elixir, 191 bytes

Result

AC

Duration

2531ms

Code [DL]

a=String.split IO.read(:all),"
",trim: true
Enum.each a,fn x->IO.puts Regex.replace ~r/K *T/,String.slice(x,0,:binary.match(hd(a),"T")|>elem(0))<>"T",&(String.duplicate("K",byte_size(&1)))end

stdin

                        T                         
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
         K                                        

stdout

                        T
                        T
                        T
                        T
                        T
                        T
                        T
                        T
                        T
                        T
                        T
                        T
                        T
                        T
                        T
                        T
                        T
                        T
                        T
                        T
                        T
                        T
         KKKKKKKKKKKKKKKK

stderr

strace