Abstract: An embodiment core molding system includes an upper hopper partitioned to define a first accommodating part that accommodates first core sand coated with an organic binder and a second accommodating part that accommodates pure sand, a lower hopper disposed under the upper hopper and connected to the first and second accommodating parts, the lower hopper being configured to measure weights of the first core sand and the pure sand, a mixer connected to the lower hopper, wherein the mixer is configured to allow the first core sand to pass directly therethrough and to accommodate the pure sand, a binder supply unit connected to the mixer and configured to supply an inorganic binder into the mixer, and a core mold configured to mold each of the first core sand and second core sand into a preset shape, the second core sand including the pure sand coated with the inorganic binder.

Abstract: A central maintenance apparatus of sensor for geophysical exploration includes a body part cylindrically formed to wrap a circumference of a sensor rod; and a plurality of wing parts lengthwise formed at an outer wall of the body part in a convex, semi-elliptic shape with a predetermined width, and formed therein with a cavity, wherein the wing part is formed with a plurality of through holes passing through the cavity from an outside, and has a shape-changing elasticity when a pressure is applied to a direction of the body part. At this time, when an obstacle is encountered while moving inside a borehole, the wing part having a shape-changing elasticity can avoid the obstacle like sliding off the obstacle to allow the central maintenance apparatus of sensor to automatically rotate.

Abstract: A magnetic sensor for borehole magnetometer includes an upper-opened pipe-shaped housing; a frame installed at an inside of the housing; an upper-opened magnetic sensor part installed at a bottom side of the frame; a lid covering the opened upper side of the magnetic sensor part; and a magnetic sensor disposed at an inside of the magnetic sensor part to measure a magnetic force, wherein an upper side and a bottom side of the magnetic sensor is respectively installed with a spring, a bottom side of the lid and the magnetic sensor part are formed with a fixing groove for fixing an upper spring and a bottom spring each installed at an upper side and a bottom side of the magnetic sensor.

Abstract: A magnetic sensor for borehole magnetometer includes an upper-opened pipe-shaped housing; a frame installed at an inside of the housing; an upper-opened magnetic sensor part installed at a bottom side of the frame; a lid covering the opened upper side of the magnetic sensor part; and a magnetic sensor disposed at an inside of the magnetic sensor part to measure a magnetic force, wherein an upper side and a bottom side of the magnetic sensor is respectively installed with a spring, a bottom side of the lid and the magnetic sensor part are formed with a fixing groove for fixing an upper spring and a bottom spring each installed at an upper side and a bottom side of the magnetic sensor.