Improvement of input power factor in AC choppers using asymmetrical PWM technique. - Do-Hyun Jang; Gyu-Ha Choe (IEEE Trans. Ind. Electron., 1995)

Step-up/down AC voltage regulator using transformer with tap changer and PWM AC chopper. - Do-Hyun Jang; Gyu-Ha Choe (IEEE Trans. Ind. Electron., 1998)

A Multiobjective Parametric Optimization for Passenger-Car Steering Actuator. - Hae-Ryong Choi; Gyu-Ha Choe (IEEE Trans. Ind. Electron., 2010)