• Natural Product Sciences
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• v.5 no.4
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• pp.165-171
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• 1999

Since reactive oxygen species (ROS) play an important role in carcinogenesis and other several human diseases, antioxidants present in consumable fruits, vegetables, and beverages have received considerable attention as cancer chemopreventive agents. Thus, in order to identify antioxidants in plant extracts, potential activity was assessed by determining with inhibition of a xanthine/xanthine oxidase assay system. Approximately 170 plant extracts of Korean herbal medicines were primarily evaluated for the potential of antioxidant activity. As a result, 13 plant extracts were found to be active $(IC_{50}$<$100\;{\mu}g/ml)$. Especially, Juncus effusus, Selaginella tamariscina, Pueraria thunbergiana and Sedum albroseum showed strong inhibitory activity in this process. Further studies for the identification of active principles from these active lead plant extracts might be warranted.

• Journal of Welding and Joining
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• v.31 no.1
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• pp.38-42
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• 2013

In the welding of aluminum, it is important to provide a stable gas shield to exclude not only oxygen, but any sources of hydrogen, from the arc environment. Common sources of hydrogen are humidity in the air around the arc, moisture in the shielding gas, and residual lubricants on the surface of the welding consumable. Since molten aluminum can absorb seventy times more hydrogen than solid aluminum, as the aluminum cools, it releases hydrogen that then becomes trapped in the form of hydrogen bubbles in the solidifying metal.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.6
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• pp.860-864
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• 2012

The contact tip is higher the wear of resistance and the longer life are demanded to GMA welding process. In this study, four different contact tips with three different compositions by two wires were evaluated their wear resistance by measuring in every one hour the area of enlarged hole at the exit side during actual wleding. Experimental results clearly showed that the Cr-containing tips strengthened by precipitation hardening have much better resistance to wear than those made by work hardening. In addition, flux cored wire is excellent abrasion resistance test results showed. Based on these results, the domestic industry, the life of the contact tip to know will be used as basic data.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1271-1272
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• 2006

CMP(chemical mechanical polishing) process has been attracted as an essential technology of multi-level interconnection. However, the COO(cost of ownership) is very high, because of high consumable cost. Especially, among the consumables, slurry dominates more than 40%. So, we focused how to reduce the consumption of raw slurry. In this paper, $ZrO_2$, $CeO_2$, and $MnO_2$ abrasives were added de-ionized water (DIW) and pH control as a function of KOH contents. We have investigate the possibility of new abrasive for the oxide CMP application.

• International Journal of Korean Welding Society
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• v.2 no.1
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• pp.52-56
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• 2002

This report was prepared to give informations on a proper way to develop new consumables for the steels with improved weldability. Traditionally, hydrogen control has been pursued mainly for suppressing the HICC in HAZ but it also has contributed to HICC in weld metal. Facing the limitations in reducing the hydrogen content, it is now important to consider the microstructural control approach in order to improve the HICC resistance of weld metal . It has been shown that changes in alloy design, and hence composition and microstructure, was quite effective in producing high strength weld metal with improved resistance to cold cracking. Besides the economic test methods for evaluating susceptibility of multipass weld metal is essential to promote the development of welding consumables.

• Journal of the Korean institute of surface engineering
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• v.30 no.3
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• pp.159-166
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• 1997

The metalliding technique was adopted to obtain the diffusion coating of zirconium on AISI 304 Stainless Steel in molten mixed chlorides (32.9wt.%LICl-34.8wt.%NaCl-32.3wt.%). Experiments were carried out in argon gas atmosphere. The electrolytic cell was consisted of a AISI 304 Stainless steel cathode and a consumable zirconium anode. The quality of deposit was analysed by SEM, Optical Microscope, EDS, and also examined by the Micro-Vickers hardness and corrosion tests. Interface of deposit layer was identified as zirconium-iron alloy layer caused by diffusion process at elevated temperatures. The optimum condition for the metalliding was found to be the bath temperature of $550^{\circ}C$, the concentration of $K_2ZrF_6$ ,5wt.%, cathodic current derrent density of 7.0 to 10.0mA/$\textrm{cm}^2$ , and anodic current density of 2.0mA/$\textrm{cm}^2$.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.83-84
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• 2006

Chemical mechanical polishing (CMP) process has been attracted as an essential technology of multi-level interconnection. However, the COO (cost of ownership) is very high, because of high consumable cost. Especially, among the consumables, slurry dominates more than 40 %. So, we focused how to reduce the consumption of raw slurry. In this paper, $MnO_2$ abrasives were added de-ionized water (DIW) and pH control as a function of KOH contents. Also, the addition effects of $MnO_2$ abrasives and the diluted silica slurry (DSS) on CMP performances were evaluated. Finally, we have investigated the possibility of new abrasive for the oxide CMP application.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.1
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• pp.97-104
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• 2005

Considered is the concurrent spare part(CSP) requirements problem of new equipment system. In the considered system, when a part fails, the part cannot be repaired and should be replaced. In addition, cannibalization is allowed. It is assumed that the failure of a part follows a Poisson process. The operational availability concept in CSP is defined, and a formula is derived to calculate the operational availability using expected machine operating time during CSP period. The problem is formulated as the operational availability maximization problem with available budget constraint and a heuristic solution search procedure is developed. An illustrative example is shown to explain the solution procedure.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1731-1732
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• 2006

CMP(chemical mechanical polishing) process has been attracted as an essential technology of multi-level interconnection. However, the COO(cost of ownership) is very high, because of high consumable cost. Especially, among the consumables, slurry dominates more than 40 %. So, we focused how to reduce the consumption of raw slurry. In this paper, $ZrO_2$, $CeO_2$, and $MnO_2$ abrasives were added de-ionized water (DIW) and pH control as a function of KOH contents. We have investigate the possibility of new abrasive for the oxide CMP application.

• Journal of the Korean institute of surface engineering
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• v.26 no.4
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• pp.183-191
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• 1993

Diffusion coating(metalliding) of aluminium on steel from molten fluorides(29.2wt.% LiF-11.7wt.% NaF-59.1wt.% KF, FLINAK) was studied. The electrolytic cell consists of a steel cathode and a consumable aluminium anode. Effects of manganese on the aluminium deposition were also investigated. The quality of the deposit was analyzed by SEM, OM, EPMA, EDXA, and also examined by means of Micro-Vickers hardness and corrosion tests. Deposit layer was identified as an aluminium-rich iron alloy caused by diffusion process. The optimum condition for the metalliding was found to be the current density, 50 to $150mA/\textrm{cm}^2$, the bath tem-perature, $57.5^{\circ}C$, and the amount of AlF3, 10wt.%. Addition of manganese fluoride (up to 5wt.%) as a co-de-posit element improved significantly the quality of the deposit layer.