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권성원,조용명,김규태,강전홍,박영태 ( Sung Won Kwon,Y . M . Cho,K . T . Kim,J . H . Kang Y . T . Park ) 한국센서학회 1998 센서학회지 Vol.7 No.6
A dual-channel automatic ac-do voltage transfer error measurement system in which the output voltages of two thermal voltage converters which are ac voltage standard are directly measured at the same time to reduce the output voltage drift is described. Forward-reverse measurement method by using a two-channel scanner is used to cancel the offset voltage of the voltmeters. The agreements of the 4-V TVC comparison results between other national standards institute and Korea Research Institute of Standards and Science were less than about ±2 ppm in the frequency range of 40 Hz∼100 kHz, and were less than about ±4 ppm at 200 kHz∼1 MHz. Measurement uncertainty is reduced significantly from ?5 ppm of manual system to ±3 ppm of new system(up to 100 kHz) typically and great increase in comparison efficiency has been achieved by this system.
권성원 ( Sung Won Kwon ),박세일 ( S . I . Park ),조용명 ( Y . M . Cho ),강전홍 ( J . H . Kang ) 한국센서학회 1996 센서학회지 Vol.5 No.4
Planar multi-junction thermal converters were fabricated for precise measurements of the ac voltage and current by an ac-do transfer method. A heater and a thermocouple array were fabricated onto a sandwiched membrane, Si₃N₄ (200 nm) / SiO₂(400 nm) / Si₃N₄(200 nm, a thickness of 0.8 ㎛ and a size of 2 x 4 ㎟, which is supported by a surrounding frame. The NiCr heater is located at the center of the membrane vertically. Hot junctions of 48 ∼ 156 pairs of thermocouples (Cu-CuNi44) are located near or onto the heater, and cold junctions are located onto the silicon frame. Output of the thermal converters for 10 mA do input was 76 mV ∼ 382 mV dependent on a model, and short term stability of the outputs was ±5 ∼ 15 ppm/ 10 min with 5 mA do input. Responsivity in air was in the range of 3.9 ∼ 14.5 V/W. Responsivity of the model BF48 in air which has 48 thermocouples was 2 times or greater than that of 3 dimensional multi-junction thermal converter in vacuum which has 56 thermocouples. AC-DC transfer differences with an input of 10 mA or less were less than ±1 ppm in the frequency range from 5 Hz to 2 kHz, and about 2 ∼ 3 ppm at 5 kHz and 10 kHz.