• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.7
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• pp.929-935
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• 2013

This paper presents the results of sizing optimization of ahat-shaped stiffener on a rectangular stiffened panel. The stiffened panel is subjected to impact loading by a projectile with a velocity of 1500-2500 m/s. To determine the size of the hat-shaped stiffener, sizing optimization was performed. The sizing optimization consists of three functions: objective, constraint, and design functions. The objective function is used to maximize the fundamental frequency of the stiffened panel. The constraint function is that the stiffener volume is less than 10% of the plate volume. The design function is the dimensions of the hat-shaped stiffener. By using the stiffened panel with the optimized hat-shaped stiffener, a hypervelocity impact was simulated, and the velocity and kinetic energy on the optimized stiffener was obtained. To evaluate the impact reduction on the stiffened panel, the velocity and kinetic energy of the projectile was normalized and compared.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.84-96
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• 2022

In the worst case, a temporary ignition source (also known as transient combustibles) between two electrical panels can damage both panels. Mitigation strategies for electrical panel fires were previously developed using fire modeling and risk analysis. However, since they do not comply with deterministic fire protection requirements, it is necessary to analyze the boundary values at which combustibles may damage targets depending on various factors. In the present study, a sensitivity analysis of input variables related to the damage threshold of two electrical panels was performed for dimensionless geometry using a Fire Dynamics Simulator (FDS). A new methodology using a damage evaluation map was developed to assess the damage of the electrical panel. The input variables were the distance between the electrical panels, the vertical height of the fuel, the size of the fire, the wind speed and the wind direction. The heat flux was determined to increase as the vertical distance between the fuel and the panel decreased, and the largest heat flux was predicted when the vertical separation distance divided by one half flame length was 0.3-0.5. As the distance between the panels increases, the heat flux decreases according to the power law, and damage can be avoided when the distance between the fuel and the panel is twice the length of the panel. When the wind direction is east and south, to avoid damage to the electrical panel the distance must be increased by 1.5 times compared to no wind. The present scale model can be applied to any configuration where combustibles are located between two electrical panels, and can provide useful guidance for the design of redundant electrical panels.

• 한국정보디스플레이학회:학술대회논문집
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• 2001.08a
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• pp.3-8
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• 2001

This paper will review the state of the latest development of AMLCD manufacturing facilities for large Substrate and discuss the future technologies. The trend of the display size enlargement of Note book PC has hauled the enlargement of the mother glass substrate in past 10 years. The enlargement of a substrate size has brought about the productivity improvement of the TFT panel with process innovation as yet. Will this trend be continuing hereafter too? The issues of the processing and facilities related with the large square substrate and mask step reduction will be overviewed and the future processing and facilities will be discussed.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.3
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• pp.269-275
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• 2020

In this study, flexural tests of precast concrete panels according to the thickness of cross-sectional and the with or not of reinforcement were carried out in order to develop and assess of a lightweight precast concrete panel using ultra high performance concrete. For the test, four panels were fabricated, and consisted of one normal concrete panel and three ultra high performance concrete panels. As a test result, it was found that the plain precast panel using ultra high performance concrete had a lower flexural performance than the reinforced normal concrete panel, regardless of the cross-sectional size. The flexural performance of the hollow-sectional precast panel applying ultra high performance concrete, is improved by 150% compared to that of the reinforced normal concrete panel. That is, through additional performance verification and optimization of the cross-sectional design of the panel, the ultra high performance concrete precast panel can be made lighter. Also, the practical use of lightweight precast panels with ultra high performance concrete can be available through evaluation on shear, joint connection and anchoring, etc.

• Journal of Korea Port Economic Association
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• v.35 no.1
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• pp.57-76
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• 2019

This study deals with the determinants of employment productivity of transportation labor, who are the main agents of the transportation industry that has made significant contributions to our country's industrial development. The study selected the determinants of employment productivity using the Korea Labor and Income Panel Study data, and analyzed the effects of various factors using panel logistic regression, panel OLS model, and panel robust regression. The results were as follows. First, a more positive effect was shown when employees held a regular job, had a "high level of education", "joining the labor union" and "experiencing vocational training". Second, in the case of job security, having a "high level of education" and "joining the labor union" showed a more positive effect; further, job security was higher for employees who worked in a "big company" or were "married". Third, in the case of higher income productivity, higher values of "age", "academic ability" and "company size" had a more positive effect, whereas larger values of "education" and "health condition except job training" had a negative one. Fourth, in the case of job satisfaction, "female", "joining the labor union" and having a higher "income" or "job security" led to higher satisfaction and a better "health condition compared to an average person". Further, a higher "overall life satisfaction" and "economic level" led to lower job satisfaction. The analysis of the determinants of employment productivity of transportation business and seeking for improvement plan is expected to improve the employment productivity in the transportation business.

• Journal of Aerospace System Engineering
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• v.15 no.1
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• pp.86-94
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• 2021

PCB-based deployable solar panel is mainly used for CubeSat due to its lightweight and easy of electrical connection. However, as the size of solar panel increases, there is a limit to ensuring the structural safety of solar cells due to excessive dynamic displacement under launch vibration environment. In previous mechanical designs, for the minimization of dynamic deflection, panel stiffness is increased by applying additional stiffeners made of various materials such as aluminum or composite. However, it could have disadvantages for CubeSat design requirements due to limited mass and volumes. In this study, a high-damping 6U solar panel was proposed. It had superior damping characteristic with a multi-layered stiffener laminated with viscoelastic acrylic tapes. Basic characteristics of this solar panel were measured through free-vibration tests. Design effectiveness of the solar panel was validated through qualification-level launch vibration test. Based on test results, vibration characteristics of a typical PCB solar panel and the high-damping laminated solar panel were predicted and a comparative analysis was performed.

• East Asian Economic Review
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• v.16 no.2
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• pp.205-225
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• 2012

I use panel data of sales by the foreign subsidiaries of the U.S. MNCs to examine whether trading blocs create more or less FDI and the impacts on FDI of the extended market size created by forming blocs. By employing a region-fixed effects model, I find that countries forming trading blocs attract more FDI, particularly from non-member countries, but that FDI does not always increase with the market size of the blocs. As the market size increases, FDI increases only for large blocs. However, these findings are sensitive to model specifications. A policy implication is that a country considering forming or joining a trading bloc with a view to attract FDI may want to form a trading bloc with a country or countries with a large market size.

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.351-354
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• 2003

To inspect point-defect in LCD pannel, calculate period and eliminated pattern. And then find point-defect to compare block image with each period. First processing, Founded over point defects. To reduce wrong point defect. Next, label point-defects and eliminated not surpass fixed limit-size.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.407-408
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• 2012

• Journal of Labour Economics
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• v.37 no.1
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• pp.1-28
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• 2014

We use a set of Korea panel data to estimate effects of legal working hours reduction on actual hours worked and employment effects, through panel econometrics methods. Taking account of sequential decrease in legal hours worked since 2004, we estimate the relationship between legal and actual working hours by size of industries. It is found that one hour reduction of legal hours per week caused 0.44 to 1.05 actual hours worked on average per week, depending on different industrial sizes. Also, estimated employment effects were not unanimously determined, rather they turn out to be clearly size-dependent, which provide different results from exiting literature. Our analysis proposed in this work can be restrictive as, for instance, there is significant lack of data for foreign workers, particularly in the small-sized industries. Subsequent empirical analysis is expected.