This study is designed for validation of in-vitro platelet aggregation assay using human blood in healthy volunteers. 32ml blood, 2ml for complete blood count test and 30ml for platelet aggregation assay, was collected from ten subjects, respectively.

Preparation of Platelet Rich Plasma (PRP):

1. Collect human blood using 21g butterfly syringe and dilute 9:1 into 3.8% sodium citrate vacutainer vials.
2. Prepare platelet rich plasma (PRP) by centrifuging blood at 100 x g for 15 minutes at room temperature. Using a plastic transfer pipette, carefully transfer and combine PRP from multiple vacutainer tubes (if required) into a 15 mL conical tube.
3. PRP is removed re-centrifuge remaining blood in vacutainer tubes at 2000 x g for 15 minutes at room temp. to obtain platelet poor plasma (PPP). Transfer PPP to 15 mL conical tube.
4. Measure platelet count in combined PRP using Z1 Coulter Particle Counter or similar product. Adjust platelet count to a final concentration of 300,000 +- 10,000 platelets in PRP using PPP.

Aggregation Measurement:

Aggregation is measured using a model 490-X Chrono-Log Aggregometer or similar product. PPP is used as a reference to establish 100% optical transmission.

Inclusion Criteria:

• 20-50years old
• must be able to consent voluntarily
• consent to keep the study terms of obedience

Exclusion Criteria:

• blood coagulation disorder or bleeding disorder
• blood donation within 60 days or blood transfusion within 30 days before screening
• smoker or who stopped smoking within 1month before screening
• administration of drugs such as anticoagulants or antiplatelets or alcohol within 14 days before screening
• eligibility failure under investigator's judgements

Healthy adult voulteers