The look of Korean Philately (KP) has changed quite a bit in the last 70 years. There were many stages in the development of the covers of KP. The first KP was published by Harold D. Bearce, who was the first editor for the Korea Stamp Society (KSS), on October 1, 1951 with Albert L. Kemmesies as the first President of the society. It is believed that the first image of Issue 1 was created later, but represents very closely what the first issue actually looked like. (See article by Harold Bearce reproduced in this KP.)
In the beginning of the KSS and the KP, most members where from the USA and had been stationed in South Korea, either as military personnel or missionaries, so the focus of early articles were mostly about Korean Empire classic stamps and South Korean philately. Later as the society would become more international, with many members across the world, many articles on DPRK philately could be found in KP and this continues today with articles on all types of Korean philately.
Does anybody know when the US embargo on DPRK stamps began? Curious if in the early 1950s there was any kind of trade in DPRK stamps in the US. When I started collecting in the 1960s as a child, I never saw DPRK stamps and only rarely PRC stamps; when the embargo on China was lifted in the early 1970s it seemed obvious that stocks of stamps had been sitting around all that time. Did the early KSS try to bridge the information gap when DPRK listings were suppressed in Scott?
Good question about the official embargo. I have no idea, hope someone can answer. However, one thing relevant to the KSS is that the KSS used to have a sort of unofficial embargo on North Korean/DPRK stamps. That had to do with the (personal) experiences of many early KSS members, who had been either military personnel fighting during the Korean War or they had been for instance missionaries who had to flee when the North Korean army invaded in 1950. Sometime during the 1980s, when the first generation of members wasn’t so influential any longer, this informal embargo was lifted. Since then it even seems as if North Korean stamps have become more interesting to people than South Korean stamps. But that doesn’t answer your question of course.
The US embargo on DPRK stamps began in 1950 when North Korea invaded South Korea and the USA enacted the act of 1917, “Trading with the Enemy” against North Korea. I don’t think it was ever illegal to own North Korean stamps in the USA, but it was illegal to sell or import them for trade. Hal Klein, and early member of the KSS and also a long-time Board member, and serious collector of North Korean stamps, explains briefly on page 19 of the lastest KP (4th quarter, 2021) how he was able to collect North Korean stamps. So I believe it is “officially” still not legal to sell DPRK stamps in the USA as PayPal, for example, will not allow the listing of “North Korea”, but dealers do list them under the the heading of “Korea”. You can understand a bit of the reluctance of Americans to collect DPRK as they have put out propaganda stamps of the North Korean military killing USA troops and even killing USA Presidents.