Gyu-Bo Kim

Variation of pinning mechanism in Bi1.6Pb0.4Sr2CaCu2O8+δ single crystal

Abstract The pinning mechanism of Bi 1.6 Pb 0.4 Sr 2 CaCu 2 O 8+ δ single crystal was investigated by analyzing the normalized pinning forces. We found that our single crystal showed a very strong secondary peak effect in a wide temperature range, from 20 to 80 K ( T c =92 K). We observed that the pinning mechanism was changed from δ l pinning to δ T c pinning at low fields and from the catastrophic instability to a combination of the catastrophic instability and the avalanche instability at high fields with temperature.

Magnetic field and temperature dependence of intergranular activation energy in polycrystalline HgBa2Ca2Cu3O8+δ and (Tl,Pb,Bi)(Ba,Sr)2Ca2Cu3Oy superconductors

Abstract The ac susceptibilities of polycrystalline HgBa 2 Ca 2 Cu 3 O 8+ δ and (Tl,Pb,Bi)(Ba,Sr) 2 Ca 2 Cu 3 O y samples were measured as a function of temperature, magnetic field and frequency. Activation energy of both samples, obtained from Arrhenius plot for the frequency f and the maximum temperature T p in imaginary part χ ″ of ac susceptibility, approximated by U ( H , T )≈ A (1− T / T c ) H − α for temperature and field. The maximum field H p in imaginary part χ ″ of both samples showed the power-law dependence of (1− T / T c ) n for temperature range near T c .

An Experimental Investigation of the Effect of Particle Size on the Combustion Characteristics of Pulverized Sub-Bituminous Coal with Low Calorific Value by Using an LFR System

In this study, the effect of particle size on the combustion characteristics of pulverized sub-bituminous coal was experimentally investigated. A laminar-flow-entrained reactor was designed and implemented to realize the desired heating ratio and temperature corresponding to the combustion atmosphere of a pulverized-coal-fueled furnace. The flame length and structure of burning particles according to different sizes were investigated. Coal combustion processes were clearly distinguished by direct visual observation of the flame structure. The onset point of volatile ignition is greatly affected by changes in the particle size, and the burning time of the volatiles is least affected by changes in the particle size. The length and instability of char flame also increase with the increase of the particle size. However, the char consumption rate within the residential time remains nearly constant.

Relationship between superfluid density at zero temperature and Tc of Bi2Sr2−xLaxCuO6+δ (0.4 ⩽ x ⩽ 0.76) and Bi2Sr1.6La0.4Cu1−yZnyO6+δ (0.0 ⩽ y ⩽ 0.015)

We have studied the relationship between superfluid density at zero temperature,

Field and temperature dependence of effective activation energy in the grain-aligned HgBa2Ca2Cu3Oy superconductor

\rho _{s}(0)

Thermodynamics of HgBa2CaCu2O6−δ superconductor in the critical fluctuation region

, and superconducting transition temperature, T c , for the underdoped Bi 2 Sr

Magnetic field and temperature dependence of the intergranular activation energy in a polycrystalline HgBa2Ca2Cu3O8+δ superconductor

_{2-x}

Coal Ash Combustion Simulation for 500-MW Coal-firing Boiler

La x CuO 6+

ANALYSIS OF MAGNETIC CRITICAL FIELDS IN IRON-BASED SmFeAsO0.85 HIGH-Tc SUPERCONDUCTOR

_\delta

ANALYSIS OF ANISOTROPIES OF MAGNETIC HYSTERESIS AND MAGNETIC ALIGNMENT IN GRAIN ALIGNED Yb1Ba2Cu3O7-δ

and nearly optimally doped Bi 2 Sr 1.6 La 0.4 Cu