• Journal of fish pathology
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• v.22 no.3
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• pp.283-291
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• 2009

This study was conducted to evaluate the effects of a commercial extruded pellet (EP) and raw fish moist pellet (MP) diet on disease prevalence and serum chemistry of olive flounder Paralichthys olivaceus grown in two commercial-scale aquaculture farms from July to December in 2008. The contents of serum GOT, GPT and glucose in fish fed EP diet (EP group) were higher than those of fish fed the MP diet (MP group). There were no distinct differences in survival rates and mean detection rates of fish pathogens among fish group fed the experimental diets. However, the mean detection rate of fish pathogens in MP group was higher than that of EP group from July to October which are high water temperature season. The dominant pathogens isolated in EP group were Dactylogyrus sp., E. tarda and red sea bream iridovirus (RSIV). On the other hand, Trichodina sp., Streptococcus spp., viral nervous necrosis virus (VNNV) were dominant in MP group.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.4
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• pp.245-257
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• 2023

The representative crop in the Republic of Korea, rice, is cultivated over extensive areas every year, which resulting in reduced resistance to pests and diseases. One of the major rice diseases, rice blast disease, can lead to a significant decrease in yields when it occurs on a large scale, necessitating early detection and effective control of rice blast disease. Drone-based crop monitoring techniques are valuable for detecting abnormal growth, but frequent image capture for potential rice blast disease occurrences can consume significant labor and resources. The purpose of this study is to early detect rice blast disease using remote sensing data, such as drone and satellite images, along with weather data. Satellite images was helpful in identifying rice cultivation fields. Effective detection of paddy fields was achieved by utilizing vegetation and water indices. Subsequently, air temperature, relative humidity, and number of rainy days were used to calculate the risk of rice blast disease occurrence. An increase in the risk of disease occurrence implies a higher likelihood of disease development, and drone measurements perform at this time. Spectral reflectance changes in the red and near-infrared wavelength regions were observed at the locations where rice blast disease occurred. Clusters with low vegetation index values were observed at locations where rice blast disease occurred, and the time series data for drone images allowed for tracking the spread of the disease from these points. Finally, drone images captured before harvesting was used to generate spatial information on the incidence of rice blast disease in each field.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.7
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• pp.697-703
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• 2006

Endocrine disruptors were measured with GC/MS in effluents discharged from sewage treatment processes in pilot scale for the purpose of water reuse. From that analysis, we compared the removal rate of them by treatment processes. Nonylphenol was mainly detected in effluents and high concentration from 0.36 to 0.94 ${\mu}g/L$. $17{\beta}$-estradiol(E2) and $17{\alpha}$-ethynylestradiol(EE2) were detected as below the limit of detection in effluent. Endocrine disruptors were removed effectively in the range from 50 to 100% by treatment process. EC50 value($9.0{\times}10^{-3}$ M) of $17{\beta}$-estradiol(E2) by dose response curve of E-screen assay has higher than that of bisphenol A($2.736{\times}10^{-5}M$) and p-octylphenol($9.760{\times}10^{-6}$ M). These results showed that alkylphenols have lower relative estrogen potency than other estrogens such as $17{\beta}$-estradiol(E2). Calculated estrogenic activity(ng-EEQ/L) was 2 times higher than measured total estrogenic activity which estimated by E-screen assay. Moreover estrogenic activity of effluent by treatment process showed very low as below 1 ng-EEQ/L.

• Journal of the Korean Society of Groundwater Environment
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• v.3 no.1
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• pp.27-36
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• 1996

The Nanji landfill is one of the biggest uncontrolled landfill in terms of its size and scale in the world. Because the landfill was constructed on the very vulnerable alluvial deposit installing no pollution control systems such as bottom liner and leachate collection systems, it has caused a serious adverse effect to near-by groundwater and surface water systems. A through remedial investigation comprising plume detection and site-characterization was performed to design the remedial measure. As a part the investigation, comprehensive water quality study was conducted, using ten existing observation wells and one bundle type monitoring well, to determine the contaminant indicators for the plume delineation and to define the vertical and horizontal variation of specific contaminants via distances from the landfill. The results clearly shows that EC and temperature are a good pollution indicators and the vertical concentrations of specific contaminants measured in the fully screened wells are 20 to 90% more than those measured at the same depth in bundle type well which is located just 2 m apart. This paper presents a cost effective monitoring and sampling method to define the contaminant plume and obtain a basic data for leachate control measures.

• Korean Journal of Remote Sensing
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• v.40 no.2
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• pp.203-217
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• 2024

The Land Use, Land-Use Change and Forestry (LULUCF) sector of the National Greenhouse Gas Inventory is crucial for obtaining data on carbon sinks, necessitating accurate estimations. This study analyzes cases of countries applying the LULUCF sector at the Tier 3 level to propose enhanced methodologies for carbon sink estimation. In nations like Japan and Western Europe, satellite spatial information such as SPOT, Landsat, and Light Detection and Ranging (LiDAR)is used alongside national statistical data to estimate LULUCF. However, in Korea, the lack of land use change data and the absence of integrated management by category, measurement is predominantly conducted at the Tier 1 level, except for certain forest areas. In this study, Space-borne LiDAR Global Ecosystem Dynamics Investigation (GEDI) was used to calculate forest canopy heights based on Relative Height 100 (RH100) in the cities of Icheon, Gwangju, and Yeoju in Gyeonggi Province, Korea. These canopy heights were compared with the 1:5,000 scale forest maps used for the National Inventory Report in Korea. The GEDI data showed a maximum canopy height of 29.44 meters (m) in Gwangju, contrasting with the forest type maps that reported heights up to 34 m in Gwangju and parts of Icheon, and a minimum of 2 m in Icheon. Additionally, this study utilized Ordinary Least Squares(OLS)regression analysis to compare GEDI RH100 data with forest stand heights at the eup-myeon-dong level using ArcGIS, revealing Standard Deviations (SDs)ranging from -1.4 to 2.5, indicating significant regional variability. Areas where forest stand heights were higher than GEDI measurements showed greater variability, whereas locations with lower tree heights from forest type maps demonstrated lower SDs. The discrepancies between GEDI and actual measurements suggest the potential for improving height estimations through the application of high-resolution remote sensing techniques. To enhance future assessments of forest biomass and carbon storage at the Tier 3 level, high-resolution, reliable data are essential. These findings underscore the urgent need for integrating high-resolution, spatially explicit LiDAR data to enhance the accuracy of carbon sink calculations in Korea.

• The Journal of Engineering Geology
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• v.28 no.1
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• pp.69-79
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• 2018

The Korean government attempts to reduce $CO_2$ emissions by 37% to 314.7 Mt $CO_2$, down from the estimated 850.6 Mt $CO_2$ until 2030 in order to confront green house effect. In this context, in 2014, Korean government launched $CO_2$ Storage Environmental Management Research (K-COSEM) Center for carrying out pilot-scale research on $CO_2$ leakage from underground $CO_2$ storage facilities. For the detection of $CO_2$ leakage, it is necessary to identify hydrologeological and geophysical characteristics of the subject area. In the study site of Naesan-ri, Daeso-myeon, Eumseong-gun, Chungbuk Province, two times injection tests (June 28-July 24, 2017 and August 07-September 11, 2017) of $CO_2$ and $SF_6$ dissolved waters, respectively, was conducted to understand the leakage behavior of $CO_2$ from underground. The injection well was drilled to a depth of 24 m with a 21-m casing and screen interval of 21~24 m depth. Two times resistivity surveys on August 18, 2017 and September 1, 2017, were conducted for revealing the flow of the injected water as well as the electrical properties of the study site. The study results have shown that the high-resistivity zone and the low-resistivity zone are clearly contrasted with each other and the flow direction of the injected water is similar to natural groundwater flow. Besides, the low resistivity zone is widely formed from the depth of injection to the shallow topsoil, indicating that the weathered zone of high permeability has high $CO_2$ leakage potential.

• Korean Journal of Remote Sensing
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• v.33 no.5_3
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• pp.855-866
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• 2017

Several research cases using remote sensing methods to analyze changes of storage and dynamics of groundwater aquifer were reviewed in this paper. The status of groundwater storage, in an area with regional scale, could be qualitatively inferred from geological feature, surface water altimetry and topography, distribution of vegetation, and difference between precipitation and evapotranspiration. These qualitative indicators could be measured by geological lineament analysis, airborne magnetic survey, DEM analysis, LAI and NDVI calculation, and surface energy balance modeling. It is certain that GRACE and InSAR have received remarkable attentions as direct utilization from satellite data for quantification of groundwater storage and dynamics. GRACE, composed of twin satellites having acceleration sensors, could detect global or regional microgravity changes and transform them into mass changes of water on surface and inside of the Earth. Numerous studies in terms of groundwater storage using GRACE sensor data were performed with several merits such that (1) there is no requirement of sensor data, (2) auxiliary data for quantification of groundwater can be entirely obtained from another satellite sensors, and (3) algorithms for processing measured data have continuously progressed from designated data management center. The limitations of GRACE for groundwater storage measurement could be defined as follows: (1) In an area with small scale, mass change quantification of groundwater might be inaccurate due to detection limit of the acceleration sensor, and (2) the results would be overestimated in case of combination between sensor and field survey data. InSAR can quantify the dynamic characteristics of aquifer by measuring vertical micro displacement, using linear proportional relation between groundwater head and vertical surface movement. However, InSAR data might now constrain their application to arid or semi-arid area whose land cover appear to be simple, and are hard to apply to the area with the anticipation of loss of coherence with surface. Development of GRACE and InSAR sensor data preprocessing algorithms optimized to topography, geology, and natural conditions of Korea should be prioritized to regionally quantify the mass change and dynamics of the groundwater resources of Korea.

• Korean Journal of Remote Sensing
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• v.30 no.1
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• pp.83-107
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• 2014

This study presents spatial characteristics of cloud using satellite image in the extreme heavy snowfall of the Yeongdong region. 3 extreme heavy snowfall events in the Yeongdong region during the recent 12 years (2001 ~ 2012) are selected for which the fresh snow cover exceed 50 cm/day. Spatial characteristics (minimum brightness temperature; Tmin, cloud size, center of cloud-cell) of cloud are analyzed by tracking main cloud-cell related with these events. These characteristics are compared with radar precipitation in the Yeongdong region to investigate relationship between cloud and precipitation. The results are summarized as follows, selected extreme heavy snowfall events are associated with the isolated, well-developed, and small-scale convective cloud which is developing over the Yeongdong region or moving from over East Korea Bay to the Yeongdong region. During the period of main precipitation, cloud-cell Tmin is low ($-40{\sim}-50^{\circ}C$) and cloud area is small (17,000 ~ 40,000 $km^2$). Precipitation area (${\geq}$ 0.5 mm/hr) from radar also shows small and isolated shape (4,000 ~ 8,000 $km^2$). The locations of the cloud and precipitation are similar, but in there centers are located closely to the coast of the Yeongdong region. In all events the extreme heavy snowfall occur in the period a developed cloud-cell was moving into the coastal waters of the Yeongdong. However, it was found that developing stage of cloud and precipitation are not well matched each other in one of 3 events. Water vapor image shows that cloud-cell is developed on the northern edge of the dry(dark) region. Therefore, at the result analyzed from cloud and precipitation, selected extreme heavy snowfall events are associated with small-scale secondary cyclone or vortex, not explosive polar low. Detection and tracking small-scale cloud-cell in the real-time forecasting of the Yeongdong extreme heavy snowfall is important.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.115-116
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• 2012

The demand for flexible electronic systems such as wearable computers, E-paper, and flexible displays has increased due to their advantages of excellent portability, conformal contact with curved surfaces, light weight, and human friendly interfaces over present rigid electronic systems. This seminar introduces three recent progresses that can extend the application of high performance flexible inorganic electronics. The first part of this seminar will introduce a RRAM with a one transistor-one memristor (1T-1M) arrays on flexible substrates. Flexible memory is an essential part of electronics for data processing, storage, and radio frequency (RF) communication and thus a key element to realize such flexible electronic systems. Although several emerging memory technologies, including resistive switching memory, have been proposed, the cell-to-cell interference issue has to be overcome for flexible and high performance nonvolatile memory applications. The cell-to-cell interference between neighbouring memory cells occurs due to leakage current paths through adjacent low resistance state cells and induces not only unnecessary power consumption but also a misreading problem, a fatal obstacle in memory operation. To fabricate a fully functional flexible memory and prevent these unwanted effects, we integrated high performance flexible single crystal silicon transistors with an amorphous titanium oxide (a-TiO2) based memristor to control the logic state of memory. The $8{\times}8$ NOR type 1T-1M RRAM demonstrated the first random access memory operation on flexible substrates by controlling each memory unit cell independently. The second part of the seminar will discuss the flexible GaN LED on LCP substrates for implantable biosensor. Inorganic III-V light emitting diodes (LEDs) have superior characteristics, such as long-term stability, high efficiency, and strong brightness compared to conventional incandescent lamps and OLED. However, due to the brittle property of bulk inorganic semiconductor materials, III-V LED limits its applications in the field of high performance flexible electronics. This seminar introduces the first flexible and implantable GaN LED on plastic substrates that is transferred from bulk GaN on Si substrates. The superb properties of the flexible GaN thin film in terms of its wide band gap and high efficiency enable the dramatic extension of not only consumer electronic applications but also the biosensing scale. The flexible white LEDs are demonstrated for the feasibility of using a white light source for future flexible BLU devices. Finally a water-resist and a biocompatible PTFE-coated flexible LED biosensor can detect PSA at a detection limit of 1 ng/mL. These results show that the nitride-based flexible LED can be used as the future flexible display technology and a type of implantable LED biosensor for a therapy tool. The final part of this seminar will introduce a highly efficient and printable BaTiO3 thin film nanogenerator on plastic substrates. Energy harvesting technologies converting external biomechanical energy sources (such as heart beat, blood flow, muscle stretching and animal movements) into electrical energy is recently a highly demanding issue in the materials science community. Herein, we describe procedure suitable for generating and printing a lead-free microstructured BaTiO3 thin film nanogenerator on plastic substrates to overcome limitations appeared in conventional flexible ferroelectric devices. Flexible BaTiO3 thin film nanogenerator was fabricated and the piezoelectric properties and mechanically stability of ferroelectric devices were characterized. From the results, we demonstrate the highly efficient and stable performance of BaTiO3 thin film nanogenerator.

• Journal of Nutrition and Health
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• v.49 no.2
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• pp.88-98
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• 2016

Purpose: We recruited 118 women in their early 20's to examine the relationship between sodium intake and salty taste thresholds and preference. We also examined the association of salty taste preference with sodium-related dietary behaviors and major dishes contributing to sodium intake. Methods: Daily sodium intake was estimated using a 127-item dish-frequency questionnaire. Salty taste thresholds and preference were measured using rating scales using water solution of NaCl and a self-administered questionnaire based on a Likert scale, respectively. Results: Salty taste preference showed positive correlation with daily sodium intake and sodium intake-increasing behaviors, and inverse association with sodium intake-decreasing behaviors, including salt and soy sauce use at the table, the frequency of eating out and home delivery of foods, broth consumption of soup, stew or noodle soup, the use of ready-to-serve or processed foods, fresh vegetable intake, and the accommodating attitude toward bland food. Intake of sodium-contributing dishes, including ramen, spicy soft-tofu stew, radish kimchi, and dishes containing kimchi, also showed positive association with salty taste preference. Unexpectedly, detection and recognition thresholds of salty taste showed no association with salty taste preference, sodium intake, and sodium-related dietary behaviors. Conclusion: These findings suggest that salty taste preference could reflect sodium intake of individuals rather than thresholds of saltiness, and may be used as a simple and effective proxy for usual sodium intake.