• The Journal of Korean Academy of Prosthodontics
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• v.42 no.3
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• pp.301-306
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• 2004

Statement of problem. Fibronectin mediates its biological effects by binding to integrins on cell membranes through a consensus site including the Arg-Gly-Asp (RGD) sequence within tenth type III module. Purpose. The purpose of our study was to investigate the adsorption affinity of human recombinant fibronectin peptide (hFNIII 9-10) to titanium and to investigate the effect of the surrounding ionic composition on the adsorption process. Material and methods. As for evaluating the affinity of hFNIII 9-10 to Ti, titanium disks were incubated in 40, 80 and $120{\mu}g/ml$ hFNIII 9-10 solution at $37^{\circ}C$ overnight, repectively. As for evaluating the effect of surrounding ionic concentration, hFNIII 9-10 was dissolved in distilled water, phosphate buffered saline and RPMI 1640. Optical density (O.D.) was measured in ELISA reader. Results. The results were as follows; 1. The adsorption of hFNIII 9-10 showed significantly highest mean optical density (O.D.) value in $80{\mu}g/ml$. 2. The difference of ionic composition in DW, PBS and RPMI did not influence the adsorption amount of hFNIII 9-10.

• Korean Journal of Materials Research
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• v.11 no.1
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• pp.27-33
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• 2001

The growth characteristics of 4-fold grain which was appeared in KLN deposition on $Pt/Ti/SiO_2/Si(100)$ substrate was studied by varying process variables. Substrate temperature, sputtering pressure, rf power were selected as process variables, and experiment was carried out near optimum fabrication condition. When using K and Li enriched target, the optimum fabrication conditions were substrate temperature of $600^{\circ}C$, sputtering pressure of 150mTorr, rf power of 100 W and its surface morphology is sensitively varied by small deposition condition changes. KLN is composed of elements which have large difference of boiling point. And it is difficult to fabricate thin film at high temperature and high vacuum deposition condition. Furthermore the phenomenon during deposition process can not be explained by using Thorton's model which explains the relation between thin film structure and melting point of thin film materials. These phenomenon can be explained using boiling point of elements which consist of thin film material.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.4
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• pp.362-368
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• 2023

Multilayered actuators using Pb(Mg_1/3Nb_2/3)O₃-Pb(In_1/2Nb_1/2)O₃-PbTiO₃ (PMN-PIN-PT) crystals have demonstrated excellent properties, but are costly and lack mechanical strength. Textured PMN-PIN-PT ceramics exhibit robust mechanical strength and comparable properties to their single crystals form. However, the development of multilayered actuators using textured PMN-PIN-PT ceramics has not been achieved until now. This study presents the development of a multilayered actuator using textured 0.37PMN-0.29PIN-0.34PT ceramics with an Ag_0.9/Pd_0.1 inner electrode, co-fired at 950℃. A random 0.37PMN-0.29PIN-0.34PT ceramics multilayered actuator was also developed for comparison. The multilayered actuator consisted of 9 ceramic layers (36 ㎛ thickness) with an overall actuator thickness of 0.401 mm. The textured and random 0.37PMN-0.29PIN-0.34PT ceramics-based multilayered actuators achieved displacements of 0.61 ㎛ (0.15% strain) and 0.23 ㎛ (0.057% strain) at a low applied peak voltage of 100 V. These results suggest that the developed multilayered actuator using high-performance textured 0.37PMN-0.29PIN-0.34PT ceramics has the potential to replace expensive single crystal-based actuators cost-effectively.

• Journal of Conservation Science
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• v.27 no.1
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• pp.61-74
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• 2011

The material characteristics of Chos$\breve{o}$n whiteware were investigated by analyzing and comparing the body and glaze compositions of whiteware shards excavated at the Kwangju royal kilns, Ch'unghyodong, and four other local-level kilns. In Korea, the rise of whiteware technology began in the early years of the Chos$\breve{o}$n dynasty, when the indigenous tradition of Kory$\breve{o}$ celadon was strongly influenced by the whiteware aesthetics of the Chinese Ming dynasty. The Kwangju royal kilns eventually made hard-textured whiteware of a quality equivalent to that of the Chinese by using type of porcelain stone that contained slightly less $Fe_2O_3$ and $TiO_2$ and slightly more $K_2O$ than that used for celadon. In contrast, the potters of Ch'unghyodong achieved the same level of quality by finding and using a totally different material: kaolinitic clay. The porcelain stone used at the Kwangju kiln was commonly found in Korea and south China, whereas kaolinitic clay (which has a high aluminum content) was typically found in north China, and was only rarely used in Korea. The flux component of the glaze compositions was mostly limestone, first in burnt form and later in crushed form, and the clay component was often glaze stone, which was a finer-grained porcelain stone with a higher proportion of feldspar. In the future, this comparative analytical study of Korean whiteware components should be extended to the $18^{th}$- and $19^{th}$-century kilns that are currently being excavated at a rapid pace.

• Journal of the Korean Ceramic Society
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• v.39 no.9
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• pp.822-828
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• 2002

Fabrication and electrical characterization of R. F. High-power unit capacitors were investigated to study on condition of fabrication processing for R. F. High-power unit capacitor and electrical characteristics according to addition of $ZrO_2$. The unit capacitors were fabricated using tape casting. The optimum mixture ratio of dielectrics and mixing binder for the slurry fabrication was 57.5∼60.0: 42.5∼40.0 wt%. The slurry viscosity was 4000∼5000 cps and casting state of green tape fabricated using these slurry was excellent. Optimum stacking was made by 200 kg/$cm^2$ pressure with 80$^{\circ}C$ heating. $ZrO_2$ was added to improve the electrical characteristics of unit capacitor, especially breakdown characteristics. The dielectric constant and loss factor of the unit condenser having different $ZrO_2$ amounts was not changed in the addition range of 1 to 5 wt%. Also, dielectric constant was not changed in the frequency range of 10 to 500 kHz. It was found that characteristics of resistance voltage was improved through the formation of $CaZrO_3$ and the reduction of particle size as about 3wt% $ZrO_2$ was added.

• Korean Journal of Materials Research
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• v.30 no.7
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• pp.343-349
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• 2020

NKN [(Na,K)NbO₃] is a candidate lead-free piezoelectric material to replace PZT [Pb(Zr,Ti)O₃]. A single crystal has excellent piezoelectric-properties and its properties are dependent of the crystal orientation direction. However, it is hard to fabricate a single crystal with stoichiometrically stable composition due to volatilization of sodium during the growth process. To solve this problem, a solid solution composition is designed (Na,K)NbO₃-Ba(Cu,Nb)O₃ and solid state grain growth is studied for a sizable single crystal. Ceramic powders of (Na,K)NbO₃-M(Cu,Nb)O₃ (M = Ca, Sr, Ba) are synthesized and grain growth behavior is investigated for different temperatures and times. Average normal grain sizes of individual specimens, which are heat-treated at 1,125 ℃ for 10 h, are 6.9, 2.8, and 1.6 ㎛ for M = Ca, Sr, and Ba, respectively. Depending on M, the distortion of NKN structure can be altered. XRD results show that (NKN-CaCuN: shrunken orthorhombic; NKN-SrCuN: orthorhombic; NKN-BaCuN: cubic). For the sample heat-treated at 1,125 ℃ for 10 h, the maximum grain sizes of individual specimens are measured as 40, 5, and 4,000 ㎛ for M = Ca, Sr, and Ba, respectively. This abnormal grain size is related to the partial melting temperature (NKN-CaCuN: 960 ℃; NKN-SrCuN: 971 ℃; NKN-BaCuN: 945 ℃).

• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1197-1205
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• 2018

UV protection cosmetics belong to functional cosmetics and contain organic or inorganic UV blocking pigments. The inorganic UV blocking pigments are mainly zinc oxide and titanium dioxide. It is known that inorganic UV blocking pigment has a diameter of 60 to 100 nm and has good blocking ability of UVA and UVB. Also, it has high inactivity against sunlight including UV and is excellent in safety. In addition, it is not absorbed or accumulated on the skin like organic pigments and does not cause skin irritation or allergy. In this study, mica, a plate-shaped inorganic pigment, nanosized titanium dioxide, an UV blocking material, and hydrophobic silica were surface-treated with surfactants. And then, titanium dioxide nanoparticles and silica were physically adsorbed on the mica by non-chemical mutual attraction due to differences in charge. Thereafter, the mica complex was surface-treated with silane to prepare a hydrophobic UV blocking pigment complex. The plate-shaped UV blocking composite improves the cohesiveness of a general nanoparticle material titanium dioxide, enhances UV blocking effect due to uniform dispersion, and can greatly improve dispersion stability in cosmetic formulations by surface treatment with hydrophobic property. The surface charge of the pigment was evaluated by zeta potential. The properties of the UV blocking pigment complex were evaluated by FE-SEM, XRD, FT-IR and UV-VIS.

• Transactions on Electrical and Electronic Materials
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• v.12 no.5
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• pp.222-225
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• 2011

Lead zirconate titanate (PZT) films were fabricated on Pt/Ti/$SiO_2$/Si substrate by the sol-gel method using a sol containing poly(N-vinylpyrrolidone) (PVP). PVP in alkoxide solutions can suppress the condensation reaction in gel films during heat treatment, and increase the viscosity of alkoxide solutions. Single-phase PZT films as thick as 1 ${\mu}m$ were deposited by repetitive coating with successive third-step heat treatments at 150$^{\circ}C$, 350$^{\circ}C$ and 650$^{\circ}C$. After heat treatment, the films were crack free, and optically transparent. As a result, we demonstrated a PZT film with a PVP molar ratio of 0.5, which has a permittivity of 734, a dielectric loss of 0.042, a $P_r$ of 40.5 ${\mu}C/cm^2$ and an $E_c$ of 156 kV/cm.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.9
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• pp.541-545
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• 2017

$Pb(Zr_{0.52}Ti_{0.48})O_3$ (PZT) films with a thickness of $5{\sim}10{\mu}m$ at the morphotropic phase boundary were fabricated by aerosol-deposition (AD), and their phase evolution and electrical properties were investigated. The microstructure of the AD PZT films revealed nanosized grains with a low crystallinity and a dense structure at room temperature. The AD PZT films showed a mixture of tetragonal and rhombohedral phases. The post-annealing temperature was varied to study the phase transition behavior. The crystallinity of the AD PZT films was enhanced by annealing at 450, 550, and $650^{\circ}C$ for 2 h. At $650^{\circ}C$, the tetragonal and rhombohedral phases reacted to form a bridge phase between the two phases. The polarization-electric field hysteresis loops of the AD PZT film annealed at $650^{\circ}C$ exhibited a smaller cohesive field and a lower slim hysteresis than the films annealed at 450 and $550^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.49 no.5
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• pp.475-483
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• 2012

High capacitance X5R MLCCs based on $BaTiO_3$ ceramic dielectric layers exhibit a single broad, asymmetric arc shape impedance and modulus response over the wide frequency range between 1 MHz to 0.01 Hz. Analysis according to the conventional brick-layer model for polycrystalline conductors employing a series connection of multiple RC parallel circuits leads to parameters associated with large errors and of little physical significance. A new parametric impedance model is shown to satisfactorily describe the experimental spectra, which is a parallel network of one resistor R representing the DC conductivity thermally activated by 1.32 eV, one ideal capacitor C exactly representing bulk capacitance, and a constant phase element (CPE) Q with complex capacitance $A(i{\omega})^{{\alpha}-1}$ with ${\alpha}$ close to 2/3 and A thermally activated by 0.45 eV or ca. 1/3 of activation energy of DC conductivity. The feature strongly indicate the CK1 model by J. R. Macdonald, where the CPE with 2/3 power-law exponent represents the polarization effects originating from mobile charge carriers. The CPE term is suggested to be directly related to the trapping of the electronic charge carriers and indirectly related to the ionic defects responsible for the insulation resistance degradation.