This paper reports the following two topics : $circled1$ ozone concentration (O$sub$3con/) and discharge characteristics in flowing O$sub$2/ with variation of Re$sub$3/ at high voltage nozzle (HVN) of HVN 10 type ozonizer. $circled2$ O$sub$3con/ with variation of Re$sub$3/ at HVN of HVN 25 type ozonizer. The important conclusions obtained from this paper are as follows. 1) In HVN 10 type ozonizer : $circled1$ The discharge pattern can be controlled by adjustment of the Re$sub$3/. $circled2$ V$sub$c/ is inversely proportional to pulse width (P$sub$w/) and pulse frequency (P$sub$f) $circled3$ O$sub$3con/ increase as decreasing of Re$sub$3/ for constant P$sub$w/ and P$sub$f/. $circled4$ O$sub$3con/ increase as decreasing of P$sub$w/, O$sub$3con/ is proportional to P$sub$f/. 2) In HVN 25 type ozonizer : O$sub$3con/ of HVN 25 type ozonizer can increase than that of HVN 10 type ozonizer, according to parallel circuit of applied voltage and serial of supplied gas. As a result, we can obtain O$sub$3con/ of 825[ppm] as the maximun value.