• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.1
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• pp.13-21
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• 1992

In the previous study, car interior noise was analyzed using structural acoustic mode coupling coefficients and noise response in vehicle compartment model was simulated by the developed special purpose program. As a continued study, this paper presents a practical scheme for the interior noise reduction of a passenger car. Noisy panels on the vehicle compartment wall could be easily identified by the analysis using mode coupling coefficients. Numerical simulation for noise reduction was carried out on a simplified vehicle compartment model by using panel contribution factor and the noise reduction effect was verified by the structural modification test using Steel Skin (damping sheet).

• Journal of the Korean Society for Aviation and Aeronautics
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• v.15 no.4
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• pp.131-141
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• 2007

This paper identifies the productivity in the Global Air Transport Industry for the period of 1995-2001 by testing the Total Factor Productivity with tonqvist method. Based on panel data from 20 major international airline corporations which formed global strategic alliances, we find alliances make a considerably significant contribution to productivity increases. We also find that total factor productivity rate changed surprisingly in Air Transport Industry between pre- and post-Asian financial crisis period.

• Human Ecology Research
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• v.58 no.3
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• pp.343-356
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• 2020

This paper examines the associations of having a helper for domestic work or childcare and time spent on it by couples in South Korea. We use five waves of panel survey data from the Korean Longitudinal Survey of Women and Families (KLoWF), which allows longitudinal changes within couples over time that account for potential selection effects and unobserved heterogeneity among individuals. With fixed effects, we find outsourcing is associated with a decrease in wife's time spent on domestic work or childcare by 1 hour per week. However, the decrease is concentrated on the unemployed wife's time, but not employed wife's time. In addition, outsourcing is not a significant factor for husband's time and the husband's share of total contribution. This may be because wives are the main provider of domestic work and childcare in Korea regardless of employment status or having any helper. Due to unequal contributions between husband and wife, using outsourcing also neither alleviates the employed wife's contribution nor changes the husband's contribution. However, the results may be underestimated because there are more common and diverse types of outsourcing in a broad sense, such as going out for dinner, buying prepared food, and using dry cleaning services. We expect future studies to consider more broad types of outsourcing and examine how relations with the couple's time use at home are different by type.

• Structural Engineering and Mechanics
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• v.90 no.4
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• pp.391-401
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• 2024

The present study focuses on the effect of extension-bending coupling on the elastic stability (buckling) of laminated composite plates. These plates will be loaded under uni-axial or bi-axial in-plane mechanical loads, especially in the orthotropic or anti-symmetric cross-angle cases. The main objective is to find a limit where we can approximate the elastic stability behavior of angularly crossed anti-symmetric plates by the simple behavior of specially orthotropic plates. The contribution of my present study is to predict the explicit effect of extension-flexion coupling on the elastic stability of this type of panel. Critically, a parametric study is carried out, involving the search for the critical buckling load as a function of deformation mode, aspect ratio, plate anisotropy ratio and finally the study of the effect of lamination angle and number of layers on the contribution of extension-flexure coupling in terms of plate buckling stability. We use first-order shear deformation theory (FSDT) with a correction factor of 5/6. Simply supported conditions along the four boundaries are adopted where we can develop closed-form analytical solutions obtained by a Navier development.

• Journal of the Semiconductor & Display Technology
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• v.7 no.2
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• pp.35-38
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• 2008

This study shows the improvement of PR-Ashing rates in semi-conductor process using Atmospheric Plasma. Taguchi method is used to improve Ashing rates of photo-resist that is spread on the surface of a wafer. Improvement of Ashing rates is acquired through the decision of the effective factors and suitable combination of the factors. The results show the contribution rate of each factor and the effectiveness of Plasma for PR-Ashing process in this system.

• Asia pacific journal of information systems
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• v.20 no.3
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• pp.115-137
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• 2010

Information technology (IT) outsourcing, the use of a third-party vendor to provide IT services, started in the late 1980s and early 1990s in Korea, and has increased rapidly since 2000. Recently, firms have increased their efforts to capture greater value from IT outsourcing. To date, there have been a large number of studies on IT outsourcing. Most prior studies on IT outsourcing have focused on outsourcing practices and decisions, and little attention has been paid to objectively measuring the value of IT outsourcing. In addition, studies that examined the performance of IT outsourcing have mainly relied on anecdotal evidence or practitioners' perceptions. Our study examines the contribution of IT outsourcing to economic growth in Korean industries over the 1990 to 2007 period, using a production function framework and a panel data set for 54 industries constructed from input-output tables, fixed-capital formation tables, and employment tables. Based on the framework and estimation procedures that Han, Kauffman and Nault (2010) used to examine the economic impact of IT outsourcing in U.S. industries, we evaluate the impact of IT outsourcing on output and productivity in Korean industries. Because IT outsourcing started to grow at a significantly more rapid pace in 2000, we compare the impact of IT outsourcing in pre- and post-2000 periods. Our industry-level panel data cover a large proportion of Korean economy-54 out of 58 Korean industries. This allows us greater opportunity to assess the impacts of IT outsourcing on objective performance measures, such as output and productivity. Using IT outsourcing and IT capital as our primary independent variables, we employ an extended Cobb-Douglas production function in which both variables are treated as factor inputs. We also derive and estimate a labor productivity equation to assess the impact of our IT variables on labor productivity. We use data from seven years (1990, 1993, 2000, 2003, 2005, 2006, and 2007) for which both input-output tables and fixed-capital formation tables are available. Combining the input-output tables and fixed-capital formation tables resulted in 54 industries. IT outsourcing is measured as the value of computer-related services purchased by each industry in a given year. All the variables have been converted to 2000 Korean Won using GDP deflators. To calculate labor hours, we use the average work hours for each sector provided by the OECD. To effectively control for heteroskedasticity and autocorrelation present in our dataset, we use the feasible generalized least squares (FGLS) procedures. Because the AR1 process may be industry-specific (i.e., panel-specific), we consider both common AR1 and panel-specific AR1 (PSAR1) processes in our estimations. We also include year dummies to control for year-specific effects common across industries, and sector dummies (as defined in the GDP deflator) to control for time-invariant sector-specific effects. Based on the full sample of 378 observations, we find that a 1% increase in IT outsourcing is associated with a 0.012~0.014% increase in gross output and a 1% increase in IT capital is associated with a 0.024~0.027% increase in gross output. To compare the contribution of IT outsourcing relative to that of IT capital, we examined gross marginal product (GMP). The average GMP of IT outsourcing was 6.423, which is substantially greater than that of IT capital at 2.093. This indicates that on average if an industry invests KRW 1 millon, it can increase its output by KRW 6.4 million. In terms of the contribution to labor productivity, we find that a 1% increase in IT outsourcing is associated with a 0.009~0.01% increase in labor productivity while a 1% increase in IT capital is associated with a 0.024~0.025% increase in labor productivity. Overall, our results indicate that IT outsourcing has made positive and economically meaningful contributions to output and productivity in Korean industries over the 1990 to 2007 period. The average GMP of IT outsourcing we report about Korean industries is 1.44 times greater than that in U.S. industries reported in Han et al. (2010). Further, we find that the contribution of IT outsourcing has been significantly greater in the 2000~2007 period during which the growth of IT outsourcing accelerated. Our study provides implication for policymakers and managers. First, our results suggest that Korean industries can capture further benefits by increasing investments in IT outsourcing. Second, our analyses and results provide a basis for managers to assess the impact of investments in IT outsourcing and IT capital in an objective and quantitative manner. Building on our study, future research should examine the impact of IT outsourcing at a more detailed industry level and the firm level.

• Korean Journal of Social Welfare
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• v.64 no.2
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• pp.55-83
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• 2012

Self-employment rate is high in Korean labor market, while the income gap within self-employed is also high. Although, there are very few studies that addressed on the income inequality of self-employed. Thus, this study has measured the earnings inequality of self-employed by generalized entropy indices and decomposed inequality factor and trend. The empirical study is based on Korea Welfare Panel Study wave 1~4. The main result from this analysis is summarized in three points. Firstly, earnings inequality of self-employed is severely high and the earnings polarization within self-employed has become more serious in Korea. Secondly, this study provides the evidence that the main factor of earnings inequality of self-employed is the status of self-employment, education level, age group, workplace scale and industry. Thirdly, the contribution of relative changes in the incomes of the status of self-employment is the largest to the inequality trend. In terms of education level, age group and industry, the increase of inequality within group(pure effect) mainly attributes to the rise of earnings inequality of self-employed and the change effect of group composition contributes to deterioration of inequality.

• Knowledge Management Research
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• v.24 no.2
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• pp.87-115
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• 2023

This study aims to examine the causal relationships between sales and employment for public technology-based startups. Although there is a limit to statistical generalization due to the poor understanding of the actual conditions of public technology start-up companies, these companies were analyzed by classifying them into high-growth companise, potential growth companies, and other companies. In order to understand the causal relationship, and to estimate the time required to be effective, panel vector autoregression was applied. As a result, the performance creation mechanism was identified as government supoort and private investment was mutually causal with employment, sales did not cause employment, and employment caused sales. In other words, it was found that employment plays an mediator role in public technology based startups' performance mechanism. In addition, private investment had the effect of improving employment and sales in the short time than governments support, and showed that firms with high employment can attract government support and private investment. This study are academically meaningful in that they empirically revealed the process of performance creation, whereas previous studies had only shown whether there was an effect on performance. It also has a policy contribution by suggesting the need for effective policy promotion by considering the 'employment' factor, such as human resource support, as more important.

• Survey Research
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• v.10 no.2
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• pp.1-21
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• 2009

The purpose of this study is to compare the estimates of housework time by gender using two representative methods of time use study: Time Diary and Stylized Survey Questionnaire. Our analysis is based on the data from the Lifetime Use Survey(2004), which used time-diary questions, and the Korean Labor & Income Panel Study(KLIPS 2004), which used stylized questions on housework hours. The results show that men over-report their housework time in the stylized time use questions. In contrast, women under-report their housework time, which is unusual in the previous studies on response errors and reporting gap. Subgroup analysis shows that widowed/divorced men tend to over-report their contribution to housework more than other groups whereas among women, groups burdened with employed work, caring and housework underestimate their housework time. This reporting gap is explained by gendered norm and perception of time pressure. The theory to explain under-reporting of the housework time has been undeveloped in the previous studies. Our study suggests that perceptions of time pressure be an important factor to explain women's reporting gap of housework estimates.

• Korean Journal of Social Welfare
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• v.64 no.4
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• pp.163-188
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• 2012

This study examines recent trends in income inequality among the elderly in Korea. Aggregate income inequality trends are explained by examining evidence from inequality index decomposition by population subgroup and by income source. Data come from Korean Labor and Income Panel Study(KLIPS). The results are as follows. First, elderly income inequality increased from 1999 to 2002, and then decreased until 2008. Second, household composition changes appear to have disequalizing influence. The proportion of elderly people who are economically dependent on non-elderly family member or living with adult children has declined. Equalizing influence of private transfers also decreased between 2002 and 2008. These results indicate that the redistributive role of family has weakened over time. Third, the improvement of education level and changing occupational structure among the elderly household head contributed to increase in elderly income inequality. Fourth, earning's factor share has declined steadily, and the diminishing role of earnings provides equalizing influence on elderly income inequality from 2002 to 2008. Fifth, the impact of recent expansion of social insurance has changed over time. Inequality contribution of social insurance income increased from 1999 to 2002, and then decreased from 2002 to 2008.