• The Journal of the Korea Contents Association
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• v.18 no.4
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• pp.178-185
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• 2018

Recently, demands for computer systems with multicore CPUs and high-performance flash-based storage devices (i.e., flash SSD) have rapidly grown in cloud computing, surer-computing, and enterprise storage/database systems. Journaling file systems running on high-performance systems do not exploit the full I/O bandwidth of high-performance SSDs. In this article, we evaluate and analyze the performance of the Linux EXT4 file system with high-performance SSDs and multicore CPUs. The system used in this study has 72 cores and Intel NVMe SSD, and the flash SSD has performance up to 2800/1900 MB/s for sequential read/write operations. Our experimental results show that checkpointing in the EXT4 file system is a major overhead. Furthermore, we optimize the checkpointing procedure and our optimized EXT4 file system shows up to 92% better performance than the original EXT4 file system.

• The Transactions of the Korea Information Processing Society
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• v.7 no.8S
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• pp.2608-2619
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• 2000

This paper proposes the Handover Scheme for the mobile and describes the result of the performance analysis. In the conventional scheme of handover request, the withdrawal of terminal may occur because handover request is performed based on fixed signal level without considering network load and terminal mobility. The proposed scheme offers the minimization of withdrawal and handover blocking probability by means of the handover request of terminal based on the network load and terminal mobility. Conventional handover scheme has the sequential procedure that network performs resource check and path rerouting on the handover by MT(Mobile Terminal). Proposed handover scheme pre-processes the resource check before the handover request by predicting the handover request timo so that handover latency can be reduced. Moreover, path optimization is executed after the completion of handover in order to reduce handover latency. The rdduction of handover latency prevents the dropping of service by minimizing backward handover blocking. In summary, we propose the prediction of handover request time and decision method based on terminal, validating the performance of proposed scheme considering various cases of simulation.

• Journal of Korean Society for Quality Management
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• v.41 no.1
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• pp.109-118
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• 2013

Purpose: Given the several proper models for given mixture components-process variables experimental data, we propose a strategy to find the optimal condition in which the performance of the responses is well-behaved under those models. Methods: Given the mixture experimental data with process variables, first we choose the reasonable starting models among the class of admissible product models based on the model selection criteria and then, search for the candidate models that are the subset models of the starting model by the sequential variable selection method or all possible regressions procedure. Good candidate models are screened by the evaluation of model selection criteria and checking the residual plots for the validity of the model assumption. Results: We propose a strategy to find the optimal condition in which the performance of the responses is well-behaved under those good candidate models by adopting the optimization methods developed in multiple responses surface methodology. Conclusion: A strategy is proposed to find the optimal condition in which the performance of the responses is well-behaved under those proper combined models. This strategy to find the optimal condition is illustrated with the example in this paper.

• Journal of Microbiology and Biotechnology
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• v.30 no.11
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• pp.1785-1791
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• 2020

In a previous study, the sequential optimization and regulation of environmental parameters using the PhotoBiobox were demonstrated with high-throughput screening tests. In this study, we estimated changes in the biovolume-based composition of a polyculture built in vitro and composed of three algal strains: Chlorella sp., Scenedesmus sp., and Parachlorella sp. We performed this work using the PhotoBiobox under different temperatures (10-36℃) and light intensities (50-700 μmol m^-2 s^-1) in air and in 5% CO₂. In 5% CO₂, Chlorella sp. exhibited better adaptation to high temperatures than in air conditions. Pearson's correlation analysis showed that the composition of Parachlorella sp. was highly related to temperature whereas Chlorella sp. and Scenedesmus sp. showed negative correlations in both air and 5% CO₂. Furthermore, light intensity slightly affected the composition of Scenedesmus sp., whereas no significant effect was observed in other species. Based on these results, it is speculated that temperature is an important factor in influencing changes in algal polyculture community structure (PCS). These results further confirm that the PhotoBiobox is a convenient and available tool for performance of lab-scale experiments on PCS changes. The application of the PhotoBiobox in PCS studies will provide new insight into polyculture-based ecology.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.2
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• pp.287-295
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• 2010

In this paper, we introduce a novel approach to optimization algorithm which is a distributed Mean field Genetic algorithm (MGA) implemented in MPI(Message Passing Interface) environments. Distributed MGA is a hybrid algorithm of Mean Field Annealing(MFA) and Simulated annealing-like Genetic Algorithm(SGA). The proposed distributed MGA combines the benefit of rapid convergence property of MFA and the effective genetic operations of SGA. The proposed distributed MGA is applied to the channel routing problem, which is an important issue in the automatic layout design of VLSI circuits. Our experimental results show that the composition of heuristic methods improves the performance over GA alone in terms of mean execution time. It is also proved that the proposed distributed algorithm maintains the convergence properties of sequential algorithm while it achieves almost linear speedup as the problem size increases.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.7
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• pp.943-948
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• 2018

In this paper, we propose a hybrid approach of combining $A^*$ and Genetic algorithm in the path search problem. In $A^*$, the cost from a start node to the intermediate node is optimized in principle but the path from that intermediate node to the goal node is generated and tested based on the cumulated cost and the next node in a priority queue is chosen to be tested. In that process, we adopt the genetic algorithm principle in that the group of nodes to generate the next node from an intermediate node is tested by its fitness function. Top two nodes are selected to use crossover or mutation operation to generate the next generation. If generated nodes are qualified, those nodes are inserted to the priority queue. The proposed method is compared with the original sequential selection and the random selection of the next searching path in $A^*$ algorithm and the result verifies the superiority of the proposed method.

• Journal of Soil and Groundwater Environment
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• v.20 no.2
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• pp.47-54
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• 2015

The objective of this study was to optimize the experimental conditions for bioleaching of arsenic (As) using Herbaspirillum sp. GW103 and to understand the interaction between bacteria and As during bioleaching. Five variables, temperature, time, CaCO₃, coconut oil cake, and shaking rate, were optimized using response surface methodology (RSM) based Box-Behnken design (BBD). Maximum (73.2%) bioleaching of As was observed at 30℃, 60 h incubation, 1.75% CaCO₃, 3% coconut oil cake, and 140 rpm. Sequential extraction of bioleached soil revealed that the isolate Herbaspirillum sp. GW103 significantly reduced 28.6% of water soluble fraction and increased 38.8% of the carbonate fraction. The results of the study indicate that the diazotrophic bacteria Herbaspirillum sp. could be used for bioleaching As from mine soil.

• Journal of Korean Society on Water Environment
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• v.37 no.6
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• pp.433-441
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• 2021

The aim of this study was to optimize the ozonation and ceramic membrane integrated process for greywater reclamation. The integrated process is a repeated sequential process of filtration and backwash with the same ceramic membrane. Also, this study used ozone and oxygen gas for the backwashing process to compare backwashing efficiency. The study results revealed that the optimum filtration and backwash time for the process was 10 minutes each when comparing the filtrate flow and membrane recovery rate. The integrated process was operated at three different operating conditions with i) 10 minutes for filtration and 10 minutes for ozonation, ii) 10 minutes for filtration and 10 minute for oxygen aeration, and iii) continuous filtration without any aeration for synthetic greywater. The integrated process with ozone backwashing could produce 0.55 L/min of filtrate with an average of 18.42% permeability recovery, while the oxygen backwashing produced 0.47 L/min and 6.26%, respectively. And without any backwashing, the integrated process could produce 0.29 L/min. This shows that the ozone backwash process is capable of periodically recovering from membrane fouling. The resistance of the fouled membrane was approximately 34.4% for the process with ozone backwashing, whereas the resistance was restored by 10.8% for the process with oxygen backwashing. Despite the periodical ozone backwashing and chemical cleaning, irreversible fouling gradually increased approximately 3 to 4%. Approximately 97.6% and 15% turbidity and TOC were removed by ceramic membrane filtration, respectively. Therefore, the integrated process with ozonation and ceramic membrane filtration is a potential greywater treatment process.

• Mass Spectrometry Letters
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• v.15 no.1
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• pp.40-48
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• 2024

Capacity of the analytical/quantitative evaluation techniques to satisfy both qualitative and quantitative considerations for effective extraction of marigold oleoresins/xanthophylls and their potential as anti-mycotic and antioxidant activity was assessed. Accelerated solvent extraction (ASE), Soxhlet extraction (SE), Supercritical fluid extraction (SCFE), Cold extraction (CE), and ultrasonically assisted extraction (USE) techniques were evaluated for extraction of oleoresin/xanthophyll content from Tagetes erecta (Var. Pusa Narangi Genda) with respect to solvent consumption, extraction time, reproducibility, and yield. Followed by the antifungal and antioxidant activity evaluation. The overall yield of Tagetes oleoresin was higher in ASE (64.5 g/kg) followed by SE (57.3 g/kg), USE (50.7 g/kg), SCFE (45.3 g/kg) and CE (31.6 g/kg). The lutein esters represented more than 80% of the constituents. Further, xanthophyll/ lutein content in oleoresin was found to be quite higher in HPLC (r2 = 0.996) analysis than in the AOAC recommended UV spectrophotometer analysis. The oleoresin exhibited moderate antioxidant activity (DPPH assay) and antifungal activity against three phytopathogenic fungi. Based on the various parameters, the reproducibility of ASE was better (0.3-8.0%) than that of SE (0.5-12.9%), SCFE (0.2-9.4%), USE (0.3-12.4%) and CE (0.8-15.3%). ASE with (RSD 1.6%) is preferred being faster, reproducible, uses less solvent, robust and automation allows sequential extraction of the sample in less time.

• Clinical and Experimental Reproductive Medicine
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• v.31 no.1
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• pp.29-39
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• 2004

Objectives: This study was performed to evaluate the laboratory system for successful PGD using fluorescence in situ hybridization (FISH) and the clinical outcome of PGD cycles in five years experiences. Methods: A total of 181 PGD-FISH cycles of 106 couples were performed, and diagnosed chromosome normality in the preimplantation embryos. The laboratory and clinical data were classified by the following optimization steps, and statistically analyzed. Phase I: Blastomere biopsy with two kinds of pipettes, removal of cytoplasmic proteins without treatment of pepsin and culture of biopsied embryos with single medium; Phase II: Blatomere biopsy with single pipette, removal of cytoplasmic proteins with pepsin and culture of biopsied embryos with single medium; Phase III: Blastomere biopsy with single pipette, removal of cytoplasmic proteins with pepsin and culture of biopsied embryos with sequential media. Results: A total of 3, 209 oocytes were collected, and 83.8% (2, 212/2, 640) of fertilization rate was obtained by ICSI procedure. The successful blastomere biopsies were accomplished in 98.6% (2, 043/2, 071) of embryos, and the successful diagnosis rate of FISH was 94.7% (1, 935/ 2, 043) of blastomeres from overall data. Embryo transfers with normal embryos were conducted in 93.9% (170/181) of started cycles. There was no difference in the successful rate of biopsy and diagnosis among Phase I, II and III. However, the pregnancy rate per embryo transfer of Phase III (38.8%, 26/67) was significantly (p<0.05) higher than those of Phase I (13.9%, 5/36) and Phase II (14.9%, 10/67). Conclusions: The laboratory optimization and experience for the PGD with FISH procedure can increase the pregnancy rate to 38.8% in the human IVF-ET program. Our facility of PGD with FISH provides the great possibility to get a normal pregnancy for the concerned couples by chromosomal aberrations.