Exporting the Advanced grid in multi language

I'm trying to export advanced grid to excel with multi language support by using function

public function saveToMByteArray(codePageID: int, charSet: String);

which is used to writemultibyte(value,charset);

and exporting with this

  var xls:ExcelFile = new ExcelFile();

  xls.sheets.addItem(sheet);

  var bytes:ByteArray = xls.saveToMByteArray(54936, "GB18030"); // Simplified Chinese (4 byte); Chinese Simplified (GB18030

  var fileReference:FileReference = new FileReference();

  fileReference.save(bytes, filename+'.xls');

but i'm facing problem with conversion on excel like below .

it's converting only half of word and appending previous word char.

Can i know how it's working and converting only half of each word.??