• Korean Journal of Remote Sensing
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• v.19 no.2
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• pp.117-133
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• 2003

A field survey and Landsat ETM+ image acquisition carried out simultaneously. Using these data, we attempted to establish relationships between tidal flat environmental factors and reflectance observed by ETM+, and to set up a new critical grain size useful for optical remote sensing. Although the grain size of 4 $\Phi$ has been conventionally used as a critical size by sedimentologists, the correlation with optical reflectance was very low. Instead, the grain size of 2 $\Phi$ showed a relatively high correlation coefficient, 0.699, with ETM+ band 4, except near tidal channels in upper tidal flat. We concluded that the grain size of 2 $\Phi$ would be better to use for a critical grain size in Gomso Bay. The grain size also correlated well with moisture content having a correlation coefficient of -0.811 when the 2 $\Phi$ criterion was used. The results of factor analysis showed moisture content was more important parameter than topographic relief, and they were different from German tidal flats in which topographic relief was the prior factor This can be explained by finer grain composition of the Gomso bay tidal flat. In short, moisture content and topography as well as grain size should be considered in tidal flat remote sensing.

• The Journal of the Acoustical Society of Korea
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• v.38 no.4
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• pp.378-386
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• 2019

Unlike ship noise that radiates from moving ships, wind noise is caused by breaking waves as a result of the interaction between the wind and the sea surface. In this paper, WNL (Wind Noise Level) was modeled by considering the noise source of the wind as the bubble cloud generated by the breaking waves. In the modeling, SL( Source Level) of the wind noise was calculated using the wind-speed data measured from the weather buoy operated in the coastal area of the East Sea. At the same time as observing the wind speed, NL (Noise Level) was continuously measured using a self-recording hydrophone deployed near the weather buoy. The modeled WNL according to the wind speed and the measured NL removing the shipping noise from the acoustic raw data were compared in the low-frequency band. The overall trends between the modeled WNL and the measured NL were similar to each other. Therefore, it was confirmed that it is possible to model the WNL in the shallow water considering the SL and distribution depth of bubble cloud caused by the wind.

• Economic and Environmental Geology
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• v.54 no.1
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• pp.127-136
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• 2021

This study was carried out to understand China's earthquake governance and role-sharing, and to strategically use it for research cooperation in related fields with China. The characteristics of China's national earthquake governance and role-sharing are detailed in this study. First, unlike Korea, China's geoscience and earthquake research fields are separate, and are clearly distinguished from other fields of science and technology. They hold a higher status compared to other fields in China. Second, China's provincial earthquake agencies simultaneously carry out related tasks under the dual supervisory management system of the central and provincial governments. Third, the China Earthquake Administration (CEA) has the authority to do research and development, manpower training, and degree conferment, which are centered on directly affiliated institutions. Fourth, China carries out similar functions in directly affiliated institutions of the CEA and the China Geological Survey (CGS), and affiliated institutions of the Chinese Academy of Sciences (CAS), respectively. Fifth, the CEA is continuously expanding the seismic observation network that connects the vast land of the country. Sixth, China is considered to have detailed structures of earthquake-related laws and regulations. Given China's earthquake governance and role-sharing, it is considered that the possibility of success in research cooperation is high if Korea first determines whether it is under the jurisdiction of the CGS, CEA, and CAS, depending on the specific field.

• Journal of the Korean earth science society
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• v.41 no.6
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• pp.599-616
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• 2020

Sea-surface temperature (SST) is one of the most important oceanic variables for understanding air-sea interactions, heat flux variations, and oceanic circulation in the global ocean. Extremely low SSTs from 0℃ down to -2℃ should be more important than other normal temperatures because of their notable roles in inducing and regulating global climate and environmental changes. To understand the temporal and spatial variability of such extremely low SSTs in the global ocean, the long-term SST climatology was calculated using the daily SST database of satellites observed for the period from 1982 to 2018. In addition, the locations of regions with extremely low surface temperatures of less than 0℃ and monthly variations of isothermal lines of 0℃ were investigated using World Ocean Atlas (WOA) climatology based on in-situ oceanic measurements. As a result, extremely low temperatures occupied considerable areas in polar regions such as the Arctic Ocean and Antarctic Ocean, and marginal seas at high latitudes. Six earth science textbooks were analyzed to investigate how these extremely low temperatures were visualized. In most textbooks, illustrations of SSTs began not from extremely low temperatures below 0℃ but from a relatively high temperature of 0℃ or higher, which prevented students from understanding of concepts and roles of the low SSTs. As data visualization is one of the key elements of data literacy, illustrations of the textbooks should be improved to ensure that SST data are adequately visualized in the textbooks. This study emphasized that oceanic literacy and data literacy could be cultivated and strengthened simultaneously through visualizations of oceanic big data by using satellite SST data and oceanic in-situ measurements.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.296-301
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• 2021

GPR is used for non-destructive investigations, ground investigations, and underground facilities exploration at construction sites. In this study, the applicability to GPR exploration of water pipes linked to Network RTK was presented. Data on the water supply pipes in the study site were acquired using GPR, and the location and depth of buried water pipes could be measured. The accuracy was evaluated from the GNSS observation performance and showed a deviation of -0.16m ~ 0.15m. This satisfied the equipment performance of the public survey work regulation, suggesting that the exploration of water pipes using GPR is possible. Because GPR does not require grounding installation, as in conventional metal pipe detectors, it will increase the efficiency of work for underground facility exploration. Exploration using GPR can acquire the location and depth of metallic and non-metallic underground facilities, so it can be utilized in the construction of a GIS system. If a comparison of the exploration characteristics is carried out, it will be possible to present various uses of underground facility exploration using GPR.

• Journal of Korea Water Resources Association
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• v.55 no.12
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• pp.1137-1147
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• 2022

River and groundwater stages are the main elements in the hydrologic cycle. They are spatially correlated and can be used to evaluate hydrological and agricultural drought. Stochastic simulation is often performed independently on hydrological variables that are spatiotemporally correlated. In this setting, interdependency across mutual variables may not be maintained. This study proposes the Bayesian vector autoregression model (VAR) to capture the interdependency between multiple variables over time. VAR models systematically consider the lagged stages of each variable and the lagged values of the other variables. Further, an autoregressive model (AR) was built and compared with the VAR model. It was confirmed that the VAR model was more effective in reproducing observed interdependency (or cross-correlation) between river and ground stages, while the AR generally underestimated that of the observed.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.spc
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• pp.1-10
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• 2022

As the volume of marine hazardous and noxious substances (HNSs) transported in domestic and overseas seas increases, the risk of HNS spill accidents is gradually increasing. HNS leaked into the sea causes destruction of marine ecosystems, pollution of the marine environment, and human casualties. Secondary accidents accompanied by fire and explosion are possible. Therefore, various types of HNSs must be rapidly detected, and a control strategy suitable for the characteristics of each substance must be established. In this study, the ground HNS spill experiment process and application result of detection algorithms were presented based on hyperspectral remote sensing. For this, styrene was spilled in an outdoor pool in Brest, France, and simultaneous observation was performed through a hyperspectral sensor. Pure styrene and seawater spectra were extracted by applying principal component analysis (PCA) and the N-Findr method. In addition, pixels in hyperspectral image were classified with styrene and seawater by applying spectral matching techniques such as spectral distance similarity (SDS), spectral correlation similarity (SCS), spectral similarity value (SSV), and spectral angle mapper (SAM). As a result, the SDS and SSV techniques showed good styrene detection results, and the total extent of styrene was estimated to be approximately 1.03 m². The study is expected to play a major role in marine HNS monitoring.

• Journal of the Korean Chemical Society
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• v.67 no.3
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• pp.191-198
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• 2023

Acyl transfer reactions of 2,4-dinitrophenyl-5-substituted-2-furoates (1a-d) promoted by R₂NH/R₂NH₂⁺ in 20mol% DMSO(aq) have been studied kinetically. The reactions are second-order and exhibit downward curves of the Brönsted plots with pK_a⁰ = 9.5, β₁ = 0.23-0.35 and β₂ = 0.88-0.99. The k₁ values increased with a stronger nucleophile and as the electron-withdrawing ability of the 5-furyl substituent increases. In contrast, the k₂/k_-1 values were nearly idential regardless of the 5-furyl substituents. From these results, a stepwise mechanism with a change in the rate-determining step(RDS) is proposed.

• Journal of the Korean Association of Geographic Information Studies
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• v.26 no.1
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• pp.56-68
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• 2023

A system that extracts seabed topographic information by simultaneously and continuously observing the horizontal position and water depth in the sea by combining a single beam echosounder and GNSS was constructed. By applying the developed system to actual measurements of small-scale sea areas, the effectiveness of bathymetry and sea-floor topographic data acquisition using GNSS and echosounder was examined. By using the developed outdoor program DS-NAV and indoor program DS-CAD and applying the tide level data at the time of actual measurement of the target sea area, it was possible to derive bathymetry results based on the datum level i.e. approximate lowest low water level(A.L.L.W). By using the developed outdoor program DS-NAV and indoor program DS-CAD and applying the tide level data at the time of actual measurement of the target sea area, it was possible to derive the results of bathymetric survey based on the datum level. From database built through the actual measurement. it was possible to create 3D model of the sea-floor topography and extract cross-sections. The results of this study are expected to be economically useful for extracting seabed topographical information from small sea areas or in dredging sites for offshore construction.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.3
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• pp.218-225
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• 2023

An agrivoltaic system (AVS) is a combined system that generates power through photovoltaic panels (PVPs) installed above a field where a crop is cultivated. Although soil moisture is an important limiting factor for open-field crop production, particularly during spring season in Korea, it is not well considered in the utilization of AVS. Indeed, the application of water-energy-food nexus on the AVS should be necessary. In this study, the changes of soil moisture and temperature under the AVS was investigated in fallow paddy field during spring season. The AVS that has partial shading condition by PV panels was decreased soil temperature and increased soil moisture compared to open-field. Furthermore, the maximum of the change in soil moisture to the change in soil temperature had a negative correlation both on open-field and AVS under wet condition. It represents that the micro-climate under the AVS is in energy-limited condition. The open-field of relatively high soil temperature was in water-limited condition. The different behavior of soil moisture on the AVS should be considered for the sustainable agricultural system as related to water-energy-food nexus.