New Associated Curves k-Principle Direction Curves and N_k Slant Helix
  The Frenet frame is generally known an orthonormal vector frame for curves. But, it does not always meet the needs of curve characterizations. In this study, with the help of associated curves of any spatial curve we obtained a new orthonormal frame which has the property that the second vector makes a constant angle with a fixed direction for the spatial curve. Then, the curve is named as the N_k slant helix and the special conditions are obtained effectively. 
Cagla Ramis, Beyhan Uzunoglu and Yusuf Yayli
math.DG