• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.6
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• pp.518-524
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• 2001

We report the current limiting properties of superconducting fault current limiters (SFCL). Our SFCL was patterned in a spiral type on a YB $a_2$C $u_3$$O_{7-x}$(YBCO) film deposited using rf sputtering techniques and was coated with a gold shunt layer in order to disperse the heat generated at hot spots in the YBCO film. Current increased up to 13.5 $A_{peak}$ at 60 Hz for the voltage of 13 $V_{peak}$, which is the minimum quench point, and increased up to 17.6 $A_{peak}$ at 60 Hz fo the voltage fo 141.4 $V_{peak}$. The quench completion time was 5 msec at 13 $V_{peak}$ and 4 msec at 141. $V_{peak}$ respectively. we think that this architecture using spiral-type SFCL can be useful for the protection of the power delivery systems from fault currents.s. currents.s.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.197-197
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• 2016

Commercially pure titanium (CP Ti) and Ti-6Al-4V alloys have been widely used for biomedical applications. However, the use of the Ti-6Al-4V alloy in biomaterial is then a subject of controversy because aluminum ions and vanadium oxide have potential detrimental influence on the human body due to vanadium and aluminum. Hence, recent works showed that the synthesis of new Ti-based alloys for implant application involves more biocompatible metallic alloying element, such as, Nb, Hf, Zr and Mo. In particular, Nb and Hf are one of the most effective Ti ${\beta}-stabilizer$ and reducing the elastic modulus. Plasma electrolyte oxidation (PEO) is known as excellent method in the biocompatibility of biomaterial due to quickly coating time and controlled coating condition. The anodized oxide layer and diameter modulation of Ti alloys can be obtained function of improvement of cell adhesion. Manganese(Mn) plays very important roles in essential for normal growth and metabolism of skeletal tissue in vertebrates and can be detected as minor constituents in teeth and bone. Radio frequency(RF) magnetron sputtering in the various PVD methods has high deposition rates, high-purity films, extremely high adhesion of films, and excellent uniform layers for depositing a wide range of materials, including metals, alloys and ceramics like a hydroxyapatite. The aim of this study is to research the Mn coatings on the micro-pore formed Ti-29Nb-xHf alloys by RF-magnetron sputtering for dental applications. Ti-29Nb-xHf (x= 0, 3, 7 and 15wt%, mass fraction) alloys were prepared Ti-29Nb-xHf alloys of containing Hf up from 0 wt% to 15 wt% were melted by using a vacuum furnace. Ti-29Nb-xHf alloys were homogenized for 2 hr at $1050^{\circ}C$. Each alloy was anodized in solution containing typically 0.15 M calcium acetate monohydrate + 0.02 M calcium glycerophosphate at room temperature. A direct current power source was used for the process of anodization. Anodized alloys was prepared using 270V~300V anodization voltage at room. Mn coatings was produced by RF-magnetron sputtering system. RF power of 100W was applied to the target for 1h at room temperature. The microstructure, phase and composition of Mn coated oxide surface of Ti-29Nb-xHf alloys were examined by FE-SEM, EDS, and XRD.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2000.11a
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• pp.711-727
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• 2000

In this paper, the design of the successive detection logarithmic amplifier(SDLA) is reviewed for radar and EW system, and implemented in hybrid MIC. The SDLA operates over the 5 to 7㎓ frequency range. the unit has a dynamic range of -80㏈m to 0㏈m, a logging accuracy of ±1.4㏈, a legging slope 19.2㎷/㏈, and a gain flatness of ± 1.2㏈. Input VSWR of less than 2, noise figure of 2㏈, video impedance of 900Ω and output voltage range of 0 to 1.53V DC have been obtained over 80㏈ of dynamic range.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.1013-1019
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• 2007

Amorphous silicon and silicon-nitride films were deposited using plasma-enhanced chemical vapor deposition (PECVD) method at $150^{\circ}C$. As fraction of $H_2$ in source gas was increased, characteristics of low-temperature silicon-nitride films approached those of conventional high-temperature films; the refractive index approached 1.9 and the ratio of nitrogen-hydrogen bonds to silicon-hydrogen bonds increased. And also, as fraction of $H_2$ in source gas was increased, characteristics of low-temperature silicon films approached those of conventional high-temperature films; refractive index and optical band gap approached 4.2 and 1.8 eV, and $[Si-H]/([Si-H]+[Si-H_2])$ increased. Lower RF power and process-pressure made the amorphous silicon films to be better properties. Increase of $H_2$ ratio seemed as the common factor to get reliable amorphous silicon and silicon-nitride films for thin-film-transistors (TFTs) at low temperature.

• Journal of IKEEE
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• v.26 no.2
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• pp.232-239
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• 2022

We analyzed the effect of post-annealing on lithium phosphate (Li₃PO₄) solid-state thin-film. Li₃PO₄ thin films were deposited by radio frequency (RF) sputtering, with subsequent annealing of the films at 200-400 ℃. SEM imaging of the sample surfaces showed no significant difference in morphology between the annealed and non-annealed samples. XRD analysis indicated that the samples consist of an amorphous-like structure. Post-annealing changes in binding energy were confirmed by XPS analysis, while the leakage current density at -6 V was measured to be about 7.15 times lower in a device that had been annealed at 400 ℃ vs a non-annealed device. It was confirmed that the leakage current decreased with increasing post-annealing temperature.

• Korean Journal of Materials Research
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• v.12 no.12
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• pp.962-966
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• 2002

The $SrBi_2$$Nb_2$$O_{9}$ (SBN) thin films were deposited with $SrNb_2$$O_{6}$ / (SNO) and $Bi_2$$O_3$ targets by co-sputtering method. For the growth of SBN thin films, we adopted the various power ratios of two targets; the power ratios of the SNO target to $Bi_2$$O_3$ target were 100 W : 20 W, 100 W : 25 W, and 100 W : 30 W during sputtering the SBN films. We found that the electrical properties of SBN films were greatly dependent on Bi content in films. The $Bi_2$Pt and $Bi_2$$O_3$ phase as second phases occurred at the films with excess Bi content greater than 2.4, resulting in poor ferroelectric properties. The best growth condition of the SBN films was obtained at the power ratio of 100 W : 25 W for the two targets. At this condition, the crystallinity and electrical properties of the films were improved at even low annealing temperature as $700^{\circ}C$ for 1h in oxygen ambient and the Sr, Bi and Nb component in the SBN films were about 0.9, 2.4, and 1.8 respectively. From the P-E and I-V curves for the specimen, the remnant polarization value ($2P_{r}$) of the SBN films was obtained about 6 $\mu$C/c $m^2$ at 250 kV/cm and the leakage current density of this thin film was $2.45$\times$10^{-7}$ $A/cm^2$ at an applied voltage of 3 V.V.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.589-592
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• 2002

The $Sr_{0.7}Bi_{2.3}Ta_2O_9$(SBT) thin films are deposited on Pt-coated electrode(Pt/TiO2/SiO2/Si) using RF magnetron sputtering method. The structural and electric properties of SBT capacitors were influenced with annealing atmosphere. In the XRD pattern, the SBT thin films in all annealing atmosphere had (105) orientation. In the SEM images, Bi-layered perovskite phase was crystallized in all annealing atmosphere and grains largely grew in oxygen annealing atmosphere. The maximum remanent polarization and the coercive electric field in oxygen annealing atmosphere are $12.40{\mu}C/cm^2$ and 48kV/cm respectively. The dielectric constant and leakage current density annealing in oxygen atmosphere are 340 and $6.81{\times}10^{-10}A/cm^2$ respectively. The fatigue characteristics of SBT capacitors did not change up to $10^{10}$ switching cycles.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.4
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• pp.305-310
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• 2008

Deep trench etching of silicon was investigated as a function of RF source power, DC bias voltage, $C_4F_8$ gas flow rate, and $O_2$ gas addition. On increasing the RF source power from 300 W to 700 W, the etch rate was increased from $3.52{\mu}m/min$ to $7.07{\mu}m/min$. The addition of $O_2$ gas improved the etch rate and the selectivity. The highest etch rate is achieved at the $O_2$ gas addition of 12 %, The selectivity to PR was 65.75 with $O_2$ gas addition of 24 %. At DC bias voltage of -40 V and $C_4F_8$ gas flow rate of 30 seem, We were able to achieve etch rate as high as $5.25{\mu}m/min$ with good etch profile.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.11
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• pp.603-608
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• 2000

$(Ba, Sr)TiO_{3}$[BST] thin films were fabricated on the Pt/TiO$_2$/SiO$_2$/Si substrate by the RF sputtering. The structure and dielectric properties of the BST thin films with the substrate temperature were investigated. Increasing the substrate temperature, The BST phase increased and barium multi titanate phases decreased. Increasing the frequency, the dielectric constant decreased and the dielectric loss increased. The dielectric constant and dielectric loss of the BST thin films deposited at 50$0^{\circ}C$ were 300 and 0.018, respectively at 1 kHz. The leakage current density of the BST thin films deposited at 50$0^{\circ}C$ was $10^{-9}$ A/$\textrm{cm}^2$ with applied voltage of 3V. Because of the high dielectric constant(300), low dielectric loss(0.018) and low leakage current($10^{-9}$ A/$\textrm{cm}^2$), BST thin films deposited at 50$0^{\circ}C$ is expecting for the application of DRAM.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.76-76
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• 2000

최근 비정질 SiC 박막은 열과 광안정도면에서 비정질 Si 박막에 비해 우수하며 공정변수들을조절함으로써 비교적 쉽고 다양하게 광학적.전기적 특성을 얻을 수 있고, 낮은 광흡수계수 및 105($\Omega$cm)1 이상의 높은 전도도를 가지고 있어 Plasma Enhanced Chemical Vapor Deposition(PECVD)을 통해 가전자제어 (Valency electron control)가 가능한 비정질 SiC 박막이 제작된 이래 대한 많은 연구가 진행되고 있다. 결정성이 없는 비정질 물질은 상대적으로 낮은 온도에서 성장이 가능하며, 특히 glow-sidcharge 방식으로 저온에서 성장시킬 수 있음에 따라 유리등과 같은 다른 저렴한 물질을 기판으로 이용, 넓은 면적의 비정질 SiC 박막을 성장시켜 여러 분야의 소자에 응용되고 있다. 비정질 SiC 박막이 넓은 에너지띠 간격을 갖는 물질이라는 점과 화학적 안정성 및 높은 경도, 비정질성에 기인한 대면적 성장의 용이성 등의 장점이외에, 원자의 성분비 변화에 의해 에너지띠 간격(1.7~3.1eV)을 조절할 수 있다는 점은 광전소자의 응용에 큰 잠재성이 있음을 나타낸다. PECVD 방식으로 성장된 비정질 SiC 박막은 태양전지의 Window층이나 발광다이오드, 광센서, 광트랜지스터 등에 응용되어 오고 있다. 본 연구에서는, RF-PECVD(ULVAC CPD-6018) 방법에 의하여 비정질 Si1-xCx 박막을 2.73Torr의 고정된 압력에서 RF 전력(50~300W), 증착온도(150~30$0^{\circ}C$), 주입 가스량 (SiH4:CH4)등의 조건을 다양하게 변화시켜가며 증착된 막의 특성을 평가하였다. 성장된 박막을 X-ray Photoelectron Spectroscopy(XPS), UV-VIS spectrophotometer, Ellipsometry, Atomic Force Microscopy(AFM)등을 이용하여 광학적 밴드갭, 광흡수 계수, Tauc Plot, 그리고 파장대별 빛의 투과도의 변화를 분석하였으며 각 변수가 변화함에 따라 광학적 밴드갭의 변화를 정량적으로 조사함으로써 분자결합상태와 밴드갭과 광 흡수 계수간의상관관계를 규명하였고, 각 변수에 따른 표면의 조도를 확인하였다. 비정질 Si1-xCx 박막을 증착하여 특성을 분석한 결과 성장된 박막의 성장률은 Carbonfid의 증가에 따라 다른 성장특성을 보였고, Silcne(SiH4) 가스량의 감소와 함께 박막의 성장률이 둔화됨을 볼 수 있다. 또한 Silane 가스량이 적어지는 영역에서는 가스량의 감소에 의해 성장속도가 둔화됨을 볼 수 있다. 또한 Silane 가스량이 적어지는 영역에서는 가스량의 감소에 의해 성장속도가 줄어들어 성장률이 Silane가스량에 의해 지배됨을 볼 수 있다. UV-VIS spectrophotometer에 의한 비정질 SiC 박막의 투과도와 파장과의 관계에 있어 유리를 기판으로 사용했으므로 유리의투과도를 감안했으며, 유리에 대한 상대적인 비율 관계로 투과도를 나타냈었다. 또한 비저질 SiC 박막의 흡수계수는 Ellipsometry에 의해 측정된 Δ과 Ψ값을 이용하여 시뮬레이션한 결과로 비정질 SiC 박막의 두께를 이용하여 구하였다. 또한 Tauc Plot을 통해 박막의 optical band gap을 2.6~3.7eV로 조절할 수 있었다.