Abstract: The present invention provides a pharmaceutical composition for prevention or treatment of a stress disease and depression, the pharmaceutical composition be safely useable without toxicity and side effects by using an extract of leaves of Vaccinium bracteatum Thunb., which is natural resource of Korea, so that the reduction of manufacturing and production costs and the import substitution and export effects can be expected through the replacement of a raw material for preparation with a plant inhabiting in nature.

Abstract: The present disclosure relates to a multi-stage compression system in which the drive speed of each compressor that constitutes the multi-stage compression system is individually controlled to increase compression efficiency, and a control method thereof. To this end, the present disclosure includes at least two compressors, at least two driving devices connected to each of the compressors in series to drive the compressors connected in series, at least two pressure detectors installed at a discharge end of each of the compressors to detect a discharge pressure of each compressor, and a control unit configured to individually control a drive speed of each driving device based on the discharge pressure of each compressor detected through each of the pressure detectors.

Abstract: A rotor profile for a screw compressor includes a male rotor and a female rotor, which are operated in an operation space while being engaged with each other, wherein a rotor profile of the female rotor includes a curve having an operation contact point located around a pitch circle at a following-side of the female rotor, the operation contact point being contacted with the male rotor to operate the male rotor when the female rotor is operated, and the curve is configured with a quadratic function y=Lx2+Mx+N. Here, the constants L, M and N are values determined such that a slip ratio at the operation contact point is minimized. This rotor profile for a screw compressor minimizes a slip ratio at the operation contact point, thereby decreasing abrasion and reducing noise of the compressor.

Abstract: A rotor profile for a screw compressor includes a male rotor and a female rotor, which are operated in an operation space while being engaged with each other, wherein a rotor profile of the female rotor includes a curve having an operation contact point located around a pitch circle at a following-side of the female rotor, the operation contact point being contacted with the male rotor to operate the male rotor when the female rotor is operated, and the curve is configured with a quadratic function y=Lx2+Mx+N. Here, the constants L, M and N are values determined such that a slip ratio at the operation contact point is minimized. This rotor profile for a screw compressor minimizes a slip ratio at the operation contact point, thereby decreasing abrasion and reducing noise of the compressor.