• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.22 no.50
• /
• pp.161-170
• /
• 1999

This paper evaluates forty different dispatching rules with respect to twenty different performance measures of job shop scheduling under seven levels of workload imbalance. Computer simulation is used as a tool to determine rankings of the dispatching rules for a given workload imbalance. The experiments results show rankings of dispatching rules are different in the job shop with unbalanced machine workloads. As variations of workload imbalance increase from 7% to 78%, the performance of dispatching rules is gradually deteriorated in measure related to completion time and due date. These results guide scheduling practitioners not only to choosing dispatching rules but also to developing the model of facility investment for workload balance, when there are different levels of workload imbalance.

• Industrial Engineering and Management Systems
• /
• v.3 no.1
• /
• pp.52-58
• /
• 2004

This report examines the issue of designing an efficient production system by increasing several types of flexibility. Increasing manufacturing flexibility is a key strategy for efficiently improving market responsiveness in the face of uncertain market demand for final products. The manufacturing system comprises multiple plants, of which individual plants have multiple manufacturing lines that are designed to produce limited types of products in accordance with their size and materials. Imbalance in the workload occurs among plants as well as among manufacturing lines because of fluctuations in market demand for final products. Thereby, idleness of some manufacturing lines and longer lead times in some manufacturing lines occur as a result of the high workload. We clarify how these types of flexibility affect manufacturing performance by improving only one type of flexibility or by improving multiple types of flexibility simultaneously. The average lead time and the imbalance in workload are adopted as measures of manufacturing performance. Three types of manufacturing flexibility are interrelated: machine flexibility, routing flexibility, and process flexibility. Machine flexibility refers to the various types of operations that a machine can perform without requiring the prohibitive effort of switching from one order to another. Routing flexibility is the capability of processing a given set of part types using more than one line (alternative line) in the plant. Process flexibility results from being able to build different types of final products at the same plant.

• Journal of Information Processing Systems
• /
• v.16 no.1
• /
• pp.132-144
• /
• 2020

Cloud computing is an emerging technology based on the concept of enabling data access from anywhere, at any time, from any platform. The exponential growth of cloud users has resulted in the emergence of multiple issues, such as the workload imbalance between the virtual machines (VMs) of data centers in a cloud environment greatly impacting its overall performance. Our axis of research is the load balancing of a data center's VMs. It aims at reducing the degree of a load's imbalance between those VMs so that a better resource utilization will be provided, thus ensuring a greater quality of service. Our article focuses on two phases to balance the workload between the VMs. The first step will be the determination of the threshold of each VM before it can be considered overloaded. The second step will be a task allocation to the VMs by relying on an improved and faster version of the meta-heuristic "simulated annealing (SA)". We mainly focused on the acceptance probability of the SA, as, by modifying the content of the acceptance probability, we could ensure that the SA was able to offer a smart task distribution between the VMs in fewer loops than a classical usage of the SA.

• Journal of Broadcast Engineering
• /
• v.17 no.5
• /
• pp.742-755
• /
• 2012

In this paper, we propose a parallel deblocking algorithm to resolve workload imbalance when the deblocking filter of high efficiency video coding (HEVC) decoder is parallelized. In HEVC, the deblocking filter which is one of the in-loop filters conducts two-step filtering on vertical edges first and horizontal edges later. The deblocking filtering can be conducted with high-speed through data-level parallelism because there is no dependency between adjacent edges for deblocking filtering processes. However, workloads would be imbalanced among regions even though the same amount of data for each region is allocated, which causes performance loss of decoder parallelization. In this paper, we solve the problem for workload imbalance by predicting the complexity of deblocking filtering with coding unit (CU) depth information at a coding tree block (CTB) and by allocating the same amount of workload to each core. Experimental results show that the proposed method achieves average time saving (ATS) by 64.3%, compared to single core-based deblocking filtering and also achieves ATS by 6.7% on average and 13.5% on maximum, compared to the conventional uniform data-level parallelism.

• Journal of Korean Institute of Industrial Engineers
• /
• v.29 no.3
• /
• pp.213-221
• /
• 2003

In this paper, we consider a multi-objective part-machine grouping problem, in which part types have several alternative part routings and each part routing has a machining sequence. This problem is characterized as optimally determining part type sets and its corresponding machine cells such that the sum of inter-cell part movements and the sum of machine workload imbalances are simultaneously minimized. Due to the complexity of the problem, a two-stage heuristic algorithm is proposed, and experiments are shown to verify the effectiveness of the algorithm.

• Korea Journal of Hospital Management
• /
• v.25 no.3
• /
• pp.1-13
• /
• 2020

Purpose: This study was conducted to identify the conceptual definition and attributes of 'Taeoom' (or workplace bullying) inflicted to newly employed nurses in Korea. Method: Walker & Avant(2011)'s eight-stage process was used to perform a conceptual analysis of 'Taeoom'. Literature review of 40 studies published between Jan. 2009 and March 2018 published in Korea was followed by the in-depth interview with nine newly employed hospital nurses and the ex-post review of results by nursing experts. Findings: 'Taeoom' was associated with five attributes: (1) bullying for no reason, (2) peer rejection for no reason, (3) decreased physical function and psychological withdrawal, and (4) verbal abuse, defamation and nagging, (5) impotent feeling due to power imbalance. Four antecedents found in this study include offensive action, distrust, power imbalance, and undue workload exceeding capacity. As consequences of Taeoom, negative physical and psychological symptoms and turnover intention were increased while nursing performance was decreased. Conclusion: This study suggests the need for more qualitative researches with more comprehensive approach on Taeoom and the development of effective program to improve the organizational culture in nursing field. This study is significant in that it provides a qualitative but comparative review on the attributes, antecedents and consequences of Taeoom through literature review accompanied by focus group interview and expert review.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.30 no.3
• /
• pp.41-54
• /
• 2005

In this paper, we consider a multi-objective machine cell formation problem. This problem Is characterized as determining part route families and machine cells such that total sum of inter-ceil part movements and maximum machine workload imbalance are simultaneously minimized. Together with the objective function, alternative part routes and the machine sequences of part routes are considered In grouping Part route families. Due to the complexity of the problem, a two-phase heuristic algorithm is proposed. And we developed an n-stage look-ahead heuristic algorithm that generalizes the roll-out algorithm. Computational experiments were conducted to verify the performance of the algorithm.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.11 no.12
• /
• pp.5694-5711
• /
• 2017

The technology of cloud computing is growing very quickly, thus it is required to manage the process of resource allocation. In this paper, load balancing algorithm based on honey bee behavior (LBA_HB) is proposed. Its main goal is distribute workload of multiple network links in the way that avoid underutilization and over utilization of the resources. This can be achieved by allocating the incoming task to a virtual machine (VM) which meets two conditions; number of tasks currently processing by this VM is less than number of tasks currently processing by other VMs and the deviation of this VM processing time from average processing time of all VMs is less than a threshold value. The proposed algorithm is compared with different scheduling algorithms; honey bee, ant colony, modified throttled and round robin algorithms. The results of experiments show the efficiency of the proposed algorithm in terms of execution time, response time, makespan, standard deviation of load, and degree of imbalance.

• Journal of Broadcast Engineering
• /
• v.17 no.3
• /
• pp.503-518
• /
• 2012

In this paper, we propose a complexity-based parallelization method of the sample adaptive offset (SAO) algorithm which is one of HEVC in-loop filters. The SAO algorithm can be regarded as region-based process and the regions are obtained and represented with a quad-tree scheme. A offset to minimize a reconstruction error is sent for each partitioned region. The SAO of the HEVC can be parallelized in data-level. However, because the sizes and complexities of the SAO regions are not regular, workload imbalance occurs with multi-core platform. In this paper, we propose a LCU-based SAO algorithm and a complexity prediction algorithm for each LCU. With the proposed complexity-based LCU processing, we found that the proposed algorithm is faster than the sequential implementation by a factor of 2.38 times. In addition, the proposed algorithm is faster than regular parallel implementation SAO by 21%.

• Journal of Korea Multimedia Society
• /
• v.11 no.7
• /
• pp.914-927
• /
• 2008

Grid database management systems are used for large data processing, high availability and data integration in grid computing. Furthermore the grid database management systems are in the use of manipulating the queries that are sent to distributed nodes for efficient query processing. However, when the query processing is concentrated in a random node, it will be occurred with imbalance workload and decreased query processing. In this paper we propose a load balancing method for query processing based on cache Management in grid databases. This proposed method focuses on managing a cache in nodes by cache manager. The cache manager connects a node to area group and then the cache manager maintains a cached meta information in node. A node is used for caching the efficient meta information which is propagated to other node using cache manager. The workload of node is distributed by using caching meta information of node. This paper shows that there is an obvious improvement compared with existing methods, through adopting the proposed algorithm.