What does SGK stand for?

Hsinkong - Republic of China - Also, HSI - Seismograph station code, US Geological Survey (SEIS)

Knoxville, TN - Location identifier - FAA (FAAL)

Schawk, Inc. - Formerly, Filtertek Inc. - NYSE symbol (SAG)

Schawk Inc.`A' - NYSE symbol

Schweizerische Geologische Kommission - Swiss Geological Commission (GIS)

Skyward Aviation Ltd. - Canada - ICAO designator (FAAC)