1. Department of Nutritional Science and Food Management, Ewha Woman's University, Seoul 120-750, Korea
2. Department of Preventive Medicine, College of Medicine, Ewha Woman's University, Seoul 120-750, Korea
3. Department of Preventive Medicine, Dankook University College of Medicine, Cheonan 330-715, Korea
4. Department of Pediatrics, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan 682-060, Korea
5. Department of Preventive Medicine, Seoul National University College of Medicine, Seoul 110-799, Korea