• KNOM Review
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• v.24 no.1
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• pp.1-12
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• 2021

VM (Virtual Machine) live migration is a server virtualization technique for deploying a running VM to another server node while minimizing downtime of a service the VM provides. Currently, in cloud data centers, VM live migration is widely used to apply load balancing on CPU workload and network traffic, to reduce electricity consumption by consolidating active VMs into specific location groups of servers, and to provide uninterrupted service during the maintenance of hardware and software update on servers. It is critical to use VMlive migration as a prevention or mitigation measure for possible failure when its indications are detected or predicted. In this paper, we propose two VNF live migration methods; one for predictive load balancing and the other for a proactive measure in failure. Both need machine learning models that learn periodic monitoring data of resource usage and logs from servers and VMs/VNFs. We apply the second method to a vEPC (Virtual Evolved Pakcet Core) failure scenario to provide a detailed case study.

• Journal of Korean Academy of Nursing
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• v.47 no.5
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• pp.676-688
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• 2017

Purpose: The purpose of this study was to analyze the migration patterns of new nurses and experienced nurses and to identify the factors influencing inter-regional migration for solving regional imbalances of clinical nurses in South Korea. Methods: This study involved a secondary analysis of data from the Health Insurance Review and Assessment Service (HIRA). Data were analyzed using descriptive statistics and multiple logistic regression analysis. Results: New nurses tended to migrate from Kyunggi to Seoul. However, experienced nurses tended to migrate from Seoul and Chungchung to Kyunggi. Significant predictors of inter-regional migration among new nurses were location and nurse staffing grade of hospitals. Significant predictors of inter-regional migration among experienced nurses were location, hospital type, nurse staffing grade, ownership of hospitals and age of nurses. Conclusion: Inter-regional migration occupied a small portion of total hospital movement among clinical nurses. The regional imbalances of nurses were not caused by the migration from non-metropolitan areas to Seoul. Nurse shortage problems in the small and medium hospitals of the non-metropolitan area can be solved only through improvement of work environment.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.14-15
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• 2007

Now-a-days, data and task migration in collaborative work provides enormous facilities to users. Here, we propose an ontology-based information management scheme to facilitate data and task migration in collaborative work. This ontologybased model will help us to organize huge information (e.g. device status, runtime state etc.) efficiently.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.12
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• pp.2707-2718
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• 2009

Enterprises saved and controled data using individual and various database which were occurred on business. The saved data that were existed in the database were approached by business processing for specified achievement of service's aims and were occurred frequently data migration. This research propose the data migration method using XMDR-DAI(eXtended Meta-Data Registry-Data and Integration) that were occurred by approaching and integration in the process of business processing based on sql query.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.139-144
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• 2007

To delineate subglacial and englacial images of the western Fourcade Glacier in Antarctica, GPR data were acquired along a 470 m profile in November 2006. Signature deconvolution, migration velocity analysis, and finite difference depth migration were effective in increasing vertical resolution, obtaining the velocity function, and yielding clear depth images of the mixed-phase single-channel data, respectively. The source signature was extracted through stacking reflection signals from the basement. The deconvolution successfully compressed the source signatures to increase temporal resolution and attenuated reverberations. Medium velocities were analyzed with 112 diffraction events by the constant-velocity migration method based on the Stolt algorithm. Finally, depth migration based on the finite difference algorithm provided clear englacial and subglacial images in the laterally-varying velocity field.

• The Korean Journal of Applied Statistics
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• v.32 no.4
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• pp.517-541
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• 2019

According to the OECD (2015) and UN (2017), Korea was classified as an immigration country. The designation as an immigration country means that net migration will remain positive and international migration is likely to affect population growth. KOSTAT (2011) used a model with more than 15 parameters to divide sexes, immigration and emigration based on the Wilson (2010) model, which takes into account population migration factors. Five years later, we assume the average of domestic net migration rate for the last five years and foreign government policy likely quota. However, both of these results were conservative estimates of international migration and provide different results than those used by the OECD and UN to classify an immigration country. In this paper, we proposed a stochastic projection on international migration using nonparametric model (FDM by Hyndman and Ullah (2007) and Coherent FDM by Hyndman et al. (2013)) that uses a functional data model for the international migration data of Korea from 2000-2017, noting the international migration such as immigration, emigration and net migration is non-linear and not linear. According to the result, immigration rate will be 1.098(male), 1.026(female) in 2018 and 1.228(male), 1.152(female) in 2025 per 1000 population, and the emigration rate will be 0.907(male), 0.879(female) in 2018 and 0.987(male), 0.959(female) in 2025 per 1000 population. Thus the net migration is expected to increase to 0.191(male), 0.148(female) in 2018 and 0.241(male), 0.192(female) in 2025 per 1000 population.

• IEMEK Journal of Embedded Systems and Applications
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• v.9 no.4
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• pp.205-210
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• 2014

Cache based live migration method utilizes a cache, which is accessible to both side (remote and local), to reduce the virtual machine migration time, by transferring only irredundant data. However, address space layout randomization (ASLR) is proved to reduce the memory duplicate ratio between targeted migration memory and the migration cache. In this pager, we analyzed the behavior of ASLR to find out how it changes the physical memory contents of virtual machines. We found that among six virtual memory regions, only the modification to stack influences the page-level memory duplicate ratio. Experiments showed that: (1) the ASLR does not shift the heap region in sub-page level; (2) the stack reduces the duplicate page size among VMs which performed input replay around 40MB, when ASLR was enabled; (3) the size of memory pages, which can be reconstructed from the fresh booted up state, also reduces by about 60MB by ASLR. With those observations, when applying cache-based migration method, we can omit the stack region. While for other five regions, even a coarse page-level redundancy data detecting method can figure out most of the duplicate memory contents.

• Communications for Statistical Applications and Methods
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• v.27 no.3
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• pp.385-395
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• 2020

We present a new maximum likelihood approach to estimate demographic history using genomic data sampled from two populations. A demographic model such as an isolation-with-migration (IM) model explains the genetic divergence of two populations split away from their common ancestral population. The standard probability model for an IM model contains a latent variable called genealogy that represents gene-specific evolutionary paths and links the genetic data to the IM model. Under an IM model, a genealogy consists of two kinds of evolutionary paths of genetic data: vertical inheritance paths (coalescent events) through generations and horizontal paths (migration events) between populations. The computational complexity of the IM model inference is one of the major limitations to analyze genomic data. We propose a fast maximum likelihood approach to estimate IM models from genomic data. The first step analyzes genomic data and maximizes the likelihood of a coalescent tree that contains vertical paths of genealogy. The second step analyzes the estimated coalescent trees and finds the parameter values of an IM model, which maximizes the distribution of the coalescent trees after taking account of possible migration events. We evaluate the performance of the new method by analyses of simulated data and genomic data from two subspecies of common chimpanzees in Africa.

• Journal of Korean Tunnelling and Underground Space Association
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• v.6 no.3
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• pp.247-258
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• 2004

Two 3-dimensional data processing techniques to predict the fractured zone ahead of a tunnel face by the tunnel seismic survey were proposed so that the geometric formation of the fractured zone could be estimated. The first 3-dimensional data processing technique was developed based on the principle of ellipsoid, The input data needed for the 3D migration can be obtained from the 2-dimensional tunnel seismic prediction (TSP) test where the TSP test should be performed in each sidewall of a tunnel. The second 3-dimensional migration technique that was developed based on the concept of wave travel plane was proposed. This technique can be applied when the TSP is operated with sources in one sidewall of a tunnel while the receivers are installed in both sidewalls. New migration technique was applied to an in-situ tunnelling site. The 3-dimensional migration was performed using measured TSP data and its results were compared with the geological investigation results that were monitored during tunnel construction. This comparison revealed that the proposed migration technique could reconstruct the discontinuity planes reasonably well.

• Proceedings of the KSEEG Conference
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• 2002.04a
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• pp.156-158
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• 2002

Reverse-time migration has no dip limitations and one of the most promising methods to preserve true amplitudes. We applied 3-D prestack reverse time migration based on a pseudo-spectral implementation of the acoustic wave equation to the SEG/EAGE salt dome synthetic data set. We were able to illuminate sub salt reflectors of the SEG/EAGE salt model that were barely observable in the Kirchhoff migration images. Using the pseudo-spectral modeling technique, we could implement reverse-time migration within the core memory, which could be equipped to a personal computer.