• Journal of Surface Science and Engineering
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• v.54 no.5
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• pp.207-212
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• 2021

The mechanical and electrical characteristics can be improved in 3D stacked IC technology which can accomplish the ultra-high integration by stacking more semiconductor chips within the limited package area through the Cu direct bonding method minimizing the performance degradation to the bonding surface to the inorganic compound or the oxide film etc. The surface was treated in a ultrasonic washer using a diamond abrasive to remove other component substances from the prepared cast plate substrate surface. FE-SEM was used to analyze the bonding characteristics of the bonded copper substrates, and the cross section of the bonded Cu conjugates at the sintering junction temperature of 100 ℃, 150 ℃, 200 ℃, 350 ℃ and the pressure of 2303 N/cm² and 3087 N/cm². At 2303 N/cm², the good bonding of copper substrate was confirmed at 350 ℃, and at the increased pressure of 3087 N/cm², the bonding condition of Cu was confirmed at low temperature junction temperature of 200 ℃. However, the recrystallization of Cu particles was observed due to increased pressure of 3087 N/cm² and diffusion of Cu atoms at high temperature of 350 ℃, which can lead to degradation in semiconductor manufacturing.

• Cross-Cultural Studies
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• v.44
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• pp.29-58
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• 2016

'Post-memory' is the act of remembering traumatic events in history by subsequent generations who have not had direct experiences or relations with them. For this reason, the narratives of 'post-memory' are considered as re-interpretations of the past deeply influenced by current perspectives and concerns. The Chilean film NO goes back to the Referendum of 1988 in order to examine the "NO campaign" which was opposed to another eight years of continuation of the Pinochet regime. Although this campaign contributed significantly to the Chilean democratization, the filmmaker does not just celebrate it: rather he attempts to cast a critical reflection on its strategies that eventually turned democracy into a "commodity" by deploying commercial language and marketing tools for characterizing and describing it. On the other hand, the Korean movie The Attorney sheds light on the story of an attorney who, during the military regime in the 1980's, became a human rights lawyer when he tried to advocate for university students accused of violating national security law. This film reconstitutes the meaning of democracy built upon the logic of "common-sense" that privileges freedom and fundamental human rights over Statism. Despite the different historical contexts between Chile and South Korea, these two movies retell the history of a dictatorship that ended a couple of decades ago. In doing so, they raise questions about history, memory and democracy in order to deepen the understanding of current social and political circumstances while placing an emphasis on the roles and responsibilities of intellectuals during the transition to democracy and democratic consolidation.

• Applied Chemistry for Engineering
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• v.18 no.3
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• pp.234-238
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• 2007

Highly conducting Polypyrroles soluble in organic solvents were synthesized using functional doping agents, such as mixed dopants [sodium di(2-ethylhexyl)sulfosuccinate (DEHSNa) Naphthalenesulfonic acid (NSA), DEHSNa Toluenesulfonic acid (TSA), DEHSNa Dodecylbenzensulfonic acid (DBSA)] and mixed oxidants [$(NH_4)_2S_2O_8{\cdot}FeCl_3$, $(NH_4)_2S_2O_8{\cdot}Fe_2(SO_4)_3$]. Ppy-DEHS powder using an oxidant, such as $(NH_4)_2S_2O_8$ (10 wt%/vol.) showed higher solubility than the mixed dopant (DEHSNa NSA, 3 wt%/vol.) and mixed oxidant [$(NH_4)_2S_2O_8{\cdot}Fe_2(SO_4)_3$, 4 wt%/vol.] in DMF solvent. But Ppy-DEHS free standing film using a mixed dopant, such as DEHSNa NSA (16 S/cm) and a mixed oxidant, such as $(NH_4)_2S_2O_8{\cdot}Fe_2(SO_4)_3$ (13 S/cm) cast from DMF solvent showed higher electrical conductivity than $(NH_4)_2S_2O_8$ (2 S/cm). For the Ppy-DEHS films using various condition cast from DMF solvent, three dimensional various range hopping model (3D VRH ; $\{{\sigma}_{dc}(T)={\sigma}_oexp[-(T_o/T)^{1/4}]\}$) provided fit to the results of temperature dependence of electrical conductivity measurement.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.4
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• pp.409-414
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• 2008

Porous carbon electrode for electrosorption was prepared by a wet phase inversion method. Carbon slurry that was a mixture of activated carbon powder(ACP) and PVdF solution was cast directly upon a graphite sheet by means of a casting knife. Porous carbon electrodes were fabricated by immersing the cast film in pure water as a non solvent. Physical and electrochemical properties of carbon electrodes prepared with various ACP contents(50.0, 75.0, 83.3, 87.5, 90.0 wt %). From the SEM images we can verify that the electrode was porous. The average pore sizes determined for the electrodes fabricated with various ACP contents ranged from 72.7 to 86.4 nm and the size decreased as the ACP content increased. The electrochemical properties were characterized by cyclic voltammetry(CV) method. All of the voltammograms showed typical behavior of an electric double layer charging/discharging on the carbon surface. The capacitance increased with the ACP content and the values ranged from 2.18 F/cm$^2$ for 50 wt% ACP to 4.77 F/cm$^2$ for 90 wt% ACP.

• Applied Chemistry for Engineering
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• v.19 no.2
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• pp.185-190
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• 2008

In order to increase the surface area of electrodes for electrosorption, porous carbon electrodes were fabricated by a wet phase inversion method. A carbon slurry consisting of a mixture of activated carbon powder (ACP), polyvinylidene fluoride (PVdF), and N-methyl-2-pyrrolidone (NMP) as a solvent was cast directly on a graphite sheet. The cast film was then immersed in pure water for phase inversion. The physical and electrochemical properties of the electrodes were investigated using scanning electron microscopy (SEM), porosimetry, and cyclic voltammetry. The SEM images verified that the pores of various sizes were formed uniformly on the electrode surface. The average pore sizes determined for the electrodes fabricated with various NMP contents ranged from 64.2 to 82.4 nm and the size increased as the NMP content increased. All of the voltammograms showed a typical behavior of charging and discharging characteristic at the electric double layer. The electrical capacitance ranged from 3.88 to $5.87F/cm^2$ depending on the NMP contents, and the electrical capacitance increased as the solvent content decreased. The experimental results showed that the solvent content is an important variable controlling pore size and ultimately the capacitance of the electrode.

• Journal of the East Asian Society of Dietary Life
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• v.23 no.4
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• pp.461-469
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• 2013

This research is performed to investigate the changes in the physicochemical properties and microbial growths of seasoned anchovies with various packaging materials (PET/CPP : polyethylene terephthalate/cast polypropylene, PET/EVOH : polyethylene terephthalate/ethylene-vinyl alcohol, PET/AL/LDPE: polyethylene terephthalate/aluminum/low density polyethylene), which are stored at various temperatures (25, 35, $45^{\circ}C$) for 60 days. Generally, it is being observed that changes in physicochemical properties (i.e., moisture content, color, brown intensity, TBA value, TMA, VBN etc) of seasoned anchovies are significant when stored at higher temperatures. Particularly, the packaging materials are found to influence substantially on the physicochemical properties of seasoned anchovies. With packaging materials of high oxygen transmission rates and moisture vapor transmission rates (i.e., PET/CPP), the changes in physicochemical properties of seasoned anchovies are significant, while being low with low oxygen transmission rates and low moisture vapor transmission rates (i.e., PET/EVOH). In addition, results of microbial growths in seasoned anchovies show that significant increases in total aerobic bacteria counts (about 100-fold after 60 day of storage) are observed in samples with packaging materials of high oxygen transmission rates and moisture vapor transmission rates (i.e, PET/CPP), while with only small increases for samples of low oxygen transmission rates and low moisture vapor transmission rates (i.e., PET/EVOH). Based on the changes in the physicochemical properties and results of microbial growths, it is being concluded that PET/EVOH film is suitable for the packaging of seasoned anchovies.

• Journal of Pharmaceutical Investigation
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• v.38 no.3
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• pp.163-169
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• 2008

Liposomes are spherical vesicles composed of lipid bilayer membranes. However, the conventional liposomes have been found to be plagued by rapid opsonization and taken up by the reticuloendothelial system (RES), resulting in shortened circulation time and limited intracellular uptake to target cell. In this study, polyethyleneglycol-cationic liposomes (PCL) containing cationic lipid and DSPE-mPEG were prepared by thin film cast-hydration method. The PEG liposomes had approximately $97.0{\pm}1.3\;nm$ of mean particle diameter and $-21.7{\pm}1.2\;mV$ of zeta potential value. PCL had $96.4{\pm}1.8\;nm$ of mean particle diameter and $-8.7{\pm}1.1\;mV$ of zeta potential value with a decrease of about 10 mV compared to the PEG liposomes. Loading of model drug, doxorubicin (DOX), in liposomes were carried out by using remote loading method and the loading efficiency of DOX in liposomes was about $95.0{\pm}1.9%$. Intracellular uptake and cytotoxicity of PCL were higher than that of PEG liposomes to murine B16F10 melanoma cells. In addition, anti-tumor activity of PCL was similar to that of PEG liposomes on growth of A549 human lung carcinoma in BALB/c mice. Consequently, PCL modified with cationic lipid may be applicable as anticancer drug carriers that can increase intracellular uptake and therapeutic efficacy.

• Polymer(Korea)
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• v.25 no.3
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• pp.421-426
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• 2001

11-Aminododecanoic acid, to insert the functional group of -COOH reacted with the end group of poly($\varepsilon$-caprolactone) diol, and cetyltrimethylammonium bromide (CTMA), to increase the d-spacing of Montmorillonite (MMT), were intercalated into $Na^+;_-$MMT. The modified MMT was reacted with poly(${varepsilon}-caprolactone$) diol ($M_n{=2000$) in THF solution at $80^{\circ}C$ for 4 hrs. After reaction, poly(${varepsilon}-caprolactone$) ($M_n{=80000$) was mixed into the solution for 12 hrs. To prepare the PCL/clay nanocomposite film this solution was cast into the silicon mold at $60^{\circ}C$ in vacuum oven for 6 hrs. From the results of XRD and TEM, it was found that the exfoliated PCL/clay nanocomposite were prepared. The effects of the amount of MMT on the mechanical properties and thermal properties of PCL/clay nanocomposites have been investigated by tensile tester and DSC. Because the MMT was dispersed homogeneously in PCL matrix, the Young's modulus of the nanocomposite were found to be excellent. However, MMT dispersed in PCL matrix had almost no effect on the tensile strength of the composites. The crystallization temperature of PCL increased in proportion to 3 wt% MMT in the PCL matrix.

• Polymer(Korea)
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• v.34 no.5
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• pp.391-397
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• 2010

Poly(amic acid)(PAA) was prepared by reaction of bicyclo(2,2,2)oct-7-ene-2,3,5,6-tetracarboxylicdianhydride(BTDA) containing double bond for crosslinking and bis[4-(3-aminophenoxy) phenyl] sulfone(BAPS) in N,N-dimethylacetamide(DMAc). The cast film of PAA was heat-treated at different temperatures to create polyimide(PI) films. With increasing thermal crosslinking temperatures from 250 to $350^{\circ}C$, the thermo-mechanical properties, degree of crosslinking, and optical transparency of the cross-linked PI were investigated. The maximum enhancement in the thermo-mechanical properties was observed at a heat treatment condition of $350^{\circ}C$. However, the optical transparency was found to be optimal for $250^{\circ}C$ heat treatment. The degree of crosslinking in NMR was determined to be 85% to 93% with increasing annealing temperature conditions from 250 to $350^{\circ}C$.

• Composites Research
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• v.28 no.5
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• pp.270-276
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• 2015

Polyvinylidene fluoride (PVDF)-based nanocomposites are fabricated by incorporation of boron nitride (BN) nanosheets with anisotropic orientation for a potential high thermal conducting ferroelectric materials. The PVDF is dissolved in dimethylformamide (DMF) and homogeneously mixed with exfoliated BN nanosheets, which is then cast into a polyimide film under application of high magnetic fields (0.45~10 T), where the direction of the filler alignment was controlled. The BN nanosheets are exfoliated by a mixed way of solvothermal method and ultrasonication prior to incorporation into the PVDF-based polymer suspension. X-ray diffraction, scanning electron microscope and thermal diffusivity are measured for the characterization of the polymer nanocomposites. Analysis shows that BN nanosheets are exfoliated into the fewer layers, whose basal planes are oriented either perpendicular or parallel to the composite surfaces without necessitating the surface modification induced by high magnetic fields. Moreover, the nanocomposites show a dramatic thermal diffusivity enhancement of 1056% by BN nanosheets with perpendicular orientation in comparison with the pristine PVDF at 10 vol % of BN, which relies on the degree of filler orientation. The mechanism for the magnetic field-induced orientation of BN and enhancement of thermal property of PVDF-based composites by the BN assembly are elucidated.