• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 가을 학술발표회 논문집
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• pp.245-252
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• 2002

The roughness of Joomoonjin sand and the Dongchun river sand was analysed by the fractal theory. It was found that the fractal dimension(D$\_$F/) of Joomoonjin sand is a little smaller than the Dongchun river sand. That means Joomoonjin sand is smoother than the Dongchun river sand. The measurements of D$\_$F/ of different fraction of the Donchun river sand showed that large particles were rougher than fine particles. The shapes of both sands were analysed by the Discrete Fourier Transform(DFT) and the Grid-based(GB) method. Normalization of coefficients with respect to size, starting point and its orientation made the coefficients invaried to these characteristics. The mean of the normalized coefficients was used to reconstruct the average shape for both sands, respectively. The measurements of the ellipticity ratio of different fraction of both sands showed that Joomoonjin sand is slightly flatter than the Dongcun river sand.

• 한국지반공학회논문집
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• 제15권3호
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• pp.113-129
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• 1999

본 연구에서는 사질토 지반에서의 굴착단계별 연성 벽체의 거동분석을 수행하기 위해 흙막이벽의 모형실험을 실시하였다. 모형 흙막이벽 실험에서는 재료의 역학적 특성이 비교적 널리 알려진 주문진 표준사를 이용하여 상대밀도가 79%, 41%, 24%인 모형지반을 조성한 후 모형벽체의 연성지수를 변화시켜 각 굴착단계별로 배면지반과 연성 벽체의 거동특성을 규명하였다. 본 연구에서는 벽체의 수평변위, 벽체의 배면에 작용하는 수평토압, 굴착으로 인한 배면지반의 침하량 및 침하영향거리, 벽체에 작용하는 앵커의 하중, 그리고 벽체에 작용하는 휨모멘트와 축력에 대해 굴착단계에 따라 살펴보고 이를 토대로 지반과 벽체의 거동특성을 분석하였다.

• 대한토목학회논문집
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• 제13권5호
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• pp.261-273
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• 1993

불포화 영역에서의 침투현상이나 역학적 특성을 파악하기 위해서는 불포화투수계수와 함수특성곡선(含水特性曲線)의 측정이 필요하다. 주문진 표준사를 대상으로 pF시험의 흡인법(수두법)과 가압판법을 이용해 함수특성곡선을 구하고 Richard형 불포화투수시험 장치를 개선한 장치에서 glass필터 $P_3$와 $P_4$를 이용하여 불포화투수계수와 함수특성곡선을 구하였다. 또한 대표적인 추정식을 사용하여 표준사에 대한 불포화투수계수와 함수특성곡선을 유도하고 각각의 실험치와 비교 검토하였다. 불포화시험 계측에 없어서는 안될 필터의 선택기준을 제시하고자 필터의 공기침입압(AEV)과 포화투수계수를 측정하여 양자 사이의 상관성을 나타내었다.

• 한국환경보건학회지
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• 제36권5호
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• pp.383-390
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• 2010

Exposure to fugitive dust can contribute to several respiratory health problems, and proper sampling of fugitive dust is necessary to assess exposure. However, field sampling of soil dust encounters problems from spatial and temporal differences in soil properties, field operations, and meteorological conditions. To minimize these problems, we designed a dust generator that simulates dust generation from soil. The dust generator consisted of a rotating chamber where soil samples were loaded and tumbled, and a settling chamber, where airborne soil dust samples were collected. As standard operating conditions, we decided on 2 g soil mass, 10 min sampling time, and 20 rpm rotating speed, with a flow rate of 30 l/min, based on three common soil textures of loam, sandy loam and silt loam. To evaluate optimal operating conditions, we used mixtures of Joomoonjin silica sand and clay. Although the average $PM_{10}$ concentration of Joomoonjin silica sand was low, dust concentrations were increased by an increased content of clay. The dust concentrations were consistent across repeated experiments, and showed similar concentration profiles during the sampling time with mixtures of clay and sand (coefficient of variation was $13.6{\pm}w;7.1%$). The results demonstrated that these standard operating conditions were suitable for the dust generator, which can be used to investigate variations in soil properties that affect dust production and potential potency of fugitive dust exposure.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1998년도 가을 학술발표회 논문집
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• pp.431-438
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• 1998

• 한국지반공학회지:지반
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• 제6권3호
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• pp.41-52
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• 1990

To investigate the liquefaction potential of sands, a series of untrained cyclic triaxial compression tests is carried out on the samples of Ottawa, Joomoonjin, Hn river and Hongseung sands. The constitutive equations of sands are derived to explain the mechanical behavior of sands under cyclic stresses, and are applicable to liquefaction analysis. The following results are obtainded in this study. 1. Sands with the lower confining pressure or relative density are to be easily liquefied, and when the amplitude of cyclic stress are large, liquefaction takes places over only a few cycles. 2. Stress ratio, porewater pressure ratio and cyclic shear strains are to be good criteria to evaluate liquefaction potential of sands. 3. Hongseung sands which contains some silty clay shows higher dynamic properties than other sands. 4. The dynamic behaviors of undisturbed Hongseung sand are about same as those of dense sands. It is noted that undisturbed Hongseung sand shows higher liquefaction potential than the samples made by pluviation under same relative density, 5. The constitutive equations of soils under cyclic loads are developed based on the theory of elasto-plasticity, logarithmic stress-strain rela'tionship, non-associated flow rule and the concept of the boundary surface. The derived equations is applicable to predict the behavior of sands under cyclic loads and liquefaction potential with a higher accuracy. 6. Based on results of the study it may be concluded that cracks of the foundations and dislocation of the structures at Hongseung earthquakes(Oct. 7, 1978, Richter scald 5.2) are not brought by the liquefaction process.

• 한국지하수토양환경학회지:지하수토양환경
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• 제16권6호
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• pp.27-33
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• 2011

Infiltration plays an important role in the urban water cycle. Infiltration has a potential to contribute to groundwater recharge in addition to runoff reduction. However, infiltration in urban areas has been considered only as a means of runoff reduction. Conventional design methods for infiltration facilities assume soils to be fully-saturated for the sake of simplicity. The amount of groundwater recharge can not be estimated properly with this scheme. Hence, the characteristics of the unsaturated soil condition need to be considered. The finite element model using SEEP/W to estimate infiltration under the unsaturated condition is presented. Infiltration tests for Joomonjin sand are performed and the infiltration behavior of Joomoonjin sand under the unsaturated condition is measured experimentally to verify the validity of the finite element model. The results from comparing infiltrated volume between the saturated and the unsaturated conditions under the same soil and rainfall conditions show that the infiltrated volume in the unsaturated condition is two times bigger than that in the saturated condition.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.401-406
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• 2000

Spilling of petroleum hydrocarbons such as gasoline, motor oils, and diesel fuel from underground storage tanks (USTs) is a major source of contamination to ground water and soils. In response to the need of developing an effective and economical cleanup technique, this study investigates the effectiveness of using sonication to enhance the soil flushing method. The study involves laboratory testing, and the testing was conducted using a specially designed and fabricated device to determine the effect of sonication on contaminant removal. The sonication was applied at 20 kHz frequency under different power levels. Test soil was Joomoonjin Sand, and diesel fuel was used as a contaminant of soil flushing test. The results of the investigation show that sonication enhanced the contaminant removal from soils significantly, and the degree of enhancement varied with power levels of sonication. Based on the results of the study, it is concluded that the flushing method with sonication has a great potential to become an effective method for removing petroleum hydrocarbons from the contaminated ground.

• 한국지반공학회논문집
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• 제17권6호
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• pp.193-205
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• 2001

본 연구에서는 수직 및 수평하중을 받는 군말뚝의 배열 및 중심간격을 고려한 실내모형실험을 수행하여 군말뚝기초의 거동특성을 분석하였다. 모형말뚝은 PVC말뚝을 사용하였으며 모형지반은 주문진표준사를 이용해 조밀한 사질토 지반(Dr=73%)으로 조성하였다. 말뚝의 배열은 $2\times2,\; 3\times3$ 배열, 말뚝중심간격은 말뚝직경의 2.5, 5.0, 7.5 배인 경우를 고려하였다. 실험결과 수직하중을 받는 말뚝에서는 두부에서의 수직하중-침하량곡선, 하중전이함수인 주면마찰락력-변위곡선(t-z 곡선)과 선단지지력-변위곡선(q-z 곡선)을 구하였으며, 수평하중을 받는 말뚝에서는 두부에서의 수평하중-수평변위곡선, 하중전이함수인 지반반력-변위곡선(p-y곡선)을 구하였고 이를 토대로 말뚝의 배열 및 중심간격에 따른 군말뚝계수를 제안하였다. 또한 수평하중을 받는 군말뚝의 각 열에 대해 상호작용계수(P-multiplier)를 산정하였다.

• 대한환경공학회지
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• 제27권7호
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• pp.697-703
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• 2005

본 연구에서는 주문진사 입경, 일차 및 이차 코팅온도, 코팅시간, 및 초기 3가철 주입농도를 변화시키면서 철을 코팅시킨 모래흡착제(Iron-Coated Sand, ICS)를 제조하였다. ICS 제조의 최적조건은 코팅효율, 코팅된 철의 안정성, 및 비소제거능 으로부터 선정하였다. 철코팅 효율은 입경이 작은 모래를 지지체로 사용하고 일차코팅온도를 높여주었을 때 뚜렷이 향상되었다. 철의 코팅효율은 이차코팅온도 및 코팅시간에는 크게 영향을 받지 않았지만 As(V) 흡착능은 이차코팅온도가 증가됨에 따라 크게 감소하는 것으로 나타났다. 이러한 결과들을 고려하여 ICS의 최적 이차코팅 조건을 $150^{\circ}C$ 온도조건과 1시간의 가열시간으로 선정하였다. Fe(III) 주입농도 변화에 따른 철 코팅효율은 0.8 Fe(III) mol/kg sand 될 때 까지는 뚜렷이 증가하였지만 그 이상에서는 큰 차이가 없었다. 기리고 Fe(III) 주입농도를 증가시킬수록 As(V) 흡착능도 증가하였으며 0.8 Fe(III) mol/kg sand 조건에서 최대값을 보여주었다. 이차 코팅온도 및 시간은 ICS 안정성의 주요변수로서 코팅온도를 높이고 코팅시간을 길게 할수록 ICS로 부터 용출되는 철의 양은 감소하였다. ICS에 대한 As(V)의 흡착은 낮은 pH에서 흡착량이 증가하는 전형적인 음이온형 흡착경향을 보여서 ICS는 강한 산성을 띄는 오염수내에 함유된 As(V)를 제거하는데 적용이 가능함을 알 수 있었다.