• Journal of computational fluids engineering
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• v.18 no.3
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• pp.20-25
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• 2013

In various manufacturing industries, an in-mold decoration (IMD) process for plastic objects is widely utilized because a film forming and an injection molding processes run simultaneously. In the present study, the deformation of polymer film and filling of resin in the IMD process were numerically investigated to evaluate the quality of the plastic object formed by the IMD process, which consists of thermoforming and injection molding processes. To obtain the initial shape of the polymer film during the injection molding process, the deformation of the polymer film in the thermoforming process was pre-formed using the vacuum conditions to attach the film to a cavity. Since the properties and deformation of polymer film are greatly affected by the behavior of polymer resin being injected into a mold cavity, numerical simulations for the injection molding and film forming were performed with one-way coupling method. The results showed that the injected resin could lead to the tearing of the polymer film in local regions near the corners. In order to verify the proposed numerical methodology, the numerical results of the deformation patterns printed on the initial polymer film were compared with the experimental data. The proposed methodology to couple film forming analysis with injection molding analysis can be used to predict the deformation of film in IMD process.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.5
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• pp.218-227
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• 2021

A thick film NTC thermistor for low temperature co-firing was manufactured by printing and sintering a paste prepared using NTC powder of Mn_1.5Ni_0.4Co_0.9Cu_0.4O₄ composition, lead free frit, and RuO₂ on a 96 % alumina substrate. The effect of frit and RuO₂ on the electrical properties of thick film NTC thermistor was studied. The resistance of the thick film NTC thermistor was higher than that of the bulk phase sintered at the same temperature, but it was found that the negative resistance temperature characteristic appeared more clearly and linearly in the resistance - temperature characteristic. On the other hand, the area resistance decreased as the sintering temperature increased, and the area resistance increased as the amount of frit added increased. The B constant of the thick film NTC thermistor was 3000 K or higher. Among them, it was found that the B constant of the thick film NTC thermistor made of paste with 5 wt% of frit added and sintered at 900℃ showed the highest B constant. Also, it can be seen that the area resistance decreased with the addition of RuO₂, and the change in the area resistance decrease of the thick film NTC thermistor obtained by sintering the paste containing 5 wt% of RuO₂ at 900℃ is the most obvious.

• Journal of the Korean Ceramic Society
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• v.40 no.2
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• pp.153-158
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• 2003

Self-patterning of thin films using photosensitive sol solution has advantages such as simple manufacturing process compared to photoresist/dry etching process. In this study,$La_{0.5}SR_{0.5}CoO_3$(LSCO) thin films as an electrode material for ferroelectric memories have been prepared by spin coating method using photosensitive sol solution. La-2methoxyethoxide, Sr-ethoxide, Co-2methoxyethoxide were used as starting materials. As UV exposure time to the LSCO gel thin film increased, the UV absorption peak intensity of metal${beta}$-diketonate decreased due to reduced solubility by M(metal)-O-M bond formation. Solubility difference by UV irradiation on LSCO gel thin film allows to obtain a fine patterning of thin film. The LSCO thin films annealed over$680{\circ}C$ in air showed perovskite phase and the lowest resistivity$(4{ imes}10^{-3}{Omega}cm)$ of the thin films were obtained by annealing at$740{\circ}C$.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.4 s.37
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• pp.359-363
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• 2005

The organic insulation devices with MIM (metal-insulator-metal) structures as PVP gate insulation films were prepared for the application of organic thin film transistors (OTFT). The co-polymer organic insulation films were synthesized by using PVP(poly-4-vinylphenol) as solute and PGMEA (propylene glycol monomethyl ether acetate) as solvent. The cross-linked PVP insulation films were also prepared by addition of poly (melamine-co-formaldehyde) as thermal hardener. The leakage current of the cross-linked PVP films was found to be about 300 pA with low current noise. and showed better property in electrical properties as compared with the co-polymer PVP insulation films. In addition, cross-linked PVP insulation films showed better surface morphology (roughness), showing about 0.11${\~}$0.18 nF in capacitance for all PVP film samples.

• Journal of the Korean Electrochemical Society
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• v.8 no.1
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• pp.37-41
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• 2005

We investigated the electrochemical properties and microstructure on the various argon deposition pressure $(P_{Ar})$ and the low annealing temperature $(400^{\circ}C)$ of $LiCoO_2$ cathodes, which deposited by R.F. magnetron sputtering. The microsuucture and composition of Lico02 thin film was changed as a function of $P_{Ar}$. The capacity and electrochemical properties were improved with Ph of $LiCoO_2$ thin films. The cycling reversibility and stability of thin film batteries were measured by cyclic voltammetry and the constant current charge-discharge. The physical properties of cathode films were analyzed by ICP-AES, XRD, SEM and AFM for composition, crystallization and surface morphology.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.145.2-145.2
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• 2016

We report the phase transformation of Co thin films on a sapphire substrate induced by laser irradiation. As grown Co films were initially strained and tetragonally distorted. With low power laser irradiation, the surface was ruptured and irregular holes were formed. As the laser power was increased, the films changed into round shape Co nanocrystals with well-defined 6-fold structure. By measuring the XRD of Co nanostructure as a function of laser energy densities, we found that the change of morphological shapes from films to nanocrystals was accompanied with decrease of the tetragonal distortion as well as strain relaxation. By measuring the size distribution of nanocrystals as a function of film thickness, the average diameter is proportional to 1.7 power of the film thickness which was consistent with the prediction of thin film hydrodynamic (TFT) dwetting theory. Finally, we fabricated the formation of size controlling nanocrystals on the sapphire substrate without strain.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.7
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• pp.539-545
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• 2001

Undoped and Co$^{2+}$ $\alpha$-Ga$_2$S$_3$ thin films were grown by spray pyrolysis method. It has been found that these thin films have a monoclinic structure and direct optical energy gap and indirect were located to 3.477eV and 3.123 eV at 10K respectively. In the photoluminescence due to a D0A(donor-acceptor) pair recombination were observed at 502 nm and 671 nm for the $\alpha$-Ga$_2$S$_3$ thin film, where is excited by the 325 nm-line of He-Cd laser. These peaks are identified to be corresponding to the electron transition between the energy levels of Co$^{2+}$ ion sited a the T$_{d}$ symmetry point in the $\alpha$-Ga$_2$S$_3$;Co$^{2+}$ thin film. film.

• Current Photovoltaic Research
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• v.3 no.1
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• pp.1-4
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• 2015

In this study, we analyzed the correlation between mechanical and electrical properties of low-temperature conductive film (LT-CF) bonded silicon solar cells by a quadrant analysis (horizontal axis (peeling strength), vertical axis (power loss)). We found that a series of points with various bonding parameters such as bonding temperature, pressure and time were distributed in the different three regimes; weak regime (Q2: weak bonding strength and high power loss), moderate regime (Q4 : strong bonding strength and low power loss) and hard regime (Q3 : weak bonding strength and low power loss). Using this analogous technique, it was possible to fabricate the LT-CF bonded silicon solar cells with the various conditions displayed in Q3 of the quadrant plots, possessing the peeling strength of ~ 1N/mm and power loss of 2~3%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.106-106
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• 2009

Al-doped ZnO (AZO) thin films were grown on glass substrates by co-sputtering at room temperature. We made ZnO and Al target and ZnO:Al film is deposited with sputter which has two RF gun source. The Al content was controlled by varying Al RF power and effect of Al contents on the properties of ZnO:Al film was investigated. Crystallinity and orientation of the ZnO:Al films were investigated by X-ray diffraction (XRD), surface morphology of the ZnO:Al films was observed by atomic force microscope. Electrical properties of the ZnO:Al films were measured at room temperature by van der Pauw method and hall measurement. Optrical properties of ZnO:Al films were measured by UV-vis-NIR spectrometer.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.245-248
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• 1991

Recently, oxide semiconductor gas sensors consisted of n-type semiconductor materials such as $SnO_2$, ZnO and $Fe_2O_3$ have been widely used to detect reducing gases. In this paper, we made the thick-film ZnO gas sensors with $PdCl_2$ as a catalyst and investigated the sensitivity to CO gas. In the thick-film Zno sensor, the highest sensitivity was shown in the sensor with 1wt.% of $PdCl_2$ which was sintered for 1 hour at $700^{\circ}C$ and operated at $300^{\circ}C$.