As power consumption increases, more power utilities are required to satisfy the demand and consequently results in tremendous cost to build the utilities. Another issue in construction of power utilities to meet the peak demand is an inefficiency caused by surplus power during non-peak time. Therefore, most power company considers power demand management with time-based electricity rate policy which applies different rate over time. This paper considers an optimal machine operation problem under the time-based electricity rates. In TOC (Theory of Constraints), the production capacities of all machines are limited to one of the bottleneck machine to minimize the WIP (work in process). In the situation, other machines except the bottleneck are able to stop their operations without any throughput loss of the whole manufacturing line for saving power utility cost. To consider this problem three integer programming models are introduced. The three models include (1) line shutdown, (2) block shutdown, and (3) individual machine shutdown. We demonstrate the effectiveness of the proposed IP models through diverse experiments, by comparing with a TOC-based machine operation planning considered as a current model.

1. 서 론
 2. Drum-Buffer-Rope(DBR)
 3. 시간대별 차등 전기요금을 고려한 장비운용계획 모형
  3.1 라인 셧다운 모형
  3.2 공정 블록 제어 모형
  3.3 개별 기계 제어 모형
 4. 실험 분석
  4.1 모형별 성능 비교
  4.2 제조 환경 변화에 따른 모형별 분석
 5. 결론 및 향후 연구과제
 Acknowledgement

• 김인호(홍익대학교 산업공학과) | Inho Kim
• 옥창수(홍익대학교 산업공학과) | Changsoo Ok Corresponding Author