After discussing the matter with her parents and language tutor, Rhiannon decided to undergo an operation to correct the condition, despite the fact it has never caused her any problems in speaking English.
She underwent a lingual frenectomy, which involves making an incision in the flap of skin. As a result, Rhiannon's tongue is now about 1cm longer, and she can say words that were impossible before.
Rhiannon, of Beeston, Nottingham, said: 'I'd been learning Korean for about two years, and my speaking level is now high, but I was really struggling with particular sounds.
'It became apparent after a little while that I was having trouble with the Korean letter 'L', which is very frequent and comes from a slightly higher place in the mouth than the English 'L', and that my tongue was too short.
'My pronunciation was very 'foreign', but now I can speak with a native Korean accent. The surgical procedure was my only option. It's not like you can stretch your tongue otherwise. I just decided enough was enough.
'For me it was an important thing, because I'm a bit of a perfectionist, and if I can't do it perfectly, it really irritates me.
Rhiannon is currently awaiting her A-level results, and hoping to study Korean Studies and Business Management at the University of Sheffield.
The four-year course includes a year at Yonsei University in the South Korean capital, Seoul.
She added: 'I think this will show real dedication. It will prove I'm not just going to drop out after a year.
'In Korea they like good students, and I think having my tongue lengthened will be a real help with the course, especially during my year in Seoul.
'Native English speakers can earn quite a lot of money in Korea, so that's another option.'
Rhiannon became interested in the Asian nation's culture through a friend at school.
The teenager said: 'She was into Korean pop and television programmes, which I would listen to and watch at her house.
'Most of my free time was soon taken up with Korean things. Now I visit a Korean Church in Nottingham, where I do bible readings in Korean, and can't wait to visit the country itself.
Rhiannon's mother, Fiona Brooksbank-Jones, 56, said she supported her daughter in undergoing the procedure.
She added: 'As her parents, we welcome her interest in other parts of the world, and are very proud of her.
'I've heard of people having the condition corrected as babies, but never later in life. But we looked into it, and have backed her all the way.
'When she sets her mind to something, she usually goes for it wholeheartedly, and this was no different.'
來源：中國日報 編輯：許銀娟