• Journal of the Korean Society of Clothing and Textiles
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• v.10 no.3
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• pp.27-36
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• 1986

The purpose of this study was, to estimate the detergency of commercial detergent and to examine the interrelationship between detergency and detergent characteristics, detergent concentration, fiber characteristics, and Rolling-up phenomenon which is the major removal mechanism of oily soil. A mixture of oleic acid-olive oil was used as oily soil. The detergency was estimated by analysis of oleic acid on cotton ana polyester fabrics before and after washing by means of liquid scintillation counting. The Rolling-up of oily soil from PET film was observed and change of contact angle and removal time were measured. The results were as follows ; 1. In the case of soaps and powder synthetic detergents, the optimum concentrations we-re about $0.2\~0.3\%$. And detergencies of liquid synthetic detergents were considerably low, and the detergency was continually increased up with increasing concentration to $0.5\%$, which seemed to be caused by the lower pH than that of soap and powder synthetic deter-gent solutions. 2. As the effect of external or internal fiber structure; the detergency of cotton was lower than that of polyester. 3. In the observation of Rolling-up, the contact angle increased and the Rolling-up time became shorter with increasing detergent concentrations ($0.05\~0.5\%$). And it was confirmed that detergency was increased with Rolling-up effect. In addition, the study on the actual laundry condition was studied using the questionaire. From the results, about $76\%$ of households used the concentration of detergent roughly or excessively and housewives were highly concerned on the recommended dose, but grade of practice were very low.

• Korean Journal of Remote Sensing
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• v.27 no.6
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• pp.761-771
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• 2011

The sensitivity of microwave scattering to the dielectric properties and the geometric structure of soil surfaces makes radar remote sensing a challenge for a wide range of environmental issues directly related to the condition of natural surfaces. Especially, the potential for retrieving soil moisture with a high spatial and/or temporal resolution represents a significant contribution to hydrological and ecological modeling. This paper aims to review the current state of the art in SAR technology and methodological issues towards the discovery of a new potential accurate monitoring of soil moisture changes. In this paper, important parameters or constraints significantly affect the sensitivity of the measurements to soil moisture, such as roughness statistics, spatial resolution, and local topography, are discussed to improve the applicability of SAR remote sensing techniques. This study particularly intends to discuss important notes for developing smart and reliable methods capable of retrieving geophysical information.

• Geomechanics and Engineering
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• v.20 no.6
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• pp.505-516
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• 2020

In recent years, Nano-technology significantly invaded the field of Geotechnical engineering, particularly in soil stabilisation techniques. Stabilisation of weak soil is envisioned to modify various soil characteristics by the addition of natural or synthetic materials into the virgin soil. In the present study, laboratory experiments were executed to investigate the influence of nano-silica particles in the consistency limits, compressive strength of the soft clay blended with cement. The results revealed that the high compressibility behaviour of soft clay modified to medium-stiff condition with fewer dosages of cement and nano-silica. The mechanism behind the strength development is verified with the previous researches as well as from Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction test (XRD) and Scanning Electron Microscopy (SEM) analysis. Based on the results, the presence of nano-silica in soft clay blended with cement has a positive effect on the behaviour of soil. This technique proves to be very economical and less detrimental to the environment.

• Korean Journal of Remote Sensing
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• v.33 no.6_1
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• pp.947-960
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• 2017

Soil moisture plays an important role to affect the Earth's radiative energy balance and water cycle. In general, satellite observations are useful for estimating the soil moisture content. Passive microwave satellites have an advantage of direct sensitivity on surface soil moisture. However, their coarse spatial resolutions (10-36 km) are not suitable for regional-scale hydrological applications. Meanwhile, in-situ ground observations of point-based soil moisture content have the disadvantage of spatially discontinuous information. This paper presents an experimental soil moisture retrieval using Sentinel-1 SAR (Synthetic Aperture Radar) with 10m spatial resolution for cropland in South Korea. We developed a soil moisture retrieval algorithm based on the technique of linear regression and SVR (support vector regression) using the ground observations at five in-situ sites and Sentinel-1 SAR data from April to October in 2015-2017 period. Our results showed the polarization dependency on the different soil sensitivities at backscattered signals, but no polarization dependence on the accuracies. No particular seasonal characteristics of the soil moisture retrieval imply that soil moisture is generally more affected by hydro-meteorology and land surface characteristics than by phenological factors. At the narrower range of incidence angles, the relationship between the backscattered signal and soil moisture content was more distinct because the decreasing surface interference increased the retrieval accuracies under the condition of evenly distributed soil moisture (during the raining period or on the paddy field). We had an overall error estimate of RMSE (root mean square error) of approximately 6.5%. Our soil moisture retrieval algorithm will be improved if the effects of surface roughness, geomorphology, and soil properties would be considered in the future works.

• Journal of Environmental Health Sciences
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• v.31 no.4 s.85
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• pp.280-286
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• 2005

The purpose of this investigation was to evaluate removal efficiency of $NH_4-N$ using the soil column. Soil, oyster shell and natural zeolite were used as a supporting media of soil column. Removal efficiencies of $NH_4-N$ were $35.9\%,\;41\%\;and\;93.4\%$ for the soil column packed with soil, natural $zeolite(20\%)$ and oyster $shell(20\%)$ at HRT of 72 hours, respectively. The addition of $20\%$ oyster shell to the soil accelerated nitrification in soil column. The influent ammonia nitrogen was mostly converted to nitrate nitrogen in the soil column and little ammonia nitrogen was found in the effluent. When the influent $NH_4-N$ concentration was 200 mg/l, the NIL-N removal was decreased at HRT of 48 hours, while nitrification was significantly increased after mechanical aeration. It was suggested that nitrification from higher $NH_4-N$ concentration was more affected by aeration in soil column process. The number of nitrifiers was approximately in a level of about $10^6\;MPN/g{\cdot}soil$ in the soil column mixed with oyster shell ($20\%$).

• Korean Journal of Remote Sensing
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• v.39 no.6_1
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• pp.1185-1193
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• 2023

The increasing interest in soil moisture data from satellite imagery for applications in hydrology, meteorology, and agriculture has led to the development of methods to produce variable-resolution soil moisture maps. Research on accurate soil moisture estimation using satellite imagery is essential for remote sensing applications. The purpose of this study is to generate a soil moisture estimation map for a test area using KOMPSAT-3/3A and KOMPSAT-5 SAR imagery and to quantitatively compare the results with soil moisture data from the Soil Moisture Active Passive (SMAP) mission provided by NASA, with a focus on accuracy validation. In addition, the Korean Environmental Geographic Information Service (EGIS) land cover map was used to determine soil moisture, especially in agricultural and forested regions. The selected test area for this study is the western part of Jeju, South Korea, where input data were available for the soil moisture estimation algorithm based on the Water Cloud Model (WCM). Synthetic Aperture Radar (SAR) imagery from KOMPSAT-5 HV and Sentinel-1 VV were used for soil moisture estimation, while vegetation indices were calculated from the surface reflectance of KOMPSAT-3 imagery. Comparison of the derived soil moisture results with SMAP (L-3) and SMAP (L-4) data by differencing showed a mean difference of 4.13±3.60 p% and 14.24±2.10 p%, respectively, indicating a level of agreement. This research suggests the potential for producing highly accurate and precise soil moisture maps using future South Korean satellite imagery and publicly available data sources, as demonstrated in this study.

• Journal of Korea Water Resources Association
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• v.56 no.3
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• pp.211-224
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• 2023

In this study, a soil moisture estimation was performed using the Water Cloud Model (WCM), a backscatter model that considers vegetation based on SAR (Synthetic Aperture Radar). Sentinel-1 SAR and Sentinel-2 MSI (Multi-Spectral Instrument) images of a 40 × 50 km² area including the Yongdam Dam watershed of the Geum River were collected for this study. As vegetation descriptor of WCM, Sentinel-1 based vegetation index RVI (Radar Vegetation Index), depolarization ratio (DR), and Sentinel-2 based NDVI (Normalized Difference Vegetation Index) were used, respectively. Forward modeling of WCM was performed by 3 groups, which were divided by the characteristics between backscattering coefficient and soil moisture. The clearer the linear relationship between soil moisture and the backscattering coefficient, the higher the simulation performance. To estimate the soil moisture, the simulated backscattering coefficient was inverted. The simulation performance was proportional to the forward modeling result. The WCM simulation error showed an increasing pattern from about -12dB based on the observed backscattering coefficient.

• Korean Journal of Environmental Agriculture
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• v.11 no.2
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• pp.116-124
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• 1992

This study was conducted to elucidate degradation pattern of two synthetic pyrethroid insecticides, bifenthrin having 2-methylbiphenyl group and cyhalothrin having ${\alpha}$-cyano benzyl ester group in theirs alcohol moiety, in two soils and aqueous media under laboratory conditions. The half-life of bifenthrin was 85.1 days and 12,4 days in Chilgok and Bokhyen soil of aerobic upland condition, respectively, and that of cyhalothrin was 54.6 days and 32.2 days. Bifenthrin and cyhalothrin were degraded very slowly under anaerobic flooded condition and sterilized. Their degradation seemed to be mainly mediated by aerobic microorganisms in soil. Bifenthrin and cyhalothrin were degraded more rapidly in Bokhyen soil with rich organic matter than Chilgok soil. Cyhalothrin was degraded 30 days faster than bifenthrin under aerobic upland condition of two soils. Cyhalothrin was degraded more than bifenthrin in alkaline solution of pH 10, but cyhalothrin and bifenthrin were degraded very slowly in acidic solution of pH 2 and 6.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.4
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• pp.453-457
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• 2010

To investigate the difference in N isotope ratio ($^{15}N/^{14}N$, expressed as ${\delta}^{15}N$) among N sources (synthetic fertilizer, livestock manure, and manure compost), eight synthetic fertilizer, four livestock manure, and thirty-seven compost samples were collected and analyzed for ${\delta}^{15}N$. The mean ${\delta}^{15}N$ values of N sources were $-1.5{\pm}0.5$‰ (range: -3.9 to +0.5‰) for synthetic fertilizer, $+6.3{\pm}0.4$‰ (+5.3 to +7.2‰) for manure, and $+16.0{\pm}0.4$‰ (+9.3 to +20.9‰) for compost. The lower ${\delta}^{15}N$ of synthetic fertilizer was attributed to its N source, atmospheric $N_2$ of which ${\delta}^{15}N$ is 0‰ Meanwhile, more $^{15}N$-enrichment of compost than manure was assumed to be resulted from N isotopic fractionation (faster loss of $^{14}N$-bearing compound than $^{15}N$) associated with N loss particularly via $NH_3$ volatilization during composting. Therefore, our study shows that ${\delta}^{15}N$ values could successfully serve in discriminating two major N sources (synthetic fertilizer and compost) in agricultural system.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.2
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• pp.35-43
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• 2011

This study aimed to investigate the engineering characteristics of PVA fiber-cement-soil mixture used to prevent or reduce brittle failure of cement-soil mixtures due to the tensile strength increase from the addition of a synthetic fiber. The engineering characteristics of PVA fiber-cement-soil mixtures composed of PVA fiber, soil, and a small amount of cement was analysed on the basis of the compaction test, the unconfined compression test, the tensile strength test, the freezing and thawing test, and the wetting and drying test. The specimens were manufactured with soil, cement and PVA fiber. The cement contents was 2, 4, 6, 8, and 10%, and the fiber contents was 0.4, 0.6, 0.8, and 1.0% by the weight of total dry soil. To investigate the strength characteristics depending on age, each specimen was manufactured after curing at constant temperature and humidity room for 3, 7 and 28 days, after which the engineering characteristics of PVA fiber-cement-soil mixtures were investigated using the unconfined compression test, the tensile strength test, the freezing and thawing test, and the wetting and drying test. The basic data were presented for the application of PVA fiber-cement-soil mixtures as construction materials.