• Journal of Korean Society of Environmental Engineers
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• v.35 no.1
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• pp.31-37
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• 2013

To acquire enhanced adsorption capacity for especially targeted VOCs, activated carbon fiber of which surface area was $1,100m^2/g$ was selected and active metals were loaded. After screening study, Cr and Cu were selected as a base metal for improving adsorption capacity of activated carbon fiber. For acquiring better performance, metal loading, loading temperature, loading hours and kinds of loaded metals were changed as preparing variables. Properties measurement and adsorption capacity evaluation were performed. We found that the best conditions for metal loading were 5 hours loading at $100^{\circ}C$ and the adsorption capacity was enhanced almost double. Also we confirmed that more than 0.5 seconds contact time is needed for best adsorbate diffusion and adsorption over activated carbon fiber.

• Journal of Environmental Health Sciences
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• v.19 no.2
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• pp.46-54
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• 1993

This study was carried out on the stabilized/solidified treatment for the reducing leachability of hazardous heavy metals copper, lead, chromium and cadmium in the hazardous sludge which treated to be unleached heavy metals by sodium diethyl dithiocarbamate. Cement matrix was analyzed for the leachability of 24 hrs and dynamic leaching test, structure and the optimum condition for the stabilization and solidification of the hazardous sludge. In 28 days of curing time the unconfined compressive strength was 21.5 kg/cm$^2$ at the ratio of portland cement (0.5)+fly ash (0.25) and 23.5 kg/cmz at the ratio of portland cement (0.5)+fly ash (0.25) + cake (0.25). High concentration of Pb, Cr and Cd in the sea water and Cu in the distilled water were leached at the dynamic leaching test. The concentration of leaching heavy metals for specimens which were tested 24 hrs were found low leachability with decreasing pH of leachant. According to dynamic leaching test, the low level of copper, lead, cadmium and chromium were leached in the cement matrix with sodium diethyl dithiocarbamate. But the effective diffusion coefficient of unleached cement matrix which was treated sodium diethyl dithiocarbamate was decreased above 2 times than that of cement matrix. The relation of leachant renewal period (Y) and cumulative fraction ion leached (X) was the following regression equations. Solidification with unleached agent. Y$_{Cu}$ = 1413752X + 247, Y$_{Pb}$ = 223501IX + 214, Y$_{Cr}$ = 8310601X - 472, Y$_{Cd}$ = 168787X + 1061 The structure of' solidified matrix with X-ray diffraction analysis was composed more Ca(OH)$_2$, Si, Mg(OH)$_2$ and Al in the unleached cement matrix than those in cement matrix.

• Proceedings of the KWS Conference
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• 1996.05a
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• pp.186-189
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• 1996

A study was made to examine the characteristics of base metal and stress relief cracking(SRC) of heat affected zone(HAZ) for HY-100 and Cu-bearing HSLA-100 steels. The Gleeble thermal/mechanical simulator was used to simulate the SRC/HAZ. The details of mechanical properties of base plate and SRC tested specimens were studied. The specimens were aged at $650^{\circ}C$ for HSLA-100 steel and at 66$0^{\circ}C$ for HY-100 steel and thermal cycled from 135$0^{\circ}C$ In $25^{\circ}C$ with a cooling time of $\Delta$ $t_{800^{\circ}50}$ $0^{\circ}C$/=21sec. corresponds to the heat input of 30kJ/cm. The thermal cycled specimens were stressed to a predetermined level of 248~600MPa and then reheated to the stress relief temperatures of 570~62$0^{\circ}C$. The time to failure( $t_{f}$) at a given stress level was used as a measure of SRC susceptibility. The strength, elongation and impact toughness of base plate were greater in HSLA-100 steel than in HY-100 steel. The time to failure was decreased with increasing temperature and/or stress. HSLA-100 steel was more susceptible to stress relief cracking than HY-100 steel under same conditions. It is thought to be resulted from the precipitation of $\varepsilon$-Cu phase by dynamic self diffusion of solute atoms. Therefore, greater strain concentration at grain boundary of HSLA-100 steel results in the increased SRC susceptibility.y.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.3
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• pp.373-378
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• 2013

The speed change performance of transmissions has become a serious issue because of the increase in the inertia moment that has accompanied increases in engine output and transmission size. Therefore, it is necessary to develop better wear resistant friction materials. In this study, an appropriate sintered friction component for the synchronizer ring of a diesel manual transmission was developed, and its bonding characteristics were analyzed. That is, a process for bonding an Fe-based base material and Cu-based sintered friction material was developed. BSE and EDX analyses of this bonding layer were conducted, along with a shear strength test, to determine the bonding characteristics.

• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.416-423
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• 1996

Electrochemical reduction of thionyl chloride in 1.5 M $LiAlCl_4/SOCl_2$ electrolyte solution containing tetradentate Schiff base Co(II), Ni(II), Cu(II), and Mn(II) complexes has been investigated at the glassy carbon electrode. The catalyst molecules of transition metal(II) complexes were adsorbed on the electrode surface and reduced thionyl chloride resulting in a generation of oxidized catalyst molecules. There was an optimum concentration for each catalyst compound. The current density of $SOCl_2$ reduction was enhanced up to 150% at the catalyst contained electrolyte solution. The reduction currents of thionyl chloride were increased and the reduction potentials were shifted to the negative potential as scan rates became faster. The reduction of thionyl chloride was proceeded to diffusion controlled reaction.

• Journal of the Microelectronics and Packaging Society
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• v.13 no.4
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• pp.45-50
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• 2006

Copper via filling is the important factor in 3-D stacking interconnection of SiP (system in package). As the packaging density is getting higher, the size of via is getting smaller. When DC electroplating is applied, a defect-free hole cannot be obtained in a small size via hole. To prevent the defects in holes, pulse and pulse reverse current was applied in copper via filling. The holes, $20\and\;50{\mu}m$ in diameter and $100{\sim}190\;{\mu}m$ in height. The holes were prepared by DRIE method. Ta was sputtered for copper diffusion barrier followed by copper seed layer IMP sputtering. Via specimen were filled by DC, pulse and pulse-reverse current electroplating methods. The effects of additives and current types on copper deposits were investigated. Vertical and horizontal cross section of via were observed by SEM to find the defects in via. When pulse-reverse electroplating method was used, defect free via were successfully obtained.

• Journal of the Korean Chemical Society
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• v.37 no.8
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• pp.702-710
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• 1993

Electrochemical reduction of thionyl chloride has been carried out at glassy carbon and molybdenum electrodes, the surface of which is modified by binuclear tetradentate schiff base Co(II), Ni(II),Cu(II) and Fe(II) complexes. The catalyst molecules of transition metal(II) complexes were adsorbed on the electrode surface and reduced thionyl chloride resulting in a generation of oxidized catalyst molecules. There was an optimum concentration for each catalyst compound. The catalytic effects of SOCl$_2$ reduction were larger on glassy carbon electrodes compared to molybdenum electrodes and enhancements in reduction current of up to 120${\%}$ at the glassy carbon electrodes. The reduction currents of thionyl chloride were increased and the reduction potentials were shifted to the negative potential when scan rates became faster. The reduction of thionyl chloride was proceed to diffusion controlled reaction.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.2 s.35
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• pp.129-134
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• 2005

Electroplating copper is the important role in formation of 3D stacking interconnection in SiP (System in Package). The I-V characteristics curves are investigated at different electrolyte conditions. Inhibitor and accelerator are used simultaneously to investigate the effects of additives. Three different sizes of via are tested. All via were prepared with RIE (reactive ion etching) method. Via's diameter are 50, 75, $100{\mu}m$ and the height is $100{\mu}m$. Inside via, Ta was deposited for diffusion barrier and Cu was deposited fer seed layer using magnetron sputtering method. DC, pulse and pulse revere current are used in this study. With DC, via cannot be filled without defects. Pulse plating can improve the filling patterns however it cannot completely filled copper without defects. Via was filled completely without defects using pulse-reverse electroplating method.

• Analytical Science and Technology
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• v.7 no.4
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• pp.483-492
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• 1994

Direct solid analysis of various kinds of metal samples has been conducted by glow discharge. In this laboratory, the gas-jet assisted glow discharge(GJGD) device has been developed and characterized. The effect of changes in applied current, cell pressure and flow rate on atomic emission signals obtained from a jet-assisted cathodic sputtering was investigate. The emission intensities of Cu, Zn, and Ar were measured. They were increased with the current. But the intensities were decreased by increasing the flow rate of argon due to the diffusion and transportation of particles into plasma. By increasing the pressure of the cell, the intensities were greatly decreased because of enhancement of redeposition onto the surface of the sample.

• Journal of the Mineralogical Society of Korea
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• v.25 no.2
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• pp.85-94
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• 2012

The $AsO_4$ ion in acid mine drainage has been known to substitute for $SO_4$ in schwertmannite and prevent schwertmannite from being converted to goethite. There have been studies on the heavy metal sorption on schwertmannite, but no experimental results have been reported on the characteristics of heavy metal sorption on $AsO_4$-substituted schwertmannite. In this study, we conducted sorption experiments of Cu, Pb, and Zn on the $AsO_4$-substituted schwertmannite at pH 4 and 6 in the solution of 3, 10, 30, and 100 mg/L concentrations. For all heavy metals, the sorbed heavy metals significantly increase at pH 6 compared with at pH 4. At both pH 4 and 6, Pb shows the highest sorption capacity and those of Cu and Zn are similar. With increasing time, the sorbed heavy meal contents increase too. However, in the case of Zn, the most sorptions occur at the initial stage and no significant increase is observed with time. Among the concentration ranges in which we conducted the experiment, the increasing trend is clear in high concentrated solutions such as 100 mg/L. We applied several sorption kinetic model and it shows that the diffusion process may be the most important factor controlling the sorption kinetics of Cu, Pb, and Zn on $AsO_4$-substituted schwertmannite. Considering the previous results that pure schwertmannite has similar sorption capacity for all three heavy metals at pH 6 and has higher sorption capacity for Cu and Pb than Zn at pH 4, our experiments indicates that substitution of $AsO_4$ for $SO_4$ on schwertmannite changes surface and sorption characteristics of schwertmannite. It also shows that $AsO_4$ contributes not only to the stability of schwertmannite, but also to the mobility of heavy metals in acid mine drainage.