Investors are shunning Doosan Group, the nation’s 12th largest conglomerate by assets, as growth at the industrial giant appears to be stalling.Shares of the group’s two key units ― Doosan Heavy Industries & Construction and Doosan Infracore ― each hit a 52-week low this month, falling from their respective annual highs of 46 percent and 34 percent.“The group faces problems as its key affiliates seem to have no way out of their prolonged business slumps, at least for the time being,’’ a senior s