• Journal of the Microelectronics and Packaging Society
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• v.12 no.2 s.35
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• pp.111-119
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• 2005

Stack specimen with three dimensional interconnection structure through Cu via of $75{\mu}m$ diameter, $90{\mu}m$ height and $150{\mu}m$ pitch was successfully fabricated using subsequent processes of via hole formation with Deep RIE (reactive ion etching), Cu via filling with pulse-reverse electroplating, Si thinning with CMP, photolithography, metal film sputtering, Cu/Sn bump formation, and flip chip bonding. Contact resistance of Cu/Sn bump and Cu via resistance could be determined ken the slope of the daisy chain resistance vs the number of bump joints of the flip chip specimen containing Cu via. When flip- chip bonded at $270^{\circ}C$ for 2 minutes, the contact resistance of the Cu/Sn bump joints of $100{\times}100{\mu}m$ size was 6.7m$\Omega$ and the Cu via resistance of $75{\mu}m$ diameter, $90{\mu}m$ height was 2.3m$\Omega$.

• Journal of Adhesion and Interface
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• v.4 no.3
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• pp.33-40
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• 2003

In this work, diglycidyl ether of bisphenol A (DGEBA)/polyetherimide (PEI) blends were cured using 4,4-diaminodiphenyl methane (DDM). And the effects of addition of different PEI contents to neat DGEBA were investigated in the thermal properties and fracture toughness of the blends. The contents of contents of containing PEI were varied in 0, 2.5, 5, 7.5, and 10 phr. The cure activation energies ($E_a$) of the cured specimens were determined by Kissinger equation and the mechanical interfacial properties of the specimens were performed by critical stress intensity factor ($K_{IC}$). Also their surfaces were examined by using a scanning electron microscope (SEM) and the surface energetics of blends was determined by contact angles. As a result, $E_a$ and $K_{IC}$ showed maximum values in the 7.5 phr PEI. This result was interpreted in the increment of the network structure of DGEBA/PEI blends. Also, the surface energetics of the DGEBA/PEI blends showed a similar behavior with the results of $K_{IC}$. This was probably due to the improving of specific or polor component of the surface free energy of DGEBA/PEI blends, resulting in increasing the hydrogen bonding of the hydroxyl and imide groups of the blends.

• Journal of the Korean Chemical Society
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• v.37 no.3
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• pp.302-308
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• 1993

Monolayers of calcium palmitate were deposited on a piezoelectric quartz crystal plate by the Langmuir-Blodgett(LB) technique, and it was found from frequency changes of the quartz crystal deposited LB films. The usual carbonyl absorbance at 1704 cm$^{-1}C$ was replaced by the split band in the 1540~1590 cm$^{-1}C$. The two absorptions at 1580 cm$^{-1}C$ and 1540 cm$^{-1}C$ were assigned to the antisymmetric stretching vibration of the calcium carboxylate group and the hydrated species due to the lowering carbonyl stretching frequency by hydrogen bonding$^1$ respectively. Besides, it was demonstrated by X-ray diffraction analysis. The swelling behaviour of LB films in water phase at 23$^{\circ}C$ was observed from the frequency change of the LB films deposited quartz crystal with time. Calcium palmitate LB films has been found to swell substantially in water without flaking, whereas hexadecanol LB films hardly swelled in water. Amount of swelling of calcium palmitate LB films was equivalent to 47 wt.${\%}$ of the dry LB films, which means that ca. 7 water molecules were incorporated per calcium palmitate amphiphile. Chemical structure of calcium palmitate LB film was estimated as [CH$_3$(CH$_2$)$_{14}$COO]$_2$Ca${\cdot}$XH$_2$O, and the hydration number was 1.

• Membrane Journal
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• v.15 no.3
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• pp.247-254
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• 2005

Chitosan film has potential applications in agriculture, food, and pharmacy. However, films made only from chitosan lack gas barrier and have poor mechanical properties. For enhanced gas barrier and mechanical properties, chitosan/clay nanocomposites have been prepared with montmorillonite (MMT) which is a layered structure of clays and chitosan. The cationic biopolymer, chitosan is intercalated into $Na^+-montmorillonite$ through cationic exchange and hydrogen bonding process. Diluted acetic acid is used as solvent f3r dissolving and dispersing chitosan. Chitosan was intercalated or exfoliated in MMT and it was confirmed by X-ray diffraction method. D-spacing of the characteristic peak from MMT plate in chitosan/clay nanocomposites was moved and diminished. The thermal stability and the mechanical properties of the nanocomposites are measured by TGA and Universal Testing Machine. Gas permeability through the chitosan/clay nanocomposites films decreased due to increased tortuosity made by intercalation of clay in chitosan.

• The KIPS Transactions:PartA
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• v.16A no.2
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• pp.113-124
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• 2009

With increasing multicore system, much effort has been put on the performance improvement of its application. Because multicore system has multiple processing devices in one system, its processing power increases compared to the single core system. However in many cases the advantages of multicore can not be exploited fully because the existing software and hardware were designed to be suitable for single core. When the existing software runs on multicore, its performance improvement is limited by the bottleneck of sharing resources and the inefficient use of cache memory on multicore. Therefore, according as the number of core increases, it doesn't show performance improvement and shows performance drop in the worst case. In this paper we propose a method of performance improvement of multicore system by applying Flow-Level Parallelism to the existing TCP/IP network application and operating system. The proposed method sets up the execution environment so that each core unit operates independently as much as possible in network application, TCP/IP stack on operating system, device driver, and network interface. Moreover it distributes network traffics to each core unit through L2 switch. The proposed method allows to minimize the sharing of application data, data structure, socket, device driver, and network interface between each core. Also it allows to minimize the competition among cores to take resources and increase the hit ratio of cache. We implemented the proposed methods with 8 core system and performed experiment. Experimental results show that network access speed and bandwidth increase linearly according to the number of core.

• Korean Journal of Materials Research
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• v.9 no.12
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• pp.1211-1215
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• 1999

Fluorinated amorphous carbon (a-C:F) films were prepared by an electron cyclotron resonance chemical vapor deposition (ECRCVD) system using a gas mixture of $C_2F_6$ and $CH_4$ over a range of deposition temperature (room temperature ~ 300$^{\circ}C$). 500$^{\AA}C$ thick DLC films were pre-deposited on Si substrate to improve the strength between substrate and a-C:F film. The chemical bonding structure, chemical composition, surface roughness and dielectric constant of a-C:F films deposited by varying the deposition temperature were studied with a variety of techniques, such as Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS), atomic force microscopy (AFM) and capacitance-voltage(C-V) measurement. Both deposition rate and fluorine content decreased linearly with increasing deposition temperature. As the deposition temperature increased from room temperature to 300$^{\circ}C$, the fluorine concentration decreased from 53.9at.% down to 41.0at.%. The dielectric constant increased from 2.45 to 2.71 with increasing the deposition temperature from room temperature to 300$^{\circ}C$. The film shrinkage was reduced with increasing deposition temperature. This results ascribed by the increased crosslinking in the films at the higher deposition temperature.

• Korean Journal of Materials Research
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• v.3 no.3
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• pp.282-291
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• 1993

Joining ${Al}_{2}{O}_{3}$ and STS 304 stainless steel by active metal brazing method with using CuI Owt % Ti and Cu -7 .5wt % Zr insert metal, their interfaces were analyzed and strength of the joint brazed with Cu-7.5wt % Zr insert metal also investigated with shear strength testing method. In brazing with Cu-lOwt% Ti insert metal, the single reaction layer was formed by the reaction with Ti and ${Al}_{2}{O}_{3}$ at the interface between ${Al}_{2}{O}_{3}$ and insert metal, but the double reaction layer was found in brazing with Cu-7.5wt % Zr insert metal because of the difference of their wettability on the surface of ${Al}_{2}{O}_{3}$. Fracture shear strength about 86MPa was obtained from ${Al}_{2}{O}_{3}$/Cu-7.5wt% Zr/STS 304 stainless steel joint and reasonable strength of the joints is attributed to the formation of double reaction layer at the interface.

• Applied Chemistry for Engineering
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• v.16 no.2
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• pp.250-256
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• 2005

Coating appearance is the most important problem in automotive industry. To increase the coating appearance quality, the corrosion resistance and the coating adhesion on metal substrates must be basically solved. The phosphating film made by the pretreatment of metal substrate is important factor to increase the coating adhesion. During the cathodic electrodeposition, the pH at the cathode surface increases up to about 12. In such a highly alkaline condition, the dissolution of metal substrate and phosphate film occurs. These phenomena result in the decrease of the bonding strength between the phosphating film and the substrate. Generally, the structure of zinc phosphating film is hopeite or phosphophyllite. It has been known that the phosphophyllite film contains better corrosion resistance and paint adhesion for hot water immersion test because of the decrease of dissolving amount of both metal substrate and phosphating film during the cathodic electrodeposition. It is found that the addition of Ni and Mn composition increase P-ratio and then can improve the paint adhesion on metal surface and the corrosion resistance.

• Journal of the Korean Institute of Gas
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• v.2 no.4
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• pp.18-24
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• 1998

Polyurethane (PU) synthesized from 4,4'-diphenylmethane diisocyanate having high functionality (f=2.9) and polyester polyol have been investigated by differential scanning calorimeter (DSC), dynamic mechanical thermal analyzer (DMTA), and Fourier transform infrared spectroscope (FT-IR). From the DSC measurement of polyurethane, a single transition temperature ($T_g$) was observed. This result indicates that polyurethanes synthesized in this work have homogeneous network structure due to high functionality of diisocyanate. It was also found that the $T_g$ of polyurethane was increased as hard segment content was increased. The results from DMTA measurement are consistent with DSC results. In order to investigate the effect of thermal annealing on the $T_g$ of polyurethane, the samples were annealed at various annealing conditions. $T_gs$ of polyurethanes were found to increased with annealing temperature. From swelling experiment and FT-IR studies, it was found that the $T_g$ was increased as crosslinking density of polyurethane was increased.

• Journal of Radiation Industry
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• v.9 no.4
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• pp.217-221
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• 2015

When reactor coolant leaks occur due to cracks of a steam generator's tube, radioactive materials contained in the primary cooling water in nuclear power plant are forced out toward the secondary systems. At this time the secondary water purification resin in the ion exchange resin tower of the steam generator blowdown system is contaminated by the radioactivity of the leaked radioactive materials, so we pack this in special containers and store temporarily because we could not dispose it by ourselves. If steam generator tube leakage occurs, it produces contaminated spent resins annually about 5,000~7,000 liters. This may increase the amount of nuclear waste productions, a disposal working cost and a unit price of generating electricity in the plant. For this reasons, it is required to develop a decontamination process technique for reducing the radioactive level of these resins enough to handle by the self-disposal method. In this research, First, Investigated the structure and properties of the ion exchange resin used in a steam generator blowdown system. Second, Checked for a occurrence status of contaminated spent resin and a disposal technology. Third, identified the chemical characteristics of the waste radionuclides of the spent resin, and examined ionic bonding and separation mechanism of radioactive nuclear species and a spent resin. Finally, we carried out the decontamination experiment using chemicals, ultrasound, microbubbles, supercritical carbon dioxide to process these spent resin. In the case of the spent resin decontamination method using chemicals, the higher the concentration of the drug decontamination efficiency was higher. In the ultrasound method, foreign matter of the spent resin was removed and was found that the level of radioactivity is below of the MDA. In the microbubbles method, we found that the concentration of the radioactivity decreased after the experiment, so it can be used to the decontamination process of the spent resin. In supercritical carbon dioxide method, we found that it also had a high decontamination efficiency. According to the results of these experiments, almost all decontamination method had a high efficiency, but considering the amounts of the secondary waste productions and work environment of the nuclear power plant, we judged the ultrasound and supercritical carbon dioxide method are suitable for application to the plant and we established the plant applicable decontamination process system on the basis of these two methods.