In order to minimize the delay of the video images viewed by a network conference attendee, an intelligent buffering process selectively discards video frames from at least one point, and in an embodiment, many network points, such as at \u201cin\u201d andor \u201cout\u201d buffers of clients, servers, routers, etc. The phase difference between the first and second signal is determined as a first group phase delay. The base plate is secured to the jamb by passing screws through appropriate openings located on the base plate while the strike plate is held secure when it is slid to its desired position by passing one or more set screws through screw openings located on the strike plate, the set screws engaging the door jamb. The total heat exchange wheel faces to the first and second airflows provided by the air-providing member, and is capable of rotating through the first and second air passages for conducting a total heat exchange between the first and second airflows. Since no fine gap is created in the electrolyte injection hole, the electrolyte is prevented from flowing into the welded portion due to a capillary phenomenon and no pin hole caused by the electrolyte is formed in the welded portion.