• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2009.06a
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• pp.435-438
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• 2009

A navigation aid buoy is a kind of safety facility for maritime navigation with a purpose of leading the vessels for navigating, docking and sail off. An advanced rechargeable battery is required for stable power supply for navigation aid buoy as the high magnitude LED lamps, real time location/control for navigation aids and e-Navigation support systems with maritime climate observation equipments have recently been deployed. This study is focused on the lithium battery, especially lithium polymer battery which is believed to be safer than the other types of batteries. The lithium polymer battery reviewed in this study is designed with $LiFePO_4$-based cathode, which has superior safety features to the oxide-based cathodes. Besides, a 3.6kWh battery pack has been built with the above-mentioned unit cells for the purpose of comparative research with lead acid battery system.

• Journal of the Korea Society of Computer and Information
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• v.24 no.11
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• pp.109-117
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• 2019

Recently, the invasion of privacy in medical information has been issued following the interest in the secondary use of mass medical information. The mass medical information is very useful information that can be used in various fields such as disease research and prevention. However, due to privacy laws such as the Privacy Act and Medical Law, this information, including patients' or health professionals' personal information, is difficult to utilize as a secondary use of mass information. To do these problem, various methods such as k-anonymity, l-diversity and differential-privacy that can be utilized while protecting privacy have been developed and utilized in this field. In this paper, we discuss the differential privacy processing of the various methods that have been studied so far, and discuss the problems of differential privacy using Laplace noise and the previously proposed differential privacy. Finally, we propose a new scheme to solve the existing problem by adding a 1-bit status field to the last column of a given data set to confirm the response to queries from analysts.

• Journal of the Korea Convergence Society
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• v.12 no.12
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• pp.551-562
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• 2021

This study aimed to identify the effect of resilience and positive psychological capital on hospital nurses' professional quality of life. A cross-sectional survey design was utilized to investigate 221 general hospital nurses from June 1 to 30, 2021. Professional quality of life (ProQOL), which is conceptualized with three sub-dimensions (compassion satisfaction, burnout, and secondary traumatic stress), resilience, and positive psychological capital variables were measured. There was a positive relationship between compassion satisfaction and resilience, positive psychological capital, and a negative relationship among burnout, secondary traumatic stress, and the other variables in this study. The main factors influencing compassion satisfaction were resilience, and positive psychological capital, which explained about 47% of compassion satisfaction. Burnout was influenced by resilience, positive psychological capital, and work pattern, and these variables explained about 37% of burnout. Notably, it was found that resilience was the most crucial factor in nurses' compassion satisfaction, and positive psychological capital was the most crucial factor in nurses' burnout. Thus, it is suggested to develop and verify the effectiveness of a resilience improvement program and positive psychological intervention program to strengthen the internal resources of hospital nurses.

• Journal of the Korean Electrochemical Society
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• v.22 no.3
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• pp.122-127
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• 2019

In this study, we investigate the electrochemical performance of lithium terephthalate (LTA) battery using graphite coated metal current collector to overcome the disadvantages of organic batteries which is high interfacial resistance between current collector and electrode. The LTA anode material is synthesized by acid-based ion exchange reaction without impurities. The contact properties between stick-type LTA-based electrode and graphite coated current collector are estimated by the cross-section SEM and EIS. The graphite coated current collector significantly reduced the interfacial resistance of the LTA battery. The second discharge capacities of bare current collector LTA and graphite coated current collector LTA batteries are 107.6 mAh/g and 148.8 mAh/g at 0.1C, respectively. The graphite coated current collector LTA batteries show higher cycle life, higher discharge capacity, and higher rate-capability than bare LTA batteries.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.672-678
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• 2019

The electrochemical properties of pitch-coated natural graphite(NG) were investigated as an anode for lithium-ion batteries. The anode materials were prepared by heat-treatment of mixture of NG and petroleum pitch at $1000^{\circ}C$. The pitches with various softening points were used as carbon precursor. The physical properties of anode materials were analyzed by TGA, SEM, PSA and BET. As the softening point increased, the thickness of the coating layer increased and the specific surface area decreased. The electrochemical performances were investigated by initial charge/discharge efficiency, cycle stability, cyclic voltammetry, rate performance and electrochemical impedance spectroscopy. The carbon-coated NG using pitch with softening points of $250^{\circ}C$ showed an initial discharge capacity of 361 mAh/g and a coulombic efficiency of 92.6%. Also, the rate performance(5 C/0.2 C) was 1.6 times higher than that of NG, and it had a capacity retention (90%) after 50 cycles at 0.5 C.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.1
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• pp.16-23
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• 2021

Lithium carbonate recovered from the waste solution generated during the lithium secondary battery manufacturing process contains heavy metals such as cobalt, nickel, and manganese. In this study, the recrystallization of lithium carbonate was performed to remove heavy metals contained in the powder and to increase the purity of lithium carbonate. First, the leaching efficiency of lithium carbonate according to pH in the aqueous hydrochloric acid solution was examined, and the effect on the recrystallization of lithium carbonate according to the equivalent and concentration of sodium carbonate was confirmed. As the equivalent and concentration of sodium carbonate increased, the recovery rate of lithium carbonate improved. And the SEM image showed that the crystal shape was changed depending on the reaction conditions with sodium carbonate. Finally, the high purity lithium carbonate of 99.9% or more was recovered by washing with water.

• Journal of the Korea Convergence Society
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• v.12 no.4
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• pp.377-387
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• 2021

This is a descriptive study to show the basis for program development to relieve depression by finding what factors influence depression of late middle-aged men. This research is the secondary analysis which was conducted with the data of 124 people and the primary data from 2018. As a result of this study, the main factors influencing depression of late middle-aged men are job stress, family bond, anxiety in later life and educational background with 70.8% of the total explanatory power. Therefore, it will be needed ways to strengthen positive coping skills for job stress & family bonds and development and application of programs to relieve depression of late middle-aged men. In addition, it is necessary to strengthen the coping skills of people who are vulnerable to depression through customized programs considering differences in educational background when developing programs.

• Korean Chemical Engineering Research
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• v.61 no.3
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• pp.348-355
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• 2023

Magnesium secondary batteries are attracting much attention due to their potential to replace conventionally used lithium ion batteries. Magnesium secondary battery cathode material Mo₆S₈ were synthesized by molten salt synthesis method and PVC as a carbon materials were added to improve electrochemical properties. Crystal structure, size and surface of the synthesized anode materials were measured through XRD and SEM. Charge-discharge profiles and rate capabilities were measured by battery test system. 2.81 wt% PVC coated sample showed the best rate capabilities of 85.8 mAh/g at 0.125 C-rate, 69.2 mAh/g at 0.5 C-rate, and 60.5 mAh/g at 1 C-rate.

• Journal of Korean Critical Care Nursing
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• v.16 no.3
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• pp.11-23
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• 2023

Purpose : This study investigates the experiences of patients in intensive care units (ICUs), and the factors influencing these experiences. Method : We used a cross-sectional survey design to analyze previously collected cohort data from 891 patients who spent over 24 hours in 19 ICUs across four university hospitals in Busan, South Korea between June 2019 and July 2020. Within a week of ICU discharge, participants completed the Korean version of the Intensive Care Experience Questionnaire, covering four areas: "awareness of surroundings," "frightening experiences," "satisfaction with care," and "recall of experiences." We used multiple linear regression to identify factors associated with the ICU experience. Results : Low income (𝛽 = -.08, p = .016), unplanned hospitalization (𝛽 = -.09, p = .006), sedation (𝛽 = -.16, p < .001), and delirium (𝛽 = -.15, p < .001) reduce patients' awareness of their surroundings. Frightening experiences are associated with being female (𝛽 = -.07, p = .027), experiencing delirium(𝛽= -.15, p<.001), and longer stays in the ICU (𝛽= -.14, p <.001). Using sedatives decreases satisfaction with care (𝛽 = -.08, p = .048). Living alone (𝛽 = -.08, p = .013) and using painkillers (𝛽 = -.08, p = .020) reduces recall of experiences. Conclusion : Negative ICU experiences are significantly associated with being female, living alone, lower income, unplanned admission, using sedatives and painkillers, delirium, and longer stays in the ICU. Thus, improving ICU experiences requires interventions that address modifiable factors, such as delirium, medication, and length of ICU stays.

• Journal of Bio-Environment Control
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• v.29 no.4
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• pp.464-472
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• 2020

We suggest a hydroponic cultivation system combined with a plasma generator to investigate the changes in the growth and functional substance content of lettuces during the cultivation period. Lettuce seedlings of uniform size were planted in semi-DFT after seeding for 3 weeks, and the plasma-activated water was intermittently operated for 1 hour at an 8 hours cycle for 4 weeks. Lettuces grew with or without plasma-activated water with the nutrient solution in hydroponics culture systems. Among the reactive oxygen species generated during plasma-activated water treatment, brown spots and necrosis appeared in the individuals closer to the plasma generating device due to O₃, and there was no significant difference in the growth parameters. While the rutin and total phenolic content of the lettuce shoot grown in the nutrient solution were higher than that of the plasma-activated water, epicatechin contents in plasma-activated water were significantly greater than the nutrient solution. However, in the roots, all kinds of secondary metabolites measured in this work, rutin, epicatechin, quercetin, and total phenolic contents, were significantly higher in the plasma-activated water than the control. These results were indicated that the growth of lettuce was decreased due to the reactive oxygen species such as ozone in the plasma-activated water, but the secondary metabolites in the root zone increased significantly. It has needed to use this technology for the cultivation of root vegetables with the modified plasma-activated water systems to increase secondary metabolite in the roots.