ConvertUTF8

   public string ConvertUTF8(string strBig5)
  {
   Encoding utf81 = Encoding.GetEncoding("utf-8");
   Encoding big51 = Encoding.GetEncoding("big5");
   byte [] strbig51= big51.GetBytes(strBig5);
   byte [] strUtf81 = Encoding.Convert(big51,utf81, strbig51);
   char[] utf8Chars =new char[utf81.GetCharCount(strUtf81, 0, strUtf81.Length)];
   utf81.GetChars(strUtf81, 0, strUtf81.Length, utf8Chars, 0)
   string tempString = new string(utf8Chars);
   return tempString;
  }