• Journal of the Korean Geographical Society
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• v.45 no.6
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• pp.788-805
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• 2010

The present USN (Ubiquitous Sensor Networks) node deployment practices have many limitations in terms of positional connectivity. The aim of this research was to minimize a redundancy of USN route nodes, by integrating spatially weighted parameters such as visibility, proximity to cell center, road density, building density and cell overlapping ratio into a comprehensive GIS database. This spatially weighted approach made it possible to reduce the number of route nodes (11) required in the study site as compared to that of the grid network method (24). The field test for RSSI (Received Signal Strength Indicator) indicates that the spatially weighted deployment could comply with the quality assurance standard for node connectivity, and that reduced route nodes do not show a significant degree of signal fluctuation for different site conditions. This study demonstrated that the spatially weighted deployment can be used to minimize a redundancy of USN route nodes in a routine manner, and the quantitative evidence removing a redundancy of USN route nodes could be utilized as major tools to ensure the strong signal in the USN, that is frequently encountered in real applications.

• Journal of Korea Spatial Information System Society
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• v.10 no.1
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• pp.51-63
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• 2008

Previous studies for routing In USN (Ubiquitous Sensor Networks) appear to be unreliable due to the dependence on non-spatial data and the lack of map overlay analysis. Multiple spatial parameters and radio propagation modeling techniques were integrated to derive RSSI (Received Signal Strength Indicator) value between route nodes and produce a highly reliable path map. It was possible to identify area-wide patterns of USN route subject to many different Influences (e.g. the specific effects of radio blocking factors such as the visible area, road area, cell duplicated area, and building density), which cannot be acquired by traditional non-spatial modeling. The quantitative evidence concerning the USN route for individual cell as well as entire study area would be utilized as major tools to visualize paths in real-time and to select alternative path when failure or audition of route node occurs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.97-105
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• 2015

Multiresponse optimization (MRO) seeks to find the setting of input variables, which optimizes the multiple responses simultaneously. The approach of weighted mean squared error (WMSE) minimization for MRO imposes a different weight on the squared bias and variance, which are the two components of the mean squared error (MSE). To date, a weighted sum-based method has been proposed for WMSE minimization. On the other hand, this method has a limitation in that it cannot find the most preferred solution located in a nonconvex region in objective function space. This paper proposes a Tchebycheff metric-based method to overcome the limitations of the weighted sum-based method.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.3
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• pp.187-200
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• 2023

This study analyzed the seismic fragility of bored tunnels based on their surrounding conditions and suggested a representative seismic fragility model. By analyzing the existed seismic fragility models developed for bored tunnels, we developed weighted combination models for each surrounding conditions, such as ground conditions and depth of the tunnel. The seismic fragility curves use the peak ground acceleration (PGA) as a parameter. When the PGA was 0.3 g, the probability of damage exceeding minor or slight damage was 20% for depth of 50 m or less, 10% for depth between 50 m and 100 m, and 3% for depth of 100 m or more. It was also found that the probability of damage was higher for the same PGA and depth when the surrounding ground was rock rather than soil. The probability of damage decreases as the depth increase. This study is expected to be used for developing a comprehensive seismic fragility function for tunnels in the future.

• Journal of Cadastre & Land InformatiX
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• v.47 no.1
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• pp.37-51
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• 2017

Despite the improvement in accuracy of heavy rain forecasting, socioeconomic costs due to heavy rain hazards continue to increase. This is due to a lack of understanding of the effects of weather. In this study, the risk of heavy rain hazard was analyzed using the concepts of hazard, vulnerability, and exposure, which are key concepts of impact forecast presented by WMO. The potential impacts were constructed by the exposure and vulnerability variables, and the hazard index was calculated by selecting three variables according to the criteria of heavy rain warning. Weights of the potential impact index were calculated by using PCA and hazard index was calculated by applying the same weight. Correlation analysis between the potential impact index and damages showed a high correlation and it was confirmed that the potential impact index appropriately reflects the actual damage pattern. The heavy rain hazard risk was estimated by using the risk matrix consisting of the heavy rain potential impact index and the hazard index. This study provides a basis for the impacts analysis study for weather warning with spatial/temporal variation and it can be used as a useful data to establish the local heavy rain hazard prevention measures.

• Journal of the Economic Geographical Society of Korea
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• v.22 no.4
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• pp.555-575
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• 2019

Though housing market varies spatially, housing policy is limited in reflecting detailed regional differentiation. This study looked at the differences in Seoul Gu Districts' response to housing policy for the efficient implementation of housing policies in the future. Housing policy index was established by each Gu-districts' according to investigated housing policies from 2003 to 2018, weighted in two categories(financial/urban planning) and the status of designated areas. The VECM model was established to analyze the impact of the housing policy on the housing market. According to the analysis, although housing policies were established in response to market prices change, the impact of policies on prices was lower than the impact of vice versa. The housing policy's impact to the housing market is limited in some areas in northeastern Seoul. These results show that there are differences in the responses to housing policy in Seoul districts', and therefore detailed consideration of the differences in the regional aspects of housing policy is needed.