The rest of the paper is organized as follows. Firstly, a brief introduction of Cpk
along with the proposed plan is given in Section 2. The formulations of the proposed plans under symmetric and asymmetric cases are discussed in Section 3. The analysis and discussions of the performance of the proposed plan are given in Section 4. The advantages of the proposed plan over the single plan are also discussed here. An example is presented in Section 5. Finally, some concluding remarks are made in the last section.