• Journal of the Korean GEO-environmental Society
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• v.25 no.4
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• pp.13-20
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• 2024

In this paper, a parallel analysis algorithm for Smoothed Particle Hydrodynamics (SPH), one of the numerical methods for fluidic materials, is introduced. SPH, which is a meshless method, can represent the behavior of a continuum using a particle-based approach, but it demands substantial computational resources. Therefore, parallel analysis algorithms are essential for SPH simulations. The domain decomposition algorithm, which divides the computational domain into partitions to be independently analyzed, is the most representative method among parallel analysis algorithms. In Discrete Element Method (DEM) and Molecular Dynamics (MD), the Cartesian coordinate-based domain decomposition method is popularly used because it offers advantages in quickly and conveniently accessing particle positions. However, in SPH, it is important to share particle information among partitioned domains because SPH particles are defined based on information from nearby particles within the smoothing length. Additionally, maintaining CPU load balance is crucial. In this study, a highly parallel efficient algorithm is proposed to dynamically minimize the size of orthogonal domain partitions to prevent excess CPU utilization. The efficiency of the proposed method was validated through numerical analysis models. The parallel efficiency of the proposed method is evaluated for up to 30 CPUs for fluidic models, achieving 90% parallel efficiency for up to 28 physical cores.

• Journal of Bio-Environment Control
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• v.23 no.3
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• pp.205-211
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• 2014

This study aimed to examine the effect of different fruit-loads on fruit yield, quality, and plant growth of 'Seolhyang' strawberry. Fruit loads were adjusted from the first to the fourth flower cluster so that the number of fruits became 20, 25, and 30, and non-flower thinning of some was made. The more the number of fruits per plant was, the greater the total yield obtained, but marketable yield decreased and non-marketable yield increased. Compared to the treatment whose fruit load was adjusted, the control with non-flower thinning had more fruit yield in the first and second flower clusters but tended to have less fruit yield in the third and fourth flower clusters. The lower the fruit load was, the more soluble solids content of fruits increased. The lower the fruit load of a flower cluster was, the faster its harvest time reached. Harvest of fruit load of 20 was faster by 10 days in the second and fourth flower clusters relative to the control. On November 24, 2012, flowering thinning of the first flower cluster was made. On March 7, 2013, fruit dry weight of the second flower cluster was most heavy in the control. Dry weight of roots decreased in the control and the fruit load of 30 compared to November 24. On April 9, fruit dry weight of the third flower cluster did not have significant difference according to fruit load, however the more the fruit load was, the smaller dry weight of leaf, root, and crown became, which were vegetative organs. On May 12, the more the fruit load, the smaller leaf area and dry weight of vegetative organs and differences from varying fruit-loads became considerable in later period of growth. Appropriate fruit load of 'Seolhyang' strawberry were from 20 to 25. Maintaining balance between vegetative and fruit growth by adjusting fruit load is very important for stable fruit production.

• International Journal of Computer Science & Network Security
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• v.21 no.11
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• pp.345-353
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• 2021

Cloud computing represent a new era of computing that's forms through the combination of service-oriented architecture (SOA), Internet and grid computing with virtualization technology. Virtualization is a concept through which every cloud is enable to provide on-demand services to the users. Most IT service provider adopt cloud based services for their users to meet the high demand of computation, as it is most flexible, reliable and scalable technology. Energy based performance tradeoff become the main challenge in cloud computing, as its acceptance and popularity increases day by day. Cloud data centers required a huge amount of power supply to the virtualization of servers for maintain on- demand high computing. High power demand increase the energy cost of service providers as well as it also harm the environment through the emission of CO₂. An optimization of cloud computing based on energy-performance tradeoff is required to obtain the balance between energy saving and QoS (quality of services) policies of cloud. A study about power usage of resources in cloud data centers based on workload assign to them, says that an idle server consume near about 50% of its peak utilization power [1]. Therefore, more number of underutilized servers in any cloud data center is responsible to reduce the energy performance tradeoff. To handle this issue, a lots of research proposed as energy efficient algorithms for minimize the consumption of energy and also maintain the SLA (service level agreement) at a satisfactory level. VM (virtual machine) consolidation is one such technique that ensured about the balance of energy based SLA. In the scope of this paper, we explore reinforcement with fuzzy logic (RFL) for VM consolidation to achieve energy based SLA. In this proposed RFL based active VM consolidation, the primary objective is to manage physical server (PS) nodes in order to avoid over-utilized and under-utilized, and to optimize the placement of VMs. A dynamic threshold (based on RFL) is proposed for over-utilized PS detection. For over-utilized PS, a VM selection policy based on fuzzy logic is proposed, which selects VM for migration to maintain the balance of SLA. Additionally, it incorporate VM placement policy through categorization of non-overutilized servers as- balanced, under-utilized and critical. CloudSim toolkit is used to simulate the proposed work on real-world work load traces of CoMon Project define by PlanetLab. Simulation results shows that the proposed policies is most energy efficient compared to others in terms of reduction in both electricity usage and SLA violation.

• The KIPS Transactions:PartD
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• v.9D no.5
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• pp.755-768
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• 2002

We investigate the effect of the data skew of join attributes on the performance of a pipelined multi-way hash join method, and propose two new hash join methods with load balancing capabilities. The first proposed method allocates buckets statically by round-robin fashion, and the second one allocates buckets adaptively via a frequency distribution. Using hash-based joins, multiple joins can be pipelined so that the early results from a join, before the whole join is completed, are sent to the next join processing without staying on disks. Unless the pipelining execution of multiple hash joins includes some load balancing mechanisms, the skew effect can severely deteriorate system performance. In this paper, we derive an execution model of the pipeline segment and a cost model, and develop a simulator for the study. As shown by our simulation with a wide range of parameters, join selectivities and sizes of relations deteriorate the system performance as the degree of data skew is larger. But the proposed method using a large number of buckets and a tuning technique can offer substantial robustness against a wide range of skew conditions.

• Ocean Systems Engineering
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• v.6 no.1
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• pp.61-97
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• 2016

This is the second of two papers on the 3D numerical modeling of nearshore hydro- and morphodynamics. In Part I, the focus was on surf and swash zone hydrodynamics in the cross-shore and longshore directions. Here, we consider nearshore processes with an emphasis on the effects of oceanic forcing and beach characteristics on sediment transport in the cross- and longshore directions, as well as on foreshore bathymetry changes. The Delft3D and XBeach models were used with four turbulence closures (viz., ${\kappa}-{\varepsilon}$, ${\kappa}-L$, ATM and H-LES) to solve the 3D Navier-Stokes equations for incompressible flow as well as the beach morphology. The sediment transport module simulates both bed load and suspended load transport of non-cohesive sediments. Twenty sets of numerical experiments combining nine control parameters under a range of bed characteristics and incident wave and tidal conditions were simulated. For each case, the general morphological response in shore-normal and shore-parallel directions was presented. Numerical results showed that the ${\kappa}-{\varepsilon}$ and H-LES closure models yield similar results that are in better agreement with existing morphodynamic observations than the results of the other turbulence models. The simulations showed that wave forcing drives a sediment circulation pattern that results in bar and berm formation. However, together with wave forcing, tides modulate the predicted nearshore sediment dynamics. The combination of tides and wave action has a notable effect on longshore suspended sediment transport fluxes, relative to wave action alone. The model's ability to predict sediment transport under propagation of obliquely incident wave conditions underscores its potential for understanding the evolution of beach morphology at field scale. For example, the results of the model confirmed that the wave characteristics have a considerable effect on the cumulative erosion/deposition, cross-shore distribution of longshore sediment transport and transport rate across and along the beach face. In addition, for the same type of oceanic forcing, the beach morphology exhibits different erosive characteristics depending on grain size (e.g., foreshore profile evolution is erosive or accretive on fine or coarse sand beaches, respectively). Decreasing wave height increases the proportion of onshore to offshore fluxes, almost reaching a neutral net balance. The sediment movement increases with wave height, which is the dominant factor controlling the beach face shape.

• The KIPS Transactions:PartA
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• v.11A no.5
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• pp.355-364
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• 2004

These days, various clustering technologies have been adopted to construct web sites. High performance hardware switches have good performance, but have disadvantage of high cost for constructing small and middle-sized web sites. Now a days, many sites have been constructed with the LVS (Linux Virtual Server), which is free of charge and has good performance. Having a centralized load balancing with one front-end, the LVS causes a bottleneck when it receives all at once. In the paper, we suggest a way to remove the LVS bottleneck by providing multiple front-ends. In this architecture, all of cluster nodes act as both a front-end and a back-end. When the load of a node receiving requests is not large enough, the node responds to the client directly. When the load of a node is large enough, the node send the request to a node which is selected by a scheduling algorithm. The scheduling algorithm is discussed to balance loads between servers. While single front-end cluster raises the throughput curvedly, the multiple front-end cluster raises the throughput linearly.

• Journal of KIISE:Databases
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• v.30 no.6
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• pp.629-640
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• 2003

A shared disk (SD) cluster couples multiple nodes for high performance transaction processing, and all the coupled nodes share a common database at the disk level. In the SD cluster, a transaction routing corresponds to select a node for an incoming transaction to be executed. An affinity-based routing can increase local buffer hit ratio of each node by clustering transactions referencing similar data to be executed on the same node. However, the affinity-based routing is very much non-adaptive to the changes in the system load, and thus a specific node will be overloaded if transactions in some class are congested. In this paper, we propose a dynamic transaction routing scheme that can achieve an optimal balance between affinity-based routing and dynamic load balancing of all the nodes in the SD cluster. The proposed scheme is novel in the sense that it can improve the system performance by increasing the local buffer hit ratio and reducing the buffer invalidation overhead.

• Korean Journal of Organic Agriculture
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• v.24 no.4
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• pp.869-879
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• 2016

The present study was conducted to evaluate the effects of dietary formulated feed additive on growth performance and carcass traits of Hanwoo steers. A formulated feed additive reported to reduce heat load in the rumen in our previous research was used (Cho et al., 2014). Total 32 herds of Hanwoo steers were assigned into two groups of control and treatment. Total mixed ration was provided as basal diet for cattle and 100 g of additive was supplemented on diet for treatment. Feeding trial was performed during 120 days before slaughter. For growth performance, 3 periods (0~90 days; 90~120 days; 0~120 days) were allotted and average daily gain, feed requirement and final body weight were determined. Loin meat between $12^{th}$ and $13^{th}$ rib was used for meat quality analysis after slaughtering. Only $1^{st}$ period showed significantly improved growth performance of treatment (P<0.05) and there were no significant difference in other periods. At $3^{rd}$ periods (overall), a trend of increased average daily gain was found at treatment (P=0.075). Carcass performance and quality did not show significant differences between treatment and control (P>0.05). In meat quality, treatment showed significant increment in all measured meat colors (P<0.05) and significantly less sharing force compared to the control (P<0.05). Although no significant difference in growth performance and carcass yield were found, remarkably improved economic status was detected in treatment group. In conclusion, it could be suggested that application of a formulated feed additive specialized in reduction of heat load in the rumen was able to increase economical balance through enhancing heat stress condition of ruminant and growth.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.64-70
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• 2018

Rollover is a major concern for vehicles with a higher center of gravity and for improving driving performance. This study investigates a tilting system to prevent rollover, which was successfully implemented for high-speed trains. It may be useful to apply the concept of the tilting system to a large truck such as a trailer. Even a small adjustment in the tilting angle can improve the driving stability during a steep turn. The equation of motion was derived from a dynamic model of the trailer with the tilting system. The balance of the centrifugal force and normal force determines the rollover critical speed for a given radius of the turn and load. To obtain a more conservative criterion, the rollover critical state was defined as the instant when any side wheel loses contact with the road. To actuate the tilting system, the optimal tilting angle must be calculated from the steering angle and the vehicle speed. Using a simplified model of a large truck, the effects of the tilting angle and load on the rollover critical speed were investigated.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.8
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• pp.17-25
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• 1998

Aluminum alloys have low density, relatively high strength and yield strength, good plasticity, good machinability, and high corrosion and acid resistance. Therefore, they are suitable for large containers for the food, chemical and other industries. Large containers are often bodies of revolution consisting of shell courses, stiffening rings, heads and other elements joined by annular welds. Larger containers have longer welds and require greater leak-tightness and higher weld mechanical properties. The LNG tank consists of aluminum plates with various sizes, so its construction should by divided by several sections. Moreover, each section has its own sub-section consisted of several aluminum plates. To guarantee the quality of huge LNG tank, therefore, the precise control of plate dimension should by urgently needed in conjunction with the appropriate selection of process parameters such as cutting speed, depth of cut, rotational speed and so on. In this paper, a manufacturing system was developed to implement automatic circular tracking in height direction and automatic circular interpolation in depth of cut direction. Also, the neural network based on the backpropagation algorithm was used to predict the cutting quality and motor load related with the life time of the developed system. It was revealed that the manufacturing system and the neural network could be effectively applied to the bevelling process and to predict the quality of machined area and the motor load.