In South Korea, KBS is the only main broadcaster which having shortwave radio transmitters, meanwhile Echo of Hope, Voice of The People and Voice of Freedom are South Korea clandestine radio stations to target North Korea.
KBS (Korean Broadcasting System) is a public broadcaster, owned by South Korea government.
EBS (Education Broadcasting System) is an education TV/radio broadcaster, considered public owned. Formerly was launched as KBS 3 for TV station, and EBS demerged from KBS.
CBS (Christian Broadcasting System) is a religious broadcaster for Christians in South Korea.
MBC (Munhwa Broadcasting Corporation), a well-known commercial broadcaster in South Korea.
MBC, CBS, and EBS never have shortwave radio broadcast at the time being. We know that North Korea only jams KBS channels in the communist country to prevent its people from watching and listening to South Korea government propaganda. In North Korea, MBC, CBS and EBS are not jammed as they're commercial, religious and education broadcasters respectively, however these radio stations on FM and MW are only available in bordering region such as Kaesong, Haeju and areas nearby 38th Parallel (aka DMZ).
I'm thinking if MBC, CBS, and EBS launch shortwave transmitters like KBS, despite South Korean people don't really listen to shortwave radio stations as they listen to FM, MW, and DMB.
Shortwave transmitters can even travel further than mediumwave actually due to its propagation. If South Korea MBC, CBS and EBS use directional shortwave transmitting antenna to beam north direction, North Korea can receive even clearer.
If MBC, CBS, and EBS have shortwave broadcasts to target North Korea and Koreans in China, there are advantages, but limitations must be considered.
==Advantages==
1. For MBC, as it provides more music and entertainment, North Koreans can tune to MBC Radio via shortwave frequencies, alternative to KCBS Pyongyang, Pyongyang Broadcasting Station, Echo of Unification and Pyongyang FM.
2. For EBS, North Koreans can listen to South Korea education radio station in the country on shortwave frequencies to learn many languages, culture and liberal arts. In South Korea, unlike KBS and MBC which also broadcast on MW band, EBS only broadcasts on FM frequencies.
3. For CBS, the broadcaster can spread Christianity believes to North Korea natives via shortwave transmission in Korean language, just like USA based FEBC, KTWR, Adventist World Radio broadcast on shortwave frequencies to spread Christianity believes to the whole world in multiple languages.
4. CBS, EBS and MBC can gain more listeners from North Korea by reaching more coverage into Deep Korea.
5. Korea Peninsular can receive CBS, EBS and MBC radio via shortwave frequencies, despite they can't expand on FM and MW bands because Korea is divided into two (North and South).
==Limitations==
1. As North Korea is a communist nation which is fully isolated country, not like China where is already opened country ("semi-communism", but more to socialism), North Korea government can jam MBC, CBS and EBS because the country already jam all Korean languages foreign shortwave broadcasts (including BBC World Service, China Radio International, Adventist World Radio, NHK World Radio, KTWR Guam, Radio Free Asia and Voice of America).
2. For CBS, because North Korea does not allow its people to believe in any religion regardless Buddhism, Islam, Christian, Taoism, Hindu, Roman-Catholic etc, people there only worship Kim's Supreme Leaders as their religion believes. Hence, I also think that North Korea government jams CBS, even the government also jams foreign religious shortwave radio stations in North Korea, especially Korean language services.
3. To launch shortwave broadcasts, it is not easy and it is expensive to do so because it needs much money to have shortwave transmitters. Transmission fees, transmission equipment maintenance fees and hardware purchasing costs must be considered.
4. Listeners and commercial factors. There is no any database that how many North Koreans will listen to MBC, CBS and EBS on shortwave radio frequencies, so the advertising revenue to the broadcasters are unknown because their advertisers market is only in South Korea, this factor applies to MBC mostly because MBC is commercial broadcaster in South Korea, and it is not government-funded TV and radio station.
Talk about Korea unification, it is not easy to do so at the time being because two Koreas are still in tension, despite relationship is inconsistently improved. If North Korea communist government is dissolved like East Germany and Soviet Union, and unified into South Korea, I may believe North Korea KCTV and KCBS Pyongyang could be replaced by KBS, then I may expect MBC, CBS and EBS expand their broadcast coverage to North Korea. However, the unification is not simple at all, politics are always dirty.
==Transmitter sites==
If MBC, EBS and CBS have shortwave transmitters to target North Korea, it is sufficient to operate at 100kW transmitter power. 100kW transmitter power is enough to cover North Korea, but for transmitter site, they can select either Hwaseong or Gimje. For the shortwave transmitter sites in South Korea, I mostly see those North Korea targeted radio stations are transmitted in Hwaseong and Goyang City within Gyeonggi Province, rather than Gimje (KBS World Radio site).
KBS Hanminjok-1 shortwave transmitter site is located in Hwaseong.
Gimje is located in North Jeolla Province, it is not really possible to cover all territories in North Korea, compare to Hawseong and Goyang, also Seoul. Gimje shortwave transmitter tower is actually for international broadcast to target most of the world. In fact, if MBC, EBS, and CBS want to use Gimje shortwave radio tower to target North Korea, they should use directional antenna and high power transmitter as 300kW, therefore they can reach all territories in North Korea.
==Frequencies==
As shortwave frequency band range is wide, and many international broadcasters occupied many frequencies, regardless target in selected region or whole world, I'm not able and having zero idea on it.
==Proposed transmission data for MBC, EBS, CBS shortwave broadcast to target North Korea==
1. Hwaseong, Gyeonggi Province
* Power: 50kW or 100kW
* Antenna direction: Non-directional
* Note: Currently used by existing radio stations such as Echo of Hope, KBS Hanminjok Bangsong-1
2. Seoul
* Power: 20kW
* Antenna direction: Non-directional
* Note: Currently used by Echo of Hope only
3. Goyang City, Gyeonggi Province
* Power: 100kW
* Antenna direction: Non-directional
* Existing stations: Voice of The People SW 3480kHz, 3910kHz, 3930kHz, 4450kHz, 6520kHz and 6600kHz.
4. Gimje, North Jeolla Province
* Power: 300kW
* Antenna direction: Between 280 DEG and 80DEG
* Existing station: KBS World Radio
==Conclusion of proposed transmitter site for MBC, EBS, and CBS shortwave broadcast for North Korea==
Hwaseong is the best transmitter site for MBC, EBS and CBS on shortwave radio transmission because there are at least two broadcasters operate shortwave transmission there such as KBS Hanminjok Bangsong-1 and Echo of Hope.