Post stroke hemiplegia patient have shoulder subluxation in affected side. The investigators use functional electrical stimulation in posterior deltoid and supraspinatus for prevention and treatment. But the investigators hypothesis self triggered myoelectric stimulation system has more effective for shoulder subluxation. The purpose of this study is to compare post-stroke shoulder subluxation treatment FES and triggered FES.

Inclusion Criteria:

1. Within 3months after stroke
2. 1st stroke patients with hemiplegic shoulder subluxation which is measured above one finger breadth by physical examination
3. Shoulder abduction strength is above P- grade (MMT)
4. Male or female, ≥ 20 years of age
5. Written informed consent has beed obtained
6. Patients who understand purpose of this study and conform with intervention process

Exclusion Criteria:

1. Quadriplegia or double hemiplegia
2. History of injury, surgery, etc. of U/E and upper chest area
3. person who implanted metalic device(ex. pacemaker, vagus nerve stimulator)
4. patients who have lower motor neuron lesion
5. person who have difficulty using electrode due to skin problem such as skin ulcer or open wound
6. who have seizure or epilepsy history
7. Female who are pregnant