively investigated to recover uranium metal from spent fuels in the field of nuclear energy. In the reduction process, it is an important point to maintain the concentration of $Li_2O$. $ZrO_2$ is inevitably contained in the spent fuels because Zr is one of the main components of fuel rod hulls. Therefore, the fate of $ZrO_2$ in $Li_2O$-LiCl molten salt has been investigated. It was found that $Li_2ZrO_3$ and $Li_4ZrO_4$ were formed chemically and electrochemically and they were not reduced to Zr. The recycling of $Li_2O$ is the key mechanism ruling the total reaction in the electrolytic reduction process. However, $ZrO_2$ will have a role as a $Li_2O$ sink.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 한국방사성폐기물학회 2017년도 추계학술논문요약집
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• pp.73-73
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• 2017

Pyroprocessing at KAERI (Korea Atomic Energy Research Institute) consists of pretreatment, electroreduction, electrorefining and electrowinning. SFR (Sodium Fast Reactor) fuel is prepared from the electrowinning process which is composed of LCC (Liquid Cadmium Process) and Cd distillation et al. LCC is an electrochemical process to obtain actinides from spent fuel. In order to recover actinides inert anodes such as carbon material are used, where chlorine gas ($Cl_2$) evolves on the surface of the carbon material. And, stainless steel (SUS) crucible should be installed in large-scale electrowinning system. Therefore, the effect of chlorine on the SUS material needs to be studied. LiCl-KCl-$UCl_3$-$NdCl_3$-$CeCl_3$-$LaCl_3$-$YCl_3$ salt was contained in 2 kinds of electrolytic crucible having an inner diameter of 5cm, made of an insulated alumina and an SUS, respectively. And, three kinds of electrodes such as cathode, anode, reference were used for the electrochemical experiments. Both solid tungsten (W) and LCC were used as cathodes. Cd of 45 g as the cathode material was contained in alumina crucibles for the deposition experiments, where the crucible has an inner diameter of 3 cm. Glassy carbon rod with the diameter of 0.3 cm was employed as an anode, where shroud was not used for the anode. A pyrex tube containing LiCl-KCl-1mol% AgCl and silver (Ag) wire having a diameter of 0.1cm was used as a reference electrode. Electrodeposition experiments were conducted at $500^{\circ}C$ at the current densities of $50{\sim}100mA/cm^2$. In conclusion, Fe ions were produced in the salt during the electrodeposition by the reaction of chlorine evolved from the anode and Fe of the SUS crucible and thereby LCC system using SUS crucible showed very low current efficiencies compared with the system using the insulated alumina crucible. Anode shroud needs to be installed around the glassy carbon not to influence surrounding SUS material.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• 제7권2호
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• pp.125-131
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• 2009

An electrolytic system (zinc anode-gallium cathode) was setup to evaluate the performance of several stirrers prepared for this study, where stirrers have been used to prevent uranium from forming dendrite on the cathode in pyrochemical process. In the case of no-stirring condition, zinc dendrites began to grow on the gallium surface in 1 hour and some dendrite grew out of the cathode crucible around 6 hours. When a rectangular stirrer or a tilt stirrer was rotated, at 40${\sim}$150 rpm, to mix the liquid gallium cathode, dendritic growth of zinc metal was prevented irrespective of revolution speed, but some of the deposits overflowed out of the cathode crucible owing to the large centrifugal forces at 150 rpm. The harrow stirrer did not nearly retard the dendrite growth at 40 rpm, but the dendrite growth was retarded at higher than 100 rpm and the zinc deposits also did not overflow at 150 rpm. Pounder could also prevent the dendrite growth to some extent but it had some difficulties in operation compared with other types of stirrers.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• 제1권1호
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• pp.11-23
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• 2003

A study on the electrolytic dissolution of SUS-304 and Inconel-600 specimen was carried out in neutral salt electrolyte to evaluate the applicability of electrochemical decontamination process for recycle or self disposal with authorization of large amount of metallic wastes contaminated with uranium compounds generated by dismantling a retired uranium conversion plant in Korea. Although the best electrolytic dissolution performance for the specimens was observed in a Na2s04 electrolyte, a NaNO$_3$ neutral salt electrolyte, in which about 30% for SUS-304 and the same for Inconel-600 in the weight loss was shown in comparison with that in a Na$_2$SO$_4$ solution, was selected as an electrolyte for the electrochemical decontamination of metallic wastes with the consideration on the surface of system components contacted with nitric acid and the compatibility with lagoon wastes generated during the facility operation. The effects of current density, electrolytic dissolution time, and concentration of NaNO$_3$ on the electrolytic dissolution of the specimens were investigated. On the basis of the results obtained through the basic inactive experiments, electrochemical decontamination tests using the specimens contaminated with uranium compounds such as UO$_2$, AUC (ammonium uranyl carbonate) and ADU (ammonium diuranate) taken from an uranium conversion facility were performed in 1M NaNO$_3$ solution with the current density or In mA/$\textrm{cm}^2$. it was verified that the electrochemical decontamination of the metallic wastes contaminated uranium compounds was quite successful in a NaNO$_3$ neutral salt electrolyte by reducing $\alpha$ and $\beta$ radioactivities below the level of self disposal within 10 minutes regardless of the type of contaminants and the degree of contamination.