NSO

https://www.youtube.com/watch?v=HvC8xIpEwYY

https://www.youtube.com/watch?v=t9WYalN6zNw

새 모양의 NSO

https://www.youtube.com/watch?v=BJrW5DvwlJ0

NSO의 종류

https://www.youtube.com/watch?v=3ePsTWiDoMo

물방울 같은 모양 dpa

https://www.youtube.com/watch?v=Tkhof1Tf65Q

NSO 새벽2시30분