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https://libra.developmentseed.org/
https://landsatlook.usgs.gov/viewer.html
http://glcf.umd.edu/
https://worldview.earthdata.nasa.gov/
It's like I said maybe your best bet is to contact the universities in South Korea and find out. I am sure they have somebody there can lead you to find the information you need for North Korea datasets.
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In Earth Explorer, on the 'Data Sets' tab, expand the menu for 'Landsat Archive', then 'Collection 1 Level-1' to get Landsat 8 (expand 'Landsat Legacy' for older Landsat). You can then generate NDVI or whatever other analysis you wish in ArcGIS. Also available on Earth Explorer is 'Vegetation Monitoring' which has NDVI of MODIS and a few others. If you don't ...
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The Korean postal service offers downloads of the latest pre-reform postal codes here: https://www.epost.go.kr/search/zipcode/newAddressDown.jsp (page in Korean). The data takes the form of pipe-separated postal codes and addresses both romanized and in hangul. No latitude nor longitude.
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