• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.1399-1401
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• 2010

본 연구는 새만금과 새만금 주변에서 Geosensor 스트림 데이터 측정을 위해 대기관련 센서들로 3개의 클러스터를 구성하고, 수질관련 센서들로 하나의 클러스터를 구성하여 Geosensor 네트워크를 구축하였다. 각 클러스터로부터 5분 단위로 수집된 센서 스트림 데이터를 시스템에 전송하고, 시스템에서는 수신된 스트림 데이터를 분석 및 처리하여 DB에 저장한다. 본 연구에서는 Geosensor 데이터 가공 처리 및 저장, Geosensor 관리, 상황정보 관리, Geosensor 스트림 데이터와 GIS 연동 기능을 포함한 시스템을 개발하고자 한다.

• Korean Journal of Agricultural and Forest Meteorology
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• v.15 no.4
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• pp.210-218
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• 2013

The sea breeze shows different characteristics compared to land breeze, such as high wind speed and more rapider shift period. One of the major factors affecting plant early growth is wind speed. In the early growth stage, tree growth-rates rise with decreasing wind speed. Thus, the study was performed to identify wind break effects on wind characteristics and tree growth. The wind break used in this study was about 130 meters length and 3 meters height, made up with poly-ethylene (with 40% openness). We installed one vane and fifteen anemographs at three different heights (1, 2 and 3 meters) on the inner and outer wind break areas. The wind characteristic and plant growth data were collected from Jun. 2011 to Oct. over 2012. The wind rose of the Saemangum seawall area presented the north (21.5%) and it was followed by north-west (18.1%), east (14.9%) and north-east (13.7%) and the remainder with other directions. Wind speeds at height were different. The tree height was 159.6 cm at inside and 129.6 cm at outside. The diameter at root-collar was 36.9 mm at inside and 32.6 mm at outside from wind break.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.734-738
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• 2002

We present spectral characteristics of tidal flat sediments and algal mat that were tested in the Gomso and Saemangum tidal flats, Korea. The objective of this study is to investigate the spectral reflectance and the radar scattering modeling in the tidal flats. Ground truth data obtained in the tidal flats include grain size, soil moisture content and its variation with time, surface roughness, chlorophyll, ground leveling, and field spectral reflectance measurement. The concept of an effective exposed area (EEA) is introduced to accommodate the effect of remnant surface water, and it seriously affects the reflection of short wavelength infrared and microwave. The nin size of 0.0625 mm has been normally used as a critical size of mud and sand discrimination. But we propose here that 0.25 mm is more practical grain size criterion to discriminate by remote sensing. Algal mat is the primary product in tidal flats, and it is found to be very important to understand spectral characteristics for tidal flat remote sensing. We have also conducted radar scattering modeling, and showed L-band HV-polarization would be the most effective combination.

• Journal of Korean Society on Water Environment
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• v.28 no.1
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• pp.26-37
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• 2012

Multi-dimensional hydrodynamic and water quality models are widely used to simulate the physical and biogeochemical processes in the surface water systems such as reservoirs and estuaries. Most of the models have adopted the Eulerian grid modeling framework, mainly because it can reasonably simulate physical dynamics and chemical species concentrations throughout the entire model domain. Determining the optimum grid cell size is important when using the Eulerian grid-based three-dimensional water quality models because the characteristics of species are assumed uniform in each of the grid cells and chemical species are represented by concentration (mass per volume). The objective of this study was to examine the effect of grid-size of a three dimensional hydrodynamic and water quality model (EFDC) on hydrodynamics and mass transport in the Saemangeum Reservoir. Three grid resolutions, respectively representing coarse (CG), medium (MG), and fine (FG) grid cell sizes, were used for a sensitivity analysis. The simulation results of numerical tracer showed that the grid resolution affects on the flow path, mass transport, and mixing zone of upstream inflow, and results in a bias of temporal and spatial distribution of the tracer. With the CG, in particular, the model overestimates diffusion in the mixing zone, and fails to identify the gradient of concentrations between the inflow and the ambient water.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.4
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• pp.65-71
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• 2012

The objective of this study was to estimate surface runoff from rice paddy plots using an artificial neural network (ANN). A field experiment with three treatment levels was conducted in the NICS saemangum experimental field located in Iksan, Korea. The ANN model with the optimal network architectures, named Paddy1901 with 19 input nodes, 1 hidden layer with 16 neurons nodes, and 1 output node, was adopted to predict surface runoff from the plots. The model consisted of 7 parameters of precipitation, irrigation rate, ponding depth, average temperature, relative humidity, wind speed, and solar radiation on the daily basis. Daily runoff, as the target simulation value, was computed using a water balance equation. The field data collected in 2011 were used for training and validation of the model. The model was trained based on the error back propagation algorithm with sigmoid activation function. Simulation results for the independent training and testing data series showed that the model can perform well in simulating surface runoff from the study plots. The developed model has a main advantage that there is no requirement for any prior assumptions regarding the processes involved. ANN model thus can be a good tool to predict surface runoff from rice paddy fields.

• Hwankyungkyoyuk
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• v.17 no.1
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• pp.101-111
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• 2004

The selection rates of Environmental subject have been increasing since the environmental subject was made. Although the quantitative growth, environmental subject is not acknowledged yet in many schools in Korea. Most of environmental teachers teach two subjects; main subject on their own major and environmental subject. In this respect, this qualitative case study aims to show the influence of teachers' charge on environmental class or environmental subject. In the case study, Teacher 'A' takes charge one subject; Environmet, and teacher 'B' takes charge two subjects; Social Study and Environment. Teacher 'A' took some current issues such as SARS(Severe Acute Respiratory Syndrome) and Saemangum project, and uses various instructional methods and instruments. On the other hand, teacher 'B' might not choose the current issues, or usually gives up various instructional methods and instruments because of lack of time. Although they have those differences on the instruction, the teachers 'A' and 'B' both agreed to the importance of Environmental Education as well as they did their best to prepare for class on environmental subject. As a result, all these outcomes show teachers need to be responsible for single subject on environment as teachers' interests seriously affect to environmental subject and class.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.1
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• pp.53-58
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• 2007

In an estuary, mixing and transport of contaminant sometimes occurs in the salt finger favorable condition (Hwang ang Rehmann, 2004). Linearized theory is applied to predict flow dynamics in salt finger favorable condition. The simulated results match well with previous laboratory experiments. When the density ratio is larger than 2, the heat and salt system shows $0.55{\sim}0.57$ as Turner (1967) found, and the salt and sugar system produces 0.87 of Griffiths (1980). As the ratio of molecular diffusivities of two scalars increases, the flux ratio increases. The flux and eddy diffusivity ratios decrease with increase of density ratio, and it takes longer time for flux ratio to be steady state at the higher density ratios.

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.3
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• pp.74-83
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• 1994

A series of isotropic consolidation tests, undrained and drained triaxial compression tests was carried out to investigate the physical characteristics and behaviours of marine silty sands collected from the western coast of Korea. This study also included a theoretical development of the constitutive equation to evaluate stress-strain relationship and volume change of silty sands. The results and main conclusions of the study are summarized as follows; 1. Isotropic compression and swelling index are linearly decreased with an increase in relative density. 2. Both undrained shear strengh and elastic modulus are increased with an increase in relative density and confining pressure. 3. Internal friction angles obtained from drained and undrained compression tests of the soils are proportional to relative density. 4. The phenomenon of dilatancy of each sample is less profound when confining stress is increased but more profound when relative density is increased. 5. The slope of critical state lines is 1.78 for Saemangum, 1.70 for Siewha and 1.26 for Sukmoon sands. 6. In this study, Drucker-Praper type criterion is used and hardening function of Cap model is modified by hyperbolic fuction. This will improve a lack of physical meaning of hardening parameters in conventional Cap model. 7. A newly developed constitutive equation to the forementioned silty sands and checked its applicability. This is in good agreement with the measured data.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.5
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• pp.373-378
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• 2013

Information on the effective application method of arbuscular mycorrhizal fungi (AMF) inoculum is still inadequate. This work was performed to assess two AMF inoculation methods (dispersed and proximate) on root colonization of sorghum-sudangrass hybrid (Sorghum bicolor L.). In dispersed inoculation method, spores were inoculated in 2 kg pots of soil in which 5 day-old seedlings were transplanted and maintained for 50 days. In the proximate inoculation method, spores were first introduced in 500 mL pots where seeds were sown. After 10 days, the seedlings with the 500 mL soil were transferred to 2 kg pots without disturbing the contents. After 50 days of growth, root colonization and arbuscule abundance significantly increased (over 100%) in proximate method of inoculation. Moreover, sorghum-sudangrass hybrid had higher shoot growth (182.5 cm) and Glomalin related soil protein (GRSP) production in proximate method. Nutrient accumulation, particularly total nitrogen (82.61 mg $plant^{-1}$), was also found to be higher in proximate method of inoculation. Our results demonstrate that the proximate method of inoculation may improve the early stage mycorrhizal symbiosis and inoculum performance in Saemangeum reclaimed soil.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.545-552
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• 2005

For the purpose of studying on the seepage characteristics of embedded gravel layer in embankment, laboratory model tests were carried out. The embedded layer under embankment was $19{\sim}26mm$ diameter of gravel and those embankment materials were Saemangum dredged sand, river sand and mixed(1:1) sand with dredged and river one. Those permeability coefficients of three different sands are $5.00{\times}10^{-5}$, $3.00{\times}10^{-4}$, $7.50{\times}10^{-5}m/s$, respectively. Seepage characteristics of these results are as follows; 1) The Reynolds number of water flow through embedded gravel layer in three different permeable soils is less then 10, it is laminar flow. 2) These flow velocities through embedded gravel layer in soils are in proportion to these hydraulic gradients, it is Darcy flow. 3) These Darcian permeability coefficients of water flow through embedded gravel layer in soils show as $2.95{\times}10^{-3}$, $1.38{\times}10^{-2}$, $3.33{\times}10^{-3}$m/s, respectively, by varying permeability of embankment soils and embankment lengths. It is approximately 100 times of those permeability coefficients of embankment materials.