1. 1) W.L.Roberts: Trans. ASME, 88 (1966), 103.
2. 2) T.Mase, T.Kono and H.Yamamoto: Proc. 28th Japanese Joint Conf. Techol. Plast., (1977), 114.
3. 3) T.Mase, T.Kono and H.Yamamoto: Tetsu-to-Hagané, 64 (1978), S704.
4. 4) K.Nakajima, Y.Shibata and Y.Uebori: Proc. 1979 Japanese Spring Conf. Technol. Plast., (1979), 379.
5. 5) M.Shirata and K.Sakai: J. Jpn. Soc. Lubr. Eng., 27 (1982), 594.