• Journal of the Korean Society of Safety
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• v.32 no.1
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• pp.27-32
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• 2017

The experimental design methodology was applied in the real scale coal-fired boiler to predict the various combustion properties according to the operating conditions and to assess the coal plant safety. Response surface method (RSM) was introduced as a design of experiment, and the database for RSM was provided with the numerical simulation of the coal-fired boiler. The three independent variables, high heating value of coal (HHV), overall stoichiometry excess air ratio (OST), and burner-side stoichiometry excess air ratio (BST), were set to characterize the cross section averaged NOx concentration and temperature distribution. The maximum NOx concentration was predicted accurately and mainly controlled by BST in the boiler. The parabola function was assumed for the zone averaged peak temperature distribution, and the prediction was in a fairly good agreement with the experiments except downstream. Also, the location of the peak temperature was compared with that of maximum NOx, which implies that thermal NOx formation is the main mechanism in the coal-fired boiler. These results promise the wide use of statistical models for the fast prediction and safety assessment.

• International Journal of Control, Automation, and Systems
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• v.5 no.1
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• pp.104-109
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• 2007

This paper is about a redundancy management system design for the Smart UAV(unmanned aerial vehicle) which utilizes the tilt..rotor mechanism. In order to meet the safety requirement on the PLOC(probability of loss of control) of $1.7{\times}10^{-5}$ per flight hour for FCS (flight control system) failures, a digital FCS is mechanized with a dual redundant structure. A fault detection system which is composed of a CCM(cross channel monitor) and analytic redundancy using the Kalman filtering is designed, and its effectiveness is evaluated through experiments. A threshold level and persistence count for managing redundant sensors are designed based on the statistical analysis of the FCS sensors. To increase the survivability of the UAV after the loss of critical sensors in the SAS(stability augmentation system) and to provide reference information for a tie-breaking condition at which an ILM(in-line monitor) cannot distinguish the faulty channel between two operating ones, the Kalman filter approach is investigated.

• Journal of Biosystems Engineering
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• v.22 no.2
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• pp.177-188
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• 1997

A pepper harvester using a pair of counter rotating helically wound cylinders as a pepper removal mechanism has been developed. Pepper harvesting by machines under the customary cultivation practice was expected to lower land productivity, that most farmers were concerned about. As one way to compensate for loss in land productivity by machine harvest, experts on pepper cultivation suggested change of both varieties and plant density per area. From the view of machine design, their suggestion implied that distance between rows should be narrower and height of the pepper removal mechanism could be shorter. Experiments to improve perfect pepper recovery ratio and to reduce size of the pepper removal mechanism was accomplished. In order to be a economically feasible harvester, minimum pepper recovery ratio was required to be greater or equal to 80%. The research goal was achieved by both reducing the diameter of the wire-helices from 30 cm to 18 cm and increasing rotational speed of the wire-helices up to 425 rpm. The best perfect pepper recovery ratio was 82.3%. Validity of experiment design and interpretation on statistical analysis were discussed. To understand the pepper removal mechanism properly, a pepper removal theory based physics was judged to be necessary.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.10
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• pp.130-136
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• 2008

The purpose of this study was to investigate chaotic characteristics of major joint motions during treadmill walking. Gait experiments were carried out for 20 healthy young women. The subjects were asked to walk on a treadmill at their own natural speeds. The chaos analysis was used to quantify nonlinear motions of eleven major joints of each woman. The joints analyzed included the neck and the right and left shoulders, elbows, hips, knees and ankles. The recorded gait patterns were digitized and then coordinated by motion analysis software. Lyapunov exponent for every joint was calculated to evaluate joint characteristics from a state space created by time series and its embedding dimension. This study shows that differences in joint motion were statistically significant.

• Journal of the Korea Concrete Institute
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• v.13 no.4
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• pp.346-353
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• 2001

This research investigates the mixture proportioning of waste newsprint paper fiber for thin-cement product. Waste newsprint paper fibers obtained through shredded mechanically by a dry process. Waste newsprint paper fiber reinforced cement composites was manufacted by slurry-dewatering method. The waste newsprint paper fiber reinforcement conditions (fiber mass fraction, level of substitution of virgin fibers, level of fiber beating) and processing variables (pressed, unpressed) are optimized through experimental studies and statistical analyses based on factorial design of experiments and analyses of variance. The optimized recycled waste newsprint paper fiber reinforced cement composites were technically evaluated. The results are shown to possess acceptable properties and strong potentials of the recycling of waste newsprint paper of the reinforcement of thin-cement products.

• The Korean Journal of Applied Statistics
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• v.32 no.6
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• pp.867-878
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• 2019

In this paper, we applied modified slope rotatability introduced by Victorbabu (2005) to the central composite design of second type, and studied related content. We suggested methods of constructing central composite designs of second type which have modified slope rotatability. Especially, this property has the advantage that it can be used to sequential experiments, because we can obtain central composite designs of second type which have modified slope rotatability by adding experimental points without changing the axial values to central composite designs of second type having Box-Hunter rotatability. We explained central composite designs of second type which have modified slope rotatability by using two examples.

• Advances in Computational Design
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• v.5 no.2
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• pp.195-207
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• 2020

The present study focuses on the application of artificial neural network (ANN) and Multiple linear Regression (MLR) analysis for developing a model to predict the unconfined compressive strength (UCS) and split tensile strength (STS) of the fiber reinforced clay stabilized with grass ash, fly ash and lime. Unconfined compressive strength and Split tensile strength are the nonlinear functions and becomes difficult for developing a predicting model. Artificial neural networks are the efficient tools for predicting models possessing non linearity and are used in the present study along with regression analysis for predicting both UCS and STS. The data required for the model was obtained by systematic experiments performed on only Kaolin clay, clay mixed with varying percentages of fly ash, grass ash, polypropylene fibers and lime as between 10-20%, 1-4%, 0-1.5% and 0-8% respectively. Further, the optimum values of the various stabilizing materials were determined from the experiments. The effect of stabilization is observed by performing compaction tests, split tensile tests and unconfined compression tests. ANN models are trained using the inputs and targets obtained from the experiments. Performance of ANN and Regression analysis is checked with statistical error of correlation coefficient (R) and both the methods predict the UCS and STS values quite well; but it is observed that ANN can predict both the values of UCS as well as STS simultaneously whereas MLR predicts the values separately. It is also observed that only STS values can be predicted efficiently by MLR.

• Korean Chemical Engineering Research
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• v.56 no.4
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• pp.568-576
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• 2018

In order to investigate the adsorption characteristics of the antibiotics trimethoprim (TMP) by activated carbon (WCAC) prepared from waste citrus peel, the effects of operating parameters on the TMP adsorption were investigated by using a response surface methodology (RSM). Batch experiments were carried out according to a four-factor Box-Behnken experimental design with four input parameters : concentration ($X_1$: 50-150 mg/L), pH ($X_2$: 4-10), temperature ($X_3$: 293-323 K), adsorbent dose ($X_4$: 0.05-0.15 g). The experimental data were fitted to a second-order polynomial equation by the multiple regression analysis and examined using statistical methods. The significance of the independent variables and their interactions was assessed by ANOVA and t-test statistical techniques. Statistical results showed that concentration of TMP was the most effective parameter in comparison with others. The adsorption process can be well described by the pseudo-second order kinetic model. The experimental data of isotherm followed the Langmuir isotherm model. The maximum adsorption amount of TMP by WCAC calculated from the Langmuir isotherm model was 144.9 mg/g at 293 K.

• Journal of the Korean GEO-environmental Society
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• v.13 no.6
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• pp.51-57
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• 2012

This study investigated on the photolytic degradation of Triclosan by E-beam process. The optimization of process was investigated during a series of batch experiments by design of experiments(DOEs). The DOE was one of the statistical application that was used for designed the response surface to determine the effects of each parameters. The responses were applied as removal rate of Triclosan(%, $Y_1$) and TOC removal rate(%, $Y_2$). Two independent variables were concentration of Triclosan and irradiation intensity that were designed as "$x_1$" and irradiation intensity was designed as "$x_2$". The regression equation in coded parameter between the Triclosan removal efficiencies(%) and TOC removal efficiencies(%) was $Y_1=63-12.4335x_1+15.1835x_2+5.8125x{_1}^2-5.6875x{_2}^2-0.75x_1x_2(R^2=95.1%,\;R^2(Adj)=91.7%)$ and $Y_2=46-8.8462x_1+11.7175x_2-0.75x{_1}^2-6.25x{_2}^2(R^2=98.7%,\;R^2(Adj)=97.7%)$, respectively. The model predictions agreed well with the experimentally observed results $R^2$ and $R^2(Adj)$ over 90% within both of $Y_1$ and $Y_2$. This result shows that the regression model express well about the effects of parameters on E-beam process and the statistical method was successfully applied.

• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.529-535
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• 1998

This study was made to investigate the effect of variation in pulping process conditions such as wastepaper blending treatments, temperature, and chemical blending treatments on the deinked pulp. Design of experiments was used to select the major factors which significantly influenced on the deinked pulp. As one of the statistical analysis technique, analysis of variance and multiple comparison technique was used to find the best process condition and the predicted values and confidence intervals for brightness and strength were obtained. In the condition of $Na_2SiO_3$ 2.0%, $H_2O_2$ 0.5% and wastepaper blending treatments (KONP : AONP : OMG = 40 : 30 : 30 wt %) the highest brightness of 50.5% was predicted with 90% confidence interval (49.0, 52.0). On a concentration of $H_2O_2$ 0.5%, the highest tensile index of $35.7N{\cdot}m/g$ was predicted with 90% confidence interval (34.6, 36.6) at the pulping temperature of $50^{\circ}C$. On a concentration of surfactant 0.1%, the highest burst index of $0.129kPa{\cdot}m^2/g$ was predicted with 90% confidence interval (0.125, 0.133) at the pulping temperature of $50^{\circ}C$.