• Journal of Environmental Science International
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• v.25 no.5
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• pp.737-744
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• 2016

For electrolysis process using an insoluble electrode, electrochemical performance was greatly affected by the manufacturing method and procedure, such as the firing temperature, pre-treatment, type of precursor solution, coating method, electrode material, etc. Components of the electrode therein is one of the most important factors in electrochemical reaction. To achieve such characteristics, a appropriate ratio of the electrode material should be carefully chosen. The aim of this research was to apply experimental design method in the optimization of electrode component for the maximum generation of oxidants in electrochemical oxidation process. Mixture design, especially expanded simplex lattice design, in DOME (design of mixture experiments) with Design Expert - commercial software - was used to analyze the data. Analysis of variance (ANOVA) showed a high coefficient of determination ($R^2$) value of 0.9470, thus ensuring a satisfactory adjustment of the $3^{rd}$ order special cubic regression model with the experimental data. The application of response surface methodology (RSM) yielded the following regression equation, which is an empirical relationship between the TRO generation concentration and independent variables(mol ratio of 3 electrode components) in a real unit: TRO generation concentration $(mg/L)=TRO\;conc.=98.25{\times}[Ir]+49.71{\times}[Sn]+95.29{\times}[Sb]-16.91{\times}[Ir]{\times}[Sn]-29.47{\times}[Ir]{\times}[Sb]-22.65{\times}[Sn]{\times}[Sb]+703.19{\times}[Ir]{\times}[Sn]{\times}[Sb]$. The optimized formulation of the 3 component electrode for an high TRO (total residual oxidants) generation was acquired at mol ratio of Ir 0.406, Sn 0.210, Sb 0.384 (desirability d value, 1).

• Journal of Korean Society on Water Environment
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• v.34 no.6
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• pp.569-578
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• 2018

To minimize the negative alterations in hydrologic and water quality environment in urban areas due to urbanization, Low Impact Development (LID) techniques are actively applied. In Korea, LID facilities are classified as Non-point Pollution Reduction Facilities (NPRFs), and therefore they are evaluated using the performance evaluation method for NPRFs. However, while LID facilities are generally installed in small, distributed configuration and mainly work with the infiltration process, the existing NPRFs are installed on a large scale and mainly work with the reservoir process. Therefore, some limitations are expected in assessing both facilities using the same method as they differ in properties. To solve these problems, in this study, a new method for performance evaluation was proposed with focus on bio-retention LID facilities. EPA SWMM was used to reproduce the hydrologic and water quality phenomena in study area, and SWMM-LID module used to simulate TP interception performance by installing a bio-retention cell under various conditions through long-term simulations. Finally, an empirical formula for Load Capture Ratio (LCR) was derived based on storm water interception ratio in the same form as the existing method. Using the existing formula in estimating the LCR is likely to overestimate the performance of interception for non-point pollutants in the extremely low design capacity, and also underestimate it in the moderate and high design capacity.

• Journal of the Korea Convergence Society
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• v.11 no.12
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• pp.187-197
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• 2020

In this study, how international diversification of domestic companies increases corporate profits and increases the dividend income of paid-in capital investors, who provided the basis for corporate business activities in the process of distributing profits. I tried to find out if it had an effect. An empirical analysis was conducted using a fixed-effect model for companies with settlements at the end of December listed on the domestic securities market from 2011 to 2018. It was confirmed that the higher the level of international diversification of individual companies, the higher the company's dividend payout ratio and dividend yield. This means that companies can steadily expand corporate profits and dividend yield of shareholders by securing new overseas markets through international diversification, it can be seen that a company's international diversification strategy can contribute to the increase of corporate value by increasing the company's dividend payout ratio by increasing dividendable profit.

• Smart Structures and Systems
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• v.20 no.1
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• pp.61-74
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• 2017

One of the most reliable and simplest tools for structural vibration control in civil engineering is Tuned Mass Damper, TMD. Provided that the frequency and damping parameters of these dampers are tuned appropriately, they can reduce the vibrations of the structure through their generated inertia forces, as they vibrate continuously. To achieve the optimal parameters of TMD, many different methods have been provided so far. In old approaches, some formulas have been offered based on simplifying models and their applied loadings while novel procedures need to model structures completely in order to obtain TMD parameters. In this paper, with regard to the nonlinear decision-making of fuzzy systems and their enough ability to cope with different unreliability, a method is proposed. Furthermore, by taking advantage of both old and new methods a fuzzy system is designed to be operational and reduce uncertainties related to models and applied loads. To design fuzzy system, it is required to gain data on structures and optimum parameters of TMDs corresponding to these structures. This information is obtained through modeling MDOF systems with various numbers of stories subjected to far and near field earthquakes. The design of the fuzzy systems is performed by three methods: look-up table, the data space grid-partitioning, and clustering. After that, rule weights of Mamdani fuzzy system using the look-up table are optimized through genetic algorithm and rule weights of Sugeno fuzzy system designed based on grid-partitioning methods and clustering data are optimized through ANFIS (Adaptive Neuro-Fuzzy Inference System). By comparing these methods, it is observed that the fuzzy system technique based on data clustering has an efficient function to predict the optimal parameters of TMDs. In this method, average of errors in estimating frequency and damping ratio is close to zero. Also, standard deviation of frequency errors and damping ratio errors decrease by 78% and 4.1% respectively in comparison with the look-up table method. While, this reductions compared to the grid partitioning method are 2.2% and 1.8% respectively. In this research, TMD parameters are estimated for a 15-degree of freedom structure based on designed fuzzy system and are compared to parameters obtained from the genetic algorithm and empirical relations. The progress up to 1.9% and 2% under far-field earthquakes and 0.4% and 2.2% under near-field earthquakes is obtained in decreasing respectively roof maximum displacement and its RMS ratio through fuzzy system method compared to those obtained by empirical relations.

• Korean Business Review
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• v.19 no.1
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• pp.157-174
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• 2006

In the past, because Korean private venture capital firms could get government support and subsidies, they could be survived in the market without having required management capabilities, advanced venture investment techniques, and professional supporting agencies and institutions. However, business environments have changed a lot recently. Now, only through identifying the optimal financial structures(the ratio of debt to equity), Korean private venture capital firms can minimize investment risks and ensure higher profits. Since Modigliani and Miller(1958) criticized the existence of the optimal financial structure, there have been numerous studies on the optimal financial structure of firms. However, there is no empirical study investigating the financial structure of venture capital firms. The purpose of this article is to analyze the relationship between firm characteristics, financial security indies, and financial profit indices of korean private venture capital firms. We gathered the data from various sources, including the web pages and the financial statements for 2003 and 2004. By using the student's t-test and the correlation analysis, we showed that there are differences in the current ratio and the ratio of net profit to net sales between new and old korean private venture capital firms. Even though it is known that korean private venture capital firms does not have enough knowledge and investment technique to compete with global venture capital firms, our result show that old korean private venture capital firms have already built some knowledge and understanding of venture capital investing.

• The Journal of the Convergence on Culture Technology
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• v.4 no.1
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• pp.67-73
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• 2018

Financial plight condition firms difficulties accessing external funding, these firms will arrange scarce funds using tax avoidance can be a way of improvement of internal cash flow and internal funds securement. This study is empirical evidence presented the association between free cash flow can be represented for financial condition of firms and using tax avoidance for Kosdaq listed firms. Empirical analysis result, presented plus (+) results the association between free cash flow and tax avoidance. these results are in the previous year free cash flow is large firms purpose of internal cash holdings that increase of tax avoidance in order to minimize of cash outflow are based on tax burden. also interaction effect of free cash flow and debt ratio is presented influence of plus(+) on tax avoidance.

• International Area Studies Review
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• v.21 no.4
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• pp.85-100
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• 2017

The study tries to shed empirical light on the relation between the concentration of population in the primary city and per capita economic growth of the country, using the data for 113 nations over the period, 2000-2010. The concentration of population is measured in two ways, the ratio of the primary city's population to the total and to the second city. Using the ratio of the primary city's population to that of the entire nation, the empirical results neither show the robust negative relations nor the reverse U relation between primary city's concentration and economic growth. The ratio of the primary city to the second city however turns out to have a negative relation to per capita GDP growth. This result implies economic growth of a nation can be enhanced by decreasing the gap between the primary and the second ranked cities and does not support the reverse U hypothesis by Handerson(1974, 2003).

• The Journal of Fisheries Business Administration
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• v.37 no.3 s.72
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• pp.25-44
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• 2006

This paper tries to suggest reform proposals for the management policy of reported handicraft fisheries based on the intertidal - mudflat productivity. The paper started from the empirical analysis of the current situation of the handicraft fisheries around Seosan and Dangjin counties. The area of intertidal - mudflat around Seosan and Dangjin counties is approximately 855ha. The its ratio to the total areas in our country is 0.3%. By the way, the reported number of handicraft fisheries is 5,245, the ratio of which to the total number in our country is nearly 10.2%. The reason why there exists unbalance between the area of intertidal - mudflat and the reported number of handicraft fisheries is the political behavior of provincial governments. Therefore the paper tries to establish policy remedies focused on the confrontation against the opportunistic behaviors of provincial governments, such as the reform proposals for the Korea's fisheries act.

• Structural Engineering and Mechanics
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• v.14 no.4
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• pp.417-434
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• 2002

This paper explores the possibility of using a combination of the empirical mode decomposition (EMD) and the Hilbert transform (HT), termed the Hilbert-Huang transform (HHT) method, to identify the modal damping ratios of the structure with closely spaced modal frequencies. The principle of the HHT method and the procedure of using the HHT method for modal damping ratio identification are briefly introduced first. The dynamic response of a two-degrees-of-freedom (2DOF) system under an impact load is then computed for a wide range of dynamic properties from well-separated modal frequencies to very closely spaced modal frequencies. The natural frequencies and modal damping ratios identified by the HHT method are compared with the theoretical values and those identified using the fast Fourier transform (FFT) method. The results show that the HHT method is superior to the FFT method in the identification of modal damping ratios of the structure with closely spaced modes of vibration. Finally, a 36-storey shear building with a 4-storey light appendage, having closely spaced modal frequencies and subjected to an ambient ground motion, is analyzed. The modal damping ratios identified by the HHT method in conjunction with the random decrement technique (RDT) are much better than those obtained by the FFT method. The HHT method performing in the frequency-time domain seems to be a promising tool for system identification of civil engineering structures.

• Journal of Korean Academy of Nursing
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• v.42 no.1
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• pp.95-104
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• 2012

Purpose: The purpose of this study was to identify the effects of a home based exercise program for patients with stomach cancer who were undergoing oral chemotherapy. Methods: The home-based exercise program was developed from the study findings of Winningham (1990) and data from the Korea Athletic Promotion Association (2007). The home-based exercise program consisted of 8 weeks of individual exercise education and exercise adherence strategy. Participants were 24 patients with stomach cancer who were undergoing oral chemotherapy following surgery in 2007 or 2008 at a university hospital in Seoul. Patients were randomly assigned to either the experimental group (11) or control group (13). The effects of the homebased exercise program were measured by level of cancer related fatigue, NK cell ratio, anxiety, and quality of life. Data were analyzed using SPSS/WIN 13.0 version. Results: The degree of cancer related fatigue and anxiety in the experimental group decreased compared to the control group. The NK cell ratio and the degree of quality of life of experimental group increased while that of the control group decreased. Conclusion: This study result indicate the importance of exercise and provide empirical evidence for continuation of safe exercise for patients with cancer during their chemotherapy.