• Archives of Pharmacal Research
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• v.26 no.7
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• pp.569-574
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• 2003

Controlled-release amitriptyline pellets (ATP) were formulated and its oral bioavailability was assessed in human volunteers after oral administration under fasting conditions. Core pellets were prepared using a CF granulator by two different methods (powder layering and solvent spraying) and coated with Eudragit RS or RL 100. Physical characteristics and dissolution rates of core pellets and coated pellets were evaluated to optimize the formulation. Powder layering method resulted in a better surface morphology than solvent spraying method. However, physical properties of the products were poorer when prepared by powder layering method with respect to hardness, friability and density. The dissolution profile of amitriptyline coated with Eudragit RS 100 was comparable to that of commercially available amitriptyline enteric-coated pellets ($Saroten^{\circledR}$ retard). After the oral administration of both products at the dose of 50 mg, the mean maximum concentrations ($C_{max}$) were 36.4 and 29.7 ng/mL, and the mean areas under the concentration-time curve ($AUC_{0-96}$) were 1180.2 and 1010.7 ng.h/mL for ATP and Saroten retard, respectively. The time to reach the maximum concentrations ($T_{max}$) was 6 h for both formulations. Statistical evaluation suggested that ATP was bioequivalent to Saroten retard.

• Tribology and Lubricants
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• v.23 no.6
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• pp.261-265
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• 2007

Carbide-derived carbon coating has been synthesized by low temperature treatment of TiC disk with $H_2/Cl_2$ mixture gases. A variety of physical measurements indicated that Ti was extracted and carbon layer was formed by exposure of $Cl_2$ gas. The $I_D/I_G$ ratio increased with increasing $Cl_2$ gas concentration. Wear coefficient and frictional coefficient varied with $Cl_2$ gas concentration. When the $Cl_2$ gas concentration decreased to 3.3 vol%, the friction coefficient approach a minimum. The results showed that degree of graphite crystallinity and variation of porosity due to the $Cl_2$ gas content were responsible for different tribology performance.

• Journal of Sensor Science and Technology
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• v.15 no.2
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• pp.148-152
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• 2006

This paper describes the fabrication of SiCN microstructures for super-high temperature MEMS using photopolymerization of pre-ceramic polymer. In this work, polysilazane liquide as a precursor was deposited on Si wafers by spin coating, microstructured and solidificated by UV lithography, and removed from the substrate. The resulting solid polymer microstructures were cross-linked under HIP process and pyrolyzed to form a ceramic of withstanding over $1400^{\circ}C$. Finally, the fabricated SiCN microstructures were annealed at $1400^{\circ}C$ in a nitrogen atmosphere. Mechanical characteristics of the SiCN microstructure with different fabrication process conditions were evaluated. The elastic modules, hardness and tensile strength of the SiC microstructure implemented under optimum process condtions are 94.5 GPa, 10.5 GPa and 11.7 N/min, respectively. Consequently, the SiCN microstructure proposed in this work is very suitable for super-high temperature MEMS application due to very simple fabrication process and the potential possiblity of sophisticated mulitlayer or 3D microstructures as well as its good mechanical properties.

• Journal of the Korean Ceramic Society
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• v.51 no.5
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• pp.481-486
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• 2014

Environmental barrier coatings (EBCs) are used to protect SiC-based ceramics or composites from oxidation and corrosion due to reaction with oxygen and water vapour at high temperatures above $1000^{\circ}C$. Mullite ceramics have been studied for environmental barrier coatings for Si-based ceramics. More recently, rare earth silicate ceramics have been identified as more water vapour-resistant materials than mullite for environmental barrier coatings. In this study, we fabricate mullite and yttrium silicate ceramics by an atmospheric plasma spray coating method using spherical granules fabricated by spray drying. As a result, EBCs with thicknesses in the range of $200-300{\mu}m$ are successfully fabricated without any macroscopic cracks or interfacial delamination. Phase and microstructure analysis are conducted, and the basic mechanical properties, such as hardness and indentation load-displacement curves are evaluated.

• Transactions on Electrical and Electronic Materials
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• v.13 no.2
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• pp.64-68
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• 2012

We have successfully demonstrated a bandgap alteration of transparent zinc oxide (ZnO) thin film with Mg dopant by using sol-gel spin coating technique. By increasing the dopant from 0 to 30 atomic percent (at.%), a decrement value in the cutoff is observed, where the absorption edge shifts continuously to the shorter wavelength side, towards 300 nm. This resulted in a significant bandgap increment from 3.28 to 3.57 eV. However, the transmittance of the thin film at 350-800 nm gradually downgraded, from 93 to 80 % which is most probably due to the grain size that becomes bigger, and it also affected the electrical properties. The decrement from 45 to 0.05 mA at +10 V was observed in the I-V characteristics, concluding the significant relationship; where higher optical bandgap materials will exhibit lower conductivity. These findings may be useful in optoelectronics devices.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2529-2534
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• 2012

Poly(3,4-ethylenedioxythiophene) coated Manganese Dioxide (PEDOT/$MnO_2$) composite electrode was fabricated by simply immersing the $MnO_2$ electrode in an acidic aqueous solution containing 3,4-ethylenedioxythiophene (EDOT) monomers. Analysis of open-circuit potential of the $MnO_2$ electrode in the solution indicates the reduction of outer surface of $MnO_2$ to dissolved $Mn^{2+}$ ions and simultaneously oxidation of EDOT monomer to PEDOT on the $MnO_2$ surface to form a PEDOT shell via a galvanic displacement reaction. Analysis of cyclic voltammograms and specific capacitance of the PEDOT/$MnO_2$, conductive carbon added $MnO_2$ and conductive carbon added PEDOT/$MnO_2$ electrodes suggests that the conductive carbon acted mainly to provide a continuous conducting path in the electrode to improve the rate capability and the PEDOT layer on $MnO_2$ acts to increase the active reaction site of $MnO_2$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.1
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• pp.36-40
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• 2003

The diamond-like nanocomposite (DLN) thin films were deposited on Si substrates using $CH_4/(C_2H_5O)_4Si/H_2$/Ar gas mixtures as source gases by the plasma enhanced chemical vapor deposition (PECVD). The chemical structure and microstructure of grown films were investigated and their tribological properties were evaluated by a ball-on-plate type tribometer. The deposited DLN films mainly consisted of diamond-like a-C:H and quartz-like a-Si:O networks. The DLN films had a good agreement with tribological coating applications due to their extremely low friction coefficients and low wear rates.

• Geomechanics and Engineering
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• v.13 no.1
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• pp.99-117
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• 2017

Rock physics modeling of sandstone reservoir from gas fields of Krishna-Godavari basin represents the link between reservoir parameters and seismic properties. The rock physics diagnostic models such as contact cement, constant cement and friable sand are chosen to characterize reservoir sands of two wells in this basin. Cementation is affected by the grain sorting and cement coating on the surface of the grain. The models show that the reservoir sands in two wells under examination have varying cementation from 2 to more than 6%. Distinct and separate velocity-porosity and elastic moduli-porosity trends are observed for reservoir zones of two wells. A methodology is adopted for generation of Rock Physics Template (RPT) based on fluid replacement modeling for Raghavapuram Shale and Gollapalli Sandstones of Early Cretaceous. The ratio of P-wave velocity to S-wave velocity (Vp/Vs) and P-impedance template, generated for this above formations is able to detect shale, brine sand and gas sand with varying water saturation and porosity from wells in the Endamuru and Suryaraopeta gas fields having same shallow marine depositional characters. This RPT predicted detection of water and gas sands are matched well with conventional neutron-density cross plot analysis.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.363.2-363.2
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• 2016

Stretchable strain sensors are becoming essential in diverse future applications, such as human motion detection, soft robotics, and various biomedical devices. One of the well-known approaches for fabricating stretchable strain sensors is to embed conductive nanomaterials such as metal nanowires/nanoparticles, graphene, conducting polymer and carbon nanotubes (CNTs) within an elastomeric substrate. Among various conducting nanomaterials, CNTs have been considered as important and promising candidate materials for stretchable strain sensors owing to their high electrical conductivity and excellent mechanical properties. In the past decades, CNT-based strain sensors with high stretchability or sensitivity have been developed. However, CNT-based strain sensors which show both high stretchability and sensitivity have not been reported. Herein, highly stretchable and sensitive strain sensors were fabricated by integrating single-walled carbon nanotubes (SWNTs) and nylon textiles via vacuum-assisted spray-layer-by-layer process. Our strain sensors had high sensitivity with 100 % tensile strain (gauge factor ~ 100). Cyclic tests confirmed that our strain sensors showed very robust and reliable characteristic. Moreover, our SWNTs-based strain sensors were easily and successfully integrated on human finger and knee to detect bending and walking motion. Our approach presented here might be route to preparing highly stretchable and sensitive strain sensors with providing new opportunity to realize practical wearable devices.

• Journal of Surface Science and Engineering
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• v.50 no.3
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• pp.177-182
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• 2017

The properties of electroless Ni-B thin film on diamond powder with different parameters (temperature, pH, surfactant etc.) were studied. The surface morphology, structure and composition distribution of the Ni-B film were observed by field effect scanning electron microscope (FE-SEM), energy-dispersive spectrometer (EDS), X-ray diffraction (XRD) and Auger electron spectroscopy (AES). The growth rate of Ni-B film was increased with increase of bath temperature. The B content in Ni-B film was reduced with increase of bath pH. As a result the structure of Ni-B film was changed from amorphous to crystalline structure. The PVP in solution plays multi-functional roles as a dispersant and a stabilizer. The Ni-B film deposited with adding 0.1 mM-PVP was strongly introduced an amorphous structure with higher B content (25 at.%). Also the crystallite size of Ni-B film was reduced from 12.7 nm to 5.4 nm.