• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2368-2374
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• 2013

Elevator power consists of power consumption in stand-by and in service. This paper designed a fuzzy controller saving stand-by power of elevators in a way that calculates the adequate number of elevators by the variable traffic volume of passenger and then powers off elevators being out of service. Also, the fuzzy controller was designed to minimize a increase of the average passenger's waiting time by the limited number of elevators in service. When the fuzzy controller designed in this paper was applied to the group elevator experimental device, The passenger's waiting time increased approximately 7.5%~9.5%, While the stand-by power saving is expected to be about 675KWh a day per unit and about 236.6KWh a year per unit.

• YAKHAK HOEJI
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• v.49 no.6
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• pp.449-458
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• 2005

There have been rapid changes in the pharmaceutical environment after the separation of Dispensing and Prescribing practice. In the early stage of this system, outpatients had few options to choose their pharmacies due to various obstacles. Under these circumstances, this study on the defection tendency of long-term care patients was performed through the analysis of outpatients who quit visiting a pharmacy nearby general hospital. PowerBuilder ver 9.0 program was used to extract significant data, and SPSS package was employed for statistic analysis. 3,308 outpatients who visited a pharmacy nearby hospital for a month (in January, 2004) were studied. Patients' sex, age and location of residence, the class of medical insurance, the characteristic type of medication (powder, split form, medication for external use/injection), waiting time, disease (department) were considered as variable factors. It turned out that the patient revisit ratio was 80.8$\%$ and the patient defection ratio was 32.4$\%$. As was expected, those factors mentioned above influenced on the revisit and defection ratio considerably. In terms of patient factors, it proved that there was no relationship among sex, location of residence, the class of medical insurance and revisit (defection) ratio. Only age factor influenced the ratio; the older, the higher revisit ratio and the less defection ratio. In respect of dispensing factors, there were obvious relationships among the factors and the ratio: bill (money they had to pay individually), waiting time, number of medications, splitting of tablets, unit price of drug and revisit (defection) ratio showed significant relationship. The result of this study revealed an aspect of outpatients' behavior and it could be used as a reference for better patient service and customer relationship management.

• Journal of Korean Society of Transportation
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• v.28 no.2
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• pp.77-85
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• 2010

As the ticket issuing methods have been diversified for the convenience of the passengers such as ticketless service(SMS ticket, e-ticket, home ticket), automatic ticket issuing machine and consignment ticket sale, maintaining the current number of ticket booth has been becoming a issue. This study is designed to simulation for the optimum number of ticket booth and which can affect an efficient operation of train station and improvement of customer convenience. This study will contribute to minimize customer waiting time at the ticket booth. In addition, presenting the optimum number of booth is expected to have an effect on the increase of productivity and cost savings.

• Quality Improvement in Health Care
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• v.20 no.1
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• pp.28-40
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• 2014

Objectives: Prescriptions for Parkinson's can be dispensed at the outpatient pharmacy. In general, the treatment of Parkinson's disease requires a multitude of drugs, sometimes taken 4 to 6 times a day at specific times as prescribed by the medical practitioner. Said "time-specific therapy" is one of the major reasons of dispensing delay observed at the outpatient pharmacy. Because our establishment lacked a computerized system to support time-specific prescriptions, they were not recognized electronically. They had to be issued and dispensed manually, which required a greater amount of time than the automated process. To solve the problem, a new sig code was developed to handle time-specific prescriptions with a comprehensive automated dispensing system to support it. This study aims to create electronic programs and streamline the process to increase dispensing performance. And thus, ensure greater patient safety and dispensing accuracy within a shorter dispensing time and also increase employee satisfaction through a decreased workload. Methods: After identifying the problems caused by non-electronic prescriptions an automated system that allowed the issuance of time-specific prescriptions was developed. A new sig code was created that could be recognized by the Pharmacy electronic medical program, the label printer to group medications by administration times and the Automatic Tablet Counter(ATC) to count the grouped drugs accordingly. Result: With the new sig code, the practitioner became able to electronically select the times of drug administration while issuing the prescription. This 'time-specific prescription' can now be recognized by the pharmacy electronic medical program, the label printer and the ATC like any other prescription. Conclusion: The developed program started operating on September 2013. Although not all Parkinson's patients have been issued with the new electronic 'time-specific prescription', the overall dispensing process has become more streamlined and accurate. As the medical team continues to integrate the new system in their practice an additional decrease of the dispensing time is predicted. Future program upgrades and other new time-saving approaches are scheduled, which are expected to further increase the service quality of our outpatient pharmacy.

• Journal of Internet Computing and Services
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• v.11 no.5
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• pp.9-17
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• 2010

During the last decade, Internet protocol television(IPTV), broadcasting of multimedia services using well understood Internet technologies, is a fast spreading technology for distributing multimedia content to consumers. As IPTV services advance, an increasing user demand and tremendous content volume of multimedia content cause some difficulties in network resource management. In this paper, we propose an improved load balancing algorithm for video-on-demand(VoD) service. Unlike existing algorithms, the proposed algorithm considers user's behaviors for VoD service, and determines the most efficient allocation of VoD requests by estimating expected server load and expected user waiting time.

• Korean Management Science Review
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• v.28 no.3
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• pp.15-29
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• 2011

In this paper, we consider a system working at both primary service and secondary service. A server can switch between the primary service and the secondary service or it can be assigned to secondary service as a dedicated server. A service policy is characterized by the number of servers dedicated to the secondary service and a rule for switching the remaining servers between two services. The primary service system is modelled as a Markovian queueing system and the throughput is a function of the number of servers, buffer capacity, and service policy. And the secondary service system has a service level requirement strategically determined to perform the service assigned. There is a revenue obtained from throughput and costs due to servers and buffers. We study the problem of simultaneously determining the optimal total number of servers, buffers, and service policy to maximize profit of the system subject to both an expected customer waiting time constraint of the primary service and a service level constraint of the secondary service and develop an algorithm which can be successfully applied with the small number of computations.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.253-256
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• 2000

In general, Automated Storage/Retrieval Systems (AS/RS ) have racks of equal sized cells to utilize the concept of unit-load. Most of the techniques for the performance estimation of a unit-load AS/RS are a static model or computer simulation. Especially, their models were developed under assumption that the Storage/Retrieval (S/R) machine performs only single command (SC) or dual command (DC). In reality, defending on the operating policy and the status of the system at a particular time, the S/B machine performs a SC or a DC, or becomes .: idle. In order to resolve these weak points, we propose a stochastic model for the performance estimation of unit-load AS/RS by using a single-server queueing model. Expected numbers of waiting storage and retrieval commands are found

• Journal of the Korean Operations Research and Management Science Society
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• v.36 no.2
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• pp.51-65
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• 2011

We compared a CONWIP(constant work-in-process) system with a kanban system in a production line with constant processing times. Based on the observation that a WIP-controlled line production system such as CONWIP and kanban is equivalent to a m-node tandem queue with finite buffer, we applied a max-plus algebra based solution method for the tandem queue to evaluate the performance of two systems. Numerical examples with 6 workstations were used to demonstrate the proposed analysis. The numerical results support the previous studies that CONWIP outperforms kanban in terms of expected waiting time and WIP. Unlike the kanban case, sequencing workstations in a CONWIP does not affect the performance of the system.

• Journal of the Korean Operations Research and Management Science Society
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• v.4 no.1
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• pp.51-67
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• 1979

This paper considers the problem of determining an optimal dynamic operating policy for a two-stage tandem queueing service system in which the service facilities (or stages) can be operated at more than one service rate. At each period of the system's operation, the system manager must specify which of the available service rates is to be employed at each stage. The cost structure includes an operating cost for running each stage and a service facility profit earned when a service completion occurs at Stage 2. We assume that the system has a finite waiting capacity in front of each station and each customer requires two services which must be done in sequence, that is, customers must pass through Stage 1 and Stage 2 in that order. Processing must be in the order of arrival at each station. The objective is to minimize the total discounted expected cost in a two-stage tandem queueing service system, which we formulate as a Discrete-Time Markov Decision Process. We present analytical and numerical results that specify the form of the optimal dynamic operating policy for a two-stage tandem queueing service system.

• Management Science and Financial Engineering
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• v.15 no.2
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• pp.23-52
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• 2009

This study compares the cycle times of handling operations of yard cranes under different sequencing rules. An operation cycle was divided into several elementary movements and formulas for the expectation and the variance of each elementary movement were analytically derived. The expected waiting time of trucks was estimated based on the given arrival rate of trucks. The previous studies focused on developing a method to make an efficient schedule of operations for yard cranes. This paper introduces several sequencing rules, such as first-come-first-served, unidirectional travel, and Z pick travel rules. In addition, a formula for estimating the cycle times of yard cranes under each sequencing rule is derived, and the performance under the different sequencing rules are compared with each other.