First of all, Under given condition such as bit gage of 36mm Drill bit with right class of jack-logs experimental test carried out from two face of Bench, firing of each hole brought 90 degree Angle face and them measured length of Burden and charged ammount of powder as following. (equation omitted) A=Activated Area A=ndi=m S=Peripheral length of Charged. room Ca=Rock Coeffiecency d : di=Hole diameter When constructed subway of Seoul in 1980 the blasting works increased complaint of ground vibration. in order to prevent the damage to structures. Some empirical equations were made as follows on condition with Jackleg Drill (Bit Gage ø 36mm) and within 30 meter distance between blasting site and structures. V=K(D / W)$\^$-n/ N=1.60-1.78 K=48-138 Project one of contineous works to above a determination of empirical equation on the cautious blasting vibration with Crawler Drill(ø 70-75mm) in long distance. V=41(equation omitted) V=124(equation omitted).

The effect of firing on the development of strength of china with maturing range of a series of glaze that gave no defect on firing was observed in an electrical furnace and oil-fired kiln. The body formular is as follows (equation omitted), and it was applied to a selected china body. Porcelain glaze formular is in the following. (equation omitted) The result obtained is sumarized as follows : (1) It was found that the strength of porcelain increases when the A1$_2$O$_3$ moles of the glaze increses, and the strength of porcelain decreases when the SiO$_2$ moles of glaze decreases at 3.9-5.9 moles, and increases again when the SiO$_2$ moles increases at 5.9-7.9 notes. (2) It was found the most safe glaze is No. 25 glaze.