• Journal of the Korean Operations Research and Management Science Society
• /
• v.32 no.1
• /
• pp.137-146
• /
• 2007

In this study we consider a CONWIP system studied in Park and Lee [1] in which the processing times at each station follow a Coxian distribution and the demands for the finished products arrive according to a compound Poisson process. The demands that are not satisfied Immediately are either backordered or lost according to the number of demands that exist at their arrival instants. For this system using the results in [1] we develop an approximation method to calculate order based performance measures such as the mean time of fulfilling a customer order and the mean number of customer orders. To test the accuracy of the approximation method, the results obtained from the approximation method are compared with those obtained by simulation. Comparisons with simulation have shown that the approximate method provides fairly good results.

• Journal of the Ergonomics Society of Korea
• /
• v.25 no.3
• /
• pp.85-96
• /
• 2006

Main control room(MCR) man-machine interface(MMI) design of advanced nuclear power plants(NPPs) such as APR(advanced power reactor)-1400 can be validated through performance-based tests to determine whether it acceptably supports safe operation of the plant. In this work, plant performance, personnel task, situation awareness, workload, teamwork, and anthropometric/physiological factor are considered as factors for the human performance evaluation. For development of measures in each of the factors, techniques generally used in various industries and empirically proven to be useful are adopted as main measures and some helpful techniques are developed in order to complement the main measures. Also the development of the measures is addressed based on the theoretical background. Finally we discuss the way in which the measures can be effectively integrated and then HUPESS(HUman Performance Evaluation Support System) which is in development based on the integrated way is briefly introduced.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2004.10a
• /
• pp.8-12
• /
• 2004

In this study we consider a CONWIP system in which the processing times at each station follow a Coxian distribution and the demands for the finished products arrive according to a compound Poisson process. The demands that are not satisfied are backordered according to the number of demands that exist at their arrival instants. For this system we develop an approximation method to calculate order based performance measures such as the mean time of fulfilling a customer order and the mean number o: customer orders. For the analysis of the proposed CONWIP system, we model the CONWIP system as a closed queueing network with a synchronization station and analyze the closed queueing network using a product form approximation method. Numerical tests show that the approximation method provides fairly good estimation of the performance measures of interest.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.7 no.3
• /
• pp.640-653
• /
• 2015

In order to develop the challenging process of placing Aids to Navigation (AtoN), we propose performance measures which quantifies the effect of such placement. The best placement of AtoNs is that from which the navigator can best recognize the information provided by an AtoN. The visibility of AtoNs depends mostly on light sources, the weather condition and the position of the navigator. Visual recognition is enabled by achieving adequate contrast between the AtoN light source and background light. Therefore, the performance measures can be formulated through the amount of differences between these two lights. For simplification, this approach is based on the values of the human factor suggested by International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA). Performance measures for AtoN placement can be evaluated through AtoN Simulator, which has been being developed by KIOST/KRISO in Korea and has been launched by Korea National Research Program. Simulations for evaluation are carried out at waterway in Busan port in Korea.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2003.09a
• /
• pp.563-566
• /
• 2003

Quality measures play an important role in the field of image processing. Such measures are commonly used to assess the performance of different algorithms that are designed to perform a specific image processing task. In this paper we propose two novel measures for image quality assessment based on the notion of correlation between fuzzy sets. Two different definitions fur the correlation between fuzzy sets have been used. In order to calculate the proposed quality measures two approaches were evaluated, one with direct application of the measures to the image′s pixels and the other using the fuzzy set corresponding to the normalized histogram of the image. A comparative study of the proposed measures is performed by investigating their behavior using images with different types of distortions, such as impulsive "salt at pepper" noise, additive white Gaussian noise, multiplicative speckle noise, blurring, gamma distortion, and JPEG compression.

• Journal of Korea Trade
• /
• v.27 no.3
• /
• pp.199-216
• /
• 2023

Purpose - This study aims to identify the internal capabilities that export companies need to possess in order to utilize FTAs and to propose ways to expand their export performance through them. To achieve this goal, the study analyzed the internal factors that affect FTA utilization from a resource-based perspective, such as Origin Management Competency, Information Acquisition Competency, contract Management Competency, and Commitment to Export, based on prior research on corporate capabilities in the field of management and FTA-related research. The study ultimately aims to confirm whether a company's FTA utilization contributes to its export performance through the management and response to its internal factors for FTA utilization. Design/methodology - To achieve the research objective, this study conducted a literature review related to FTA utilization and identified the internal factors of companies that affect FTA by classifying them into Origin Management Competency, Information Acquisition Competency, contract Management Competency, and Commitment to Export Based on this, a final research model was developed, hypotheses were set through a preliminary study survey, and conclusions were drawn by analyzing the data of 312 companies. Findings - The empirical analysis results indicate that Origin Management Competency and Contract Management Competency have a positive impact on FTA utilization, while Information Acquisition Competency and Commitment to Export do not have a statistically significant impact on FTA utilization. Based on these findings, this study suggests measures for efficient FTA utilization for companies that want to utilize FTAs. Additionally, FTA utilization has a positive impact on export performance. In other words, the extent to which companies utilize the signed agreements has a positive impact on their performance. Based on these results, this study identifies the characteristics of companies that want to utilize FTAs and proposes measures for future efficient FTA utilization. Originality/value - This study has confirmed that in order for companies to utilize FTAs, they must meet the requirements of the FTA. To this end, the study has concluded that it is important to manage and address internal factors such as Origin Management Competency, Information Acquisition Competency, contract Management Competency, and Commitment to Export to increase FTA utilization. Based on these results, it can be confirmed that it is essential for companies to have an understanding and management of the internal factors that satisfy the requirements of the FTA in order to utilize the FTA.

• Journal of Korean Society for Quality Management
• /
• v.23 no.4
• /
• pp.1-12
• /
• 1995

Sample skewness has not received much attention from researchers to design a control chart. In this paper, control charts based on two skewness measures are studied to control a manufacturing process. One skewness measure is the third central moment about mean, the other is the third L-moment which is a linear combination of order statistics. Since the exact sampling distributions of two skewness measures are unknown, empirical sampling distributions are studied using simulation. The sampling distributions are used to design control charts for skewness and performance of two skewness measures is compared.

• Korean Journal of Mathematics
• /
• v.29 no.2
• /
• pp.371-386
• /
• 2021

This paper investigates two discrete time queueing inventory models with positive service time and lead time. Customers arrive according to a Bernoulli process and service time and lead time follow geometric distributions. The first model under discussion based on replenishment of order upto S policy where as the second model is based on order placement by a fixed quantity Q, where Q = S - s, whenever the inventory level falls to s. We analyse this queueing systems using the matrix geometric method and derive an explicit expression for the stability condition. We obtain the steady-state behaviour of these systems and several system performance measures. The influence of various parameters on the systems performance measures and comparison on the cost analysis are also discussed through numerical example.

• Korean Journal of Construction Engineering and Management
• /
• v.5 no.4 s.20
• /
• pp.79-86
• /
• 2004

One of the most difficult tasks in pavement management information systems is establishing the links between performance measures of a structure and the design and construction inputs. In-situ pavement performance can be considered a response variable to many project input variables, such as design, construction, and traffic loading effects. If we are to fully understand the component of pavement performance and specify the inputs through design and construction specifications to achieve that performance we must develop quantitative relationship between input and response variables through a scientific, fully integrated Pavement Performance Analysis System (PPAS). Hence, the objective of this study is to design a database model required for developing an effective database template that will allow analysis of pavement performance measures based on design and construction information linked by location. In order to select the most appropriate database model, a conceptual database model (Entity Relationship Model) and dimensional model, which is believed to be the most effective modeling technique for data warehouse project, are designed and compared. It is believed that other state highway agencies could adopt the proposed design strategy for implementing a PPAS at the discretion of the state highway agencies.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.14 no.1
• /
• pp.57-62
• /
• 2004

We have proposed an efficient method of word separation in a handwritten legal amount on bank check based on the spatial gaps between the connected components. The previous gap measures all suffer from the inherent problem of underestimation or overestimation that causes a deterioration in separation performance. In order to alleviate such burden, we have developed a modified version of each distance measure. Also, 4 class clustering based method of integrating three different types of distance measures has been proposed to compensate effectively the errors in each measure, whereby further improvement in performance of word separation is expected. Through a series of word separation experiments, we found that the modified distance measures show a better performance with over 2 - 3% of the word separation rate than their corresponding original distance measures. In addition, the proposed combining method based on 4-class clustering achieved further improvement by effectively reducing the errors common to two of three distance measures as well as the individual errors.