• Journal of the Microelectronics and Packaging Society
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• v.27 no.1
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• pp.45-54
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• 2020

Recently, market demands of miniaturization, high interconnection density, and fine pitch of PCBs continuously keep increasing. Therefore, SLP (substrate like PCB) technology using a modified semi additive process (MSAP) has attracted great attention. In particular, SLP technology is essential for the development of high-capacity batteries and 5G technology for smartphones. In this study, the reliability of the microvia of hybrid SLP, which is made of conventional HDI (high density interconnect) and MSAP technologies, was investigated by experimental and numerical analysis. Through thermal cycling reliability test using IST (interconnect stress test) and finite element numerical analysis, the effects of various parameters such as prepreg properties, thickness, number of layers, microvia size, and misalignment on microvia reliability were investigated for optimal design of SLP. As thermal expansion coefficient (CTE) of prepreg decreased, the reliability of microvia increased. The thinner the prepreg thickness, the higher the reliability. Increasing the size of the microvia hole and the pad will alleviate stress and improve reliability. On the other hand, as the number of prepreg layers increased, the reliability of microvia decreased. Also, the larger the misalignment, the lower the reliability. In particular, among these parameters, CTE of prepreg material has the greatest impact on the microvia reliability. The results of numerical stress analysis were in good agreement with the experimental results. As the stress of the microvia decreased, the reliability of the microvia increased. These experimental and numerical results will provide a useful guideline for design and fabrication of SLP substrate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.9
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• pp.177-185
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• 2017

The purpose of this study was to investigate and analyze the correlations between the knowledge of, attitudes toward, and service requirements for dementia among nursing students. A descriptive study design was used. The participants were 584 nursing students attending K university. The collected data were analyzed by descriptive statistics, the t-test, ANOVA, Scheffe test, and Pearson's correlation coefficients using the IBM SPSS 21.0 program. The mean score of dementia knowledge was low($15.86{\pm}4.58$). The area with the highest correct answer rate for dementia knowledge was life impact(64.2%) and the disease progression area(39.6%) was the lowest. The attitude toward dementia ($45.15{\pm}4.59$) and service requirements($89.88{\pm}9.38$) were relatively high. There were positive correlations between dementia knowledge and dementia attitude(r=.11, p=.008) and service requirements(r=.21, p<.001) and between dementia attitude and service requirements(r=.34, p<.001). Therefore, accurate knowledge of dementia was closely related to positive attitudes. In conclusion, this studyis expected to provide the basic data for the development, application and evaluation of dementia education programs for nursing students.

• Journal of Korea Water Resources Association
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• v.50 no.5
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• pp.303-313
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• 2017

In environmental impact assessments for large urban development projects, the Korean government requires analysis of stormwater runoff before, during and after the projects. Though hydrological models are widely used to analyze and prepare for surface runoff during storm events, accuracy of the predicted results have been in question due to limited amount of field data for model calibrations. Intensive field measurements have been made for storm events between July 2015 and July 2016 at a sub-basin of the Gwanpyung-cheon, Daejeon, Republic of Korea using an automatic monitoring system and also additional manual measurements. Continuous precipitation and surface runoff data used for utilization of SWMM model to predict surface runoff during storm events with improved accuracy. The optimal values for Manning's roughness coefficient and values for depression storage were estimated for pervious and impervious surfaces using three representative infiltration methods; the Curve Number Methods, the Horton's Method and the Green-Ampt Methods. The results of the research is expected to be used more efficiently for urban development projects in Korea.

• Journal of Digital Convergence
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• v.13 no.10
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• pp.445-458
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• 2015

This research is aged 65 or older with chronic pain and social support, are subject to the elderly wanted to know the effect on depression and suicide intention. This research was done through targeting elderly with chronic pain who use welfare center. The data collection period from April 20 in 2014, implemented by May 20. finally 178 kinds of types of data were analyzed. The collected data is Person's correlation coefficient, and multiple regression analysis by using SPSS 18.0, t-test, ANOVA. In this research results chronic pain, depression and suicide was observed a significant correlation between the degree of social support appear also showed a significant negative correlation of depression and suicide. Also, chronic pain can affect the degree of social support, suicide was identified as the most powerful variable impact on depression. The elderly with Chronic pain is more severe the higher the degree of suicide, The results were lower social support is also of increasing depression and suicide. There fore family and social care and social support services need to develop for prevent depression and suicide for the elderly, also needs programs invention for chronic pain as well.

• Applied Biological Chemistry
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• v.50 no.3
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• pp.147-153
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• 2007

To search for a molecular design of a new breast cancerous inhibitory active compound, 2D-QSAR and HQSAR between the substituents of flavopiridol analogues as substrates and their breast cancerous inhibitory activities against MCF-7 cell were analyzed and discussed quantitatively. It was found that the dispersion with molecule and steric hindrance with substituents will have a tremendous impact on the inhibitory activities from the 2D-QSAR model (1). Also, MR constant is better than that of MS constant as animportant factor. The inhibitory activities from 2D-QSAR model (2) were dependent upon the optimum MR constant (MR = 126 $Cm^3/mol$). Optimized HQSAR model (V) exhibited the best predictability of the inhibitory activities based on the cross-validated $r^2_{cv}$($q^2$= 0.583) and non-cross-validated conventional coefficient ($r^2_{ncv}$= 0.982). From the contribution maps, the inhibitory activity by the imino group on $C_9$ atom was higher than that of the hydroxyl group of $C_8$ atom on the A ring in molecule. Therefore, we can confirm that the dispersion by substituents in molecule is the most important factor in inhibitory activities against MCF-7 cell.

• The Korean Journal of Financial Management
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• v.20 no.2
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• pp.41-72
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• 2003

The purposes of this paper are to build theoretical and empirically testable model to identify determining factors of ownership structure, and to analyze this model empirically using th Korea Stock Exchange panel data, and to test the impact of opening the stock market on the determinants of ownership structure. The determining factors of ownership structure identified in this paper include debt ratio, dividend, asset characteristics, profitability, growth business risk, size, institutional investors and chaebol-non chaebol dummy variable. Empirical panel estimation test reveals that this model can explain about $9\sim11%$ of the cross sectional variance in the equity ratio of large shareholders. The reasons that this model has too explanatory power are that some variables were measured with errors, and that there were some omitted variables in tested model. The regression results on the model variables ar generally in line with predictions. But the coefficient estimates on size is never significant. And it appears that the exogenous variable which explains opening the stock market has positive effect on the determinants of ownership structure.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.5
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• pp.323-334
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• 2020

Since boundary layer transition has a significant impact on the aero-thermodynamic performance of hypersonic flight vehicles, capability of accurate prediction of transition location is essential for design and performance analysis. In this study, γ-Re_θt model is improved to predict transition of hypersonic boundary layers and validated. A coefficient in the production term of the intermittency transport equation that affects the transition onset location is constructed and applied as a function of Mach number, wall temperature, and freestream stagnation temperature based on the similarity numerical solution of compressible boundary layer. To take into account a Mach number dependency of transition onset momentum thickness Reynolds number and transition length, additional correlation equations are determined as function of Mach number and applied to Re_θc and F_length correlations of the baseline model. The suggested model is implemented to a commercial CFD code in consideration of practical use. Analysis of hypersonic flat plate and circular cone boundary layers is carried out by using the model for validation purpose. An improvement of prediction capability with respect to variation of Mach number and unit Reynolds number is identified from the comparison with experimental data.

• The Journal of the Korea Contents Association
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• v.17 no.6
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• pp.55-62
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• 2017

The purpose of this study is to investigate the transitory and permanent growth effects of human capital of the Korean economy based on the analysis of the New Normal Era during the period 1970-2014. For the transitory effects, we found out that all the coefficients of capital and labor are significant above the 5% level, whereas the coefficients of labor and human capital are significant only at the 10% level during the period 1999~2014. In particular, in the case of 1% increase in the human capital, the actual growth rate raised up with the rate of 0.15% over a 45-year period. For the permanent growth effects, the coefficients of capital and labor are significant above the 5% level. Furthermore, sum of the coefficients of the capital and labor showed approximately 0.96~0.99, approaching to a unit, which implies that there is a constant returns scale with respect to these inputs. In particular, the coefficient of human capital at 0.064 is significant at the 10% level. This implies that the permanent growth effect of an additional index of human capital is about 0.64% the previous 45-year period.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.814-824
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• 2020

Recently, public interest in air pollutants has increased, and the Korean government and local governments have attempted to improve air quality. This study examined the secondary air pollutant contribution in Ulleung Island, Jeju Island, and Baengnyeong Island and compared the differences between them by analyzing the air pollution level and weather conditions in these regions. The weather conditions of the island regions, such as wind speed, precipitation, and sunshine duration, and the average concentration of air pollutants, such as SO₂, NO₂, CO, O₃, PM₁₀, PM_2.5, were examined. The correlation coefficient between air quality factors of each island region and weather conditions was calculated. Regression analysis was conducted by setting primary air pollutants, SO₂, NO₂, and CO as independent variables, and secondary air pollutants, O₃, PM₁₀, and PM_2.5 as dependent variables to identify the regional contribution and impact. Therefore, the government and local governments should establish air quality management for each island region.

• Korean Journal of Remote Sensing
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• v.36 no.3
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• pp.461-474
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• 2020

Korea launched Geostationary Environmental Monitoring Satellite (GEMS), a UV/visible spectrometer that measure pollution gases on 18 February 2020. Because satellite retrieval is an ill-posed inverse solving process, the validation with ground-based measurements or other satellite measurements is essential to obtain reliable products. For this purpose, satellite-based OMI and OMPS total column ozone (TCO), and ground-based Pandora TCO in Busan and Seoul were selected for future GEMS validation. First of all, the goal of this study is to validate the ground ozone data using characteristics that satellite data provide coherent ozone measurements on a global basis, although satellite data have a larger error than the ground-based measurements. In the cross validation between Pandora and OMI TCO, we have found abnormal deviation in ozone time series from Pandora #29 observed in Seoul. This shows that it is possible to perform inverse validation of ground data using satellite data. Then OMPS TCO was compared with verified Pandora TCO. Both data shows a correlation coefficient of 0.97, an RMSE of less than 2 DU and the OMPS-Pandora relative mean difference of >4%. The result also shows the OMPS-Pandora relative mean difference with SZA, TCO, cross-track position and season have insignificant dependence on those variables.In addition, we showed that appropriate thresholds depending on the spatial resolution of each satellite sensor are required to eliminate the impact of the cloud on Pandora TCO.