• IE interfaces
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• 제24권3호
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• pp.241-247
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• 2011

This paper develops a mathematical model which searches an optimum lot size of a press line, and applies this model to the scheduling of the press line. This mathematical model is not a widely studied cost model but a model which considers the utilization of the press line under a lean production system. In this paper, the optimum lot size is a minimum lot size which does not exceed the total work time of the press line. A production volume and the priority of the production in the press line are adjusted using this optimum lot size. A mathematical model developed in this paper will allow determining the optimum lot size easily in case of variable production environments such as an introduction of a new product and a fluctuation of production volume of each item. Therefore, our model will make a better scheduling of the press line and will enhance the utilization of it.

• Korean Management Science Review
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• 제31권3호
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• pp.27-39
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• 2014

We derive a generalized statistic form of Q control chart, which is especially suitable for short run productions and start-up processes, for the detection of process mean shifts. The generalization means that the derived control chart statistic concurrently uses within lot variability and between lot variability to explain the process variability. The latter variability source is noticeably prevalent in lot type production processes including semiconductor wafer fabrications. We first obtain the generalized Q control chart statistic when both the process mean and process variance are unknown, which represents the case of implementing statistical process control charting for short run productions and start-up processes. Also, we provide the corresponding generalized Q control chart statistics for the rest of three cases of previous Q control chart statistics : (1) both the process mean and process variance are known (2) only the process mean is unknown and (3) only the process variance is unknown.

• Journal of Korean Society for Quality Management
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• 제21권1호
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• pp.108-120
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• 1993

In this article an economic life test sampling plan is considered for repairable products when the products in each lot have the same interfailure time distribution, but the mean time between failure (MTBF) of a lot varies from lot to lot according to a known prior distribution. A cost model is constructed which consists of test cost, accept cost, and reject cost. Determination of the optimal plan which minimizes the expected average cost per lot is discussed. Numerical examples are presented to illustrate the use of the proposed sampling plans and sensitivity analyses for parameters of the prior distribution are performed.

• Journal of Korean Society of Industrial and Systems Engineering
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• 제18권35호
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• pp.39-46
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• 1995

This study is to find the optimal lot size method in the distribution system. In general, the lot size methods used in the distribution system is the same as the methods of the MRP system. The lot size methods used in this study are LFL, EoQ, LTC and POQ.. Resulting in case study, LTC is the optimal lot size method in the distribution system. In distribution system, VRP and VSP shall be investgated.

• Land and Housing Review
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• 제10권4호
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• pp.13-30
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• 2019

Parking lot within housing site contains public interest of relieving parking space shortage problem and subject to public restriction. If auctioned off at higher price by excessive competition in general competitive bid for land bidders, the development of parking lot will be made against its original purpose supply. The core issue is that a bid price is quite often to be blown out of proportion by 150%~ 250% due to extreme competition and, could face serious problem if a winning bidder runs sale business. If it is rental business, although about 30% of the total floor space of the whole building to be used as neighborhood facilities, too high winning bid price cause to lose transparency. In case of sale at aggregate buildings, most business operators would sell 30% of the neighborhood facilities, spare the parking lot and manages thereof separately. According to Aggregate Buildings Act, neighborhood facilities are allowed for individual registration and ownership of parking lot by business operator or designated person by business operator. In this case, the parking lot becomes 70% of the total floor space of the whole building and 70% of the land share which makes the mortgage very valuable and easier for business operator to get financial loan. There used to be many cases such as owners of neighborhood facilities (aggregate buildings partial owners) who run parking lot to repay their loan running parking lot to repay loan, but found that very tough and reached auction and relatively disadvantaged. For parking lot within housing site, it is recommend to exclude the public factors that land has and take into account of public restriction in area (housing site). Business opportunity for operators and protection of property rights for buyers in aggregate buildings, land supply method is recommended to replace from highest bid method into draw or private contract. In terms of price, supply at estimated price (construction price) and restriction on usage (Co-ownership of parking lot) proposals are submitted.

• Journal of Industrial Technology
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• 제20권A호
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• pp.219-228
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• 2000

The determination of lot sizes in prevailing inventory problems has been made with constant safety stock over the planning horizon. But, it is more profitable to accommodate the safety stock to dynamically fluctuating demands. The objective of this paper is to study the method to determine the dynamic safety stock and lot sizing rules depending on the actual customer demands. The last period or highly fluctuating period during the consumption of a lot is the most critical one to stock-out. It means that such periods must be given more attentions. Some dynamic methods to control safety stock are proposed with viewpoints of the time, quantity, and time-quantity. Simulation results show that lot sizing methods with dynamic safety stock reduce about 10% of average total cost compared to those with constant safety stock.

• Journal of the Korean Operations Research and Management Science Society
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• 제40권3호
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• pp.23-38
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• 2015

In this paper, we evaluate the strength of three families of cutting planes for a lot-sizing problem. Lot-sizing problem is very basic MIP model for production planning and many strong valid inequalities have been developed for a variety of relaxations in the literature. To use three families of cutting planes in Branch-and-Cut framework, we develop separation algorithms for each cut and implement them in CPLEX. Then, we perform computational study to compare the effectiveness of three cuts for randomly generated instances of the lot-sizing problem.

• The Journal of Society for e-Business Studies
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• 제9권2호
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• pp.123-143
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• 2004

Nowadays, insufficient parking lots give rise to a serious problem. Cars are increased in geometrical progression, but parking lots that takes in cars are relatively limited. Often we spend a lot of time to look for a parking lot because of limited parking lot. To solve this problem, we can use real time parking lot information system provided from mobile vehicles. In this paper, we will tell you how to deliver the parking lot information in real time by construction wireless network environment to be provided real time information and making XML data that is easy to share and to exchange data between applications.

• Journal of Korean Society of Industrial and Systems Engineering
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• 제37권4호
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• pp.187-192
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• 2014

Lot-streaming is the process of splitting a job (lot) into sublots to allow the overlapping of operations between successive machines in a multi-stage production system. A new genetic algorithm (NGA) is proposed for an n-job, m-machine, lot-streaming flow shop scheduling problem with equal-size sublots in which the objective is to minimize the total stretch. The stretch of a job is the ratio of the amount of time the job spent before its completion to its processing time. NGA replaces the selection and mating operators of genetic algorithms (GAs) by marriage and pregnancy operators and incorporates the idea of inter-chromosomal dominance and individuals' similarities. Extensive computational experiments for medium to large-scale lot-streaming flow-shop scheduling problems have been conducted to compare the performance of NGA with that of GA.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 한국건설관리학회 2007년도 정기학술발표대회 논문집
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• pp.1039-1042
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• 2007

The number of vehicle has been increased due to growth of economy. Consequently, the needs for parking area has been increasing. there is a serious problem in aged-apartments. It result from observing a parking lot law at that times. That is the reason why residents demand parking lot expansion. Parking lot addition is being studied on a lots different standpoint to solve the present parking lot condition. Parking lot expansion is limited by housing complex characteristics. This study analyzed the housing complex characteristics of aged-apartment. It is analyzed that the number of house holders, distance between buildings, and level of site for finding housing complex characteristics. The result are as follows. the complex lower than 300 households is about 35% in the Number of households. The buildings which has a moving distance from 41m to 50 is nearly 23%. Them the 멕스둣 house located on the flat is 82%. This study will become a reference data for the parking lot expansion.