• Korean Journal of Materials Research
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• v.8 no.5
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• pp.444-449
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• 1998

There are various shielding materials that have been considered; the use of a metallic plate or the layering of a conductive material on a plastic surface and the insertion of filler in plastics. All of these methods have shown their merits and weakness. Therefore, many studies have concentrated on developing materials that effectively cut down EMI without increase in weights of housing materials. In these respects, this study has focused on investigations of the shielding effect of materials that have electroless nickel plating on the lamella structured micro particles surface with low specific gravity. When a film of electroless nickel were plated on a micro particle surfaces and then mixed with paint, the electromagnetic shielding effects were measured as 63dB. Although these effects were less than that 90dB of the copper plate, trials in a series of 6 times increased the shielding effect by IOdB and is applicable to wide range of EMI shielding.

• Korean Journal of Materials Research
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• v.19 no.7
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• pp.349-355
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• 2009

Metal thin film patterns on a LTCC substrate, which was connected through inner via and metal paste for electrical signals, were formed by a screen printing process that used electric paste, such as silver and copper, in a conventional method. This method brought about many problems, such as non uniform thickness in printing, large line spaces, and non-clearance. As a result of these problems, it was very difficult to perform fine and high resolution for high frequency signals. In this study, the electric signal patterns were formed with the sputtered metal thin films (Ti, Cu) on an LTCC substrate that was coated with protective oxide layers, such as $TiO_2$ and $SiO_2$. These electric signal patterns' morphology, surface bonding strength, and effect on electro plating were also investigated. After putting a sold ball on the sputtered metal thin films, their adhesion strength on the LTCC substrate was also evaluated. The protective oxide layers were found to play important roles in creating a strong design for electric components and integrating circuit modules in high frequency ranges.

• Korean Journal of Metals and Materials
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• v.49 no.5
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• pp.388-394
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• 2011

High speed copper filling into TSV (through-silicon-via) for three dimensional stacking of Si chips was investigated. For this study, a tapered via was prepared on a Si wafer by the DRIE (deep reactive ion etching) process. The via had a diameter of 37${\mu}m$ at the via opening, and 32${\mu}m$ at the via bottom, respectively and a depth of 70${\mu}m$. $SiO_2$, Ti, and Au layers were coated as functional layers on the via wall. In order to increase the filling ratio of Cu into the via, a PPR (periodic pulse reverse) wave current was applied to the Si chip during electroplating, and a PR (pulse reverse) wave current was applied for comparison. After Cu filling, the cross sections of the vias was observed by FE-SEM (field emission scanning electron microscopy). The experimental results show that the tapered via was filled to 100% at -5.85 mA/$cm^2$ for 60 min of plating by PPR wave current. The filling ratio into the tapered via by the PPR current was 2.5 times higher than that of a straight via by PR current. The tapered via by the PPR electroplating process was confirmed to be effective to fill the TSV in a short time.

• Membrane Journal
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• v.28 no.4
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• pp.252-259
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• 2018

An acidic, real metal-plating wastewater was treated by a fluidized bed membrane reactor introduced with granular activated carbon (GAC) as fluidized media. With GAC fluidization, there was no increase in suction pressure with time at each flux set-point applied. At neutral solution pH, much less fouling rate was observed than acidic pH under GAC fluidization. Higher solution pH resulted in the increase in particle size in metal-finishing wastewater, thus producing a less dense cake structure on membrane. More than 95% of chemical oxygen demand was observed from the fluidized bed membrane reactor under GAC fluidization. Total suspended solid concentration in membrane permeate was near zero. At the raw wastewater pH, no removal of copper and chromium by the fluidized bed membrane reactor was observed. As the pH was increased to 7.0, removal efficiency of copper and chromium was increased considerably to 99 and 94%, respectively. Regardless of solution pH tested, more than 95% of cyanide was removed possibly due to the strong adsorption of organic-cyanide complex on GAC in fluidized bed membrane reactor.

• Applied Chemistry for Engineering
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• v.23 no.3
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• pp.313-319
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• 2012

In this work, the electroplating of copper was introduced on PAN-based carbon fibers for the enhancement of mechanical interfacial strength of carbon fibers-reinforced composites. The surface properties of carbon fibers were determined by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and contact angle measurements. Its mechanical interfacial properties of the composites were studied by interlaminar shear strength (ILSS) and critical stress intensity factor ($K_{IC}$). From the results, it was found that the mechanical interfacial properties of Cu-plated carbon fibers-reinforced composites (Cu-CFRPs) enhanced with increasing the Cu plating time, Cu content and COOH group up to Cu-CFRP-30. However, the mechanical interfacial properties of the Cu-CFRPs decreased dramatically in the excessively Cu-plated CFRPs sample. In conclusion, the presence of Cu particles on carbon fiber surfaces can be a key factor to determine the mechanical interfacial properties of the Cu-CFRPs, but the excessive Cu content can lead the failure due to the interfacial separation between fibers and matrices in this system.

• The korean journal of orthodontics
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• v.35 no.2 s.109
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• pp.127-136
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• 2005

The purpose of this study was to examine the cytotoxicity of orthodontic wire which had an increased diameter through electroplating, and to evaluate its possible clinical applications, First. nickel plating was carried out on the commercially available stainless steel wire using an electroplating technique For the comparison of the electroplated wire with ready made stainless steel wire and titanium or copper. each wire was incubated for 72 hours in a medium. The release of the metal ion was measured using ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrophotometer). Balb/c 3T3 mouse fibroblast was put on a microplate and placed in an incubated medium of 75%, 50%, and 20% dilation. An MTT analysis was used to compare with the medium only. The change in absorbency value of each wire group and the difference of absorbency value according to the change of dilution was measured The results of ICP-AES analysis showed that great amount nickel iou was isolated from electroplated orthodontic wires and great amount copper ion was isolated from copper. The results of the MTT analysis showed that there was no difference in the absorbency value of titanium at any dilution. However, the electroplated wires (p<0.001) the stainless steel wires (p<0.05) and the copper (P<0.001) were statistically significantly lower than those of medium only at all dilutions. Assessment as per ISO 10993, part 5, showed that electroplated wire was alloted to 'moderate cytotoxic' the titanium and stainless steel wire were 'non-cytotoxic' The results of this study indicate that the electroplated orthodontic wires need additional efforts to decrease cytotoxicity for their clinical applications.

• Journal of the Korean Electrochemical Society
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• v.4 no.4
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• pp.160-165
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• 2001

The eletrochemical charateristics of mercapto compound additives on the copper electroplating for semi conductor metalization were investigated. Mercapto compounds including sulfur atom is known that they activate deposition rate in eletroplating. Four different types of mercapto compounds were chosen with different concentration and both the characteristics of plating and throwing power were investigated by electrochemical experiments such as Hull cell test, Haring-Blum cell, cathodic polarization, EQCM(Electrochemical Quartz Crystal Microbalance). 3-Mercapto-1-propanesulfonic acid among 4 different mercapto compounds was regarded as the most proper activator with the results of the mass change of Cu metal deposited on eletrode by cathodic polarization and EQCM. The overpotential was more shifted to 100 mV in the concentration of 20 ppm than the solution with only $Cl^-$ in cathodic scan.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.7
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• pp.701-708
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• 2011

Natural convection heat transfers on inclined flat plates were measured for Grashof numbers of $8.06{\times}10^7$ and $3.45{\times}10^9$ by using a copper sulfate electroplating system. The inclinations of the plates were varied from upward-facing horizontal to downward-facing horizontal. Test results for the downward-facing plate agree well with the existing theory that the Nusselt number can be calculated by replacing gravitational acceleration, g with g $cos{\theta}$ in the heat transfer correlation for the vertical plate. The natural convection flows for the upward-facing plate follow two distinct flow regimes: boundary layer regime and flow separation regime. The copper plating pattern for the upward-facing plates clearly reveals the flow separation points.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.421-421
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• 2008

Generally, the polymer thick-film resistors for embedded organic or hybrid substrate are patterned by screen printing so that the accuracy of resistor pattern is not good and the tolerance of resistance is too high(${\pm}$20~30%). To reform these demerits, a method using Fodel$^{(R)}$ technology, which is the patterning method using a photosensitive resin to be developable by aqueous alkali-solution as a base polymer for thick-film pastes, was recently incorporated for the patterning of thermosetting thick-film resistor paste. Alkali-solution developable photosensitive resin system has a merit that the precise patterns can be obtained by UV exposure and aqueous development, so the essential point is to get the composition similar to PSR(photo solder resist) used for PCB process. In present research, we made the photopatternable resistor pastes using 8 kinds of epoxy acrylates and a conductive carbonblack (CDX-7055 Ultra), evaluated their developing performance, and then measured the resistance after final curing. To become developable by alkali-solution, epoxy acrylate oligomers with carboxyl group were prepared. Test coupons were fabricated by patterning copper foil on FR-4 CCL board, plating Ni/Au on the patterned copper electrode, applying the resistor paste on the board, exposing the applied paste to UV through Cr mask with resistor patterns, developing the exposed paste with aqueous alkali-solution (1wt% $Na_2CO_3$), drying the patterned paste at $80^{\circ}C$ oven, and then curing it at $200^{\circ}C$ during 1 hour. As a result, some test compositions couldn't be developed according to the kind of oligomer and, in the developed compositions, the measured resistance showed different results depending on the paste compositions though they had the same amount of carbonblack.

• Conservation Science in Museum
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• v.16
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• pp.14-31
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• 2015

Sword with round pommel discovered in tomb No.39 in the Jisandong tumuli group (M310) is a large sword with a looped pommel enclosing a sculpted dragon head. The sword was produced using different techniques; gold decoration, plating, openwork carving and hammering by using gold and silver. This sword treated conservation work because it has deformation and damages of handle decoration, missing part of sword, and corrosion. Conservation treatment was that foreign material and corroded metal were removed from the surface, and performed to stabilize and reinforce the weakened metal. During the conservation treatment, the object was examined to understand its materials and production method. The result of research, the dragon head inside the looped, amalgam-plated pommel has surface gold decorations. The pommel has a thin gold plate placed over a bottom plate made of copper, which was hammered to create an embossed design. The silver plate-covered hilt, cylindrical in shape, has an openwork lattice design. The steel blade is single-edged. Finally, the locket of the sheath has an embossed design also created through hammering on a thin gold plate placed over the copper bottom plate.