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A SOFTWARE RELEASE POLICY WITH ERROR COUNT AND TESTING TIME
유영관 한국경영공학회 2015 한국경영공학회지 Vol.20 No.3
This paper presents a model to determine the software release time with two decision criteria, the major errors corrected and the testing time elapsed. Under the policy, the software is tested until a predetermined number of major errors are corrected or some length of testing time elapsed, whichever comes first. The errors in software are classified into two types, major or minor errors. The expected total lifecycle cost of correcting errors during test and after release is derived based on a software reliability growth model. The optimum values of policy variables that minimize the total cost are explored.
Optimal Maintenance and Spare Provisioning for a Unit with Random Working Time
유영관 대한설비관리학회 2019 대한설비관리학회지 Vol.24 No.4
This paper deals with a joint optimizing problem of maintenance and spare provisioning for a unit with random working time. The unit operates in a random cyclic manner: the unit executes jobs successively, and the job has a variable working cycle. A maintenance policy is applied as follows. The unit is preventively replaced by a new one at a predetermined time or at the end of working time, whichever comes first. When the unit fails before preventive replacement, it is immediately replaced by a new one. An inventory policy for the unit is applied as follows: Some quantity is ordered for spare provisioning and used when the unit fails or preventively replaced. The spares are immediately replenished when the stock comes to zero. The cost rates per unit time under the joint maintenance and inventory policy is obtained as a function of preventive maintenance time and ordering quantity. It is shown that under some conditions there exist finite optimal values of the policy variables. Numerical examples are provided to demonstrate the results.
Periodic Replacement of a System Subject to Shocks under Random Operating Horizon
유영관,Yoo, Youngkwan Korea Safety ManagementScience 2021 안전경영과학회지 Vol.23 No.4
This paper presents a periodic replacement policy for a system subject to shocks when the system is operating for a finite random horizon. The system is subject to shocks during operation, and each shock causes downgrading of the system performance and makes it more expensive to run by the additional running cost. Shocks arrive according to a nonhomogeneous or a renewal process, and we develop periodic replacement policies under a finite random operating horizon. The optimum periodic replacement interval which minimizes the total operating cost during the horizon is found. Numerical examples are presented to demonstrate the results.
패키지 소프트웨어를 위한 품질인증 방법의 설계에 관한 연구
유영관,이종무 대한안전경영과학회 2002 대한안전경영과학회지 Vol.4 No.1
The certification of software products can provide a greater level of acceptance and feeling of security to customers of these products. This paper presents a certification method for the quality of package software. First of all, the evaluation criteria are derived from ISO/IEC 9126 and 12119 standards, and then the evaluation module are designed considering the measurement scale type. The results can be applied to construct the certification scheme of software product quality for the commercial purpose.
Optimal Number of Failures before Group Replacement under Minimal Repair
유영관 대한안전경영과학회 2004 대한안전경영과학회지 Vol.6 No.1
In this paper, a group replacement policy based on a failure count is analysed. For a group of identical repairable units, a maintenance policy is performed with two phase considerations: a repair interval phase and a waiting interval phase. Each unit undergoes minimal repair at failure during the repair interval. Beyond the interval, no repair is made until a number of failures. The expected cost rate expressions under the policy is derived. A method to obtain the optimal values of decision variables are explored. Numerical examples are given to demonstrate the results.
Optimal number of failures before group replacement under minder repair
유영관 대한안전경영과학회 2004 대한안전경영과학회지 Vol.6 No.1
In this paper, a group replacement policy based on a failure count is analysed. For a group of identical repairable units, a maintenance policy is performed with two phase considerations: a repair interval phase and a waiting interval phase. Each unit undergoes minimal repair at failure during the repair interval. Beyond the interval, no repair is made until a number of failures. The expected cost rate expressions under the policy is derived. A method to obtain the optimal values of decision variables are explored. Numerical examples are given to demonstrate the results.