For pet owners, we'd like to introduce some places :)

Vet Clinics
KN Pet Hospital  http://www.animalrescuekorea.org/vet-clinic/1176
TeunTeun Pet Hospital
https://www.google.co.kr/maps/place/%EA%B2%BD%EA%B8%B0%EB%8F%84+%ED%8F%89%ED%83%9D%EC%8B%9C+%ED%8F%89%EB%82%A8%EB%A1%9C+655/

Pet Grooming
Humphreys Pet Grooming http://www.usaghumphreyspetgrooming.com/
Dog Town Club & Show Grooming https://www.facebook.com/HumphreysDogtownClubShowgrooming/

Supply Shop & Dog cafe
You can get most of the supplies at vet clinics or on-post.
But If you are looking for cute supplies, there's one good place.
It's 'The Dog'. The owner owns a supply shop at the first floor and a dog cafe at the second floor.
You can bring your dog with you. At cafe, there's no admission fee but you order 1 drink per person.
https://www.facebook.com/pages/The-Dog/816198588390293
https://anjeongrireviews.wordpress.com/tag/dog-cafe/