1. A method of providing a partially-isolated execution environment for multiple applications in a digital information apparatus comprising a virtual machine and middleware, the method comprising: initializing an application manager by executing the virtual machine, and loading and initializing a main class of the middleware; executing an action for each application through a method of the application manager while executing a main method of the main class of the middleware; and finalizing all threads and ending a process during execution in the virtual machine, wherein the executing of the action comprises executing the action by generating a thread structure on a per-application basis and associating the thread structure with an object of a representative class that represents a system execution environment, the object of the representative class being generated on a per-application basis, and wherein a finalizer thread, of the generated thread structure, is registered on a per-application basis.