• Korean Journal of Optics and Photonics
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• v.9 no.1
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• pp.15-19
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• 1998

We have present an all-optical technique to significantly reduce the dispersion penalty of a spectrum-sliced channel in high-speed and long-distance transmissions. We have reduced the necessary optical bandwidth for the 2.5 Gb/s incoherent light transmission down to 0.1 nm by expanding the optical bandwidth of a received signal. The optical bandwidth expansion was realized using the intra-channel fiber four-wave mixing at the receiver resulting in an improvement of th signal-to-noise ratio of the received light channel. We have successfully demonstrated the transmission of a 2.5 Gb/s NRZ signal with the 0.1 nm bandwidth over a 300 km dispersion-shifted fiber. An error floor occurs at $1{\times}10^{-5}$ BER without the optical bandwidth expansion. With the optical bandwidth expansion, however, the error floor decreases to less than $1{\times}10^{-10}$. The transmission penalty was less than 0.5 dB at $1{\times}10^{-10}$ BER. To our knowledge, the optical bandwidth of 0.1 nm used in our experiment is the narrowest optical bandwidth reported so far.

• Transactions of Materials Processing
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• v.30 no.6
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• pp.291-300
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• 2021

Currently, starting with electric vehicles, the application of ultra-high-strength steel sheets and light metals has expanded to improve mileage by reducing vehicle weight. At a time when internal combustion engine vehicles are rapidly changing to electric vehicles, the application of ultra-high-strength steel is expanding to satisfy both weight reductions and the performance safety of the chassis parts. There is an urgent need to improve the quality of parts without defects. It is particularly difficult to estimate the part formability through the finite element method (FEM) in the burring operation, so product design has been based on the hole expansion ratio (HER) and experience. In this study, design of experiment (DOE), analysis of variance (ANOVA), and regression analysis were combined to optimize the formability by adjusting the process variables affecting the burring formability of ultra-high-strength steel parts. The optimal variables were derived by analyzing the influence of variables and the correlation between the variables through FE analysis. Finally, the optimized process parameters were verified by comparing experiment with simulation. As for the main influence of each process variable, the initial hole diameter of the piercing process and the shape height of the preforming process had the greatest effects on burring formability, while the effect of a lower round of punching in the burring process was the least. Moreover, as the diameter of the initial hole increased, the thickness reduction rate in the burring part decreased, and the final burring height increased as the shape height during preforming increased.

• Neonatal Medicine
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• v.28 no.3
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• pp.124-132
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• 2021

Purpose: Neonatal near miss (NNM) allows for the detection of risk factors associated with serious newborn complications and death, the prevention of which could reduce neonatal mortality. This study was conducted with the objective of identifying predictors for NNM in a tertiary hospital in Bangalore city. Methods: This was an unmatched case-control study involving 120 NNM cases and 120 controls. NNM was determined using Pileggi-Castro's pragmatic and management criteria. Data was collected from in-patient hospital records and interviews of postpartum mothers. Multiple logistic regression of exposure variables was performed to calculate adjusted odds ratio (AOR) with 95% confidence interval (CI). Results: Significant predictors were maternal age ≥30 years (AOR, 5.32; 95% CI, 1.12 to 9.29; P=0.041), inadequate antenatal care (ANC) (AOR, 8.35; 95% CI, 1.98 to 51.12; P=0.032), <3 ultrasound scans during pregnancy (AOR, 12.5; 95% CI, 1.60 to 97.27; P=0.016), maternal anaemia (AOR, 18.96; 95% CI, 3.10 to 116.02; P=0.001), and any one obstetric complication (hypertensive disorder in pregnancy, diabetes in pregnancy, preterm premature rupture of membranes, prolonged labour, obstructed labour, malpresentation) (AOR, 4.34; 95% CI, 1.26 to 14.95; P=0.02). Conclusion: The predictors of NNM identified has important implications for public health policy and practice whose modifications can improve NNM. These include expanding essential ANC package to include ultrasound scans, ensuring World Health Organization recommendations of eight ANC visits, capacity building at all levels of health care to strengthen routine ANC and obstetric care for effective screening, referral and management of obstetric complications.

• Archives of Craniofacial Surgery
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• v.23 no.5
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• pp.205-210
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• 2022

Background: Nasal bone fractures are the most common type of facial bone fracture, but are under-studied in adults above 65 years of age. Therefore, we investigated the epidemiology and patterns of nasal bone fractures among older adults in comparison to different age groups. Methods: This retrospective study included 2,321 nasal bone fracture patients who underwent surgery at our hospital from January 2010 to December 2017. The patients were classified by age as preschoolers, school-age children, young and middle-aged adults, and the elderly. We performed pairwise comparisons between elderly patients and each other age group in terms of sex, cause of injury, and fracture type. Results: The 2,321 nasal bone fracture patients included 76 elderly patients (50 men [65.8%] and 26 women [34.2%]). In these patients, the two most common injury causes were falling or slipping down (n= 39; 51.3%) and road traffic accidents (n= 19; 25.0%). According to the Stranc and Robertson classification, the most common force vector was lateral, and plane 2 fractures with lateral forces predominated. Conclusion: The elderly showed similar patterns of nasal bone fractures to those observed in young and middle-aged adults, but significant differences from preschoolers (in the injury vector and plane of fracture) and from school-age children (in the sex ratio and plane of fracture). However, elderly patients presented significantly different epidemiological characteristics compared to the other three groups. Therefore, it is necessary to improve the quality of life of the elderly and prepare for the upcoming super-aged society by taking steps to reduce the incidence and severity of fractures. Possible options for doing so include strengthening individual-level safety factors and expanding the social safety net for the elderly.

• The Journal of the Convergence on Culture Technology
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• v.8 no.2
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• pp.349-354
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• 2022

This research was conducted in order to improve the hydrolysis resistance and mechanical properties of a resin compound and biodegradable mulching film, produced through the use of PBAT(Poly Butylene Adipate-co-Terephthalate) and PLA(Poly Lactic Acid). Various ratios of chain extenders and mechanical properties according to the annealing temperature conditions were investigated. The annealing process showed that compound resin can improve the crystallization capacity. In addition, incorporation of the chain extender was shown to improve and increase the tensile strength and hydrolysis resistance of the film. In the case of 0.6phr chain extender, the tensile strength was 383.0Kgf/cm², which was improved by 155% compared to the control films. When the blow up ratio(BUR) was 2.5, the optimal tensile strength of the film increased greatly, expanding up to 379.0/195.2kgf/cm² in the both machine direction (MD) and transverse direction (TD).

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.4
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• pp.78-96
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• 2023

Urban traffic information is collected by various systems such as VDS, DSRC, and radar. Recently, with the development of deep learning technology, smart intersection systems are expanding, are more widely distributed, and it is possible to collect a variety of information such as traffic volume, and vehicle type and speed. However, as a result of reviewing related literature, the performance evaluation criteria so far are rbs-based evaluation systems that do not consider the deep learning area, and only consider the percent error of 'reference value-measured value'. Therefore, a new performance evaluation method is needed. Therefore, in this study, individual error, interval error, and overall error are calculated by using a formula that considers deep learning performance indicators such as precision and recall based on data ratio and weight. As a result, error rates for measurement value 1 were 3.99 and 3.54, and rates for measurement value 2 were 5.34 and 5.07.

• International Journal of Advanced Culture Technology
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• v.11 no.3
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• pp.260-267
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• 2023

We aimed to investigate the proportions of MTB- and NTM-positive tests and the distribution patterns of species isolated by contracted testing agencies in South Korea. Respiratory specimens submitted to contracted testing agencies in South Korea for AFB culture from January 2014 to December 2021 were included (533,713 specimens in total). Trends based on MTB and NTM detection, patient sex and age, culture medium type, and testing year were analyzed. MTB and NTM positive detection increased in the patients. The average ages of MTB- and NTM-positive patients increased in those aged ≥61 years. For solid culture, the MTB detection rate decreased from 5.9% in 2014 to 3.3% in 2018 and increased to 4.7% in 2021; the NTM detection rate increased from 2.1% in 2014 to 3.4% in 2018 and 3.7% in 2021. For liquid culture, the MTB detection rate decreased from 8.3% in 2014 to 5.5% in 2018 and increased to 6.0% in 2021; the NTM detection rate increased from 3.5% in 2014 to 5.5% in 2018 and decreased to 5.3% in 2021. An isolation ratio reversal between MTB and NTM was observed in 2018. In this study, we provide information on mycobacterial isolation rates and species distributions using AFB culture test results from Korea's referral laboratories. Increased MTB- and NTM-isolation rates were observed in individuals aged ≥60 years, indicating the need for regular testing and focused management for them. Expanding liquid culture applications, which show higher positivity rates than solid culture methods, is necessary.

• Journal of Korea Society of Industrial Information Systems
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• v.14 no.2
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• pp.16-22
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• 2009

The most efficient method to reduce duplicated messages is a partial dominant pruning for receiving and forwarding messages by in-fly format on the mobile ad hoc network. In this paper, we propose directional partial dominant pruning method by expanding partial dominant pruning for reducing not only number of forwarding nodes but number of antenna elements on the ad hoc network with directional antennas. by simulation, we prove superiority that average number of forwarding nodes for each antenna element and the ratio of duplicated messages for each nodes rather than existing partial dominant pruning method though the number of antenna elements are increasing rather than in case of using omni antennas.

• Journal of The Korean Society of Integrative Medicine
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• v.11 no.3
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• pp.11-23
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• 2023

Purpose : The stress of job-seeking college students is gradually worsening due to the continuing recession in the job market. Therefore, this study aims to verify whether intervention with an 'aromatherapy education program,' which combines theory and practice, has greater effect on stress, self-efficacy, and autonomic nervous system function than simple inhalation of essential oils in female college students preparing for employment. Methods : A single-blind, randomized controlled trial was conducted once a week for a total of 4 weeks with 29 female college students preparing for employment. Interventions included essential oil inhalation combined with an aromatherapy education program (experimental group(EG), n=14) and essential oil inhalation alone (control group(CG), n=15); measurements were taken before, immediately after, and 2 weeks after completion of the intervention. Evaluations were conducted using the job-seeking stress scale, stress VAS, self-efficacy scale, and a pulse-wave measuring instrument. Results : There were significant differences between the CG and EG groups with repeated measurements of job-seeking stress (p=.003), cognitive stress (p<.001), and self-efficacy (p<.001). There was a significant interaction between group and time. There were also significant differences between the CG and EG in terms of autonomic nervous system changes stress index(p=.047), total power(p=.029), high frequency(p=.036), and low frequency/high frequency ratio(p=.049). However, there was no significant difference in low frequency between the groups. Conclusion : The aromatherapy education program was more effective in improving job-seeking stress, cognitive stress, self-efficacy, and autonomic nervous system function than simple essential oil inhalation. For the aromatherapy education program to be useful as a complementary intervention for stress management in job seekers, it will be necessary to gather additional evidence of its efficacy by conducting follow-up studies with diverse participants and expanding the numbers, and durations, of the interventions.

• Journal of Environmental Health Sciences
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• v.49 no.5
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• pp.275-288
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• 2023

Background: When basic local governments want to improve their air quality management policies, they need fundamental evidence, such as the effectiveness of current policies or scenario results. Objectives: The purpose of this study is to lay the groundwork for a process to calculate air pollutant reduction from basic local government air quality policies and provide numerical estimates of PM_2.5 concentrations following improved policies. Methods: We calculated the amount of air pollutant reduction that can be expected in the research region based on the Gyeonggi-do Air Environment Management Implementation Plan issued in 2021 and guidelines from the Korean Ministry of Environment. The PM_2.5 concentration variations were numerically simulated using the CMAQ (photochemical air quality model). Results: The research regions selected were Suwon, Ansan, Yongin, Pyeongtaek, and Hwaseong in consideration of population, air pollutant emissions, and geographical requirements. The expected reduction ratios in 2024 compared to 2018 are CO (3.0%), NO_x (7.9%), VOCs (0.7%), SO_x (0.1%), PM₁₀ (2.4%), PM_2.5 (6.1%), NH₃ (0.05%). The reduced PM_2.5 concentration ratio was highest in July and lowest in April. The expected concentration reduction of yearly mean PM_2.5 in the research region is 0.12 ㎍/m³ (0.6%). Conclusions: Gyeonggi-do is now able to quickly provide air pollutant emission reduction calculations by respective policy scenario and PM_2.5 simulation results, including for secondary aerosol particles. In order to provide more generalized results to basic local governments, it is necessary to conduct additional research by expanding the analysis tools and periods.