DDT와 유사한 화학 구조를 가진 유기염소계 살충제.
A synthetic organochlorine insecticide, chemically similar to DDT, used for pest control.
예문:
"The use of DDD was restricted due to its persistence in the environment."
"Researchers analyzed the soil samples for traces of DDD and other pesticides."
교환원의 도움 없이 사용자가 직접 다이얼을 돌려 연결하는 장거리 자동 전화 방식.
A telecommunication system that enables callers to dial long-distance numbers directly without an operator.
예문:
"DDD made it much faster and cheaper to call relatives in other states."
"The implementation of DDD required significant upgrades to the national switching network."