Title Page

Contents

Abstract 8

제1장 Introduction 10

1. Background 10

제2장 Methods 11

1. Study design and patient population 11

2. Randomization and blinding 11

3. Study protocol and equipment 12

4. Outcome assessments 13

5. Sample size estimation and statistical analyses 14

제3장 Results 15

1. Patient characteristics 15

2. Outcomes 15

제4장 Discussion 17

제5장 Reference 20

제6장 국문초록 22

Table 1. Patient's characteristics and demographic data 24

Table 2. Primary and secondary outcomes 25