• Agricultural and Biosystems Engineering
• /
• v.7 no.1
• /
• pp.18-26
• /
• 2006

In-field site-specific nitrogen (N) management increases crop yield, reduces N application to minimize the risk of nitrate contamination of ground water, and thus reduces farming cost. Real-time N sensing and fertilization is required for efficient N management. An 'on-the-go' site-specific N management system was developed and evaluated for the supplemental N application to com (Zea mays L.). This real-time N sensing and fertilization system monitored and assessed N fertilization needs using a vision-based spectral sensor and controlled the appropriate variable N rate according to N deficiency level estimated from spectral signature of crop canopies. Sensor inputs included ambient illumination, camera parameters, and image histogram of three spectral regions (red, green, and near-infrared). The real-time sensor-based supplemental N treatment improved crop N status and increased yield over most plots. The largest yield increase was achieved in plots with low initial N treatment combined with supplemental variable-rate application. Yield data for plots where N was applied the latest in the season resulted in a reduced impact on supplemental N. For plots with no supplemental N application, yield increased gradually with initial N treatment, but any N application more than 101 kg/ha had minimal impact on yield.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.40 no.2
• /
• pp.112-122
• /
• 1998

Measurement of electrical resistivity in soils has been used for many years with purpose of estimating in situ porosity or density. Recently electrical resistivity has also been used as an indicator of soil contaimination. This paper presents the result of laboratory experiment to investigate the resistivity variation in contaminated sandy soils. The results can be used with the Cone Penetrometer Test (CPT) result to analyse ground condition. In the experiment, the water content and leachate concentration of soils were controlled by groundwater and leachate, and then the resistivity measurement was made with 'STING-R1' by Advanced Geosciences Inc. In the case of using groundwater, the resistivity was in the range of over 1000${\omega}{\cdot}m$, but in the case of using polluted water by leachate, the resistivity decreased significantly down to 10~ 100${\omega}{\cdot}m$ for the same moisture content. Also the resistivity varied according to the degree of saturatrion. Therefore, if soil is contaminated by leachate, the CPT with electrical resistivity sensor might be used to investigate the contamination status and plume migration. But exact component of leachate and the pollutant concentration are still hard to identify.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.03a
• /
• pp.905-913
• /
• 2008

The water resource depending on mostly surface water has many problems, such as contaminated and unpredicted contamination event. For this reason, it has been employed highly technical treatment method for them, such as ground water dam and river bank filtration. it has been developed the radial collector wells in kind of bank filtration to increase efficiency for in-taking the water resource insead of the vertical well needed many wells to take more resource. But it has many problems with the incumbent method to bore the horizontal hole for radial collector wells, such as filling with the filter material outside of a strainer by watering, jamming as retrieving the casing tube with the filter material, eccentric boring etc. To reduce the problems of incumbent equipment, it has been developed the horizontal boring equipment and performed the field trial tests several times, which have bits and water jetting system with rotating the cone-shaped front to be excavated easily. In this paper, it was compared the brand-new with the incumbent non-rotating pressing insertion method. Also it was shown the problems of the incumbent method was reduced effectively.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2005.03a
• /
• pp.491-498
• /
• 2005

Acid Rock Drainage(ARD) is the product formed by the atmospheric(i.e. by water, oxygen and carbon dioxide) oxidation of the relatively common iron-sulphur minerals pyrite($FeS_2$). ARD causes the acidification and heavy metal contamination of water and soil and the reduction of slope stability. In this study the generation characteristics and the prediction of ARD of various road cut slopes were studied. An attempt to classify the rocks into several groups according to their acid generation potentials was made. Acid Base Accounting(ABA) tests, commonly used as a screening tool in ARD predictions, were performed. Sixteen rock samples were classified into PAF(potentially acid forming) group and four rock samples into NAF(non-acid forming) group. The chemical analysis of water samples strongly suggested that ARD with high content of heavy metals and low pH could pollute the ground water and/or stream water.

• Current Optics and Photonics
• /
• v.1 no.3
• /
• pp.247-251
• /
• 2017

In this study, an ultraviolet Raman spectrometer was designed and fabricated to detect chemical contamination on the ground. The region of the Raman spectrum that indicated the characteristics of the chemicals was $350-3800cm^{-1}$. To fabricate a Raman spectrometer operating in this range, the layout and angle of optical components of the spectrometer were designed using a grating equation. Experimental devices were configured to measure the Raman spectra of chemicals based on the fabricated Raman spectrometer. The wavenumber of the spectrometer was calibrated by measuring the Raman spectrum of polytetrafluoroethylene, $O_2$, and $N_2$. The spectral range of the spectrometer was measured to be 23.46 nm ($3442cm^{-1}$) with a resolution of 0.195 nm ($30.3cm^{-1}$) at 253.65 nm. After calibration, the main Raman peaks of cyclohexane, methanol, and acetonitrile were found to be similar to the references within a relative error of 0.55%.

• Journal of Korean Society on Water Environment
• /
• v.24 no.5
• /
• pp.523-532
• /
• 2008

A phase II site investigation and feasibility study was conducted at a military mortar shooting range near the demilitarized zone (Kyunggi, South Korea) to assess the extent of contaminants migration to the nearby Imjin river in which a flood control dam is under construction. The results showed that silty-clay soils around target areas were co-contaminated with heavy metals (Cd, Cu, and Pb) and explosives (HMX, RDX, and TNT). The total amount of contaminant was estimated to be 497.1 kg-RDX, 20.6 kg-HMX, 1.4 kg-TNT, 35.2 kg-Cd, 4,331 kg-Cu, and 5,115 kg-Pb, respectively. Both heavy metals and explosives were almost equally distributed on each soil particle size fraction. Neither subsurface soil samples nor ground water samples showed signs of contamination above the environmental criteria. The major migration route of contaminants was soil particles in surface run-off during rain at which a mass discharge rate of 30.0 mg-RDX/hour was observed.

• Current Industrial and Technological Trends in Aerospace
• /
• v.9 no.1
• /
• pp.158-164
• /
• 2011

Check valves developed for aerospace applications and commercially available for the applications are investigated. The examples include the ones for launch vehicles, SSME (Space Shuttle Main Engine) and GSE (Ground Support Equipment) purges developed by NASA, requiring high reliability, and the ones by KARI. Also the commercial ones for room and cryogenic temperatures by major valve US companies. Relations of design factors such as seal materials and spring rate to principal performances like operating temperature/pressure and cracking pressure are explained. Then potential operational problems such as chatter and contaminations are explained. Also, filters, fittings for end connections and cleanliness requirements for the applications are considered.

• Journal of Environmental Science International
• /
• v.11 no.3
• /
• pp.227-234
• /
• 2002

Laboratory experiments were conducted to examine the behavior of metalaxyl in environment which was used as pesticide in green soil of golf course and as functions of the characteristics of adsorption, desorption and degradation in soil texture and organic matter contents. Acid water containing metalaxyl was conducted to evaluate the effects on adsorption, desorption and degradation. The adsorption of metalaxyl played more significant role in organic contents than clay contents, and pH Increases more pH 2.5 than pH 5.6. The desorption of metalaxyl from contaminants soil decreased higher organic contents LS-soil than S-soil, but the desorption amount of metalaxyl increased more pH 5.6 than pH 2.5. The rate of degradation of metalaxyl in green soil environmental increased higher organic contents LS-soil than S-soil and decreased more pH 2.5 than pH 5.6. These results indicated that the behavior of metalaxyl of the green soil was affected the soil texture of the golf course. Increasing of organic contents, the adsorption amount of metalaxyl on soil increased. Moreover the decrease of the pH of solution increased adsorption amounts and decreased desorption amounts. As the results, the transportation of metalaxyl in soil decreased the acidic rates. The acidification of soil by the acid rain increased the adsorption amount of metalaxyl, but the degradation of metalaxyl decreased. Therefore, it is possible to sustain contamination in run-off the stream and ground water by residuals in soil.

• Environmental Engineering Research
• /
• v.13 no.3
• /
• pp.107-111
• /
• 2008

Water quality contamination issues are of critical concern to human health, whilst pesticide release generated from irrigated land should be considered for protecting natural habitats and human health. This paper suggests new method for evaluation and analysis using the GIS technique based on integrated spatial modeling framework. The pesticide use on irrigated land is a subset of the larger spectrum of industrial chemicals used in modern society. The behavior of a pesticide is affected by the natural affinity of the chemical for one of four environmental compartments; solid matter, liquid, gaseous form, and biota. However, the major movements are a physical transport over the ground surface by rainfall-runoff and irrigation-runoff. The irrigated water carries out with the transporting sediments and makes contaminated water by pesticide. This paper focuses on risk impact identification and assessment using GIS technique. Also, generated data on pesticide residues on farmland and surface water through GIS simulation will be reflected to environmental research programs. Finally, this study indicates that GIS application is a beneficial tool for spatial pesticide impact analysis as well as environmental risk assessment.

• Journal of agriculture & life science
• /
• v.44 no.3
• /
• pp.7-14
• /
• 2010

Alternative subirrigation way, capillary wick system (CWS) was tested to reduce labor cost, waste water, contamination of ground water, and use of fungicide compared to overhead irrigation system (OIS). CWS helped reduce remarkably the working hours for watering from 4 hours in OSI to just 5 minutes. Labor cost was saved 98% in CWS compared to OIS. By the physical characteristics of various growing media, 1 coconut coir+2 perlite (v/v) mixture was selected because it had an ideal distribution of three phase, e.g. 1 solid: 1 liquid: 2 gas phase. Medium mixture containing scoria had so high bulk and particle density to hurt root. In bark-containing medium, the liquid phase and the percent saturation of liquid phase with time elapsed was lower than that of other mixture. It meant that the mixture contained very low level of water. Application of CWS for cyclamen pot production played an important role in reducing the incident of fusarium wilt symptom from 18% in conventional over watering system to 4%. Cyclamen pot irrigated by capillary wick had shorter petiole and more leaves than those by overhead watering. As a result, this system was highly beneficial to get uniform pot products with high quality. It improved water and nutrient solution efficiency relative to conventional overhead irrigation system (OIS).