When non english colnames(korean charater), cannot db_insert_into. . .
I couldn't find any solution 
library(tidyverse)
library(RSQLite)
df<-data.frame(가=1:3)
con<-dbConnect(SQLite(),'mydb.sqlite')
copy_to(con,df, 'tbl1')
df2<-data.frame(가=4:6)
db_insert_into(con,'tbl1',df2)
# error message such as
# tolower(colnames)... multybyte string ...