How i break out while loop in this case? : i don't know how to break out while loop when turtle arrived on t.ycor == 0

    import turtle
    import msvcrt

    turtle.setup(700, 300, 0, 0)
    t=turtle.Turtle()
    t.up()
    t.goto(-300,0)
    t.down()
    t.write("Start\n(" + str(t.xcor()) + ", " + str(t.ycor()) + ")", False, 
    "center", ("",15))
    while True:
            if msvcrt.kbhit():
                c = msvcrt.getch().decode(encoding = 'UTF-8')
            if c == 'j':
                t.left(3)
            elif c == 'k':
                t.right(3)
            elif c == 'g':
                t.forward(5)
                t.right(3)
            while t.ycor() > 0:
                t.forward(10)
                t.right(3)


i want to break out out side while loop when turtle arrived t.ycor == 0 after arc.
but i don't know how....