Carboxylated multi-wall carbon nanotubes (MWCNTs-COOH) was functionalized with 3-amino-5-phenylpyrazole (MWCNTs- f) and characterized by FTIR, EDX, SEM, XRD and TGA. The MWCNTs-COOH and MWCNTs-f were used for the adsorption of Cd(II), Hg(II), and As(III) ions from aqueous solutions. Additionally, to study the influence of pH, adsorbent dose, and initial ions concentration on the adsorption process, the central composite design (CCD) was applied. The quadratic model was used for analysis of variance and indicated that adsorption of metal ions strongly depends on pH. Timedependent adsorption can be described by the pseudo-second-order kinetic model, and adsorption process was modeled by Langmuir isotherm for the adsorbents. Thermodynamic analysis showed that the adsorption of Cd(II), Hg(II) and As(III) ions were spontaneous and endothermic. Moreover, the competitive adsorption capacities of the heavy metal ions were slightly lower than noncompetitive ones. The same affinity order was observed under noncompetitive and competitive adsorption: As(III) > Cd(II) > Hg(II) in the case of MWCNTs-f. Desorption study revealed the favorable regeneration ability of adsorbents powders, even after three adsorption–desorption cycles.

The determining the appropriate dosage of coagulant is very important, because dosage of coagulant in the coagulation process for wastewater affects removing the amount of pollutants, cost, and producing sludge amount. Accordingly, in this study, in order to determine the optimal PAC dosage in the coagulation process, CCD (Central composite design) was used to proceed experimental design, and the quadratic regression models were constructed between independent variables (pH, influent turbidity, PAC dosage) and each response variable (Total coliform, E.coli, PSD (Particle size distribution) (‹10 μm), TP, PO4-P, and CODcr) by the RSM (Response surface methodology). Also, Considering the various response variables, the optimum PAC dosage and range were derived. As a result, in order to maximize the removal rate of total coliform and E.coli, the values of independent variables are the pH 6-7, the influent turbidity 100-200 NTU, and the PAC dosage 0.07-0.09 ml/L. For maximizing the removal rate of TP, PO4-P, CODcr, and PSD(‹10 μm), it is required for the pH 9, the influent turbidity 200-250 NTU, and the PAC dosage 0.05-0.065 ml/L. In the case of multiple independent variables, when the desirable removal rate for total coliform, E.coli, TP, and PO4-P is 90-100 % and that for CODcr and PSD(‹10 μm) is 50-100 %, the required PAC dosage is 0.05-0.07 ml/L in the pH 9 and influent turbidity 200-250 NTU. Thus, if the influent turbidity is high, adjusting pH is more effective way in terms of cost since a small amount of PAC dosage is required.

The intent of this research is to apply DOE in mix proportioning of high strength self-compacting concrete (HSSCC) and to assess the effect of different process parameters on HSSCC. The effect of water-binder ratio, cement content, fine aggregate percentage, fly ash content and superplasticizer content on compressive strength, passing ability, and manufacturing cost were studied.

This study investigated the application of experimental design methodology to optimization of conditions of air-plasma and oxygen-plasma oxidation of N, N-Dimethyl-4-nitrosoaniline (RNO). The reactions of RNO degradation were described as a function of the parameters of voltage (X1), gas flow rate (X2) and initial RNO concentration (X3) and modeled by the use of the central composite design. In pre-test, RNO degradation of the oxygen-plasma was higher than that of the air-plasma though low voltage and gas flow rate. The application of response surface methodology (RSM) yielded the following regression equation, which is an empirical relationship between the RNO removal efficiency and test variables in a coded unit: RNO removal efficiency (%) = 86.06 + 5.00X1 + 14.19X2 - 8.08X3 + 3.63X1X2 - 7.66X2 2 (air-plasma); RNO removal efficiency (%) = 88.06 + 4.18X1 + 2.25X2 - 4.91X3 + 2.35X1X3 + 2.66X1 2 + 1.72X3 2 (oxygen-plasma). In analysis of the main effect, air flow rate and initial RNO concentration were most important factor on RNO degradation in air-plasma and oxygen-plasma, respectively. Optimized conditions under specified range were obtained for the highest desirability at voltage 152.37 V, 135.49 V voltage and 5.79 L/min, 2.82 L/min gas flow rate and 25.65 mg/L, 34.94 mg/L initial RNO concentration for air-plasma and oxygen-plasma, respectively.

The aim of this research was to apply experimental design methodology in the optimization condition of electrochemical oxidation of Rhodamine B(RhB). The reactions of electrochemical oxidation were mathematically described as a function of parameters amounts of current, NaCl dosage, pH and time being modeled by the use of the central composite design, which was used for fitting quadratic response surface model. The application of response surface methodology using central composite design(CCD) technique yielded the following regression equation, which is an empirical relationship between the removal efficiency of RhB and test variable in actual variables: RhB removal (%) = 3.977 + 23.279․Current + 49.124․NaCl － 5.539․pH － 8.863 ․time － 22.710․Current․NaCl + 5.409․Current․time + 2.390․NaCl․time + 1.061․pH․time － 0.570․time2. The model predicted also agree with the experimentally observed result(R2 = 91.9%).

수도재배에 있어서 수량은 여러 가지 요인이 복합적으로 작용하여 나타난 반응의 산물이다. 수도의 적정재배조건을 구명하기 위하여 지금까지는 제한된 요인 및 수준에서 시험연구가 수행되어 왔는데, 처리요인수 및 각 요인당 처리수준이 증가될 경우 전체 처리수의 급증으로 시험수행이 어렵게 된다. 본 연구는 이를 극복하고자 조생량 벼 품종 '운봉벼'의 재식주수, 주당본수, 질소시비량, 이앙일, 육묘일수 등 5가지 계량적 재배요인의 최적조건을 구명하기 위한 시험을 수행하고 수량을 Box와 Wilson의 중심합성계획법에 따라 분석하였으며(시험 1), 같은 품종을 공시하여 실험 1과 같은 요인을 Finney의 부분실시법(FFD)과 비교함으로써(시험 2) CCD의 농사시험연구에의 활용가능성을 제시하고자 하였다. 1. 재배조건에 따른 수량반응 수량은 5요인중 4요인의 수준을 중심수준에서 통제하였을 때 각 요인별 최대수량은 중심수준(재식주수, 90수/3.3m2 ; 주당본수, 5본 ; N시비량, 11kg/10a ; 이앙일, 6월 25일 ; 육묘일수, 35일) 부근이었고 각 요인이 양극단수준으로 갈수록 감수하였으며 5요인중 3요인을 중심수준에서 통제하고 난 뒤에 2요인들 간의 상호작용에 의한 수량은 가 수준의 중심부에서 최고치를 보였다. 전체 5개 요인의 상호작용에 의해 나타난 수량의 정상점은 안부점이었다. 2. 두 계획법의 비교 가. CCD에서 수량에 대한 각각의 정상점에서의 재배조건은, 재식주수 107주/3.3m2 , 주당본수 4본, 질소시비량 10kg/10a, 이앙일 6월 26일, 육묘일수 33일이었고, 정상점에서의 수량은 439kg/10a으로서 FFD에서의 그것들과 비슷하였다. 나. CCD에 의하면 요인수와 수준수가 많아도 처리조합수를 획기적으로 줄일 수 있었고, 실험재료의 절적, 작업시간의 단축 및 작업의 간편화를 가져왔다. 다. CCD(각 요인별 5수준)는 FFD(각 3수준)에 비하여 수준수가 많았지만 결과를 도해화하기에 편리하였다. 라. 양 계획법에 있어서 수량의 정상점이 안부점인 것으로 보아 요인의 설정시 각 요인 상호간의 이질성을 고려해야 하며, 처리요인의 지나친 증가도 억제되어야 할 것이다. 마. CCD는 극한수준(± 2, ± 2, ± 2, ± 2, ± 2)의 처리가 없기 때문에 각 요인의 극한수준의 실험영역에 대해서는 적은 정보를 얻었으나. FFD보다는 많은 유익한 정보를 획득할 수 있었다. 따라서, CCD는 획기적으로 처리수를 줄였어도 유익한 정보를 제공하는 것으로 보아, 농사시험연구에 효율적으로 활용할 수 있는 계획적으로 확인되었다.적으로 확인되었다.