Abstract: Provided are an indoor gas detecting apparatus and an indoor air purification system. The indoor gas detecting apparatus includes: a gas sensor unit composed of a plurality of gas sensors and a fine dust sensor; a controller controlling overall operations; a display unit; an alarm unit; and a communication unit transmitting/receiving data to/from an external apparatus. If a detected gas amount exceeds a predetermined permission level of each gas, the controller transmits an operation signal to an external automatic gas blocking apparatus or an external air purification apparatus so as to operate the automatic gas blocking apparatus or the air purification apparatus. Accordingly, not only fresh indoor air can be maintained but also an explosion or a fire can be prevented.

Abstract: A water-based cutting fluid includes a water-soluble polymer dissolved in water and ceramic powder dispersed in the water. The cutting fluid further includes water glass. Further, the water-soluble polymer is one selected from a group consisting of polyvinyl alcohol (PVA), cellulose, methyl cellulose, carboxymethyl cellulose (CMC), starch, or a combination thereof.