This study focuses on the problem of scheduling wafer lots of several recipe(operation condition) types in the photolithography workstation in a semiconductor wafer fabrication facility, and sequence-dependent recipe set up times may be required at the ph

A typical job sequencing problem is studied in this research to improve productivities in manufacturing companies. The problem consists of two-stage parts and assembly processes. Two parts are provided independently each other and then two sequential asse

This research is to sequence flow shop with two parallel parts production and two assembly machines in sequence. Two different objective functions are studied. One is to minimize total completion time and the other is to minimize the difference of 1 job completion time and total completion time. A heuristic is designed to solve the sequencing problem. Initial solution is developed in the first stage and then the initial solution is improved in the second stage. Experimental 5 job problems are used to evaluate the performance of the suggested heuristic. The optimum solutions obtained by enumeration are used to comparisons. Also 20 job problems are generated for evaluations. 100 randomly generated sequences are evaluated and proved that the distributions are normal. And then presented how good the solutions obtained by suggested method. The initial solution stage is different for the minimization of completion time differences.

This study focuses on the problem of scheduling wafer lots of several recipe(operation condition) types in the photolithography workstation in a semiconductor wafer fabrication facility. and sequence-dependent recipe set up times may be required at the photolithography machines. In addition. a lot is able to be operated at a machine when the reticle(mask) corresponding to the recipe type is set up in the photolithography machine. We suggest various heuristic algorithms. in which developed machine selection rules and lot selection rules are used to generate reasonable schedules to minimizing the total weighted flowtime. Results of computational tests on randomly generated test problems show that the suggested algorithms outperform a scheduling method used in a real manufacturing system in terms of the total weighted flowtime of the wafer lots with ready times.

In this paper, we consider a two-machine re-entrant permutation flowshop scheduling problem with the objective of minimizing total flowtime, and suggest branch and bound algorithms for the scheduling problem. In this scheduling problem, each job must be p

Yeats and Keats differently introduced their notions of time circulation and eternal life. One expressed limitations of human which could be overcome by art. And the other introduced time flowing in harmony and peace. And in one poem, we can see something lively such as young people, birds, trees, salmon-falls, and in the other poem we can find laziness and leisure. However, there is some similarity in that they introduce the subjects of circulation of life and eternal life. Yeats shows the passage of time by the Great Wheel or gyre which develops in the course of formation, fullness, decline. And Keats also presents the passage of time by using the phrases such as “swell the gourd,” “plum the hazel shell,” “warm day will never cease.” These symbolize swelling and continuance of time. So we can find the way how time is flowing in their poems. In Yeats's “Sailing to Byzantium,” time travels from a youth to an old age, and in “To Autumn,” time travels from summer to autumn. In this circulation Yeats's immortality can be reached by the media of art. And Keats gets it by the circulation of seasons. So one continues to voyage with eagerness for Byzantium in which he could find his everlasting life through the mosaic of 15th century, and the other comfortably waits for next seasons. Two poets respectively develop their poems in different ways, but they finally achieve the same subjects of ever-lasting life in the passage of time. In conclusion, Yeats pursued immortality by separating spirit from the body, because the flesh would be decayed. On the other hand, Keats thought that the immortality could be acquired by being one with time. Unlike Yeats's “Sailing to Byzantium”, Keats's “To Autumn” has a tendency to keep harmony and reconciliation, instead of confrontation. Therefore, autumn enjoys “sitting,” and “asleep” without haste.

양전자 방출단층 촬영은 18F-FDG 주사하고 1시간 후에 촬영한다. 하지만 장비의 결함 또는 예상하지 못한 상황으 로 2-3시간정도 경과되어 촬영을 하는 경우가 발생한다. 이에 시간 흐름에 따라 획득된 영상에서 체내 부위별 표준화 섭취계수를 측정하여 다음과 같은 결과를 얻었다. 정상기관 중 정상부위는 간(간우엽 중앙부), 지방(좌측 둔부), 폐(우 측 상엽부), 대동맥(상행 대동맥)의 경우는 지연영상에서 크고 작은 감소가 나타났으며, 정상부위 중 유일하게 뼈(제 5요추 체부)에서 △SUVmax 37%의 증가가 나타났다. 병소부위는 시간의 흐름에 따라 증가함을 보였으며 △SUVmax 는 37.6%증가로 나타났으며 병소의 섭취증가와 정상부위 섭취감소로 대조도의 차이가 커짐을 알 수 있었다.