<UML> Reference Site:
Inheritance: ㅡㅡㅡㅡㅡD
Interface: - - - - - - D
association(has): A ㅡㅡㅡㅡㅡ> B class A { member B}
Leg <.>-----> 필수.
Flea <>------>
dependency: A - - - - - > B class A uses B temporary.
<Gof Pattern> Reference SIte
Creational Pattern: Singleton, (Abstract)Factory, Builder, Prototype
Structral Pattern: Adapter, Decorator, Bridge, Proxy
Behavior Pattern: Command, Iterator, Visitor, Observer, Chain of Responsibility
