• Journal of the Korean GEO-environmental Society
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• v.17 no.10
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• pp.33-43
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• 2016

The determination of in-situ capping materials is one of the most important factors to design in-situ capping in order to protect capping materials from erosion. Previous studies have established relationship between the velocity induced by wave energy and effective diameter of sediments, but they are mostly empirical and numerical researches which is too complicated for field engineers to analyze the erosion of in-situ capping materials. This study provides simple analytical solutions and reliability based on hydraulic model test results. Experimental results show that measured flow velocities with respect to depth induced by wave energy are almost the same as estimated velocities and the erosion resistances of the different effective particle diameters can be estimated.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.199-206
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• 2003

Particle-size distribution in soils is one of the most fundamental physical properties of soils. One of the latest developments in the study of particle-size distributions has focused on the use of fractal theories. In this study, the fragmentation fractals were used for determining the characteristics of the particle-size distribution curve. It was shown that the mass-size distribution method was more practical than the cumulative number-size distribution method. From the co-relation between fractal dimensions($D_{tot}$) and the coefficient of uniformity($C_{u}$), there was a sharp increase in fractal dimensions for $C_{u}$<4, but fractal dimension converged the single value for $D_{u}$$\geq$6. Fractal dimensions were affected by small sized particles for $C_{c}$$\geq$3 and large sized particles for $C_{c}$/<3. As a result of the analysis of the influence of the effective size($D_{10}$), it was observed that the changes of $D_{tot}$/ were nominal beyond the effective size.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.250-252
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• 2006

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.260-262
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• 2006

• Journal of the Korean Geosynthetics Society
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• v.9 no.1
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• pp.1-11
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• 2010

The soil mechanical characteristics according to geologic conditions were investigated in the study area. The geology of study area was consisted of Ingok Tuff, Yuchi Conglomerate and Dado Tuff. Yuchi Tuff covered about 80% of the study area. The disturbed and undisturbed soils were sampled from the conglomerate area, Tuff area and Shale area, and then a series of the laboratory soil tests was performed. The soils sampled from the conglomerate area have a large dry unit weight and a low permeability relatively, while the soils sampled from tuff and shale areas have a small dry unit weight and a high permeability. It is proven that the soil permeability is highly affected by the effective grain size and the silt and clay content. That is, the soil permeability is increased with increasing the effective grain size, and the soil permeability is decreased with increasing the silt and clay content.

• Journal of the Korean Geosynthetics Society
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• v.5 no.2
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• pp.1-8
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• 2006

The properties of contaminated soil, contaminants and elapsed time are important considering factors to in-situ soil remediation. Gabr et. al. (1996) derived the solution equation of contaminant concentration ratio as initial one ($C/C_0$) with time and spatial changes in contaminated area which are embedded with vertical drains. The contaminant concentration ratio ($C/C_0$) is analyzed with time and spatial changes as varying the effective diameter, porosity, shape factor, density of contaminated soil, temperature in ground, unit weight and viscosity of contaminants by using FLUSH1 model modified from FLUSH. Results from numerical analysis indicate that the most important factor to the in-situ soil remediation in vertical drain system is the effective diameter of contaminated soil. It also shows that the next important factors are the viscosity of contaminants, porosity of soil, shape of soil, temperature in ground, unit weight of contaminants and density of soil, in order. However, the others except the effective diameter of contaminated soil are insignificant to the soil remediation.

• Korean Journal of Weed Science
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• v.31 no.4
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• pp.384-393
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• 2011

Sulfonylurea herbicide-resistant weeds are spreading widely and distributed about 106,951 hectare in paddy rice fields in Korea. Morever all biotype of Scirpus juncoides which were collected at 69 spots all over paddy rice fields in 2008 were identified biotype of sulfonylurea herbicide-resistant. Benzobicyclon is a p-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor, which is absorbed through root and basal stem of weeds so cause bleaching of newly developing leaves. Benzobicyclon was very effective to control Scirpus juncoides, Monochoria vaginalis, sedges and broadleaves weeds, so it have been developed various formulation like a suspension concentrate (SC), a water dispersible granule (WG), a granule (GR) and a DT (tablet for Direct application). During recently 6 years, benzobicyclon-mixtures herbicides have been registered over than 54 products in paddy fields. Herbicidal efficacy by formulations of benzobicyclon and its mixture herbicides were highest in DT, followed by SC and GR. Herbicidal efficacy of the kaolin and $CaCO_3$ carrier of GR was better and stable than that of talc and bentonite carrier. Growth and yield of rice were not affected much by formulations, application rates and rice cultivation methods.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.11
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• pp.1700-1707
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• 2015

The effects of drying temperature on drying characteristics of soybeans with different grain sizes [6.0 (S), 7.5 (M), and 9.0 mm (L) (${\pm}0.2$)] with 25.0% (${\pm}0.8$) initial moisture content were studied. Drying temperatures varied at 25, 35, and $45^{\circ}C$, with a constant air velocity (13.2 m/s). Thin-layer drying models were applied to describe the drying process of soybeans. The Midilli-Kucuk model showed the best fit ($R^2$ >0.99). Based on the model parameters, drying time to achieve the target moisture content (10%) was successfully estimated. Drying time was strongly dependent on the size of soybeans and the drying temperature. The effective moisture diffusivity ($D_{eff}$) was estimated by the diffusion model based on Fick's second law. $D_{eff}$ values increased as grain size and drying temperature increased due to the combined effect of high temperatures and high drying rates, which promote compact tissue. Deff values of S, M, and L estimated were in the range of $0.83{\times}10^{-10}$ to $1.51{\times}10^{-10}m^2/s$, $1.17{\times}10^{-10}$ to $2.17{\times}10^{-10}m^2/s$, and $1.53{\times}10^{-10}$ to $2.95{\times}10^{-10}m^2/s$, respectively, whereas activation energy ($E_a$) based on drying temperature showed no significant differences in the size of soybeans.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.409-413
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• 2011

유효유량이란 수년에 걸쳐 연 유사량의 대부분을 이동시키는 유량으로 정의되며 유량-빈도분포곡선과 유사량 곡선을 이용하여 산정된다. 유효유량은 하도를 설계하거나 기존 하도의 안정성을 평가하는데 있어 기준유량이 될 수 있는 필수적인 요소이지만, 현재 국내의 경우 이에 대한 분석이 충분히 수행되지 않아 특정한 패턴을 도출하기 힘든 실정이다. 특히 우리나라의 하천은 연강수량의 약 70%가 여름철에 집중되는 기후적 특성의 영향으로 하상계수가 미국과 유럽에 비해 10에서 25배 크게 나타나 외국사례를 국내에 적용하는데 어려움이 있다. 따라서 본 연구에서는 구하도복원이 계획 또는 진행되어 유효유량 산정이 필수적이며 하상계수가 매우 큰 만경강, 청미천, 함평천을 대상하천으로 선정하여 유효 유량을 산정하고 수리적, 지형학적 특성과의 연관성을 분석하고자 한다. 유효유량을 계산하는 데 있어 가장 큰 영향을 미치는 요소는 유량빈도 간격 수와 유량빈도 간격의 설정이다. 따라서 본 연구에서는 유효유량 산정을 위한 유량 간격으로 산술등간격(Arithmeic Bin)과 로그간격(Logarithmic Bin)을 모두 사용하였으며 각각 간격수가 25개, 50개, 100개인 경우에 대해 유효유량을 계산하여 비교하였다. 산술등간격과 로그간격을 사용한 유효유량 산정결과 중 최대, 최소값을 제외한 나머지의 평균값을 각 대상하천의 유효유량으로 선정하였다. 수리적, 지형학적 특성에 따른 대상하천 분석 결과 하상계수가 클수록 유효유량이 크게 산정되는 것으로 나타났으며 하상 경사, 하상토의 중앙입경 크기와 비례하는 것으로 나타났다. 반면에 수심-하폭비와 사행도의 경우 유효유량과 반비례하는 것으로 나타났다.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.217.1-217.1
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• 2014

반도체 및 디스플레이 산업은 많은 공정들에서 저온 플라즈마 반응을 이용한다. 특히 소자 제작을 위한 실리콘 박막의 증착은 저온 플라즈마 공정의 주요 공정이다. 하지만 실리콘 박막을 합성하는데 있어서 저온 플라즈마에서 형성되는 실리콘 나노 입자는, 오염입자로써 박막의 특성을 악화시켜 소자생산 수율을 악화시키는 주요 원인이 되고 있다. 따라서 플라즈마에서 입자 형성의 원인이 되는 화학반응 및 입자들의 성장 매커니즘에 대한 연구는, 1980년대 플라즈마 공정에서 입자 합성이 보고된 이래 공정의 최적화를 위해 꾸준히 연구되어왔다. 이러한 매커니즘의 연구들은, 플라즈마 화학반응에 의해 실리콘 입자 핵을 만들어 내는 과정과 입자들이 충돌에 의해 성장해가는 과정으로 나눠진다. 플라즈마 화학 반응 과정은 아레니우스 방정식에 의해 정의된 반응계수를 이용하여 플라즈마 내 전자와 이온, 중성 화학종들이 전자 온도와 전자 밀도, 챔버 온도 등에 의해 결정되는 현상을 모사한다. 또한 이 과정에서 실리콘을 포함하는 화학종들의 반응에 의해 핵이 생성 되가는 양상을 모사한다. 생성된 핵은 충돌에 의해 입자가 성장해 가는 과정의 가장 작은 입자로써 이용된다. 입자들이 성장해가는 과정은 입자들이 서로 충돌하면서 다양한 입경의 입자로 분화되어가는 현상을 모사한다. 이 과정에 의해 다양한 입경분포로 분화된 입자들은 플라즈마 내 전자에 의해 하전되며, 이러한 하전 양상은 입경에 따라 다른 분포를 보인다. 본 연구에서는 입자의 하전 분포를 고려하여, 입자들의 성장의 주요 원인인 입자간의 충돌을 대표하는 충돌주파수를 수정하는 방식을 채택하여 보다 정밀한 입자 성장 양상을 모델링하였다. Inductively coupled plasma (ICP) 타입의 저온 플라즈마 반응기에서 합성된 입자들을 Particle Beam Mass Spectrometer (PBMS)와 Scanning Electron Microscope (SEM)를 이용하여 입경분포를 측정한 데이터와 모델링에 의해 계산된 결과를 비교하여 본 모델의 유효성을 검증하였다. 검증을 위해 100~300 mtorr의 챔버 압력 조건과 100~350 W의 입력 전력 조건들을 달리하며 측정한 결과와 계산한 데이터를 조건별로 비교하였다.