• Korean Chemical Engineering Research
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• 제43권4호
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• pp.458-466
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• 2005

회분식 증류 공정을 모델링하기 위해서는 평형상수와 엔탈피값이 필요하며 이 값들은 열역학적인 계산 방법에 의해 계산된다. 석탄 유분인 coal tar의 경우에는 성분이 다양하고 coal tar내의 성분을 대부분 알 수 없으므로 가상성분으로 만들어 적절한 물성예측식을 사용하여 물성값을 계산해 주어야 한다. 본 연구에서는 기존의 물성예측식에 의해 계산된 값과 이미 알려진 coal tar 유분의 실제물성값의 차이를 기 개발된 물성예측식에 대해 비교하였고 물성예측식에 필요한 2개의 parameter(NBP, SG)대신 1개의 변수(NBP)를 사용하여 간단한 물성예측식을 도출하였다. 또한 이상 기체 열용량 예측식의 경우에도 같은 방법을 적용하였다. 개발된 물성 예측식 및 회분식 증류공정프로그램은 coal tar계에 적용하여 coal tar 중 유효성분 분리를 위해 효율적으로 적용할 수 있다 하겠다.

• Macromolecular Research
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• 제14권4호
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• pp.456-460
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• 2006

The electrical, morphological, and mechanical properties of poly carbonate (PC)/multi-walled carbon nan-otube (MWNT) composites were studied by electrical conductivity, electromagnetic interference shielding efficiency (EMI SE), scanning electron microscopy, and tensile strength measurements. In the electrical property analysis of the PC/MWNT composites, the percolation threshold of the PC/MWNT composites was observed between 1.5 and 2.5 wt% MWNT content. From the electrical conductivity and EMI SE studies, the theoretical values of the EMI SE were in good agreement with the experimental values of the EMI SE. From the morphology of the PC/MWNT composites, it was observed that MWNT is dispersed homogenously in the PC matrix. From the electrical conductivity and morphological studies, it was suggested that the percolation threshold of the PC/MWNT composites is related with the morphological results in that MWNT is apparently interconnected to form an electrical pathway. The mechanical properties of the PC/MWNT composites peaked at the MWNT content of 2.5 wt%.

• 한국토양비료학회지
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• 제50권1호
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• pp.56-64
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• 2017

Soil quality has been regarded as an important factor for maintaining sustainability of ecosystem. Main purpose of this research was i) to select minimum factor for predicting biomass, and ii) to calculate soil quality index for biomass according to soil chemical properties. Result showed that soil pH, electrical conductivity (EC), soil organic matter (SOM), cation exchange capacity (CEC), and available phosphorus are minimum data set for calculating biomass production in soil. Selected representative soil chemical properties were evaluated for soil quality index and rated from 1 to 5 (1 is the best for biomass production). Percentage of each grade in terms of biomass production in national wide was 14.52, 35.23, 33.03, 6.47, 10.75% respectively. Although, only soil chemical properties were evaluated for calculating optimum soil quality, result of this research can be useful to understand basic protocol of soil quality assessment in national wide.

• 한국지하수토양환경학회지:지하수토양환경
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• 제24권2호
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• pp.8-22
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• 2019

Among numerous chemicals used globally, the number of emerging contaminants is increasing. Numerical modeling for contaminant fate and transport in the subsurface is critical to evaluate environmental and health risk. In general, such models require physicochemical properties of contaminants as input values, which can be found in numerous chemical databases (DB). However, there exist lack of information specific to recently emerging contaminants, which requires estimation of physicochemical properties using regression programs. The purpose of the study is to introduce the workflow for identifying physicochemical properties of potential contaminants utilizing numerous chemical DBs, which frequently lists up potential contaminants for estimating chemical behavior. In this review paper, details of several chemical DBs such as KISChem, TOXNET, etc. and regression programs including EPI $Suite^{TM}$, ChemAxon, etc. were summarized and also benefit of using such DBs were explained. Finally, a few examples were introduced to estimate predominant phase, removal ratio, partitioning, and eco-toxicities by searching or regressing physicochemical properties.

• Bulletin of the Korean Chemical Society
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• 제31권5호
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• pp.1237-1240
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• 2010

The mechanical properties of multiwalled carbon nanotubes (MWNTs)-reinforced epoxy matrix composites with different weight percentages of MWNTs have been investigated. Also, the morphologies and failure behaviors of the composites after mechanical tests are studied by SEM and TEM analyses. As a result, the addition of MWNTs into the epoxy matrix has a remarkable effect on the mechanical properties. And the fracture surfaces of MWNTs/epoxy composites after flexural strength tests show different failure mechanisms for the composites under different nanotube contents. Also, a chemical functionalization of MWNTs can be a useful tool to improve the dispersion of the nanotubes in an epoxy system, resulting in increasing the mechanical properties of the composite materials studied.

• Journal of Biosystems Engineering
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• 제24권5호
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• pp.407-414
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• 1999

To evaluate the quality of flame-peeled chestnuts, their physical and chemical properties were analyzed. The physicochemical properties of flame-peeled chestnuts, including geometrical shape, texture and chemical composition, were compared to those of hand-peeled ones. For the flame-peeled chestnuts, some properties in heated and non-heated sections were separately analyzed. The color, texture such as springness, cohesiveness, adhesiveness, hardness and chewiness, moisture content, and reducing sugar of the heated section of the flame-peeled chestnuts were significantly different with their non-heated section. But the physicochemical properties of the non-heated section of the flame-peeled chestnuts were similar to those of the hand-peeled ones.

• 한국토양비료학회지
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• 제45권2호
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• pp.209-214
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• 2012

과수원에서 화학비료 대체 가능성을 검토하기 위하여 5년 동안 SCB 액비 사용했을 때 배나무 잎의 무기성분 함량, 과실 특성 및 수량, 토양 화학성에 미치는 영향은 다음과 같다. SCB 액비와 화학비료 시용에 따른 배나무 잎의 무기 성분함량은 처리 간에 차이가 없었다. 과실 특성 중 과중, 산도와 수량은 처리 간에 유의성이 없으나 질소 기준으로 SCB 액비를 처리했을 때 과중이 큰 경향을 보였고 당도는 액비 처리구가 화학비료 처리구보다 높았다. SCB 액비 시용에 따른 토양 화학성 변화는 화학비료 처리에 비하여 pH가 높았으나 유기물, 유효인산, 치환성 양이온은 화학비료 처리와 같은 경향을 보였다. 결과를 종합하면 SCB 액비는 토양 분석에 의한 질소 기준량을 시용하여도 배나무 및 토양 화학성에 미치는 영향이 화학비료와 대등하여 화학비료 대체가 가능할 것으로 판단되었다.

• 한국의류산업학회지
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• 제15권3호
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• pp.430-436
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• 2013

The purpose of this study investigates the effects of electron beam(EB) irradiation on the chemical and morphological properties of Hansan ramie fiber. Hansan ramie fibers were irradiated with electron beam doses of 0, 1, 3, 5 and 10kGy. The effect of electron beam irradiation on the chemical components of fibers as well as the surface chemical and morphological properties were investigated using chemical component analysis methods based on TAPPI standards, XPS, and SEM. The results indicate that the surface layers can be removed under suitable EB irradiation doses. Alcohol-benzene extraction and lignin content increases gradually with an increase in EB irradiation and reaching a maximum at an EB dose of 3kGy, and decreases at 10kGy. The surface chemical changes measured by XPS corresponded to the chemical composition analysis results. The C1 peak and the O/C ratio decreased with the removal of the multi-layer and primary layer by EB irradiation. The SEM images show the inter-fibrillar structure etched by EB irradiation up to 5kGy. At 10kGy, the surface structure of the ramie fiber shows highly aligned and distinctive striations in a longitudinal direction. The removal of these exterior layers of the fiber was confirmed by changes in surface morphology as observed in SEM images.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 토목섬유 학술발표회 논문집
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• pp.39-55
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• 1999

Geotextile composites to improve the weather ability were composed of recycled polyester geotextile with carbon black as ultraviolet stabilizer and polypropylene geotextile by needle-punching method, and evaluated physical properties, ultraviolet resistance and chemical stability. Retention ratio of tensile properties of non woven polypropylene geotextiles were decreased about 50% by the exposed condition with ultraviolet but those of geotextile composites were slightly decreased than polypropylene geotextiles. Geotextile composites which have larger weights of polyester geotextile were more stable against ultraviolet. For chemical stability, the changes of tensile properties of geotextile composites were in the range of -20~＋10% at the various chemical conditions.

• Journal of Ecology and Environment
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• 제30권1호
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• pp.39-47
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• 2007

The relationships between the cover of herbaceous species and 15 soil chemical properties (organic carbon contents, total N, available P, exchangeable K, Na, Ca and Mg, HCl-extractable Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in nine poorly controlled waste landfill sites in Korea were examined by correlation analysis and multiple regression equations. Species showed different patterns of correlation between their cover values and soil chemical properties. The cover of Ambrosia artemisiifolia var. elatior, Aster subulatus var. sandwicensis and Erechtites hieracifolia were negatively correlated with the contents of Fe, Mn and Ni within landfill soils. Total cover of all species in quadrats was positively correlated with the contents of Cd and negatively correlated with the contents of Mn and Fe from stepwise regression analysis with 15 soil properties. Canonical correspondence analysis demonstrated that the distribution of native and exotic plants on poorly controlled landfills was significantly influenced by the contents of Na and Ca in soils, respectively.