• Journal of the Korean Society of Environmental Restoration Technology
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• v.10 no.6
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• pp.120-129
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• 2007

Rapid urbanization has transformed the spatial pattern of urban land use or cover. This paper concentrates that changed characteristics of landscape structure in the Tancheon Watershed, from 1995 to 2003 were investigated using land cover map. We used FRAGSTATS software to calculate landscape indices to characterize the landscape structure. We found that built up area has been increased rapidly during the study period, while cultivated area and forest area have been decreased rapidly in the same period. From 1995 to 2003, built up area was increased from 19.73% to 39.62% and cultivated area and forest area was decreased 17.60% to 5.97% and 58.31% to 49.41%. Number of patches, mean euclidean nearest-neighbor distance, contagion index, Shannon's diversity index increased considerably from 1995 to 2003, also suggesting the landscape in the study area became more fragmented and heterogeneous. but because of continuously fragmentation, landscape became homogeneity. The study demonstrates that landscape metrics can be a useful indicator in landscape monitoring and landscape assessment.

• Korean Journal of Remote Sensing
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• v.22 no.5
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• pp.357-366
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• 2006

A traditional image analysis or classification method using satellite imagery is mostly based on the spectral information. However, the spatial information is more important according as the resolution is higher and spatial patterns are more complex. In this study, we attempted to compare and analyze the variogram properties of actual high resolution imageries mainly in the urban area. Through the several experiments, we have understood that the variogram is various according to a sensor type, spatial resolution, a location, a feature type, time, season and so on and shows the information related to a feature size. With simple modeling, we confirmed that the unique variogram types were shown unlike the classical variogram in case of small subsets. Based on the grasped variogram characteristics, we made a level index map for determining urban complexity or land-use classification. These results will become more and more important and be widely applied to the various fields of high-resolution imagery such as KOMPSAT-2 and KOMPSAT-3 which is scheduled to be launched.

• Journal of the Institute of Convergence Signal Processing
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• v.21 no.3
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• pp.127-132
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• 2020

In this study, the process of providing information necessary to remove physical barriers such as road slopes that obstruct the activities of the disabled is in progress. Through experiments, we implement a quantified road surface roughness index that enables the implementation of IoT-based systems necessary for the elderly and the disabled to safely move to their destination. As a preliminary study, a road surface measurement device using a gyroscope was devised. To check the roughness and flatness of the road surface, X, Y displacement, and acceleration displacement were measured using a gyroscope. By calculating the measured data, the roughness and flatness of the road surface were quantified from 0 to 100. We implemented an algorithm that divides this index into 4 stages, displays it on a map, and provides it to users. Finally, a system for the disabled and elderly electric wheelchair users to secure basic mobility was established.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.594-597
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• 2004

The ground subsidence that occurred in an abandoned coal mining area, Gaeun, Korea, was observed by using 25 JERS-1 SAR interferograms from November 1992 to October 1998. We estimated the subsidence on a subset of image pixels corresponding to point-wise permanent scatters (PSs) by exploiting a long temporal series of interferometric phases. The results were compared it with a distribution map of in situ examined crack level. PSs were identified by means of amplitude dispersion index and coherence of the interferograms. The measured subsidence rate represented the average velocity in a period of image acquisition and excluded complex nonlinear displacements such as an abrupt collapse. The mean line-of-sight velocity in the study area is 0.19cm/yr and an r.m.s. error is 0.18cm/yr. The center of the abandoned Gaeun coal mine (0.49cm/yr) and the area near to the Gaeun station (1.66cm/yr) were observed as most rapidly subsiding areas.

• Journal of Advanced Technology Convergence
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• v.2 no.2
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• pp.39-47
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• 2023

The purpose of this study is to examine the difference in cardiovascular changes between obese people and the general public using a treadmill. This study was conducted by recruiting 32 adult males who had no experience in hospital visits or treatment due to cardiovascular disease. The subjects were divided into an obese group and a general group based on BMI 25 and performed treadmill exercise for 12 minutes. SBP, DBP, HR, MAP, and PP before and after the treadmill were measured to see the difference in cardiovascular system changes. Data analysis was evaluated using an independent t-test. In the case of SBP, MAP, and PP, there were significant differences between groups (P<0.05). For DBP and HR, no significant difference was found between the two groups (P>0.05). The subjects of this study consisted only of healthy adult males in their 20s, and there is a limitation in that it was performed in a short time.

• Journal of the Korean Geotechnical Society
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• v.38 no.4
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• pp.59-70
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• 2022

There is a growing interest in evaluating earthquake damage and determining disaster prevention measures due to the magnitude 5.8 earthquake in Pohang, Korea. Since the liquefaction phenomena occurred extensively in the residential area as a result of the earthquake, there was a demand for research on liquefaction phenomenon evaluation and liquefaction disaster prediction. Liquefaction is defined as a phenomenon where the strength of the ground is completely lost due to a sudden increase in excess pore water pressure caused due to large dynamic stress, such as an earthquake, acting on loose sand particles in a short period of time. The liquefaction potential index, which can identify the occurrence of liquefaction and predict the risk of liquefaction in a targeted area, can be used to create a liquefaction hazard map. However, since liquefaction assessment using existing field testing is predicated on a single borehole liquefaction assessment, there has been a representative issue for the whole targeted area. Spatial interpolation and geographic information systems can help to solve this issue to some extent. Therefore, in order to solve the representative problem of geotechnical information, this research uses the kriging method, one of the geostatistical spatial interpolation techniques, and constructs a geotechnical information database for liquefaction and spatial interpolation. Additionally, the liquefaction hazard map was created for each return period using the constructed geotechnical information database. Cross validation was used to confirm the accuracy of this liquefaction hazard map.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.6
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• pp.579-587
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• 2015

Landslides are major natural geological hazards that result in a large amount of property damage each year, with both direct and indirect costs. Many researchers have produced landslide susceptibility maps using various techniques over the last few decades. This paper presents the landslide susceptibility results from the geographically weighted regression model using remote sensing and geographic information system data for landslide susceptibility in the Inje area of South Korea. Landslide locations were identified from aerial photographs. The eleven landslide-related factors were calculated and extracted from the spatial database and used to analyze landslide susceptibility. Compared with the global logistic regression model, the Akaike Information Criteria was improved by 109.12, the adjusted R-squared was improved from 0.165 to 0.304, and the Moran’s I index of this analysis was improved from 0.4258 to 0.0553. The comparisons of susceptibility obtained from the models show that geographically weighted regression has higher predictive performance.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.6
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• pp.37-45
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• 2005

Almost every year, Korea has been suffered from serious damages of lives and properties, due to landslides that are triggered by heavy rains in monsoon season. In this paper, we systematized the physically based landslide prediction model which consisted of 3 parts, infinite slope stability analysis model, groundwater flow model and soil depth model. To evaluate its applicability to the prediction of landslides, the data of actual landslides were plotted on the predicted areas on the GIS map. The matching rate of this model to the actual data was $84.8\%$. And the relation between hydrological and land form factors and potential landslide were analyzed.

• Journal of the Chungcheong Mathematical Society
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• v.33 no.1
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• pp.173-179
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• 2020

Let X be a compact space and Λ a finite index set. We deal with dynamical properties of iterated function systems on X. For an iterated function system 𝓕 on X, we prove that 𝓕 is c-expansive if and only if 𝓕^k is also c-expansive for each k ∈ ℕ. Furthermore we prove that the c-expansiveness of 𝓕 is equivalent to the original expansiveness of the shift map of it.

• Journal of Power Electronics
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• v.14 no.4
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• pp.778-787
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• 2014

This study presents an input filter resonance mitigation method for an AC-DC matrix converter. This method combines the advantages of the one-cycle control strategy and the active damping technique. Unnecessary sensors are removed, and system cost is reduced by employing the grid-side input currents as feedback to damp out LC resonance. A model that includes the proposed method and the input filter is established with consideration of the delay caused by the actual controller. A zero-pole map is employed to analyze model stability and to investigate virtual resistor parameter design principles. Based on a double closed-loop control scheme, the one-cycle control strategy does not require any complex modulation index control. Thus, this strategy can be more easily implemented than traditional space vector-based methods. Experimental results demonstrate the veracity of theoretical analysis and the feasibility of the proposed approach.