Use of Similarity of Triangular Fuzzy Numbers and a Derivation Calculation Formula in Assessment of Mortise-Tenon Joints Applied in the Joinery Category of Regional Taiwan Skills Competitions

This study is intended to assess the types of joints applied in the Joinery Category of the Regional Taiwan Skills Competitions (hereafter referred to as the Regional Competitions, including Northern Taiwan, Central Taiwan and Southern Taiwan). The authors use a self-developed derivation calculation formula ( ∑ i = 1 n w × h i ) to examine the differences in the types of joints applied. Then a regression equation is adopted to estimate the distribution of weight values of the joint types to calculate the assessed values of the joint types likely to be used in the Regional Competitions of the 51st Taiwan Skills Competition. Subsequently, the similarity of the fuzzy number is employed to understand the tendency in the development of joint types from the 36th Regional Competition to the 50th Regional Competition. The outcome shows that 19 types of joints were applied and the assessed value of 2.3 of open bevel mortise-tenon joints was the highest, followed by the 2 of bevel inclined mortise-tenon joints and the 0.73 of sloped haunch mortise-tenon joints. Meanwhile, the application of similarity of triangular fuzzy numbers to examine the 19 types of mortise-tenon joints indicates that the area of the affiliation map of open bevel mortise-tenon joints is the largest. Compared to the other 18 types of mortise-tenon joints, the assessed value of level of similarity is the lowest. In other words, the assessed values acquired by using the similarity of triangular fuzzy numbers and by using the derivation calculation formula have the same tendency. Hence, it is suggested that when trainers/instructors determine training strategies, they should adopt open bevel mortise-tenon joints, bevel inclined mortise-tenon joints and sloped haunch mortise-tenon joints to be the assessment standards. At the same time, they can also use the affiliation map of similarity of triangular fuzzy numbers to evaluate the differences between various types of mortise-tenon joints to understand the tendency of joint type development. Thus, the teaching quality of trainers/instructors and the learning results of contestants can both be upgraded. Systematic approaches also have to be consolidated to strengthen the ability to assess vocational education and training (VET) in order to improve the learning effects and technical capacity of Joinery category contestants. It is hoped that the derivation calculation formula can be applied to evaluate the training of Joinery category contestants in regional competitions to improve the quality of VET.