• Bulletin of the Korean Chemical Society
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• v.26 no.11
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• pp.1723-1727
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• 2005

A generalized fractional diffusion equation (FDE) is presented, which describes the time-evolution of the spatial distribution of a particle performing continuous time random walk (CTRW) on a fractal lattice. For a case corresponding to the CTRW with waiting time distribution that behaves as $\psi(t) \sim (t) ^{-(\alpha+1)}$, the FDE is solved to give analytic expressions for the Green’s function and the mean squared displacement (MSD). In agreement with the previous work of Blumen et al. [Phys. Rev. Lett. 1984, 53, 1301], the time-dependence of MSD is found to be given as < $r^2(t)$ > ~ $t ^{2\alpha/dw}$, where $d_w$ is the walk dimension of the given fractal. A Monte-Carlo simulation is also performed to evaluate the range of applicability of the proposed FDE.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.3
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• pp.116-126
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• 2003

In this study, we research about the relationships of human longevity and environments, inducted the significant factors of longevity from the statistical analysis, and represented spatial distribution of longevity using geographic information system. The factors confining human longevity can be categorized by geography/geology, climate/weather, economy, and social welfare. After analyzing statistical data, dependent variable which means the longevity index is defined by the ratio of population more than 85 years old among population more than 65 years old. The results of analysis show that longevity are related with waterworks ratio, temperature, local tax ratio, and latitude. In this study we discussed about the spatial characteristics which are represented by variance of the longevity index and described a spatial relationship between the longevity index and significant factors which are chosen by statistical analysis. In the further study, in order to sustain the longevity of a region, it is necessary for the effective rural planning to propagate a longevity of rural areas.

• Journal of Ecology and Environment
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• v.35 no.1
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• pp.51-58
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• 2012

In this study, we investigated carabid beetles residing in the wetlands to understand their ecological adaptation and strategy selection associated with restricted resources and habitat limitation. The species richness, abundance, seasonal activity, and spatial distribution of the carabid beetles between the Mujechi Wetlands (wetland sites) and Mt. Jeongjok (mountain sites) have been compared. A total of 1,733 individual beetles from 30 species were collected and classified at the studied sites. The wetland sites were identified as having lower species richness and abundance for carabid beetles when compared with the adjacent mountain sites, whereas these beetles were observed to be dominant in the wetland sites than in the adjacent mountain sites. Calosoma inquisitor cyanescens, Carabus sternbergi sternbergi, and Carabus jankowskii jankowskii species were dominant in both the wetland and mountain sites. These species showed significantly different seasonal activity patterns in the wetland sites relative to the mountain sites. Although the three listed carabid species were observed to be widely distributed throughout the wetland sites, they still showed preference for drier sites, which clearly shows a distinction in their habitats. The results of the spatial-temporal distribution of carabid beetles in the wetland sites reflect their special strategies regarding space and time partitioning for maintaining their population. The distribution patterns of carabid beetles in the wetland sites also showed the desiccation gradient and environmental changes prevalent in wetlands. Ecological surveys, which use carabid beetles in the wetlands, can then be performed when restoring wetlands and for establishing management practices for improving the habitat quality.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.616-619
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• 2007

Nowadays, urbanized area expands its boundary, and distribution of urbanized area is gradually transformed into more complicated pattern. In Korea, SMA(Seoul Metropolitan Area) has outstanding urbanized area since 1950s. But it is ambiguous whether urban distribution is clustered or dispersed. This study aims to show the way in which expansion of urbanized area impacts on spatial distribution pattern of urbanized area. We use quadrat analysis, nearest-neighbor analysis and fractal analysis to know distribution pattern of urbanized area in time-series urban growth. The quadrat analysis indicates that distribution pattern of urbanized area is clustered but the cohesion is gradually weakened. And the nearest-neighbor analysis shows that point patterns are changed that urbanized area distribution pattern is progressively changed from clustered pattern into dispersed pattern. The fractal dimension analysis shows that 1972's distribution dimension is 1.428 and 2000's dimension is 1.777. Therefore, as time goes by, the complexity of urbanized area is more increased through the years. As a result, we can show that the cohesion of the urbanized area is weakened and complicated.

• Journal of Ocean Engineering and Technology
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• v.35 no.2
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• pp.150-160
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• 2021

To ensure the international competitiveness of the domestic offshore plant industry, a consensus has been formed regarding the requirement for large offshore basins for performing offshore plant performance verification. Accordingly, the Korea Research Institute of Ships & Ocean Engineering has built the world's largest deep ocean engineering basin (DOEB). The purpose of this study is to evaluate the characteristics of velocity distribution under various conditions of the DOEB. An independent measuring jig is designed and manufactured to measure the current velocities of many locations within a short time. The measurement jig is a 15-m-high triangular-truss structure, and the measurement sensors can move 15 m vertically through an electric motor-wire device. The current speed is measured under various impeller revolutions per minute and locations of the DOEB using the jig. The spatial distribution characteristics of the current velocity in the DOEB and the performance of the current generator are analyzed. The maximum speed is 0.56 m/s in the center of the DOEB water surface, thereby confirming sufficient current velocity distribution uniformity for model testing.

• Journal of Internet Computing and Services
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• v.8 no.2
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• pp.1-13
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• 2007

GPS/GIS and RFID technologies have been changing the paradigm af our society toward ubiquitous era. Especially, geographically distributed mobile agents with transporting objects need to be automatically recognizable and traceable under certain conditions. To do this, fundamental theories and technologies are required to specify and verify spatial and temporal behaviors of agents on geographical space. This paper presents a new formal method, called Calculus of Real-Time Distribution, Mobility, and Interaction (CaRDMI), for this purpose. For specification, CaRDMI defines a map, mobile agents with transporting objects. The movement of on agent is represented by a path on the map, consisting of a list of nodes and a list of edges with spatial and temporal constraints. Interactive constraints among agents are represented by synchronization modes on objects at nodes. These constraints are distinguishable features of CaRDMI from other methods. Especially, many-to-many timed synchronization constraints are noticeable. For verification, CaRDMI presents the spatial, temporal and interactive deduction rules and the spatial and temporal equivalence relations.

• Journal of the Korean Society of Safety
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• v.39 no.1
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• pp.96-103
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• 2024

The demand for mass calculation of offsite consequence analysis to conduct exhaustive single-unit or multi-unit Level 3 PSA is increasing. In order to perform efficient offsite consequence analyses, the Korea Atomic Energy Research Institute is conducting model optimization studies to minimize the analysis time while maintaining the accuracy of the results. A previous study developed a model optimization method using efficient plume segmentation and verified its effectiveness. In this study, we investigated the possibility of optimizing the model through particle size distribution setting by checking the reduction in analysis time and deviation of the results. Our findings indicate that particle size distribution setting affects the results, but its effect on analysis time is insignificant. Therefore, it is advantageous to set the particle size distribution as fine as possible. Furthermore, we evaluated the effect of multithreading and confirmed its efficiency. Future optimization studies should be conducted on various input factors of offsite consequence analysis, such as spatial grid settings.

• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.3
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• pp.33-40
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• 2007

This study is to grasp and analyse the temporal and spatial distribution of record-breaking heavy snowfall rarely occurred in the middle and southwest region of South Korea during March of 2004 and December of 2005 respectively. Snow cover area was extracted using the channels 1, 3 and 4 of NOAA AVHRR images and the snow depth distribution was spatially interpolated using snowfall data of meteorological stations. Using administration boundary and Digital Elevation Model from 1:5,000 NGIS digital map, the snowfall impact was assessed spatially and compared with the reports at that time. The damaged area by heavy snowfall over 15 cm snow depth could be identified successfully within the spatial extent of snowfall area extracted by NOAA AVHRR image.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.603-605
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• 1997

A new algorithm using 1-dimensional wavelet transform for autofocusing of optical instrument has been developed. Previous studies based on the conventional frequency analysis have shown that as the lens-object distance approaches the optimum value, the high frequency energy in the corresponding image shows a consistent increase. However, as conventional frequency analysis techniques hide spatial distribution of each band energy, shape information in the original signal cannot be easily utilized. In this paper, a newly devised wavelet based focus measuring scheme is presented. Unlike other frequency domain analysis techniques that simply produce "frequency-only" spectra, wavelet analysis provides a "time-frequency" localized view of a given signal. As a result, both frequency band filtering and spatial distribution filtering can easily be realized. Depending on the proposed focus quality measuring algorithm, a fast and reliable automatic focus adjustment of optical devices could be implemented.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.2
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• pp.13-20
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• 2009

Recently there is growing interest in LBS requiring real-time services and the spatial main memory DBMS for efficient Telematics services. In order to optimize existing disk-based spatial indexes of the spatial main memory DBMS in the main memory, spatial index structures have been proposed, which minimize failures in cache access by reducing the entry size. However, because the reduction of entry size requires compression based on the MBR of the parent node or the removal of redundant MBR, the cost of MBR reconstruction increases in index update and the efficiency of search is lowered in index search. Thus, to reduce the cost of MBR reconstruction, this paper proposed the RSMB (relative-sized MBR)compression technique, which applies the base point of compression differently in case of broad distribution and narrow distribution. In case of broad distribution, compression is made based on the left-bottom point of the extended MBR of the parent node, and in case of narrow distribution, the whole MBR is divided into cells of the same size and compression is made based on the left-bottom point of each cell. In addition, MBR was compressed using a relative coordinate and size to reduce the cost of search in index search. Lastly, we evaluated the performance of the proposed RSMBR compression technique using real data, and proved its superiority.