• Title/Summary/Keyword: migration

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A Resource Reduction Scheme with Low Migration Frequency for Virtual Machines on a Cloud Cluster

  • Kim, Changhyeon;Lee, Wonjoo;Jeon, Changho
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.7 no.6
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    • pp.1398-1417
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    • 2013
  • A method is proposed to reduce excess resources from a virtual machine(VM) while avoiding subsequent migrations for a computer cluster that provides cloud service. The proposed scheme cuts down on the resources of a VM based on the probability that migration may occur after a reduction. First, it finds a VM that can be scaled down by analyzing the history of the resource usage. Then, the migration probability is calculated as a function of the VM resource usage trend and the trend error. Finally, the amount of resources needed to eliminate from an underutilized VM is determined such that the migration probability after the resource reduction is less than or equal to an acceptable migration probability. The acceptable migration probability, to be set by the cloud service provider, is a criterion to assign a weight to the resource reduction either to prevent VM migrations or to enhance VM utilization. The results of simulation show that the proposed scheme lowers migration frequency by 31.6~60.8% depending on the consistency of resource demand while losing VM utilization by 9.1~21.5% compared to other known approaches, such as the static and the prediction-based methods. It is also verified that the proposed scheme extends the elapsed time before the first occurrence of migration after resource reduction 1.1~2.3-fold. In addition, changes in migration frequency and VM utilization are analyzed with varying acceptable migration probabilities and the consistency of resource demand patterns. It is expected that the analysis results can help service providers choose a right value of the acceptable migration probability under various environments having different migration costs and operational costs.

Migration Strategies for Temporal Data based on Time-Segmented Storage Structure

  • Yun, Hongwon
    • Proceedings of the IEEK Conference
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    • 2000.07a
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    • pp.329-332
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    • 2000
  • Research interests on temporal data have been almost focused on data models. There has been relatively less research in the area of temporal data management. In this paper, we propose two data migration strategies based on time-segmented storage structure: the migration strategy by Time Granularity, the migration strategy by LST-GET. We describe the criterion for data migration and moving process. We simulated the performance of the migration strategy by Time Granularity in order to compare it with non-segmentation method. We compared and analyzed two data migration strategies for temporal data.

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The Migration Scheme between Groups in the Multi-population Genetic Algorithms (다개체군 유전자 알고리즘의 집단간 이주 기법)

  • 차성민;권기호
    • Proceedings of the IEEK Conference
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    • 2000.11c
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    • pp.9-12
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    • 2000
  • Genetic algorithm is a searching method which based on the law of the survival of the fittest. Multi-population Genetic Algorithm is a modified form of Genetic Algorithm, which was devised for covering the defect of general genetic algorithm. The core of multi-population genetic algorithm is said to be the migration schemes. The fitness-based migration scheme and the random migration scheme are currently used. In this paper, a new migration scheme, ‘the migration scheme between groups’, is suggested, and compared to the general two migration schemes.

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Enhancement of Cell Migration by Corticotropin-Releasing Hormone (CRH) in Human Gastric Cancer Cell Line, MKN-28 (Corticotropin-Releasing Hormone (CRH)에 의한 인간 위암 세포(MKN-28)의 Migration 증가)

  • Cheon, Soyoung;Cho, Daeho
    • IMMUNE NETWORK
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    • v.4 no.4
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    • pp.244-249
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    • 2004
  • Background: Corticotropin-Releasing Hormone (CRH), an important regulator of stress response, has a potent immunoregulatory effect with the ability to promote the growth of various cancer through CRH receptor type 1 under stress. Although the metastasized cancers through cell migration are more aggressive than the primary cancers, little is known about the effect of CRH on cell migration. Gastric cancer is prone to metastasize to other tissues and it is reported that gastric cancer is response to various stresses such as oxidative stress. Herein, we studied the relationship between CRH and gastric cancer cell migration. Methods: We used gastric cancer cell line, MKN-28 and tested the CRH receptor type 1 expression on MKN-28 by RT-PCR. To examine the change in the ability of migration by CRH in MKN-28, cells were incubated with CRH and then migration ability was measured using a cell migration assay. Results: We confirmed that CRH receptor type 1 was expressed in MKN-28 and HaCaT cells. The migration ability of MKN-28 cells was increased by CRH in a time-, dose- dependent manner. Conclusion: These data suggest that CRH increases migration ability in gastric cancer cell line and that CRH may be a critical regulator in the metastasis of gastric cancer cell.

Exploratory Spatial Data Analysis (ESDA) for Age-Specific Migration Characteristics : A Case Study on Daegu Metropolitan City (연령별 인구이동 특성에 대한 탐색적 공간 데이터 분석 (ESDA) : 대구시를 사례로)

  • Kim, Kam-Young
    • Journal of the Korean association of regional geographers
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    • v.16 no.5
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    • pp.590-609
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    • 2010
  • The purpose of the study is to propose and evaluate Exploratory Spatial Data Analysis(ESDA) methods for examining age-specific population migration characteristics. First, population migration pyramid which is a pyramid-shaped graph designed with in-migration, out-migration, and net migration by age (or age group), was developed as a tool exploring age-specific migration propensities and structures. Second, various spatial statistics techniques based on local indicators of spatial association(LISA) such as Local Moran''s $I_i$, Getis-Ord ${G_i}^*$, and AMOEBA were suggested as ways to detect spatial dusters of age-specific net migration rate. These ESDA techniques were applied to age-specific population migration of Daegu Metropolitan City. Application results demonstrated that suggested ESDA methods can effectively detect new information and patterns such as contribution of age-specific migration propensities to population changes in a given region, relationship among different age groups, hot and cold spot of age-specific net migration rate, and similarity between age-specific spatial clusters.

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Theoretical Migration Estimation of Acetaldehyde and Butyraldehyde from Polyethylene Terephthalate (PET) into Fermented Food Simulants (PET식품 용기에서 발효 모사 식품으로 전이되는 아세트알데히드와 부틸알데히드 예측 모델)

  • Lee, Daeun;Jeon, Hyunpyo;Kim, Sanghun
    • Journal of Environmental Health Sciences
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    • v.42 no.3
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    • pp.160-168
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    • 2016
  • Objectives: Materials coming into contact with food may result in the migration of chemical substances into the food. To protect consumers from exposure, Regulation (EU) No. 10/2011 specifies the use of standard migration tests. Polyethylene terephthalate (PET), widely used for food packaging materials, has drawn the attention of researchers because unwanted migration of PET into food might occur when consumers reuse packaging material. The aim of this study was to predict and develop a migration model for two components, acetaldehyde and butyraldehyde in PET, into food simulants under conditions of changing pH and solvents, such as those observed in fermented foods like kimchi or sauerkraut. Methods: Using a migration model based on Fick's second law of diffusion in one dimension, the migration of acetaldehyde and butyraldehyde from PET into a simulant of fermented food at $20^{\circ}C$ over 10 days was evaluated. The simulant for fermented food was modelled as 10% ethanol for three days, followed by 3% acetic acid for seven days. Results: The migration of acetaldehyde into the 10% ethanol was 0.36 times that of a simulated fermented food system, while that of butyraldehyde was 1.34 times greater. These results may have been influenced by the chemical interactions among the migrants, polymers and simulants, as well as by the solubilities of the migrants in polymers and simulants. Conclusion: Because food simulants have a limited capacity to mimic real food systems under the current migration model, an appropriate simulant and migration test should be considered in the case of increasing acidity. Furthermore, since the accuracy of the worst-case estimation of migration predicted by the current model is severely limited under changing food conditions, food simulants and their interactions should be further investigated with respect to conservative migration modelling.

The Linkage between Planned and Spontaneous Migration: The Roles of the Migration on Coffee Production in Dak Lak, Vietnam (계획 이주와 자발적 이주 간 연계 -베트남 닥락 성 커피 생산에서 이주의 역할-)

  • Chung, Su-Yeul
    • Journal of the Economic Geographical Society of Korea
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    • v.16 no.3
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    • pp.344-358
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    • 2013
  • Vietnam's growth as the second largest coffee producer in the world has been fueled by domestic migration into central highlands. However, the detail migration processes have not been explicitly discussed. In particular, the existing literatures tend to describe the migration flow in a framework of planned migration versus spontaneous migration, paying less attention to the linkage between them. With a case study of Dak Lak province which is the leading robusta producer in Vietnam, this research investigates the linkage between planned and spontaneous migration in a multiscalar approach. The statistic data allow the researcher to know temporal association between the two type of migration in a provine scale. The survey and interview about two coffee-producing communes - Ea H'Ding in Cu M'gar district and Doan Ket in Krung Buk district - inform us that the linkage between planned and spontaneous migration is contingent to the local contexts including ethnic composition, timing of settlements, governement's development program, and timing of a large flow of in-migration.

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Effect of particle migration on the heat transfer of nanofluid

  • Kang, Hyun-Uk;Kim, Wun-Gwi;Kim, Sung-Hyun
    • Korea-Australia Rheology Journal
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    • v.19 no.3
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    • pp.99-107
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    • 2007
  • A nanofluid is a mixture of solid nanoparticles and a common base fluid. Nanofluids have shown great potential in improving the heat transfer properties of liquids. However, previous studies on the characteristics of nanofluids did not adequately explain the enhancement of heat transfer. This study examined the distribution of particles in a fluid and compared the mechanism for the enhancement of heat transfer in a nanofluid with that in a general microparticle suspension. A theoretical model was formulated with shear-induced particle migration, viscosity-induced particle migration, particle migration by Brownian motion, as well as the inertial migration of particles. The results of the simulation showed that there was no significant particle migration, with no change in particle concentration in the radial direction. A uniform particle concentration is very important in the heat transfer of a nanofluid. As the particle concentration and effective thermal conductivity at the wall region is lower than that of the bulk fluid, due to particle migration to the center of a microfluid, the addition of microparticles in a fluid does not affect the heat transfer properties of that fluid. However, in a nanofluid, particle migration to the center occurs quite slowly, and the particle migration flux is very small. Therefore, the effective thermal conductivity at the wall region increases with increasing addition of nanoparticles. This may be one reason why a nanofluid shows a good convective heat transfer performance.

A Time-Segmented Storage Structure and Migration Strategies for Temporal Data (시간지원 데이터를 위한 분리 저장 구조와 데이터 이동 방법)

  • Yun, Hong-Won;Kim, Gyeong-Seok
    • The Transactions of the Korea Information Processing Society
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    • v.6 no.4
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    • pp.851-867
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    • 1999
  • Numerous proposals for extending the relational data model as well as conceptual and object-oriented data models have been suggested. However, there has been relatively less research in the area of defining segmented storage structure and data migration strategies for temporal data. This paper presents the segmented storage structure in order to increment search performance and the two data migration strategies for segmented storage structure. this paper presents the two data migration strategies : the migration strategy by Time granularity, the migration strategy by LST-GET. In the migration strategy by Time Granularity, the dividing time point to assign the entity versions to the past segment, the current segment, and future segment is defined and the searching and moving process for data validity at a granularity level are described. In the migration strategy by LST-GET, we describe the process how to compute the value of dividing criterion. searching and moving processes are described for migration on the future segment and the current segment and entity versions 새 assign on each segment are defined. We simulate the search performance of the segmented storage structure in order to compare it with conventional storage structure in relational database system. And extensive simulation studies are performed in order to compare the search performance of the migration strategies with the segmented storage structure.

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Factors Influencing Intention of Migration by Hospital Nurses in Korea (병원간호사의 해외취업 의향에 영향을 미치는 요인)

  • Lee, Eun-Joo;Son, Jung-Tae
    • Journal of Korean Academy of Nursing Administration
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    • v.16 no.4
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    • pp.437-445
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    • 2010
  • Purpose: The purpose of this study was to identify the factors influencing intention of migration by Korean hospital nurses. Methods: Using cross sectional correlational design, data were collected from 512 nurses working in 7 hospitals ranging in size from 300 to 900 beds in D city and K province of Korea. Data were analyzed by descriptive statistics, chi-square, and multiple hierarchical regression using the SPSS program. Results: There were significant differences in intention of migration by age, educational background, marital status, work experience, and yearly incomes. Although there was high intention of migration of the subjects, the level of preparation for migration was relatively low. The variables that were independently associated with intention of migration were graduates of RN-BSN program, personal factors of subjects, and environmental factors. Those who had lower perception on nursing images and work condition had significantly higher intention of migration than those who had higher perception. Full model accounted for 37.3% of the variance in intention of migration. Conclusion: To prevent brain drain of competent nurses in Korea, appropriate strategies to enhance work condition should be developed and the effect of migration of nurses should be investigated in further studies.