can't set and get selected value when binding with ngModel

[sithwin]

I am trying to use polymer paper-dropdown-menu and paper-listbox. Now I am having problem in binding.

Here is dropdown list:
<select name="singleSelect" [ngModel]="(person | async).department"> <option *ngFor="let x of departments">{{x.name}}</option> </select>

I converted into paper-listbox or paper-dropdown-menu
<paper-listbox #department ngDefaultControl name="department" [ngModel]="(person | async).department" label="department" > <paper-item *ngFor="let x of departments"> {{ x.name }} </paper-item> </paper-listbox>

departments = [{name: 'HR'}, {name: 'IT'}, {name: 'Admin'}, {name: 'Management'}];

I couldn't get and set selected value.

Please help!