• Journal of the Korean Society for Precision Engineering
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• v.12 no.2
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• pp.48-58
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• 1995

A micro positioning system using piezoelectric actuators have very wide application region such as ultra-precision machine tool, optical device, measurement systen. In order ro keep a high precision displacement resolution, they use a position sensor and feedback the error. From the practical point of view, a high-resolution displacement sensor system are very expensive and difficult to guarantee such sensitive sensors work properly in the hard opera- tion environment of industry. In this study, a micro-positioning grinding table which does not require position sensor but uses piezoelectric voltage feedback, has been developed. It is driven by hystersis-considering reference input voltage which calculated from computer and then uses actuator/sensor characteristics of piezoelectric materials. From the result of experiments we proved a fast and stable response of micro-positioning system and suggested efficient technique to control the piezoelectric actuator. And through grinding experiments, it is revealed that a characteristics of ground surfaces transient to plastic deformation as extremely small depth of grinding.

• Smart Media Journal
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• v.11 no.2
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• pp.53-62
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• 2022

Due to the accelerated global warming phenomenon after industrialization, the frequency of changes in the existing environment and abnormal climate is increasing. Agriculture is an industry that is very sensitive to climate change, and global warming causes problems such as reducing crop yields and changing growing regions. In addition, environmental changes make the growth period of crops irregular, making it difficult for even experienced farmers to easily estimate the growth stage of crops, thereby causing various problems. Therefore, in this paper, we propose a CNN model for estimating the growth stage of crops. The proposed model was a model that modified the pooling layer of ResNet, and confirmed the accuracy of higher performance than the growth stage estimation of the ResNet and DenseNet models.

• Journal of Wellbeing Management and Applied Psychology
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• v.7 no.2
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• pp.31-37
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• 2024

Purpose: Pop-up stores have emerged in the retail industry in recent years, offering consumers a new shopping experience for a limited time and location, and are used for a variety of purposes, including driving purchase behavior. In particular, they have become an important marketing tool among Gen MZ consumers who are quick to acquire information and sensitive to trends. Therefore, this study aims to analyze the impact of pop-up store characteristics on the purchasing behavior of MZ consumers. Research design, data and methodology: Based on a qualitative research approach, the study analyzed successful pop-up stores in Korea to closely examine how the limited operating period and experience-oriented marketing strategy of pop-up stores affect the perceptual attitudes and purchase decision process of Generation MZ. Results: The results of the case study revealed that selling limited edition items, maximizing customer experience factors, and differentiated concepts are the main factors that positively influence the purchase behavior of Gen MZ consumers. These factors contribute to the enhanced purchasing behavior of Gen MZ, making pop-up stores an effective marketing strategy. Conclusions: Pop-up stores are more than just a sales space, but an important communication channel that can strengthen the emotional connection with Gen MZ and effectively communicate brand values. This study provides useful insights for brands and companies to develop marketing strategies for MZ.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.32 no.1
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• pp.1-9
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• 2024

The unmanned aerial vehicle industry has developed a lot, but the possibility of accidents is increasing due to potential risks. In this study, SHELL models and HFACS were used to analyze unmanned aerial vehicle accidents in the UK and to identify the main causes and characteristics of accidents. The main cause analyzed by the SHELL model was identified as an abnormality in the alarm system. The main cause of the accident analyzed by HFACS was identified as the technical environment. The common cause identified by the SHELL model and HFACS was identified as a mechanical problem of unmanned aerial vehicles. This is due to the lack of accurate information or functionality of the alarm system in the operator interface, which often prevents the operator from responding to sensitive information. Therefore, in order to prevent civil UAV accidents, the stability and reliability of the system must be secured through regular inspections of the UAV system and continuous software updates. In addition, an ergonomic approach considering human interfaces is needed when developing technologies.

• Annals of Occupational and Environmental Medicine
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• v.34
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• pp.12.1-12.11
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• 2022

Background: Gender equality in the workplace remains a challenge. This study aimed to investigate the gender gap of human resources in the field of occupational safety and health (OSH) in Korea. Methods: Several national statistical data that can confirm the gender distribution of personnel in the OSH sector were reviewed. The gender distribution of industrial technical manpower statistics, professional certificate holders in the OSH field, and the status of the appointment of safety and health managers by industry was analyzed. Results: The distribution of professionals in the OSH sector in Korea had a large gender gap with a small number of women. In particular, the proportion of women in the safety field was lower than that in the health field. In the younger age group, while the proportion of women is increasing, the gender gap tends to decrease. Conclusions: Few data are available to understand the gender-related aspects of OSH professions. Nevertheless, our results provide basic information for initiating a discussion on the necessity of establishing gender-sensitive culture and policies in the OSH sector.

• Applied Chemistry for Engineering
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• v.35 no.4
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• pp.341-345
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• 2024

Common adhesives contain harmful chemicals, posing risks to humans and the environment. Basil seeds, an underutilized resource, can offer a solution. We extracted mucilage from basil seeds and found that altering the basil seed mucilage (BSM) to water ratio allowed us to control the adhesive strength. As the concentration of BSM increased and the water evaporated, adhesive strength improved. BSM can serve as both an adhesive and pressure-sensitive adhesive. This research showcases BSM's impressive strength and stability, making it a promising eco-friendly industrial adhesive option from plant-based sources, revolutionizing the adhesive industry.

• Journal of Microbiology and Biotechnology
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• v.13 no.5
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• pp.717-724
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• 2003

A newly isolated Citrobacter sp. Y19 catalyzes the CO-dependent $H_2$ production (biological water-gas shift reaction) by the actions of CO dehydrogenase (CODH) and hydrogenase. Y 19 requires $O_2$ for fast growth, but its $H_2$ production activity is significantly inhibited by $O_2$. In the present study, the effect of $O_2$ on the activities of CODH ard hydrogenase was investigated quantitatively in both whole cells and broken cells, based on CO-dependent or methyl viologen (MV)-dependent $H_2$ production in addition to CO-dependent MV reduction. In crude cell extracts, CODH activity was mostly found in the soluble fraction. Inactivation of CODH and hydrogenase activities by $O_2$ followed the first-order decay kinetics, and the dependence of the rate constants on $O_2$ partial pressure could be expressed by the Michaelis-Menten equation. In whole cells, the maximum deactivation rate constants ($k_{d,max}$ of hydrogenase and CODH were quite similar: $0.07{\pm}0.03 min^{-1}\;and\;0.10{\pm}0.04 min^{-1}$, respectively. However, the first-order rate constant ($k_{d,max}/K_s$) of CODH ($0.25\;min^{-1}\;atm^{-1}$) at low $O_2$ partial pressures was about 3-fold higher than that of the hydrogenase, since the half-saturation constant ($K_s$) of CODH was about half of that of hydrogenase. In broken cells, both enzymes became significantly more sensitive to $O_2$ compared to the unbroken cells, while $k_{d,max}/K_s$ increased 37-fold for hydrogenase and 6.7-fold for CODH. When whole cells were incubated under anaerobic conditions after being exposed to air for 1 h, hydrogenase activity was recovered more than 90% in 2 h suggesting that the deactivation of hydrogenase by $O_2$ was reversible. On the contrary, CODH activity was not recovered once deactivated by $O_2$ and the only way to recover the activity was to synthesize new CODH. This study indicates that $O_2$ sensitivity of $H_2$ production activity of Citrobacter sp. Y19 is an important drawback as in other $H_2-producing$ bactria.

• Korean Journal of Construction Engineering and Management
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• v.20 no.1
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• pp.41-51
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• 2019

With the aging of the population and the slowdown of the job market, elderly workers make up a large portion of the construction workforce. Also, due to the nature of the construction industry, where outdoor work is frequent, the weather has a more sensitive impact on elderly workers than on younger ones. The study aims to analyze the degree of weather risks exposed to elderly workers in the construction industry using the measure of work loss days. To that end, construction accidents that affected 28,514 elderly workers in seven cities from 2012 to 2016 (a total of 12,789 days) were analyzed to calculate work loss days per different weather factors. The results show that the elderly workers were seriously affected when the temperature was between $-12^{\circ}C$ and $-10^{\circ}C$, humidity between 55% and 60%, precipitation between 128mm and 181mm, and wind speed between 5.5m/s and 6.5m/s, with the highest work loss days. The combined effects between the weather factors were also analyzed to identify the conditiosn that leaded to high work loss days of elderly workers. This study contributes to effective safety management and pleasant working environment between weather factors and shedding light on the relationship between weather factors and work loss days of elderly workers.

• Journal of Animal Science and Technology
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• v.66 no.5
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• pp.949-961
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• 2024

The annual forage crop production system, enclosing silage corn (Zea mays L.) and following cool-season annual forage, can enhance forage production efficiency where available land is limited for pasture production. In this forage production system, successful silage corn cultivation has a significant value due to the great yield of highly digestible forage. However, some untimely planting or harvesting of corn due to changing weather often reduces biomass and feeding values. Therefore, a study was conducted to quantify the corn silage biomass reductions by the deviations from optimum planting soil temperature and optimum growing degree day (GDD). The approximations of maximum corn production were estimated based on field trial data conducted between 1978 and 2018 with early, medium, and late-maturity corn groups. Based on weather data, the recorded planting dates and harvest dates were converted into the corresponding trials' soil temperatures at planting (STP) and the GDD. The silage corn biomass data were regressed against STP and GDD using a quadratic function. The maximum biomass point was modeled in a convex upward quadratic yield curve and the optimum STP and GDD were defined as those values at the maximum biomass for each maturity group. Optimized STP was at 16.6℃, 16.2℃, and 15.6℃ for early, medium, and late maturity corn groups, respectively, while optimized GDD at harvest was at 1424, 1363, and 1542℃. The biomass reductions demonstrated quadratic functions by the departures of STP or GDD. The 5% reductions were anticipated when STP departed from the optimum temperature by 2.2℃, 2.4℃, and 1.4℃ for early, medium, and late maturity corns, respectively; the same degree of reductions were estimated when the GDD departed by 200, 180, and 130℃ in the same order of the maturity groups. This result indicates that biomass reductions of late-maturity corn were more sensitive to the departures of STP or GDD than the early-maturity corn. Therefore, early maturing cultivars are more stable in biomass production in a silage corn-winter annual forage crop production system to enhance forage-based livestock production efficiency.

• Applied Chemistry for Engineering
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• v.24 no.2
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• pp.148-154
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• 2013

UV curable acryl resin, pressure-sensitive adhesives (PSAs), are used in many different parts in the world. In particular, PSAs has been used in the wafer manufacturing process of semiconductor industry. As wafers become much thinner, UV curable PSAs require more proper adhesion performance. In this study, acrylic PSAs containing hydroxyl groups were synthesized using monomers of 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, styrene monomer and 2-hydroxyethyl acrylate. Isocyanate modified UV curable PSAs were then prepared by the adduct reaction that facilitates the UV curing property via controlling the amount of methacryloyloxyehtyl isocyanate. The proper adhesion performance and UV curing behavior of UV curable PSAs with various hydroxyl values were studied, and experimental conditions were then optimized to raise the efficiency of wafer manufacturing process. It was found that in case of using the equivalent ratio of 1 : 1 isocyanate hardener used in the UV curable PSAs, the peel strength before the UV curing process decreased as the amount of hydroxyl groups increased in the PSAs. The peeling adhesive strength was also decreased with increasing UV dose due to high curing characteristics.