1. Department of Textile Engineering , Politeknik STTT Bandung , Bandung , Indonesia
2. Department of Textile and Apparel Engineering , Politeknik STTT Bandung , Bandung , Indonesia
3. Department of Physics , Universitas Nusa Cendana , Kupang , Indonesia
4. Department of Physics , Universitas Gadjah Mada , Yogyakarta , Indonesia