From my favourite Korean cooking site - jjajiangmyun recipe
And from another site, it confirms my suspicions that confirms that it's similar to the chinese jia jiang mian but the taste is different http://www.sunnysideuprecipes.com/2010/02/ja-jang-myun.html
So it looks like I can't use the soya bean paste but would have to get real Korean black bean paste. Yes, one day I'll go to the Asian grocer and get the ingredients including the special jiajiangmyun!