• Journal of the Korean Geotechnical Society
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• v.39 no.2
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• pp.31-42
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• 2023

A study was conducted to use soil color obtained from digital im ages as an indicator of soil water content. Digital images of Jumoonjin standard sand with five different water contents were captured under nine different lighting conditions. Through digital image processing, the soil color of the sample was obtained based on the CIELAB color system, and the effect of lighting conditions and water content on the soil color was analyzed. The results indicated that L^* showed a high correlation with illuminance, whereas a^* and b^* showed a high correlation with color temperature. As the water content increased, L^*, which represents the brightness of the soil color, decreased, and a^* and b^* increased. Therefore, the soil color changed from green and blue to red and yellow. Based on the regression analysis results of lighting conditions, water content, and soil color, a water content predicting method based on the soil color of silica-based sand photographed under irregular light conditions was proposed. The proposed method can predict the water content with a m axim um error of 0.29%.

• Journal of the Korean Geotechnical Society
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• v.38 no.5
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• pp.61-71
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• 2022

Soil color is used to determine soil classification and its physical, chemical, and biological properties. Visual determination is the most commonly used method for identifying soil color. However, it is subjective and, in many cases, non-repeatable. Digital image processing obtains useful information from digital images, accelerates soil classification, and enables the rapid identification of soil types in a field. This study develops a digital image processing-based soil color analysis technology that can consider irregular light conditions in the field. The digital image studio was designed to simulate the characteristics of natural light (illuminance and color temperature). Also, digital images of two soil samples (Jumoonjin sand and Anseong weathered soil) were captured under 12 different light conditions. For the RGB and CIELAB color systems, soil color intensities of 24 images were obtained using digital image processing. CIELAB was suitable for dealing with irregular light conditions in the field.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.6
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• pp.329-333
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• 2006

Most of volcanic ash soils in South Korea are distributed in Jeju province which is an island placed on southern part of Korea and has steep slope mountain area. There are many soils containing high contents of organic matter (OM) derived from volcanic ash in Jejudo, also. Therefore, irrigation and drainage in volcanic ash soil different with general soil which has low OM content have to be applied with another management way, but studies searching appropriate methods for them are set on insufficient situation because the area of volcanic ash soil in South Korea is only 1.3% (130,000ha). This study was conducted for analysis of soil water content and irrigation quantity appropriate for crops cultivated in volcanic ash soil with high OM content. Although soils with different soil color have the same soil texture, soil water characteristics curve by soil color showed the difference of water retention capability by OM content. But, this characteristics classified with soil color could be unified by scaling technique with similitude analysis method which get dimensionless water content using a present water content, a residual water content and saturated water content (or water content at 10kPa). A relation of gravimetric soil water content (GSWC) and dimensionless water content by the results showed a form of power function. The dimensionless water content (DWC) express a relative saturation degree of present water content. This was also expressed by van Genuchten model which describe the relation between relative saturation degrees and matric potentials. These results on soil water characteristics curve (SWCC) of volcanic ash soil will be the basic of irrigation plan in area having high organic contents into soil.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.3
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• pp.221-228
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• 2007

Quantitative analysis of distribution characteristics of soils in Jeju Island was conducted by using geographic information system (GIS) technology. Soil series could be classified 5 groups after cluster analysis with proximity ratios among soil series which mean ratios of boundary lengths of other soils to total boundary length. Classification with proximity only was similar to conventional classification system at detailed soil map although conventional system was made from several criteria such as soil color, altitude and chemical characteristics of soils. Altitudinal sequence of soil series was also suggested from representative altitudes of them which could be found from areal distribution curve along altitudes. The sequence was brown forest soils - black soils - very dark brown soils - dark brown soils from the peak of Halla Mt. to the coast on all sides, which maybe related to pedogenesis process in Jeju Island.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.3
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• pp.213-219
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• 1992

Geomorphological properties for the phylite-derived soil were examined to relate processes to four landscape positions, shoulder, backslope, footslope, and toeslope in Chungbuk. The distribution of Ogcheon-geology system was 216 thousand ha in South Korea. 2 orders, 3 suborders, 4 great groups, 5 subgroups, and 9 series were mapped. Soil color was interlocked by landscape. Soil color index values and $Fe_2O_3$ contents increased with soil-drainge class. Silt/clay and Ca/Mg ratios tended to narrow wish elevation and decreased with depth. Therefore, profile development or age on the landscape position was shoulder>backslope>footslope>toeslope. Color index(C2m) has a sighificant correlation with $Fe_2O_3$, in soil profile($r=0.777^{**}$). Pedologic type was continuity/discontinuity and soil property changes of depth<12cm would have a continous function.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.2
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• pp.141-146
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• 1984

Variation of soil characteristics and purity were examined within mapping unit and estimates were given for the number of samples required to reach predetermined levels of accuracy for black soil, VDBr. soil, DBr. soil, and brown soil in Jeju. Variation of chemical properties except pH and CEC was higher than that of physical properties. Brown soil showed the lowest variation and hence required the smallest sample size. The soils examined were correctly classified with regard to brown soil at purity 74.1, to DBr. soil 60.8, to black soil 55.6, and to VDBr. soil 46.9%. Sample calculation was presented which showed approximate sample sizes required to detect the difference of 10 and 20% of the mean with 0.95 confidence level.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.153-155
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• 2001

법송 방조제 조성지역 매립부 지반의 측방 및 수직변화를 조사하였다. 매립부 지반은 측방 및 수직으로 구성광물과 풍화정도에서 차이를 보여준다 이러한 차이는 기원암의 차이를 반영하는 것으로 편광현미경분석, 주사전자현미경분석, X-선회절분석에서 공통적으로 인지 할 수 있다. 해성점토층의 출현심도는 10m의 일정한 심도로 분포하여 방조제 축조이전 해성층이 수평층이었음을 지시하며 이러한 심도는 매립층의 하한선이 된다. 매립물질의 토색,토성. 풍화도, 구성광물차이에 의한 매립부 지반은 모두 같은 모재를 사용하여 매립되지 않았음을 지시하며 매립물질이 층서구조를 가지고 있는 점은 방조제의 수 차례에 걸쳐 조성되었음을 지시한다. 조사 결과 방조제 코어부와 성토부는 서로 다른 시기에 매립되었을 것으로 추정되며 성토부의 조성은 서로 다른 기원지의 모재를 사용하여 3회 이상에 걸쳐 시행되었음을 의미한다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.134-139
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• 2002

살내 유적지의 발굴조사에서 지질물리학에 기초한 연구방법과 적용성을 검토하고자 발굴과 아울러 지구물리탐사를 실시하였다. 심도에 따라 구분한 전기비저항에서 토양 구성물질의 차이에 의한 전기비저항의 변화와 퇴적물의 공급방향을 유추할 수 있다. 지하레이더탐사의 반사단면에서 퇴적층의 분급과 입도에 따라 구분되는 층리의 경계를 규명할 수 있는데, 실트의 구성비가 높은 지층들의 반사면은 측방 연장성이 좋은 반면 자갈의 구성비가 높은 지층의 반사면들은 불규칙한 기복을 보여준다. 지층 반사면의 형태로부터 고환경의 정보를 획득할 수 있는데, 살래유적지의 경우 문화층은 세립의 실트와 모래와 우세한 지층에 해당하며 층서에서 자갈층의 반복과 지층 경사는 퇴적물의 공급에 관련되는 고수계의 위치와 하천의 지속적으로 범람하는 환경을 지시한다. 주거 유적지의 대자율탐사에서 유적지 경계부의 토양은 주변에 비해 낮은 대자율을 가진다. 대자율 이상대를 형성하는 토양은 주거지 내부에 한정되며 이들은 황색계열의 토색으로 소성에 의한 것으로 추정된다.

• Journal of Environmental Impact Assessment
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• v.32 no.3
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• pp.166-175
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• 2023

This study aims to identify the cause of the red-water occurrence (the phenomenon of water being red) that occurs at some points and sections of rivers in Yongin City. As a result of conducting a preliminary investigation, total three sites were selected as the investigation point as it was found that the red-water occurrence continued. As a result of the investigation, it is judged that the cause of the red-water in Yongin-city river is due to the soil color and iron content of the region. JPS, SBS, and JJS sites all showed that the color of soil is mainly consist of reddish brown and red-yellow. The average Fe concentration was 13.75 mg/L, 10.85 mg/L, and 1.31 mg/L, for each sites, and considering that the Fe concentration in general river water was less than 0.5 mg/L, it was confirmed that the concentration was quite high. At the JPS and JJS points, the red-water occurrence occurred mainly in stagnant places, which is believed to be strengthened by the reaction of organic and microorganisms. In the case of SBS, the wateris red, but as a result of observing the actual color, it is judged that the iron component deposited in the pipe causes an optical illusion with a deep red color. In addition, it is believed that the iron concentration can be reduced to the general river water concentration range by removing the particulate iron component through a decrease of more than 95% as a result of filtering with glass fiber filter with particulate iron. As a result of this study, it is necessary to manage the river to maintain the flow, and it is believed that the occurrence of red-water at the survey point can be alleviated through uptake action through planting and agglomeration precipitation and agglomeration filtration methods for particulate iron treatment.

• Journal of the Korean Geographical Society
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• v.44 no.4
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• pp.463-480
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• 2009

The weathering properties and provenance of loess-paleosol sequence deposited on gravel layer of river terrace in Bongdong-eup, Wangju-gun, Jeonbuk Province are examined using soil analysis, magnetic susceptibility measurement, grain size and element analysis. The Bongdong section consists of, from top to bottom, Layer 1(paleosol), Layer 2(loess), Layer 3(paleosol) and the gravel layer of river terrace. The magnetic susceptibility values show the systematic variations in the sequence and the results of grain size analysis reveal that the sequence was deposited by not fluvial or slope process, but eolian process, and that contains finer materials than the Daecheon loess and Chinese Loess Plateau. Among the results of soil analysis, organic contents indicate systematic variations similar to the magnetic susceptibility. The wet soil colors further reflect the characteristics of the sequence rather than the dry soil colors. Based on the analytical results of major and rare earth elements, the eolian materials contained in the sequence were deposited by the materials originated from the areas where the Chinese Loess Plateau has been originated or the reworked materials from the Chinese Loess Plateau, and after the depositions, the materials experienced the intensive chemical weathering under the humid-warm climatic conditions in the Korean Peninsula.