• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2017년도 춘계학술대회 논문집
• /
• pp.160-160
• /
• 2017

Commercially pure titanium (Cp-Ti) and Ti alloys (typically Ti-6Al-4V) display excellent corrosion resistance and biocompatibility. Although the chemical composition and topography are considered important, the mechanical properties of the material and the loading conditions in the host have, conventionally. Ti and its alloys are not bioactive. Therefore, they do not chemically bond to the bone, whereas they physically bond with bone tissue. The electrochemical deposition process provides an effective surface for biocompatibility because large surface area can be served to cell proliferation. Plasma electrolyte oxidation (PEO) enables control in the chemical composition, porous structure, and thickness of the TiO2 layer on Ti surface. Silicon (Si) in particular has been found to be essential for normal bone and cartilage growth and development. Zinc (Zn) plays very important roles in bone formation and immune system regulation, and is also the most abundant trace element in bone. The objective of this work was to study on electrochemical behaviors of PEO-treated Ti-6Al-4V Alloy in solution containing Zn and Si ions. The morphology, the chemical composition, and the microstructure analysis of the sample were examined using FE-SEM, EDS, and XRD. The potentiodynamic polarization and AC impedance tests for corrosion behaviors were carried out in 0.9% NaCl solution at similar body temperature using a potentiostat. The promising results successfully demonstrated the immense potential of Si/Zn-TiO2 coatings in dental and biomaterials applications.

• 소성∙가공
• /
• 제8권3호
• /
• pp.259-259
• /
• 1999

TiC ceramic particulate-reinforced titanium matrix composites were fabricated and the resultant densification, microstructure, and static and dynamic mechanical properties were studied. Comparing Ti with TiH₂powders as host materials for TiC ceramic reinforcement by pressureless vacuum sintering, TiH₂-started composites showed better sinterability and resistance to both elastic and plastic deformation than Ti-started ones. When TiH₂and TiH₂-45 vol.%TiC samples were hot pressed, TiH₂matrices transformed to alpha prime Ti and alpha Ti phase, respectively. It is interpreted that the diffusion of an alpha stabilizer carbon from TiC into the matrix is one of the plausible reasons far such a microstructural difference. The 0.2% offset yield strengths of the hot pressed TiH₂and TiH₂-45 vol.%TiC samples were 1008 and 1446 MPa, respectively, in a static compressive mode (strain rate of 1×$10^{-3}$/s). Dynamic compressive strengths of the samples were 1600 and 2060 MPa, respectively, at a strain rate of 4×10³/s.

• 한국재료학회지
• /
• 제17권4호
• /
• pp.198-202
• /
• 2007

A new organic light emitting device(OLED) with two peak wavelength(blue and yellow) emission was fabricated using the selective doping in a single fluorescent host , and its electrical and optical characteristics were investigated. The fabricated device showed the luminance and efficiency of 1600 $Cd/m^2$ and 2.4 Im/W under the applied voltage of 10V, respectively. And its electroluminescent spectra had two peak wavelengths of 470nm and 560nm emitting bluish white light. The OLED with dual wavelength emission in this experiment is likely to be developed as a white OLED with simpler fluorescent system than conventional devices.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
• /
• pp.546-546
• /
• 2013

Zinc silicate ($Zn_2SiO_4$) has been identified as a suitable host material for a wide variety of luminescent activators, such as transition metal and rare earth elements. In particular, manganese-activated $Zn_2SiO_4$ exhibits highly efficient photoluminescenceand cathodoluminescence, which allows this material to be used in fluorescent lamps and display applications. In this study, we investigated the green and yellow luminescence from Mn-doped $Zn_2SiO_4$ thin films that were synthesized using radio frequency magnetron sputtering followed by annealing at $600{\sim}1,200^{\circ}C$ The refractive index of the $Zn_2SiO_4$: Mn films showed normal dispersion behavior. It was found that the $Zn_2SiO_4$: Mn films annealed at $800^{\circ}C$ ossessed a mixture of alpha and beta phases. The obtained photoluminescence spectrum consisted of two emission bands centered at 525 nm in the green range and 574 nm in the yellow range. The green luminescence originates from the divalent Mn ions in alpha phase of $Zn_2SiO_4$, while the yellow luminescence comes from the divalent Mn ions in beta phase. The films annealed at and above $900^{\circ}C$ xhibited only the alpha phase. The broad PL excitation band was observed ranging from 220 to 300 nm with a maximum at around 243 nm.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제13권1호
• /
• pp.48-57
• /
• 2013

This paper presents a power management system of the dye-sensitized solar cell (DSSC) for ubiquitous sensor network (USN) applications. The charge pump with a luminance-controlled oscillator regulates the load impedance of the DSSC to track the maximum power point (MPP) under various light intensities. The low drop-out regulator with a hysteresis comparator supplies intermittent power pulses that are wide enough for USN to communicate with a host transponder even under dim light conditions. With MPP tracking, approximately 50% more power is harvested over a wide range of light intensity. The power management system fabricated using $0.13{\mu}m$ CMOS technology works with DSSC to provide power pulses of $36{\mu}A$. The duration of pulses is almost constant around $80{\mu}s$ (6.5 nJ/pulse), while the pulse spacing is inversely proportional to the light intensity.

• E2M - 전기 전자와 첨단 소재
• /
• 제10권2호
• /
• pp.105-112
• /
• 1997

Undoped and Co$^{2+}$-doped Zn$_{4}$GeSe$_{6}$ single crystals were grown by the Chemical Transport Reaction method using iodine as a transporting agent. The crystal structure of these compounds determined by X-ray diffraction analysis was monoclinic structure. The direct energy gaps of these compounds were measured and the temperature dependence of the optical energy gap were closely investigated over the temperature range 10-290K. The temperature dependence of the optical energy gap is well presented by the Varshni equation. Also the optical absorption peaks of Zn$_{4}$GeSe$_{6}$ :Co$^{2+}$ single crystal observed, centered at 5437, 6079, 7142, 12950, 13462, 14786 and 15735 $cm^{-1}$ /, can be explained in terms of the electronic transitions of Co$^{2+}$ ions located at Td symmetry of the host materials. According to the crystal-field theory, the crystal-field, Racah and spin-orbit coupling parameters obtained from the absorption bands are given by Dq = 361$cm^{-1}$ /, B = 655$cm^{-1}$ / and .lambda. = 284$cm^{-1}$ / respectively.ively.

• International Journal of Industrial Entomology and Biomaterials
• /
• 제32권2호
• /
• pp.49-53
• /
• 2016

Bone morphogenetic proteins (BMPs) are essential growth factors for bone formation, skeletal development and bone regeneration. The BMP-2/7 heterodimer is known to have remarkable effects on osteogenic induction that are even stronger than the BMP-2 or BMP-7 homodimers. We designed a recombinant human BMP-2/7 (rhBMP-2/7) heterodimer protein with four glycine residues between BMP-2 and BMP-7 protein to facilitate free bond rotation of domains. The Baculovirus Expression Vector System (BEVS) is routinely used to produce recombinant proteins in the milligram scale. In this study, the BEVS was used to express the rhBMP-2/7 protein whrer the recombinant baculovirus was recovered in the host Sf9 cells. To confirm the biological activity of rhBMP-2/7 protein secreted from the BEVS as an osteogenic differentiation and induction factor, we measured the BMP-induced ALP activity. rhBMP-2/7 could be used as an alternative to BMPs to overcome limitations like short half-life and requirement for high concentrations. Furthermore, rhBMP-2/7 may be an efficient tool for various application studies such as bone regeneration and skeletal development.

• 대한수의학회지
• /
• 제33권4호
• /
• pp.633-647
• /
• 1993

NC strain mice were inoculated intraperitoneally with Dermatophoilus-like microorganism strain W254 isolated from the sulfur granules of the swine tonsils. The development of the resulting abscesses in NC strain mice was investigated at regular time intervals by means of histological, histochemical and electron microscopical methods. The results obtained were as follows ; 1. The inoculated bacteria have settled in the subserous site of the peritoneal organ and provoked cellular response to form neutrophil, macrophage and connective tissue layers at the time of one week after inoculation, and thereafter were found to have formed typical actinomycotic abscess two weeks after inoculation. 2. The persistant abscesses were appeared to reveal close interaction between higher activity of organism and tissue reaction and contained hyaloid bodies within or outside bacterial clumps. 3. The hyaline materials were appeared to be composed of protein rich in hydroxyphenyl group by histochemical examination. The materials were presumed to be produced by the interaction between bacterial activity and host cell reaction. 4. The bacteria in the abscesses showed the various developmental stages of coccoid body, mulberry-like body tuber-shaped body and filamentous body, and it was confirmed that the mesosomal development was related to septation of the bacterial cells.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2013년도 추계학술대회 논문집
• /
• pp.799-804
• /
• 2013

The sensor/actuator active sensor diagnostics procedure, where the sensors/actuators are confirmed to be functioning properly during operation, is a critical component to successfully complete the structural health monitoring (SHM) process with large numbers of active sensors typically installed in a structure. The basis of this process is to track the changes in the capacitive value of piezoelectric materials, which shows up in measured admittance. Due to the temperature dependent nature of piezoelectric materials, we investigated the effects of temperature variations on sensor diagnostic process. The effect of temperature variations found to be remarkable, modifying the measured capacitive values significantly. In addition we analyzed the effect of bonding agents between a PZT patch and a host structure. This paper summarizes considerations needed to develop such sensor diagnostic processes, experimental procedures and results, and additional issues that can be used as guidelines for future investigations.

• 한국소음진동공학회논문집
• /
• 제14권7호
• /
• pp.639-647
• /
• 2004

This paper concerns the analytical modeling and dynamic analysis of advanced rotating blade structure implemented by a dual approach based on structural tailoring and viscoelastic material technology. Whereas structural tailoring uses the directionality properties of advanced composite materials, the passive material technology exploits the damping capabilities of viscoelastic material (VEM) embedded into the host structure. The main structure is modeled as a composite thin-walled beam Incorporating a number of nonclassical features such as transverse shear. anisotropy of constituent materials, and rotary inertia etc. The VEM layer damping treatment is modeled by using the Golla-Hughes-McTavish (GHM) method, which is employed to account for the frequency-dependent characteristics of the VEM. The displayed numerical results provide a comprehensive picture of the synergistic implications of both techniques, namely, the tailoring and damping technology on dynamic response of a thin-walled beam structure exposed to external time-dependent excitation.