• Resources Recycling
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• v.20 no.6
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• pp.28-36
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• 2011

The adsorption of nickel(Ni) from sulfuric acid solution was carried out by ion exchange method. A series of batch tests in synthetic solutions were carried out using Lewatit Monoplus TP 220 resin. The following experimental parameters, such as temperature, shaking rate, reaction time, pH, resin dosage and concentration of nickel ions etc. were investigated to establish the effective optimum conditions of nickel adsorption. The solution pH(2.0~5.0) and shaking rate had little effects on the adsorption of nickel and adsorption time of 72hours was required to reach equilibrium. The experimental results show a good agreement with Feundlich isotherm and pseudo-second order reaction. The adsorption behavior of Ni obtained from synthetic solution was compared with that of waste electroplating solution. Elution of nickel from loaded resin increased with increase in $H_2SO_4$ concentration.

• Clean Technology
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• v.21 no.3
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• pp.164-170
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• 2015

In this study, polysulfone-Escherichia coli biomass composite fiber (PSBF) was prepared by spinning the suspension of PS and E. coli biomass and amine-methylated PSBF (AM-PSBF) was fabricated through the methylation of amine groups in PSBF. As comparing the adsorption characteristics of basic dye, Basic Blue 3 (BB3) by the PSBF and AM-PSBF, the effect of the methylation of amine groups on BB3 adsorption was confirmed. pH edge experiments showed that the BB3 uptake of PSBF and AM-PSBF increased as pH was increased and the BB3 uptake of AM-PSBF was higher than that of PSBF at the same pH. Both of PSBF and AM-PSBF was reached at equilibrium within 5 h and kinetic experimental data were well fitted by the pseudo-first-order kinetic model. By the Langmuir model, the maximum adsorption capacities of PSBF and AM-PSBF at pH 8 were evaluated to be 28.9 and 20.7 mg/g, respectively. The maximum adsorption capacity of AM-PSBF was enhanced 1.4 times comparing that of PSBF. These results indicate that the methylation of amine groups in PSBF leads to the improvement of BB3 adsorption capacity. In addition, the results of desorption experiments revealed that AM-PSBF was repeatedly reusable.

• Journal of Korean Society of Forest Science
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• v.106 no.4
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• pp.480-486
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• 2017

This study was conducted to develop the merchantable stem volume models to predict the volume up to upper diameter or upper height out of the total stem volume, targeting on Pinus densiflora, Pinus koraiensis, and Larix kaempferi in South Korea. The 131 stemmed sample trees for stem analysis were used as the data for developing the models. The six kinds of merchantable volume equations including merchantable volume ratio form, ratio form, and exponential ratio form were examined to develop the best models. The two models were finally selected as the best models to predict the merchantable volume: $V_d=V_t\{{\exp}[{\alpha}_1(d^{{\alpha}_2}/D^{{\alpha}_3})]\}$ for upper diameter and $V_h=V_t\{1+{\beta}_1(P^{{\beta}_2}/H^{{\beta}_3})\}$ for upper height. By rearranging the best model equations, implicit taper functions were derived, and the estimation was performed for the upper height by upper diameter and upper diameter by upper height. Because of not only the high accuracy but also the convenience, the models developed in this study were considered to be easily applicable in the field of forestry.

• Journal of the Korean GEO-environmental Society
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• v.14 no.5
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• pp.57-63
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• 2013

In this study, the characteristics of degradation and mineralization of diazinon using a statistical approach based on Box-Behnken design (BBD, one of response surface method) was investigated in an E-beam process, and also the main factors with diazinon concentration ($X_1$), irradiatin intensity ($X_2$) and pH ($X_3$) which consisted of 3 levels in each factor was set up to determine the effects of factors and optimization. At first, effects of pH and diazinon concentration were investigated to determine the proper range of application on response surface method(RSM). In statistical approach, the regression analysis and analysis of variance (ANOVA) were applied to evaluate the quantitative comparison of each factors in order to obtain the effects were irradiation intensity>diazinon concentration>pH. The regression model predicted the optimization point using the response optimizer to consider the effects of operation conditions were $Y_1=81.73-5.58X_1+23.69X_2-14.23X{_2}^2+4.22X{_3}^2(R^2=99.7%)$, $Y_2=35.23-3.01X_1+10.79X_2-7.58X_2{^2}(R^2=97.9%)$ and 95.7% of diazinon degradation, 41.8% of TOC reduction at 12.75mg/L and 4.26kGy, respectively. The pH condition was not significantly affects on E-beam process than other advanced oxidation processes (AOPs).

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.416-416
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• 2019

육상 담수는 대기중 이산화탄소($CO_2$) 배출의 중요한 발생원으로 주목되고 있다. 하천 및 강에서 대기중으로 배출되는 $CO_2$는 전 세계 탄소순환의 핵심요소이며, 대부분의 하천과 강은 $CO_2$로 과포화 되어있다. 세계적으로 하천 및 강의 $CO_2$ 배출량은 호수 및 저수지의 배출량보다 약 5배 많은 것으로 보고되고 있으나, 국내연구에서는 연구사례가 드물다. 따라서 본 연구의 목적은 낙동강 중하류에 위치해있는 강정고령보(GGW), 달성보(DSW), 합천창녕보(HCW), 창녕함안보(CHW)에서 발생되는 순 대기 배출 플럭스(Net Atmospheric Flux, NAF)의 동적 변동 특성을 분석하고, 데이터마이닝 기법을 적용하여 쉽게 수집할 수 있는 물리적 및 수질 변수로 $CO_2$ NAF를 추정하는데 사용할 수 있는 간략한 예측 모델을 개발하는데 있다. $CO_2$ NAF는 대기-수면 경계면에서의 $CO_2$ 부분압($pCO_2$)의 차에 기체전달속도를 곱하여 산정하였으며, 기체전달속도는 Cole and Caraco(1998)가 제안한 식을 사용하였다. 담수와 해수의 탄산염 시스템에서 열역학적 화학평형을 모두 고려한 $CO_2$SYS 프로그램을 사용하여 수중의 $pCO_2$를 산정하였고, $CO_2$ NAF는 Henry의 법칙과 Fick의 1차 확산법칙을 사용하여 계산하였다. $CO_2$ NAF의 시간적 변동성에 영향을 미치는 환경요인을 평가하기 위해서 상관분석, 주성분분석(Principal Component Analysis; PCA), 단계적다중회귀모델(Step-wise Multiple Linear Regression; SMLR), 랜덤포레스트(Random Forest; RF)방법을 사용하였다. SMLR 모델은 R package인 olsrr, RF 모델은 R package인 caret, randomForest를 이용하여 분석하였다. 연구 결과, 4개 보 상류 하천구간은 조류의 성장이 활발한 일부 기간을 제외한 대부분의 기간에서 $CO_2$를 대기로 배출하는 종속영양시스템(Heterotrophic system)을 보였다. $CO_2$ NAF의 중위값은 HCW에서 최소 $391.5mg-CO_2/m^2day$, DSW에서 최대 $1472.7mg-CO_2/m^2day$였다. 모든 보에서 NAF는 pH와 강한 음의 상관관계를 보였으며, $pCO_2$와 Chl-a도 음의 상관관계를 보였다. 이는 조류가 수중에서 $CO_2$를 소비하고 pH를 증가시키기 때문이다. PCA 분석 결과, NAF와 $pCO_2$가 높은 공분산을 보였으며, pH와 Chl-a는 반대 방향으로 군집되어 상관분석과 동일한 결과를 보였다. 이 연구를 통해 개발된 SMLR 모델과 RF 모델의 Adj. $R^2$ 값은 모든 보에서 0.77 이상으로 나왔으며, $pCO_2$ 측정 데이터가 없더라도 하천의 $CO_2$ NAF를 추정하는 방법으로 사용될 수 있을 것으로 평가된다.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.10
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• pp.568-574
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• 2017

The purpose of this study was to optimize experimental conditions (time ($X_1$) (ranging of 26.36 - 93.64 min), concentration of sulfuric acid ($X_2$) (ranging of 0-2.5%) and temperature ($X_3$) (ranging of $136.4-203.6^{\circ}C$) for an organosolv pretreatment process to extract lignin from waste wood. The resulting quadratic model equation using RSM (response surface methodology) represented y (lignin yield) = $-79.89+0.91X_1+9.8X_2-2.54{\times}10^{-3}X_1{^2}-2.11X_2{^2}$. The $R^2$ (coefficient of determination) value of 0.8531 for a model indicates this model has statistically significant predictors at the 10% levels. The predictive results optimized by quadratic model produced a lignin yield of 12.46 g/100 g of dry wood under conditions of $178.2^{\circ}C$ and 2.32% $H_2SO_4$. The lignin yield was more affected by the acid catalyst concentrations than the reaction temperature, but the reaction time was not an influential factor for improving lignin extraction from waste wood in this organosolv pretreatment. According to ANOVA (analysis of variance), the significance probability (p-value) of model was smaller than 0.001 and simulation of obtained model equations showed a good reproducibility based on actual organosolv tests under optimal conditions.

• Journal of the Korean Geotechnical Society
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• v.16 no.6
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• pp.95-95
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• 2000

(No Abstract.see full/text)

• Journal of the Korean Geotechnical Society
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• v.16 no.6
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• pp.97-103
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• 2000

지반내 중금속의 저류와 이동에 대한 가장 중요한 인자는 토양 간극수의 pH이다. 점토의 완충능을 kaolinite, hectorite, attapulgite, Na-bentonite와 같은 4가지 점토에 대하여 연구하였다. 완충능의 크기는 hectoriteattapulgite>kaolinite의 순으로 나타났다. 완충능의 크기는 지반내 탄산염 함량과 양이온 교환능력이 완충능의 크기에 가장 영향을 미치며 유기물 함량과 비표면적의 영향은 적었다. 토양의 완충능을 모델링하기 위하여 수소 이온과 토양표면의 화학반응 기간의 화학반응을 정전흡착 모델을 이용하여 모델링하였다. 또한 탄산염 함량과 양이온 교환능력을 함수로 하는 회귀식을 제안하였다. 모델 검증을 위하혀 모델 예측치와 실험치를 비교하였는데 정전 흡착모델을 이용한 예측치가 실험치와 근사한값을 나타냈다.

• Korean Journal of Food Science and Technology
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• v.43 no.3
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• pp.303-314
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• 2011

The purpose of this study was to determine the optimal mixing conditions for two different amounts of added mulberry powder and fresh cream to prepare functional chocolate with added mulberry powder. The experiment was designed according to the central composite response surface design, which showed 10 experimental points, and included two replicates for mulberry powder and fresh cream. The physiochemical, mechanical, and sensory properties of the test were measured, and these values were applied to the mathematical models. The results of the physiochemical and mechanical analyses of each sample, including pH, moisture content, total phenolic content, DPPH free radical scavenging activity, color L, color b, hardness, gumminess, and cohesiveness showed significant differences. The sensory characteristics of the samples tested were significantly different in flavor, texture, sourness, bitterness, and overall acceptability. The optimum formulation calculated by numerical and graphical methods was 25.76 g mulberry powder and 72.21 g fresh cream.

• Journal of the Korea Organic Resources Recycling Association
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• v.22 no.2
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• pp.27-34
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• 2014

Kinetic and isotherm properties of the cadmium adsorption onto calcium sand and granite soil were evaluated by batch experiments. The pHs of calcium sand and granite soil were 9.51 and 6.33, respectively, showing that the precipitation of heavy metals can be occurred due to the increase of pH when the calcium sand is used as an adsorbent. The pseudo-second-order model described the adsorption kinetics satisfactory with correlation coefficients over 0.999. The equilibrium adsorption capacities of calcium sand and granite soil were 2.10 and 2.16 mg/g, respectively. The adsorption isotherm followed the Freundlich isotherm model, indicating the cadmium adsorbed onto the heterogeneous surfaces of adsorbents.