No, not north Korean but Chinese Navy ASW rockets:
Recently, a frigate group of the East China Sea Fleet of the PLA Navy conducted a close-to-actual-combat test on a number of tactics and fighting methods, in a bid to enhance the actual-combat capability of the troops. The picture taken on April 12 shows the No. 515 frigate of the group is launching bow rocket shells.
“No. 515 frigate” likely refers to the frigate Xiamen of the Jianghu-I-class. The weapon being fired is a Type 81 ASW rocket launcher with a max range of around 3,200m. Combat Fleets notes that most Jianghu-I’s carry only two of these weapons systems, but hull 515 (shown here) and 516 carry four mounts.