• Journal of the Korean Society of Marine Environment & Safety
• /
• v.25 no.3
• /
• pp.259-268
• /
• 2019

Even if only two ships are encountered, a collision may occur due to the mistaken judgment of the positional relationship. In other words, if an officer does not know a target ship's intention, there is always a risk of collision. In this paper, the experiments are conducted to investigate how the intention affects the action of collision avoidance in cooperative and non-cooperative situations. In non-cooperative situation, each ship chooses a course that minimizes costs based on the current situation. That is, it always performs a selfish selection. In a cooperative situation, the information is exchanged with a target ship and a course is selected based on this information. Each ship uses the Distributed Stochastic Search Algorithm so that a next-intended course can be selected by a certain probability and determines the course. In the experimental method, four virtual ships are set up to analyze the action of collision avoidance. Then, using the actual AIS data of eight ships in the strait of Dover, I compared and analyzed the action of collision avoidance in cooperative and non-cooperative situations. As a result of the experiment, the ships showed smooth trajectories in the cooperative situation, but the ship in the non-cooperative situation made frequent big changes to avoid a collision. In the case of the experiment using four ships, there was no collision in the cooperative situation regardless of the size of the safety domain, but a collision occurred between the ships when the size of the safety domain increased in cases of non-cooperation. In the case of experiments using eight ships, it was found that there are optimal parameters for collision avoidance. Also, it was possible to grasp the variation of the sailing distance and the costs according to the combination of the parameters, and it was confirmed that the setting of the parameters can have a great influence on collision avoidance among ships.

• Journal of Coastal Disaster Prevention
• /
• v.4 no.3
• /
• pp.119-131
• /
• 2017

Global warming under the influence of climate change and its direct impact on glacial and sea level are known issue. However, there is a lack of research on an indirect impact of climate change such as coastal structure design which is mainly based on a frequency analysis of water level under the stationary assumption, meaning that maximum sea level will not vary significantly over time. In general, stationary assumption does not hold and may not be valid under a changing climate. Therefore, this study aims to develop a novel approach to explore possible distributional changes in annual maximum sea levels (AMSLs) and provide the estimate of design water level for coastal structures using a multiple non-crossing quantile regression based nonstationary frequency analysis within a Bayesian framework. In this study, 20 tide gauge stations, where more than 30 years of hourly records are available, are considered. First, the possible distributional changes in the AMSLs are explored, focusing on the change in the scale and location parameter of the probability distributions. The most of the AMSLs are found to be upward-convergent/divergent pattern in the distribution, and the significance test on distributional changes is then performed. In this study, we confirm that a stationary assumption under the current climate characteristic may lead to underestimation of the design sea level, which results in increase in the failure risk in coastal structures. A detailed discussion on the role of the distribution changes for design water level is provided.

• Journal of Acupuncture Research
• /
• v.38 no.2
• /
• pp.110-121
• /
• 2021

The objective of this study was to conduct a systematic review and network meta-analysis to evaluate and compare the effectiveness of various types of acupuncture for menopausal hot flashes (HF). Randomized controlled trials (RCTs) were retrieved from 8 electronic databases, and the risk of bias was evaluated for the included studies. Pairwise meta-analysis and network meta-analysis were performed using Review Manager and R software for indirect comparison and ranking, respectively. In total, 23 RCTs (2,302 patients) were eligible for systematic review, of which 10 were included in network meta-analysis. Network meta-analysis showed manual acupuncture (MA) had the highest probability of reducing HF frequency and severity, followed by sham acupuncture (SA), electroacupuncture, usual care, or no treatment; furthermore, warm acupuncture significantly improved menopause-specific quality of life compared with MA or electroacupuncture. Compared with hormone replacement therapy, acupuncture had less efficacy in reducing HF frequency but enhanced menopause-specific quality of life. There was no significant difference between MA and SA in mitigating HF. The existing evidence showed that MA could be used for alleviating menopausal HF. However, it is recommended that more high-quality RCTs should be performed.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.41 no.3
• /
• pp.209-217
• /
• 2021

Although forest fires are more often triggered by artificial causes than by natural causes, the combustion conditions that spread forest fire damage over a large area are affected by natural phenomena. Therefore, using partial least squares structural equation modeling (PLS-SEM), which can analyze the dependent and causal relationships between various factors, this study evaluated the causal relationships and relative influences between forest fire, weather, and drought, taking Gangwon Province as our sample region. The results indicated that the impact of drought on forest fires was 27 % and that of the weather was 38 %. In addition, forest fires in spring accounted for about 60 % of total forest fires. This indicatesthat along with meteorological factors, the autumn and winter droughts in the previous year affected forest fires. In assessing the risk of forest fires, if severe meteorological droughts occur in autumn and winter, the probability of forest fires may increase in the spring of the following year.

• Journal of Dental Anesthesia and Pain Medicine
• /
• v.21 no.2
• /
• pp.139-153
• /
• 2021

Background: In anesthetic techniques, touching bones can cause needle bending. Theoretically, a needle should support such deflection without fracturing. However, it is possible that a needle may fracture depending on the quality and type of needle used. This study evaluated the physical, chemical, and micromorphological characteristics of long and short dental anesthetic needles, as well as the mechanical properties of flexural load and bending resistance when needles are subjected to different bending angles. Methods: Long and short needles (30G, Jets, Misawa, Selekto, Terumo, Unoject and 27G, Dencojet, Injex, Jets, Misawa, Procare, Setoject XL, Terumo) were evaluated. Scanning electron microscopy was used to evaluate the needle bevels and energy-dispersive X-ray spectroscopy was used for the chemical analysis of needle compositions. Flexural loading and bending strength assessments were performed using a universal testing machine by bending the needles (n = 5) to angles of 30°, 60°, or 90°, or until fracture occurred. Results: The Injex 27G, Jets 27G, and Septoject XL 27G needles were all less than 30 mm in length. There were small percentage variations in the chemical compositions of the needles. Superior smoothness was observed for the Unoject 30G needle, which exhibited the highest fracture resistance at 60°. The Jets 30G needle exhibited greater resistance to fractures at 90°. The Procare 27G needle exhibited the highest load resistance to bending, followed by the Septoject XL 27G needle, and both needles were tied for the lowest fracture resistance. No needle fractured when bent to 30° or at less than three bends to 60° or 90°. Conclusions: Greater needle resistance to bending increases the probability of early fracturing. Thinner and shorter needles are more resistant than longer and thicker needles. Performing a single bend does not result in any significant risk of fracture or obliterate the lumen, allowing for the continued passage of anesthetic liquid.

• The Journal of Asian Finance, Economics and Business
• /
• v.8 no.1
• /
• pp.573-585
• /
• 2021

The banking sector is one of the most important sectors in Pakistan's struggling economy. Recent studies have recommended that suitable methods can be applied to predict bankruptcy. In this context, this work analyzes Pakistan's banking sector's financial status through the five-factor Altman Z-score model, which determines the probability of bankruptcy for an organization. Banking data has been collected through the Pakistan Stock Exchange (PSX) in the period 2013-2017. The Z-score assessment criteria is defined as: Z> 2.99 - "safe" zone; Z> 1.8 Z>2.98- "grey" zone; and Z <1.8 - "distress" zone. Results show good predictions for the local banking industry, while most foreign Pakistani banks were found bankrupt with the Z-score below 1.1. One of the financial risks investors face when investing in any company is the risk of bankruptcy. One of the most used models for predicting financial distress for any company is Altman's Z-score model. On the other hand, the Z-score analysis suggests that all banking establishments are not bankrupt because they have sufficient ability to control bankruptcy. At the same time, foreign banks failed financially and would not be able to be sustained in the future because they do not have the ability to pay the short-term and long-term debt.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.63 no.2
• /
• pp.75-84
• /
• 2021

As the weather changes become frequent, weather disasters are increasing, causing more damage to plastic greenhouses. Among the damage caused by various disasters, damage by snow to the greenhouse takes a relatively long time, so if an alarm system is properly prepared, the damage can be reduced. Existing greenhouse design standards and snow warning systems are based on snow depth. However, even in the same depth, the load on the greenhouse varies depending on meteorological characteristics and snow density. Therefore, this study aims to secure the structural safety of greenhouses by developing sensors that can directly measure snow loads, and analysing the warning criteria for load using a stochastic model. Markov chain was applied to estimate the failure probability of various types of greenhouses in various regions, which let users actively cope with heavy snowfall by selecting an appropriate time to respond. Although it was hard to predict the precise snow depth or amounts, it could successfully assess the risk of structures by directly detecting the snow load using the developed sensor.

• Safety and Health at Work
• /
• v.13 no.1
• /
• pp.59-65
• /
• 2022

Background: Healthcare workers' attitudes toward vaccination have been widely described in the literature, but a restricted amount of studies assessed healthcare students' knowledge, attitudes, and opinions on this issue. This study aimed to estimate the influence of a degree course on knowledge and immunization behavior among healthcare students and to compare medical students with students from other health profession degree programs to identify possible differences. Methods: A multicenter, cross-sectional study was performed in 2018 in 14 Italian Universities (3,131 students were interviewed). A validated questionnaire was used to assess knowledge, attitudes, and opinions toward vaccinations, with a specific focus on influenza vaccine and attitudes toward mandatory vaccination policies. Statistical software STATA® 14 was used. Results: Significant differences were recorded between medical students and other healthcare students. The intention to get vaccinated against influenza during the next season and having been vaccinated in the previous season was higher in the medical group (p < 0.001). In the group of students of other health professions, we registered a lower probability of identifying themselves as a high-risk group for contracting infectious diseases as a consequence of their profession and health status (aOR 0.49; CI95%: 0.40-0.60) and an increased likelihood of defining their level of knowledge on vaccine-preventable diseases and related vaccinations as "insufficient/sufficient/fair" (aOR 1.31; CI95%: 1.11-1.56). Conclusions: Results show several differences between medical students and students of other health professions when it comes to vaccination knowledge, attitudes, and perceptions, as well as a general low tendency to be vaccinated against influenza.

• Journal of The Korean Society of Integrative Medicine
• /
• v.9 no.3
• /
• pp.47-58
• /
• 2021

Purpose : This study aimed to investigate the association between asthma and oral health and factors influencing asthma in adults. We also investigated whether asthma is related to mental health and physiological factors of blood. Methods : Data from 12,639 adults was taken from the 7th period (2016~2018) Korea National Health and Nutrition Examination Survey and analyzed using with SPSS 22.0 statistical program. Statistical analysis of data included frequency analysis, cross-analysis, and logistic regression analysis. For continuous data, an independent sample t-test was performed. The statistical significance level was defined as 0.05. Results : The probability of asthma occurrence was statistically different within general characteristics (gender, age, school grade, income, and drinking). By independent variables in a logistic regression analysis, the asthma diagnosis group had more people with speech discomfort (OR=1.37), chewing discomfort (OR=1.29), and oral pain (OR=.73). We found that people with asthma had a more unfavorable perception of their health (OR=1.73), suffered more depression (OR=.45), stress (OR=.66), and limited activity (OR=2.38). Moreover, the white blood cell count (OR=1.10) and high sensitivity C-reactive protein test (OR=1.06) also showed higher values than the control group. Conclusion : Our study showed that oral health and mental health were associated with the asthma, and influencing factors were oral health and behavior and mental health-related characteristics. Therefore, it is necessary to understand asthma-related risk factors for oral health and recognize the importance of systematic oral care education and regular dental visits for patients receiving asthma treatment. Thus, this study provides valuable insights on appropriate oral health management and prevention of asthma in patients.

• Earthquakes and Structures
• /
• v.22 no.2
• /
• pp.169-184
• /
• 2022

The importance of seismicity in developing countries and the strengthening of buildings is a topic of major importance. Therefore, the study of several solutions with the development of new technologies is of great importance to investigate the damage on retrofitted structures by using probabilistic methods. The Federal Emergency Management Agency considers three types of performance levels by considering different scenarios, intensity and duration. The selection and scaling of ground motions mainly depends on the aim of the study. Intensity-based assessments are the most common and compute the response of buildings for a specified seismic intensity. Assessments based on scenarios estimate the response of buildings to different earthquake scenarios. A risk-based assessment is considered as one of the most effective. This research represents a practical method for developing countries where exists many active faults, tall buildings and lack of good implementable approaches. Therefore, to achieve the main goal, two high-rise steel buildings have been modeled and assessed. The contribution of buckling-restrained braces in the elastic design of both buildings is firstly verified. In the nonlinear static range, both buildings presented repairable damage at the central top part and some life safety hinges at the bottom. The nonlinear incremental dynamic analysis was applied by 15 representative/scaled accelerograms to obtain levels of performance and fragility curves. The results shown that by using probabilistic methods, it is possible to estimate the probability of collapse of retrofitted buildings by buckling-restrained braces and tuned mass dampers, which are practical retrofitting options to protect existing structures against earthquakes.