The purpose of this paper is to show that we are now able to apply standard portfolio optimization methods to the management of small and medium scale fund, where transaction cost and minimal transaction unit constraints are not negligible. Unit transaction cost is usually larger when the amount of investment is smaller. Also, rounding of portfolio to the nearest integer multiple of minimal transaction unit will have non negligible effect on the risk-return structure of the portfolio. We will show that the use of mean-absolute deviation model enables one to handle concave transaction cost and minimal transaction unit constraints in an efficient manner using branch and bound algorithm. Also, we will show that the minimal transaction cost rebalancing problem can be solved by using the same algorithm.