• Korean Journal of Mineralogy and Petrology
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• v.36 no.2
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• pp.107-115
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• 2023

Cobalt can be released into the natural environment as industrial waste from the alloying industry and as acid mine drainage, and it is also a radionuclide (⁶⁰Co) that constitutes high-level radioactive waste. Smectite is a mineral that can be useful for adsorption and isolation of this element. In this study, Cheto-type montmorillonite (Cheto-MM), which is the source clays of The Clay Mineral Society (CMS) and already well-characterized, was used. The effect of the adsorption site affected by the presence of interlayer water on the adsorption of cobalt before and after dehydration by heating was evaluated and the adsorption mechanism of cobalt on Cheto-MM was studied by applying adsorption kinetics and adsorption isotherm models. The results showed that the adsorption characteristics changed with dehydration and subsequent shrinkage, and cobalt was found to be adsorbed at the edge of Cheto-MM for about 38% and adsorbed at the interlayer site for about 62%, suggesting that the cobalt adsorption of Cheto-MM is significantly influenced by the interlayer. By applying the adsorption kinetic models, the cobalt adsorption kinetics of Cheto-MM is explained by a pseudo-second-order model, and the concentration-dependent adsorption was best described by the Langmuir isotherm adsorption model. This study provides basic knowledge on the adsorption characteristic of cobalt on montmorillonite with different adsorption sites and is expected to be useful in predicting the adsorption behavior of smectite in high-level radioactive waste disposal sites in the future.

• Korean Journal of Soil Science and Fertilizer
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• v.27 no.3
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• pp.158-167
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• 1994

The various weathering products derived from andesitic rocks in the Guweol mountain area of Pusan have been studied in order to investigate the occurrence, characteristics and evolutional trend of clay minerals in the weathered rock and soil using mainly X-ray powder diffraction method. Kaolinite and halloysite are very abundant in the weathered rocks and soils derived from andesitic rocks of this area. Also, $12{\AA}$- and $14{\AA}$-minerals occur in the considerable amount. $12{\AA}$-minerals have been identified as mica/vermiculite interlayer minerals showing the $25{\AA}$ basal reflection. Their crystal sizes are relatively big showing more than 10 micron in diameter. Two types of $14{\AA}$-mineral, which are vermiculite/smectite interlayer mineral and Al-vermiculite, have been observed. Kaolin minerais consist of kaolinite, $10{\AA}$ and $7{\AA}$ halloysite. Kaolinite relatively dominates in the strongly weathered soil of the area. In contrast with kaolinite. $12{\AA}$- and $14{\AA}$-minerals such as vermiculite/smectite and mica/vermiculite interlayer minerals tend to occur in the weakly to intermediately weathered products. Based on their occurrences, it strongly suggests that they are intermediate products in the course of the weathering process from the parent materials into the kaolin mineral.

• Journal of the Semiconductor & Display Technology
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• v.8 no.3
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• pp.19-23
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• 2009

We have studied dielectric characteristics of low-k interlayer dielectric materials was fabricated by plasma enhanced chemical vapor deposition (PECVD). BTMSM precursor was introduced with the flow rates from 24 sccm to 32 sccm by 2 sccm step in the constant flow rate of 60 sccm $O_2$. Then, SiOCH thin film deposited at room temperature was annealed at temperature of $400^{\circ}C$ and $500^{\circ}C$ for 30 minutes in vacuum. The vibrational groups of SiOCH thin films were analyzed by FT/IR absorption lines, and the dielectric constant of the low-k SiOCH thin films were obtained by measuring C-V characteristic curves. With the result that FTIR analysis, as BTMSM flow rate increase, relative carbon content of SiOCH thin film increased from 29.5% to 32.2%, and increased by 32.8% in 26 sccm specimen after $500^{\circ}C$ annealing. Dielectric constant was lowest by 2.32 in 26 sccm specimen, and decreased more by 2.05 after $500^{\circ}C$ annealing. Also, leakage current is lowest by $8.7{\times}10^{-9}A/cm^2$ in this specimen. In the result, shift phenomenon of chemical bond appeared in SiOCH thin film that BTMSM flow rate is deposited by 26 sccms, and relative carbon content was highest in this specimen and dielectric constant also was lowest value

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.158-162
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• 1995

We report rf and power characteristics of AlGaAs/GaAs Heterojunction Bipolar Transistor (HBTs) for X-band power applications. HBTs have been fabricated with polyimide a an interlayer dielectric. By characterizing the DC and RF characteristics we obtained the maximum current gain of 45, BV$\_$CEO/ of 10 V, fT of 30 GHz and f$\_$max/ of 17 GHz for device with 6x14$\mu\textrm{m}$$^2$emitter size. To extract accurate equivalent parameters, the De-embedded method was applied for extraction of parasitic parameters and the calculation of circuit equations for intrinsic parameters. Based on the Load-pull method, power characteristics was simulated and measured to get the maximum output power of the device.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.10a
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• pp.248-253
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• 1998

Recently, the uses of Ceramic/metal bonded joints, resin/metal joints, adhesive joints, composite materials which are composed of dissimiliar materials have increased in various industry fields. Since the ceramic/metal bonded joints material is made at a high temperature, residual stress distributions due to differences in material properties were investigated by varying material parameters. The two dimensional finite element analysis was performed to study residual stress distribution in Si3N4/SM45C bonded joint with a copper interlayer between the silicon nitride(Si3N4) and the structural carbon steel(SM45C) and 4-point bending tests were carried out under room temperature. Fracture surface and crack propagation path were observed using scanning electron microscope and characteristics of its fracture was discussed.

• KSTLE International Journal
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• v.9 no.1_2
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• pp.31-35
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• 2008

DLC (Diamond Like Carbon) films have predominant tribological properties like a high hardness, low friction and high chemical resistance; therefore, DLC films are applied in a wide range of industrial fields. This paper evaluated the characteristics of DLC films deposited on bearing steel with different hardness by RF-PECVD (Radio Frequency - Plasma Enhanced Chemical Vapor Deposition) method. Si-interlayer was deposited on bearing steel to improve adhesion strength by RF-Sputtering method. The DLC film structures were analyzed with Raman spectra and Gaussian function. Adhesion strength of DLC films was measured with a scratch tester. Friction and wear test were carried out with a ball-on -disc type to investigate the tribological characteristics. Experimental results showed that DLC films deposited on bearing steel under same deposition condition have typical structure DLC films regardless of hardness of bearing steel. Adhesion strength of DLC film is increased with a hardness of bearing steel. Friction coefficient of DLC film showed lower at the high hardness of bearing steel.

• Journal of the Korean Vacuum Society
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• v.8 no.3B
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• pp.340-345
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• 1999

In this paper, polyimide thin films are fabricated by vapor deposition polymerization method appling to the interlayer insulator of semiconductor device, and are investigated in detail. It is found that the packing density and uniformity of films deposited by thermal evaporation are increased according to curing temperature. The resistivity, breakdown strength, relative permitivity, and dielectric loss are $3.2\tomes10^{15}\Omega$cm, 4.61 MV/cm, 2.9(10kHz) at $25^{\circ}C$, respectively. This thin films can be endured at $230^{\circ}C$ for 20,000 hours. Finally, we conclude that the thin films having the characteristics similar to those of $SiO_2$ can be used as an insulation films between layers of semiconductor device.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1509-1511
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• 2001

In this study, etching characteristics of polyimide(Pl) film with $O_2/CF_4$ gas mixing ratio was studied using inductively coupled plasma (ICP). The etch rate and selectivity were evaluated to chamber pressure and gas mixing ratio. High etch rate (over 8000$\AA$/min) and vertical profile were acquired in $CF_4$/($CF_4+O_2$) of 0.2. The selectivities of polyimide to PR and polyimide to $SiO_2$ were 1.15, 5.85, respectively. The profiles of polyimide film etched in $CF_4/O_2$ were measured by a scanning electron microscope (SEM) with using an aluminum hard mask pattern. The chemical states on the polyimide film surface were measured by x-ray photoelectron spectroscopy (XPS).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.4
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• pp.362-367
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• 2008

We have Manufactured the low-k dielectric interlayer fabricated by plasma enhanced chemical vapor deposition (PECVD), The thin film of SiOCH is studied correlation between components and Dielectric constant. The precursor was evaporated and introduced with the flow rates from 16 sccm to 25 sccm by 1sccm step in the constant flow rate of 60 sccm $O_2$ in process chamber. The chemical characteristics of SiOCH were analyzed by measuring FT/IR absorption lines and obtained each dielectric constant measuring C-V. Then compare respectively. ILD of BTMSM/$O_2$ could have low dielectric constant about $k\sim2$, and react sensitively. Also dielectric constant could be decreased by the effects of decreasing $CH_3$ and growing Si-O-Si(C) after annealing process.

• Journal of the Korean Ceramic Society
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• v.43 no.4 s.287
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• pp.247-252
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• 2006

Joining Yittria Stabilized Zirconia (YSZ) to NiCr metal was fabricated using YSZ/NiCr Functionally Graded Materials (FGM) Interlayer by hot pressing process. Microscopic observations demonstrate that the composition and microstructure of YSZ/NiCr FGM distribute gradually in stepwise way, eliminating the macroscopic ceramic/metal interface such as that in traditional ceramic/metal joint. The thermal characteristics of this YSZ/FGM/NiCr joint were studied by thermal shock testing and therml barrier testing. Thermal shock test was conducted by gas burner rig. Acoustic Emission (AE) monitoring was performed to analyze the microfracture behavior during the thermal shock test. It could be confirmed that FGM was the excellent performance of thermal shock/barrier resistance at above $1000^{\circ}C$.