temp 변수로 임시저장해서 참조하던 방식을, bind() 메서드를 통해 scope이식하는 방식으로 리팩토링
Refactoring Transfer "this" Scope in function. (Previous Code Style is
1. save plain Scope value in temp variable / 2. getValue From temp value
in function Scope, Now bind method is Inject Scope to Function)