Researchers at the Semiconductor Photonics Lab., Hanyang University, Ansan, Korea, led by Jong-In Shim, study, evaluate, and improve the performance and reliability of light-emitting diodes (LEDs). The lab has various unique simulation and characterization techniques, including an efficient in-house simulation tool for three-dimensional current distribution analysis in the LED device and a system that extracts the internal quantum efficiency from the electroluminescence measurement. On p. 2133ff. Dongpyo Han et al. demonstrate that the current crowding in the LED device causes nonuniform light emission and local heat generation, eventually affecting the LED performance badly. The large figure shows the simulated current distribution in an LED device, obtained by the in-house simulation tool. The second figure, placed on the upper right, is the light distribution image of the same device, taken by a charge-coupled-device (CCD) camera. The last figure on the lower right is the temperature distribution image of the same device taken by an infrared camera.