Neb. Rev. Stat. § 21-1983

(a) A director may at any time waive any notice required by the Nebraska Nonprofit Corporation Act, the articles, or bylaws. Except as provided in subsection (b) of this section, the waiver must be in writing, signed by the director entitled to the notice, and filed with the minutes or the corporate records. (b) A director's attendance at or participation in a meeting waives any required notice of the meeting unless the director, upon arriving at the meeting or prior to the vote on a matter not noticed in conformity with the act, the articles, or bylaws, objects to lack of notice and does not thereafter vote for or assent to the objected to action.