IANAAppCodePage=106 [ and is set in the Extended Options field for the datasource using ODBC Adminidtrator]:

a] Open ODBC Test ( ANSI )
b] Connect to a ProstgreSQL data source
c] Create a table
CREATE TABLE T_VARCHAR3 (F_INT integer NOT NULL,F_VARCHAR varchar(255) NULL)
d] Update the table
UPDATE T_VARCHAR3 SET F_VARCHAR = 'PCI_PCI 익스프레스 x8 확장 이중-x4 3Gb SAS 어댑터' WHERE F_INT = :0
e] Run a select query on the table
SELECT G_TS1.F_INT, G_TS1.F_VARCHAR FROM T_VARCHAR3 G_TS1
f] Output observed:  PCI_PCI ì�µìŠ¤í”„ë ˆìŠ¤ x8 확장 ì�´ì¤‘-x4 3Gb SAS 어댑터 
Output expected: PCI_PCI 익스프레스 x8 확장 이중-x4 3Gb SAS 어댑터

DataDirect Connect for ODBC PostgreSQL and Sybase driver are unicode drivers ( i.e. these drivers can understand "W" function calls and the Driver Manager can pass them through to the driver without conversion to ANSI and the driver has the capacity to interpret Unicode function calls without the intervention of the Driver Manager.

The Unicode driver , must convert SQL_C_CHAR (ANSI) data to SQL_WCHAR (Unicode) data, and vice versa, as well as SQL_C_WCHAR (Unicode) data to SQL_CHAR (ANSI) data, and vice versa. The driver must use client code page information i.e Active Code Page on Windows ( in this case it is overridden to use the IANAAppCodePage value on Windows) to determine which ANSI code page to use for the conversions. The Active Code Page or IANAAppCodePage must match the database default character encoding; if it does not, conversion errors are possible.

Parameterized queries work with the ANSI application involving unicode characters because , the parameterized query (SQL_C_CHAR functions) are passed on to the Driver directly and there is no intervention by the Driver Manager . The driver uses the IANAAppCodePage setting in the connection option for conversion.

Literal queries (non parameterized) return junk value with the ANSI Application because the Microsoft Driver Manager intervenes for conversion and uses the client machines Active Code Page.[IANAAppCodePage is a setting on the driver and cannot be used by the Microsoft Driver Manager ]
i.e. In other words , arguments to ODBC functions get converted( i.e. queries using literals get converted) and the Microsoft Driver Manager intervenes for the conversion.

Hence different results are observed  with parameterized queries versus queries using literals when using the DataDirect unicode drivers with an ANSI application involving unicode data.