Based on the level of respect or formality, you can say "You are a unlucky person" in Korean in 3 ways:

• Informal: neo-neun bulhaeng-han saram-iya (너는 불행한 사람이야)
• Formal: dangsin-eun bulhaeng-han saram-iyeyo (당신은 불행한 사람이예요), dangsin-eun bulhaeng-han saram-ipnida (당신은 불행한사람입니다)
• Very Formal: dangsin-ggeseo-neun bulhaeng-han saram-isipnida (당신께서는 불행한 사람이십니다 )

- you (subjective): ne-ga (네가), ni-ga (니가), neo-neun (너는), dangsin-eun (당신은), dansin-ggeseo-neun (당신께서는)
- unlucky person: bulhaeng-han saram (불행한 사람)
- person: a (아), saram (사람)

Please refer to How to pronounce Korean Alphabet for the English pronunciation in this answer.