Since 1986, Doohyeon has been a leading manufacturer of Diamond Core Drill in Korea.We are proud of our products which have been manufactured with our original idea, high technology and many experiences in machining and construction works.In other to meet needs of customers, we perform tightly quality control in all processes and sticky test before ex-factory.Also we are doing with our best to provide customers with most competitive products and technical information available under motive that our success is measured by the succes of our customers.Thank you very much for your time and concern.