May. 1984   : Oh Sung Trading Co., Ltd. Established. Jun. 1989    : Conclude Exclusive Distributor and Agentship with                    Kett Electric Laboratory in Japan. Feb. 1992    : Korea Kett Sales Co. Established. Feb. 1992    : Conclude Exclusive Distributor and Agentship                        with Zeltex Inc. in U.S.A. Aug. 1994    : Korea Kett Engineering Co., Ltd. Established. May. 2001    : Continue..