Standard Korean has an interrogative inflection (as opposed to declarative, imperative and propositive moods), as part of the property known as the "pragmatic mood". It is characterised by -ㅂ니까 -mnikka for vowel stems or -습니까 -seumnikka for consonant stems in the formal polite level (as in 합니까 hamnikka and 있습니까 issseumnikka) and -느냐 -neunya for the formal plain level (하느냐 haneunya / 있느냐 issneunya). Adjectives (i.e. descriptive verbs) have a different inflection for the formal plain level: -냐 -nya for vowel stems and -으냐 -eunya for consonant stems. For all forms, this may be abbreviated to -니 -ni in speech.
There is generally no formal inflection distinction in the intimate (informal plain) [although many other interrogative forms are used, e.g. -지 -ji], the general polite (informal polite), the authoritative (semi-formal polite) and familiar (semi-formal, semi-polite).
Interestingly enough, the Gyeongsang dialect group of Korean (including Busan), in its informal plain layer, distinguishes between yes-no questions and wh-questions by inflection, with an -아 -a or -나 -na for yes-no questions and -오 -o or -노 -no for wh-questions.