• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.2
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• pp.247-264
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• 2023

Objectives: The study was to examine the features of three-dimensional(3D) face dimensions and to develop fit test panels for the labor population using respirators in South Korea. Methods: This study was part of the first-year work of a two-year-project conducted at Occupational Safety and Health Research Institute in 2021. After 3D head dimensions data were collected from Size Korea Center managing Sixth Size Korea databases, 3D face dimensions DB for the South Korean labor population was established for 21 items of face dimensions in line with the ISO/TS 16976-2 and KS A ISO 15535. With the South Korean labor population 3D face dimensions DB, in accordance with the ISO/TS 16976-2, the descriptive statistics of 3D face dimensions were calculated and two fit test panels were developed. Results: A total of 2,752 subjects were finally determined and they were 52.9% for male, 41.2% for the highest age-group of 15-29, and residents in the capital area. Mean and standard deviation were obtained for each of the 21 3D face dimensions items for the South Korean labor population. Among the items, male and female face widths were 137.6±5.7 mm, 133.2±5.0 mm, respectively. Male and female face lengths were 116.6±7.0 mm, 107.8±6.8 mm, respectively. Two new South Korean fit test panels, a bivariate test panel and a principal component analysis test panel, were developed using the 3D face dimensions DB as well. Conclusions: Using the 3D face dimensions DB, the mean and standard deviation were featured for each of the 21 items and also the two fit test panels were newly developed in the study. It is suggested that the study outputs should be utilized practically and effectively in selection, use, and management of respirators at work, expecting that respiratory protection can be furthermore improved for respirator users including labor population across the country.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.1
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• pp.151-157
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• 2019

This study is about the process capability index (PCI). In this study, we introduce several indices including the index $C_{PR}$ and present the characteristics of the $C_{PR}$ as well as its validity. The difference between the other indices and the $C_{PR}$ is the way we use to estimate the standard deviation. Calculating the index, most indices use sample standard deviation while the index $C_{PR}$ uses range R. The sample standard deviation is generally a better estimator than the range R. But in the case of the panel process, the $C_{PR}$ has more consistency than the other indices at the point of non-conforming ratio which is an important term in quality control. The reason why the $C_{PR}$ using the range has better consistency is explained by introducing the concept of 'flatness ratio'. At least one million cells are present in one panel, so we can't inspect all of them. In estimating the PCI, it is necessary to consider the inspection cost together with the consistency. Even though we want smaller sample size at the point of inspection cost, the small sample size makes the PCI unreliable. There is 'trade off' between the inspection cost and the accuracy of the PCI. Therefore, we should obtain as large a sample size as possible under the allowed inspection cost. In order for $C_{PR}$ to be used throughout the industry, it is necessary to analyze the characteristics of the $C_{PR}$. Because the $C_{PR}$ is a kind of index including subgroup concept, the analysis should be done at the point of sample size of the subgroup. We present numerical analysis results of $C_{PR}$ by the data from the random number generating method. In this study, we also show the difference between the $C_{PR}$ using the range and the $C_P$ which is a representative index using the sample standard deviation. Regression analysis was used for the numerical analysis of the sample data. In addition, residual analysis and equal variance analysis was also conducted.

• Journal of Korea Port Economic Association
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• v.27 no.1
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• pp.185-212
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• 2011

The purpose of this paper is to show the empirical analysis way for measuring the seaport efficiency by using the previous radial model and the newly modified non-radial models( panel additive model, panel RAM model, and panel SBM model)with Spearman rank order correlation coefficient(SROCC) for 20 Korean ports during 11 years(1997-2007) for 1 inputs(port investment amount) and 4 outputs(Number of Ship Calls, Port Revenue, Customer Satisfaction Score for Port Service and Container Cargo Throughput). The main empirical results of this paper are as follows. First, consistency ratio of SROCC in terms of efficiency scores between radial and panel Additive model was over about 76% and overall consistency ratio was about 71.6%. Second, an efficiency of panel RAM model was higher than that of radial model with similarity. However, panel SBM model shows the very similar efficiency scores with panel radial model. Third, the slack size of radial model is smaller compared to non-radial model. Models' ranking orders in terms of efficiency scores, number of efficient ports are panel RAM model, panel SBM model, and radial model. The order from the minimum efficiency scores was the same order like just before. The policy implication to the Korean seaports and planner is that Korean seaports should introduce the new methods like non-radial models(panel additive model, panel RAM model, and panel SBM model) for measuring the port performance.

• Korean Journal of Construction Engineering and Management
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• v.10 no.5
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• pp.113-122
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• 2009

The domestic construction market started to expand steadily since 1970s. The building market which utilizes a sandwich panel with advantages of economical construction expenses and convenient construction has grown rapidly in recent years. However, the companies which specialize in constructing sandwich panels are relatively small or medium size, compared with other construction companies. As a result, studies on the improvement of productivity have not been conducted sufficiently. In this study, the construction sites of sandwich panel are investigated, and the work processes by each team are analyzed. Additionally, the productivity and the construction cost of each work group are analyzed by constructing a model using the Web-Cyclone. It analyzed sensitivities about change of productivity and work costs following in processing place of the panel which is one of the productivity effect factors, so it assayed the optimized productivity by each work group and work costs. Analysis showed that 30% of productivity has improved compared with the factory processing work group, and analysis of work costs showed that about 15% of work costs was increased. Also sensitivity analysis of opening ratio showed that the work costs optimization will be accomplished when about 20% of opening was processed from the factory.

• Journal of Preventive Medicine and Public Health
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• v.44 no.5
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• pp.191-200
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• 2011

Objectives: The goal of this paper is to examine the social network effects on post-traumatic sdress disorder (PTSD) in female North Korean immigrants who entered South Korea in 2007. Specifically, it attempts to verify if the density and composition of networks make a difference after controlling for the network size. Methods: A multivariate logistic regression is used to probe the effects of social networks using the North Korean Immigrant Panel data set. Because the data set had only completed its initial survey when this paper was written, the analysis was cross-sectional. Results: The size of the support networks was systematically related to PTSD. Female North Korean immigrants with more supporting ties were less likely to develop PTSD, even after controlling for other risk factors (odds-ratio for one more tie was 0.8). However, once we control for the size of the network, neither the density nor the composition of the networks remains statistically significant. Conclusions: The prevalence of the PTSD among female North Korean immigrants is alarmingly high, and regardless of the characteristics of supporting network members, the size of the supporting networks provides substantial protection. This implies that a simple strategy that focuses on increasing the number of supporting ties will be effective among North Korean immigrants who entered South Korea in recent years.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.91-94
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• 2006

In this paper, in order to get micro or nano size optical patterns, an analytical and experimental investigation on a LGP (light guide plate) injection molding process has performed. The LGP, which diffusing and emitting the light from the CCFL or the LEDs to the panel front direction uniformly, typically has an under 1mm thick base substrate and numerous 60 to $170{\mu}m$ width and 6 to $10{\mu}m$ thick dot patterns on it. Generally, the small size LGPs, for mobile devices, have been and are being made of PMMA through the injection molding process. However, the substrate thickness and the dot pattern size are decreasing, it becomes hard to fill the micro to sub-micro cavities completely. To investigate the flow behavior of resin in micro/nano cavities and identify the characteristics of the LGP injection molding process, we carried out the flow analyses with respect to the variations of the substrate thickness, the dot pattern size and the pitch of a cavity.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.11
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• pp.801-808
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• 2020

The purpose of the study is to find the factors that influence the financial leverage of Vietnam firms. The dependent variable is the financial leverage and the independent variables are firm size, asset structure, liquidity, growth opportunities, profitability, and firm age. The data are collected from Vietnam firms' annual financial reports in the period from 2010 to 2019. The study uses a sample of 448 Vietnam listed firms in the period. We also employ a panel regression model with pooled OLS and fixed effect to analyze the firms' financial data. The results of the model showed that financial leverage (FL) has a negative relationship with some factors such as asset structure (AS), liquidity (LQ), growth opportunities (GRW), profitability (ROA), and firm age (AGE) in the fixed effect regression. It means that when liquidity, profitability, and firm age increase, firms' financial leverage will decrease. While firms' financial leverage has still a positive relationship with the firm size (SIZE) in the model. As a result, when firm size increases, financial leverage will increase, too. The results showed that models are fit for the research and can be used to predict future findings. It is also useful for enterprises, financial advisors, investors, as well as the financial managers.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.2
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• pp.289-295
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• 2021

This study investigates the role of corporate governance in the dividend decision of 198 non-financial companies listed on the Colombo Stock Exchange of Sri Lanka, over the period from 2009 to 2016. Four corporate governance indicators are used in this study; managerial ownership, the board size, board independence, and CEO duality. Furthermore, this study considers three control variables such as profitability, firm size, and corporate tax. This study employed the Generalized Method of Moments (GMM) model to estimate the regression models on panel data study. The major contribution of this study is exploring the insight into the effect of corporate governance factors on dividend decisions. The results of the study revealed that managerial ownership showed a significant positive impact on the dividend payout ratio. Board size showed a significant positive influence on the dividend payout ratio. Board independence negatively but significantly influenced the dividend payout ratio. CEO duality showed an insignificant negative impact on the dividend payout ratio. In the framework of these CG indicators, Sri Lankan listed firms are recommended to have dispersed ownerships, large Board size and maintain a balance of power and authority by separating the individual who is assuming the position of the CEO from the Chairperson of the Board and maintain at least two independent directors.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.877-880
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• 2004

A method of improving device performance of OTFT was investigated. The mobility of device is more than 0.51 $cm^2$/Vs and $I_{on}/I_{off}$ is higher than $10^6$. An Active-matrix LCD driven by OTFT was fabricated. The resolution of this panel is 64 ${\times}$ 128 pixels and the pixel size is 550 ${\mu}m$ ${\times}$ 550 ${\mu}m$.

• Management Science and Financial Engineering
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• v.10 no.1
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• pp.43-52
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• 2004

This paper empirically investigates potential factors that might affect firms' incentives to license out technology. The analysis is done with the help of a panel data set of observed licensing transactions involving U.S. public companies in high-technology industries. The important explanatory factors relate to the firm characteristics such as the company's stock of technological knowledge (patent stock). prior involvement in technology licensing. the company size, R&D intensity and capital expenditure. The results suggest that there seems to be significant inter-sectoral differences as well as similarities in determinants of the propensity to transfer technology through licensing agreements.