A jig having a guide block and a repositionable clamp for use with a saw for hand cutting tails and pins on the ends of boards to form a dovetail joint. The apparatus comprises a display screen, item selecting keys arranged around the display screen, and a communication device to connect with the server via the communication network. For this, a diode is provided to cause a loop current to flow back via the diode and the inductor so that the counter electromotive force is cancelled. The power supply unit can be used more broadly in different regions and provide more options when plugging to the power outlet. The guided waves are generated in the strip and coupled to the pipe or tube and propagate along the length of said pipe or tube. 1 to 1 \u03bcm accounts for 20% or more of the total pore volume, and the volume of the pores having a pore diameter of less than 0.