• Journal of KIISE:Databases
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• v.33 no.4
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• pp.396-408
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• 2006

Moving object databases manage a large amount of past location data which are accumulated as the time goes. To retrieve fast the past location of moving objects, we need index structures which consider features of moving objects. The KDB-tree has a good performance in processing range queries. Although we use the KDB-tree as an index structure for moving object databases, there has an over-split problem in the spatial domain since the feature of moving object databases is to increase the time domain. Because the over-split problem reduces spatial regions in the MBR of nodes inverse proportion to the number of splits, there has a problem that the cost for processing spatial-temporal range queries is increased. In this paper, we propose the dynamic split strategy of the KDB-tree to process efficiently the spatial-temporal range queries. The dynamic split strategy uses the space priority splitting method for choosing the split domain, the recent time splitting policy for splitting a point page to maximize the space utilization, and the last division policy for splitting a region page. We compare the performance of proposed dynamic split strategy with the 3DR-tree, the MV3R-tree, and the KDB-tree. In our performance study for range queries, the number of node access in the MKDB-tree is average 30% less than compared index structures.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.40 no.1
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• pp.51-66
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• 2022

SST (Sea Surface Temperature) is based on the atmosphere-ocean interaction, one of the most important mechanisms for the Earth system. Because it is a crucial oceanic and meteorological factor for understanding climate change, gap-free grid data at a specific spatial and temporal resolution is beneficial in SST studies. This paper examined the production of daily SST grid maps from 137 stations in 2020 through the ordinary kriging with variogram optimization and their accuracy assessment. The variogram optimization was achieved by WLS (Weighted Least Squares) method, and the blind tests for the interpolation accuracy assessment were conducted by an objective and spatially unbiased sampling scheme. The four-round blind tests showed a pretty high accuracy: a root mean square error between 0.995 and 1.035℃ and a correlation coefficient between 0.981 and 0.982. In terms of season, the accuracy in summer was a bit lower, presumably because of the abrupt change in SST affected by the typhoon. The accuracy was better in the far seas than in the near seas. West Sea showed better accuracy than East or South Sea. It is because the semi-enclosed sea in the near seas can have different physical characteristics. The seasonal and regional factors should be considered for accuracy improvement in future work, and the improved SST can be a member of the SST ensemble around South Korea.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.1
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• pp.49-64
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• 2014

Seabed beneath and near the coastal structures may undergo large excess pore water pressure composed of oscillatory and residual components in the case of long durations of high wave loading. This excess pore water pressure may reduce effective stress and, consequently, the seabed may liquefy. If the liquefaction occurs in the seabed, the structure may sink, overturn, and eventually fail. Especially, the seabed liquefaction behavior beneath a gravity-based structure under wave loading should be evaluated and considered for design purpose. In this study, to evaluate the liquefaction potential on the seabed, numerical analysis was conducted using 2-dimensional numerical wave tank. The 2-dimensional numerical wave tank was expanded to account for irregular wave fields, and to calculate the dynamic wave pressure and water particle velocity acting on the seabed and the surface boundary of the structure. The simulation results of the wave pressure and the shear stress induced by water particle velocity were used as inputs to a FLIP(Finite element analysis LIquefaction Program). Then, the FLIP evaluated the time and spatial variations in excess pore water pressure, effective stress and liquefaction potential in the seabed. Additionally, the deformation of the seabed and the displacement of the structure as a function of time were quantitatively evaluated. From the analysis, when the shear stress was considered, the liquefaction at the seabed in front of the structure was identified. Since the liquefied seabed particles have no resistance force, scour can possibly occur on the seabed. Therefore, the strength decrease of the seabed at the front of the structure due to high wave loading for the longer period of time such as a storm can increase the structural motion and consequently influence the stability of the structure.

• Korean Journal of Remote Sensing
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• v.39 no.5_3
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• pp.1031-1042
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• 2023

In this study, a deep learning model was developed to predict the yield of cabbage and radish, one of the five major supply and demand management vegetables, using satellite images of Landsat 8. To predict the yield of cabbage and radish in Gangwon-do from 2015 to 2020, satellite images from June to September, the growing period of cabbage and radish, were used. Normalized difference vegetation index, enhanced vegetation index, lead area index, and land surface temperature were employed in this study as input data for the yield model. Crop yields can be effectively predicted using satellite images because satellites collect continuous spatiotemporal data on the global environment. Based on the model developed previous study, a model designed for input data was proposed in this study. Using time series satellite images, convolutional neural network, a deep learning model, was used to predict crop yield. Landsat 8 provides images every 16 days, but it is difficult to acquire images especially in summer due to the influence of weather such as clouds. As a result, yield prediction was conducted by splitting June to July into one part and August to September into two. Yield prediction was performed using a machine learning approach and reference models , and modeling performance was compared. The model's performance and early predictability were assessed using year-by-year cross-validation and early prediction. The findings of this study could be applied as basic studies to predict the yield of field crops in Korea.

• Korean Journal of Remote Sensing
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• v.18 no.4
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• pp.187-199
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• 2002

Correlation between chlorophyll a in the East China Sea and spectral bands (412, 443, 490, (510), 555, (676, 765)nm) of Ocean Scanning Multi-Spectral Imager (OSMI) including the profile multi-spectral radiometer (PRR-800) was studied. The values of remote sensing reflectance (Rrs) at the bands corresponding to the field chlorophyll $\alpha$ in the East China Sea were much higher than those in clear waters off California, USA. In case of the particle absorptions related to the chlorophyll a concentration at the spectral bands (440, 670nm) were much higher in the East China Sea than the ones in the clean waters off California. The normalized water leaving radiances (nLw) at 412, 443, 490, 555 nm of OSMI and the field chlorophyll a in the East China Sea were correlated each other. According to the results, the relationship between field chlorophyll $\alpha$ and nLw 410 nm in OSMI bands was the lowest, whereas that between field chlorophyll a and nLw 555 nm in the bands was the highest. Reciprocal action between the field chlorophyll a and the band ratio of the OSMI bands (nLw410/nLw555, nLw443/nLw555, nLw490/nLw555) was also studied. Relationship between the chlorophyll $\alpha$ and the band ratio (nLw490/nLw555) was highest in the OSMI bands. Relationship between the chlorophyll $\alpha$ and the ratio (nLw490/nLw555) was higher than one in the nLw410/nLw555. The difference in the estimated chlorophyll $\alpha$ (mg/m$^3$) between OSMI and SeaWiFS (Sea Viewing Wide Field-of-View Sensor) at the special observing stations in the northern eastern sea of Jeju Island in February 25, 2002 was about less than 0.3 mg/m$^3$ within 3 hours. It is suggested that OC2 (ocean color chlorophyll 2 algorithm) be used to get much better estimation of chlorophyll $\alpha$ from OSMI than the ones from the updated algorithms as OC4.

• Economic and Environmental Geology
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• v.53 no.2
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• pp.147-157
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• 2020

Mass change in the Antarctic Ice Sheet(AIS) is the most important indicator of changes in Earth's climate system including global mean sea level rise that are largely affected by ongoing global warming. In this study, AIS mass variations are examined with satellite gravity data and outputs from a regional climate model. The analysis of gravity data shows that along the coastal region the Western AIS has experienced a continuous and significant ice loss while a slight increasing in the Eastern AIS during the study period (2002.08-2016.08). The temporal and spatial variations in ice mass changes are recovered by a regional climate model, but the recovered amplitudes are much smaller than those of observations. This under-estimation is remarkably resolved by modifying a base flow field for the ice discharge. The recovered estimates based on the ice-flow field can explain about 97% of the rate of mass change in observations before 2009. This implies that changes in ice flow dynamics along the coast line plays a pivotal role in regulating long-term budget of ice mass in AIS.

• Korean Journal of Agricultural and Forest Meteorology
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• v.16 no.3
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• pp.157-168
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• 2014

From a complex systems perspective, ecohydrological systems in forests may be characterized with (1) large networks of components which give rise to complex collective behaviors, (2) sophisticated information processing, and (3) adaptation through self-organization and learning processes. In order to demonstrate such characteristics, we applied the recently proposed 'process networks' approach to a temperate deciduous forest in Gwangneung National Arboretum in Korea. The process network analysis clearly delineated the forest ecohydrological systems as the hierarchical networks of information flows and feedback loops with various time scales among different variables. Several subsystems were identified such as synoptic subsystem (SS), atmospheric boundary layer subsystem (ABLS), biophysical subsystem (BPS), and biophysicochemical subsystem (BPCS). These subsystems were assembled/disassembled through the couplings/decouplings of feedback loops to form/deform newly aggregated subsystems (e.g., regional subsystem) - an evidence for self-organizing processes of a complex system. Our results imply that, despite natural and human disturbances, ecosystems grow and develop through self-organization while maintaining dynamic equilibrium, thereby continuously adapting to environmental changes. Ecosystem integrity is preserved when the system's self-organizing processes are preserved, something that happens naturally if we maintain the context for self-organization. From this perspective, the process networks approach makes sense.

• Cross-Cultural Studies
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• v.42
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• pp.419-449
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• 2016

The Russian icon and Korean tangwha (幀畵, altar portrait of Buddha) are based on the similarity of the divine Being. Each has the characteristic index that forms an existential connection with the object and at the same time, implies the symbolic meaning of the scriptures and doctrines of the Russian Orthodox and Buddhists. Russian icon and Korean tangwha with these attributes have origins in the Byzantine, India and China. Unlike most religious art, Russian icon and Korean tangwha clearly reveal profane orientation and mystical elements. This artistic phenomenon has evolved from the mystical religious culture in Russia and tantric rituals of the early Joseon period. Iconostasis, created from historical figures of the Old Testament, Jesus, the New Testament represent the principles of the macrocosm. Each icon of iconostasis has integrity, while each floor has another narrative and a meta-discourse on the entire composition. Three-Platforms of amrtakundalin can also have a huge epic that is directed from the Low-Platform to the High-Platform for the purpose of salvation. While the narrative of iconostasis has a time structure, from the beginning of the universe up to date in chronological time, amrtakundalin have pictorial transitions of time and space that rises from this life to a heavenly world. Despite the different world views of the Russian Orthodox and Buddhists, iconographical format and symbolism of heaven and hell in the Iconostasis, Last Judgment and amrtakundalin are similar. There is a constant antagonism between heaven and hell, light and darkness, water and flame. Iconographical contents include the water of life and nectar, the book of life and 'eoppu', and the scales and mirror of Karma that discriminate between the good and evil before judgment. The dualistic coordinate concept such as light and darkness, life and death, or heaven and hell that appears in the narrative structure of iconostasis, the Last Judgment and amrtakundalin leads the people to spiritual awakening.

• The Journal of the Korea Contents Association
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• v.21 no.6
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• pp.687-700
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• 2021

The advent of realistic technologies such as AR has extended the interaction area from the computer environment to the offline space. As demand is expected to increase in the future, the need for study on interactive storytelling that mediates online and offline is emerging. This study proposes a storytelling structure to achieve a balance between interactivity and narrativity in interactive narrative characterized by online and offline mediation. According to a case study of ARG and AR games based on Henry Jenkins' theory of 'Environmental Storytelling', there should be a balance between the space designed by the game designer and the space created by the player's interaction, and the roles should be properly distributed in both online and offline spaces to contribute to the formation of narrative together. In addition, it is necessary to borrow the characteristics of ARG that achieves a balance of interactivity and narrativity based on offline spatiality. The significance of this study is to expand the area of interactive storytelling, which has been discussed centering on online, to offline, and to suggest the interaction area as a factor to consider. In addition, as a basic study related to storytelling that mediates online and offline, it is expected to provide a direction for the development of content based on realistic technologies.

• Journal of Service Research and Studies
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• v.11 no.2
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• pp.1-19
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• 2021

This study was conducted to derive a model of a sustainable politics and administration system that will enhance human happiness. A new long-term sustainable development model has been established based on the experience of the politics and administration system over the past thousands of years. Currently, the democratic political system and the bureaucratic administrative system dominate, but they are facing many problems. In this study, we analyzed the politics and administration system experienced by human society, and derived a model of a politics and administration system that is ideal for the present and future societies and is sustainable in the long term. The necessary condition should be a model that can solve the problems of the current politics and administration system. It must be a model that is faithful to the characteristics and essence of modern society. And as a sufficient condition to ensure long-term sustainability, it must be based on the common principles of human society. After analyzing the problems of the current system and analyzing the conditions required for the new system, the axioms that are the basis of the politics and administration system were presented. Based on the axioms, the structure and operation model of a new politics and administration system were derived. The derived model was named as a servicism politics and administration system. It is a dynamic model in which two opposing opponents recognize each other's contradictions and balance them dialectically in the space-time dimension.