Tense and Aspect: Is Korean -았/었 the Same as Japanese -た?
Japanese -た also marks completion, discovery and confirmation
Korean and Japanese past tense forms look similar but have subtly different usages.
Common: Basic Past Expression
Korean: 먹었다 / Japanese: 食べた
Korean: 갔다 / Japanese: 行った
These correspond 1:1 perfectly.
Difference: Extended Uses of Japanese -た
Japanese -た has functions beyond past tense.
Discovery: "あ、ここにあった！" — In Korean, present tense "있다" is more natural
Confirmation: "明日は日曜日だった" (Tomorrow was Sunday, right?) — Not past, but confirmation/recall
Command: "さっさと帰った帰った！" (Go home already!) — Korean doesn't use past tense as command
Korean -겠- vs Japanese Conjecture
Korean "-겠-" (conjecture/volition) doesn't have a single Japanese equivalent. It splits into だろう, でしょう, つもり depending on context.
Key Points
Basic past tense (-았/었 ↔ -た) maps 1:1
Japanese -た has non-past uses: discovery, confirmation, command
Korean -겠- splits into だろう/つもり etc. in Japanese