• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.3
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• pp.191-208
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• 2024

In this study, a hydro-mechanical-damage coupled analysis model was developed to evaluate the structural safety of radioactive waste disposal structures. The Mazars damage model, widely used to model the fracture behavior of brittle materials such as rocks or concrete, was coupled with conventional hydro-mechanical analysis and the developed model was verified via theoretical solutions from literature. To derive the numerical input values for damage-coupled analysis, uniaxial compressive strength and Brazilian tensile strength tests were performed on concrete samples made using the mix ratio of the disposal concrete silo cured under dry and saturated conditions. The input factors derived from the laboratory-scale experiments were applied to a two-dimensional finite element model of the concrete silos at the Wolseong Nuclear Environmental Management Center in Gyeongju and numerical analysis was conducted to analyze the effects of damage consideration, analysis technique, and waste loading conditions. The hydro-mechanical-damage coupled model developed in this study will be applied to the long-term behavior and stability analysis of deep geological repositories for high-level radioactive waste disposal.

• Journal of the Institute of Convergence Signal Processing
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• v.24 no.4
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• pp.178-185
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• 2023

Rapid urbanization and advancements in technology have led to a surge in the number of automobiles, resulting in frequent traffic accidents, and consequently, an increase in human casualties and economic losses. Therefore, there is a need for technology that can predict the risk of traffic accidents to prevent them and minimize the damage caused by them. Traffic accidents occur due to various factors including traffic congestion, the traffic environment, and road conditions. These factors give traffic accidents spatiotemporal characteristics. This paper analyzes traffic accident data to understand the main characteristics of traffic accidents and reconstructs the data in a time series format. Additionally, an LSTM-MLP based model that excellently captures spatiotemporal characteristics was developed and utilized for traffic accident prediction. Experiments have proven that the proposed model is more rational and accurate in predicting the risk of traffic accidents compared to existing models. The traffic accident risk prediction model suggested in this paper can be applied to systems capable of real-time monitoring of road conditions and environments, such as navigation systems. It is expected to enhance the safety of road users and minimize the social costs associated with traffic accidents.

• Annals of Occupational and Environmental Medicine
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• v.34
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• pp.23.1-23.14
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• 2022

Background: The musculoskeletal disease (MSD) burden is an important health problem among Korean fishers. We aimed to investigate the indicators of the prevalence of MSD and contributions of significant indicators to MSD in Korean fishers. Methods: This cross-section study included 927 fishers (male, 371; female, 556) aged 40 to 79 years who were enrolled from 3 fishery safety and health centers. The outcome variable was one-year prevalence of MSD in 5 body parts (the neck, shoulder, hand, back, and knee). Independent variables were sex, age, educational attainment, household income, job classification, employment xlink:type, hazardous working environment (cold, heat, and noise), ergonomic risk by the 5 body parts, anxiety disorder, depression, hypertension, diabetes, and hyperlipidemia. The adjusted odds ratio of MSDs by the 5 body parts were calculated using multiple logistic regression analysis. We computed the population attributable fraction (PAF) for each indicators of MSDs using binary regression models. Results: The one-year prevalence of MSD in the neck, shoulder, hand, back, and knee was 7.8%, 17.8%, 7.8%, 27.2%, and 16.2% in males vs. 16.4%, 28.1%, 23.0%, 38.7%, and 30.0% in females, respectively. The ergonomic risk PAF according to the body parts ranged from 22.8%-59.6% in males and 22.8%-50.3% in female. Mental diseases showed a significant PAF for all body parts only among female (PAF 9.1%-21.4%). Cold exposure showed a significant PAF for the neck, shoulder, and hand MSD only among female (25.6%-26.8%). Age was not a significant indicator except for the knee MSD among female. Conclusions: Ergonomic risk contributed majorly as indicators of MSDs in both sexes of fishers. Mental disease and cold exposure were indicators of MSDs only among female fishers. This information may be important for determining priority risk groups for the prevention of work-related MSD among Korean fishers.

• Journal of Internet Computing and Services
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• v.25 no.3
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• pp.71-81
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• 2024

In response to the COVID-19 pandemic, the global airport industry is actively introducing 4th Industrial Revolution technology-based systems for quarantine and passenger safety, and test bed construction and prior verification using airport infrastructure and resources are actively being conducted. Analysis of recent cases shows that despite the changing travel patterns of airport users and the diversification of airport service demands, most testbeds construction studies are still focused on suppliers, and task prioritization is also determined by decision makers. There is a tendency to rely on subjective judgment. In order to find practical ways to become a first mover that leads innovation in the aviation industry, this study selected tasks and derived priorities to build testbeds from a service perspective that reflects various customer service needs and changes. Research results using the AHP analysis method resulted in priorities in the order of access transportation and parking services (29.2%), security screening services (23.4%), and departure services (21.8%), and these analysis results were tested in the airport industry. It shows that innovation in testbeds construction is an important factor. In particular, the establishment of smart parking and UAM transportation testbeds not only helps strengthen airports as centers of technological innovation, but also promotes cooperation with companies, research institutes, and governments, and provides an environment for testing and developing new technologies and services. It can be a foundation for what can be done. The results and implications produced through this study can serve as useful guidelines for domestic and foreign airport practitioners to build testbeds and establish strategies.

• Applied Chemistry for Engineering
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• v.35 no.3
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• pp.200-208
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• 2024

Chung's equations-IX and Chung's equation-XII were utilized to predict the fire risk and evaluate fire risk ratings for four types of wood: camphor, cherry, rubber, and elm trees. The combustion tests were conducted using a cone calorimeter test method by ISO 5660-1 standards. The fire risk and fire risk rating (FRR) were compared for Fire Risk Index-IX (FRI-IX) and Fire Risk Index-XII (FRI-XII). The results yielded Fire Performance Index-XI (FPI-XI) ranging from 0.08 to 11.48 and Fire Growth Index-XI (FGI-XI) ranging from 0.67 to 111.89. The Fire Risk Index-XII (FRI-XII), indicating fire risk rating, exhibited an increasing order of cherry (0.45): Grade A (Ranking 5) < PMMA (1): Grade A (Ranking 4) < elm (1.23): Grade A (Ranking 3) < rubber (1.56): Grade A (Ranking 2) << camphor (148.23): Grade G (Ranking 1). Additionally, the fire risk index-IX (FRI-IX) was cherry (0): Grade A (Ranking 3) ≈ rubber (0): Grade A (Ranking 3) ≈ elm tree (0): Grade A (Ranking 3) < PMMA (1): Grade A (Ranking 2) << camphor tree (66.67): Grade G (Ranking 1). In general, camphor was found to have the highest fire risk. In conclusion, although the expression of the index is different as shown based on the standards of FRI-IX and FRI-XII, predictions based on fire risk assessment of combustible materials showed similar trends.

• Korean Journal of Organic Agriculture
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• v.32 no.2
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• pp.233-245
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• 2024

In a field study, we investigated the consequences associated with the irrigation of red pepper with water contaminated by three types of veterinary antibiotics (amoxicillin, oxytetracycline, and chlortetracycline) on the soil residue, the absorption-translocation, and crop yields. As a result of evaluating the residue of veterinary antibiotics in pepper cultivation soil treated with veterinary antibiotics a total of 7 times from June 7 to August 26, 2023, the three antibiotics were not detected at the background level, but in the group treated with 10-fold and 50-fold of the background level was detected at a level of 2-10 ㎍/kg. For the leaf (stem) and fruit of red pepper, all three types of veterinary antibiotics were found to be below the detection limit at all treatments. However, trace levels were detected in red pepper roots. If veterinary antibiotics are unintentionally introduced into agricultural soil in the short term, the soil environment and crop safety will not be a problem. However, long-term introduction of veterinary antibiotics in agricultural soil may have negative effects by affecting soil microbial diversity and antibiotic resistance problems, so continuous monitoring and risk assessment are deemed necessary.

• Nuclear Engineering and Technology
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• v.56 no.5
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• pp.1925-1931
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• 2024

The study conducted in the northwest region of Jordan aimed to assess the levels of natural radioactivity in soil and olive mill pomace (OMP) samples. The researchers used Nal (TI) gamma-ray spectrometry to measure the activity concentrations of ²²⁶Ra, ²³²Th, ⁴⁰K, and ¹³⁷Cs in the samples. The average activity concentrations of ²²⁶Ra, ²³²Th, ⁴⁰K, and ¹³⁷Cs in the soil samples were found to be 18.624 ± 5.82, 12.276 ± 5.728, 518.33 ± 212.57, and 0.140 ± 0.09 (Bq, kg^-1), respectively. In the OMP samples, the average activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K were 7.272 ± 4.386, 3.454 ± 1.503, and 169.997 ± 81.873 (Bq kg^-1), respectively, and no ¹³⁷Cs was detected. The study also investigated fundamental parameters associated with radon, specifically the radon emanation coefficient (Rn_EC) and radon mass exhalation rate (E_x). The Rn_EC values ranged from 0.621 to 0.78 (Bq kg^-1), with an average value of 0.71 ± 0.06 (Bq kg^-1). The estimated E_x from the soil samples ranged from 65.83 to 124.86 (mBq kg^-1h^-1), with an average value of 99.74 ± 21.73 (mBq kg^-1h^-1). Regarding radiological hazards, the study examined various parameters, including radium equivalent activity, external and internal hazard indices, gamma and alpha indices, absorbed gamma dose rate, and excess lifetime cancer risk. All of these assessed values were found to be below the worldwide recommended limits for radiological safety. Additionally, the study analyzed the concentrations of gross alpha and gross beta radioactivities in soil and OMP samples. The soil samples had an average gross alpha activity of 4.642 ± 1.04 (Bq kg^-1) and an average gross beta activity of 48.13 ± 14.50 (Bq kg^-1). The OMP samples showed an average gross alpha activity of 0.32 ± 0.27 (Bq kg^-1) and an average gross beta activity of 59.19 ± 12.94 (Bq kg^-1). Overall, the obtained results are crucial for evaluating the radiological risks associated with natural radioactivity in the northwest region of Jordan. The findings establish baseline data for comparison and reference for radioactivity levels in the environment.

• Journal of Navigation and Port Research
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• v.48 no.4
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• pp.335-341
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• 2024

Recently, research, development, and commercialization of maritime autonomous surface ships (MASS) and remote control are in progress. Remote control is intended to secure autonomous navigation environments for existing ships or early-stage MASS using a remote control system (RCS). The main function of an RCS is to control MASS using data transmission between the MASS and the remote control centre. Remote control by a remote control officer also has an important function. The purpose of this study was to develop RCS and a performance evaluation technique for operation data provided by the RCS. The experiment was conducted during the navigation period of a training ship 'Hannara' after building experimental equipment at both an onshore remote control center and a training ship. As a result of evaluating data transmitted and received using the developed RCS, it was confirmed that data transmission was possible within an error range of 0.1%p. Fourteen types of ship information reflecting the navigation environment of the training ship were confirmed to be transmitted and received. The RCS developed in this work complies with the three principles of remote control: safety, reliability, and availability. This study provides a core technology for the development of RCSs for MASS and the evaluation of data transmission performance.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.5
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• pp.449-461
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• 2024

The use of tunnel boring machine (TBM), a mechanized excavation method with low noise and vibration and high safety compared to NATM method, has increased globally. In particular, slurry shield TBMs are used in subsea and submarine sections because they have an advantage in high pressure compared to EPB (earth pressure balanced) methods. As such, the used water of slurry shield TBMs is discharged through wastewater treatment facilities. In the case of large-scale TBMs, the amount of water used is enormous, so it should be recycled to reduce costs and protect the environment. Various types of additives are used to improve the performance of the slurry treatment plant (STP) and filter press. Among them, coagulants improve the productivity of the filter press by neutralizing the charges on particles. In this study, lab tests were conducted to evaluate the reusability of the used water through the filter press after flocculants were added.

• Journal of the Korean Geosynthetics Society
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• v.23 no.3
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• pp.23-30
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• 2024

According to the method of settling the construction structure on the ground to keep the structure safe, the ground anchor method is divided into a load-distributing anchor and a general anchor. Recently, the application of load-distributed anchors, which show a large degree of recognition by anchors, is increasing in the field, but the problem of field applicability is also caused. The load-distributed anchor fixes the tensile force to each section of the lecture line and applies it, causing a problem of asymmetric loads in which the maximum tensile force size of each settlement site differs due to the length difference of the anchor body. Therefore, in this study, as a quality management method according to the asymmetric load of anchors, a mono-type load cell that can measure the load for each lecture line of a load-distributed anchor was developed, and the field applicability was analyzed by comparing and analyzing the measurement results of the existing multi-type load cell and mono-type load cell. As a result of the study, the multi-type load cell had no choice but to estimate the working load for each inner body, so it was impossible for the load-distributed anchor to manage it according to the generation of asymmetric loads for each lecture line. However, in the case of a mono-type load cell the load was measured for each inner body and for each lecture line, regardless of ground conditions and construction conditions, and thus the load value was measured for each lecture line, enabling safety management and construction management according to the occurrence of asymmetric loads.