In this study, plasma shot (PS) treatment was applied to high-speed steel (HSS) surfaces using a titanium carbide electrode to confirm the effect of discharge current (I p) on the formation of a single dimple and analyze a modified layer. The roughness of modified surfaces increased when I p increased, and energy-dispersive X-ray spectrometry showed an increase in titanium atom density when I p and electrode consumption volume (V e) increased. A friction test confirmed that the modified surface's friction was reduced by discharge dimples under low-load conditions. Vickers hardness test confirmed that the hardness of the modified surface was ~ 300-600 HV higher than that of an untreated HSS surface. Moreover, it increased with an increase in I p. However, application of PS treatment to the edge of surfaces on the workpiece caused shape deterioration. The deterioration size of the edge of the modified layer increased when I p increased. To solve this issue, we propose a novel method named position-adjusted PS (PA-PS) treatment. PA-PS treatment is used to adjust the end of the electrode in the order of tens of micrometers from the edge of the workpiece to avoid the deterioration of the edge form. Under I p = 21 A, PA-PS formed a modified layer without deteriorating the edge shape of the workpiece, thus confirming the PS characteristics applied to HSS surfaces. Moreover, PA-PS treatment solved the shape deterioration of the edge on modified surfaces via PS treatment.

A new correlated double sampling method for two-dimensional magnetic sensors was proposed. In this method, output from a magnetic sensor is controlled by adjusting the drain bias of a MOSFET used as a Hall element. The two-dimensional integrated magnetic sensor used for the demonstration of correlated double sampling was composed of a 64 × 64 array of Hall sensors and fabricated by a 0.18 µm CMOS standard process. The size of a Hall element was 2.7 × 2.7 µm2. The dimensions of one pixel in which a Hall element was embedded were 7 × 7 µm2. The magnitude of residual noise after correlated double sampling with drain bias control was 0.81 mVp–p. This value is 16% of the original low-frequency noise. From the experimental results, the proposed correlated double sampling method is found to be suitable for low-frequency noise suppression in the two-dimensional magnetic sensors.