• Ocean and Polar Research
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• v.43 no.1
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• pp.1-14
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• 2021

In this study, extreme wind speeds in the Western North Pacific (WNP) were estimated using reanalysis wind fields synthesized with an empirical typhoon vortex model. Reanalysis wind data used is the Fifth-generation European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA5) data, which was deemed to be the most suitable for extreme value analysis in this study. The empirical typhoon vortex model used has the advantage of being able to realistically reproduce the asymmetric winds of a typhoon by using the gale/storm-forced wind radii information in the 4 quadrants of a typhoon. Using a total of 39 years of the synthesized reanalysis wind fields in the WNP, extreme value analysis is applied to the General Pareto Distribution (GPD) model based on the Peak-Over-Threshold (POT) method, which can be used effectively in case of insufficient data. The results showed that the extreme analysis using the synthesized wind data significantly improved the tendency to underestimate the extreme wind speeds compared to using only reanalysis wind data. Considering the difficulty of obtaining long-term observational wind data at sea, the result of the synthesized wind field and extreme value analysis developed in this study can be used as basic data for the design of offshore structures.

• Journal of The Korean Astronomical Society
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• v.55 no.4
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• pp.131-138
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• 2022

We report the discovery of four quasars with M₁₄₅₀ ≳ -25.0 mag at z ~ 5 and supermassive black hole mass measurement for one of the quasars. They were selected as promising high-redshift quasar candidates via deep learning and Bayesian information criterion, which are expected to be effective in discriminating quasars from the late-type stars and high-redshift galaxies. The candidates were observed by the Double Spectrograph on the Palomar 200-inch Hale Telescope. They show clear Lyα breaks at about 7000-8000 Å, indicating they are quasars at 4.7 < z < 5.6. For HSC J233107-001014, we measure the mass of its supermassive black hole (SMBH) using its C _IV λ1549 emission line. The SMBH mass and Eddington ratio of the quasar are found to be ~10⁸ M_⊙ and ~0.6, respectively. This suggests that this quasar possibly harbors a fast growing SMBH near the Eddington limit despite its faintness (L_Bol < 10⁴⁶ erg s^-1). Our 100% quasar identification rate supports high efficiency of our deep learning and Bayesian information criterion selection method, which can be applied to future surveys to increase high-redshift quasar sample.

• Publications of The Korean Astronomical Society
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• v.38 no.2
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• pp.91-98
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• 2023

We present a novel method that can enhance the detection success rate of interstellar objects. Interstellar objects are objects that are not gravitationally bound to our solar system and thus are believed to have originated from other planetary systems. Since the finding of two interstellar objects, 1l/'Oumuamua in 2017 and 2l/Borisov in 2019, much attention has been paid to finding new interstellar objects. In this paper, we propose the use of Heliospheric Imagers (HIs) for the survey of interstellar objects. In particular, we show HI data taken from Solar TErrestrial RElation Observatory/Sun Earth Connection Coronal and Heliospheric Investigation and demonstrate their ability to detect 'Oumuamua-like interstellar objects. HIs are designed to monitor and study space weather by observing the solar wind traveling through interplanetary space. HIs provide the day-side observations and thus it can dramatically enlarge the observable sky range when combined with the traditional night-side observations. In this paper, we first review previous methods for detecting interstellar objects and demonstrate that HIs can be used for the survey of interstellar objects.

• Atmosphere
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• v.33 no.1
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• pp.33-47
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• 2023

In this study, for the application of observation errors to the Korean Integrated Model (KIM) to utilize the Constellation Observing System for Meteorology, Ionosphere & Climate-2 (COSMIC-2) new satellites, the observation errors were diagnosed based on the Desroziers method using the cost function in the process of variational data assimilation. We calculated observation errors for all observational species being utilized for KIM and compared with their relative values. The observation error of the calculated the Global Navigation Satellite System Radio Occultation (GNSS RO) was about six times smaller than that of other satellites. In order to balance with other satellites, we conducted two experiments in which the GNSS RO data expanded by about twice the observation error. The performance of the analysis field was significantly improved in the tropics, where the COSMIC-2 data are more available, and in the Southern Hemisphere, where the influence of GNSS RO data is significantly greater. In particular, the prediction performance of the Southern Hemisphere was improved by doubling the observation error in global region, rather than doubling the COSMIC-2 data only in areas with high density, which seems to have been balanced with other observations.

• Safety and Health at Work
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• v.14 no.1
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• pp.1-9
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• 2023

Background: Firefighting involves exposure of firefighters to risks related to this activity, serious injuries, and occupational diseases are recorded. There are other consequences such as thermal and emotional stress. This systematic review is proposed in order to analyze the risks and consequences faced by these workers and thus provide elements to improve safety management systems in institutions. Method: A descriptive observational study of systematic literature review on the risks and consequences of exposure to firefighters' activity was proposed, and the information was analyzed and described based on the available data and according to the variables determined. Results: The studies showed data on mechanical, physical, chemical, psychosocial risks, workers' perception and resilience, and epidemiological data. Information related to firefighters' activity on falls and slips, exposure to noise, and high concentrations of carbon monoxide is detailed. In addition, the relationship between burnout, cognitive, and physical fatigue as adverse effects on health and performance is mentioned. Conclusions: Among the preventive measures, the use of personal protective equipment is suggested, incorporation in prevention programs of information on exposure to risk factors, as well as the implementation of models that can predict the perception of workers, additionally, the generation of management systems with safety climate models for fire departments.

• Journal of the Korea Safety Management & Science
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• v.25 no.2
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• pp.107-111
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• 2023

This study aims to empirically investigate effects of motion repetition and external load according to joint motion on discomfort through an experiment. Eighteen college students (female: 9; male: 9) participated in an experiment measuring perceived discomfort using the Borg CR10. Joint(wrist, elbow, shoulder and trunk) motion, its repetition and external load were adopted as independent variables. The results showed that all three independent variables were statistically significant on discomfort. Participants' sex also significantly affected discomfort obtained in the experiment. While the interactions of joint motion and repetition, and joint motion and external load were not significant at α = 0.05, that of motion repetition and external load was significant. Based on the experimental results, four regression equations by the joints involved were presented, which could be used as a tool for evaluating postural loads by the joints. It may be postulated that based on the results of this study, scoring systems of RULA and REBA, and those of OWAS and REBA underestimates effects of motion repetition and external load, respectively. It is expected that the results of this study will be used as a basic data for developing an observational method properly reflecting the effects of motion repetition and external load.

• Safety and Health at Work
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• v.15 no.1
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• pp.102-109
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• 2024

Background: In today's modern world, longer working hours, shift work, and working at night have become major causes of the disruption of our natural circadian rhythms. This study aimed to investigate the effects of the type of shift work (rotating vs. fixed day), duty period (on-duty vs. off-duty), and working period within each shift (nighttime vs. daytime) on the circadian rhythm characteristics of nurses who provide direct patient care. Methods: This cross-sectional study used a purposive sampling method. Cosinor analysis was applied to analyze the actigraphy data of nurses providing direct patient care for seven consecutive days. The linear mixed effects model was then used to determine any variances between shift type, duty period, and working period within each shift for the nurses. Results: The mesor value did not differ according to nurses' shift type, duty period, and working period within each shift. The amplitude was statistically higher in on-duty nurses and in daytime working hours. The acrophase was significantly delayed in nighttime working hours. As well as nurses in rotating shift had experience. Conclusion: Our findings revealed that the peak activity of nurses occurs significantly later at night while working and nurses working during nighttime hours may have a weaker or less distinct circadian rhythm. Thus, this study suggests that limits be placed on the number of rotating nighttime shifts for nurses.

• Journal of Preventive Medicine and Public Health
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• v.57 no.4
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• pp.399-406
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• 2024

Objectives: This study developed a causal relationship model of herb use from observational data and analyzed the direct and indirect effects of herb use on health according to the model. Methods: A cross-sectional study was conducted with 400 participants aged 26-59 years, selected through multistage random sampling. The instruments used for data collection included demographic information, herb use, health literacy (HL), perceived social support, societal values, and attitudes toward herb use. The conceptual model, hypothesized based on prior evidence, was tested using confirmatory factor analysis through structural equation modeling. Path coefficients were estimated using the maximum likelihood method. Results: The final model utilized empirical data, which showed that perceived social support had the most significant impact on herb use. This was followed by HL, positive attitudes toward herbal remedies, and societal values, with coefficients of 0.31, 0.18, and 0.16, respectively. When analyzing variables that indirectly affected herb use, it was clear that positive attitudes, perceived social support, and societal values significantly influenced herb use through HL, with influence coefficients of 0.08, 0.16, and 0.04, respectively. Together, these variables accounted for 68% of the variance in herb use. Conclusions: The findings from this study can be utilized to develop and implement strategies that guide the use of herbal products, ultimately aiming to improve human health.

• Journal of Society of Preventive Korean Medicine
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• v.28 no.2
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• pp.19-29
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• 2024

Objective : Pattern identification in Korean Medicine is a core value, leading to a quantitative and qualitative increase in related studies. This study aims to identify trends in newly published research and discuss pattern identification. Method : We reviewed studies from 2015 to 2023 using the Oriental Medicine Advanced Searching Integrated System provided by the Korea Institute of Oriental Medicine. The keywords used were: pattern identification, cold-heat, deficiency-excess, exterior-interior, yin-yang, phlegm-retained fluid, static blood, qi-blood, qi deficiency, blood deficiency, yin deficiency, yang deficiency, and four-constitution. Results : A total of 150 studies met the inclusion criteria. These comprised 84 observational studies, including case reports, 2 experimental studies, and 64 literature reviews. Most studies were published in the Korean Journal of Oriental Physiology and Pathology. On average, 17.1 studies were published annually, although the number of studies has decreased over the years. Network analysis revealed that the main keyword in titles was pattern identification (n=122), followed by study (n=68) and patients (n=34). Conclusion : These findings highlight trends in studies related to pattern identification, with a focus on its standardization. Considering the limitations of pattern identification, a shift towards a disease-centered approach is recommended.

• Magazine of the Korean Society of Agricultural Engineers
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• v.32 no.3
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• pp.31-38
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• 1990

The power water flowed out from the multipurpose darn influences the ecosystem approximately because of the low water temperature. An appropriate counter measure to the rising water temperature is needed for growing crops especially when the temperature is below 18˚C in the source of the irrigation water This observational study is practiced in Yong-Doo water warming canal and pond in the down stream of Choong-Ju multipurpose dam and is practiced for analyse and compare the rising effects in actural water temperature by actual measurement with the rising effects of planned water temperatuer by the basic theoritical method and for the help to present the direction in plan establishment through investigate the results afterwards. The results are as follows. 1.The degree of the rise of the water temperature can be decided by $\theta$x=$\theta$o +K L--v.h (T-$\theta$˚)Then, K values of a factor representing the characteristics of the water warming canal were 0.00002043 for the type I. and 0.0000173 for the type II. respectively. 2.A variation of water temperature which produced by the difference effective temperature and water temperature in the water warming canal was $\theta$x1 = 16.5 + 15.9(1-e -0.00018x), $\theta$x2 =18.8 + 8.4( 1-e -0.000298x)for the type I. and $\theta$x, = 19.6 + 12.8 ( 1-e -0.00041x) for the type II. 3.It was shown that the effects of the rise of water temperature for the type I. water warming canal were greater than that of type II. as a resultes of broadening the surface of the canal compared with the depth of water, coloring the surface of water canal and installing the resistance block. 4.In case of the type I. water warming canal, the equation between the air temperature and the degree of the rise of water temprature could be made ;Y= 0.4134X + 7.728 In addition, in case of the type II. water warming canal, the correlation was very low. 5.A monthly variation of the water temperature in the water warming canal was the highest in August during the irrigation period and the water temperature rose with the air temperature until August. However, it was blunted after then. 6.A rising degree of water temperature of the practical value in the water warming pond was higher than that of the theoritical equation by 69% for the type I. and 57% for the type II. Accordingly, it was possible to acquire the result near the practical value.$\theta$w-$\theta$o=[1-exp{ -h(1+2$\psi$) . X($\theta$w-$\theta$0)XC Here, C values are 1.69 for the type I. and 1.57 for the type II. 7.It was shown that the effect of the rise of water temperature was favorable when the thermal absorption was to be good by coloring the surface of the water warming pond and removing the bottom osmosis. 8.By enlarging the surface of water in comparison with the depth, and by having dead area of water in the water warming pond, this structure in the water warming pond is helpful for the rise of water temperature.