• Computers and Concrete
• /
• 제28권6호
• /
• pp.635-642
• /
• 2021

In this paper, soft learning techniques are used to predict the ultimate torsional capacity of Reinforced Concrete beams strengthened with Fiber Reinforced Polymer. Soft computing techniques, namely Artificial Neural Network, trained by various back propagation algorithms, and Particle Swarm Optimization (PSO) algorithm, have been used to model and predict the torsional strength of Reinforced Concrete beams strengthened with Fiber Reinforced Polymer. The performance of each model has been evaluated by using statistical parameters such as coefficient of determination (R²), Root Mean Square Error (RMSE), and Mean Absolute Percentage Error (MAPE). The hybrid PSO NN model resulted in an R² of 0.9292 with an RMSE of 5.35 for training and an R² of 0.9328 with an RMSE of 4.57 for testing. Another model, ANN BP, produced an R² of 0.9125 with an RMSE of 6.17 for training and an R² of 0.8951 with an RMSE of 5.79 for testing. The results of the PSO NN model were in close agreement with the experimental values. Thus, the PSO NN model can be used to predict the ultimate torsional capacity of RC beams strengthened with FRP with greater acceptable accuracy.

• Journal of Forest and Environmental Science
• /
• 제28권2호
• /
• pp.63-67
• /
• 2012

Crown ratio is the ratio of live crown length to tree height. It is often used as an important predictor variable for tree growth equation. It indicates tree vigor and is a useful parameter in forest health assessment. The objective of the study was to develop crown ratio prediction models for Tectona grandis. Based on the data set from the temporary sample plots, several non linear equations including logistics, Chapman Richard and exponential functions were tested. These functions were evaluated in terms of coefficient of determination ($R^2$) and standard error of the estimate (SEE). The significance of the estimated parameters was also verified. Plot of residuals against estimated crown ratios were observed. Although the logistic model had the highest $R^2$ and the least SEE, Chapman-Richard and Exponential functions were observed to be more consistent in their predictive ability; and were therefore recommended for predicting crown ratio in the stand.

• Advances in environmental research
• /
• 제3권2호
• /
• pp.131-149
• /
• 2014

Two different model selection indices, the Akaike information criterion (AIC) and the coefficient of determination ($R^2$), are used to discriminate competing isotherm equations for aqueous pollutant removal systems. The former takes into account model accuracy and complexity while the latter considers model accuracy only. The five types of isotherm shape in the Brunauer-Deming-Deming-Teller (BDDT) classification are considered. Sorption equilibrium data taken from the literature were correlated using isotherm equations with fitting parameters ranging from two to five. For the isotherm shapes of types I (favorable) and III (unfavorable), the AIC favors two-parameter equations which can easily track these simple isotherm shapes with high accuracy. The $R^2$ indicator by contrast recommends isotherm equations with more than two parameters which can provide marginally better fits than two-parameter equations. To correlate the more intricate shapes of types II (multilayer), IV (two-plateau) and V (S-shaped) isotherms, both indices favor isotherm equations with more than two parameters.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2008년도 학술발표회 논문집
• /
• pp.2244-2248
• /
• 2008

This study was focused on estimated Stream Maintenance Flow and performed for simulate securing Stream Maintenance Flow in New town development area. Tributary streams were made of 6 small streams, joined Gong-ji Stream and Eu-am lake finally. For estimate Stream Maintenance Flow used Kajiyama and SWAT models for calculate available flow in study area. As a result the annual average stream flow dry years were $2,300{\sim}136,000\;m^/day3$, the annual average stream flow wet years were $4,800{\sim}136,031\;m^3/day$. The coefficient of determination($R^2$) and Nash-sutcliffe coefficient(EI) for comparison between Kajiyama and SWAT models were 0.88, 0.78 respectively.

• 분석과학
• /
• 제26권2호
• /
• pp.142-153
• /
• 2013

Milbemycin계 속효성 살충제인 lepimectin의 국내 잔류허용기준이 신설 고시됨에 따라 농산물 중 lepimectin 잔류량을 측정하기 위해 고성능 액체크로마토그래프를 이용한 신속, 정확한 분석법을 개발하였다. Lepimectin 잔류물은 메탄올로 추출하여 포화식염수와 디클로로메탄을 이용한 액액분배를 수행하였고, 플로리실로 충진한 유리칼럼 및 아미노프로필 카트리지를 이용하여 두 번의 정제 과정을 거친 후 HPLC-PAD (High performance liquid chromatograph-photodiode array detector)를 통해 기기분석을 수행하였으며, LC-MS (Liquid Chromatograph-Mass Spectrometer)로 재확인하였다. Lepimectin 표준품의 직선성은 lepimectin $A_3$, $A_4$ 모두에서 상관계수($R^2$)가 0.9999로 우수하였다. 개발한 분석법으로 오이, 고추, 현미, 감귤, 감자, 대두에 대한 lepimectin의 회수율을 측정한 결과, 76.0~114.8% 범위로 10% 미만의 표준오차를 나타내었으며, 분석법의 검출한계는 0.005 mg/kg, 정량한계는 0.01 mg/kg이었다. 또한 광주지방식약청, 대전지방식약청의 분석법 검증 결과, 각각 70.3~108.8%, 80.5~95.6%의 회수율과 10% 미만의 표준 오차를 나타내었다. 분석법에 대한 각 실험실의 회수율과 표준오차 및 실험실간 표준 오차($RSD_R$; Relative Standard Deviation on Reproducibility)는 코덱스 기준(CAC/GL 40)에 적합함을 확인하였다. 따라서 본 연구에서 개발된 분석법은 lepimecin 잔류물의 안전관리를 위한 최적의 분석법으로 판단된다.

• 환경위생공학
• /
• 제19권1호
• /
• pp.37-41
• /
• 2004

The removal efficiency of cadmium by chitosan complex isolated from Aspersillus oryzae was investigated through laboratory experiments. The results of the study are as follows. The adsorption kinetics of cadmium was reached the adsorption equilibrium in approximately 20 minutes and the removal efficiency was showed 95.8%. The effect of temperature on cadmium adsorption by chitosan complex shows that as the temperature increased, the amount of cadmium adsorption per unit weight of chitosan complex increased. The correlation between amount of cadmium adsorption per unit weight of chitosan complex and temperature was obtained through the coefficient of determination($R^2$). $R^2$ values was 0.854(p<0.05). A linearized Freundlich equation was used to fit the acquired experimental data. As a result, Freundlich constant, the adsorption intensity(1/n) was 0.550, and the measure of adsorption(k) was 2.181. So, it was concluded that adsorption of cadmium by chitosan complex is effective.

• 분석과학
• /
• 제20권1호
• /
• pp.55-60
• /
• 2007

A sensitive technique for the determination of trace Cu(II) in various samples after the column preconcentration by adsorbing its N-benzoylphenylhydroxylamine (BPHA) onto benzophenone was developed. Several experimental conditions such as the pH of the sample solution, the amount of chelating agent, the amount of benzophenone, and the flowrate of sample solution and so forth were optimized. The interfering effects of diverse concomitant ions were investigated. Fe(III) and $CN^-$ interfered with more seriously than any other ions. However, the interference by these ions could be overcome sufficiently by adjusting the added volume of 0.01M BPHA to 10 mL. The dynamic range, the correlation coefficient ($r^2$) and the detection limit obtained by this proposed technique were 5.0~120 ng/mL, 0.9974, and 2.1 ng/mL, respectively. For validating this proposed technique, the aqueous samples (stream water, reservoir water, and wastewater), the plastic sample and the diluted brass sample were used. Recovery yields of 93~102% were obtained. These measured data were not different from ICP-MS data at 95% confidence level. This method was also validated by the rice flour CRM (normal, fortified) samples. Based on the results from the experiment, it was found that this proposed technique could be applied to the determination of Cu(II) in various real samples.

• Journal of Photoscience
• /
• 제12권3호
• /
• pp.149-153
• /
• 2005

A chemiluminescence (CL) method for the determination of ascorbic acid was proposed, which is based on the enhancement of the CL intensity of $Ru(bipy)_3^{2+}$ - Ce (IV) system with the addition of ascorbic acid. The CL intensity is proportional to the concentration of ascorbic acid in the range of $1{\times}10^{-10}\;to\;1{\times}10^{-5}M$ with a correlation coefficient of 0.9985. The detection limit is $3{\times}10^{-11}M$. The relative standard deviation (R.S.D.) of 10 determinations of 0.1 mM ascorbic acid was 1.75%. The proposed method has been successfully applied to the determination of ascorbic acid in the commercia] drinks. The possible mechanism of the CL reaction was studied.

• Mass Spectrometry Letters
• /
• 제14권2호
• /
• pp.36-41
• /
• 2023

A simple method was developed to determine residual p-arsanilic acid (ASA), an organo-arsenic compound used as a feed additive, in aquatic products (eel, halibut, and shrimp) using EDTA-assisted solvent extraction and LC-MRM. The method was successfully validated in terms of specificity, linearity (coefficient of determination ≥ 0.995), accuracy (recovery or R, 72.72-78.73%), precision (the relative standard deviation of R, 2.08-6.98%), and sensitivity (the lower limit of quantitation, 5 ppb) according to CODEX guidelines (CAC-GL 71-2009). The use of EDTA in the extraction solvent and water with a suitable pH modifier as the reconstitution solvent may be the key factors for successful results. This is the first method that can be used for monitoring residual ASA in aquatic products using LC-MRM and could contribute to establishing a better aquatic product safety management system.

• 한국물환경학회지
• /
• 제28권6호
• /
• pp.882-889
• /
• 2012

This study has evaluated the trophic state in Daecheong Lake by Carlson (1977) method, Aizaki (1981) method, Yang and dickman (1993) method, and Korean trophic state index method. For estimating the trophic state index from each analysis method we use water quality factors such as COD, TN, TP, Chl-a, and SD provided by the water information system and the ministry of environment. The seasonal lake trophic state results denote the mesotrophic state lake from Carlson (1977) method, Aizaki (1981) method, and Korean trophic state index method and the high relation between Carlson (1977) method and Aizaki (1981) method with the coefficient of determination $R^2$ greater than 0.9 for all the seasons. Although Korean trophic index method has relatively weak relation to other methods with the coefficient of determination $R^2$ ranging from 0.419 to 0.701, we propose that Korean trophic index method is suitable for use in domestic lakes since Korean trophic index results show the similar periodicity and tendency with other method results. Hence, Korean trophic index method incorporating domestic lake characteristics is expected to can contribute to seasonal water quality management measures in lakes.