• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.5
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• pp.92-103
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• 2015

Box-Wilson experimental design method, known as central composite design, is the design of any information-gathering exercises where variation is present. This method was devised to gather as much data as possible in spite of the low design cost. This method was employed to model the effect of mixing factors on several performances of 60 MPa high strength self compacting concrete and to numerically calculate the optimal mix proportion. The nonlinear relations between factors and responses of HSSCC were approximated in the form of second order polynomial equation. In order to characterize five performances like compressive strength, passing ability, segregation resistance, manufacturing cost and density depending on five factors like water-binder ratio, cement content, fine aggregate percentage, fly ash content and superplasticizer content, the experiments were made at the total 52 experimental points composed of 32 factorial points, 10 axial points and 10 center points. The study results showed that Box-Wilson experimental design was really effective in designing the experiments and analyzing the relation between factor and response.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.2
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• pp.131-135
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• 2007

This study was performed as an effort to reduce soil loss by investigating the phase of water flow according to soil texture and rainfall pattern and by determining the canopy cover subfactor in the RUSLE (revised universal soil loss equation). Red pepper was planted at the 15% sloped lysimeter of $2m{\times}5m{\times}0.5m$ ($width{\times}length{\times}depth$) with three different textured soils (loam, clay loam and sandy loam) and the relationship between amount and intensity of rainfall; soil loss and the amount of runoff; and amount of rainfall and runoff at different soil texture were measured at the experiment station of the National Institute of Agricultural Science and Technology (NIAST) during May to October of 2005. The amount of runoff increased with increasing amount of rainfall, showing difference in the relative increase rate of runoff at different soil texture. The increase rate of runoff with unit increase of rainfall for the lysimeter with red pepper was 0.44, 0.41 and 0.13 for loam, clayey loam and sandy loam, respectively. The minimum amount of rainfall for runoff was 23.53 mm for sandy loam, 10.35 mm for loam and 5.46 mm for clayey loam, respectively. The canopy cover subfactors of red pepper were 0.425, 0.459, and 0.478 for sandy loam, loam and clayey loam, respectively.

• Applied Chemistry for Engineering
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• v.29 no.6
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• pp.682-689
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• 2018

In this paper, the stability criteria of cosmeceuticals emulsion containing Broussonetia kazinoki extracts was established using the central composite design model. As optimization conditions of the emulsification using the central composite design model, concentrations of the emulsifier and emulsion stabilizer were used as a quantitative factor while emulsion stability index (ESI) and polydispersity index (PDI) were used as a reaction value. The targeted values of ESI and PDI were estimated as over 60% and the minimum number, respectively. Optimized concentrations of the emulsifier and emulsion stabilizer were 3.73 and 3.07 wt%, respectively, from the emulsification optimization based on ESI and PDI values. The estimated reaction values of ESI and PDI were 60% and 0.585, respectively. As concentrations of the emulsifier and emulsion stabilizer increased, the stability of the emulsion prepared tended to increase. The emulsifier was one of the most influential factors for ESI than the emulsion stabilizer. On the other hand, the PDI value was similarly affected by both the emulsion and emulsion stabilizer. The ESI of the cosmeceuticals emulsion prepared under experimental conditions deduced from the central synthesis planning model showed at least about 45% of the stability. However, all of the emulsions were separated after 4 weeks from the initial preparation. When the concentration of the emulsifier was more than 3.72 wt%, the ESI value was over 60%. Also the layer separation rate decreased with increasing the emulsion stabilizer concentration.

• Journal of Drive and Control
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• v.13 no.4
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• pp.59-67
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• 2016

This paper proposes a model-prediction-based collision-avoidance algorithm for excavators for which the recursive-least-squares (RLS) estimation of the excavator's rotational inertia is used. To estimate the rotational inertia of the excavator, the RLS estimation with multiple forgetting and two updating rules for the nominal parameter and the forgetting factors was conducted based on the excavator-swing dynamics. The average value of the estimated rotational inertia that is for the minimizing effects of the estimation error was computed using the recursive-average method with forgetting. Based on the swing dynamics, the computed average of the rotational inertia, the damping coefficient for braking, and the excavator's braking angle were predicted, and the predicted braking angle was compared with the detected-object angle for a safety evaluation. The safety level defined in this study consists of the three levels safe, warning, and emergency braking. The analytical rotational-inertia-based performance evaluation of the designed estimation algorithm was conducted using a typical working scenario. The results of the safety evaluation show that the predictive safety-evaluation algorithm of the proposed model can evaluate the safety level of the excavator during its operation.

• Food Science and Preservation
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• v.17 no.1
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• pp.84-90
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• 2010

We investigated methods to minimize patulin content during processing of apple juice in Korea. Ascorbic acid concentration (100, 200, 300, and 400 ppm) and activated carbon concentration (50, 100, 150, and 200 ppm) were the parameters assessed by response surface methodology. Residual patulin was lowest in the presence of 237.77 ppm ascorbic acid and 106.58 ppm activated carbon, and increased as these levels increased. Sugar content was affected more byascorbic acid concentration than by activated carbon level, and the total phenol content was revealed to be the saddle point. In addition, the expected total flavonoid content was maximized with increased levels of ascorbic acid and activated carbon. The data showed that 246-274 ppm (v/v) ascorbic acid and 93-122 ppm (v/v) activated carbon were optimal for juice extraction, and the $R^2$ quality factor for juice processing was significant and within the range of 1-10% for all tested parameters.

• Journal of Drive and Control
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• v.14 no.2
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• pp.16-22
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• 2017

This paper presents the algorithm of an adaptive model-free-control-based steering control for multi-axle all-terrain cranes for which the recursive least squares with forgetting are applied. To optimally control the actual system in the real world, the linear or nonlinear mathematical model of the system should be given for the determination of the optimal control inputs; however, it is difficult to derive the mathematical model due to the actual system's complexity and nonlinearity. To address this problem, the proposed adaptive model-free controller is used to control the steering angle of a multi-axle crane. The proposed model-free control algorithm uses only the input and output signals of the system to determine the optimal inputs. The recursive least-squares algorithm identifies first-order systems. The uncertainty between the identified system and the actual system was estimated based on the disturbance observer. The proposed control algorithm was used for the steering control of a multi-axle crane, where only the steering input and the desired yaw rate were employed, to track the reference path. The controller and performance evaluations were constructed and conducted in the Matlab/Simulink environment. The evaluation results show that the proposed adaptive model-free-control-based steering-control algorithm produces a sound path-tracking performance.

• Journal of Soil and Groundwater Environment
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• v.7 no.4
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• pp.17-23
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• 2002

Pumping tests were carried out from seven wells in fractured rocks. The time-drawdown data were obtained from pumping wells and corrected for the elapsed time of step drawdown test using Cooper-Jacob's method. A statistical method. the least square of error, was used to yield the coefficient of aquifer losses, the coefficient of well losses, and the power which indicates the severity of the turbulence. The values of the power range from 1.65 to 6.48. The well losses result mainly from turbulent flow caused by radial flow nearby pumping wells. The turbulent flow depends on Reynolds number. Since the hydraulic characteristics of fractured rocks control the fluid velocity, the value of the power is an important factor to understand the aquifer system of fractured rocks.

• Journal of Korean Society of Steel Construction
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• v.14 no.5 s.60
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• pp.603-612
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• 2002

Numerical analyses have been carried out in order to check the applicability of high-strength steel to a medium-sized steel bridge. Using the yield strength of steel, Average Daily Truck Traffic (ADTT), and fatigue grade of structural detail as analytical parameters, the minimum weight sections that satisfy the limit states of the AASHTO LRFD design specification were determined through an optimization scheme. Likewise, the effects of the number of girders and span length on the applicability of high-strength steel were evaluated. Results show that high-strength steel may be employed in the steel bridge, since steel weight decreases with increasing yield strength regardless of the fatigue effect. Nonetheless, appropriate countermeasures against fatigue should be determined since it is a major factor in the effective use of high-strength steel in steel bridges.

• Korean Journal of Head & Neck Oncology
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• v.25 no.1
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• pp.8-11
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• 2009

Background and Objectives : In the TNM 6th classification system, extrathyroidal invasion of differentiated thyroid carcinoma has been classified into T3(minimal invasion), T4a(extended invasion), and T4b(more extensive unresectable invasion) according to the degree and it has been recognized as an important prognostic factor. In this study, we investigated the prognostic significances of minimal extrathyroidal invasion in papillary thyroid carcinoma(PTC). Material and Methods : We retrospectively studied 221 patients who are underwent thyroidectomy due to PTC from September 2003 to December 2006. Fifty-four(24.4%) patients had a PTC with minimal extrathyroidal invasion(Group A) and 167(75.6%) patients had a PTC without extrathyroidal invasion(Group B). The existence of minimal extrathyroidal invasion was based on operative and pathological findings. Results : Minimal extrathyroidal invasion in PTC was related to tumor size, lymph node metastasis, and operative method(p<0.001). But, there is no significant difference in age, gender, and multifocality between Group A and B. Hashimoto's thyroiditis was observed more frequently in Group B(p=0.019). Conclusion : These findings suggest that minimal extrathyroidal invasion is related to poor prognostic factors in PTC. Therefore, aggressive surgical approach is required when there is evidence of minimal extrathyroidal invasion in preoperative radiologic examination or operative finding.

• Journal of the Society of Naval Architects of Korea
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• v.28 no.1
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• pp.125-138
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• 1991

In this paper, an efficient method for the analysis of damage and strength of double bottom structure in stranding is described by using idealized structural unit method. Also a procedure for the determination of the effective double bottom height which is required in order to protect the inner-bottom plate is proposed. In the comparison between the present solution and he existing experimental and numerical results in stranding, its observed that the present method gives reasonable results requiring very shorts computiong times. The present method is then applied to the double bottom structure of 40K product oil carrier which is designed by the double skin design concept as an example. By performing the series of analysis, the influence of vertical member space, plate thickness and double bottom height on the energy absorption capacity of the double bottom structure in stranding is investigated. Also the minimum double bottom height with varying each design variable Is calculated based on the above result.