• Smart Structures and Systems
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• v.26 no.3
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• pp.345-360
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• 2020

Modern swarm intelligence heuristic search methods are widely applied in the field of structural health monitoring due to their advantages of excellent global search capacity, loose requirement of initial guess and ease of computational implementation etc. To this end, a hybrid strategy is proposed based on butterfly optimization algorithm (BOA) and differential evolution (DE) with purpose of effective combination of their merits. In the proposed identification strategy, two improvements including mutation and crossover operations of DE, and dynamic adaptive operators are introduced into original BOA to reduce the risk to be trapped in local optimum and increase global search capability. The performance of the proposed algorithm, hybrid butterfly optimization and differential evolution algorithm (HBODEA) is evaluated by two numerical examples of a simply supported beam and a 37-bar truss structure, as well as an experimental test of 8-story shear-type steel frame structure in the laboratory. Compared with BOA and DE, the numerical and experimental results show that the proposed HBODEA is more robust to detect the reduction of stiffness with limited sensors and contaminated measurements. In addition, the effect of search space, two dynamic operators, population size on identification accuracy and efficiency of the proposed identification strategy are further investigated.

• 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 $38.6^{\circ}C$.

• Journal of Radiation Protection and Research
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• v.33 no.1
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• pp.27-34
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• 2008

A Korean urban contamination model METRO-K (${\underline{M}}odel$ for ${\underline{E}}stimates$ the ${\underline{T}}ransient$ Behavior of ${\underline{R}}adi{\underline{O}}active$ Materials in the ${\underline{K}}orean$ Urban Environment, which is capable of calculating the exposure doses resulting from radioactive contamination in an urban environment, is taking part in a model testing program EMRAS (${\underline{E}}nvironmental$ ${\underline{M}}odelling$ for ${\underline{RA}}diation$ ${\underline{S}}afety$) oragnized by the IAEA (${\underline{I}}nternational$ ${\underline{A}}tomic$ ${\underline{E}}nergy$ ${\underline{A}}gency$). For radioactive contamination scenarios of Pripyat districts and a hypothetical RDD (${\underline{R}}adiological$ ${\underline{D}}ispersal$ ${\underline{D}}evice$), the predicted results using METRO-K were submitted to the EMRAS's Urban Contamination Working Group. In this paper, the predicted results for the contamination scenarios of a Pripyat district were shown in case of both without remediation measures and with ones. Comparing with the predictied results of the models that have taken part in EMRAS program, a feasibility for decision-making support of METRO-K was investigated. As a predicted result of METRO-K, to take immediately remediation measures following a radioactive contamination, if possible, might be one of the best ways to reduce exposure dose. It was found that the discrepancies of predicted results among the models are resulted from 1) modeling approaches and applied parameter values, 2) exposure pathways which are considered in models, 3) assumptions of assessor such as contamination surfaces which might affect to an exposure receptor and their sizes, 4) parameter values which are related with remediation measures applied through literature survey. It was indentified that a Korean urban contamination model METRO-K is a useful tool for dicision-making support through the participation of EMRAS program.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.1
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• pp.53-60
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• 2021

High voltage CV cables have been widely installed underground due to their convenience and urban aesthetics. However, cable accidents have occurred frequently owing to poor construction and natural degradations. This paper proposes the method to measure the multi parameter measurement for optimum diagnostics of high voltage cable connection parts and verifies its technical usefulness. This measurement is intended to diagnose degradations of cable connection parts by using simultaneous vibration and thermography as well as partial discharge(PD). The experiment in a shielded laboratory was carried out to verify the usefulness of the multi parameter measurement. The experiment defined the degradation of the cable connection part as 12 types, and produced each degradation sample. As a result of experiment, it was possible to check the correlation of vibration signals with regard to progress in some defects. In the case of thermography, the coherence with regard to the progress of some defects was found. We figure that the proposed method would be useful also in the noise environment.

• Korean Journal of Human Ecology
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• v.14 no.5
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• pp.821-832
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• 2005

The purpose of this study is to investigate bathing habits and behaviors, and to find out consumers' needs for washcloth, which in this case refers to Korean exfoliating cloth for bathing purpose. Subjects of this study were females of 20s to 50s living in urban area. Four hundred and twenty-six (426) women were interviewed with a structured questionnaire. Data were analyzed by ANOVA, factor analysis, correlation analysis, MDS. The results of this study are briefly summarized as follows: The most popular bathing type was shower (84.9%). Personal hygiene was one of the commonest purpose of bathing, and other purposes included health maintenance, stress alleviation, and beauty in order. Dimensions of consumer needs for washcloth were extracted from factor analysis as following properties: tactile, tough, aesthetic, constructive, and hygienic. The preference for washcloth type was related to skin type. "Non-skin damage property" was the most important parameter to choose washcloth and the other parameters included massage effect, tactile property, foaming property, and easy-to-use property.

• Journal of Environmental Science International
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• v.16 no.5
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• pp.561-569
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• 2007

This study used SCS-CN method to estimate the real recharge of the study area which is one of the most reasonable techniques to estimate groundwater recharge when there is no available runoff data in a watershed. From the results of tile real recharge analysis for the study area using SCS-CN method, it was analyzed that the year 1994 when the drought was severe shotted the lowest recharge of 106.3mm with recharge rate of 12.4%, and the highest recharge of 285.6mm with recharge rate of 21.8% occurred in 1990. Yearly average recharge of 213.2mm was obtained, and tile average recharge rate was 16.9%/year. KOG-FLOW model which has powerful post process functions consists of setting environments for input parameters in Korean language, and help function is added to each input data. Detailed information for each parameter is displayed when the icon is placed on the input parameters, and geologic boundaries or initial head data for each layer can be set easily on work sheet. The relative errors (R. E.) for each model's observed values and calculated values are $0.156{\sim}0.432$ in case of KOG-FLOW, and $0.451{\sim}1.175$ in case of WINFLOW, therefore it is known that KOG-FLOW model developed in this study produced results compared to observed head values.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.6
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• pp.33-42
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• 2010

Travel speed is an important parameter in measurement of road traffic. UTIS(Urban Traffic Information System) was developed as a type of section detector. However, UTIS incur errors caused by irregular vehicle trajectories, wireless communication range and so on. This paper suggests a new model that use an error-filtering algorithm to improve the accuracy of travel speed measurements. In the field test, the variance of the percent errors measured by the new model was reduced. Therefore, it can be concluded that the proposed model significantly improves travel speed measuring accuracy.

• Journal of Korean Society of Disaster and Security
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• v.10 no.1
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• pp.35-42
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• 2017

This is a comparative study on the characteristics of excavated soils, which is proceeded using soil strength parameter by literature, geotechnical investigation, standard penetration test by drilling, and downhole test by borehole at six sites in urban areas. The results of these site surveys are used as basic data for the evaluation and development of prediction of ground subsidence risk. Geotechnical properties are estimated with the result of standard penetration test-N value and literature. The dynamic geotechnical characteristics are also estimated with top-down seismic exploration at borehole.

• The KSFM Journal of Fluid Machinery
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• v.18 no.3
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• pp.60-65
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• 2015

This paper deals with performance characteristics and efficiencies of Pelton turbine can be applied as one of ERDs (Energy Recovery Devices) of PRO (Pressure Retarded Osmosis) system for desalination. The objective of this study is experimentally estimating the performance of micro-scale Pelton turbine for PRO pilot plant. Especially the performance characteristics with variations of jet nozzle diameter of Pelton turbine are discussed in detail. In order to do this, lab scale test rig of Pelton turbine was made for performance test, which includes water tank, Pelton wheel with buckets, jet nozzle and torque brake and so on. The parameter effects related on Pelton turbine's efficiency were investigated and discussed on the influence of the variations of load and speed ratio.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.6
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• pp.63-73
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• 2011

Travel speed is an important parameter for measuring road traffic. UTIS(Urban Traffic Information System) was developed as a mobile detector for measuring link travel speeds in South Korea. After investigation, we founded that UTIS includes some missing data caused by the lack of probe vehicles on road segments, system failures and etc. Imputation is the practice of filling in missing data with estimated values. In this paper, we suggests a new model for imputing missing data to provide accurate link travel speeds to the public. In the field test, new model showed the travel speed measuring accuracy of 93.6%. Therefore, it can be concluded that the proposed model significantly improves travel speed measuring accuracy.