The trolleybus in Kubong, mentioned in Trolleybus Magazine #246 as Ryongdae, is proven to have existed by this article. The KCNA release is dated 1993/6/10, stating that a trolleybus has started operating in Kubong-rodongjagu.

The article describes the trolleybus system as running "24/7 to ensure miner's convenience", over a distance of 10-ri (3.9 km) from the "2nd pit" to miner's homes with 4 stops.

On satellite, a trolleybus is seen running in 2002 and the southern loop is still visible in the 2005 imagery, afterwards which it has been dismantled and turned into housing.

Here is where the Trolleybus Magazine #246 likely made its mistake of stating a trolleybus had likely opened in Songrim - this article combines the news of the Ryongdae Mine trolleybus with that of a commuter train for the Hwanghae Iron and Steel Plant.

Скорее всего южное кольцо было расположено по координатам 39°28'10.96"N 126°10'19.15"E. На снимках 2002 и 2005 года можно заметить нечто похожее на опоры поддержки КС. На снимках 2002 года отчетливо видны опоры натяжения кривых и одну опору компенсации посередине. По координатам 39°28'34.00"N 126°09'59.15"E можно заметить движущийся по линии единственный троллейбус. На снимках 2005 по всей улице, где в 2002 году замечен троллейбус, видны опоры поддержки контактной сети. Осталось лишь найти второе кольцо. Те, у кого будет больше информации о троллейбусных системах Кубонгу, Унхына, Сунчхона и Рёндынгу, пожалуйста, делитесь этой информацией в комментариях к фотографиям из галерей этих городов.

There is a possibility that the trolleybus terminates within the mine tunnels, as the stated length (3.9km) does not fit within the mining village to the mine.
Also, past the tunnel entrance, the roads are in much worse condition, so I don't think the trolleybus ran there.

The Ryongdung south loop is at 39°49'43.12"N, 126° 4'59.15"E. North loop is probably 39°51'4.36"N, 126° 3'56.89"E

Цитата (jiachen, 09.10.2023):
> The Ryongdung south loop is at 39°49'43.12"N, 126° 4'59.15"E. North loop is probably 39°51'4.36"N, 126° 3'56.89"E

I think that you indicated the rings correctly, because the platforms have the shape of an ideal turning trolleybus ring. Most likely, after the dismantling of the trolleybus contact network, a small residential building was built on the territory of the northern ring. This house can be seen on 2016+ satellite frames.