This paper analyzes anti-competitive behaviors and provides a direction of their regulation in the restructured Korean power market. Using the System- Operating-Model, three separate strategic behaviors are simulated. The policy implications are derived as follows. (1) The nuclear company will earn positive profits from its strategic idling behavior. Must-run contracts should be applied to control the behavior. Moreover, the division of the company into two separate entities could be considered. (2) If some of coal-fired generators intentionally decrease the output of power, the market-clearing price will rise dramatically. A sophisticated set of market monitoring indicators and techniques should be developed to operate the market properly. (3) Had some of the pumped storage generators been reserved over peak time, peak-shaving function would have been considerably weakened. Various formats of the (implicit) collusion should be carefully examined to prevent the generators from exercising market power over peak periods.