• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.46.3-47
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• 2020

Variations in the brightness of asteroids are caused by their spins, irregular shapes and companions. Thus, in principle, the spin state and shape model of a single object or, a combined model of spins, shapes and mutual orbit of a multiple components can be constructed from the analysis of light curves obtained from the time-series photometry. Using ground- and space-based facilities, a number of time-series photometric observations of asteroids have been conducted to find the possible causes of their light variations. Nonetheless, only about 2% of the known asteroids have been confirmed for their rotation periods. Therefore, a follow-on systematic photometric survey of asteroids is essential. We started an asteroid light curve survey for this purpose using Korea Microlensing Telescope Network (KMTNet) during 199 nights between the second half of 2019 and the first half of 2020. We monitored within a 2° × 14° region of the sky per each night with 25 min cadences. In order to observe as many asteroids as possible with a single exposure, we mostly focus on the ecliptic plane. In our survey, 25,925 asteroids were observed and about 8,000 of them were confirmed for their rotation periods. In addition, using KMTNet's 24-hour continuous monitoring, we collected many composite light curves of slow rotating asteroids that were rarely obtained with previous observations. In this presentation, we will introduce the typical light curves of asteroids obtained from our survey and present a statistical analysis of spin states and shapes of the asteroids from this study.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.317-318
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• 2023

This study is part of the carbonation degree DB accumulation through quantitative analysis of carbonation depth, Ca(OH)₂ and CO₂ according to the type of finish and years of use of old concrete structures in order to predict the amount of CO₂ that can be absorbed through carbonation of concrete. To this end, the depth of carbonation of the concrete core specimen is measured using an indicator, and the dry amount of water combined with CO₂ in the sample is measured using a differential thermal gravimetric analyzer for samples in the carbonation area and non-carbonated area classified by the indicator, and the absorption compared to the weight of the sample. The amount of absorbed CO₂ was calculated. In addition, the degree of carbonation was calculated through quantitative comparison of Ca(OH)₂ in the carbonation section and non-carbonation section. In the future, we will continue to add the survey and analysis data of dismantled structures and use them as basic data for estimating the amount of carbon dioxide that can be absorbed according to the exposure conditions and years of use by concrete mix.

• Journal of Preventive Medicine and Public Health
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• v.57 no.1
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• pp.18-27
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• 2024

Objectives: This study investigated the association between exacerbated economic hardship during the coronavirus disease 2019 (COVID-19) pandemic and changes in the health behaviors of Korean adolescents. Methods: We analyzed data from the 2021 Korea Youth Risk Behavior Survey and included 44 908 students (22 823 boys and 22 085 girls) as study subjects. The dependent variables included changes in health behaviors (breakfast habits, physical activity, and alcohol use) that occurred during the COVID-19 pandemic. The aggravation of economic hardship by COVID-19 and the subjective economic status of the family were used as exposure variables. Multiple logistic regression analysis was utilized to calculate the prevalence odds ratios (PORs). Results: Severe exacerbation of a family's economic hardship due to COVID-19 was negatively associated with the health behaviors of adolescents, including increased breakfast skipping (POR, 1.85; 95% confidence interval [CI], 1.55 to 2.21 for boys and POR, 1.56; 95% CI, 1.27 to 1.92 for girls) and decreased physical activity (POR, 1.37; 95% CI, 1.19 to 1.57 for boys and POR, 1.38; 95% CI, 1.19 to 1.60 for girls). These negative changes in health behaviors were further amplified when combined with a low subjective family economic status. Conclusions: The experience of worsening household hardship can lead to negative changes in health behavior among adolescents. It is crucial to implement measures that address the economic challenges that arise from stressful events such as COVID-19 and to strive to improve the lifestyles of adolescents under such circumstances.

• Journal of the Korean Wood Science and Technology
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• v.52 no.2
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• pp.145-156
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• 2024

Unlike resistant cells, persister cells resist antibiotics due to a decreased cellular metabolic rate and can transition back to normal susceptible cells when the antibiotic is removed. These persister cells contribute to the chronic symptoms of infectious diseases and promote the emergence of resistant strains with continuous antibiotic exposure. Therefore, eliminating persister cells represents a promising approach to significantly enhance antibiotic efficacy. Here, we found that Coicis Semen extract reduced Staphylococcus aureus persister cells at a concentration of 0.5 g/L. Linoleic acid and oleic acid, the major components of Coicis Semen extract, exhibited a comparable reduction in persister cells when combined with three antibiotics: ciprofloxacin, oxacillin, and tobramycin. Conversely, these effects were nullified in the presence of the surfactant Tween 80 (1%), suggesting that the hydrophobic characteristics of linoleic acid and oleic acids play a pivotal role in reducing the number of S. aureus persister cells. Considering the concentration-dependent effects of linoleic acid and oleic acid, the persister-reducing activity of Coicis Semen extract was primarily attributed to these fatty acids. Moreover, Coicis Semen extract, linoleic acid, and oleic acid increased the cell membrane permeability of S. aureus. Interestingly, this effect was counteracted by 1% Tween 80, indicating a close association between the reduction of persister cells and the increase in cell membrane permeability. The identified compounds could thus be used to eliminate persister cells, thereby enhancing therapeutic efficacy and shortening treatment duration. When used in conjunction with antibiotics, they may also mitigate chronic symptoms and significantly reduce the emergence of antibiotic-resistant bacteria.

• Hip & pelvis
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• v.36 no.1
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• pp.26-36
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• 2024

Total hip arthroplasty (THA) is a frequently performed procedure; the objective is restoration of native hip biomechanics and achieving functional range of motion (ROM) through precise positioning of the prosthetic components. Advanced three-dimensional (3D) imaging and computed tomography (CT)-based navigation are valuable tools in both the preoperative planning and intraoperative execution. The aim of this study is to provide a thorough overview on the applications of CT scans in both the preoperative and intraoperative settings of primary THA. Preoperative planning using CT-based 3D imaging enables greater accuracy in prediction of implant sizes, leading to enhancement of surgical workflow with optimization of implant inventory. Surgeons can perform a more thorough assessment of posterior and anterior acetabular wall coverage, acetabular osteophytes, anatomical landmarks, and thus achieve more functional implant positioning. Intraoperative CT-based navigation can facilitate precise execution of the preoperative plan, to attain optimal positioning of the prosthetic components to avoid impingement. Medial reaming can be minimized preserving native bone stock, which can enable restoration of femoral, acetabular, and combined offsets. In addition, it is associated with greater accuracy in leg length adjustment, a critical factor in patients' postoperative satisfaction. Despite the higher costs and radiation exposure, which currently limits its widespread adoption, it offers many benefits, and the increasing interest in robotic surgery has facilitated its integration into routine practice. Conducting additional research on ultra-low-dose CT scans and examining the potential for translation of 3D imaging into improved clinical outcomes will be necessary to warrant its expanded application.

• Steel and Composite Structures
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• v.52 no.6
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• pp.627-645
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• 2024

Punching shear is a brittle failure that occurs within the RC flat slabs where stresses are concentrated within small regions, resulting in a catastrophic and unfavorable progressive collapse. However, increasing the slab slenderness ratio is believed to significantly affect the slab's behavior by the induced strain values throughout the slab depth. This study examines the punching shear behavior of flat slabs by the nonlinear finite element analysis approach using ABAQUS software, where 72 models were investigated. The parametric study includes the effect of opening existence, opening-to-column ratio (O/C), temperature level, slenderness ratio (L/d), and flexural reinforcement rebar diameter. The behavior of the punching shear failure was fully examined under elevated temperatures which was not previously considered in detail along with the combined effect of the other sensitive parameters (opening size, slab slenderness, and reinforcement rebar size). It has been realized that increasing the slab slenderness has a major role in affecting the slab's structural behavior, besides the effect of the flexural reinforcement ratio. Reducing the slab's slenderness from 18.27 to 5.37 increased the cracking load by seven times for the slab without openings compared to nine times for the initial stiffness value. In addition, the toughness capacity is reduced up to 80% upon creating an opening, where the percentage is further increased by increasing the opening size by about an additional 10%. Finally, the ultimate deflection capacity of flat slabs with an opening is increased compared to the solid slab with the enhancement being increased for openings of larger size, larger depths, and higher exposure temperature.

• Journal of Veterinary Clinics
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• v.24 no.2
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• pp.99-103
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• 2007

The antibacterial efficacy of 0.1% (w/v) chitosan solution against Staphylococcus intermedius isolated from a dog with superficial pyoderma was evaluated in vitro and in vivo. The exposure time for the 0.1% chitosan solutions at different pH to be able to eliminate the bacterial cells and the effect of pH of the solutions on antibacterial activity was tested at the same time in vitro. The antibacterial activity of chitosan was compared to other antibacterial agents including 2.5% benzoyl peroxide, 0.5% chlorhexidine acetate, 0.1% chitosan solution combined with 2.5% benzoyl peroxide and chitosan combined with 0.5% chlorhexidine using a modified detergent scrub quantitative technique in 10 adult mongrel dogs in vivo. They were able to eliminate a number of bacteria after the exposure time of 10 minutes at varying degrees according to the pH of the solutions. The antibacterial activity of chitosan was inversely affected by pH with higher activity at lower pH value. The 0.1% chitosan solution was also efficacious against Staphylococcus intermedius in vivo. The combinations of chitosan with benzoyl peroxide and with chlorhexidine were shown to exert higher activity when compared to those of chitosan alone and benzoyl peroxide or chlorhexidine alone. The 0.1% chitosan solution was considered to be efficacious against Staphylococcus intermedius isolated from a dog with superficial pyoderma in both in vivo and in vitro and have a potential for the clinical applications in the treatment or pyoderma in dogs.

• Journal of the Korean Society of Radiology
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• v.8 no.4
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• pp.181-187
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• 2014

The purpose of this study were to analyze the characteristic of the glow curves in order to the glow temperature of the thermoluminescent dosimeters (TLDs) for the absorbed dose measurement of the radiation therapy. In this study, we was used the TLDs of the LiF:Mg${\cdot}$Ti, LiF:Mg${\cdot}$Cu${\cdot}$P, $CaF_2$:Dy, $CaF_2$:Mn (Thermo Fisher Scientific Inc., USA). The source-to-solid dry phantom (RW3 slab, IBA Dosmetry, Germany) surface distance was set at 100 cm, and the exposure dose of 100 MU (monitor unit) was used 6- and 15-MV X-rays, and 6- and 12-MeV electron beams in the reference depth, respectively. After the radiations exposure, we were to analyze the glow curves by using the TL reader (Hashaw 3500, Thermo Fisher Scientific Inc., USA) at the fixed heating rate of $15^{\circ}C/sec$ from $50^{\circ}C$ to $260^{\circ}C$. The glow peaks, the trapping level in the captured electrons and holes combined with the emitted light, were discovered the two or three peak. When the definite increasing the temperature of the TLDs, the maximum glow peak representing the glow temperature was follow as; $LiF:Mg{\cdot}Ti$: $185.5{\pm}1.3^{\circ}C$, $LiF:Mg{\cdot}Ti$: $135.0{\pm}5.1^{\circ}C$, $CaF_2$:Dy: $144.0{\pm}1.6^{\circ}C$, $CaF_2$:Mn: $294.3{\pm}3.8^{\circ}C$, respectively. Because the glow emission probability of the captured electrons depend on the heating temperature after the exposure radiation, TLDs by applying the fixed heating rate, the accuracy of measurement will be able to improve within the absorbed dose measurement of the radiation therapy.

• Journal of Environmental Health Sciences
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• v.46 no.3
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• pp.312-323
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• 2020

Objective: This study aimed to summarize the physiochemical properties, toxicity, and legal regulation of chloromethylisothiazolinone (CMIT) and/or methylisothiazolinone (MIT), review the health effects caused by exposure to CMIT/MIT, and evaluate the individual association of lung injury with the use of humidifier disinfectants (HD) containing a mixture of CMIT and MIT. Method: A literature review was conducted by searching keywords such as CMIT, MIT, health effect, dermatitis, asthma, and lung injury, either singly or combined. Results: Both CMIT and/or MIT were found to be associated with the development of several types of adverse health effects. In particular, respiratory diseases including asthma, nasal symptoms, cough, and rhinitis were caused by the use of products including CMIT or/and MIT. The mixture of CMIT/MIT has been banned in cosmetics. As of the end of 2017, nine patients who were confirmed to have HD associated lung injury (HDLI) were found to have used only an HD brand containing CMIT and MIT. Their responses regarding the name of the HD used could be trustworthy based on the short duration of HD use (less than six months) before the onset of HDLI and frequent use of HD per day. Conclusion: According to the toxicity and HDLI cases, the use of HD containing CMIT and /or MIT can cause fatal lung injury. Further study with manufacturers' assistance is necessary in order to obtain more clear evidence on the causal relationship since HDLI cases are being reported continuously.

• Journal of Environmental Health Sciences
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• v.41 no.5
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• pp.289-298
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• 2015

Objectives: The method of analyzing urinary arsenic by flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS) is generally used because it shows relatively greater sensitivity, low detection limits, low blocking action, and is simple to operate. In this study, the results of analysis according to three pre-reductants commonly used in the FI-HG-AAS method were compared with each other. Methods: To analyze urinary arsenic, nineteen urine samples were collected from adults aged 43-79 years old without occupational arsenic exposure. Analysis equipment was FI-HG-AAS (AAnalyst 800/FIAS 400, Perkin- Elmer Inc., USA). The three pre-reductants were potassium iodide (KI/AA), C3H7NO2S (L-cysteine), and a mixture of KI/AA and L-cysteine (KI/AA&L-cysteine). Results: In the results of the analysis, the recovery rate of the method using KI/AA was 82.3%, 95.7% for Lcysteine, and 123.5% for KI/AA and L-cysteine combined. When compared with the results by use of high performance liquid chromatography inductively-coupled plasma mass spectrometry (HPLC-ICP-MS), the method using L-cysteine was the closest to those using HPLC-ICP-MS ($98.57{\mu}g/L$ for HPLC-ICP-MS; $74.96{\mu}g/L$ for L-cysteine; $69.23{\mu}g/L$ for KI/AA and L-cysteine; $13.06{\mu}g/L$ for KI/AA) and were significantly correlated (R2=0.882). In addition, they showed the lowest coefficient of variation in the results between two laboratories that applied the same method. Conclusion: The efficiency of hydride generation is considered highly important to the analysis of urinary arsenic via FI-HG-AAS. This study suggests that using L-cysteine as a pre-reductant may be suitable and the most rational among the FI-Hg-AAS methods using pre-reductants.