• Journal of the Korean Ceramic Society
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• v.53 no.4
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• pp.411-416
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• 2016

Benzothienobenzothiophene ($C_8-BTBT$) is a soluble organic small molecule material with high crystallinity resulting from its strong self-organizing properties. In addition, the high mobility and easy fabrication of $C_8-BTBT$ make it very attractive in terms of organic thin-film transistors. In this work, we made $C_8-BTBT$ thin films by using the zone-casting method; we also used an organic solvent to treat the devices with solvent vapor annealing to improve the electrical properties. As a result, we confirmed improved mobility, threshold voltage, and subthreshold swing after solvent vapor annealing. To prove the effect of solvent vapor annealing, we used the simultaneous extraction model to extract the contact resistance from the current-voltage curve. We confirmed that the electrical properties improved with decreasing contact resistance.

• Journal of Korea Foundry Society
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• v.27 no.2
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• pp.88-94
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• 2007

General criteria for the risering design of steel castings and commercial codes for the flow and solidification analysis were used to design the optimized risering in V-process. Three type of specimens were chosen including thin plates and a thick disc. Sided riser installed in the front of a plate casting was effective to prevent the shrinkage defects and to increase the casting yield ratio. Exothennic sleeve and chill were also effective. It was possible to apply the general criteria for the risering design of steel castings to V-process. Temperature of a mold surface was expected to rise over $1,000^{\circ}C$ in the temperature calculation considering radiation effect of molten metal in the mold. Since weakening temperature of the vinyl used in V-process is about $70^{\circ}C$, it should be emphasized that a proper coating of the vinyl film is necessary to prevent the possibility of burning out of the vinyl by the molten metal.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.2
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• pp.241-246
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• 2013

This paper reports fabrication and characterization of cellulose Electro-Active Paper (EAPap) with increased thickness. Usual thickness of cellulose EAPap was $15{\mu}m$. This thickness needs to be increased to enhance the mechanical force output of EAPap. To fabricate thick cellulose EAPap, the fabrication process parameters including casting and drying processes should be investigated. In this paper, the casting thickness is increased from $800{\mu}m$ to $1500{\mu}m$, and heating times on a hot plate before and after curing process are introduced at 40 and $60^{\circ}C$ for 30 and 60 minutes, respectively. Thickness measurement, Thermal Gravitational Analysis (TGA), UV-transmittance, Young's modulus, and piezoelectric charge constant are measured. Heated EAPaps with increased thickness have similar TGA result, higher transmittance, higher Young's modulus and lower piezoelectric charge constant.

• Journal of Korea Foundry Society
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• v.36 no.4
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• pp.117-125
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• 2016

The effects of the Zn content on the microstructure and corrosion behavior in 1M NaCl solution were investigated in Mg-(0~6)%Zn casting alloys. The MgZn phase was scarcely observed in the Mg-1%Zn alloy, while the Mg-(2~6)%Zn alloy consisted of ${\alpha}$-(Mg) and MgZn phases. With an increase in the Zn content, the amount of the MgZn phase was gradually increased. Immersion and electrochemical corrosion tests indicated that the Mg-1%Zn alloy had the lowest corrosion rate among the alloys, and a further increase in the Zn content resulted in the deterioration of the corrosion resistance. Microstructural examinations of the corroded surfaces and EIS analyses of surface corrosion films revealed that the best corrosion resistance at 1%Zn was associated with the absence of MgZn phase particles in the microstructure and the contribution of Zn element to the formation of a protective film on the surface. A micro-galvanic effect by the MgZn particles led to the increased rate of corrosion at a higher Zn content.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.202-203
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• 2005

To recognize whether admixture affects some $(Ba_{0.6}Sr_{0.4})TiO_3$, powder in this research $Li_2CO_3$, MgO, $MnO_2$ adding each 3 wt % by Tape casting method thick film make. Sitering temperature lowered 1300$^{\circ}C$ adding $Li_2CO_3$, and density is 5.942g/$cm^3$, and specific inductive capacity increases about decuple and displayed 4000. Climbed sitering temperature 1400$^{\circ}C$ adding MgO, specific inductive capacity reduced 1/2 times. Lowered sintering temperature 1325$^{\circ}C$ low adding $MnO_2$.

• Journal of Korea Foundry Society
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• v.26 no.1
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• pp.34-39
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• 2006

In the present study, the possibility of Mg-Zn-Y alloys as high temperature casting alloys has been investigated. The fluidity of alloys containing yttrium were better than that of commercial AZ91 alloy because the oxide layer on the surface reduced the reaction between melt, and air and mold, which would reduce the resistance during the process of filling the mold. However, this oxide film reduced the hot-tearing resistance. In the case of ZAW942, this alloy exhibited fluidity and hot-tearing resistance better than AZ91 alloy. Because of thermally stable quasicrystal and other phases obstructed the movement of grains, the creep resistance of alloys containing rare earth elements more than 2 wt% was better than that of AZ91 alloy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.303-304
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• 2005

Add $Li_2CO_3$ to $(Ba_{0.6}Sr_{0.4})$ $TiO_3$ powder to lower sitering temperature in this research, made thick film by tape casting method. Investigated about sitering temperature and physical properties that added $Li_2CO_3$ Even if lower sitering temperature about $200^{\circ}C$ adding $Li_2CO_3$ 10wt.%, density was near to 5.7$g/cm^3$ that is theoretical values, and crystal structure examined as perobeuseukaiteu senior after sintering.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.12
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• pp.955-960
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• 2012

We fabricated piezoelectric unimorph cantilever generators (UCG) using $Pb(Zr_{0.54}Ti_{0.46})O_3$ + 0.2 wt% $Cr_2O_3$ + 1.0 wt% $Nb_2O_5$ (PZCN) piezoelectric thick films, which were produced by a tape casting method. The PZCN thick films were tailored with same width and thickness but different lengths from 7.7 to 57.7 mm in order to evaluate optimized UCG for energy harvesting device applications. When the length of PZCN film was increased, the resonance frequency of UCG was slightly increased from 7 Hz to 8 Hz, which could be due to enlarged area of the highly stiff piezo-ceramic film. However, the output power was proportionally increased with the length of PZCT film and it reached 4.68 mW (1.221 $mW/cm^3$) when the film's length was 57.7 mm under 25 g of tip mass at 8 Hz, which is sufficient for micro-scale device applications.

• Journal of the Korean Society of Food Science and Nutrition
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• v.13 no.1
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• pp.15-21
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• 1984

In order to ascertain the practical possibility of home made retort pouches for production of retort pouch foods in factory, two kinds of retortable pouches, i. e. 3 ply film (polyester film/Al. foil/casting polypropylene) and 4 ply film(polyester film/Al. foil/nylon/casting poll·propylene) were developed in Korea, and then, their physical properties, such as physical strength, heat resistance during thermal processing and preservability of foods and sanitary safety, were tested and compared with the foreign made pouches. The results obtained were summarized as follows. a. The physical strength of home made retort pouches in processing model foods(soybean oil 5 %, acetic acid 2%, starch 5 % and water to 100 %) was equal to that of foreign made pouches at accelerated examination condition($38^{\circ}C$, 98 % RH). But the lamination strength of home made products was a little bit superior to that of foreign made products. b. Home made retort pouches(SAMA-4 ply and SAMA-3 ply pouch) packed with rice or curry was possible to bear the thermal processing at $135^{\circ}C$ and shelf-life was one year or more at ambient temperature($20^{\circ}C$). c. Sanitary safety test showed that these home made retort pouches were acceptable comparing to the regulation recommended by the Ministry of Health and Social Affairs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.332-332
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• 2010

We have successfully demonstrated the inkjet printing method to create $Al_2O_3$ films withouWe have successfully demonstrated the inkjet printing method to create $Al_2O_3$ films without a high temperature sintering process. In order to remove the coffee ring effect in the ink drop, we have introduced a co-solvent system in order to create Marangoni flow in the ink drop, which leads to the dense packing of ceramic powders on the substrate during inkjet process. The packing density of the Inkjet-printed $Al_2O_3$ films is around 60% (max. 70%) which is very high compared to the value obtained from the same material films by other conventional methods such as film casting, dip coating process, etc. The voids inside the films (which are around 40% of the entire film volume) are filled with the polymer resin (Cyanate ester) by the infiltration process. This resin infiltration is also implemented by the inkjet printing process right after the Ah03 film ink-jetting process. The microstructures of the printed $Al_2O_3$ films are investigated by Scanning Electron Microscope (SEM) to understand the degree of packing density in the printed films. The inkjet-printed $Al_2O_3$ films have been characterized to investigate its thickness and roughness. Quality factor of the printed $Al_2O_3$ film is also measured to be over 300 at 1MHz.