Oracle 10g - Chinese Character In New Columns

I am using Oracle 10g version and I have a database created and it contains around 9 tables and 25k records, as per my current requirement I need to add few more columns in the existing tables and those new columns are going to be filled with contents from multiple languages (as of now Chinese and English). I went through Oracle 10g globalization guide and I understood that, for my requirements I need to add my new columns with data types of either NVARCHAR or NCHAR.

With my about understanding I created the following table and tried to insert some Chinese characters as follows but it's now coming as expected and I'm getting inserted only "????" in my table columns

Find below the list of actions

>create table Employee(EmpId varchar(255), EmpName NCHAR(255));
>insert into Employee(EmpId, EmpName) values('280129','彭俊睦');
>select * from Employee;
280129 ¿¿¿

>insert into Employee(EmpId, EmpName) values('28018',N'彭俊睦');
>select * from Employee;
280129 ¿¿¿
28018 ¿¿¿

When I run the “select * from v$nls_parameters;” query I’m getting the following data

NLS_LANGUAGE ---------à SIMPLIFIED CHINESE
NLS_TERRITORY---------à AMERICA
NLS_CURRENCY---------à $
NLS_ISO_CURRENCY---------à AMERICA
NLS_NUMERIC_CHARACTERS---------à .,
NLS_CALENDAR---------à GREGORIAN
NLS_DATE_FORMAT---------à DD-MON-RR
[Code] .....