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시험시간과 오류수정개수를 고려한 소프트웨어 출시 시점결정
유영관,Yoo, Young Kwan 한국벤처창업학회 2012 벤처창업연구 Vol.7 No.4
본 논문에서는 시험시간과 오류의 수정개수를 동시에 고려하는 소프트웨어 출시 모형을 제시한다. 소프트웨어의 시험기간은 정해진 시험시간이나 오류수정개수 중 먼저 도래하는 시간까지 지속된다. 고려되는 비용은 시험기간 중의 오류수정비용과 출시 지연비용, 그리고 시험기간 경과 후의 운용 중 발생하는 오류수정비용으로 구성된다. 생명주기는 특별한 제한이 없고, 오류의 검출과정은 비제차 포아송과정을 따른다고 가정한다. 총비용함수가 도출되며 이전의 출시방안들은 제시된 모형의 특별한 경우임을 보인다. In this paper, a software policy considering testing time and the number of errors corrected is presented. The software is tested until a specified testing time or the time to a specified number of errors are corrected, whichever comes first. The model includes the cost of error correction and software testing during the testing time, and the cost of error correction during operation. It is assumed that the length of software life cycle has no bounds, and the error correction follows an non-homogeneous Poisson process. An expression for the total cost under the policy is derived. It is shown that the model includes the previous models as special cases.
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.
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.
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 Random Use Durations before Replacement
유영관 한국경영공학회 2005 한국경영공학회지 Vol.10 No.3
This paper presents an another periodic replacement policy under minimal repair when a system undergoes random durations of operations. The system is put in operation and then idle for some time. The time durations of each use(operation) are random variables. During the idle times, system experiences no aging. Under the proposed policy, system is replaced after a number of use durations elapses. The failures during use durations are minimally repaired instantaneously. The cost rate expressions under the policy is derived for exponential use durations and Weibull failure distribution. It is shown that under some conditions there exists a finite optimum value of the control variable. Numerical examples are presented to compare the presented model with the previous model.