Abstract: A magnetic marker of the present invention includes a magnetic thin wire for generating pulses and bodies of soft magnetic materials that are arranged close to the two ends of the thin wire that have a smaller coercive force than the magnetic thin wire. The magnetic thin wire has a diameter of 60-115 .mu.m and has a ratio of B.sub.r /B.sub.s of a B-H loop of 0.8 or more. Thus, a small magnetic marker can be formed which provides a large Barkhausen effect even if it contains a very short magnetic thin wire.

Abstract: A method for measuring properties of a cold rolled thin steel sheet, comprising the determination, by using a resonant electromagnetic ultrasonic wave sensor for a standing wave, of the ratio of a thickness resonant frequency of a transverse ultrasonic wave propagating within a cold rolled thin steel sheet in the direction of thickness while polarized in a direction parallel to the direction of rolling to a thickness resonant frequency of a longitudinal ultrasonic wave propagating within the cold rolled thin steel sheet in the direction of thickness, and the ratio of a resonant frequency of a transverse ultrasonic wave propagating within the cold rolled thin steel sheet in the direction of thickness while polarized in a direction normal to the direction of rolling to a thickness resonant frequency of a longitudinal ultrasonic wave propagating in the direction of thickness, and approximately determining the Young's modulus and the Lankford value according to a computing formula using the resultant two measured

Abstract: A method of and apparatus for measuring the degree of transformation of the structure of an object. An object is placed between a transmission coil and a receiving coil. An A.C. current or a pulse current or a combination of the A.C. current and the pulse current are supplied to the transmission coil, and the degree of transformation is detected by means of an electric signal obtained through the receiving coil.

Abstract: A continuous casting mold having the wall thickness of each of parts corresponding to a point where molten steel begins to solidify during continuous casting is arranged to be locally thinner than other parts of the mold. High frequency oscillation is applied to the locally thinned parts to vibrate them to a sufficient amplitude to prevent the seizure of a cast steel piece from taking place due to the heat thereof for improvement in the surface quality thereof.

Abstract: In a method for continuous casting of steel, a slab having good quality is obtained by inspecting the profile of the unsolidified region of the slab in the transverse direction thereof during casting and controlling the cooling pattern so that the profile matches a pre-determined standard profile.

Abstract: An apparatus for generating and detecting an electromagnetic ultrasonic wave in which a magnetic field generator forms a magnetic field at the surface area of one side of a conductive material, and an eddy current and impulse of a magnetic field are produced in the surface area by supplying a high frequency current pulse to an ultrasonic wave generating coil, the interaction therebetween producing an ultrasonic wave which travels in the conductive material and further, the eddy current resulting from the interaction between the formed magnetic field and a reflected ultrasonic wave being reflected by another side of the conductive material or the internal defect contained therein is detected by a detecting coil which is electromagnetically separated from the ultrasonic wave generating coil by a decoupling means.