Due to the sewer induced ground subsidence, there is an increasing demand for the advanced visual inspection technique for the existing sewer pipe structures. This study aim to develop a visual inspection device and real-time transmission system of inspection data with precisely evaluated structural and operational conditions of underground sewer pipe structures. In this paper, a high-precision image capturing system that automatically extracts cracks in the large-diameter sewer pipes and sewage culverts with a diameter of 1,000 mm or more, a real-time gas detection sensor for investigator safety were studied. By analyzing the module technology of the visual inspection device, the concept design for system integration was derived, and the real time transmission system of the inspection result was developed to establish the technical basis for the commercialized device. Also the crack detection test using crack calibration was carried out for the proposed image capturing camera system, and the position accuracy using L1 grade GPS module was tested in this study. The inspection technique of the existing structure condition using the visual inspection device in this study can be effectively used for various structures types and advanced composite structures in the future.

ABSTRACT
 1. 서 론
 2. 육안조사용 장비의 개발
  2.1 개발방향
  2.2 개념설계
  2.3 조사장비 모듈 분석
  2.4 Wireless 실시간 정보전송 시스템
 3. 성능평가
  3.1 표면결함 감지성능 시험
  3.2 GPS 위치오차 시험
 4. 결 론
 References

• 박신전(㈜케이엠티엘 기술연구소) | Park Sinzeon
• 지기환(㈜케이엠티엘) | Jee Kee Hwan
• 유성원(가천대학교 토목환경공학과) | Yoo Sung Won