code: @Override
  	public String getPopUpURL(String CorpNum, String NTSConfirmNum) throws PopbillException {
  		if ( NTSConfirmNum.length() != 24 )
  			throw new PopbillException(-99999999, "국세청승인번호가 올바르지 않았습니다.");
  		URLResponse response = httpget("/HomeTax/Taxinvoice/" +NTSConfirmNum+"/PopUp", CorpNum, null, URLResponse.class);
  		
  		return response.url;
  	}
docs: /*
  (non-Javadoc)
  @see com.popbill.api.HTTaxinvoiceService#getPopUpURL(java.lang.String, java.lang.String)