Abstract: A hammer system for automatically carrying out a standard penetration test is disclosed. A cylindrical housing, in which an anvil coupled to a drill rod is received, is supported by a first hydraulic cylinder coupled to boring equipment. A cylindrical hammer is received in the housing. The hammer includes a holding assembly therein, which selectively holds and raises the hammer by a second hydraulic cylinder. Element for limiting a stroke of the hammer is spacedly connected to the holding assembly to be raised and lowered therewith. The limiting element includes a first sensor to detect a slot formed at the housing when the hammer is raised, thereby counting the number of blows. The hammer includes a plurality of protrusions on its outer surface. A wall of the housing includes a second sensor to detect the number of protrusions passed over the second sensor when the hammer is raised, thereby calculating a penetration depth from a difference between the numbers of protrusions detected for two continuous blows.

Abstract: A hammer system for automatically carrying out a standard penetration test is disclosed. A cylindrical housing, in which an anvil coupled to a drill rod is received, is supported by a first hydraulic cylinder coupled to boring equipment. A cylindrical hammer is received in the housing. The hammer includes a holding assembly therein, which selectively holds and raises the hammer by a second hydraulic cylinder. Means for limiting a stroke of the hammer is spacedly connected to the holding assembly to be raised and lowered therewith. The limiting means includes a first sensor to detect a slot formed at the housing when the hammer is raised, thereby counting the number of blows. The hammer includes a plurality of protrusions on its outer surface. A wall of the housing includes a second sensor to detect the number of protrusions passed over the second sensor when the hammer is raised, thereby calculating a penetration depth from a difference between the numbers of protrusions detected for two continuous blows.

Abstract: A copolyester resin having excellent physical properties and a low acetaldehyde content is produced by: polycondensing a mixture of terephthalic acid and isophthalic acid with a glycol in the presence of a phosphate compound to prepare a copolyester prepolymer having an intrinsic viscosity of more than 0.5 dl/g; subjecting the copolyester prepolymer to a first heat-treatment to obtain a pre-crystallized resin; and subjecting the pre-crystallized resin to a second heat-treatment, to obtain a copolyester resin having an intrinsic viscosity of 0.62 to 0.80 dl/g and a melting point of 190.degree. to 240.degree. C.

Abstract: A biaxilly oriented polymer film having improved surface properties, anti-static property and printability is prepared from a mixture of 70 to 99 parts by weight of a polyester resin containing not less than 60% by weight of repeating units of ethylene terephthalate and having an intrinsic viscosity ranging from 0.4 to 0.9 dl/g, and 1 to 30 parts by weight of polyolefin resin having a melting flow index ranging from 1.5 to 25 g/10 min, wherein said polyester film further comprises 0.1 to 25 parts by weight of an inorganic particle.

Abstract: A white-colored porous polymer film having elongated spherical pores, which is characterized in that said pores exposed on a surface created by cutting the film along longitudinal direction satisfy the following formulae, possesses a low density, good surface and mechanical property and good processability: ##EQU1## wherein, P.sub.L,90 is an average length of longer axes of 90% or more of the exposed pores;P.sub.D,90 is an average length of shorter axes of 90% or more of the exposed pores;P.sub.L/D,50 is an average of the longer axis to the shorter axis length ratios of the exposed pores;P.sub.N is the number of exposed pores per 1000 .mu.m.sup.2 of the exposed surface; andP.sub.A is the ratio of the exposed pore area to the exposed surface area.The polymer film of the present invention comprises a polyester and polyolefin resin mixture, inorganic particles, a metal sulfonate and a hindered phenol.

Abstract: A polymeric film, which comprises 100 parts by weight of a polyester resin having an intrinsic viscosity ranging from 0.4 to 0.9 dl/g, 5 to 50 parts by weight of a polyolefin resin having a melt flow index ranging from 1.0 to 25 g/10 min and/or a styrene resin having a melt flow index ranging from 1.5 to 20 g/10 min, and 0.01 to 1.0 part by weight of a metal sulfonate of the following formula (I) having an acid value of 1.0 mg KOH/g or less, has an excellent antistatic property, printability, a good appearance and touchiness, as well as an improved film characteristics such as bulk density and heat stability.R.sub.1 --C.sub.6 H.sub.4 --SO.sub.3 Me (I)wherein,R.sub.1 is a C.sub.5 -C.sub.20 alkyl group; andMe is an alkali metal or alkali earth metal.