gistfile1.rb

require 'nokogiri'
require 'addressable/uri'

api_key = 'your_key'

uri = Addressable::URI.parse 'http://openapi.epost.go.kr/postal/retrieveLotNumberAdressService/retrieveLotNumberAdressService/getComplexList'
uri.query_values = {
    ServiceKey: api_key,
       srchwrd: '무악동',
        areaNm: '현대아파트',
      searchSe: 'and'
}

response = `curl #{uri}`

doc = Nokogiri::XML( open(uri) )