• Steel and Composite Structures
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• v.51 no.2
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• pp.153-172
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• 2024

Due to the fast development of constructions in recent years, there has been a rapid consumption of fresh water and river sand. In the production of concrete, alternatives such as sea water and sea sand are available. The near surface mounted (NSM) technique is one of the most important methods of strengthening. Aluminum alloy (AA) bars are non-rusting and suitable for usage with sea water and sand concrete (SSC). The goal of this study was to enhance the shear behaviour of SSC-beams strengthened with NSM AA bars. Twenty-four RC beams were cast from fresh water river sand concrete (FRC) and SSC before being tested in four-point flexure. All beams are the same size and have the same internal reinforcement. The major factors are the concrete type (FRC or SSC), the concrete degree (C25 or C50 with compressive strength = 25 and 50 MPa, respectively), the presence of AA bars for strengthening, the direction of AA bar reinforcement (vertical or diagonal), and the AA bar ratio (0, 0.5, 1, 1.25 and 2 %). The beams' failure mechanism, load-displacement response, ultimate capacity, and ductility were investigated. Maximum load and ductility of C25-FRC-specimens with vertical and diagonal AA bar ratios (1%) were 100,174 % and 140, 205.5 % greater, respectively, than a matching control specimen. The ultimate load and ductility of all SSC-beams were 16-28 % and 11.3-87 % greater, respectively, for different AA bar methods than that of FRC-beams. The ultimate load and ductility of C25-SSC-beams vertically strengthened with AA bar ratios were 66.7-172.7 % and 89.6-267.9 % higher than the unstrengthened beam, respectively. When compared to unstrengthened beams, the ultimate load and ductility of C50-SSC-beams vertically reinforced with AA bar ratios rose by 50-120 % and 45.4-336.1 %, respectively. National code proposed formulae were utilized to determine the theoretical load of tested beams and compared to matching experimental results. The predicted theoretical loads were found to be close to the experimental values.

• Computers and Concrete
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• v.33 no.6
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• pp.707-724
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• 2024

This paper proposes a study of cement replacement with rice husk ash (RHA) and eggshell ash (ESA) for enhanced mechanical properties of geopolymer (GP) concrete with and without admixture. The main objective is to investigate the mechanical properties of GP with various replacement levels of Pozzolana Portland cement by RHA and ESA. The GP resistance to durability is examined and impact of ash materials on concrete's durability performance is determined. The environmental benefits of using agricultural waste materials in GP manufacturing minimize cement usage and CO2 emissions. The goal is to assess value of RHA-ESA of building material, paving stones for structures to lessen environmental impact. The novelty lies in use of ESA and RHA as partial replacements for cement and investigation of admixtures to enhance concrete properties, and reduce environmental impact. The research contributes by introducing a novel approach to reducing cement consumption by using ESA and RHA to address environmental concerns. It also explores the potential benefits of admixtures improving concrete performance and reducing environmental pollution. A study is carried with and without impacts of admixture to find compressive strength of GP cubes. The cement has been replaced by RHA and ESA in the range of (2.5%+7.5%, 5%+5%, 7.5%+2.5) by weight of cement for M20 mix. The compressive strength (CS) and split tensile strength (STS) at 7days, 14 days and 28 days is obtained as 21 N/mm2 at 7.5%RHA+2.5%ESA and 2.3 at 7.5%RHA+2.5%ESA, 24 N/mm2 at 7.5%RHA+2.5%ESA and 2.3 at 7.5%RHA+2.5%ESA, 28 N/mm2 at 7.5%RHA+2.5%ESA and 2.8 at 7.5%ESA respectively with normal curing condition.

• Journal of Gastric Cancer
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• v.24 no.3
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• pp.316-326
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• 2024

Purpose: This study was performed to assess the lifestyle-related behaviors of patients with gastric cancer (GC) and to investigate the associations between the time since GC diagnosis and these behaviors. Materials and Methods: This study included 29,478 adults (including 338 patients with GC) aged ≥ 40 years who participated in the Korea National Health and Nutrition Examination Survey 2014-2021. Multiple logistic regression analysis explored the associations between the time since GC diagnosis (patients diagnosed with GC less than 5 years ago [<5 years group] and those diagnosed with GC 5 or more than years ago [≥5 years group]) and lifestyle factors. Subgroup analyses were conducted based on age and sex. Results: The current smoking rate was not lower in the GC group than in the healthy group, regardless of time since diagnosis. Compared to the healthy controls, monthly alcohol intake was lower in the <5 years group (odds ratio [OR], 0.450; 95% confidence interval [CI], 0.275-0.736). The ≥5 years group showed a lower rate of strength training (OR, 0.548; CI, 0.359-0.838), compared with the healthy control group. Subgroup analysis focusing on the ≥5 years group revealed a significantly lower rate of strength training, particularly in patients aged ≥65 years and male patients (OR, 0.519 and 0.553; CI, 0.302-0.890 and 0.340-0.901, respectively). Conclusions: Clinicians should continue educating patients on lifestyle behavior modifications, particularly alcohol abstinence, even beyond 5 years after GC diagnosis. Education on strength training is especially important for patients ≥65 years or male patients.

• Nutrition Research and Practice
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• v.18 no.4
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• pp.534-543
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• 2024

BACKGROUND/OBJECTIVES: Studies on the impact of dietary fiber intake on kidney stones are few, and their results were controversial. This study aimed to explore the association between dietary fiber intake and kidney stones in the nationally representative population of the USA. SUBJECTS/METHODS: This cross-sectional research included 8,588 participants from the National Health and Nutrition Examination Survey, 2011 to 2018. Information regarding dietary fiber intake was obtained from a 24-h recall survey. Participants were categorized into different dietary fiber intake tertiles according to the average of 2 days of dietary recall data. The outcome was self-reported kidney stones. After adjusting for the traditional risk factors, a multivariate logistic regression model was used to examine the association between dietary fiber intake and kidney stones. RESULTS: Eight hundred seventy-two participants had kidney stones. The weighted prevalence (SE) of kidney stones in the lowest tertile, medium tertile, and highest tertile of dietary fiber intake was 11.8% (0.8%), 10.3% (0.8%), and 9.1% (0.8%), respectively. After adjusting for age, sex, race and ethnicity, education level, smoking status, alcohol consumption, physical activity, body mass index, hypertension, diabetes, dyslipidemia, daily water intake, chronic kidney disease stage 3-5, and total energy intake, participants with the highest tertile of fiber intake had a significantly lower risk of kidney stones (odds ratio [OR], 0.68; 95% confidence interval [CI], 0.48-0.95) compared to those in the lowest tertile. Every 5 g/day increment in dietary fiber intake was associated with a significant decrease in risk of kidney stones (OR, 0.90; 95% CI, 0.83-0.98). CONCLUSION: An increase in dietary fiber intake was associated with a lower risk of kidney stones, suggesting adults should be encouraged to maintain an adequate dietary fiber intake to prevent the development of kidney stones. Our results provide evidence to formulate nutrition management strategies for the prevention of kidney stones.

• Journal of Sasang Constitutional Medicine
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• v.36 no.2
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• pp.12-26
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• 2024

Objectives We aimed to identify the incidence of metabolic syndrome (MetS) and its clustering components according to constitution type and lifestyle risk factors in Korean adults. Methods This study included 1,978 adults aged 30-55 years from the Korean Medicine Daejeon Citizen Cohort (KDCC) study. We defined lifestyle factors including smoking, alcohol consumption, physical activity, sleep, dietary quality, and weight status. Total lifestyle scores were created based on the six lifestyle factors (ranging from 0 to 5 factors) and classified into two groups: unhealthy (0-2 factors), or healthy (3-5 factors). Cox proportional hazard regression was used to estimate the hazard ratio (HR) and 95% confidence intervals (CIs) of primary endpoints: MetS events and their clustering components. Results During a median follow-up of 2.2 years, we documented 125 new onsets of MetS. Compared with participants with healthy, the HR of unhealthy participants was 2.401 (95% CI: 1.497-3.851) for MetS incidence. After adjusting for covariates, TE type with unhealthy was higher HR values of abdominal obesity (HRs: 1.499, 95%CI: 1.061-2.117) and hypertension (HRs: 1.840, 95%CI: 1.032-3.277), respectively. Conclusion Unfavorable lifestyle factors were highly associated with the prevalence of MetS and its clustering such as abdominal obesity and hypertension in Korean adults with TE. Tailored health management is needed to consider individual traits and healthy lifestyles to prevent cardiometabolic diseases.

• Korean Journal of Agricultural Science
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• v.50 no.3
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• pp.395-406
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• 2023

The large amount of energy required for successful crop production is the main challenge in greenhouse cropping systems. As a response to this challenge a comprehensive evaluation of greenhouse energy consumption was carried out in two structurally similar single-span greenhouses with different thermal curtain positions, with particular attention to energy productivity, specific energy, net energy, and energy ratio. The greenhouses are used for strawberry production. In the R-greenhouse (RGH), the thermal curtain hanged directly at the roof ridge, whereas in the Q-greenhouse (QGH), the thermal curtain was placed 5° from an imaginary vertical axis, from the middle of the roof ridge downwards to the north side of the greenhouse roof. The relevant data were recorded using standard methods. The results indicated that the energy expended in the RGH and QGH systems was 2,186.48 and 2,189.26 MJ/m², respectively. Electricity and nitrogen fertilizer contributed the highest energy input in both greenhouses and in all seasons. The output energy was 3.12 and 3.82 MJ/m², respectively, in RGH and QGH in season I and 4.40 and 4.87 MJ/m² in season II. In terms of energy expended, there was no significant difference between the two greenhouses, nor between the two seasons. These results indicate that greenhouses of the size used in this investigation are not viable in terms of energy productivity, energy-use efficiency, and subsequent economic performance. However, further studies should be conducted to scale-up the information obtained from this investigation.

• Journal of Preventive Medicine and Public Health
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• v.57 no.4
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• pp.379-387
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• 2024

Objectives: Mental health issues have become a growing concern worldwide. Research has shown that regular physical activity (PA) can positively affect mental health. This study investigated the associations between PA and mental health problems (MHPs) in middle-aged Indonesians. Methods: The study utilized data from the 2018 Indonesian Basic Health Research Survey and used a cross-sectional approach. The participants included individuals aged 40-60 years who completed the 20-question Self-Reporting Questionnaire. A logistic regression was performed to analyze a sample of 263 930 data points. Results: Nearly 10.4% of the participants suffered from mental health issues. Notably, among those who did not engage in moderate and vigorous PA, a sign of MHPs was found in 12.5% of participants. Those who met World Health Organization standards for PA were less likely to experience MHPs (10.1%). This study found a significant association between PA and mental health. After adjusting for smoking, alcohol consumption, non-communicable diseases, and socio-demographic variables like age, sex, education, occupation, marital status, and residence, the connection between PA and mental health became even stronger (adjusted odds ratio, 0.81; 95% confidence interval, 0.78 to 0.85; p<0.001). Conclusions: Regular PA has been shown to affect mental health positively. Therefore, it is important to improve health education and efforts to raise awareness among middle-aged Indonesians about the importance of PA in maintaining good mental health.

• Annals of Occupational and Environmental Medicine
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• v.34
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• pp.33.1-33.13
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• 2022

Background: Circadian rhythm disturbance caused by shift work has adverse effects on the metabolic homeostasis of the liver. Disruption of the metabolic homeostasis of the liver causes fat accumulation in the liver. The aim of this study was to investigate the correlation between shift work and non-alcoholic fatty liver disease (NAFLD) among male workers in the steel manufacturing industry of Korea. Methods: Based on medical examination data collected in June 2020, 2,511 male subjects from one steel manufacturing company in Korea were selected in total. NAFLD was evaluated using abdominal ultrasound, which was performed by two experienced radiologists. The multinomial logistic regression analysis was performed by adjusting for age, physical activity, smoking history, alcohol consumption, body mass index, waist circumference, blood pressure, blood glucose, lipidemia, liver function test, employment duration, and hepatotoxic materials exposure status. Results: Compared to daytime workers, the odds ratio (OR) of moderate-severe NAFLD in shift workers was 1.449 (95% confidence interval [CI], 1.028-2.043). Compared to daytime workers, the ORs of moderate-severe NAFLD were significantly higher for the group that engaged in total shift work for more than 20 years (OR, 2.285; 95% CI, 1.051-4.970), the group that was not allowed to sleep during night shift work (OR, 1.463; 95% CI, 1.030-2.078), and the group that consumed food during night shift work (OR, 1.580; 95% CI, 1.093-2.284). Conclusions: There was a correlation between shift work and moderate-severe NAFLD in male steel manufacturing workers. There will be a need for more research related to the correlation of shift work with steatohepatitis and cirrhosis in the future.

• 전자공학회논문지 IE
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• v.45 no.1
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• pp.31-37
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• 2008

A Wibro RF down converter of 2.3GHz band is designed and implemented in this paper. The problems that can occur in the receiver LNA(Low Noise Amplifier) to minimize additional purposes. In addition, 2.3GHz band from the 75 MHz downward to minimize the losses in the process, transform and improve efficiency, and achieve stable characteristics can be used to make high frequency characteristics of the device. Wibro repeater uses a TDMA(Time Division Multiplexing Access) method is needed because the RF switch. Production criterion specification, the input voltage from +8 V 1.2A of current consumption, 60dB gain and the noise figure of less than 2.5dB, VSWR(Voltage Standing Wave Ratio) less than 1.5, more than IMD(Inter Modulation Distortion) 60dB satisfied. Environmental conditions ($-20^{\circ}C$ to $70^{\circ}C$) to pass the test of reliability in a long time, that seemed crafted Wibro down converter be applied to the Wibro repeater.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.12
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• pp.1097-1107
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• 2015

General VTOL aircraft uses gas turbine engine which has high power to weight ratio. However, in the VTOL UAV in small sector, the gas turbine as a prime mover is not adequate because of the limitation of the high fuel consumption ratio of the gas turbine. In this research, The Series Hybrid-Electric Propulsion System(SHEPS) has been proposed and technology survey & comparison analysis has conducted to constitute propulsion system for engine, electric motor and battery. To achieve this object a 65kg-class P-UAV from "Company I" was used. And to estimate the validity of power control algorithm and developed power management control, Matlab/simulink$^{(R)}$ has been used for the simulation. As a result, the developed algorithm worked comparatively well and the research has predicted that SHEPS was satisfied enough for 7 hour of endurance for mission profile.