• Journal of the Korean Data and Information Science Society
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• v.11 no.1
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• pp.65-72
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• 2000

Robust design is an approach to reducing performance variation of quality characteristic values in quality engineering. Taguchi parameter design has a great deal of advantages but it also has some disadvantages. The various research efforts aimed at developing alternative methods. In the Taguchi parameter design, the product-array approach using orthogonal arrays is mainly used. However, it often requires an excessive number of experiments. An alternative approach, which is called the combined-array approach, was suggested by Welch et. al. (1990) and studied by others. In this paper we make a comparative study on optimization procedures to robust design in the two different experimental design(product array, combined array) approaches the Mough the Monte Carlo simulation.

• Biomolecules & Therapeutics
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• v.8 no.1
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• pp.63-72
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• 2000

We intended to show some basic requirements for spectrum analysis of electroencephalogram (EEG) by visualizing the differences of the results according to different values of some parameters for analysis. Spectrum analysis is the most popular technique applied for the quantitative analysis of the electroen- cephalographic signals. Each step from signal acquisition through spectrum analysis to presentation of parameters was examined with providing some different values of parameters. The steps are:(1) signal acquisition; (2) spectrum analysis; (3) parameter extractions; and (4) presentation of results. In the step of signal acquisition, filtering and amplification of signal should be considered and sampling rate for analog-to-digital conversion is two-time faster than highest frequency component of signal. For the spectrum analysis, the length of signal or epoch size transformed to a function on frequency domain by courier transform is important. Win dowing method applied for the pre-processing before the analysis should be considered for reducing leakage problem. In the step of parameter extraction, data reduction has to be considered so that statistical comparison can be used in appropriate number of parameters. Generally, the log of power of all bands is derived from the spectrum. For good visualization and quantitative evaluation of time course of the parameters are presented in chronospectrogram.

• Management Science and Financial Engineering
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• v.12 no.2
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• pp.87-110
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• 2006

In a hierarchical road network, all roads can be classified according to their attributes such as speed limit, number of lanes, etc. By splitting the whole road network into the subnetworks of the highlevel and low-level roads, we can reduce the size of the network to be calculated at once, and find a path in the way that drivers usually adopt when searching out a travel route. To exploit the hierarchical property of road networks, we define a convenient path and propose an algorithm for finding convenient paths. We introduce a parameter indicating the driver's tolerance to the difference between the length of a convenient path and that of a shortest convenient path. From this parameter, we can determine how far we have to search for the entering and exiting gateway. We also propose some techniques for reducing the number of pairs of entries and exits to be searched in a road network. A result of the computational experiment on a real road network is given to show the efficiency of the proposed algorithm.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.3
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• pp.163-172
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• 1993

A probabilistic approach for evaluation of prediction of the strains using Lade's single surface constitutive model was employed, based on first-order approximate mean and variance. Several experiments such as isotropic compression and drained triaxial compression tests were conducted to examine the variabilities of soil parameters for Lade's model. By taking into account the results of the experimental data such as mean values and standard deviations of soil parameter's, a new probabilistic approach, which explains the uncertainty of computed strains, is applied. The magnitude of the COV for each parameter and the correlation coefficient between the two parameters can be effectively used for reducing the number of the parameters for the model. It is concluded that Lade's single surface constitutive model is surperior model for the prediction of the strain, because the COV of strains is under the "0.51".

• Korean Journal of Remote Sensing
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• v.34 no.1
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• pp.141-150
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• 2018

Crop type classification is essential for supporting agricultural decisions and resource monitoring. Remote sensing techniques, especially using hyperspectral imagery, have been effective in agricultural applications. Hyperspectral imagery acquires contiguous and narrow spectral bands in a wide range. However, large dimensionality results in unreliable estimates of classifiers and high computational burdens. Therefore, reducing the dimensionality of hyperspectral imagery is necessary. In this study, the Random Forest (RF) classifier was utilized for dimensionality reduction as well as classification purpose. RF is an ensemble-learning algorithm created based on the Classification and Regression Tree (CART), which has gained attention due to its high classification accuracy and fast processing speed. The RF performance for crop classification with airborne hyperspectral imagery was assessed. The study area was the cultivated area in Chogye-myeon, Habcheon-gun, Gyeongsangnam-do, South Korea, where the main crops are garlic, onion, and wheat. Parameter optimization was conducted to maximize the classification accuracy. Then, the dimensionality reduction was conducted based on RF variable importance. The result shows that using the selected bands presents an excellent classification accuracy without using whole datasets. Moreover, a majority of selected bands are concentrated on visible (VIS) region, especially region related to chlorophyll content. Therefore, it can be inferred that the phenological status after the mature stage influences red-edge spectral reflectance.

• Wind and Structures
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• v.2 no.3
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• pp.151-171
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• 1999

In its 90 years of life, the Tuned Mass Damper have found application in many fields of engineering as a vibration reducing device. The evolution of the theory of TMDs is briefly outlined in the paper. A generalised mathematical linear model for the analysis of the response of line-like structures with TMDs is presented. The system matrices of the system including the TMDs are written in the state space as a function of the mean wind speed. The stability of the system can be analysed and the Power Spectral Density Function of any response parameter calculated, taking into account an arbitrary number of modes of vibration as well as an arbitrary number of TMDs, for any given PSDF of the excitation. The procedure can be used to optimise the number, position and mechanical properties of the damping devices, with respect to any response parameter. Due to the stationarity of the excitation, the method is well suited to structures subjected to the wind action. In particular the procedure allows the calculation of the onset galloping wind speed and the response to buffeting, and a linearisation of the aeroelastic behaviour allows its use also for the evaluation of the response to vortex shedding. Finally three examples illustrate the suggested procedure.

• Food Science and Preservation
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• v.31 no.3
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• pp.499-505
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• 2024

Patulin has been reported as a risk factor in various foods, especially apple juice. This study monitored residual patulin and polyphenolic content in apple juice during post-irradiation storage conditions. Response surface methodology (RSM) was applied to monitor the changes in dependent variables (Yn, patulin, and polyphenolics) as affected by independent variables, such as storage temperature (Xi, -20℃ to 20℃), irradiation dose (Xii, 0-2 kGy), and storage period (Xiii, 0-20 days), which were based on a central composite design. The predicted peak point resulted in the lowest residual patulin content of 58.42 ppb with the corresponding independent parameter conditions, such as 18.19℃ of storage temperature, 1.24 kGy of irradiation dose, and 13.42 days of storage period. The residual patulin content of 58.42 ppb is the minimum desirable level, representing a 91% reduction compared to the non-irradiated control (675.00 ppb). A maximum polyphenolics content (11.98 mg/g) was obtained under the predicted maximum conditions of 14.40℃, 0.78 kGy, and 3.4 days. The most influential parameter in reducing residual patulin content while maintaining polyphenolic content in apple juice was irradiation dose (p<0.01), which showed potential to be applied in controlling the patulin levels in apple juice.

• The KIPS Transactions:PartC
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• v.13C no.5 s.108
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• pp.559-566
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• 2006

Virus throttling technique, one of many early worm detection techniques, detects the Internet worm propagation by limiting the connect requests within a certain ratio. The typical virus throttling detects worm occurrence by monitoring the length of delay queue with the fixed period of rate limiter. In this paper, we propose an algorithm that controls the period of rate limiter autonomically by utilizing the weighted average delay queue length and suggest various period determination policies that use the weighted average delay queue length as an input parameter. Through deep experiments, it is verified that the proposed technique is able to lessen inconvenience of users by reducing the connection delay time with haying just little effect on worm detection time.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.1110-1116
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• 1993

A study on optimum operation performances of power efficiency, economy and exhaust emissions for a tractor was conducted. A mathematical model of multiple degree polynomial equation was applied to established the function of solid multiple parameter curves for specific fuel consumption (ge), cabon monoxide (CO) ,hydrcarbons (HC) and cabonaceous smoke (Rb). The optimum operation theorems for economy operation indicated by ge and for exhaust emissions described by Co , HC and Rb were obtained from analytical method and performance test data. The optimum operation theorems could exhibit optimum operation working points, curves, and regions. The optimum matching relations of engine speed and transmission parameters were analyzed by using computer simulation methods in accordance with the tractor specifications , actual farm working conditions in a typical drawbar pull work such as plowing , the optimum operation objective function, the ideal transmission ratio, practical gear shif ing positions and practical travel speed of the tractor TN55 medel. The results of the anlayzes indicated clearly that the optimum power efficient operation, energy saving and pollution reducing would be realized if the tractor would be operated according to theoptimum operation methods.

• Journal of the Korean Magnetic Resonance Society
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• v.21 no.4
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• pp.139-144
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• 2017

Ni(II) containing coenzyme F430 catalyzes the reduction of $CO_2$ in methanogen. Macrocyclic Ni(II) complexes with N,O shiff bases have been received a great attention since metal ions play an important role in the catalysis of reduction. The reducing power of metal complexes are supposed to be dependent on oxidoreduction state of metal ion and structural properties of macrocyclic ring moiety that can enhance electrochemical properties in catalytic process. Six different ${\alpha}$-oximinoketone compounds, precursor of macrocyclic ligands used in $CO_2$ reduction coenzyme F430 model complexes, were synthesized with yields over 90% and characterized by NMR. The molecular geometries of ${\alpha}$-oximinoketone analogues were fully optimized at Beck's-three-parameter hybrid (B3LYP) method in density functional theory (DFT) method with $6-31+G^*$ basis set using the ab initio program. In order to understand molecular planarity and substitutional effects that may enhance reducing power of metal ion are studied by computing the structure-dependent $^{13}C$-NMR chemical shift and comparing with experimental results.