public bool Login()
        {
            string postdata = string.Format("m=login&nextURL=http%3A%2F%2Fwww.ijji.com%2Findex.nhn&memberid={0}&password={1}", encode(Username), encode(Password));
            string result = post(_url + "login.nhn", postdata);
            return !(result.Contains("You have entered an incorrect password") || result.Contains("User ID is not found"));
        }
        public string GetCookies() { return Cookies.GetCookieHeader(new Uri("http://ijji.com/")); }

if (Logins.Login())
                {
                    IDC_Browse.Navigate("javascript:cookie=\"" + Logins.GetCookies() + "\";"); // <-- that line
                    IDC_Browse.Navigate("javascript:goPlay('u_gunz', '');");
                }