• Journal of KIISE
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• v.42 no.2
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• pp.169-176
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• 2015

The atomic write technique is a good solution to solve the problem of the double write buffer. The atomic write technique needs modified I/O subsystems (i.e., file system and I/O schedulers) and a special SSD that guarantees the atomicity of the write request. In this paper, we propose the writing unit aligned block allocation technique (for EXT4 file system) and the merge prevention of requests technique for the CFQ scheduler. We also propose an atomic write-supporting SSD which stores the atomicity information in the spare area of the flash memory page. We evaluate the performance of the proposed atomic write scheme in MariaDB using the tpcc-mysql and SysBench benchmarks. The experimental results show that the proposed atomic write technique shows a performance improvement of 1.4~1.5 times compared to the double write buffer technique.

• Journal of Korean Neurosurgical Society
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• v.63 no.1
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• pp.45-55
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• 2020

Objective : Fibrin sealants have been used for hemostasis, sealant for cerebrospinal fluid leakage, and adhesive barrier in neurosurgery. Further, as its clinical use and role of an effective drug delivery vehicle have been proposed. This study was performed to measure antibacterial activity and continuous local antibiotic release from different concentrations of vancomycin-impregnated fibrin sealant in vitro. Methods : Antibacterial activity was investigated by disk diffusion test by measuring the diameter of the growth inhibition zone of bacteria (methicillin-resistant Staphylococcus aureus, ATCC29213) from vancomycin-embedded fibrin sealant disc diluted at five different concentrations (C1-C5; 8.33, 4.167, 0.83, 0.083, and 0.0083 mg/disc, respectively). Continuous and conditioned release of vancomycin concentration (for 2 weeks and for 5 days, respectively) were also measured using high-performance liquid chromatography (HPLC) method. To mimic the physiologic wound conditions with in vitro, conditioned vancomycin release in phosphate buffer solution (PBS) was measured and replaced PBS for five consecutive days, half a day or completely daily. Results : In the disk diffusion test, the mean diameters of bacterial inhibition zone were 2.54±0.07 cm, 2.61±0.12 cm, and 2.13±0.15 cm (C1, C2, and C3 respectively) but 1.67±0.06 cm and 1.23±0.15 cm in C4 and C5, respectively. Continuous elution test elicited the peak release of vancomycin from the fibrin sealant at 48 hours, with continued release until 2 weeks. However, conditioned vancomycin release decreased to half or more on day 2, however, the sustainable release was measured over the therapeutic dose (10-20 ㎍/mL) for 5 days and 4 days in assays of half and total exchange of PBS. Conclusion : This study suggests that fibrin sealant can provide an efficient vehicle for antibiotic drug release in a wide range of neurosurgical procedures and the safe and effective therapeutic dose will be at the concentration embedded of 4.167 mg/disc or more of vancomycin.

• The KIPS Transactions:PartD
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• v.10D no.7
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• pp.1067-1076
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• 2003

Database sharing system (DSS) refers to a system for high performance transaction processing. In DSS, the processing nodes are locally coupled via a high speed network and share a common database at the disk level. Each node has a local memory and a separate copy of operating system. To reduce the number of disk accesses, the node caches database pages in its local memory buffer. In this paper, we propose a dynamic transaction routing algorithm to balance the load of each node in the DSS. The proposed algorithm is novel in the sense that it can support node-specific locality of reference by utilizing the primary copy authority assigned to each node; hence, it can achieve better cache hit ratios and thus fewer disk I/Os. Furthermore, the proposed algorithm avoids a specific node being overloaded by considering the current workload of each node. To evaluate the performance of the proposed algorithm, we develop a simulation model of the DSS, and then analyze the simulation results. The results show that the proposed algorithm outperforms the existing algorithms in the transaction processing rate. Especially the proposed algorithm shows better performance when the number of concurrently executed transactions is high and the data page access patterns of the transactions are not equally distributed.

• Journal of fish pathology
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• v.10 no.2
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• pp.125-135
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• 1997

The possibility of identification of families of antibacterial agent residues in fish tissue was studied by disk assay using three test organisms, Bacillus subtilis BGA, Micrococcus luteus ATCC 9341, and Bacillus cereus var. mycoides ATCC 11778. In the present method, a simple clean-up procedure was performed to obtain the aqueous solution from homogenized flounder muscle sample(10g) in Mcilvaine buffer. Then, aqueous solution was fractionated into A and B to be used in disk assay by choloroform and Sep-Pak $C_{18}$ cartridge column after being defatted in hexane. The chloroform layer of fraction A was used for the analysis of macrolide antibiotics(ML), sulfa drugs(SA), chloramphenicol(CP), and quinolone antibiotics(QN). Adsorbed materials to Sep-Pak $C_{18}$ of fraction B were also employed for the analysis of penicillins(PC), tetracyclines(TC), and nitrofuran derivatives(NF) Minimun-detectable concentrations by the present method were, $0.1{\mu}g$/g for oxytetracycline, tetracycline, doxycycline, spiramycin and ciprofloxacin, $0.025{\mu}g$/g for erythromycin and ampicillin, $1.0{\mu}g$/g for sodium nifurstyrenate and florfenical, $0.25{\mu}g$/g for sulfamonomethoxie and sulfadimethoxine, $2.5{\mu}g$/g for oxolinic acid and flumequine, and $15{\mu}g$/g for piromidic acid, respectively. Three test organisms showed different sensitivity patterns for each family of antibacterial agent. Sensitivity patterns were B. cereus > B. subtilis > M. luteus for TC and NF, M. luteus > B, subtilis > B. cereus for ML and PC, B. cereus = B. subtilis > M. luteus for CP and QN, and B. subtilis > B. cereus＝M. luteus for SA. The present method utilizing these characteristics could be useful as a routine screening test for the determination of family of antibacterial agent residues in fish tissue.

• Publications of The Korean Astronomical Society
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• v.23 no.2
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• pp.91-107
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• 2008

In this paper, we introduce the performance evaluation and development of Raw VLBI Data Buffer(RVDB) system for the synchronized playback processing of observed data in Korea-Japan Joint VLBI Correlator(KJJVC). The high-speed correlation processing system is under development so that the radio data obtained with 8192 channels and 8 Gbps speed from 16 stations will be able to be processed. When the recorded data of each station are played to correlator, the time synchronization of each station is very important because the correlator should process the data obtained with same time and condition. There are many types of recorder systems in the East Asia VLBI Network (EAVN). Therefore it is required to prepare the special time synchronized playback processing system to synchronize the time tag of observed data. The developed RVDB system consists of Data Input Output(DIO), 10GbE switch, and Disk Data Buffer(DDB). It can record the data with maximum 2 Gbps speed, and can play back the data to correlator with nominal 2 Gbps speed. To enable to play back the data of different playback system to the correlator, we developed the high-speed time synchronized playback processing system. We carried out the experiments of playing back and correlation for gigabit correlator and VCS trial product so as to confirm the performance of developed time synchronized playback processing system. In case of online and offline playing back experiment for gigabit correlator, we confirmed that the online and offline correlation results were the same. In case of playing back experiment for VCS trial product, we verified that the wide band and narrow band correlation results were also the same. Through the playing back experiments of RVDB system, the effectiveness of developed RVDB system was verified. In this paper, the system design, construction and experimental results are shown briefly.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.9
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• pp.1083-1095
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• 1999

최근 처리기와 입출력 시스템의 속도 차이가 점점 커짐에 따라 버퍼 캐쉬의 효율적인 관리가 더욱 중요해지고 있다. 버퍼 캐쉬는 블록 교체 정책과 선반입 정책에 의해 관리되며, 각 정책은 버퍼 캐쉬에서 블록의 가치 즉 어떤 블록이 더 가까운 미래에 참조될 것인가를 결정해야 한다. 블록의 가치는 응용들의 블록 참조 패턴의 특성에 기반하며, 블록 참조 패턴의 특성에 대한 정확한 분석은 올바른 결정을 가능하게 하여 버퍼 캐쉬의 효율을 높일 수 있다. 본 논문은 각 응용들의 블록 참조 패턴에 대한 특성을 분석하고 이를 자동으로 발견하는 기법을 제안한다. 제안된 기법은 블록의 속성과 미래 참조 거리간의 관계를 이용해 블록 참조 패턴을 발견한다. 이 기법은 2 단계 파이프라인 방법을 이용하여 온라인으로 참조 패턴을 발견할 수 있으며, 참조 패턴의 변화가 발생하면 이를 인식할 수 있다. 본 논문에서는 8개의 실제 응용 트레이스를 이용해 블록 참조 패턴의 발견을 실험하였으며, 제안된 기법이 각 응용의 블록 참조 패턴을 정확히 발견함을 확인하였다. 그리고 발견된 참조 패턴 정보를 블록 교체 정책에 적용해 보았으며, 실험 결과 기존의 대표적인 블록 교체 정책인 LRU에 비해 최대 57%까지 디스크 입출력 횟수를 줄일 수 있었다.Abstract As the speed gap between processors and disks continues to increase, the role of the buffer cache located in main memory is becoming increasingly important. The buffer cache is managed by block replacement policies and prefetching policies and each policy should decide the value of block, that is which block will be accessed in the near future. The value of block is based on the characteristics of block reference patterns of applications, hence accurate characterization of block reference patterns may improve the performance of the buffer cache. In this paper, we study the characteristics of block reference behavior of applications and propose a scheme that automatically detects the block reference patterns. The detection is made by associating block attributes of a block with the forward distance of the block. With the periodic detection using a two-stage pipeline technique, the scheme can make on-line detection of block reference patterns and monitor the changes of block reference patterns. We measured the detection capability of the proposed scheme using 8 real workload traces and found that the scheme accurately detects the block reference patterns of applications. Also, we apply the detected block reference patterns into the block replacement policy and show that replacement policies appropriate for the detected block reference patterns decreases the number of DISK I/Os by up to 57%, compared with the traditional LRU policy.

• The Transactions of the Korea Information Processing Society
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• v.4 no.4
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• pp.1076-1088
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• 1997

Data repliciation techniques of distributed database a allocation methods occures to overhead to change together all repkicas for consistency maintenance at updates .In case of data migration horizontal or vertical fragment migration has caused to caused to increase data communication.In this paper we purpose batch proxessing method groups the associated items of table and stores temporary table assciated with file relication and migrations.This method increase the usagility of system buffer in distributed trancsaction processing with a number of data inputs and updates.After all,it improved the perform-ance of distributed transaction system by reducing disk I\O processing time and the cost of data cimmunication among local sites.

• Journal of the Korea Computer Industry Society
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• v.5 no.9
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• pp.911-920
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• 2004

Intensive studies have been made in the area of VOD server. Multimedia files in the VOD sever are characterized with the large volume of data, the requirements of synchronization and real-time playback of streams. The basic goal of the study is to find an efficient mechanism to allow maximum number of users under the limited resources such as Bu11er size and disk bandwidth. we propose a efficient user-grouping policy for multi-casting services with dynamic monitoring and management of VOD sever resources. Simulation results show that the rate of buffer usage and QOS change of proposed scheme are about 23% performance improved than that of traditional methods. This implies that our method can allow much more users for given resources.

• Journal of Pharmaceutical Investigation
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• v.16 no.1
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• pp.1-7
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• 1986

The influences of sodium chloride, polyethylene glycol 4000 and 20000 on 5-fluorouracil release from disk type silicone polymer devices were examined in isotonic phosphate buffer. These water soluble cosolvent and sodium chloride caused devices to swell in aqueous media. Sodium chloride exerted the greatest influence on drug release. The addition of water soluble cosolvent or sodium chloride to silicone polymeric devices permitted controlled release of 5-fluorouracil, presumably due to the change of the physical microstructure of silicone network, and the solubility and diffusivity of 5-fluorouracil. It seemed that the water soluble drug was released through the hydrophilic pores or pathways formed in the device by the incorporation of a water soluble cosolvent or sodium chloride.

• Journal of the Korea Computer Industry Society
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• v.9 no.2
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• pp.53-62
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• 2008

Intensive studies have been made in the area of IPTV VOD server. The basic goal of the study is to find an efficient mechanism to allow maximum number of users under the limited resources such as Buffer utilization, disk performance and network bandwidth. The overlay multicast that has been recently presented as an alternative for the IP multicast has been getting much persuasion by the system resource and the network bandwidth and the advancement of the network cost. we propose a efficient overlay multi_casting network policy for multimedia services with multi media partition storage. Simulation results show that the rate of service number and service time of proposed scheme are about 23% performance improved than that of traditional methods. This implies that our method can allow much more users for given resources.