• Journal of the Korean Regional Science Association
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• v.40 no.1
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• pp.53-67
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• 2024

Regional migration is a problem faced by all non-metropolitan areas in Korea, but the extent of migration varies depending on regional economic conditions. This study examines how the extent of youth migration varies depending on the economic conditions of their birthplaces. The results showed that youth migration was more severe in areas suffering from population decline and aging problems. The smaller the economy and the weaker the financial independence of the region, the more severe the youth migration. In particular, commercial, educational, and cultural facilities, except for medical facilities, were not able to curb youth migration. In addition, there was a significant wage gap between those employed in the metropolitan area and those employed in the regions, regardless of their origin. This suggests that non-metropolitan areas are caught in a vicious cycle of regional economic deterioration and youth migration.

• Journal of the Korea Society of Computer and Information
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• v.17 no.5
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• pp.1-7
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• 2012

In this paper, we design and implement the simulator for WAN storage replication model performance evaluation in cloud computing environment. Each cloud of simulator is composed of virtual machine emulator and storage emulator. The virtual machine emulator is composed of read/write ratio module, the read/write sequence combination module, and the read/write request module. The storage emulator is composed of storage management module, data transfer module, read/write operations module, and overhead processing module. Using the simulator, we evaluate performance of migration scheme, pre-copy and the post-copy, considering about read/write ratio, network delay, and network bandwidth. Through simulation, we have confirmed that the average migration time of pre-copy was decreased proportional to the read operation. However, average migration time of post-copy was on the increase. Also, the average migration time of post-copy was increased proportional to the network delay. However, average migration time of pre-copy was shown uniformly. Therefore, we show that pre-copy model more effective to reduce the average migration time than the post-copy model. The average migration time of pre-copy and post-copy were not affected by the change of network bandwidth. Therefore, these results show that selects the storage replication model to be, the network bandwidth know not being the important element.

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2003.10a
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• pp.222-224
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• 2003

• Journal of Food Hygiene and Safety
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• v.25 no.3
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• pp.203-208
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• 2010

In this study, the level of migration of 5 kinds of volatile organic compounds (VOCs) (toluene, styrene, ethylbenzene, isopropylbenzene and n-propylbenzene) into distilled water from polystyrene-made food containers was measured using Purge&Trap combined with GC/FID. The contents of the VOCs which have regulatory limits in Korea food code only for material specification were determined under three exposure conditions which were 30 min at $60^{\circ}C$, 30 min at $95^{\circ}C$ and actual situation of instant noodle intake. The calibration curve of 5 compounds showed good linearity ($^r2$ = 0.9976~0.9995) within the concentration range of 1~50 ng/mL. The limit of detection (LOD) and limit of quantification (LOQ) were validated at range of 0.041~0.092 and 0.135~0.304 ng/mL, respectively. The average migration contents of 5 compounds were below 5 ng/mL except for styrene. The average contents of styrene were highly detected at $95^{\circ}C$ for 30 min exposure (52.71 ng/mL). Under actual condition at instant noodle intake, the average contents of styrene was 17.23 ng/mL. The results demonstrated that the migration rate of VOCs was related to storage temperature and time.

• Smart Media Journal
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• v.8 no.3
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• pp.41-46
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• 2019

In a MMORPG, a typical application of virtual environment systems, it is a common desire to play in a more realistic environment. However, it is very difficult to provide a latency-free virtual environment to a large user base, mainly due to the fact that the real environment must be configured on multiple servers rather than on single server and that data must be shared on the real server when users move from one region to another. Experiencing response delays continuously in the process of information synchronization between servers greatly deteriorates the degree of immersion. In order to solve this problem, it is necessary to minimize the response delay occurring in the information synchronization process between the servers. In this paper, we propose Migration Agent for efficient information synchronization between field servers providing information of virtual environment and minimizing response delay between Field Server and PC(Player Character) and implement it in cloud computing network. In the proposed system, CPU utilization of field server increased by 6 ~ 13%, and response time decreased by 5 ~ 10 seconds over the existing system in 70,000 ~ 90,000 PCs

• Journal of Korea Water Resources Association
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• v.41 no.4
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• pp.395-404
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• 2008

It is important to understand the complex, various migration features of the alluvial channels for river engineering. In this study, the morphological changes and migration features of alluvial channels were investigated by analyzing the aerial photographs of active channels between 1972 and 2004 in Hapyeong Intake Station, Nakdong river. The lower channels were migrated from left bank to right bank and showed the features of braided channel in 2004. The instability of lower channels was increased due to the increased channel slope and width. The sinuosity of lower channels was decreased with time. As time increased, the increasing rate of lower channel and lateral migration rate were decreased. As a result of meso-scale regime analysis by using bankfull discharge, multiple row bars were developed, and suspended sediment load was governed in the flow as a sand bed channel.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.7
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• pp.1567-1574
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• 2012

Since a migration method of the mobile agent is a factor that affects the overall performance of the entire distributed system, it is necessary to find efficient migration methods of the mobile agent within the sensor network and to collect and store data related to various components(server, sink and sensor node) of the sensor network, thereby providing consistent naming services. Accordingly, this paper presents design and implementation of MetaTable that is divided into MetaData where information on the sensor data server is stored and SubMetaData where various types of information on sink nodes and data on sensor nodes connected with the sink nodes is stored. Moreover, the paper also presented the implementation of forward migration of an active rule mobile agent applying the naming method based on RMI that used the meta_table and proposed the possibility of constructing efficient sensor network application environment. In this paper, for registration, release and retrieval methods suitable for new sensor network environment, we designed and implemented the naming agent by applying J2EE model based on RMI-IIOP(Internet Inter-ORB Protocol) technique.

• Journal of Ecology and Environment
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• v.44 no.3
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• pp.185-195
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• 2020

Background: The flathead grey mullet Mugil cephalus has the widest distribution among mugilid species. Recent studies based on mitochondrial DNA sequences showed that the species comprises at least 14 different groups, three of which occur in the northwest Pacific. We analyzed the otolith microchemistry of M. cephalus at several locations in Korea to improve understanding of migration pattern and population origin. Results: We collected 123 sagittal otoliths from seven locations and determined their concentrations of eight elements (⁷Li, ²⁴Mg, ⁵⁵Mn, ⁵⁷Fe, ⁶⁰Ni, ⁶³Cu, ⁸⁸Sr, and ¹³⁸Ba) using laser ablation inductively coupled plasma mass spectrometry. Mean otolith elemental ratios differed significantly among the locations. The Sr:Ca, Fe:Ca, and Ba:Ca ratios were significantly higher than others, and useful chemical signatures for investigating the habitat use of M. cephalus populations. We identified five diverse and complicated migration patterns using the otolith data that we collected: estuarine resident (type I), freshwater migrant (type II), estuarine migrant (type III), seawater resident (type IV), and seawater migrant (type V). A canonical discriminant analysis plot revealed separation of two groups (type II in the Yellow Sea vs. other types in remaining locations). Two locations on Jeju Island, despite their close proximity, had fish with quite different migration patterns, corroborating previous molecular studies that distinguished two groups of fishes. Conclusion: We successfully showed that the migration patterns of the Korean mullet varied by location. Only fish from the western sector of Jeju had a unique migration pattern, which is likely confined population in this area. Among the eight otolith elements measured, the Sr:Ca ratio was found to be the best indicator of migration pattern and population origin.

• Journal of the Korea Society for Simulation
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• v.24 no.4
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• pp.11-21
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• 2015

If the cloud computing environment is not sufficiently provide the required resources due to the number of virtual server to process the request, may cause a problem that the load applied to the specific server. Migration administrator receive the resources of each physical server for improving the efficiency of the virtual server that exists in the physical servers, and determines the migration destination based on the simulation results. But, there is more overhead predicting the future resource consumption of all the physical server to decide the migration destination through the simulation process in large and complex cloud computing environments. To solve this problem, we propose an improved prediction method with the simulation-based approach. The proposed method is a fuzzy-logic based priority model for VM migration. We design a proposed model with the DEVS formalism. And we also measure and compare a performance and migration count with existing simulation-based migration method. FPLM shows high utilization.

• Asian Journal of Atmospheric Environment
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• v.8 no.1
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• pp.1-14
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• 2014

Migration of methane ($CH_4$) gas from landfills to the surrounding environment negatively affects both humankind and the environment. It is therefore essential to develop management techniques to reduce $CH_4$ emissions from landfills to minimize global warming and to reduce the human risks associated with $CH_4$ gas migration. Oxidation of $CH_4$ in landfill cover soil is the most important strategy for $CH_4$ emissions mitigation. $CH_4$ oxidation occurs naturally in landfill cover soils due to the abundance of methanotrophic bacteria. However, the activities of these bacteria are influenced by several controlling factors. This study attempts to review the important issues associated with the $CH_4$ oxidation process in landfill cover soils. The $CH_4$ oxidation process is highly sensitive to environmental factors and cover soil properties. The comparison of various biotic system techniques indicated that each technique has unique advantages and disadvantages, and the choice of the best technique for a specific application depends on economic constraints, treatment efficiency and landfill operations.