function swap_image(target_object, flag) {
    var id_ph_interview = 'ph_interview' + target_object;
    var id_go_interview = 'go_interview' + target_object;

    var src_ph_interview = 'image/ph_interview' + target_object + '_top';
    var src_go_interview = 'image/btn_go_interview';

    if (flag == 'on') {
        src_ph_interview += '_on';
        src_go_interview += '_on';
    }

    document.getElementById(id_ph_interview).src = src_ph_interview + '.jpg';
    document.getElementById(id_go_interview).src = src_go_interview + '.gif';
}