The optimal policies preventive maintenance and replacement of a machine which deteriorates as time elapses are obtained from Pontryagin's maximum principle.This study is an attempt to improve the model in the previous papers by regarding the production rate as astate veriable and deterioration of production rate as well as reduction of salvage value as obsolescence of machine.A numerical example accompanied with curves of state variables is given.

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This paper discusses the Order Entry System for determining the oprimum Parts Standerdization Ratio.In order to optimize the Parts Standerdization Ratio quantitatively, three parameters, i.e., service ratio, stock level and demand decreasing ratio are introduced, and the optimizing ratio is calculated by use of computer simulation technique.We defined an Inventory-Profit Index for the first time.The results obtained agree with those expected approximately.

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This article describes a rational system which aggregates the productivity index numbers from the lower order to the higher order.This system which has an aggregate index number form includes not only the productivity indices but also the indices of product-mix or resource allocation and it is a useful formula not only for the aggregation of the productivity indicies but also for the productivity planning of the system.The paper also examines the deficiency of currently used indicies of the same kind and proves the generality of our formula.The chief merit of the formula is its simplicity, using only basic statistical date, whice are available and are used in the day-to-day management of the factory.

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A new method of determining the number of readings in work measurement is given based on the formula in the previous paper. This paper presents also the difference between the conventional method and the proposed one.Another new formula is suggested which uses the range of initial sample.Each formula is converted into nomograph for ease determination of the number of readings.Additional information is given on the shortcut method of evaluating precision which is a very important factor in work measurement.

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Some of sampling inspection systems can be modeled by dint of the GERT network approach.This paper presents a new method of analyzing the dynamics of sampling inspection with screening.From the analysis some statistics related to the sample quantity and the outgoing quality are easily derived.An economical sampling formula is also proposed based on the cost analysis on the sampling inspection.

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The problems of employee placement have been studied as assignment problems in OR.Models of employee placement in the Japanese organization are different from those in the American organization.The models by Charnes et al.are mainly applicable to the American organization, and this paper presents some modifications to male them applicable to the Japanese organization in which qualification system and work groups play important roles.The present model is developed as a 2-stage model.The minimal-cost flow algorithm is shown for use in finding the solution.By using the present model, employee placement problems involving various kinds of information related to different aspects of personnel-to-job design will be solved.

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In the determination of the number of clerical personnel needed in an office, from the point of view of business finance, it is required that the mean of the input interval of the clerical unit be equal to the mean of the"service interval"of the clerical unit;this"service interval"is the mean of the output interval of the clerical unit when the input interval is zero.According to the Queueing theory, the clerical stagnation volume increases infinitely when the arrival rates are equal to the service rates.However, clerical activities in an office are limited by the business hours.From the results of several simulations employing the assumption that the number of clerical personnel needed is best determined when the mean of the output interval is equal to the mean of the service interval, this article points out that, under these conditions, no trouble can cause too much clerical sragnation volume.

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This paper studies the optimal forecasting method from the view-point of the mutual information.The new method is compared with the forecasting method based on the Kalman filter in the optimality.The result shows that the former generalizes the latter unless restrictive discussions are made.

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In several stages of production and sales activities, stocks as a buffer between input and output play an important role in a sense of smoothing the flow of products.The form of distribution of the inventory at the end of a period has for many years been considered a normal distribution on the assumption that a distribution of demand is normal but has little authority.This paper presents the distribution of the inventory at the end of a period, taking into account an exponential distribution of demand, exponential smoothing for forecasting, and periodic reorder rule.

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The authors hypothesize that man will learn non-linear functional relation as a certain combination of suitable linear functions, using his good sensitivity for the linear functional relations.To verify this characteristic we have made an experiment on learning of two types of non-linear functions-additive and non-additive-each of which can be expressed as a combination of two linear functions.As a result, the performance for the non-additive type is better than that of the additive type.And the manner in which the subjects are adjusted to these respective regions are different, but the existence of a boundary of the regions in their response systems is not defined clearly.

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In this report, the economy studies are presented in the case of making the selection of looms under conditions with the following items given : (1)production length per year, (2)number of looms, and(3)floor space of factory.For the better selection of looms under the given condition, (1)the comparison was made in operation between 2 shifts and 3 shifts, (2)the sensitive analyses of several factors were carried out, and(3)the effects of variations of factors were compared between two looms.

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Individual cost analysis for complicated process is coventionally managed at intervals or roughly, but we succeeded to combine it with daily production control system, using industrial engineering methods.The basic purpose of this system is to provide comparative cost data with sensitivity to product variables beyond the scope of normal cost accounting procedures.The main applications and objectives of the system are to provide product cost data for the improvement of profits through the following items of management control : a)selective selling, b)deciding the selling price, c)production planning, d)location of the points of cost reduction, e)manufacturing process control and others.

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