The employment rate has increased by somewhat unnoticeable amount over the past 10 years [1]. The increased housing supply is mostly due to cost factors (tax breaks from the previous administrations, low interest rate) and the demand due to decline of small cities (demand gets concentrated around Seoul, the capital city; people buy houses around Seoul while living far away in another place on rent). As for the office/factory/commercial space, there has been a sharp increase in supply, and the vacancy rate (spaces that cannot find tenants) is 10-20% in major cities. Folks still buy buildings with a yield of 2.5-4% because the interest rate is so low. I am currently based in Cambridge, Boston. There are empty stores that have been looking for tenants for more than a year.
[1]: http://www.index.go.kr/unify/idx-info.do?idxCd=4013