Murat, Aras;Tolga, Yilmaz;Ozlem, Caliskan;Ozgur, Anil;R. Tugrul, Erdem;Turgut, Kaya
Structural Engineering and Mechanics
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v.84
no.5
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pp.619-632
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2022
Reinforced concrete (RC) structures may be subjected to sudden dynamic impact loads such as explosions occurring for different reasons, the collision of masses driven by rockfall, flood, landslide, and avalanche effect structural members, the crash of vehicles to the highway and seaway structures. Many analytical, numerical, and experimental studies focused on the behavior of RC structural elements such as columns, beams, and slabs under sudden dynamic impact loads. However, there is no comprehensive study on the behavior of the RC column-beam connections under the effect of sudden dynamic impact loads. For this purpose, an experimental study was performed to investigate the behavior of RC column-beam connections under the effect of low-velocity impact loads. Sixteen RC beam-column connections with a scale of 1/3 were manufactured and tested under impact load using the drop-weight test setup. The concrete compressive strength, shear reinforcement spacing in the beam, and input impact energy applied to test specimens were taken as experimental variables. The time histories of impact load acting on test specimens, accelerations, and displacements measured from the test specimens were recorded in experiments. Besides, shear and bending crack widths were measured. The effect of experimental variables on the impact behavior of RC beam-column connections has been determined and interpreted in detail. Besides, a finite element model has been established for verification and comparison of the experimental results by using ABAQUS software. It has been demonstrated that concrete strength, shear reinforcement ratio, and impact energy significantly affect the impact behavior of RC column-beam connections.
For large scale power applications of HTS conductor, it is getting more important to have a stacked HTS coated conductor with low loss and large current capacity. But it was not easy to measure some electric properties. Stabilizer free YBCO CC for striated/ stacked conductors is easily burned out during the measurement of the critical current density because it has no stabilizer and it is difficult to set-up the current lead and voltage taps because it has many pieces of YBCO CC in a conductor. Instead of direct measuring the critical current of a stacked HTS coated conductor, indirect estimation from measuring a magnetization loss of HTS coated conductor could be useful for practical estimation of the critical current. The magnetization loss of a superconductor is supposed to be affected by a full penetrating magnetic field, and it tends to show an inflection point at the full penetrating magnetic field when we generate the graph of magnetization loss vs. external magnetic field. The full penetrating magnetic field depends on the shape of the conductor and its critical current density, so we can estimate the effective critical current density from measuring the magnetization loss. In this paper, to prove the effectiveness of this indirect estimation of the critical current, we prepared several different kinds of YBCO CC(coated conductor) including a stacked conductor short samples and measured the magnetization losses and the critical currents of each sample by using linked pick up coils and direct voltage measurement with transport current respectively.
Ahmad Hammad Hassan;Aref-Ali Gharooni;Harry Mee;James Geffner;Fahim Anwar
Journal of Trauma and Injury
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v.36
no.1
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pp.39-48
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2023
Purpose: Sports offer several health benefits but are not free of injury risk. Activity dynamics vary across sports, impacting the injury profile and thereby influencing healthcare resource utilization and health outcomes. The purpose of this study was to investigate sports-related major trauma cases and compare differences across sports and activity groups. Methods: A retrospective case notes review of sports-related major traumas over a 5-year period was conducted. Demographic, hospital episode-related, and health outcome-related data were analyzed, and differences were compared across sports and activity groups. The Glasgow Outcome Scale (GOS) at discharge was used as the primary outcome measure and the length of hospital stay as the secondary outcome measure. Results: In total, 76% of cases had good recovery at discharge (GOS, 5), 19% had moderate disability (GOS, 4), and 5% had severe disability (GOS, 3). The mean length of hospital stay was 11.2 days (range, 1-121 days). The most severely injured body region was the limbs (29.1%) and vertebral/spinal injuries were most common (33%) in terms of location. A significant difference (P<0.05) existed in GOS across sports groups, with motor sports having the lowest GOS. However, no significant differences (P>0.05) were found in other health-outcome variables or injury patterns across sports or activity groups, although more competitive sports cases (67%) required admission than recreational sports cases (33%). Conclusions: Spinal injuries are the most frequent sports injuries, bear the worst health outcomes, and warrant better preventive measures. Head injuries previously dominated the worst outcomes; this change is likely due to better preventive and management modalities. Competitive sports had a higher injury frequency than recreational sports, but no difference in health outcomes or injury patterns.
Water electrolysis holds great potential as a method for producing renewable hydrogen fuel at large-scale, and to replace the fossil fuels responsible for greenhouse gases emissions and global climate change. To reduce the cost of hydrogen and make it competitive against fossil fuels, the efficiency of green hydrogen production should be maximized. This requires superior electrocatalysts to reduce the reaction energy barriers. The development of catalytic materials has mostly relied on empirical, trial-and-error methods because of the complicated, multidimensional, and dynamic nature of catalysis, requiring significant time and effort to find optimized multicomponent catalysts under a variety of reaction conditions. The ultimate goal for all researchers in the materials science and engineering field is the rational and efficient design of materials with desired performance. Discovering and understanding new catalysts with desired properties is at the heart of materials science research. This process can benefit from machine learning (ML), given the complex nature of catalytic reactions and vast range of candidate materials. This review summarizes recent achievements in catalysts discovery for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The basic concepts of ML algorithms and practical guides for materials scientists are also demonstrated. The challenges and strategies of applying ML are discussed, which should be collaboratively addressed by materials scientists and ML communities. The ultimate integration of ML in catalyst development is expected to accelerate the design, discovery, optimization, and interpretation of superior electrocatalysts, to realize a carbon-free ecosystem based on green hydrogen.
Purpose - This paper assesses the trade potential and efficiency of Korea and China in the aquatic products trade. Trade efficiency and potential are the main factors that affect the growth of a country's trade. In this study, a time-varying stochastic frontier trade gravity model was constructed to analyze the trade potential and efficiency between Korea and China. By integrating the results of trade theory and empirical analysis, measures and suggestions were proposed to encourage the release of trade potential of fish exports between Korea and China. Design/methodology - In this paper, GDP per capita instead of economic size was chosen as an explanatory variable, and population size and relative distance were selected as explanatory variables to measure trade potential. For trade non-efficiency terms, regional organizations, political factors, and economic factors were mainly considered, and variables such as free trade agreements, political stability, regulatory quality, government efficiency, currency freedom, investment freedom, financial freedom, and trade freedom were selected. Panel data for South Korea and 14 aquatic products trading partners (including China) from 2002 to 2020 were used in the empirical analysis. Findings - In the past 19 years, South Korea's export trade potential of aquatic products to China has never been lower than 70%. It was above 90% from 2006 to 2018, and has been at a high level for a long time. This shows that China's aquatic product market has large potential for development. Originality/value - This study examines the effectiveness and potential of South Korea's exports of aquatic items to China in a methodical and comprehensive empirical manner. The evaluation of the export trade potential of South Korea's aquatic goods to China is more precise when the effects of regional organization, political, and economic variables are taken into account in the trade non-efficiency term of the stochastic frontier gravity model. At the same time, we propose to increase the scale of South Korea's aquatic products trade from the perspective of China's demand. This issue of trade studies is underexplored both empirically and in theory, although the issue has long been important to Korean and world trade.
Bo Young Park;Han A Cho;So Yeong Bang;Min Jeung Oh;Eun Ji Lee;Whan Hui Lee;Jae Min Joung;Mi Sook Yoon
Journal of Korean Academy of Dental Administration
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v.11
no.1
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pp.89-95
/
2023
Social phobia is a mental disorder that triggers physical reactions, such as cold sweats, headaches, and panic attacks, as a result of anxiety about a particular situation. Individuals with social phobia are thought to be more sensitive to dental anxiety and may have difficulty visiting the dentist as a result. This study aimed to determine the relationship between social phobia and dental fear among college students, who are reported to have a high prevalence of social phobia. A total of 120 survey responses were analyzed. To investigate the variation in dental fear levels based on the level of social phobia, the total social phobia score was divided into two groups: 41 points or more, and 40 points or less. The disparity in dental fear scores was then analyzed using a t-test. The study found that the average score for dental fear was statistically significantly higher in the group with a total social phobia score of 41 points or more compared to the group with a total score of 40 points or less (p<0.05). Furthermore, the group that scored 41 points or higher on the social phobia scale reported experiencing symptoms such as feeling nauseous at the dentist (3.29 points), sweating upon entering the dentist (3.13 points), and feeling afraid when looking at the dentist (3.13 points). The score was high (p<0.05). Therefore, dental patients exhibiting anxiety symptoms require a comfortable treatment environment to alleviate dental fear, and safe, pain-free dental treatment techniques must be employed.
The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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v.14
no.3
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pp.155-162
/
2009
To characterize the initiation, propagation and termination of Cochlodinium polykrikoides blooms in the southeast coastal waters of Korea, 2008, we analyzed the data set of phytoplankton composition, physical and chemical water properties, and meterological data. C. polykrikoides bloom in 2008 were long lasting and restricted to the coastal area with a low density. Our results indicate that C. polykrikoides blooms were affected by the atypical cold waters occurring in east-south coastal water in the early July. The cold water masses probably protected the free living cells of C. polykrikoides from entering into the coastal area from offshore waters as a pelagic seed population. The low density blooms of small scale established possibly by the germination of C. polykrikoides cyst in shallow coastal bottom could have not spread over because of the weak wind and low nutrient concentrations caused by severe drought in July and September.
June Park;Jaeseung Shin;In Kyung Min;Heejin Bae;Yeo-Eun Kim;Yong Eun Chung
Korean Journal of Radiology
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v.23
no.4
/
pp.402-412
/
2022
Objective: To evaluate the image quality and lesion detectability of lower-dose CT (LDCT) of the abdomen and pelvis obtained using a deep learning image reconstruction (DLIR) algorithm compared with those of standard-dose CT (SDCT) images. Materials and Methods: This retrospective study included 123 patients (mean age ± standard deviation, 63 ± 11 years; male:female, 70:53) who underwent contrast-enhanced abdominopelvic LDCT between May and August 2020 and had prior SDCT obtained using the same CT scanner within a year. LDCT images were reconstructed with hybrid iterative reconstruction (h-IR) and DLIR at medium and high strengths (DLIR-M and DLIR-H), while SDCT images were reconstructed with h-IR. For quantitative image quality analysis, image noise, signal-to-noise ratio, and contrast-to-noise ratio were measured in the liver, muscle, and aorta. Among the three different LDCT reconstruction algorithms, the one showing the smallest difference in quantitative parameters from those of SDCT images was selected for qualitative image quality analysis and lesion detectability evaluation. For qualitative analysis, overall image quality, image noise, image sharpness, image texture, and lesion conspicuity were graded using a 5-point scale by two radiologists. Observer performance in focal liver lesion detection was evaluated by comparing the jackknife free-response receiver operating characteristic figures-of-merit (FOM). Results: LDCT (35.1% dose reduction compared with SDCT) images obtained using DLIR-M showed similar quantitative measures to those of SDCT with h-IR images. All qualitative parameters of LDCT with DLIR-M images but image texture were similar to or significantly better than those of SDCT with h-IR images. The lesion detectability on LDCT with DLIR-M images was not significantly different from that of SDCT with h-IR images (reader-averaged FOM, 0.887 vs. 0.874, respectively; p = 0.581). Conclusion: Overall image quality and detectability of focal liver lesions is preserved in contrast-enhanced abdominopelvic LDCT obtained with DLIR-M relative to those in SDCT with h-IR.
Han, Dong Kyun;Cheon, Jin Sook;Choi, Young Sik;Kim, Ho Chan;Oh, Byoung Hoon
Korean Journal of Psychosomatic Medicine
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v.24
no.2
/
pp.227-235
/
2016
Objectives : The aims of this study were to know the frequency of cognitive dysfunction among patients with autoimmune thyroid disorders, and to reveal influencing factors on it, especially to clarify association with autoimmune thyroid antibodies. Methods : From sixty-five female patients with autoimmune thyroid disorders, demographic data were obtained by structured interview. Their cognitive funtions were measured using the MMSE-K and the MoCA-K tests. Depression was evaluated by the K-HDRS. Results : 1) Among patients with autoimmune thyroid disorders, 7.69% of them were below 24 on the MMSE-K, while 10.77% were below 22 on the MoCA-K. The frequency of cognitive deficit was not significantly different according to having positivity to antimicrosomal antibodies or not. 2) The antimicrosomal antibody-positive patients had significantly higher antithyroglobulin antibody titers, antimicrosomal antibody titers, and TSH concentration, while had significantly lower free T4 levels(p<0.05, respectively). 3) The total scores of the MMSE-K and the MoCA-K had significant correlation with age, marital status, antithyroglobulin antibody titers and K-HDRS(p<0.05, respectively). 4) The regression analysis revealed that variables such as age, education, autoimmune thyroid antibodies, thyroid function and depression did not influence on cognitive function of patients with autoimmune thyroid disorders. Conclusions : Our results could not support that cognitive function of patients with autoimmune thyroid disorders had correlation with autoimmune thyroid antibodies.
Hwang, Min Hee;Kim, Do Yeon;Cho, In Sun;Kim, Mi Hyung;Kwon, Hyun Sook;Kim, Jong Bo;Kim, Su Jung;Kim, Sun Hyung
Journal of Plant Biotechnology
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v.48
no.3
/
pp.179-185
/
2021
Indoor gardening includes wall greening, terrariums, and flower arrangements. Among these types of indoor gardens, the terrarium is easy to access for the general public, but in Korea, because of the focus on esthetics, the original purpose of creating terrariums, which was to grow plants sustainably in an enclosed space, has been lost. In addition, miniaturization of plants is required to grow plants in an enclosed space. Since the available plant species suitable for a terrarium are limited, only plants such as succulents, cacti, and moss have been used. In this study, Bronze (X Graptosedum) was used, and these problems were solved using the following three methods: placement and growth of virus-free plants in the terrarium; extending the diversity of plants with minimal size that can be planted in terrariums; and reducing the price of in vitro plants with minimal size by achieving large-scale production. In particular, tissue-cultured succulents were developed into a Vivorium by replacing the tissue culture container and renewing the composition of the plant. This paper suggests a new indoor horticultural field, Vivorium, that can improve the current limitations of terrariums and make them more accessible to the general public. The introduction and popularization of new indoor gardening fields with the increase in single-person households and indoor activities in the Pandemic era can also improve psychological stability among people and in the society.
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