The invention herein disclosed comprises the use of oxazolidines, nitroalcohols, nitrones, halonitroparaffins, oxazines, azaadamantanes, hexamethylenetetramine salts, nitroamines, imidazolidines, triazines, nitrooxazolidines, and imidazolidine-oxazolidine hybrids to serve as hardeners for curing phenolic resins. Each converter includes a PWM controller and switch circuit, an inductor, and an RC circuit. Therefore, a graphic object is reusable in graphic data processing, and accordingly, a time taken to process the graphic data is reducible and memory area may be saved. As the number of line cards expands, forwarding resources are expanded in at least rough proportion. Accordingly, with the simple structure in which the substitute enable signal is used, a proper enable clock signal can be generated and a scan test can be performed by reliably setting the sequential circuit to the enable state.