function unlockToken() public onlyOwner {
        require(ownerLockedBalance > 0);
        require(block.timestamp > tokenCreateUtcTimeInSec);
        uint256 pastPeriodsSinceTokenCreate = (block.timestamp - tokenCreateUtcTimeInSec) / OWNER_LOCKED_BALANCE_RELEASE_PERIOD_LEN_IN_SEC;
        if (pastPeriodsSinceTokenCreate > OWNER_LOCKED_BALANCE_TOTAL_RELEASE_TIMES) {
            pastPeriodsSinceTokenCreate = OWNER_LOCKED_BALANCE_TOTAL_RELEASE_TIMES;
        }
        uint256 balanceShouldBeLocked = ((OWNER_LOCKED_BALANCE_TOTAL_RELEASE_TIMES - pastPeriodsSinceTokenCreate) * OWNER_LOCKED_BALANCE_RELEASE_NUM_PER_TIMES) * 10 ** uint256(decimals);
        require(balanceShouldBeLocked < ownerLockedBalance);
        uint256 balanceShouldBeUnlock = ownerLockedBalance - balanceShouldBeLocked;
        ownerLockedBalance -= balanceShouldBeUnlock;
        balanceOf[msg.sender] += balanceShouldBeUnlock;
    }