• Korean Journal of Social Welfare Studies
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• v.41 no.1
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• pp.345-375
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• 2010

This study is aimed at investigating the effects of school violence on adolescent depression and suicide, where both the mediating effects of resilency and the gender diffences are considered. The data, collected from 664 high and middle school students, were examined by the statistics software SPSS 17.0 and AMOS 17.0, in which descriptive statistics, factor analysis, structural equation model analysis, and multi-group simultaneous analysis are utilized. As a result, it is shown from the structural equation modeling that school violence have positive effects on depression and suicide, but negative effects on family and academic resiliency. Both ego and family resiliency act as protective factors, negatively affecting the depression. In addition, the family resiliency had negative effects on suicide. The results of multi-group simultaneous analysis imply that school violence have different effects on suicide and family resiliency respectively, depending on gender differences. Female adolescents are affected more strongly than male adolescents.

• Honam Mathematical Journal
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• v.31 no.1
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• pp.109-124
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• 2009

Based on the observed data for Clarithromycin released, three commonly used inflow models: the power, the exponential, and the logarithmic models are considered. Among them, the power model is used most in practice for simplicity. Using the numerical parameter estimation techniques, the parameters appeared in the model equations are estimated. Through the numerical estimation results using the several experimental data sets, the exponential model turns out to be best among the three models. More specifically, the sum of squares of absolute errors and the sum of squares of relative errors for the exponential model are reduced by 80-95 % for the experimental data sets and 60-90 % for the noise added data sets compared with those for the power and logarithmic models. A typical experimental data set is used in this paper to show the estimation method and its numerical results. The proposed numerical method and its algorithm are designed for estimating the parameters appeared in the model differential equations for which the exact form of the solution is unknown in general. The methodology developed can be applied to more general cases such as the nonlinear ordinary differential equations or the partial differential equations.

• International Journal of Safety
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• v.1 no.1
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• pp.36-42
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• 2002

This paper is aimed at predicting the life of rubber insulating gloves under normal operating stresses from relatively rapid test performed at higher stresses. Specimens of rubber insulating gloves are subject to multiple stress conditions, i.e. combined electrical and thermal stresses. Two modes of electrical stress, step voltage stress and constant voltage stress are used in specimen aging. There are two types of test for electrical stress in this experiment: the one is Breakdown Voltage (BDV) test under step voltage stress and thermal stress and the other is lifetime test under constant voltage stress and temperature stress. The ac breakdown voltage defined as the break-down point of insulation that leakage current excesses a limit value, l0mA in this experiment, is determined. Because the very high variability of aging data requires the application of statistical model, Weibull distribution is used to represent the failure times as the straight line on Weibull probability paper. Weibull parameters are deter-mined by three statistical methods i.e. maximum likelihood method, graphical method and least squares method, which employ SAS package, Weibull probability paper and FORTRAN, respectively. Two chosen models for predicting the life under simultaneous electrical and thermal stresses are inverse power model and exponential model. And the constants of life equation for multistress aging are calculated using numerical method, such as Gauss Jordan method etc.. The completion of life equation enables to estimate the life at normal stress based on the data collected from accelerated aging test. Also the comparison of the calculated lifetimes between the inverse power model and the exponential model is carried out. And the lifetimes calculated by three statistical methods with lower voltage than test voltage are compared. The results obtained from the suggested experimental method are presented and discussed.

• The Journal of Fisheries Business Administration
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• v.53 no.1
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• pp.55-72
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• 2022

The domestic catch of squid is decreasing every year. Import volume is increasing to replace these domestic products. Import volume is expected to increase in the future, so it is necessary to study import substitution. Therefore, in this study, after selecting frozen squid, which accounts for the majority of imported squid, as the target fish species, China, Chile and Peru, which account for the majority of frozen squid imports, will be selected as the target countries for analysis. Then, the demand function of squid is estimated using the Rotterdam model, the inverse Rotterdam model, AIDS and inverse AIDS, which are the simultaneous equation demand types, and then elasticity is derived. After that, these models are compared in terms of significance, theoretical fit and practical fit.

• Korean Journal of Agricultural Science
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• v.49 no.1
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• pp.77-91
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• 2022

North-South Korea economic integration is progressing slowly given the sensitive responses to changes in internal and external conditions. Nevertheless, advanced discussions focusing on North-South Korean economic cooperation should continue. Given this background, various studies of the economic effects of economic integration between North and South Korea have been conducted, but research on agricultural issues has been limited. The purpose of this study is to analyze the impact of the economic integration of South and North Korea on the agricultural market. In this study, a simultaneous equation model was constructed using a growth model. Solow's growth accounting approach is used to construct a model for estimating the macroeconomic effect of North-South economic integration. Also, the construction of growth accounting formulas subdivided into South and North Korea as well as agriculture and non-agricultural fields during the construction of the growth model is a major research achievement and differentiates it from previous studies. It is expected that the results of this study will serve as basic information for preparing policy measures to promote integration. However, there are many limitations when estimating the economic effects of North-South agricultural integration and obtaining policy implications given the insufficient available statistical data on agriculture in North Korea and the lack of related studies in the agricultural field. Therefore, it should be noted that there is an inherent problem in that the analysis results vary greatly depending on the assumptions set, as there is inevitably no choice but to rely on many and strong assumptions.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.4 no.1
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• pp.34-44
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• 1992

A numerical model using Hybrid Element Method(HEM) is presented for the prediction of wave agitations in a harbor which are induced by the intrusion and transformation of incident short-period waves. A linear mild-slope equation including bottom friction is used as the governing equation and a partial absorbing boundary condition is used on solid boundaries. Functional derived in the present paper is based on the Chen and Mei(1974)'s concept which uses finite element net in the inner region and analytical solution of Helmholtz equation in the outer region. Final simultaneous equations are solved using the Gaussian Elimination Method. The model appears to be reasonably good from the comparison of numerical calculation with hydraulic experimental results of short-wave diffraction through a breakwater gap(Pos and Kilner, 1987). The problem of requring large computational memory could be overcome using 8-noded isoparametric elements.

• The Journal of Asian Finance, Economics and Business
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• v.4 no.1
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• pp.19-23
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• 2017

Based on a simultaneous-equation model consisting of aggregate demand and short-run aggregate supply, this paper estimates a reduced-form equation specifying that the equilibrium real GDP is a function of the real effective exchange rate, the government deficit as a percent of GDP, the real interest rate, foreign income, labor productivity, the real oil price, the expected inflation rate, and the interactive and intercept binary variables accounting for a potential change in the slope of the real effective exchange rate and shift in the intercept. Applying the exponential GARCH technique, it finds that aggregate output in Australia has a positive relationship with the real effective exchange rate during 2003.Q3 - 2013.Q2, the government deficit as a percent of GDP, U.S. real GDP, labor productivity and the real oil price and a negative relationship with the real effective exchange rate during 2013.Q3 - 2016.Q1, the real lending rate and the expected inflation rate. These results suggest that real appreciation was expansionary before 2013.Q3 whereas real depreciation was expansionary after 2013.Q2 and that more government deficit as a percent of GDP would be helpful to stimulate the economy. Hence, the impact of real appreciation or real depreciation on real GDP may change overtime.

• Structural Engineering and Mechanics
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• v.12 no.5
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• pp.527-540
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• 2001

A new sort of learning algorithm named whole learning algorithm is proposed to simulate the nonlinear and dynamic behavior of RC members for the estimation of structural integrity. A mathematical technique to solve the multi-objective optimization problem is applied for the learning of the feedforward neural network, which is formulated so as to minimize the Euclidean norm of the error vector defined as the difference between the outputs and the target values for all the learning data sets. The change of the outputs is approximated in the first-order with respect to the amount of weight modification of the network. The governing equation for weight modification to make the error vector null is constituted with the consideration of the approximated outputs for all the learning data sets. The solution is neatly determined by means of the Moore-Penrose generalized inverse after summarization of the governing equation into the linear simultaneous equations with a rectangular matrix of coefficients. The learning efficiency of the proposed algorithm from the viewpoint of computational cost is verified in three types of problems to learn the truth table for exclusive or, the stress-strain relationship described by the Ramberg-Osgood model and the nonlinear and dynamic behavior of RC members observed under an earthquake.

• Journal of Korea Society of Industrial Information Systems
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• v.6 no.4
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• pp.75-80
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• 2001

In this paper, we propose a new chaotic synchronization algorithm of using HVPM(Hyperchaotic Volume Preserving Maps) model. The proposed chaotic equation, that is, HVPM model which consists of three dimensional discrete-time simultaneous difference equations and shows uniquely random chaotic attractor using nonlinear maps and modulus function. Pecora and Carrol have recently shown that it is possible to synchronize a chaotic system by sending a signal from the drive chaotic system to the response subsystem. We proposed coupled synchronization algorithm in order to accomplish discrete time hyperchaotic HVPM signals. In the numerical results, two hyperchaotic signals are coupled and driven for accomplishing to the chaotic synchronization systems. And it is demonstrated that HVPM signals have shown the chaotic behavior and chaotic coupled synchronization.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.5
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• pp.365-376
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• 2022

This study aims to look into the causal relationships between corporate social responsibility and firm value, corporate social responsibility and institutional ownership, and firm value and institutional ownership. This study develops a triangle model of causal relationships among the three endogenous variables. Samples for this study are manufacturing companies listed on the Indonesia Stock Exchange for the period 2014-2018. The model is operated in the system of simultaneous equation models using the generalized method of moments technique to estimate parameter coefficients. After controlling the effects of trade-off/balancing capital structure and managerial ownership, the research findings show a positive causal relationship between CSR and firm value and firm value and institutional ownership. Institutional ownership has a positive effect on CSR, while the effect of CSR on institutional ownership is negative in the firms without managerial ownership and positive in the firms with managerial ownership. This study finds that the causal relationship between CSR and firm value is stronger after the trade-off/balancing of capital structure is included in the model. Capital structure has a convex effect on firm value and positively impacts institutional ownership. In addition, an independent commissioner has a negative impact on CSR but has no direct impact on firm value.