Dear Stanislav,
Now I am lookig at Metalink note 788156.1.
I think you are right stored data is in different character set from the DB.
But I need to find out how to convert improper data. Is there any way to check table contents?
I have posted result of SELECT * FROM NLS_DATABASE_PARAMETERS below
NLS_NCHAR_CHARACTERSET-->UTF8
NLS_LANGUAGE-->AMERICAN
NLS_TERRITORY-->AMERICA
NLS_CURRENCY-->$
NLS_ISO_CURRENCY-->AMERICA
NLS_NUMERIC_CHARACTERS-->.,
NLS_CHARACTERSET-->UTF8
NLS_CALENDAR-->GREGORIAN
NLS_DATE_FORMAT-->DD-MON-RR
NLS_DATE_LANGUAGE-->AMERICAN
NLS_SORT-->BINARY
NLS_TIME_FORMAT-->HH.MI.SSXFF-->AM
NLS_TIMESTAMP_FORMAT-->DD-MON-RR-->HH.MI.SSXFF-->AM
NLS_TIME_TZ_FORMAT-->HH.MI.SSXFF-->AM-->TZR
NLS_TIMESTAMP_TZ_FORMAT-->DD-MON-RR-->HH.MI.SSXFF-->AM-->TZR
NLS_DUAL_CURRENCY-->$
NLS_COMP-->BINARY
NLS_LENGTH_SEMANTICS-->BYTE
NLS_NCHAR_CONV_EXCP-->FALSE
NLS_RDBMS_VERSION-->10.2.0.4.0