add_filter( 'gform_currencies', 'add_inr_currency' );
function add_inr_currency( $currencies ) {
    $currencies['INR'] = array(
        'name'               => __( '대한민국 원', 'gravityforms' ),
        'symbol_left'        => '₩',
        'symbol_right'       => '',
        'symbol_padding'     => ' ',
        'thousand_separator' => ',',
        'decimal_separator'  => '.',
        'decimals'           => 2
    );
 
    return $currencies;
}