System Information
Operating system: win7
Graphics card: geforce gtx 1060 6g

Blender Version
Broken: (example: 2.80, edbf15d3c044, master, 2018-11-28, as found on the splash screen)
Worked: (optional)

Short description of error

1. cycle engine render & viewport shading mode -> shadow not smooth ->
2. shade smooth apply -> object data auto smooth apply 180 -> shadow not smooth
3. render context Apply this and that test -> not smooth
4. light context Apply this and that test -> not smooth
5. preferences lights Apply this and that test -> not smooth
6. object Part Shadow looks similar to shade flat

1. (사이클 렌더링과 쉐이딩모드에서 그림자가 부드럽지 않고 엣지 부분 부터 그림자가 생성되는지 계단처럼 그려짐니다. shade smooth, auto smooth 180 적용 해봐도 변하지않아
2. render context, light context, preferences lights 부분에서 이것저것 눌러 보고 렌더링 해봤지만 계속 일부분 그림자가 shade flat 처럼 나타납니다.

Exact steps for others to reproduce the error
Based on the default startup or an attached .blend file (as simple as possible).