The stocker system is another name of automated storage and retrieval system (AS/RS) and being popularly used as main material handling tools in Liquid Crystal Display (LCD) and semiconductor fabrication facilities. Recently the use of the stocker system

We consider an AS/RS(Automated Storage/ Retrieval System) which performs both of single and dual commands. The service times of single and dual commands are assumed to be differently distributed. Steady-state probabilities at the service completion epochs

As for the performance estimation of the AS/RS(Automated Storage/Retrieval System) most research assumes the AS/RS machine performs only either single command (SC) or dual command (DC) at each operation, and in addition, the type of requests is known in advance, which are not adequate in the real system. In this paper, we propose a stochastic approach for the performance estimation of a unit-load AS/RS. We assume that the service time when the AS/RS performs single command is differently distributed from that of dual command. Especially, we obtain the steady state probability distribution of the numbers of storage and retrieval commands waiting in the queues at each service completion epoch.

최근에는 수요자 요구의 다양화, 전문인력의 부족, 고임금화, 열악한 작업장에서의 작업기피 현상 등의 영향으로 인해 생산 및 물류의 자동화가 활발히 추진되고 있다. 생산 및 물류시스템의 자동화가 진전됨에 따라 전체 시스템의 물류합리화에 중요한 역할을 담당하는 자동창고 시스템에 대한 설비관리 체계 구축이 필요하게 되었고, 그 일환으로 본 연구에서는 자동창고에 대한 예방보전 및 원인진단을 지원하는 자동창고의 예방보전 및 진단시스템을 개발하였다. 특히 자동창고의 이상을 진단하는데 과거의 트러블내용을 사례로 등록시키고, 전문가가 문제해결에 사용한 경험데이타, 즉 조사항목, 조사결과 및 대처내용을 진단용 사례기반 추론베이스로 구축하여 활용하는 사례기반추론(Case Based Reasoning)방법으로 접근시켰다. 또한 자동창고시스템의 예방보전, 사후보전, 이력관리 기능을 수행할 수 있는 운영소프트웨어를 개발하였다.

Feathers are produced in huge quantities as a waste product at commercial poultry processing plants. Since feathers are almost pure keratin protein, feather wastes represent an alternative to more expensive dietary ingredients for animal feedstuffs. Generally they become feather meal used as animal feed after undergoing physical and chemical treatments. These processes require significant energy and also cause environmental pollutions. Therefore, biodegradation of feather by microorganisms represents an alternative method to prevent environment contamination. The aim of this study was to investigate cultural conditions affecting keratinolytic protease production by Bacillus pumilus RS7. We also assessed the nutritive value of microbial and alkaline feather hydrolysates. The composition of optimal medium for the keratinolytic protease was fructose 0.05%, yeast extract 0.3%, NaCl 0.05%, K2HPO4 0.03%, KH2PO4 0.04% and MgCl2ㆍ6H2O 0.01%, respectively. The optimal temperature and initial pH was 30℃ and 9.0, respectively. The keratinolytic protease production under optimal condition reached a maximum after 18 h of cultivation. Total amino acid content of feather hydrolysates treated by NaOH and B. pumilius RS7 was 113.8 ㎍/ml and 504.9 ㎍/ml, respectively. Essential amino acid content of feather hydrolysates treated by NaOH and B. pumilius RS7 was 47.2 ㎍/ml and 334.0 ㎍/ml, respectively. Thus, feather hydrolysates have the potential for utilization as an ingredient in animal feed.