• Title/Summary/Keyword: Alternative Part Routes

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Optimal Planning of Multiple Routes in Flexible Manufacturing System (유연생산 시스템의 최적 복수 경로 계획)

  • Kim Jeongseob
    • Journal of the Korean Operations Research and Management Science Society
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    • v.29 no.4
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    • pp.175-187
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    • 2004
  • We consider the simultaneous selection of part routes for multiple part types in Flexible Manufacturing Systems (FMSs). Using an optimization framework we investigate two alternative route assignment policies. The one, called routing mix policy in the literature, specifies the optimal proportion of each part type to be produced along its alternative routes, assuming that the proportions can be kept during execution. The other one, which we propose and call pallet allocation policy, partitions the pallets assigned to each part type among the routes. The optimization framework used is a nonlinear programming superimposed on a closed queueing network model of an FMS which produces multiple part types with distinct repeated visits to certain workstations. The objective is to maximize the weighted throughput. Our study shows that the simultaneous use of multiple routes leads to reduced bottleneck utilization, improved workload balance, and a significant increase in the FMS's weighted throughput, without any additional capital investments. Based on numerical work, we also conjecture that pallet allocation policy is more robust than routing mix policy, operationally easier to implement, and may yield higher revenues.

A Look-ahead Heuristic Algorithm for Large-scale Part-Machine Grouping Problems (대단위 부품-기계 군집 문제를 위한 Look-ahead 휴리스틱 알고리듬)

  • Baek Jong-Kwan;Baek Jun-Geol;Kim Chang Ouk
    • Journal of the Korean Operations Research and Management Science Society
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    • v.30 no.3
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    • pp.41-54
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    • 2005
  • In this paper, we consider a multi-objective machine cell formation problem. This problem Is characterized as determining part route families and machine cells such that total sum of inter-ceil part movements and maximum machine workload imbalance are simultaneously minimized. Together with the objective function, alternative part routes and the machine sequences of part routes are considered In grouping Part route families. Due to the complexity of the problem, a two-phase heuristic algorithm is proposed. And we developed an n-stage look-ahead heuristic algorithm that generalizes the roll-out algorithm. Computational experiments were conducted to verify the performance of the algorithm.

Integrating Machine Reliability and Preventive Maintenance Planning in Manufacturing Cell Design

  • Das, Kanchan;Lashkari, R.S.;Sengupta, S.
    • Industrial Engineering and Management Systems
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    • v.7 no.2
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    • pp.113-125
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    • 2008
  • This paper presents a model for designing cellular manufacturing systems (CMS) by integrating system cost, machine reliability, and preventive maintenance (PM) planning. In a CMS, a part is processed using alternative process routes, each consisting of a sequence of visits to machines. Thus, a level of 'system reliability' is associated with the machines along the process route assigned to a part type. Assuming machine reliabilities to follow the Weibull distribution, the model assigns the machines to cells, and selects, for each part type, a process route which maximizes the overall system reliability and minimizes the total costs of manufacturing operations, machine underutilization, and inter-cell material handling. The model also incorporates a reliability based PM plan and an algorithm to implement the plan. The algorithm determines effective PM intervals for the CMS machines based on a group maintenance policy and thus minimizes the maintenance costs subject to acceptable machine reliability thresholds. The model is a large mixed integer linear program, and is solved using LINGO. The results point out that integrating PM in the CMS design improves the overall system reliability markedly, and reduces the total costs significantly.

Conceptual Design of Automatic Control Algorithm for VMSs (VMS 자동제어 알고리즘 설계)

  • 박은미
    • Journal of Korean Society of Transportation
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    • v.20 no.7
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    • pp.177-183
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    • 2002
  • Current state-of-the-art of VMS control is based upon simple knowledge-based inference engine with message set and each message's priority. And R&Ds of the VMS control are focused on the accurate detection and estimation of traffic condition of the subject roadways. However VMS display itself cannot achieve a desirable traffic allocation among alternative routes in the network In this context, VMS display strategy is the most crucial part in the VMS control. VMS itself has several limitations in its nature. It is generally known that VMS causes overreaction and concentration problems, which may be more serious in urban network than highway network because diversion should be more easily made in urban network. A feedback control algorithm is proposed in this paper to address the above-mentioned issues. It is generally true that feedback control approach requires low computational effort and is less sensitive to models inaccuracy and disturbance uncertainties. Major features of the proposed algorithm are as follows: Firstly, a regulator is designed to attain system optimal traffic allocation among alternative routes for each VMS in the network. Secondly, strategic messages should be prepared to realize the desirable traffic allocation, that is, output of the above regulator. VMS display strategy module is designed in this context. To evaluate Probable control benefit and to detect logical errors of the Proposed feedback algorithm, a offline simulation test is performed using real network in Daejon, Korea.

Appropriateness of Bed Utilization in One University Hospital (병상 이용의 적절성에 영향을 미치는 요인에 관한 연구 -한 대학병원 자료를 중심으로-)

  • 이상일;김용익;신영수
    • Health Policy and Management
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    • v.3 no.1
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    • pp.1-24
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    • 1993
  • This study is designed to find clues to make a plan for efficient hospital bed utilization. Author has tried to estimate the level of appropriateness and to find out factors affecting intra-hospital variation of inappropriate bed utilization using modified Appropriateness Evaluation Protocol of which criteria are based on service intensity and patients' conditions. Systematic random sampling was done from the population of inpatients during one month in on university hospital. Data were collected by concurrent and retrospective medical record review and analysed by multiple logistic regression. In medical services, 83.5% of admission reveals appropriate and the level of inappropriate admission shows significant differences by patients' residence, type of department admitted to, admission 개\ulcorner, and length of stay. In surgical services, 97.3% and 34.7% are appropriate in location and timing of surgery respectively. Inappropriate timing of surgery differs significantly depending on patients' age, type of department admitted to, admission route, and length of stay. Sixty two percent of hospital days shows appropriate and the level of inappropriateness show marked differences by patients'age, type of services, admission routes, part of the month, part of the stay, and length of stay. Inappropriate hospital days are due to inappropriate level of care, premature admission, improper scheduling of diagnostic or therapeutic procedures, and problems in scheduling surgery in sequence. In conclusion, substantially high proportion of inappropriate hospital bed utilization was confirmed. To reduce it, it is necessary to develop alternative services with which can replace inpatient services, and to introduce utilization management system which may include internal peer review.

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A Study on Improvement Plan of City Bus Kindness Service (시내버스 친절서비스 향상 방안에 대한 연구)

  • Lee, Jeong Hun;Jung, Hun Young;Shin, Kangwon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.37 no.2
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    • pp.369-377
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    • 2017
  • The city of Busan implemented the 'Bus Quasi-Public Operating System' as a part of the Public Transit Activation Policy. Although the reorganization of routes and fares had temporarily increased the number of passengers, it is facing a downtrend currently. This implies the limited capability of increasing the use of the city buses only by adjusting the systematic components of the system. Thus, the research aims to analyse the effect of improving the 'kindness service' as an alternative way to vitalize the use of city buses. The analysis uses the survey encompassing sixteen 'kindness service' factors that was collected from the passengers and the drivers of the city buses in Busan, and some of the notable findings are followed. According to the analysis of determining the level of importance on the 'kindness service' factors, four major categories were derived; a category to maintain/reinforce the kindness service, a category to make incremental improvement, a category to encourage improvement, and a category to make focusing improvement. Using the categories, the study then performed the cluster analysis on 33 city bus companies in Busan to determine the differences between the companies. Consequently, the companies were grouped into four; two groups (14 companies) showing more importance on the kindness service while the other two groups (19 companies) showing less. In addition, multivariate an analysis of variance (MANOVA) identified the significant differences of the four categories among the groups of companies, and the findings were taken into consideration on further improvement plans of kindness service in the city buses of Busan.

An Exploratory Study on the Components of Visual Merchandising of Internet Shopping Mall (인터넷쇼핑몰의 VMD 구성요인에 대한 탐색적 연구)

  • Kim, Kwang-Seok;Shin, Jong-Kuk;Koo, Dong-Mo
    • Journal of Global Scholars of Marketing Science
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    • v.18 no.2
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    • pp.19-45
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    • 2008
  • This study is to empirically examine the primary dimensions of visual merchandising (VMD) of internet shopping mall, namely store design, merchandise, and merchandising cues, to be a attractive virtual store to the shoppers. The authors reviewed the literature related to the major components of VMD from the perspective of the AIDA model, which has been mainly applied to the offline store settings. The major purposes of the study are as follows; first, tries to derive the variables related with the components of visual merchandising through reviewing the existing literatures, establish the hypotheses, and test it empirically. Second, examines the relationships between the components of VMD and the attitude toward the VMD, however, putting more emphasis on finding out the component structure of the VMD. VMD needs to be examined with the perspective that an online shopping mall is a virtual self-service or clerkless store, which could reduce the number of employees, help the shoppers search, evaluate and purchase for themselves, and to be explored in terms of the in-store persuasion processes of customers. This study reviewed the literatures related to store design, merchandise, and merchandising cues which might be relevant to the store, product, and promotion respectively. VMD is a total communication tool, and AIDA model could explain the in-store consumer behavior of online shopping. Store design has to do with triggering a consumer attention to the online mall, merchandise with a product related interest, and merchandising cues with promotions such as recommendation and links that induce the desire to pruchase. These three steps might be seen as the processes for purchase actions. The theoretical rationale for the relationship between VMD and AIDA could be found in Tyagi(2005) that the three steps of consumer-oriented merchandising are a store, a product assortment, and placement, in Omar(1999) that three types of interior display are a architectural design display, commodity display, and point-of-sales(POS) display, and in Davies and Ward(2005) that the retail store interior image is related to an atmosphere, merchandise, and in-store promotion. Lee et al(2000) suggested as the web merchandising components a merchandising cues, a shopping metaphor which is an assistant tool for search, a store design, a layout(web design), and a product assortment. The store design which includes differentiation, simplicity and navigation is supposed to be related to the attention to the virtual store. Second, the merchandise dimensions comprising product assortments, visual information and product reputation have to do with the interest in the product offerings. Finally, the merchandising cues that refer to merchandiser(MD)'s recommendation of products and providing the hyperlinks to relevant goods for the shopper is concerned with attempt to induce the desire to purchase. The questionnaire survey was carried out to collect the data about the consumers who would shop at internet shopping malls frequently. To select the subject malls, the mall ranking data announced by a mall rating agency was used to differentiate the most popular and least popular five mall each. The subjects was instructed to answer the questions after navigating the designated mall for five minutes. The 300 questionnaire was distributed to the consumers, 166 samples were used in the final analysis. The empirical testing focused on identifying and confirming the dimensionality of VMD and its subdimensions using a structural equation modeling method. The confirmatory factor analysis for the endogeneous and exogeneous variables was carried out in four parts. The second-order factor analysis was done for a store design, a merchandise, and a merchandising cues, and first-order confirmatory factor analysis for the attitude toward the VMD. The model test results shows that the chi-square value of structural equation is 144.39(d.f 49), significant at 0.01 level which means the proposed model was rejected. But, judging from the ratio of chi-square value vs. degree of freedom, the ratio was 2.94 which smaller than an acceptable level of 3.0, RMR is 0.087 which is higher than a generally acceptable level of 0.08. GFI and AGFI is turned out to be 0.90 and 0.84 respectively. Both NFI and NNFI is 0.94, and CFI 0.95. The major test results are as follows; first, the second-order factor analysis and structural equational modeling reveals that the differentiation, simplicity and ease of identifying current status of the transaction are confirmed to be subdimensions of store design and to be a significant predictors of the dependent variable. This result implies that when designing an online shopping mall, it is necessary to differentiate visually from other malls to improve the effectiveness of the communications of store design. That is, the differentiated store design raise the contrast stimulus to sensory organs to promote the memory of the store and to have a favorable attitude toward the VMD of a store. The results that navigation which means the easiness of identifying current status of shopping affects the attitude to VMD could be interpreted that the navigating processes via the hyperlinks which is characteristics of an internet shopping is a complex and cognitive process and shoppers are likely to lack the sense of overall structure of the store. Consequently, shoppers are likely to be alost amid shopping not knowing where to go. The orientation tool enhance the accessibility of information to raise the perceptive power about the store environment.(Titus & Everett 1995) Second, the primary dimension of merchandise and its subdimensions was confirmed to be unidimensional respectively, have a construct validity, and nomological validity which the VMD dimensions supposed to have a positive correlation with the dependent variable. The subdimensions of product assortment, brand fame and information provision proved to have a positive effect on the attitude toward the VMD. It could be interpreted that the more plentiful the product and brand assortment of the mall is, the more likely the shoppers to favor it. Brand fame and information provision as well affect the VMD attitude, which means that the more famous the brand, the more likely the shoppers would trust and feel familiar with the mall, and the plentifully and visually presented information could have the shopper have a favorable attitude toward the store VMD. Third, it turned out to be that merchandising cue of product recommendation and hyperlinks affect the VMD attitude. This could be interpreted that recommended products could reduce the uncertainty related with the purchase decision, and the hyperlinks to relevant products would help the shopper save the cognitive effort exerted into the information search and gathering, which could lead to a favorable attitude to the VMD. This study tried to sheds some new light on the VMD of online store by reviewing the variables mentioned to be relevant with offline VMD in the existing literatures, and tried to link the VMD components from the perspective of AIDA model. The effect size of the VMD dimensions on the attitude was in the order of the merchandise, the store design and the merchandising cues.It is said that an internet has an unlimited place for display, however, the virtual store is not unlimited since the consumer has a limited amount of cognitive ability to process the external information and internal memory. Particularly, the shoppers are likely to face some difficulties in decision making on account of too many alternative and information overloads. Therefore, the internet shopping mall manager should take into consideration the cost of information search on the part of the consumer, to establish the optimal product placements and search routes. An efficient store composition would be possible by reducing the psychological burdens and cognitive efforts exerted to information search and alternatives evaluation. The store image is in most part determined by the product category and its brand it deals in. The results of this study support this proposition that the merchandise is most important to the VMD attitude than other components, the manager is required to take a strategic approach to VMD. The internet users are getting more accustomed and more knowledgeable about the internet media and more likely to accept the internet as a shopping channel as the period of time during which they use the internet to shop become longer. The web merchandiser should be aware that the product introduction using a moving pictures and a bulletin board become more important in order to present the interactive product information visually and communicate with customers more actively, therefore leading to making the quantity and quality of product information more rich.

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