Until a couple of weeks ago Koreans had never heard of Telegram, the super-secure Berlin-based messaging app that is now causing waves. Telegram is attracting droves of Korean users away, for increased security. In Korea, KakaoTalk is installed on 95% of smartphones, and Kakao messages surpassed SMS messages a few years back. Kakao is known for its ease of use and expressive emoticons. But now Kakao, which has established a near-monopoly in Korea, is facing a serious…