• Imaging Science in Dentistry
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• v.52 no.1
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• pp.83-91
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• 2022

Purpose: This study assessed the associations between chronological age, dental maturation (DM), cervical vertebrae maturation (CVM), and hand-wrist maturation (HWM) in individuals aged 9-19 years. In addition, this study aimed to derive practical methods to evaluate the skeletal age using DM, CVM, or HWM for orthodontic, medical, and forensic purposes and to compare which of these 3 developmental parameters is more accurate for estimating the age of individuals in a Turkish population. Materials and Methods: Panoramic, lateral cephalometric, and hand-wrist radiographs of 284 patients aged 9-19 years were used in this study. The DM, CVM, and HWM stages were determined. The Kolmogorov-Smirnov, kappa, Wilcoxon, Kruskal-Wallis, chi-square, and Spearman correlation tests and simple linear regression analysis were used for statistical analysis. The significance level was 0.05. Results: Statistically significant differences were found between chronological age and DM, chronological age and CVM, and chronological age and HWM in both sexes (P<0.05). DM did not show statistically significant differences according to sex (P>0.05), but CVM and HWM were statistically different between males and females (P<0.05). The DM-estimated age yielded more accurate values than the other methods. Conclusion: All correlations between skeletal and dental stages were statistically significant. Our results showed that there was no statistically significant difference between chronological age and DM-estimated age. Therefore, it can be concluded that DM stages have the potential to be used for legal purposes.

• New & Renewable Energy
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• v.17 no.2
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• pp.24-31
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• 2021

Renewable energy has become more popular with the increase in the use of solar power. Consequently, the disposal of defective and old solar panels is gradually increasing giving rise to a new problem. Furthermore, the efficiency and power output decreases with aging. Researchers worldwide are engaged in solving this problem by developing eco-module technologies that restore and reuse the solar panels according to the defect types rather than simple disposal. The eco-module technology not only solves the environmental problem, but also has economic advantages, such as extending the module life. Replacement of encapsulants contributes to a major portion of the module maintenance plan, as the degradation of encapsulants accounts for 60% of the problems found in modules over the past years. However, the current International Electrotechnical Commission (IEC) standard testing was designed for the commercialization of solar modules. As the problem caused by long-term use is not considered, this method is not suitable for the quality assurance evaluation of the eco-module. Therefore, to design a new accelerated test, this paper provides an overview of EVA degradation and comparison with the IEC and accelerated tests.

• Journal of Practical Engineering Education
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• v.13 no.3
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• pp.497-505
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• 2021

Test equipment for strain and vibration measurement was designed for educational purposes. Widely available and affordable materials were put into making this device. Three strain gauges placed on an iron ruler made cantilevered beam were used to measure values according to external load. An electromagnet triggered excitation and a function generator created vibration of the beam. We present three different tests conducted with this equipment regarding production of scales, measurement of resonant frequency, and calculation of the difference between excitation frequency and measured frequency. Overall, this paper presents a piece of simple yet inexpensive test equipment and its corresponding portfolio with expectations of being applied to the educational field for efficient measurement of load and vibration.

• Genomics & Informatics
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• v.18 no.3
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• pp.31.1-31.8
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• 2020

The coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become a global pandemic. No specific therapeutic agents or vaccines for COVID-19 are available, though several antiviral drugs, are under investigation as treatment agents for COVID-19. The use of convalescent plasma transfusion that contain neutralizing antibodies for COVID-19 has become the major focus. This requires mass screening of populations for these antibodies. While several countries started reporting population based antibody rate, its simple point estimate may be misinterpreted without proper estimation of standard error and confidence intervals. In this paper, we review the importance of antibody studies and present the 95% confidence intervals COVID-19 antibody rate for the Korean population using two recently performed antibody tests in Korea. Due to the sparsity of data, the estimation of confidence interval is a big challenge. Thus, we consider several confidence intervals using Asymptotic, Exact and Bayesian estimation methods. In this article, we found that the Wald method gives the narrowest interval among all Asymptotic methods whereas mid p-value gives the narrowest among all Exact methods and Jeffrey's method gives the narrowest from Bayesian method. The most conservative 95% confidence interval estimation shows that as of 00:00 on September 15, 2020, at least 32,602 people were infected but not confirmed in Korea.

• The Journal of Korea Robotics Society
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• v.17 no.2
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• pp.191-197
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• 2022

In this research, we developed the muscle-strength-assistant device, named as LEXO-W, and conducted suitability test for army when transporting high weights. LEXO-W relieves the burden when carrying heavy weights by distributing the load concentrated on the arms throughout the body. LEXO-W weighs 4 kg and is designed to handle objects weighing up to 55 kg. To verify the effectiveness of the device, object handling tests (high explosive shell, simple assembly bridges, and ammunition boxes) were conducted. Working time, metabolic rate, and electromyogram (EMG) signals were measured in each test. As a result, it was confirmed that the working time, metabolic rate and EMG signal before and after wearing LEXO-W were decreased. This research has great significance in that it verified the performance of the wearable device from the perspective of military operation.

• Steel and Composite Structures
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• v.42 no.6
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• pp.791-804
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• 2022

As a type of semi-rigid connection, the top and seat angle connections are popular in current structures owing to their good cyclic performance and simple erection. However, their stiffness and load bearing capacity are relatively insufficient. This study proposes two strengthening methods to further increase the stiffness and strength of bolted-angle joints while maintaining satisfactory energy dissipation capacity (EDC) and ductility. Cyclic loading tests were conducted on six joint specimens with different strengthened angle components. Based on the test results, the influence of the following important factors on the cyclic behavior of steel joint specimens was investigated: the position of the rib stiffeners (edge rib stiffeners and middle rib stiffener), steel strength grade of rib stiffeners (Q345 and Q690), and additional stiffeners or not. In addition, the finite element models of these specimens were built and validated through a comparison of experimental and numerical results. The stiffness and bearing capacity of the bolted-angle joints could be improved significantly by utilizing the novel strengthened joints proposed in this study. Moreover, this can be achieved with almost no increase in the amount of steel required, and the EDC of this joint could also satisfy the requirements of seismic codes from various countries.

• Geomechanics and Engineering
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• v.31 no.6
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• pp. 583-597
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• 2022

Frost heave can cause uneven ground uplift that may damage geo-infrastructure. To assist damage-prevention strategies, standard frost heave testing methods and frost susceptibility criteria have been established and used in various countries. ASTM International standard testing method is potentially the most useful standard, as abundant experimental data have been acquired through its use. ASTM International provides detailed recommendations, but the method is expensive and laborious because of the complex testing procedure requiring a freezing chamber. A simple frost heave testing method using a temperature-controllable cell has been proposed to overcome these difficulties, but it has not yet been established whether a temperature-controllable cell can adequately replace the ASTM International recommended apparatus. This paper reviews the applicability of the ASTM International testing method using the temperature-controllable cell. Freezing tests are compared using various soil mixtures with and without delivering blow to depress the freezing point (as recommended by ASTM International), and it is established that delivering blow does not affect heave rate, which is the key parameter in successful characterization of frost susceptibility. As the freezing temperature decreases, the duration of supercooling of pore water shortens or is eliminated; i.e., thermal shock with a sufficiently low freezing temperature can minimize or possibly eliminate supercooling.

• Proceedings of the SCSK Conference
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• 2003.09a
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• pp.73-84
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• 2003

Skin aging process on pre-menopausal women is a problem that needs to be prevented as early as possible. The decrease of oestrogen level which is one of the intrinsic factors of the skin aging process will affect the skin biological process, due to oestrogen receptors on the skin. A number of researches conducted on pre-menopausal women with the allocation of oestrogen hormone resulted in delaying the skin aging process. The administration of soy isoflavon, a phytoestrogen found in daily food, on pre-menopausal women is hoped to be able to prevent skin aging process, even clinically or molecular biologically. This research aims to explain the benefit of administering of soy isoflavon on skin aging process. The design of the research is randomised controlled trial (RCT). As many as 60 pre-menopausal women were collected with simple random sampling method. Soy isoflavon is an independent variable, while skin aging process is a dependent variable assessed from the hydration, sebum level, average roughness, depth of wrinkles, skin clarity, length of the telomere. Analysis was conducted using t and MANDVA tests and.the result showed a significance (F = 10,439; p = 0,001) over the allocation of soy isoflavon to the whole variable dependent, including the telomere length and the skin hydration, meant that allocation of soy isoflavon could delay skin aging process.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.34 no.3
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• pp.181-187
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• 2023

Objectives: This study aimed to investigate the correlation between the Comprehensive Attention Test, Korean-Wechsler Intelligence Scale for Children-Fourth Edition, and Attention-Deficit/Hyperactivity Disorder (ADHD) Rating Scale-IV scores in children and adolescents with ADHD. Methods: Fifty-five children and adolescents diagnosed with ADHD and not taking psychiatric medications were included in this retrospective study. A correlation analysis was performed. Results: Although simple visual and auditory selective attention have diagnostic value in traditional continuous performance tests, this study revealed that inhibition-sustained attention and interference-selective attention are also effective in evaluating ADHD. Furthermore, the correlation between the attention and intelligence test scores varied depending on the use of visual or auditory stimuli. Conclusion: The findings of this study contribute to clarifying our understanding of the cognitive characteristics of children and adolescents with ADHD and can be used in future research.

• Advances in nano research
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• v.15 no.2
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• pp.155-163
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• 2023

Exercise is beneficial to the body in some ways. It is vital for people who have heart problems to perform exercise according to their condition. This paper describes how an Android platform can provide early warnings of fatigue during wushu exercise using Photoplethysmography (PPG) signals. Using the data from a micro-electro-mechanical system (MEMS) gyroscope to detect heart rate, this study contributes an algorithm to determine a user's fatigue during wushu exercise. It sends vibration messages to the user's smartphone device when the heart rate exceeds the limit or is too fast during exercise. The heart rate monitoring system in the app records heart rate data in real-time while exercising. A simple pulse sensor and Android app can be used to monitor heart rate. This plug-in sensor measures heart rate based on photoplethysmography (PPG) signals during exercise. Pulse sensors can be easily inserted into the fingertip of the user. An embedded microcontroller detects the heart rate by connecting a pulse sensor transmitted via Bluetooth to the smartphone. In order to measure the impact of physical activity on heart rate, Wushu System tests are conducted using various factors, such as age, exercise speed, and duration. During testing, the Android app was found to detect heart rate with an accuracy of 95.3% and to warn the user when their heart rate rises to an abnormal level.