• Journal of the Microelectronics and Packaging Society
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• v.8 no.2
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• pp.9-13
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• 2001

The effects of glass addition on the densification and the microwave properties of $(Ba_{0.5}Pb_{0.5})Nd_2Ti_5O_{14}$ dielectric system were studied. When 2~3 wt% of borosilicate glass were added, the density increased and the better microwave properties were obtained. When a sample was sintered at $950^{\circ}C$ with 3 wt% of glass, the quality factor and the temperature coefficient of the resonant frequency of the specimen were 4500 and +10 $ppm/^{\circ}C$, respectively. The dielectric constant, however, decreased from 90 to 75 with glass addition.

• Proceedings of the KAIS Fall Conference
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• 2008.05a
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• pp.184-185
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• 2008

본 연구에서는 ITO/PEDOT:PSS//PFO:MEH-PPV/LiF/Al 구조를 갖는 고분자 유기발광다이오드를 제작하여 발광 도펀트인 MEH-PPV의 농도에 따른 황색 PLED 소자의 전기 광학적 특성에 대하여 조사하였다. MEH-PPV의 농도를 각각 6, 7, 8, 9, 10 wt% 로 변화시켜 소자를 평가한 결과 9 wt%의 농도에서 가장 우수한 전기 및 광학적 특성을 보였으며, 16 V의 인가전압에서 약 630 cd/$m^2$의 휘도 특성과 256 mA/$cm^2$의 전류밀도 특성이 관찰되었다. 또한 10 wt%의 소자에서는 오히려 낮은 광학적 특성이 관찰되어 9 wt%에서 도펀트의 농도가 포화됨이 관찰되었고, 제작된 소자의 색좌표 (CIE coordiante)는 모든 소자에서 (x, y = 0,49, 0.49)로 거의 동일하게 나타났다.

• Journal of the Korean Ceramic Society
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• v.38 no.3
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• pp.280-286
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• 2001

10 이하의 저유전율을 갖는 (1-x)BaWO$_4$-xMg$_2$SiO$_4$(x=0.1~0.9) 세라믹스의 미세구조와 고주파 유전특성을 조사하였다. (1-x)BaWO$_4$-xMg$_2$SiO$_4$(x=0.1~0.9) 세라믹스는 정방정(tetragonal) 구조를 가진다. 0.1BaWO$_4$-0.9Mg$_2$SiO$_4$세라믹스는 BaWO$_4$와 $Mg_2$SiO$_4$의 상들이 공존하는 혼합상을 보였으며, $Mg_2$SiO$_4$가 이차사으로 형성된 것이 관찰되었다. 120$0^{\circ}C$~140$0^{\circ}C$에서 2시간 동안 소결된 (1-x)BaWO$_4$-xMg$_2$SiO$_4$(x=0.1~0.9) 세라믹스는 $\varepsilon$$_{r}$=6.37~8.21, Q.f=15000~99422 그리고 $ au$$_{f}$=73.9~48.9 ppm/$^{\circ}C$의 고주파 유전특성을 가졌다. $\tau$$_{f}$를 보정하기 위해, CaTiO$_3$(1,5 wt%)가 (1-x)BaWO$_4$-xMg$_2$SiO$_4$(x$\geq$0.9) 세라믹스에 첨가되었다. 135$0^{\circ}C$에서 2시간 동안 소결된 0.1BaWO$_4$-0.9Mg$_2$SiO$_4$+CaTiO$_3$(5 wt%) 세라믹스는 $\varepsilon$$_{r}$=7.3, Q.f=30532 그리고 $\tau$$_{f}$=-30 ppm/$^{\circ}C$의 고주파 유전특성을 얻었다. 얻었다.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.4
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• pp.366-372
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• 2019

In this paper, we fabricated a capacitive humidity sensor with an IDT(Interdigitated) electrode using commercial polyimide containing fluorine, and its properties were measured and analyzed. First, in order to analyze the composition of commercial polyimide, EDS analysis was performed after patterning process on a silicon wafer. The area of the humidity sensor was $1.56{\times}1.66mm^2$, and the width of the electrode and the gap between the electrodes were $3{\mu}m$ each. The number of electrodes was 166 and the length of the electrode was 1.294mm for the sensitivity of the sensor. The fabricated sensor showed that the sensitivity was 24 fF/%RH, linearity <${\pm}2.5%RH$ and hysteresis <${\pm}4%RH$. As a result of measuring the capacitance value according to the frequency change, the capacitance vlaue decreased with increasing frequency. Capacitance deviations with 10kHz and 100kHz were measured as 0.3pF on average.

• Journal of Sensor Science and Technology
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• v.8 no.3
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• pp.265-273
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• 1999

Various oxide films are commonly used as a sacrificial layer or etch mask in the fabrication of microelectromechanical systems (MEMS). Large residual strain of these oxide films causes the wafer to bow, which can have detrimental effects on photolithography and other ensuing processes. This paper investigates the residual strain of tetraethoxysilane (TEOS), low temperature oxide (LTO), 7 wt% and 10 wt% phosphosilicate glass (PSG). Euler beams and a bent-beam strain sensor are used to measure the residual strain. A poly silicon layer is used as the sacrificial layer, which is selectively etched away by $XeF_2$. First, the residual strain of as-deposited films is measured, which is quite large. The residual strain of the films is also measured after annealing them not only at $500^{\circ}C$, $600^{\circ}C$, $700^{\circ}$ and $800^{\circ}C$ in $N_2$ environment for 1 hour but also at the conditions for depositing a $2\;{\mu}m$ thick polysilicon at $585^{\circ}C$ and $625^{\circ}C$. Our results show that the 7 wt% PSG is best suited as the sacrificial layer for $2\;{\mu}$ thick polysilicon processes.

• Journal of the Mineralogical Society of Korea
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• v.14 no.2
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• pp.99-110
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• 2001

A gem-quality yttria-stabilized zirconium oxide crystals were synthesized by the skull-melting method, using the RF electrical apparatus. Principal raw materials used were $ZrO_2$and 25 wt.% $Y_2O_3$as stabilizer and 0.03~0.05 wt.% $Nd_2O_3$decolorizing agent were added to it. The single crystals were approximately 20$\times$63 mm in size with chemical composition $Zr_{0.73}$ $Y_{0.27}$ $O_{1.87}$ . The crystals are isotropic with no appreciable anisotropism under a polarizing microscope. Their refractive indices are in the range of 2.15~2.18, specific gravity 5.85, Mohs' hardness 8~8.5, and reflectivity 13.47%. The zirconia crystals were confirmed to have cubic structure with Face-centered lattice(Z=4), space group Fm3m ($CaF_2$-type structure) and unit cell parameters are a=5.157 $\AA$. The optimal growing conditions for yttria-stabilized zirconia are 50 kW, 2.94 MHz in power and to use a crucible with 105 mm $\times$ 135 mm in size. When the lowering speed of the crucible was set 16mm/hr gave the best yield, 42%. Since the refractive index(2.15~2.18) of cubic zirconia is smaller than that of diamond, the angle between crown and pavilion should be fashioned to make it smaller than $40.5^{\circ}$ to show the maximum brilliancy and fire.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.3 s.47
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• pp.369-375
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• 2004

In this study, liquid crystalline (LC) is formed using Gemini surfactant (GS) type and moisturizing effect in vivo is measured. $3.0\;wt\%$ of sodium dicocoyl ethylene diamine (PEG)-15 sulfate (SCD-PEG-15S) is used as GS and $4.0\;wt\%$ of hydrogenated dimer acid esters (HDAE) as booster. For stabilizers, $2.0\;wt\%$ of behenyl alcohol (BA) and $1.0\;wt\%$ of Iyso-lecithin (LyL) are utilized. It is stabilized in pH from 4.0 to 10.5 and the best condition is in pH 6.5. The value of viscosity is $8,000\pm500$ cP. The most excellent particles are formed within the range of 4.0 to 15.5 um. Formed LC is observed around LC particles using polarization microscope. It is also observed that lamellar gel network structure is formed around LC particles. Moisturizing effect is improved by $13.6\%$ (P<0.05) compared to control when measured 30 min later after coating samples. After 1 h, moisturizing effect is improved by 1$12.6\%$ (P<0.05) than control while showing $28.3\%$ (P<0.05) of improvement after 4 h. These results may be caused from that manufactured LC forms lamellar structure so that it has better water-holding ability and absorbance of oil increases. This formula could be utilized by delivery system (DS) on skin so that this technology can be applied for manufactuing pharmaceuticals and cosmetics.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.26 no.1
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• pp.1-8
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• 2020

Background: The aim of this study was to conduct an Otago exercise program with total knee replacement patient (TKR) in a clinical setting and ascertain its effects on balance, walking ability and falls efficacy. Methods: The participating subjects were 30 people who had been diagnosed with TKR. They were assigned to two groups (Exp; Otago exercise and general physical therapy, n=15; Con; balance exercise and general physical therapy, n=15), and the exercises were conducted for three sessions per week for four weeks. The main balance outcomes were evaluated using the timed up and go test (TUG), while walking ability was evaluated using the 10m walk test (10MWT), direction change ability was measured using the figure 8 of walk test (F8WT), and the decrease of fear was evaluated using the modified falls efficacy scale (MFES). Results: In the analysis results, the Exp group showed significant increases in TUG, 10MWT, and F8WT within the both groups. There were significant differences in all variables between the Exp group and the Con group at the post-intervention evaluation, but there was no significant difference between the groups with respect to the TUG. Conclusion: The results of this study demonstrated that Otago exercise would be useful to improve balance and walking for TKR patients who want to improve their abilities and activities of daily living.

• Polymer(Korea)
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• v.37 no.1
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• pp.86-93
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• 2013

In this work, the thermal, antibiotic properties and far-infrared emissivity of fluorinated illite embedded polypropylene non-woven fibers (f-illite/PP fibers) were investigated in the presence of 0, 1, 3, 5 and 7 wt% illite powders. The thermal properties of f-illite/PP fibers were studied by thermogravimetric analysis (TGA). Their antibiotic properties were examined by Staphylococcus aureus and Klebsiella pneumoniae test. Their far-infrared emissivity was also investigated by Fourier transform infrared spectroscopy. From the experimental results, thermal, antibiotic properties and far-infrared emissivity of f-illite/PP fibers were improved by increasing fluorinated illite contents and the property values of 5 wt% f-illite/PP fibers were increased remarkably by about 10.3, 41.2 and 9.8% respectively in comparison with PP non-woven fibers having no fluorinated illite additive. This result was interpreted as the development of interfacial adhesion force between the polymer chains due to the fluorination of illite power.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.39-41
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• 2000

Carbon is an attractive candidate for use in eletrochemical supercapacitors that depend on charge storage in the electrode/eletorlyte international double layer. Property of an electrical double layer capacitor depend both on the technique used to prepare the electrode and on the current collector structure. The study is to research that $V_2O_5$-carbon (SP270) composite electrode for supercapacitor. The discharge capacitance of $V_2O_5$-SP270 (20wt%) in 1st and 35cyc1e was 14F/g and 8.5F/g at current density of $0.1mA/cm^2$. The discharge process of $V_2O_5$-SP270 (20wt%) composite electrode is larger than that others.