A retractable bollard system has been used for the traffic control and protection of important facilities such as electric power plants, airports and government buildings etc. The power source of the driving unit of the conventional protective bollard system is on hydraulic or pneumatic system which has several disadvantages compared to an electric driven unit.
In this research, an electric driven unit for an automatic retractable bollard is designed and developed to replace the conventional hydraulic and pneumatic driven type. For the reliability test of the developed electric driven unit, a field test has been successfully done.
A case study was conducted to develop a defensive retractive bollard which the target performance is 9sec. and 7sec. on its raising and descending operation speed respectively with 750mm in stroke. The required time limit was fully satisfied as the time measured from the experiment were 7.5sec and 5.5sec for each operation. The developed unit also passed 364,000 cycles of operation without any serious malfunctions at the load test proving its reliability.
The design theory and process of an electric driven unit of the automatic retractable bollard presented in this article is believed to be very useful contribution and design tool in advancing the physical security industry.

ABSTRACT
1. 서 론
2. 자동 볼라드의 구조 및 작동원리
    2.1 볼라드 기구의 구조
    2.2 자동 볼라드의 작동원리
3. 전동볼라드 구동장치의 설계이론
    3.1 볼라드 기구의 설계이론
    3.2 볼라드 기구의 구동모터
    3.3 전동식 자동 볼라드의 설계제원
    3.4 기구 구동모터의 소요동력
4. 전동식 볼라드의 시작품 제작 및 성능시험
    4.1 전동볼라드 모델의 설계 및 제작
    4.2 전동볼라드의 성능시험 결과
5. 결 론
References

• 김철호(Seoul National University of Science & Technology) | Chul-Ho Kim Corresponding Author
• 알레마예후(Korea Institute of Industrial Technology) | Alemayehu w. Huluka
• 김영진(Korea Institute of Industrial Technology) | Young-Jin Kim
• 최성환(Korea Institute of Industrial Technology) | Seung-Hwan Choi