• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1205-1208
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• 1995

The optically-gated p-i-n diode switches have been fabricated with gold-compensated silicon. The turn-on and turn-off delay times and the rise and fall times were measured as a function of optical power level, bias, and pulse width. The turn-on characteristics shows a strong dependence an optical pulse power and a delay time(${\delta}{\iota}$) between two pulses, but a weak dependence on the width of optical pulse. Actually there is no turn-off delay in gold-doped p-i-n switches and the fall time is negligible.

• Journal of Magnetics
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• v.11 no.4
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• pp.156-159
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• 2006

We have studied the magnetic properties of the CuNi nanoparticles for three different sizes prepared by plasma and chemical techniques. The magnetization is enormously enhanced with decreasing the nanoparticle size. This enhanced magnetic moment shows almost inversely linear temperature dependence, which could be interpreted by the Langevin-type superparamagnetism. The field dependence exhibits ferromagnetic-like behavior with weak hysteresis, which could described in terms of uncompensated spin and/or surface anisotropy. In addition, the magnetic data suggest that the CuNi nanoparticles produced by the plasma method result in significantly less oxidized metallic nanoparticles than those prepared by other techniques.

• Korean Journal of Crystallography
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• v.12 no.3
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• pp.157-161
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• 2001

The observe relaxation phenomena and freezing behavior in Pb(Mg/sub ⅓/Nb/sub ⅔/O₃, relaxor ferroelectrics, weak electric-field properties as well as strong electric-field properties were investigated. The temperature dependence of the dielectric properties obtained using the low electric-field of 1 V/w was investigated. The dielectric properties obtained from the slope of the dielectric hysteresis loop and the temperature dependence of the pyroelectric properties were also investigated. When fitting all the experimental data with the Vogel-Filcher relation, a close agreement between the experimental data and equation was observed. The freezing temperature could be consistently calculated by the various methods.

• Progress in Superconductivity
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• v.3 no.2
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• pp.146-150
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• 2002

We performed the point contact spectroscopy on newly discovered superconductor $MgB_2$ thin films with Au tip. In the point contact spectroscopy of the metallic Sharvin limit, the differential conductance below the gap is twice as that above the gap by virtue of Andreev Reflection. After some surface cleaning processes of sample preparation such as ion-milling and wet etching, the obtained dI/dV versus voltage curves are relatively well fitted to the Blonder-Tinkham-Klapwijk (BTK) formalism. Gaps determined by this technique were distributed in the range of 3meV~ 8meV with the BCS value of 5.9meV in the weak coupling limit. We attribute these discrepancies to the symmetry of the gap parameter and the degradation of the surface of the sample. We also present the temperature dependence of the conductance vs voltage curve and thereby the temperature dependence of the gap.

• Progress in Superconductivity
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• v.13 no.1
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• pp.47-51
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• 2011

Mono-atomic-layer graphene is an interesting system for studying the relativistic carrier transport arising from a linear energy-momentum dispersion relation. An easy control of the carrier density in graphene by applying an external gate field makes the system even more useful. In this study, we measured the Josephson current in a device consisting of mono-layer graphene sheet sandwiched between two closely spaced (~300 nm) aluminum superconducting electrodes. Gate dependence of the supercurrent in graphene Josephson junction follows the gate dependence of the normal-state conductance. The gate-tunable and relatively large supercurrent in a graphene Josephson junction would facilitate our understanding on the weak-link behavior in a superconducting-normal metal-superconducting (SNS) type Josephson junction.

• Progress in Superconductivity
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• v.9 no.2
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• pp.136-139
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• 2008

InAs semiconductor nanowires can provide a promising platform to integrate superconducting quantum circuit, which exploits tunable supercurrent under the operation of gate voltage. We report temperature and magnetic field dependence of the nanowire superconducting junctions, which is in agreement with the proximity-effect theory of superconductor-normal metal-superconductor weak link. Superconducting coherence length of the InAs nanowire is estimated from the fit and magnetic-field dependence of the critical current and the subgap structure of dI/dV is discussed as well.

• International Journal of High-Rise Buildings
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• v.8 no.4
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• pp.313-324
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• 2019

This paper presents the analysis of wind speeds data measured on top of three neighboring high-rise buildings close to a beach in Xiamen city, China, during Typhoon "Usagi" 2013. Wind tunnel simulation was carried out to validate the field measurement results. Turbulence intensity, turbulence integral scale, power spectrum and cross correlation of recorded wind speed were studied in details. The low frequency trend component of the typhoon speed was also discussed. The field measurement results show turbulence intensity has strong dependence to the wind speed, upwind terrain and even the relative location to the Typhoon center. The low frequency fluctuation could severely affect the characteristics of wind. Cross correlation of the measured wind speeds on different buildings also showed some dependence on the upwind terrain roughness. After typhoon made landfall, the spatial correlation of wind speeds became weak with the coherence attenuating quickly in frequency domain.

• Journal of applied mathematics & informatics
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• v.13 no.1_2
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• pp.247-259
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• 2003

Optimal control problem for the exploitaton of oil is investigated. The optimal control problem under consideration in this paper is governed by weak coupled parabolic PDEs and involves with pointwise state and control constraints. The properties of solution of the state equations and the continuous dependence of state functions on control functions are investigated in a suitable function space; existence of optimal solution of the optimal control problem is also proved.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.5
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• pp.376-382
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• 2001

Magnetic and transport properties in the ceramic specimen of L $a_{0.7}$S $r_{0.3}$Fe $O_3$ with orthohombic structure has been investigated. Weak ferromagnetism has been observed in a ceramic sample of L $a_{0.7}$S $r_{0.3}$Fe $O_3$. Large dielectric relaxation of Debye type is observed in paramagnetic states within the temperature range of 130K~200K. From the temperature dependence of the characteristic frequency, we concluded that the elementary process of the dispersion is related to holes hopping between F $e^{3+}$ and F $e^{4+}$ ions. The temperature dependencies of thermoelectric power and Dc conductivity suggest that the charge carrier responsible for the conduction are strongly localized. These experimental results have been interpreted in terms of a hopping process involving small polaron.n.laron.n.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.2C
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• pp.150-159
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• 2007

In Part 1 of this paper, the test statistics are obtained for detecting weak known signals in observations corrupted by multiplicative and first-order Markov additive noise. In this second part, the asymptotic and finite sample-size performance of several detectors are obtained and compared based on the test statistics. From the performance comparisons, it is confirmed that the dependence among interference components need to be taken into account to maintain the detection performance.