KDSM requirements are in the updated AR 600-2-88, Military Awards in paragraph 2-22 (see excerpt below).
A. Authorization. The KDSM was authorized by Section 543, National Defense Authorization Act, 2003, PL 107 – 314. It is authorized for award to Servicemembers of the Armed Forces of the United States who have served on active duty in support of the defense of the Republic of Korea. The AOE and period of eligibility are as follows:
B. Criteria. Servicemembers must have been assigned, attached, or mobilized to units operating in the AOE for 30 consecutive or for 60 nonconsecutive days, or meet the following criteria:
C. Special provisions. Servicemembers qualified for the AFEM by reasons of service between 1 October 1966 and 30 June 1974, in an area for which the KDSM was authorized subsequently, are eligible for both the AFEM and the KDSM. Award of the KDSM for this time period is a one-time exception to policy to comply with section 543, National Defense Authorization Act, 2003, PL 107 – 314.
To apply for your medal and correct your records to reflect award of such medal and have left the service before 2002, fill out the SF 180 and send it to:
National Personnel Records Center (NPRC)
Military Personnel Records
1 Archives Drive
St. Louis, MO 63138-1002
NPRC will add the Korea Defense Service Medal to the records by correcting the DD214 to include it and will issue a DD FORM 215 (CORRECTION TO DD FORM 214, CERTIFICATE OF RELEASE OR DISCHARGE FROM ACTIVE DUTY). If you have in your possession a copy of current military records that show service that entitles you and send them along with it to possibly expedite the process. (DO NOT SEND ORIGINALS OR THE ONLY COPY YOU HAVE)
For convenience a SF 180 for is included on our website. Standard-Form-180