정형진 강일구 2024-01-12T05:32:02Z 2024-01-12T05:32:02Z 1972-01-06 https://pubs.kist.re.kr/handle/201004/78598 적와용　점토를　이용하여　경량골재를　제조하는　방법 Patent 1972-01-06 1971-03-31 3662 71-460 KO 특허 한국과학기술연구원