We present time-resolved CCD photometry of a dwarf nova NSV 4838 ( UMa 8 , SDSS J102320.27+440509.8 ) during the 2005 June and 2007 February outburst .
Both light curves showed superhumps with a mean period of 0.0699 ( 1 ) days for the 2005 outburst and 0.069824 ( 83 ) days for the 2007 outburst , respectively .
Using its known orbital period of 0.0678 days , we estimated the mass ratio of the system to be q =0.13 based on an empirical relation .
Although the majority of SU UMa-type dwarf novae having similar superhump periods show negative period derivatives , we found that the superhump period increased at \dot { P } / P _ { sh } =+7 ( +3 , -4 ) \times 10 ^ { -5 } during the 2007 superoutburst .
We also investigated long-term light curves of NSV 4838 , from which we derived 340 days as a supercycle of this system .