• 한국초전도학회:학술대회논문집
• /
• 2008.08a
• /
• pp.59-59
• /
• 2008

• Journal of Magnetics
• /
• v.3 no.3
• /
• pp.86-88
• /
• 1998

A portable RF HTS SQUID-based susceptometer was used for small size magnetized sample testing in weak DC (up to 200A/m) and AC (up to 4 A/m) magnetic fields. The system resolution for the magnetic moment is of the order of $1.6{\times}10^{-10} A.m^2$. The measured DC susceptibility of a tested sample agrees well with the value obtained by using a commercial liquid helium susceptometer.

• Corrosion Science and Technology
• /
• v.3 no.5
• /
• pp.222-225
• /
• 2004

A portable RF HTS SQUID-based susceptometer was applied to the measurement of fatigue behavior for type 316L(N) stainless steel containing 0.04% to 0.15% nitrogen content. Strain-controlled low cycle fatigue (LCF) tests were conducted at RT and $600^{\circ}C$ in air an atmosphere, and the magnetic moments were measured after the fatigue test using HTS SQUID. The magnetic moment of an as-received sample is higher than that of a fatigued sample in all the temperature ranges irrespective of the nitrogen content. The fatigue life decreased with an increasing test temperature up to $500^{\circ}C$, but increased at $600^{\circ}C$. The change of the magnetic moments by LCF test is attributed to the stress induced micro defects.

• Journal of Magnetics
• /
• v.3 no.3
• /
• pp.82-85
• /
• 1998

A portable HTS RF SQUID-based system, weighing less than 20 kg has been built for susceptometry applications in weak magnetic fields, It includes a YBCO sensor for measuring the axial magnetic field component with a resolution of about $7{\times}10^{-13} T/Hz^{1/2}.$ This is determined by the intrinsic magnetic noise in the quasi-white noise region. There is a relaxation for a sudden increase in field due to magnetic flux creep in HTS. In this instance the time did not exceed 3~5 minutes.

• Applied Chemistry for Engineering
• /
• v.19 no.3
• /
• pp.316-321
• /
• 2008

Monodispersed particles of poly(styrene-co-4-vinylpyridine), poly(st-co-4vp) were prepared by soapless emulsion polymerization. Iron oxide was formed on the surface and inside of the poly(st-co-4vp) particles by thermal decompostion of iron pentacarbonyl. The obtained magnetic poly(st-co-4vp) particles was mondispersed and the average size was 250 nm. The magnetic poly(st-co-4vp) particles had 14% of iron oxide, which was identified as $Fe_3O_4$ by XRD. The magnetic poly(st-co-4vp) particles had superparamagnetism according to superconducting susceptometer (SQUID).

• Progress in Superconductivity
• /
• v.12 no.1
• /
• pp.41-45
• /
• 2010

Low temperature micro-calorimeters have been employed in the field of high resolution alpha spectrometers. These alpha detectors typically consist of a superconducting or metal absorber and a temperature sensor. The temperature sensor can be a transition edge sensor (TES), a metallic magnetic calorimeter (MMC) or other low temperature detectors for an accurate measurement of temperature change due to an alpha particle absorption. We report a recent study of the heat flow between a replaceable absorber and a temperature sensor. A piece of gold foil in $2.4{\times}2.7{\times}0.03\;mm^3$ is used as an absorber. A $40\;{\mu}m$ diameter Au:Er paramagnetic sensor is attached to another small piece of gold foil in $400{\times}200{\times}30\;{\mu}m^3$ to serve as the temperature sensor. This sensor assembly, Au:Er and gold foil, is placed on a miniature SQUID susceptometer in a gradiometric configuration. The thermal connection between the absorber and the sensor was made with three gold bonding wires. The measured thermal conductance shows a linear dependence to the temperature. The values are in a good agreement with Wiedemann-Franz type thermal conductance of the gold wires.