Provided are a data transmission apparatus and method which apply an appropriate coding rate according to significance of bits or bit groups included in uncompressed data and retransmit all or part of the data when a transmission error occurs in the data while the data is being transmitted over a wireless network. The mold is filled with a composite material and closed. RMA data for the returned product is uploaded to a database of a factory information system and is then verified for accuracy. The connecting element is disposed through the through hole for connecting the first conducting element and the second conducting element.