Kwang Min Yu

All-around dual source impedance bridge

Two terminal dual source impedance bridge was configured using commercial voltage calibrators. The bridge performance was evaluated by measuring 1 to 1 resistance ratio at 1 kHz using 1 kΩ and 10 kΩ resistors. The same bridge was used for the resistance (R) to the inductor (L) and the capacitor (C) ratio measurements by adjusting the phase between the voltage sources. Then, the AC resistance value was found from the R : C ratio. This simple two terminal dual source impedance bridge proved its reliable and versatile measurement capability.

Modified Step-Up Method for Calibration of DC High-Voltage Dividers

The dc high voltage is usually measured with high-voltage divider which plays the role of the ratio standard linking the unknown high voltage to the well-known low-voltage standards. A step-up method had been proposed to calibrate the dividing ratios of the high-voltage dividers at nominal test voltage. The step-up technique has been newly modified for improving the transfer accuracy of reference values determined in voltage stack stage, with employing an additional source voltage monitoring device, and successfully applied to precisely determine the dividing ratios up to 100 kV. Typical standard uncertainty for the dividing ratios is estimated to be approximately

Modified step-up technique for the DC high voltage traceability

5 \times 10^{{ {-6}}}

A method for measuring high resistances with negligible leakage effect using one voltage source and one voltmeter

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Precise Measurement of Quantized Hall Resistance on the Basis of a Cryogenic Current Comparator

The DC high voltage is usually measured with high voltage divider which plays the role of the ratio standard linking the unknown high voltage (HV) to the well-known low voltage standard. Step-up method had been proposed to link the HV measurements to the low voltage standard. This paper describes the improved step-up technique, which employs an additional source voltage monitoring device. The monitoring tool has been successfully applied for the step-up techniques to determine the dividing ratios of the high voltage dividers up to 100 kV.

Comparisons of Precision Measurement Methods for Metallic Resistivities

We present a method for measuring high resistances using one voltage source and one voltmeter. With this method, there exist two techniques. One is to measure a high resistance with a much lower resistance and the other is to cancel the leakage effect effectively using two nominally equal resistances without an auxiliary guarding apparatus. To demonstrate the methods validity, a 1 GΩ resistance was measured using the two techniques replacing a dummy 1 GΩ resistance as a leakage resistance; the measurement results agree well with the theoretical results within the measurement uncertainty of 3 × 10−6 (k = 2) level. We used the method to determine 10 MΩ, 1 GΩ and 1 TΩ resistances with an active-guard type and a T-type. The best expanded uncertainties at k = 2 from the results were estimated as 0.3 × 10−6, 0.8 × 10−6 and 20 × 10−6, respectively. We also show that while the expanded uncertainty of 70 × 10−6 is obtained using an 81/2 digit digital multimeter, it is improved to 20 × 10−6 using an electrometer with high-input resistance, low bias current and high resolution when the second technique is used to measure high resistances.

Effect of temporary temperature change on drift rate of KRISS legal ohm

We report on the setup of an accurate quantized Hall effect measurement system including a homemade cryogenic current comparator system, a He‐3 bath cryostat with a 12 T superconducting magnet and a homemade air bath with a temperature stability of 0.005 °C at 23.000 °C. The performance of the system was verified through calibration of a standard resistor of 100 Ω against the quantized Hall resistance (QHR) at plateau i = 2, RH(2) = 12.9 kΩ. The reproducibility of the QHR measurements is reliable at a relative uncertainty of few parts in 109.

An AC-DC resistor based on a silicon wafer

As widely-used methods to measure metallic resistivities, Four-terminal method, van der Pauw method, Four-Point Probe(FPP) method and eddy current method were compared and analysed to find the method with lowest uncertainty and accurate method for applying nondestructively to industry. STS 316, non-magnetic metal is used as sample for the four methods. Conductivity ratios by the four-terminal method and van der Pauw method had the lowest uncertainty of 0.25 % and the ratios by the FPP method had measurement uncertainty of 0.45 % when probe spacing was more than two times of sample thickness and dc 10 A is applied. Also, the ratio values by the eddy current method had 1 % or more difference from the four-terminal or van der Pauw method and measurement uncertainty was obtained as 0.93 %. From the results, former two methods had the lowest uncertainty but are destructive methods so that those are difficult to apply to the field of industry. The FPP method is an accurate and nondestructive measurement method so that it can be used in the field. The eddy current method is one of nondestructive method but it has the highest uncertainty and low accuracy.

Third generation of adapted wheatstone bridge for high resistance measurements at NIST

The abnormal drift rate of Thomas type 1 ohm resistors according to temporary temperature change is described and they are compared with NML 1 ohm resistors with almost the same drift rate. It is thought that the major origin of difference between the two types is the coil-mounting structure suffering from stress.

APMP key comparison for the 10 MΩ and 1 GΩ resistance

An ac-dc resistor based on a silicon wafer is suggested. A resistance ratio is deduced from two resistances of the wafer given by van der Pauw theorem and Thompson-Lampard theorem. The ratio is a constant value, (π/ln2)2 and does not depend on electrical resistivity and other parameters. A simulation for dc current density to measure the two resistances was compared. Also, the two resistances were measured at dc and the measured resistance ratio is roughly in agreement with the calculated resistance ratio. We suppose that the concept can also be used for other ranges.