hand 1: villain is 21/3.6/0.5 around 28 hands. whats the optimal play on A turn when i have position?

PokerStars No-Limit Hold'em, $1.00 BB (7 handed) Poker-Stars Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

Hero ($101.55)
Button ($102.70)
SB ($146.75)
BB ($26.90)
UTG ($157.75)
MP1 ($115.75)
MP2 ($49)

Preflop: Hero is CO with K, K.
3 folds, Hero raises to $4, 1 fold, SB calls $3.50, 1 fold.

Flop: ($9) 6, 5, 3 (2 players)
SB bets $5, Hero raises to $15, SB calls $10.

Turn: ($39) A (2 players)
SB checks, Hero ?

hand 2: villain is Upay4college, a 100NL/200NL regular running 11/8.5/3.6 (flop AF) over 900 hands. It looked like he was in felt mode.

PokerStars No-Limit Hold'em, $1.00 BB (9 handed) Poker-Stars Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver Cards)

Button ($314.20)
SB ($120.60)
BB ($56.20)
UTG ($31.30)
UTG+1 ($162.85)
Hero ($117.45)
MP2 ($106.30)
MP3 ($108)
CO ($103.75)

Preflop: Hero is MP1 with , .
UTG calls $1, 1 fold, Hero raises to $6, 2 folds, CO calls $6, 3 folds, UTG folds.

Flop: ($14.50) , , (2 players)
Hero bets $10, CO calls $10.

Turn: ($34.50) (2 players)
Hero bets $24, CO raises to $87.75, Hero ?