• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.12
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• pp.15-22
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• 2011

Integrated-optic symmetric/asymmetric Mach-Zehnder interferometers at $1.3{\mu}m$ wavelength were studied as sensing part for electric-field measurement system. The devices were simulated based on the BPM software and fabricated utilizing Ti-diffused $LiNbO_3$ channel optical waveguides and lumped-type electrodes. A half-wave voltage of $V_{\pi}$=6.6V and modulation depth of 100% and 75% for a symmetric structure were measured for 200Hz and 1kHz electrical signal bandwidth, respectively. By the way, almost half-maximum power transmission was observed for asymmetric interferometers with ${\pi}$/2 intrinsic phase difference. Expected experimental measurements were observed for 1kHz electrical signal bandwidth.

• Current Applied Physics
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• v.18 no.12
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• pp.1473-1479
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• 2018

Recently multiferroic materials have attract great interest for the applications on memorial, spintronic and magneto-electric sensor devices for their spontaneous magneto-electric coupling properties. Research and development of the various kinds of multiferroics are indispensable factor for a new generation multifunctional materials. In this research, mechanical, electronic, magnetic and nonlinear optical properties of La modified $BiLaFe_2O_6$ (BLFO) and Mn modified $Bi_2FeMnO_6$ (BFMO) were studied as new members of multiferroic $BiFeO_3$ (BFO) series by first-principles calculations, and compared with the pure BFO to discover the optimized properties. Our results show that BLFO and BFMO have good mechanical stability as revealed by elastic constants that satisfy the stability criteria. All these compounds exhibit anisotropic and ductile nature. The enhanced properties by La and Mn substitution, such as increased hardness, improved magnetism, decreased band gap and comparable second harmonic generation responses reveal that the new multiferroic members of BLFO and BFMO would get wider application than their BFO counterpart. Our study is expected to providing an appropriate mechanical reference data as guidance for engineering of high efficiency multifunctional devices with the BFO series.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1756-1758
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• 1999

As new gas sensing material with high cata activity for NO decomposition and for CO oxid $LaFeO_3$ thin films with different thicknesses fabricated by the R.F. magnetron sputtering m on an $Al_2O_3$ substrates with Ag electrodes. The sensing characteristics of the $LaFeO_3$ thin films studied as a function of annealing temperature film thickness. The thin film annealed at showed the highest sensitivity of 110% for CO 60% for NO.

• Journal of Sensor Science and Technology
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• v.5 no.1
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• pp.37-42
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• 1996

ZnO films have been deposited on oxide grown Si wafers by the conventional thermal evaporation method. Anhydrous zinc acetate was directly heated and sublimed in the laboratory-made brass boat. The substrates temperature varied from $200^{\circ}C$ to $600^{\circ}C$. Oxygen has been flowed into the deposition chamber to change the partial pressure of oxygen. The films deposited at high oxygen pressure exhibited higher resistivity than films at low pressure. X-Ray Diffraction(XRD), Energy Dispersive Spectroscopy(EDS) and Rutherford Backscattering Spectrometry (RBS) were conducted on the films to reveal the crystallinity and composition of the ZnO films. The ZnO films deposited at high oxygen pressure were extremly sensitive to the humidity of higher than 70 % RH.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.245-247
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• 1987

In this thesis, ZnO semiconductor gas sensors doped by the $Al^{3+}$ were fabricated by the miexed oxide method. The specimens were sintered for 5(hr) at $1000-1200^{\circ}C$ and the I-V, sensitivity were investigated in acetone gas or ammonia gas. As a result, I-V curves of specimens as a function of temperature variation showed characteristics of linear resistor that the current was proportional to the, temperature at constant voltage. For the sensitivity of acetone, 1Wt $Al^{3+}$-ZnO has the hight 0.91, ammonia gas, 2Wt $Al^{3+}$-ZnO specimen has the hight 0.90. Hence, the operating temperature of specimens were both $300^{\circ}C$.

• Journal of the Korean institute of surface engineering
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• v.56 no.4
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• pp.219-226
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• 2023

Utilizing low-dimensional structures of oxide semiconductors is a promising approach to fabricate relevant gas sensors by means of potential enhancement in surface-to-volume ratios of their sensing materials. In this work, vertically aligned cupric oxide (CuO) nanorods are successfully synthesized on a transparent glass substrate via seed-mediated hydrothermal synthesis method with the use of a CuO nanoparticle seed layer, which is formed by thermally oxidizing a sputtered Cu metal film. Structural and optical characterization by x-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy reveals the successful preparation of the CuO nanorods array of the single monoclinic tenorite crystalline phase. From gas sensing measurements for the nitrogen monoxide (NO) gas, the vertically aligned CuO nanorod array is observed to have a highly responsive sensitivity to NO gas at relatively low concentrations and operating temperatures, especially showing a high maximum sensitivity to NO at 200 ℃ and a low NO detection limit of 2 ppm in dry air. These results along with a facile fabrication process demonstrate that the CuO nanorods synthesized on a transparent glass substrate are very promising for low-cost and high-performance NO gas sensors.

• Journal of the Mineralogical Society of Korea
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• v.12 no.1
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• pp.1-10
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• 1999

Talc (Mg3Si4O10(OH)2), one of the sheet silicate minerals, which is the hydrothermal alteration product of serpentinite at Cheongarm mine was prepared for the high pressure compressibility studies. Energy dispersive X-ray diffraction experiment was carried out using the Synchrotron Radiation with the Mao-Bell type diamond anvil cell at room temperature. Polycrystalline talc was mixed with MgO powder for pressure sensor as well as pressure medium in the sample chamber. High pressure runs were performed at pressures up to 35.2 GPa. Talc shows no phase transition within the present high pressure region. Bulk modulus of this talc was determined by the Birch-Murnaghan equation of state to be 78 GPa assuming its first pressure derivative Ko' of 4.

• Korean Journal of Materials Research
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• v.7 no.8
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• pp.640-645
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• 1997

Pd게이트 MOS센서의 수소검지특성에 Pd 박막의 증착조건이 미치는 영향에 대해서 조사였다. rf power의 증가와 증착온도의 증가는 모두 센서의 감도와 초기반응속도를 감소시켰으며 rf power의 변화보다는 증착온도의 변화에 의한 효과가 현저하였다. 절연막을 Si$_{x}$N$_{y}$ /SiO$_{2}$로 대신한 결과 SiO$_{2}$에서돠는 달리 시간이 지남에 따라 평탄대역전압이 여러 단계로 변화하는 양상을 보였다. rf power, 증착온도, 기판의 변화가 MOS 센서의 감도나 초기반응속도등의 센서특성에 영향을 미친다는 사실을 확인할 수 있었다.

• Journal of Sensor Science and Technology
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• v.7 no.1
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• pp.39-44
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• 1998

Low reflectance optical fiber mirrors in the continuous length of the single mode fiber were fabricated using mechanical splices and pieces of fiber coated with $TiO_{2}$ dielectric film at the cleaved end. When fiber mirrors of refelctance of about 1% were produced, the insertion loss ranged from 0.055dB to 0.3dB and the average insertion loss was 0.15 dB. These mirrors could be produced easy in the field.

• Journal of Sensor Science and Technology
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• v.15 no.1
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• pp.71-75
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• 2006

ITO (Indium Tin Oxide) thin films have been fabricated by rf magnetron sputtering with a target of a mixture $In_{2}O_{3]$(90 wt%) and $SnO_{2}$ (10 wt%). ITO films were sputtered with substrate temperature from 30 to $300^{\circ}C$ and working pressure from 1 to under 0.1 m Torr. ITO thin films surface morphology and electrical properties analyzed by SEM Photographs, and X-ray diffractions patterns. The resistivity of ITO thin films was $1.8{\times}10^{-5}{\Omega}/cm$.