  In this paper we present for the first time, the study of low resolution $H$-
and $K$- band spectra of 7 DY\,Per type and suspects stars as well as
DY\,Persei itself. We also observed $H$- and $K$- band spectra of 3 R Coronae
Borealis (RCB) stars, 1 hydrogen-deficient carbon (HdC) star and 14 cool carbon
stars including normal giants as comparisons. High $^{12}$C/$^{13}$C and low
$^{16}$O/$^{18}$O ratios are characteristic features of majority RCBs and HdCs.
We have estimated $^{16}$O/$^{18}$O ratios of the programme stars from the
relative strengths of the $^{12}$C$^{16}$O and $^{12}$C$^{18}$O molecular bands
observed in $K$- band. Our preliminary analysis suggest that a quartet of the
DY\,Per suspects along with DY\,Persei itself seems to show isotopic ratio
strength consistent with the ones of RCB/HdC stars whereas two of them do not
show significant $^{13}$C and $^{18}$O in their atmospheres. Our analysis
provides further indications that DY\,Per type stars could be related to
RCB/HdC class of stars.
