Here are some more myths & legends about Korea's Mountain-spirits that I have collected and written up, in preparation for the second edition.  They are quite revealing about various facets of San-shin's personality and use by Koreans.   These tales appeared in the first two Sections of Chapter II.    Enjoy reading:
The softer, virtuous-human-assisting aspect is represented in the legend that I found carved on a Hyoja-biseok [filial-son stone-monument] along a highway in remote Pyeong-chang County on the western side of Gari-wang-san [King-of-Universe Mountain, 1560m in central Gangwon Province].   A good mother fell deathly ill some three hundred years ago, and her family was told that only a special type of fish from the East Coast could cure her.  There was not nearly enough time for anyone to make the dangerous round-trip journey through the wild Tae-baek-san-maek [Grand-white Mountain-range, Korea's eastern spine] and no horse available, but the filial eldest son set off on foot anyway, determined to get that fish. 

Soon, at a high pass in the wilderness he confronted a large tiger, and was sure he would be eaten.  But the tiger just knelt and let him climb on its back, then took off galloping towards the east.  The son quickly reached the coast on his amazing mount, bought the medicinal fish, got back on the tiger and rode on it all the way back to near Pyeong-chang Town.  He dismounted at the edge of the forest near his house, and thanked the tiger profusely.  It revealed itself to be the Gari-wang-san-shin and then disappeared.  The son went home, cooked the fish and fed it to his mother in front of their astounded relatives. Of course, she fully recovered, and a lavish ceremony thanking Gari-wang-san-shin was held.
an excellent San-shin & Deok-seong pair from Yak-su-sa [Medicinal-Water Temple] in Hong-cheon County.
That Hyoja-biseok Shrine near Pyeong-chang Town, and the crude San-shin painting and signboard from Daedeok-sa [Great Virtue Temple] -- a small remote nun's temple on the western slopes of Gari-wang-san in Gangwon Province.  Note that San-shin is depicted sitting in a Zen-style "full-lotus" cross-legged posture; this is quite rare.
continued...
The character of San-shin is best illustrated by the myths and legends told about them.  One myth shows the stricter, taboo-enforcing aspect:  long ago, a woman called 'Yeonjin' lived together with her husband 'Hoya' in Daeseong Gyegok [Great Sage Scenic-valley] of Jiri-san.  They couple did not have any children, although they wanted them.  One day a local bear visited Yeonjin and told her the location of a mysterious spring called the Eum-yang-su-teo [Yin-Yang water-source] that would be enable her to have children.  Yeonjin was so happy that she set off at once without consulting her husband, and drank a lot from the spring.

However, a tiger who felt rivalry with the bear overheard the conversation and reported it to the Jiri-san-shin.  The goddess was enraged, and imprisoned the bear in a cave for divulging the secret to human beings, while promoting the tiger to "King of Animals".  She also punished Yeonjin harshly for stealing the holy Eum-yang-su, commanding her to grow Royal Azalea flowers on the rocky plateau Seseok-pyeong-jeon for the rest of her life.  They say that the unfortunate-destiny Yeonjin sprinkled the blood from her worn fingers on the flowers, giving them their deep-red beauty, and to this day they bloom and fade with Yeonjin's piteous soul embedded in them.  Also, it is said that at the end of her days Yeonjin deeply repented her sins and knelt up on Chottae-bong in front of lit candles facing the great Cheon-hwang-bong [Heavenly-King Peak, 1915m, the highest peak in mainland South Korea], praying on for mercy from its Yeo-san-shin [Mountain-goddess] until she finally turned into a bawi [outstanding boulder or crag].