• Journal of Korea Society of Industrial Information Systems
• /
• v.29 no.1
• /
• pp.63-76
• /
• 2024

In this study, we analyzed queue length and sojourn time of discrete-time BMAP/G/1 queues under the workload control. Group customers (packets) with correlations arrive at the system following a discrete-time Markovian arrival process. The server starts busy period when the total service time of the arrived customers exceeds a predetermined workload threshold D and serves customers until the system is empty. From the analysis of workload and waiting time, distributions of queue length at the departure epoch and arbitrary time epoch and system sojourn time are derived. We also derived the mean value as a performance measure. Through numerical examples, we confirmed that we can obtain results represented by complex forms of equations, and we verified the validity of the theoretical values by comparing them with simulation results. From the results, we can obtain key performance measures of complex systems that operate similarly in various industrial fields and to analyze various optimization problems.

• Journal of Korean Society of Environmental Engineers
• /
• v.22 no.6
• /
• pp.1149-1158
• /
• 2000

A radioisotope tracer experiment was carried out in the submerged fixed bioreactor of a dye wastewater treatment facility to evaluate the flow behaviors in the 6 compartments of the reactor and to find any possible factors which may affect to the efficiency of the process. Approximately 20mCi of $^{131}I$ was injected into the system as a tracer and 8 radiation detectors were placed in the 6 compartments and at the inlet and the outlet of the system to measure the change of the tracer concentration with time. Using the Perfect Mixers in Series Model the measured data were analyzed to calculate the mean residence time and the characteristic parameters of the flow in the system. The mean residence time of the system was calculated as 17 hours which is 76% of the designed MRT(22.3hr). Among the 6 compartments, the first compartment doesn't show the characteristic of perfect mixer, whereas, the other 5 compartments are working as perfect mixers. The output response of the first compartment is fit well with the simulated output of a model which consists of a perfect mixer with an exchange volume. It indicates that a quarter of the tank volume is working as a dead volume or an exchange volume. From the measured residence time distributions in each compartment, the appropriate sampling times after the change of operational condition of the electron beam accelerator were evaluated.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.14 no.2
• /
• pp.14-20
• /
• 2005

This paper describes a dwell time calculation algorithm for polishing tool path generation in the small toot polishing process of the axis-symmetrical lens. Generally dwell time control in the polishing machines means that small polishing tool stays for a dwell time at the specific surface position to get the expected polishing depth. Polishing depth distribution on an aspherical lens surface consists of the superposition of the local polishing depth at the each dwell position. Therefore, tool path generation needs each dwell time together with tool positioning data during the polishing tool movements on the aspherical lens surface. The linear algebraic equation of removal depth removal matrix and dwell time is formulated. Parametric effects such as the dwell d interval are simulated to validate the dwell time calculation algorithm.

• Proceedings of the KOR-KST Conference
• /
• 2007.02a
• /
• pp.141-150
• /
• 2007

• Journal of Korea Society of Industrial Information Systems
• /
• v.22 no.1
• /
• pp.23-32
• /
• 2017

In this paper, We suggest a unified approach for the analysis of discrete-time MAP/G/1 queueing system. Many researches on the D-MAP/G/1 queue have been used different approach to analyze system queue length and waiting time for the same system. Therefore, a unified framework for analyzing a system is necessary from a viewpoint of system design and management. We first derived steady-state workload distribution, and then waiting time and sojourn time are derived by the result of workload analysis. Finally, system queue length distribution is derived with generating function from the sojourn time distribution.

• Journal of KIISE:Software and Applications
• /
• v.26 no.11
• /
• pp.1288-1297
• /
• 1999

오늘날 많은 워크플로우 응용들은 마감 시간과 같은 시간 제약 조건들의 효율적인 관리를 요구하고 있다. 이러한 시간 제약성 워크플로우의 가장 중요한 목적들 중의 하나는 마감 시간을 만족하는 워크플로우 인스턴스의 수를 최대화하는 것이다. 시간 제약성 워크플로우 처리의 성능을 개선하기 위해서는 효과적인 액티비티들의 마감 시간 할당 방법이 요구된다. 이에 본 논문에서는 액티비티의 체재 시간과 워크플로우 제어 구조들의 특성을 고려하여 효과적인 마감 시간 할당 방법인 PST를 제안한다. PST는 기존의 방법들과 달리 워크플로우 제어 흐름을 분석하여 액티비티의 마감 시간을 할당하기 때문에 과부하에서도 높은 성능을 지원할 수 있다. 부가적으로 기존의 방법들과 성능 평가를 통해 본 논문에서 제안된 방법의 효용성을 검증한다.Abstract Nowadays, many workflow applications are requiring efficient time management such as deadline. With time-constrained workflows, one of the most important goals is to maximize the number of workflow instances that satisfy the deadline. In this regard, effective deadline assignment mechanisms should be developed to achieve high performance of time-constrained workflow processing. We propose in this paper our novel deadline assignment method called PST based on both an activity's sojourn time and the characteristics of workflow control structures. Because the method allocates the deadline to activities from analyzing the control flow of workflow, it can support good and stable workflow performance even under the high workload. In addition, we validate the usefulness of our proposed method through various experiments.

• Journal of Korea Society of Industrial Information Systems
• /
• v.29 no.2
• /
• pp.69-80
• /
• 2024

In this paper, we studied a discrete-time queuing system that operates under a mixed situation of D-policy and T-policy, one of the representative server control policies in queuing theory. A single server serves customers arriving by Bernoulli arrival process on a first-in, first-out basis(FIFO). If there are no customers to serve in the system, the server goes on vacation and returns, until the total service time (i.e., total amount of workload) of waiting customers exceeds predetermined workload threshold D. The operation of the system covered in this study can be used to model the efficient resource utilization of mobile devices using secondary batteries. In addition, it is significant in that the steady state waiting time and system sojourn time of the queuing system under a flexible mixed control policy were derived within a unified framework.

• Proceedings of the ESK Conference
• /
• 1998.04a
• /
• pp.131-136
• /
• 1998

2개의 simulated된 잠수 실험 즉, 심도 19 ATA와 24 ATA의 고압 Heliox 환경하에서, 4명의 다이 버를 대상으로 하여연 188일간 매일 23:00부터 익일7:00시 사이에 각 다이버에대해서 표준적인 polysomnography를 기록했다. 2개의 잠수조건 하에서 양 실험 모두 해저에서 체재하는 동안 의 밤과 감압하는 동안의 밤 동안에는 총수면시간 (Total Sleep Time)의 단축, 수면효율(Sleep Efficiency)의 감소, 입면잠시(Sleep Latency)의 연장, 중도각성회수 (Number of Awakeningss) 와 감소를 보였지만, 어느쪽도 뚜려한 변화가 있었다라고는 할 수 없었다. 24 ATA 잠수조건에서 의 해저에서 체재하는 동안의 밤과 감압하는 동안의 밤 동안에서는 19 ATA 잠수조건에 비해서 4 단계수면(stage 4 sleep )만 유의한 감소를 보였다. 2개의잠수조건 모두 잠수기간 중에 있어서 는 각성하기 쉬운 상황이었으며, 기본적인 수면패턴에 있어서는 큰 변화는 보이지 않았다.

• Journal of Navigation and Port Research
• /
• v.30 no.5 s.111
• /
• pp.389-396
• /
• 2006

With the recent port environment, the integration of the separated berth is being actively progressed and the necessity of integration has been strengthening. Therefore, the application of existing gates have to review in order to reduce the truck turnaround time and to distribute the truck traffic volume in port container terminal. This paper analyzed the operation impact both the integrated gate and the separated gates. As the result of the analysis, this study suggests the separated gate system as an efficient design for gate operation considering integration of two individual berth.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2005.10a
• /
• pp.125-131
• /
• 2005

Gate operations are very important as they are the starting point for export containers and the end point for import containers as far as checking and control exercised by terminal operators are concerned. The objective of this paper is to propose the design of separated gate system in order to reduce the truck turnaround time and to distribute the truck traffic volume in port container terminal. Because of a lot of container load and unload within short term, many trucks have to pass the gate at a time. This study suggests the separated gate system as an efficient design for gate operation considering integration of two individual berth.