• Korean Journal of Optics and Photonics
• /
• v.13 no.3
• /
• pp.215-222
• /
• 2002

Using an in-situ ellipsometer, we monitored the growth curve of optical recording media in real time. For confirmation of the thickness control using in-situ ellipsometry, we analyzed the deposited multi-layer sample made of Ge-Sb-Te alloy film and ZnS-Si0$_2$ dielectric films using an exsitu spectroscopic ellipsometer. The target material in the first sputtering gun is ZnS-SiO$_2$ as the protecting dielectric layer and that in the second gun is Ge$_2$sb$_2$Te$_{5}$ as the receding layer. While depositing ZnS-SiO$_2$, Ge$_2$Sb$_2$Te$_{5}$ and ZnS-SiO$_2$ films on c-Si substrate in sequence, we measured Ψ $\Delta$ in real time. Utilizing the complex refractive indices of Ge$_2$Sb$_2$Te$_{5}$ and ZnS-SiO$_2$ obtained from the analysis of spectroscopic ellipsometry data, the evolution of ellipsometric constants Ψ, $\Delta$ with thickness is calculated. By comparing the calculated evolution curve of ellipsometric constants with the measured one, and by analyzing the effect of density variation of the Ge$_2$Sb$_2$Te$_{5}$ recording layer on ellipsometric constants with thickness, we precisely monitored the growth rate of the Ge-Sb-Te multilayer and controlled the growth process. The deviation of the real thicknesses of Ge-Sb-Te multilayer obtained under the strict monitoring is post confirmed to be less than 1.5% from the target structure of ZnS-SiO$_2$(1400 $\AA$)IGST(200 $\AA$)$\mid$ZnS-SiO$_2$(200$\AA$).(200$\AA$).

• Journal of the Earthquake Engineering Society of Korea
• /
• v.9 no.5 s.45
• /
• pp.53-61
• /
• 2005

In order to evaluate the limit earthquake resistance of multi-story steel frames influenced by the strength and stiffness ratios of members, a series inelastic response analysis were carried out. From the analysis results, the damage distribution rules of multi-story steel frames were proposed. Conclusions are summarized as follows; 1)As the stiffness ratios of beam and column becomes small, the damage concentrates on the lower end of columns of the first story. 2) Considering the strength and stiffness ratios of the beam and column with weak beam type mechanism, the equations predicting the damage distribution of multi-story steel flames were proposed. 3) Through the equation which was supposed in this study, it is speculated that the damage distribution of the rigid or semirigid beam collapse type multi-story steel structure building can be predicted.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.3 no.2
• /
• pp.313-319
• /
• 1999

We devise the 3 models of Multilayered Recurrent Prediction Neural Network(MLRPNN), which are obtained by modifying the Multilayered Perceptron(MLP) with 4 layers. We experimentally study the speech recognition performance of 3 models by a comparative method, according to the variation of the prediction order, the number of neurons in two hidden layers, initial values of connecting weights and transfer function, respectively. By the experiment, the recognition performance of each MLRPNN is better than that of MLP. At the model that returns the output of the upper hidden layer to the lower hidden layer, the recognition performance shows the best value. All MLRPNNs, which have 10 or 15 neurons in the upper and lower hidden layer and is predicted by 3rd or 4th order, show the improved speech recognition rate. On learning, these MLRPNNs have a better recognition rate when we set the initial weights between -0.5 and 0.5, and use the unipolar sigmoid transfer function in the lower hidden layer.

• Journal of the Korean Society of Radiology
• /
• v.14 no.1
• /
• pp.69-75
• /
• 2020

Multilayer mirrors have widely been used not only in the industry but also in the medical field. X-ray reflectivity was measured by X-ray diffractometer to evaluate the performance of W/C multilayer mirror with 40 layers. Genetic algorithm are used to obtain thickness, density, and interfacial roughness for each of the 40 layers. The existing uniform random selection causes a problem that the solution does not converge or the error increases even if it convergence. To reduce the time to calculate the fitness of the genetic algorithm, the genetic algorithm was written in C/C++ parallel programming. The genetic algorithm showed excellent scalability of linear time increase with increasing number of generation and population. The genetic algorithm was selected with uniform and Gaussian randomness of 1:1 to improve the convergence of solution. The improved genetic algorithm can be applied to characterize each layer of a sample with more than a few tens of layers, such as a multilayer mirror.

• Journal of the Korean Geotechnical Society
• /
• v.25 no.4
• /
• pp.77-90
• /
• 2009

In this study, experimental analysis was performed about lateral load capacity and behavior of laterally loaded-bored rigid piles in muti-layered soil conditions. Lateral pile load tests were performed for muti-layerd soils consisting of different relative density. Ultimated lateral load capacities were measured from lateral load-displacement curves and compared with estimated values using theoretical methods. Bending moments and unit lateral capacity distribution of surrounding piles were measured from attached strain gauges and earth pressure sensors on the pile. It was found that ultimated lateral load capacities were different from the muti-layered soil conditions, and measured values were lower than estimated values. The bending moment distributions of the pile were similar all the time. Unit lateral capacity distributions were a little different from muti-layered soil conditions, but basically similar to the distribution proposed by Prasad and Chari (1999).

• Journal of Educational Research in Mathematics
• /
• v.26 no.2
• /
• pp.189-204
• /
• 2016

As compared with the gender differences in the achievement of mathematics of the PISA 2009, the results of this study on the PISA 2012 show that the achievement of male students sharply increased, while that of female students maintained the status quo. Based on the premise that this result is derived from the ratio differences between male and female students of high level, this study analyzed the educational context variable effects on the achievements of gender differences observed between male and female students of high level. In particular, this study inquired into the factors which influence the gender difference, by analyzing the identical variables regarding Singapore and Finland of which the achievement of female students registers high among other top high-ranking countries of the PISA 2012. Hence, the binominal logistic multi-level analysis was conducted in order to consider the characteristics of hierarchical structure of PISA, and to compare the features of the educational context variable effects between the high level (above level 5) by country and the highest level (above level 6) by group. The analysis results are as follows: in terms of after-school learning time realized either in private lessons and private institutes, no significant effects were shown in any of the students of these three countries. In terms of after-school homework time, the students of Korea and Singapore gave significant influences on the probability which would be included in the group of high level or the highest level. In particular, regarding the variables which influence the probability of inclusion of Korean female students in the group of high level or the highest level, they correspond to "Homework set by teacher", "Attitude toward school: learning activities", "ESCS of School" and "Teacher-student relations". And "Cultural possessions at home" gave main influences on the probability of inclusion of the female students of Korea, Singapore and Finland in the group of the highest level.

• Journal of the Korean Data and Information Science Society
• /
• v.27 no.4
• /
• pp.935-946
• /
• 2016

In this paper, we analyzed wage determinants of the vocational high school graduates utilizing both individual-level and work region-level variables. We formulate the models in the way wage determination has multi-level structure in the sense that individual wage is influenced by individual-level variables (level-1) and work region-level (level-2) variables. To incorporate dependency between individual wages into the model, we utilize hierarchical linear model (HLM). The major results are as follows. First, it is shown that the HLM model is better than the OLS regression models which do not take level-1 and level-2 variables simultaneously into account. Second, random effects on sex, maester dummy and engineering dummy variables are statistically significant. Third, the fixed effects on business hours and mean wage of regular job for level-2 variables are statistically significant effect individual-level wages. Finally, parental education level, parental income, number of licenses and high school grade are statistically significant for higher individual-level wages.

• The Journal of the Korea Contents Association
• /
• v.16 no.1
• /
• pp.190-203
• /
• 2016

Based on the premise that a systematic career process was one of the essential elements of successful task performance both for individuals and the organization in the field of social welfare, this study set out to empirically analyze factors influencing the career commitment of social workers at a multidimensional level and provide practical implications for the directionality of career management on the basis of data with theoretical and statistical accuracy. For those purposes, the study collected individual and organizational characteristics data from 787 social workers at 46 agencies through a structured questionnaire and analyzed influential factors through the multilevel analysis technique by taking organizational effects into account. The analysis results show that explanations by the organization characteristics recorded significant 15% in the total variance of career commitment and that its influential factors included such significant variables as the protean career attitude, desire for growth, human network, and self-efficacy at the individual level and also the qualification compensation system at the organizational level. The study then proposed and discussed integrated practice strategies between individuals and agencies as the measures to promote career success through the activation of individual factors based on the consideration of organizational effects such as the application of an employee assistant program, provision of incentives to professional career development, and shift to a learning organization.

• Korean Journal of Social Welfare
• /
• v.68 no.3
• /
• pp.29-50
• /
• 2016

This study examined the determinants of housing affordability using the 2014 fact-finding survey of housing. This study identified the effects of characters of districts as well as the effects of characters of family and housing, taking advantage of HGLM(Hierarchical General Linear Model). The results of this study showed that male householder, higher education level, the monthly housing, higher satisfaction of environment of housing are the factors that increased the odds of living at unaffordable housing, but higher income, public transfer recipient, living at sub-standard housing, the Jensei housing are the factors that decreased the odds of living at unaffordable housing. And the higher housing price, the higher rent of the districts increased significantly the odds of living at unaffordable housing, but the higher rate of public housing of the districts decreased the odds of living at unaffordable housing. This study provides the basis that the price of housing and rent should be controled and the policy of public housing should be expanded for housing welfare.

• Journal of the Society of Disaster Information
• /
• v.8 no.4
• /
• pp.384-390
• /
• 2012

This study attempts to test the effects of neighborhoods on children and adolescents' alcohol, cigarette and marijuana use. Theoretically, this study was guided by Akers' (1998) SSSL model as potential explanations for understanding the linkage and provided partial test of the model. More specifically, it aims to test the mediation effects of one of core propositions of the SSSL model; whether differential association with deviant peers as well as with conforming peers mediates social disorganization of neighborhoods on adolescent substance and drug use in a different direction. Using multilevel regression techniques with robust standard error, this study utilized data from 1,791 children and adolescents who were nested in 80 neighborhoods in Chicago. The findings of the study provide mixed supports for the SSSL model. That is, it found that there are not only mediation effects but also moderation effects of differential association on children and adolescents' substance and drug use.