• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.2
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• pp.112-117
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• 2008

Vertical interconnection scheme using novel silicon-through-via for 3D MEMS devices or stacked package is proposed and fabricated to demonstrate its feasibility. The suggested silicon-through-via replaces electroplated copper, which is used as an interconnecting material in conventional through-via, with doped silicon. Adoption of doped silicon instead of metal eliminates thermal-mismatch-induced stress, which can make troubles in high temperature MEMS processes, such as wafer bonding and LP-CVD(low pressure chemical vapor deposition). Two silicon layers of $30{\mu}m$ thickness are stacked on the substrate. The through-via arrays with spacing $40{\mu}m$ and $50{\mu}m$ are fabricated successfully. Electrical characteristics of the through-via are measured and analyzed. The measured resistance of the silicon-through-via is $169.9\Omega$.

• Wind and Structures
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• v.26 no.2
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• pp.75-87
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• 2018

A large number of low-rise buildings experienced serious roof covering failures under strong wind while few suffered structural damage. Clay and concrete tiles are two main kinds of roof covering. For the tile roof system, few researches were carried out based on Finite Element (FE) analysis due to the difficulty in the simulation of the interface between the tiles and the roof sheathing (the bonding materials, foam or mortar). In this paper, the FE analysis of a single clay or concrete tile with foam-set or mortar-set were built with the interface simulated by the equivalent nonlinear springs based on the mechanical uplift and displacement tests, and they were expanded into the whole roof. A detailed wind tunnel test was carried out at Tongji University to acquire the wind loads on these two kinds of roof tiles, and then the test data were fed into the FE analysis. For the purpose of validation and calibration, the results of FE analysis were compared with the full-scale performance ofthe tile roofs under simulated strong wind impact through one-of-a-kind Wall of Wind (WoW) apparatus at Florida International University. The results are consistent with the WoW test that the roof of concrete tiles with mortar-set provided the highest resistance, and the material defects or improper construction practices are the key factors to induce the roof tiles' failure. Meanwhile, the staggered setting of concrete tiles would help develop an interlocking mechanism between the tiles and increase their resistance.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.2
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• pp.210-216
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• 2002

Air abrasion technology can prepare enamel and dentin for bonding, similar to etching by acidic gels and solutions. Longer treatment can excavate pit and fissures, preparing the tooth for immediate placement of bonded resin materials. Although not appropriate for every clinical situation, the air abrasive technology minimizes heat, vibration and bone-conducted noise associated with conventional means of caries removal since the cutting is accomplished by air pressure. Also, patients treated with the air-abrasion technology rarely request anesthesia. Air abrasion technology was more effective in treating early carious lesions and stains compared to lesions where caries had already progressed to produce soft dentin and the strong air stream and noise caused by the evacuation system was a major discomfort to pediatric patients, and the experience and skillfulness of clinician should be required for accurate and proper tooth preparation.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.3
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• pp.199-206
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• 2012

HC-SCR was conducted over Co-Pt/ZSM5 catalyst coated over 200 cpsi cordierite in the condition of atomspheric pressure and $200^{\circ}C-500^{\circ}C$. Weight ratio of Co/Pt determined from EDX analysis was 8/2, which was almost equal to the weight ratio at preparation step. XPS showed that nitrates within cobalt precursor and chlorine withn Pt precursor were removed. TEM result demonstrated that crystallite size of cobalt and Pt was under 5nm. Among these tested hydrocarbon reductants, isobutane ($i-C_4H_{10}$) showed the highest de-$NO_x$ yield of 80% under the condition of the mole ratio of reductant/NOx=1.0 at $180^{\circ}C$. De-$NO_x$ yield from HC-SCR was increased as the carbon number of hydrocarbon reductant was increased. The decrease of bonding energy between C and H of HC reductant played a role to increase of de-$NO_x$ yield, which indicated that the dissociation step of C-H bond of hydrocarbon molecule might be the rate determining step of HC-SCR. The increase of oxygen concentration in the feed resulted in the decrease of de-$NO_x$ yield but the increase of CO and $N_2O$ yield.

• The Journal of the Convergence on Culture Technology
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• v.6 no.1
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• pp.477-483
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• 2020

The rehabilitation methods used in existing concrete box structures rely on the method of attaching the repair material to the section of the structure with a spray equipment. In the case of ceiling or wall parts, the adhesion force to the repair material may be reduced by the gravity and dead load after construction. In subway structures, vibration causes a problem that reduces the initial adhesion. Supplementary measures are needed as the quality of repair varies depending on the worker's proficiency and construction environment. In this study, mechanical pressurization equipment was developed that can apply a certain pressure after construction of a repairwork to solve problems such as reduction of adhesion of repair materials by gravity and variation of repair quality by labor work. To find out the effect of the pressurized equipment, a chamber similar to the field conditions was constructed to measure the attachment strength different from the pressurized condition, the section, and the environmental conditions. The pressurization differed from the other parts, but the adhesion strength of up to 70% was increased.

• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.232-243
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• 2010

Gas hydrates are crystalline solids composed of water and gas molecules. Water molecules are linked through hydrogen bonding and create cavities(host lattice) that can capture a large variety of guest molecules under appropriate conditions, generally high pressure and low temperature. Recently, many researchers try to apply gas hydrates to industrial processes to capture greenhouse gases due to the facts that the process is eco-friendly and target gas molecules can be preferentially captured. In this paper, we introduced recent studies on $CO_2$ and $CO_2-N_2$ mixture hydrates to evaluate the feasibility of industrial application of gas hydrate technology to $CO_2$ capture process. Specifically, we put emphasis on the technical feasibility of $CO_2$ separation in steel industry using gas hydrate formation principles.

• Korean Journal of Metals and Materials
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• v.50 no.8
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• pp.569-573
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• 2012

In order to understand the difference in SiC deposition between the $CH_3SiCl_3-H_2$ and $C_3H_8-SiCl_4-H_2$ systems, we calculate the phase stability among ${\beta}$-SiC, graphite and silicon. We constructed the phase-diagram of ${\beta}$-SiC over graphite and silicon via computational thermodynamic calculation considering pressure (P), temperature (T) and gas composition (C) as variables. Both P-T-C diagrams showed a very steep phase boundary between the SiC+C and SiC region perpendicular to the H/Si axis, and also showed an SiC+Si region with a H/Si value of up to 6700 in the $C_3H_8-SiCl_4-H_2$, and 5000 in the $CH_3SiCl_3-H_2$ system. This difference in phase boundaries is explained by the ratio of Cl to Si, which is 4 for the $C_3H_8-SiCl_4-H_2$ system and 3 for the $C_3H_8-SiCl_4-H_2$ system. Because the C/Si ratio is fixed at 1 in the $CH_3SiCl_3-H_2$ system while it can be variable in the $C_3H_8-SiCl_4-H_2$ system, the functionally graded material is applicable for better mechanical bonding during SiC coating on graphite substrate in the $C_3H_8-SiCl_4-H_2$ system.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.3
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• pp.51-57
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• 2019

To protect the Cu surface from oxidation in air, a two-step plasma process using Ar and $N_2$ gases was studied to form a copper nitride passivation as an anti-oxidant layer. The Ar plasma removes contaminants on the Cu surface and it activates the surface to facilitate the reaction of copper and nitrogen atoms in the next $N_2$ plasma process. This study investigated the effect of Ar plasma on the formation of copper nitride passivation on Cu surface during the two-step plasma process through the full factorial design of experiment (DOE) method. According to XPS analysis, when using low RF power and pressure in the Ar plasma process, the peak area of copper oxides decreased while the peak area of copper nitrides increased. The main effect of copper nitride formation in Ar plasma process was RF power, and there was little interaction between plasma process parameters.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.6
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• pp.100-107
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• 2021

As a significant technology in the smartization era promoted by the Fourth Industrial Revolution, the secondary battery industry has recently attracted significant attention. The demand for lithium-ion batteries (LIBs), which exhibit excellent performance, is considerably increasing in different industrial fields. During the manufacturing process of LIBs, it is necessary to join the cathode and anode sheets with thicknesses of several tens of micrometers to lead taps of the cathode and anode with thicknesses of several hundreds of micrometers. Ultrasonic welding exhibits excellent bonding when bonded with very thin plates, such as negative and positive electrodes of LIBs, and dissimilar and highly conductive materials. In addition, ultrasonic welding has a small heat-affected zone. In LIBs, Cu is mainly used as the negative electrode sheet, whereas Cu or Ni is used as the negative electrode tab. In this study, one or two electrode sheets (t0.025 mm Cu) were welded to one lead tab (t0.1 mm Cu). The welding energy and pressure were used as welding parameters to determine the welding strength of the interface between two or three welded materials. Finally, the effects of these welding parameters on the welding strength were investigated.

• Korean Chemical Engineering Research
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• v.60 no.2
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• pp.237-242
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• 2022

In this study, a drying method that can effectively remove residual solvent from (+)-dihydromyricetin was developed. Residual acetone concentration was efficiently removed below ICH-specified value (5,000 ppm) by simple rotary evaporation with ethanol pretreatment. In addition, the residual ethanol met the ICH-specified value (5,000 ppm) by simple rotary evaporation through the addition of water, and the residual moisture also met the specified value (<4%) for active pharmaceutical ingredients. At all the drying temperature (35, 45, and 55 ℃), a large amount of the residual solvent was initially removed during the drying, and the drying efficiency increased when increasing the drying temperature. Removal of residual solvent by ethanol pretreatment was shown to be related to high vapor pressure of acetone-ethanol mixture and hydrogen bonding between acetone and ethanol.