According to Wikipedia, siling haba is 50,000 Scoville Heat Units (SHU) while Korean chili peppers are 1,500 SHU unless it's specifically a Chyeongyang chili pepper which is 10,000 SHU. I don't know if siling haba is quite that spicy since Serrano is supposedly 25,000-50,000 and I thought that was spicier than siling haba, so I think if it's a Chyeongyang chili pepper, you should go use that. 10,000 is only slightly spicier than a jalapeño (4,000-8,500 SHU).