• The Journal of Industrial Distribution & Business
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• v.8 no.7
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• pp.63-70
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• 2017

Purpose - Due to the lack of physical activities and the increase of sedentary behaviors such as screen time, the health condition for contemporaries has been deteriorating. This study is designed to investigate how the use of worktable or tools unfit for body and sedentary behaviors can exercise influence on muscular skeletal disease and how it has an impact on lowering work efficiency and the quality of life with the medium of the muscular skeletal disease. Research design, data, and methodology - The research has developed a questionnaire with 5 hypothesis. The questionnaires were also made by interview and E-mail. 350 copies of questionnaires were distributed and 315 questionnaire were used for the analysis as valid data responses. SPSS ver.22.0 were used and made Cronbach's and reliability test, correlation, Baron & α Kenny 3 step mediated regression analysis. Results - The research has found that living environment factors have positive effect on the occurrence of musculosketal disease. Particularly, repeated use of unfit worktable or tools has a positive effect on the muscular skeletal disorder. And sedentary lifestyle also has a positive effect on the disease. The musculoskeletal disease caused by living environment has a positive impact on lowering the work efficiency. This study has also showed that the muscular skeletal disease has mediated the relationship between the living environment factors and the decrease of work efficiency due to musculoskeletal disease. The musculoskeletal disorders can effect the decrease of the quality of life as well, for the decrease of work efficiency has a positive effect on lowering the quality of life. Conclusions - Sedentary lifestyles, the use of worktable unfit for body, and the repeated use of a tool have caused the increase of muscular-skeletal diseases, and reduction of productivity as well as the hight cost of medical treatment for our contemporaries. Understanding the cause of disease morbidity, finding ways to prevent the disease, and educating people about them would contribute not only to improvement of individual health but also to the advancement of welfare for all.

• Journal of Distribution Science
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• v.14 no.3
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• pp.55-62
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• 2016

Purpose - Average using time of smart-phone for Korean people is 3 hours 39 minutes and most people who are using a computer at home and their workplace can be affected over force to neck and shoulder due to unstable body posture. musculoskeletal disorders which caused by unstable body posture can affect strongly to decrease work efficiency. So this research is designed to measure the effect of using computer & smart-phone on decreased work efficiency due to musculoskeletal disorders and mediating effect between decreased work efficiency and musculoskeletal disorders. Research Design, Data, and Methodology - The author has developed a questionnaire with 6 hypothesis on the basis of previous research result with 5 constructs. The questionnaires were also made by interview and E-mail. 300 copies of questionnaires were distributed and 282 questionnaire were used for the analysis as valid data responses. SPSS ver.21.0 were used and made Cronbach's α and reliability test, correlation, Baron & Kenny 3 step mediated regression analysis. Result - Cronbach's α shows 0.770~0.954 and C.R. is 0.963~0.997 which is higher than 0.7. and AVE was 0.867~0.933. So the data are all acceptable condition. Using for a long time of a computer & smart-phone has a positive effect on musculoskeletal disorders. This means, it can cause musculoskeletal disorders if people use a computer & smart-phone for a long time due to unstable body posture. And musculoskeletal disorders can effect strongly decrease work efficiency. This study also found out that a long time of using computer can cause musculoskeletal disorders rather than using smart-phone a long time. To check mediate effect of musculoskeletal disorders between using a computer & smart-phone and Decreased Work Efficiency, author used 3-step mediated regression analysis of Baron & Kenny (1986). Using a computer for a long time mediate partially and using a smart-phone for a long time mediate completely. This means that using a smart-phone a long time is not the actual reason to decrease work efficiency. But using level of smart-phone is increasing rapidly day by day. So we need to make additional research about this matter seriously. Conclusion - Nowadays, people can not live on without a computer & smart-phone even a moment. But, using a computer for a long time will affect to cause musculoskeletal disorders and it will effect strongly to decrease work efficiency. Before, we thought over that musculoskeletal disorders were diseases of elder people. But, we found out from this study that musculoskeletal disorders can be happen to any people, even children, or workers in heavy industry or engaged in brain work. So we need to be careful when we use a computer for a long time. People also need to be careful to keep correct body posture when using both a computer and smart-phone since a smart-phone became more popular and using time level became longer. Due to increased income and living standard of people, physical growth of young people is so rapid. But the physical environment of society is not suitable for them since it can not follow up the speed of growth. Suitable work table is very important to prevent musculoskeletal disorder which can affect decrease work efficiency. For a person, a society or country, increased productivity is very important since it can directly connected to the job satisfaction. Education and reeducation for the people is also important, but to teach them how to keep good condition of health will be more important since it can increase the quality of work efficiency and quality of life. Computer and Smart-phone is one the best invention of modern society, but it can cause mental and physical disease which can affect decrease work efficiency and productivity. So it is necessary to observe attentively for the situation continually.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.4
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• pp.187-191
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• 2004

In this work, we used the PCID simulator for simulation of solar cell and examined the effect of front-back surface recombination velocity, minority carrier diffusion length, junction depth and emitter sheet-resistance. As the effect of base thickness, the efficiency decreased by the increase in series resistance with the increase of the thickness and found decrease in efficiency by decrease of the current as the effect of the recombination. Also, as the effect of base resistivity, the efficiency increased somewhat with the decrease in resistivity, but when the resistivity exceeded certain value, the efficiency decreased as a increase in the recombination ratio. The optimum efficiency was obtained at the resistivity 0.5 $\Omega$-cm, and thickness $100\mu\textrm{m}$. We have successfully achieved 10.8% and 13.7% efficiency large area($103mm{\times}103mm$) mono-crystalline silicon solar cells without and with PECVD silicon nitride antireflection coating.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.237-238
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• 2023

When primer is applied manually, adhesion performance decreases due to a decrease in primer penetration performance on the surface, and construction period delay may occur due to a long time due to a decrease in work efficiency when a large area is worked using a conventional roller. In addition, in the case of the roller method, precision work in corners and narrow spaces is not possible, so it is urgent to come up with measures to ensure uniform quality. In addition, secondary work occurs to remove fine powder from the surface before primer application, resulting in construction period delay due to the rise of the working stage. Therefore, in this study, equipment was used instead of manual work for primer work, and as a result, penetration performance and adhesion performance were improved about twice. From these results, it was confirmed that favorable results such as improving work speed, securing high quality, improving the working environment, and resolving the shortage of functional workers can be obtained.

• Advances in Energy Research
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• v.3 no.3
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• pp.157-165
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• 2015

This research investigates the effect of natural dust accumulation on the glass cover of solar thermal energy conversion systems. Four similar, locally manufactured, flat plate solar collectors are used. All collectors are South oriented with tilt angle of $40^{\circ}$. The glass cover of one collector is kept clean of dust during the experimental period while the second collector is cleaned at the beginning of each month. The third collector is cleaned every two months while the fourth collector is kept un-cleaned throughout the experimental period of four months. The calculated parameters are the solar heat gain rates and the corresponding values of the thermal efficiency. The result of the present work indicates that the percentage of fractional reduction of the useful heat gain rate due to dust accumulation during a period of one and two months is 11.4% and 17.0%, respectively. The percentage decrease of thermal efficiency during the same duration periods is 4.0% and 6.1%, respectively. The percentage of fractional reduction of the useful heat gain rate due to dust accumulation during a period of three and four months is 27.8% and 31.9%, respectively. The percentage decrease of monthly thermal efficiency during the same duration period is 10.2% and 11.3%, respectively.

• International Journal of Contents
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• v.8 no.3
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• pp.20-25
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• 2012

Working in a hazardous environment can decrease work efficiency and cause a variety of occupational diseases. To prevent occupational accidents and build a refreshing and pleasant work environment, therefore, it is necessary to develop an application system through which a worker's safety can be monitored on a realtime basis and provide related services. Recently, smartphones have become very popular across the nation, with over 10 million users. As a result, a variety of application services have been developed and provided in diverse sectors. This study proposes a system structure to develop application services which monitor work environment using smartphones and examines its applicability through the implementation of server and client interfaces.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.1255-1255
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• 2022

Recently, research on digital twins to generate digital information and manage construction in real-time using advanced technology is being conducted actively. However, in the construction industry, it is difficult to optimize and apply digital technology in real-time due to the nature of the construction industry in which information is constantly fluctuating. In addition, inaccurate information on the topography of construction projects is a major challenge for earthmoving processes. In order to ultimately improve the cost-effectiveness of construction projects, both construction quality and productivity should be addressed through efficient construction information management in large-scale earthworks projects. Therefore, in this study, a 3D digital map-based AR site management work support system for higher efficiency and accuracy of site management was proposed by using unmanned aerial vehicles (UAV) in wide earthworks construction sites to generate point cloud data, building a 3D digital map through acquisition and analysis of on-site sensor-based information, and performing the visualization with AR at the site By utilizing the 3D digital map-based AR site management work support system proposed in this study, information is able to be provided quickly to field managers to enable an intuitive understanding of field conditions and immediate work processing, thereby reducing field management sluggishness and limitations of traditional information exchange systems. It is expected to contribute to the improvement of productivity by overcoming factors that decrease productivity in the construction industry and the improvement of work efficiency at construction sites.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.381-388
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• 1999

The existing methods for installation of long steel pipe pile have some uneconomical problems such as increase of installation cost and period due to the welding of two piles and removal of soil plug, and decrease of driving efficiency due to the increase of driving resistance by time effect during the welding of piles and removal of soil plug, etc. Thus, in this study, new installation method for long steel pipe pile is suggested to work out the existing problems, and calibration chamber tests are peformed to investigate both driving and economical efficiency for the suggested method. The test results showed that the new installation method has increase bearing capacity as well as reduce installation cost and period for long steel pipe piles as compared with existing methods.

• Journal of Computational Design and Engineering
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• v.1 no.2
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• pp.140-151
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• 2014

Storing, and the loading and unloading of materials at production sites in the manufacturing sector for mass production is a critical problem that affects various aspects: the layout of the factory, line-side space, logistics, workers' work paths and ease of work, automatic procurement of components, and transfer and supply. Traditionally, the nesting problem has been an issue to improve the efficiency of raw materials; further, research into mainly 2D optimization has progressed. Also, recently, research into the expanded usage of 3D models to implement packing optimization has been actively carried out. Nevertheless, packing algorithms using 3D models are not widely used in practice, due to the large decrease in efficiency, owing to the complexity and excessive computational time. In this paper, the problem of efficiently loading and unloading freeform 3D objects into a given container has been solved, by considering the 3D form, ease of loading and unloading, and packing density. For this reason, a Group Packing Approach for workers has been developed, by using analyzed truck packing work patterns and Group Technology, which is to enhance the efficiency of storage in the manufacturing sector. Also, an algorithm for 3D packing has been developed, and implemented in a commercial 3D CAD modeling system. The 3D packing method consists of a grouping algorithm, a sequencing algorithm, an orientating algorithm, and a loading algorithm. These algorithms concern the respective aspects: the packing order, orientation decisions of parts, collision checking among parts and processing, position decisions of parts, efficiency verification, and loading and unloading simulation. Storage optimization and examination of the ease of loading and unloading are possible, and various kinds of engineering analysis, such as work performance analysis, are facilitated through the intelligent 3D packing method developed in this paper, by using the results of the 3D model.

• Korean Journal of Materials Research
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• v.21 no.9
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• pp.491-496
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• 2011

Transparent conducting oxides (TCOs) used in the antireflection layer and current spreading layer of heterojunction solar cells should have excellent optical and electrical properties. Furthermore, TCOs need a high work function over 5.2 eV to prevent the effect of emitter band-bending caused by the difference in work function between emitter and TCOs. Sn-doped $In_2O_3$ (ITO) film is a highly promising material as a TCO due to its excellent optical and electrical properties. However, ITO films have a low work function of about 4.8 eV. This low work function of ITO films leads to deterioration of the conversion efficiency of solar cells. In this work, ITO films with various Zn contents of 0, 6.9, 12.7, 28.8, and 36.6 at.% were fabricated by a co-sputtering method using ITO and AZO targets at room temperature. The optical and electrical properties of Zn-doped ITO thin films were analyzed. Then, silicon heterojunction solar cells with these films were fabricated. The 12.7 at% Zn-doped ITO films show the highest hall mobility of 35.71 $cm^2$/Vsec. With increasing Zn content over 12.7, the hall mobility decreases. Although a small addition of Zn content increased the work function, further addition of Zn content over 12.7 at.% led to decreasing electrical properties because of the decrease in the carrier concentration and hall mobility. Silicon heterojunction solar cells with 12.7 at% Zn-doped ITO thin films showed the highest conversion efficiency of 15.8%.