imageDir <- 'p:\\tmp\\plots';
image_filename = tempfile(pattern = "plot_", tmpdir = imageDir, fileext = ".png")
png(filename=image_filename, units="mm", width=250, height=250, res=300) #진하고 선명하게 그려진다.

wordcloud(mydata$word, mydata$freq, scale=c(5,0.75), max.words=100, min.freq=1, random.order=FALSE, rot.per=0.35, use.r.layout=FALSE, colors=brewer.pal(8, "Dark2"))

dev.off();

#참고
#word_plot <- paste(readBin(file(image_filename, "rb"), what=raw(), n=1e6), collapse="") #binary로 바꿔주는거