The explanation I had given below for 방활사 was completely wrong. The same reader who first asked me about the word has sent me another email saying that he found that the Chinese characters for 방활사 were 防滑沙, which literally mean "Prevent (防) Slipperiness (滑) Sand (沙)." In other words, it is sand that is spread on slippery roads in the winter to give vehicles traction.
However, the word 방활사 (防滑沙) is a non-standard word and does not appear in any dictionary that I have. The word has confused not only me, but others, as well. In a Korean article HERE, the word was used as an example of how Korean government officials and others are creating new words from Chinese characters that that few can figure out without also seeing the Chinese characters. The article asks what good are government information and warning signs when people cannot understand what they mean.
By the way, Korean government officials are not the only ones who invent language. When I was in the US navy, I was exposed to a bewildering set of acronyms and initialisms that seemed to grow day by day. The US navy loved acronyms, but I hated them and finally gave up trying to learn them all. However, many of my fellow sailors loved using them because, I suspect, it showed that they had special knowledge that many others did not have. Maybe that is why Korean officials also like using them.
I agree with the Korean article I linked to above: What good is a public sign if the general public cannot understand what it says?
Below is my original post.
A reader sent me the following photos of what looks like a dog house and asked me what they were. He said he saw them spaced at different intervals along a road in Gangwon Province.
The sign on the second photo reads 방활사, which is meant to mean "sand for preventing fires," so the structures are for storing sand to be used for smothering fires that may occur along the highway. The ㄹ at the end of 화 is a future tense marker that can be translated here as "for."
"Fire prevention sand" is written as 방화사, so 방활사 is a misspelling. If they had intended it to be read as the phrase, "Sand for Preventing Fires," then they should have written it as "방화할 사" or "방화할 모래." It looks like Inje County (인제군) officials need to not only work on their spelling, but also need to refill their sandboxes.
By the way, that is a pretty nice road.