After written consent for participating in clinical research studies, all clinical studies conducted to in the one day. The investigators will ask and record about bowel cleansing state in all patients who performed colonoscopy. There is no additional cost and the expected complications.

Based on answer, the investigators will develop a prediction model for inadequate bowel preparation and prove validation. This model can take the additional measures to subjects predicting improper cleansing. It can contribute to improve the accuracy of the test and reduce the discomfort due to re-performing colonoscopy after re-preparation, as well as cost savings due to reduced frequency of re-colonoscopy Ultimately, it will be able to bring a improvement of the quality of management

Inclusion Criteria:

• Adults over 20 years old

Exclusion Criteria:

• Less than 20 years old
• Cardiac, renal, and metabolic dysfunction in patients with serious adverse
• Mental or central nervous system disorders
• Individuals with bwel obstruction
• Individuals who can not read and understand the consent form (literacy, foreign, etc.) However, although individuals with vision / hearing disturbance and deterioration of cognitive abilities, they may participate in the research if can be able to complete the survey with one guardian or the help of researchers.

healthy subjects, more than 20 years old, who admitted to the health promotion center for performing colonoscopy.