• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.6
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• pp.729-736
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• 2015

In this paper, It was performed to optimize for the deck's structural design of a double ended car ferry ship respect to Goal-Driven Optimization (GDO). It was examined for the strength and deformation of the deck and determined to save economic cost the optimal point. The deck thickness based on the Design of Experiments (DOE) and response surface method was increased to 110%. and can improve the deck's strength and stiffness. By performing the regression analysis respect to the result, we propose the optimal regression model formula as a third degree polynomial regression models. The coefficient of determination $R^2$ was about 0.98 and reliability could be obtained.

• Membrane and Water Treatment
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• v.10 no.6
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• pp.471-484
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• 2019

The complex combination of organic contaminants in the wastewater made water treatment challenging; hence, organic matter in water bodies is usually measured in terms of organic carbon. Since it is important to identify the types of compounds when deciding suitable treatment methods, this study implemented a quantitative and qualitative analysis of the organic matter content in an actual graywater sample from Ulsan, Republic of Korea using mass spectroscopy (MS). The graywater was treated using adsorption to remove the organic contaminants. Using orbitrap MS, the organic matter content between an untreated graywater and the treated effluent were compared which yielded a significant formula count difference for the samples. It was revealed that CHON formula has the highest removal count. Isotherm studies found that the Freundlich equation was the best fit with a coefficient of determination ($R^2$) of 0.9705 indicating a heterogenous GAC surface with a multilayer characteristic. Kinetics experiments fit the pseudo-second order equation with an $R^2$ of 0.9998 implying that chemisorption is the rate-determining step between the organic compounds and GAC at rate constant of $52.53g/mg{\cdot}h$. At low temperatures, the reaction between GAC and organic compounds were found to be spontaneous and exothermic. The conditions for optimization were set to achieve a maximum DOC and TN removal which yielded removal percentages of 94.59% and 80.75% for the DOC and TN, respectively. The optimum parameter values are the following: pH 6.3, 2.46 g of GAC for every 30 mL of graywater sample, 23.39 hrs contact time and $38.6^{\circ}C$.

• Steel and Composite Structures
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• v.51 no.4
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• pp.441-456
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• 2024

This paper aims to develop Machine Learning (ML) algorithms to predict the buckling resistance of cold-formed steel (CFS) channels with restrained flanges, widely used in typical CFS sheathed wall panels, and provide practical design tools for engineers. The effects of cross-sectional restraints were first evaluated on the elastic buckling behaviour of CFS channels subjected to pure axial compressive load or bending moment. Feedforward multi-layer Artificial Neural Networks (ANNs) were then trained on different datasets comprising CFS channels with various dimensions and properties, plate thicknesses, and restraining conditions on one or two flanges, while the elastic distortional buckling resistance of the elements were determined according to the Finite Strip Method (FSM). To develop less biased networks and ensure that every observation from the original dataset has the chance of appearing in the training and test set, a K-fold cross-validation technique was implemented. In addition, the hyperparameters of the ANNs were tuned using a grid search technique to provide ANNs with optimum performances. The results demonstrated that the trained ANNs were able to predict the elastic distortional buckling resistance of CFS flange-restrained elements with an average accuracy of 99% in terms of coefficient of determination. The developed models were then used to propose a simple ANN-based design formula for the prediction of the elastic distortional buckling stress of CFS flange-restrained elements. Finally, the proposed formula was further evaluated on a separate set of unseen data to ensure its accuracy for practical applications.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.10
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• pp.1430-1437
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• 2009

Functional bread was manufactured with single cell detritus (SCD) of sea tangle. The optimum ingredient formula for SCD bread was determined based on mixture model. Flour and water reduced max weight, strength, hardness and specific loaf volume, whereas the increased SCD reversed the volume change of dough. Flour increased $L^*$ and $b^*$ values of SCD bread, while SCD decreased. Flour and water decreased $a^*$ value, while SCD increased. Max weight, strength, hardness, specific loaf volume, $b^*$ value and water holding capacity (WHC) were linear model on ANOVA table, whereas distance, volume change of dough, $L^*$ and $a^*$ values were nonlinear model. The response constraint coefficient showed that SCD influenced texture of SCD bread more than flour and water did, whereas water influenced the volume change of dough, specific loaf volume and WHC more than flour and SCD did. Moreover, flour influenced color value more than did water and SCD. Distance and $a^*$ value fitted nonlinear model with interaction terms for flour-SCD and water-SCD. Optimum ingredient formula for SCD bread was: flour, 48.25%; water, 30.89%; SCD, 3.86%. Sensory evaluation of SCD bread was a little lower than industrial bread and electrolyzed SCD bread.

• Korean Journal of Environmental Agriculture
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• v.15 no.2
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• pp.232-238
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• 1996

This study was conducted to find out the optimum condition for $NH_4-N$ removal from wastewater by a zeolite column. The removal efficiency of $NH_4-N$ by a glass column packed with decreased with the increase in initial concentration, percolation velocity and fraction number. The result of multiple stepwise regressions, $NH_4-N$ removal efficiency by the zeolite column showed a high correlationship with various parameters such as percolation velocity, initial concentration, adsorption amount and fraction number. Theoretical formula by parameter coefficients of multiple stepwise regression was found to be $NH_4-N$ removal $efficiency=0.620{\times}amount$ of zeolite $-0.456{\times}percolation$ velocity $-0.212{\times}initial$ concentration $-3.038{\times}fraction$ number+100.1 In the case of the $NH_4-N$ removal efficiency in cattle farming wastewater, the experimental data were nearly coincident with the theoretical formula.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1C
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• pp.129-139
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• 2004

This paper studies the support region of an optimum (minimum mean-squre error) fixed-rate scalar quantizer for a Weibull source. The support region is defined to be the interval determined by the outermost thresholds of a quantizer and plays an important role in its performance, and hence it motivates this study. The paper reports the following specific results. First, approximation formulas are derived for the outermost thresholds of optimum scalar quantizers for a Weibull distributions. Second, in the case of Rayleigh and exponential distributions the derived approximation formulas are compared for the evaluation of their accuracy with the true values of optimum quantizers. Numerical results show that the formula for the leftmost threshold stays within 1% of the true value for 128 and 256 quantization points or more, for Rayleigh and exponential distribution, respectively, while that for the rightmost threshold does so for 512 and 32 quantization points or more. These formulas exhibit increased accuracy with the number of quantization points. In conclusion, the formulas have high accuracy. The contribution of the paper consists in the derivation of closed accurate formulas for the support of optimum.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.4
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• pp.383-399
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• 2020

Optimizing the spacing of the disc cutter is a key element in the design of the TBM cutter head, which determines the drilling performance of the TBM. The full-scale linear cutting test is known as the most reliable and accurate test for calculating the spacing of the disc cutter, but it has the disadvantage of costly and time-consuming for the full-scale experiment. In this study, through the numerical analysis study based on the discrete element method, the tendency between Specific Energy-S/P ratio according to uniaxial compression strength and penetration depth of rock was analyzed, and the optimum spacing of 17-inch disc cutter was derived. To examine the appropriateness of the numerical analysis model, the rolling force acting on the disc cutter was compared and reviewed with the CSM model. As a result of numerical analysis for the linear cutting test, the rolling force acting on the disc cutter was analyzed to be similar to the rolling force derived from the theoretical formula of the CSM model. From the numerical analysis on 5 UCS cases (50 MPa, 70 MPa, 100 MPa, 150 MPa, 200 MPa), it is found that the range of the optimum spacing of the disc cutter decreases as the rock strength increases. And it can be concluded that 80~100 mm of disc cutter spacing is the optimum range having minimum specific energy regardless of rock strength. This tends to coincide with the optimal spacing of previously reported disk cutters, which underpins the disk cutter spacing calculated through this study.

• Journal of the Korean Institute of Navigation
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• v.11 no.2
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• pp.1-31
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• 1987

Nowadays, the transportation of almost all cargoes depends on sea routes in international trade. In the transaction of trade, cargo transportation must be completed on the base of two contrary objectives, one of which is to protect the vessel, cargoes and crew aborad her safely through every step of the transportation and the other is to pursue profits from the transaction of the trade. In spite of the great development of the modern techniques in shipbuilding today, many sea disaters of big merchant vessels have been occurring successively in winter seasons every year on the sea routes of the North Pacific Ocean. Whenever the accident of losing a vessel in rough sea occurred , many experts of the country to which the vessel belonged had tried to take out the reason of the missing without manifesting the exact cause of the unhappy occurrence. In this paper, we calculated ocean wave status along the route of the North Pacific Ocean theoretically concluded by us as optimum on the basis of weather and sea conditions. In the calculation, we used ITTC wave spectrum formula and meteorological data of "Winds '||'&'||' Waves of the north Pacific Ocean" edited by Ship Research Institute of Japan on the basic data assembled by World Meterological Organization through past 10 years. We selected three sample vessels of most common size in the North Pacific Ocean Routes, a container, a log carrier and a bulk carrier and applied tree sample vessels to the calculated sea conditions for getting the rolling angles of the vessels and stress exerting on the hulls. Examining the calculated results, we concluded as follows; 1. Under the condition of these status7 by beaufort scale, "heave to" maneuvering is the best and safest way to steer every vessel. 2. The most dangerous part of sea area along the west bound optimum route of the North Pacific Ocean in winter season, is the southern sea area of the Kamchatka peninsula.a peninsula.

• Journal of the Korean Statistical Society
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• v.35 no.4
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• pp.377-395
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• 2006

In this paper we have suggested a family of chain estimators of the population mean $\bar{Y}$ of a study variate y using two auxiliary variates in two phase (double) sampling assuming that the coefficient of variation of the second auxiliary variable is known. It is well known that chain estimators are traditionally formulated when the population mean $\bar{X}_1$ of one of the two auxiliary variables, say $x_1$, is not known but the population mean $\bar{X}_2$ of the other auxiliary variate $x_2$ is available and $x_1$ has higher degree of positive correlation with the study variate y than $x_2$ has with y, $x_2$ being closely related to $x_1$. Here the classes are constructed when the population mean $\bar{X}_1\;of\;X_1$ is not known and the coefficient of variation $C_{x2}\;of\;X_2$ is known instead of population mean $\bar{X}_2$. Asymptotic expressions for the bias and mean square error (MSE) of the suggested family have been obtained. An asymptotic optimum estimator (AOE) is also identified with its MSE formula. The optimum sample sizes of the preliminary and final samples have been derived under a linear cost function. An empirical study has been carried out to show the superiority of the constructed estimator over others.

• Water for future
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• v.18 no.2
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• pp.175-185
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• 1985

This paper discusses the posibility of synthesizing flood hudrographs by the stroage function model. Eight small watersheds from Han, Gum, Nakdong, Youngsan river system were selected for this purpose. The optimum constants are computed from the chi square criterion by the SDFP methods Based on these constants, equations for the storage constant and Lag time are derived from the kinematic wave theory and storage function theory. These relations are examined by using optimum constants of the storage function model and assumptive constant of the kinematic wave model. Main results are sumarized as follows. 1. Constants of the storage function model are closely related to those of the kinematic wave model. The formula obtained theoretically is difficult to use practically because of the unclaified definition of factors. 2. In order to estimate constants of the storage function model for the practical purpose, new equations are also proposed for mountaneous area. 3. The verification of proposed equation is made for several recorded floods for mountaeous areas.