On the Study of Reaction Yields of $${{}^{\mathbf{13}}}$$C($${{\gamma}},\boldsymbol{p}$$)$${}^{\mathbf{12}}$$B, $${{}^{\mathbf{14}}}$$N($${{\gamma}},\boldsymbol{2p}$$)$${}^{\mathbf{12}}$$B, and$${{}^{\mathbf{14}}}$$N($${{\gamma}},\boldsymbol{2n}$$)$${}^{\mathbf{12}}$$N through Measurements of ($${}^{\mathbf{12}}$$B, $${}^{\mathbf{12}}$$N) Activities with $${\Delta}\boldsymbol{E}$$-Detector Telescopes between Electron Accelerator Pulses