Vungle, the way developers put video ads in their apps, has opened a South Korean office to accelerate growth and global expansion for the country’s startups through high performance in-app advertising. Vungle Korea is led by industry heavyweight, Hong Kim, former CEO of Groupon Korea. Kim brings a solid background in startups and finance, along with a passion for growing companies globally to his new role with Vungle. “South Korea’s startups have…