Abstract: The present invention relates to a process for preparing a water absorbent resin, particularly to a process for preparing a water absorbent resin which can resolve the uneven size of the fine pulverized gel-type resin and long pulverizing time those are the problems of prior process for preparing the water absorbent resin, by carrying out the pulverizing process of the gel-type resin divided into the coarse pulverizing process which is carried out with the internal cross-linking polymerization, and the fine pulverizing process. According to the preparation process, it is possible to mass-produce the water absorbent resin showing excellent absorption under pressure and low extractable content.

Abstract: The present invention relates to a bullet including an air-guiding recess, comprising: a head 20; and a tail 30 disposed behind the head 20, and including an odd number of air-guiding recesses 32 formed so as to be curved in the bottom and outer circumferential surfaces thereof. The air-guiding recess 32 is characterized by having a sloped bottom that increases in depth while progressing to the bottom surface of the tail 30. Accordingly, vortex is prevented from being generated at the rear side of the bullet, so as to significantly increase the effective range thereof and simultaneously improve accuracy when shooting same.

Abstract: The present invention relates to an absorbent resin surface-modified with a cationic polymer compound. According to the present invention, the use of a cationic polymer compound can provide a simple and economical way to prepare an absorbent resin surface-modified with a cationic polymer compound with enhanced absorption rate and absorbency, overcoming the problem with the conventional absorbent resin having low absorption rate and poor absorbency.

Abstract: The present invention relates to a process for preparing a water absorbent resin, particularly to a process for preparing a water absorbent resin which can resolve the uneven size of the fine pulverized gel-type resin and long pulverizing time those are the problems of prior process for preparing the water absorbent resin, by carrying out the pulverizing process of the gel-type resin divided into the coarse pulverizing process which is carried out with the internal cross-linking polymerization, and the fine pulverizing process. According to the preparation process, it is possible to mass-produce the water absorbent resin showing excellent absorption under pressure and low extractable content.

Abstract: Disclosed is an optical filter switching apparatus used in an optical instrument for converting externally input image information into video image information and outputting the video image information. The apparatus comprises: an optical filter holding section holding a first optical filter and a second optical filter; an actuator having a rotary solenoid which rotates between a first position and a second position. A rotational power transmission section transmits the rotational force of the rotary solenoid to the optical filter holding section; and a microprocessor controls the rotary solenoid of the actuator in accordance with at least one external input signal and the power level of the video image information. The rotary solenoid is rotated to at least one of the first and second positions.

Abstract: Disclosed is an optical filter switching apparatus used in an optical instrument for converting externally input image information into video image information and outputting the video image information. The apparatus comprises: an optical filter holding section holding a first optical filter and a second optical filter; an actuator having a rotary solenoid which rotates between a first position and a second position. A rotational power transmission section transmits the rotational force of the rotary solenoid to the optical filter holding section; and a microprocessor controls the rotary solenoid of the actuator in accordance with at least one external input signal and the power level of the video image information. The rotary solenoid is rotated to at least one of the first and second positions.