• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5B
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• pp.481-488
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• 2006

This paper suggests a novel approach of integrating the quasi-distributed watershed model SWAT with the fully-distributed groundwater model MODFLOW. Since the SWAT model has semi distributed features, its groundwater components hardly considers distributed parameters such as hydraulic conductivity and storage coefficient. Generating a detailed representation of groundwater recharge, head distribution and pumping rate is equally difficult. To solve these problems, the method of exchanging the characteristics of the hydrologic response units (HRUs) in SWAT with cells in MODFLOW by fully combined manner is proposed. The linkage is completed by considering the interaction between the stream network and the aquifer to reflect boundary flow. This approach is provisionally applied to Gyungancheon basin in Korea. The application demonstrates a combined model which enables an interaction between saturated zones and channel reaches. This interaction plays an essential role in the runoff generation in the Gyungancheon basin. The comprehensive results show a wide applicability of the model which represents the temporal-spatial groundwater head distribution and recharge.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.3
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• pp.33-38
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• 2013

Smart phones that are equipped with various types of sensors can monitor human beings, and their social activities and environments. Smart phone sensing systems are inevitable to lose sensing data at a certain region. It is more severe effect on opportunistic sensing because this sensing scheme is designed to read values from sensors when the state of numberous users meets pre-defined conditions. In this paper, we suggested an estimation model of missing data considering features of smart phone sensing to solve lower quality of collected data. This proposed model does not only reflect a temporal and spatial correlation, but also give high priority to participants who provide high quality data to improve the accuracy of estimated values. The experimental results show that our scheme is more accurate than previous scheme.

• Ocean and Polar Research
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• v.39 no.3
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• pp.169-179
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• 2017

The "GeoDrifter" is a newly-developed surface drifter with high temporal resolution. It is the first time that high-frequency drifters have been deployed in the East/Japan Sea. The purpose of this study is to introduce the phenomena experienced by these drifters flowing along with the Tsushima Current across the East/Japan Sea, focusing on high-frequency variability, and to discuss them in comparison with previous observations. The observed basin-scale circulation of the Tsushima Current generally coincides well with the known schematic circulation. The GeoDrifter trajectories also show inertial oscillations almost everywhere in the oceanic regions of the East/Japan Sea, strong semi-diurnal tidal currents in the western part of Korea Strait, diurnal currents much stronger than semi-diurnal currents in the upstream region of the Nearshore Branch off the Japanese coast, and many warm eddies in the Yamato Basin, all comparable to the observational results reported in the previous studies. An interesting point is that the semi-diurnal tidal currents undergo a great spatial variation in the western part of the Korea Strait. The observed features that cannot be explained are, among others, strong counter-clockwise motions with oscillating period about 51 hours appearing in the upstream region of the Nearshore Branch off the Japanese coast and the different tidal behaviors between upstream and downstream regions of the latter.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.181-186
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• 2006

An imaging method of seismic sources using time-reversal wave propagation is presented. The method is based on the time-reversal invariance and the spatial reciprocity of the wave equation. Time-reversal wave propagation has been used to image anomalous features of a midium in medical imaging, non destructive testing and waveform tomography. Seismogram is the record whose energy is propagated from the seismic source. If time-reversed seismogram propagates back into the medium, seismic energy is concentrated at the origin time of the event and at the source location. In this work, a staggered-grid finite-difference method of the elastic wave equation is parallelized for 3-D wave propagation simulation. With numerical experiments, we show that the time-reversal imaging will enable us to explore the spatio-temporal history of complex earthquake.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.2
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• pp.109-127
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• 2011

Atmospheric aerosols, small particles in the atmosphere, are one of the important parameters in climate change and human health. Additionally, accurate estimates of aerosol species are increasingly important in environmental impact assessment studies. Recent advances in global satellite remote sensing provide powerful tool for air quality monitoring. This study explores the potential usage of satellite derived data such as atmospheric aerosols for air quality monitoring as well as climate change study. The objectives of this study is to understand the general features of the global distribution of type dependent aerosols. A detailed spatio-temporal variability of the each different satellite dataset shows the variation of the global zonal average and specific geographical regions where the strong emission sources are located. Especially, significantly large aerosol amounts are observed in Asia and Africa because of the desert dust storm, anthropogenic and biomass burning emissions.

• Journal of the Korean Geographical Society
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• v.48 no.4
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• pp.509-532
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• 2013

Minimum Housing Standard is an instrument to cope with the problems of public health and community hygiene, deterioration of working class housing conditions appeared commonly in the process of capitalist industrialization and rapid rural-to-urban migration. This paper aims to examine the institutionalization of histories of minimum housing standard in the advanced countries, and analyze the spatio-temporal changes and characteristics of households failing to meet the New Minimum Housing Standard in Seoul Metropolitan since 1995. The analysis of this paper is based on the census data on population and housing. The results are as follows; Households failing to meet the New Minimum Housing Standard in Seoul are 501,000 households(1.368 million person, 14.4%). This means Seoul has overtaken the national average 11.8% for the first time and there are structurally marginal band of households who can not improve the housing conditions by themselves. In addition, the fact that the rate of Seoul households living in the marginal shelter including the basement and rooftop room is the highest in Korea means the housing quality issues of Seoul is serious. Spatial distribution of households failing to meet the standard is divided into the northeast area and the southwest area in Seoul. Main features of the households are female-headed families, middle and old-aged people, divorce families, lower educated people, under and graduate students, non-apartments, dweller in 15~20 year old houses.

• Review of Culture and Economy
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• v.20 no.2
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• pp.89-117
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• 2017

As the industrial paradigm shifts and the manufacturing industry declines, many changes also take place in the region as well. In this regard, interest in industrial heritage as a facet of cultural heritage is on the increase. In this paper, the meaning of regional 'cultural contents' as industrial heritage is investigated within the scope of specific region. It is meant to move beyond the viewpoint of considering industrial heritage as only relating to industrial machinery and relevant landmarks from the past. The concept of industrial heritage is established more clearly through the review policy and case study analysis of existing research; the analysis is conducted to investigate the characteristics associated with it, and then to explore how best to utilize it. In particular, this paper attempts to focus on how it operates within these parameters using a spatio-temporal context as much as possible, and concentrating on the recognition and experience of the subject of industrial heritage as being traceable through human story. This research is based on the case of 'Sapporo' which focuses on modern history based on historical importance, and the 'Cheongju' case study, which contrasts the former by focusing on urban regeneration using a spatial lens. This paper identifies the possibility of regional development through the examination of past identity and diversity in the present, and highlights the features that could be linked to future usability and development. In addition, it proposes the possibility that the cycle of regional development could change in the process of the different stages of territorialization, de-territorialization and re-territorialization.

• Korean Journal of Remote Sensing
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• v.34 no.6_3
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• pp.1427-1443
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• 2018

Object-based image analysis (OBIA) allows higher computation efficiency and usability of information inherent in the image, as it reduces the complexity of the image while maintaining the image properties. Superpixel methods oversegment the image with a smaller image unit than an ordinary object segment and well preserve the edges of the image. SLIC (Simple linear iterative clustering) is known for outperforming the previous superpixel methods with high image segmentation quality. Although the input parameter for SLIC, number of superpixels has considerable influence on image segmentation results, impact analysis for SLIC parameter has not been investigated enough. In this study, we performed optimal parameter analysis and evaluation of change detection for SLIC-based superpixel techniques using KOMPSAT data. Forsuperpixel generation, three superpixel methods (SLIC; SLIC0, zero parameter version of SLIC; SNIC, simple non-iterative clustering) were used with superpixel sizes in ranges of $5{\times}5$ (pixels) to $50{\times}50$ (pixels). Then, the image segmentation results were analyzed for how well they preserve the edges of the change detection reference data. Based on the optimal parameter analysis, image segmentation boundaries were obtained from difference image of the bi-temporal images. Then, DBSCAN (Density-based spatial clustering of applications with noise) was applied to cluster the superpixels to a certain size of objects for change detection. The changes of features were detected for each superpixel and compared with reference data for evaluation. From the change detection results, it proved that better change detection can be achieved even with bigger superpixel size if the superpixels were generated with high regularity of size and shape.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.29 no.1
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• pp.56-76
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• 2024

We for the first time made a successful longest continuous sectional observation in the East Sea by an underwater glider during 95 days from September 18 to December 21 2020 in the Korea along the 106 Line (129.1 °E ~ 131.5 °E at 37.9 °N) of the regular shipboard measurements by the National Institute of Fishery Science (NIFS) and obtained twelve hydrographic sections with high spatiotemporal resolution. The glider was deployed at 129.1 °E in September 18 and conducted 88-days flight from September 19 to December 15 2020, yielding twelve hydrographic sections, and then recovered at 129.2 °E in December 21 after the last 6 days virtual mooring operation. During the total traveled distance of 2550 km, the estimated deviation from the predetermined zonal path had an average RMS distance of 262 m. Based on these high-resolution long-term glider measurements, we conducted a comparative study with the bi-monthly NIFS measurements in terms of spatial and temporal resolutions, and found distinguished features. One is that spatial features of sub-mesoscale such as sub-mesoscale frontal structure and intensified thermocline were detected only in the glider measurements, mainly due to glider's high spatial resolution. The other is the detection of intramonthly variations from the weekly time series of temperature and salinity, which were extracted from glider's continuous sections. Lastly, there were deviations and bias in measurements from both platforms. We argued these deviations in terms of the time scale of variation, the spatial scale of fixed-point observation, and the calibration status of CTD devices of both platforms.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.3
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• pp.427-438
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• 2022

With the recent growing importance over safety management the need for advanced and technical approaches for on-site safety inspection methods has increased. Railway construction is subject to its own particular set of temporal and spatial challenges due to its unique facilities and equipment. This study aimed to investigate the field characteristics of railway infrastructure and improve the conventional field safety management methods by identifying the most appropriate features of AR technology. Group interviews and surveys were conducted with field safety experts to derive the major problems and inspection needs. Subsequently, various features of AR, such as BIM model projection, and remote conferencing, were investigated to determine their applicability to address safety issues. As a result, four problems in the current safety management process, such as 'lack of time due to the conventional inspection method and inspection of areas that are difficult to access', and three major inspection types, such as 'observance of work procedures, status of installation, adequate dimensional spacing', were identified to be improved when adopting AR based techniques. Furthermore, AR technology utilizing plans to solve safety inspection problems and effectively manage major inspection types were proposed, and a follow up survey was conducted with the same field safety experts to derive the priority of technology development.