Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of Korean Institute of Industrial Engineers
Journal Basic Information
Journal DOI :
Korean Institute of Industrial Engineers
Editor in Chief :
Volume & Issues
Volume 7, Issue 2 - Dec 1981
Volume 7, Issue 1 - Jun 1981
Selecting the target year
An approximation of the M/M/s system where customers demand random number of servers
Kim, Seong-Sik ;
Journal of Korean Institute of Industrial Engineers, volume 7, issue 1, 1981, Pages 5~11
In the case of numerical implementation, the exact solution method for the M/M/s system where customers demand multiple server use  reveals limitations, if a system has large number of servers or types of customers. This is due to the huge matrices involved in the course of the calculations. This paper offers an approximation scheme for such cases. Capitalizing the characteristics of the service rate curve of the system, this method approximates the service rate as a piecewise linear function. With the service rates obtained from the linear function for each number of customers n (n=0. 1. 2,
, steady-state probabilities and measures of performance are found treating this system as an ordinary M/M/s system. This scheme performs well when the traffic intensity of a system is below about 0.8. Some numerical examples are presented.
Three Types of Inspection-Ordering Policies with Lead Times
Lee, Chang-Hun ; Kim, Ho-Gyun ;
Journal of Korean Institute of Industrial Engineers, volume 7, issue 1, 1981, Pages 13~20
Three inspection-ordering policies of a part with three types of lead times, i. e., expedited lead time, special lead time and regular lead time are considered. Policy I : The original part is replaced by a spare immediately after delivery, even if the original part is still operating. Policy II : The delivered spare is put into inventory until the original part failes. Policy III : The original part is inspected once again immediately after the delivery of the spare. If it is in a good state, the original part is used up to its mean degradation time, then replaced. If it is in a degradation state, the original part is replaced by a spare. A cost effectiveness for each policy is analyzed. Optimal inspection-ordering policy which maximizes a cost effectiveness is obtained. Time to degradation distribution and time to failure distribution are assumed to be Weibull and exponential, respectively. Variations of policies are observed with respect to variations of associated costs.
Development of a Hybrid Exponential Forecasting Model for Household Electric Power Consumption
Hwang, Hak ; Kim, Jun-Sik ;
Journal of Korean Institute of Industrial Engineers, volume 7, issue 1, 1981, Pages 21~31
This paper develops a short term forecasting model for household electric power consumption in Seoul, which can be used for the effective planning and control of utility management. The model developed is based on exponentially weighted moving average model and incorporates monthly average temperature as an exogeneous factor so as to enhance its forecasting accuracy. The model is empirically compared with the Winters' three parameter model which is widely used in practice and the Box-Jenkins model known to be one of the most accurate short term forecasting techniques. The result indicates that the developed hybrid exponential model is better in terms of accuracy measured by average forecast error, mean squared error, and autocorrelated error.
On a Special Case of a Problem in the Cumulative Damage Model
Lee, Hyo-Seong ;
Journal of Korean Institute of Industrial Engineers, volume 7, issue 1, 1981, Pages 33~36
An equipment is subject to shocks which occur randomly according to a Poisson process. The equipment fails when the total cumulative damage reaches a certain prescribed level. An optimal preventive replacement policy is presented when the level of cumulative damage cannot be checked. Renewal theory is used to obtain the results and a case example is presented.