By Ju-min Park and Minwoo Park YEONPYEONG ISLAND, South Korea (Reuters) – As Kim Jeoung-hee huddled in a bomb shelter on South Korea’s Yeonpyeong Island, scared and confused with around 250 other people, memories flooded back of the day in 2010 when North Korean troops shelled near their homes. Authorities told them to take shelter on Friday as North-South tensions spiked again. This time no-one aimed any shells at the small patch of land just on the southern side of the two Koreas’ disputed maritime border. But the alarm was a reminder of how vulnerable Yeonpyeong remains more than 13 years a…