소스코드 및 원문: https://www.ibm.com/developerworks/mydeveloperworks/blogs/9e635b49-09e9-4c23-8999-a4d461aeace2/entry/277?lang=ko httpv://www.youtube.com/watch?v=SOfhE_Dt-f4&feature=player_embedded httpv://www.youtube.com/watch?v=2qHE734VPZA&feature=player_embedded