• 지질공학
• /
• 제27권4호
• /
• pp.451-462
• /
• 2017

Physical weathering caused by external forces and chemical weathering caused by the decomposition or alteration of constituent materials are the two factors that dominate the mechanical properties of rocks. In this study, a field investigation was undertaken to identify the physical and chemical weathering characteristics of the biotite granite and granitic weathered soils in Gyeongju, South Korea. Samples were collected according to their grade of weathering and subjected to modal analysis, XRD analysis, XRF analysis, physical property tests, particle size distribution tests, and slake durability tests. Modal and XRD analysis identified these rocks as biotite granite; secondary alteration minerals were not observed. Physical property tests and particle size distribution analyses indicate an average porosity of 41.28% and a sand content of > 90 wt.%. These values are somewhat higher than those of granites in general. The results of the slake durability test and XRF analyses show that the physical and chemical weathering indices of the samples vary with the degree of weathering.

• Journal of Biosystems Engineering
• /
• 제33권6호
• /
• pp.430-437
• /
• 2008

Optical diffuse reflectance sensing in visible and near-infrared wavelength ranges is one approach to rapidly quantify soil properties for site-specific management. The objectives of this study were to investigate effects of preprocessing of reflectance data and determine the accuracy of the reflectance approach for estimating physical and chemical properties of selected Missouri and Illinois, USA surface soils encompassing a wide range of soil types and textures. Diffuse reflectance spectra of air-dried, sieved samples were obtained in the laboratory. Calibrations relating spectra to soil properties determined by standard methods were developed using partial least squares (PLS) regression. The best data preprocessing, consisting of absorbance transformation and mean centering, reduced estimation errors by up to 20% compared to raw reflectance data. Good estimates ($R^2=0.83$ to 0.92) were obtained using spectral data for soil texture fractions, organic matter, and CEC. Estimates of pH, P, and K were not good ($R^2$ < 0.7), and other approaches to estimating these soil chemical properties should be investigated. Overall, the ability of diffuse reflectance spectroscopy to accurately estimate multiple soil properties across a wide range of soils makes it a good candidate technology for providing at least a portion of the data needed in site-specific management of agriculture.

• Geomechanics and Engineering
• /
• 제22권3호
• /
• pp.227-236
• /
• 2020

Expansive soils are renowned for their swelling-shrinkage property and these volumetric changes resultantly cause huge damage to civil infrastructures. Likewise, subgrades consisting of expansive soils instigate serviceability failures in pavements across various regions of Pakistan and worldwide. This study presents the use of polypropylene fibers to improve the engineering properties of a local swelling soil. The moisture-density relationship, unconfined compressive strength (UCS) and elastic modulus (E₅₀), California bearing ratio (CBR) and one-dimensional consolidation behavior of the soil treated with 0, 0.2, 0.4, 0.6 and 0.8% fibers have been investigated in this study. It is found that the maximum dry density of reinforced soil slightly decreased by 2.8% due to replacement of heavier soil particles by light-weight fibers and the optimum moisture content remained almost unaffected due to non-absorbent nature of the fibers. A significant improvement has been observed in UCS (an increase of 279%), E₅₀ (an increase of 113.6%) and CBR value (an increase of 94.4% under unsoaked and an increase of 55.6% under soaked conditions) of the soil reinforced with 0.4% fibers, thereby providing a better quality subgrade for the construction of pavements on such soils. Free swell and swell pressure of the soil also significantly reduced (94.4% and 87.9%, respectively) with the addition of 0.8% fibers and eventually converting the medium swelling soil to a low swelling class. Similarly, the compression and rebound indices also reduced by 69.9% and 88%, respectively with fiber inclusion of 0.8%. From the experimental evaluations, it emerges that polypropylene fiber has great potential as a low cost and sustainable stabilizing material for widespread swelling soils.

• 지질공학
• /
• 제15권2호
• /
• pp.123-132
• /
• 2005

본 연구에서는 폐기물 매립장의 차수층으로 사용되는 벤토나이트 혼합토에 대한 연직침윤시험과 Frequency Domain Reflectometry 측정 장비를 이용한 유전율 측정시험을 수행하였다. 표준사, 화강풍화토, 벤토나이트 재료에 대해 다양한 배합 비율을 적용하여 제작된 벤토나이 트 혼합토의 체적함수비, 간극비, 유전율상수 등의 관계로부터 이들의 불포화 투수 특성을 파악하였다. 연구결과에 따르면 초기 벤토나이트 혼합비는 체적함수비 변화에 영향을 미치며, 체적함수비 변화는 간극비와 밀접한 관계를 가지고 있다. 또한 벤토나이트 혼합토의 체 적 함수비 변화는 유전율 반응으로부터 명확히 측정됨을 파악하였다. 벤토나이트 혼합토의 불포화 투수 특성을 파악하기 위한 본 연구에서 체적함수비와 유전율상수의 관계함수를 추정하였다.

• 한국토양비료학회지
• /
• 제42권3호
• /
• pp.201-206
• /
• 2009

신선유기물 (이탈리안 라이그라스), 신선유기물 + 부산물비료 그리고 부산물비료 처리 후 3년 동안 토양입단 발달상태를 조사한 결과, 토양별로는 모래 함량이 상대적으로 높은 새만금 간척지 토양 보다는 미사와 점토함량이 높은 고흥 간척지 토양에서의 입단형성이 더 양호한 것으로 나타났다. 유기물 자원 처리별로는 고흥 간척지 토양에서는 유의성 있는 차이가 나타나지 않았으나 (P<0.05), 새만금 간척지 토양에서는 녹비 형태의 신선 유기물 즉, 이탈리안 라이그라스를 처리한 시험구에서 가장 입단화도가 높게 나타났다. 유기물 종류별로는 이탈리안 라이그라스와 같은 신선 유기물을 단독 처리한 시험구에서 토양 입단의 중량평균직경이 가장 크게 나타났다. 간척지 토양의 물리성 및 토양구조 개선을 위한 유기물 처리시 신선유기물의 처리가 바람직하며, 불가피할 경우 일반 유기질/부산물비료의 단독처리보다는 신선유기물과 혼합하여 처리하는 것이 타당한 것으로 조사되었다.

• 복식문화연구
• /
• 제15권2호
• /
• pp.276-283
• /
• 2007

The purpose of this study were to investigate characteristic changes on nonwoven fabric for disposable work clothes by the yellow soil printing. It separate grind yellow soil as two different size of particles $45\sim52{\mu}m$ and $53\sim65{\mu}m$ for hand screen printing on three kind of nonwoven fabrics. To examine the effect of yellow soil printing on nonwoven fabric were to observe, dyeability by using spectrophotometer, moisture regain by oven method, air permeability, anion property and antibacterial activity. The results were as follows: When yellow soil concentration increased from 5 to 10%, K/S value also increased from 1.05 to 1.88. When yellow soil concentration increased, moisture regain also increased. In same concentration, moisture regain occurred higher as particle of small size. Air permeability decreased when the charcoal printing concentration increased. Anion occurrence appeared $140\sim160ion/cc$ from three different kinds of nonwoven fabrics in 3% and 9% yellow soil concentration. Therefore, occurred anion ineffectively. In concentration of 3%, rate of deodorization measured as 89%, 83% and 87%, and 9% concentration caused 96%, 86% and 93% of high deodorization. Antibacterial activity examination in nonfinished nonwoven fabric resulted range of 60%, however, 3% and 9% concentration finished nonwoven fabric resulted 99.9% of excellent antibacterial activity Surface temperature increased $1.5\sim2^{\circ}C$ by yellow soil finishing.

• Journal of Biosystems Engineering
• /
• 제32권6호
• /
• pp.448-454
• /
• 2007

This study was conducted to develop a 100 kPa soil tensiometer mainly consisted of a porous ceramic cup, water-holding tube, and a digital vacuum gauge, through theoretical design analysis and experimental performance evaluation. Major findings were as follows. 1. Theoretical analysis showed that air entry value of a porous media decreased as the maximum effective size of the pore increased, and the maximum diameter of the pores was $2.9\;{\mu}m$ for measuring up a 100 kPa of soil-water tension. 2. Property analysis of tensiometer porous cups supplied in Korean domestic market indicated that main components were $SiO_2$ and $Al_2O_3$ with a porosity range of $33.8{\sim}49.3%$. 3. The porous cup selected through sample fabrication and air-permeability tests showed weight ratios of 87% and 11% for $Al_2O_3$ and $SiO_2$. The analysis of SEM (scanning electron microscope) images showed that the sample was sintered at temperatures of about $1150^{\circ}C$, which consisted of pores with sizes of up to 25% of those for commercial porous cups. 4. The prototype soil tensiometer was fabricated using the developed porous cup and a digital vacuum gauge that could measure water tension with a pressure of 85 kPa in air tests. 5. In-soil tests of the prototype conducted during a period of 25-day drying showed that soil-water tension values measured with the prototype and commercial units were not significantly different, and soil-water characteristic curves could be established for different soils, confirming accuracy and stability of the prototype.

• 지질공학
• /
• 제18권3호
• /
• pp.311-319
• /
• 2008

주파수 인피던스를 이용하는 ThetaProbe ML2x인 ADR 형식의 토양함수비센서를 적용하여 주문진 표준사, 상주 화강 풍화토, 장수 편마암풍화토을 대상으로 실험을 수행하였다. 시험의 목적은 측정센서의 측정 정밀도를 측정로드부 삽입 깊이에 따른 변화 양상을 파악하였다. 흙매질은 체적함수비 함량과의 관계를 비교하기 위하여 건조상태와 습윤상태로 구분하여 수행하였다. 측정결과에서 측정로드부가 흙매질 내 5cm 이상 삽입되면 측정전압의 변화폭이 크게 감소하는 것을 파악하였다. 또한, 표준사와 같이 균질한 입자를 가진 흙보다는 점토와 실트 등과 같은 세립질을 함유한 화강풍화토와 편마암풍화토에서 측정전압이 안정적인 형태를 갖는 것으로 나타났다. 따라서, 측정치는 측정로드부가 다공질매질과의 접촉 면적이 커질수록 안정적인 값을 제공한다.

• 상하수도학회지
• /
• 제25권1호
• /
• pp.1-5
• /
• 2011

Arsenic is one of the most abundant contaminant found in waste mine tailings and soil around refinery, Because of its carcinogenic property, the countries like United States of America and Europe have made stringent regulations which govern the concentration of arsenic in soil. The study focuses on solidification/stabilization for removal of arsenic from soil. Cement was used to solidify/stabilize the abandoned soil primarily contaminated with arsenic (up to 68.92 mg/kg) in and around refinery. Solidified/stabilized (s/s) forms in the range of cement contents 5-30 wt % were evaluated to determine the optimal binder content. Revised Korean standard leaching tests (KSLT), toxicity characteristic leaching procedures (TCLP), Old Korea standard leaching test and revised Korea standard leaching test were used for chemical characterization of the S/S forms. The addition of 10 % cement remarkably reduced the leachability of arsenic in contaminated soil. The concentration of As in leachate of TCLP, KSLT, and old KSLT for soil are below the standard. However that in leachate of revised KSLT is above the standard. Because of extraction fluid used in revised KSLT is very strong acid. It is arsenic in s/s with binder should be exhaustingly leached. Therefore S/S process would not be available for As treatment in soil in Korea.

• 한국약용작물학회지
• /
• 제15권1호
• /
• pp.12-16
• /
• 2007

강활 주재배지인 봉화지역 밭토양의 토양 특성을 조사하고 강활재배지 토양의 특성을 분석하여 토양환경과 적정 이화학성을 구명하기 위하여 강활의 생육상황과 수량을 조사한 결과는 다음과 같다. 1. 봉화지역 밭토양의 토성은 사양토와 양토가 대부분이었고 경사는 $7\sim15%$가 가장 많았으며 다음이 $15\sim30%$이었다. 2. 토양 배수등급별 토성 분포에 있어서는 사양토와 양토는 배수 양호가 많았으나 양토는 불량등급도 있었다. 양질조사토나 양질사토는 매우 양호 등급이었다. 3. 강활 수량은 양토와 배수등급 약간양호에서 289kg/10a으로 가장 많았는데 식양토와 배수불량등급에서 수량이 가장 적었다. 4. 강활 재배지의 토양유기물, 칼리함량, EC는 배수등급이 불량할수록 적어졌으며 그 외 함량은 배수등급간에 일정한 경향이 없었다.