• Structural Engineering and Mechanics
• /
• v.77 no.4
• /
• pp.441-461
• /
• 2021

Reinforced concrete (RC) columns are crucial in building structures and they are of higher vulnerability to terrorist threat than any other structural elements. Thus it is of great interest and necessity to achieve a comprehensive understanding of the possible responses of RC columns when exposed to high intensive blast loads. The primary objective of this study is to derive analytical formulas to assess vulnerability of RC columns using an advanced numerical modelling approach. This investigation is necessary as the effect of blast loads would be minimal to the RC structure if the explosive charge is located at the safe standoff distance from the main columns in the building and therefore minimizes the chance of disastrous collapse of the RC columns. In the current research, finite element model is developed for RC columns using LS-DYNA program that includes a comprehensive discussion of the material models, element formulation, boundary condition and loading methods. Numerical model is validated to aid in the study of RC column testing against the explosion field test results. Residual capacity of RC column is selected as damage criteria. Intensive investigations using Arbitrary Lagrangian Eulerian (ALE) methodology are then implemented to evaluate the influence of scaled distance, column dimension, concrete and steel reinforcement properties and axial load index on the vulnerability of RC columns. The generated empirical formulae can be used by the designers to predict a damage degree of new column design when consider explosive loads. With an extensive knowledge on the vulnerability assessment of RC structures under blast explosion, advancement to the convention design of structural elements can be achieved to improve the column survivability, while reducing the lethality of explosive attack and in turn providing a safer environment for the public.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.41 no.6
• /
• pp.627-635
• /
• 2021

The fire damage and structural performance of a steel-concrete composite superstructure under a highway bridge exposed to fire loading was evaluated. To enhance the accuracy and efficiency of the numerical analysis, a proposed fluid-structure interaction fire analysis method was implemented in Ansys Fluent and Ansys Mechanical. The temperature distribution and performance evaluation of the steel-concrete composite superstructure according to the vertical distance from the fire source to the bottom flange were evaluated using the proposed analysis method. From the analysis, the temperature of the concrete slab and the bottom flange of the steel-concrete composite superstructure exceeded the critical temperature. Also, when the vertical distance from the fire source was 13 m or greater, the fire damage of the steel-concrete composite superstructure was found to within a safe limit.

• The Journal of Korea Robotics Society
• /
• v.17 no.2
• /
• pp.198-208
• /
• 2022

In this paper, an autonomous driving system is implemented for the Segye AI Robot Race Competition that multiple vehicles drive simultaneously. By utilizing the ERP42-racing platform, RTK-GPS, and LiDAR sensors provided in the competition, we propose an autonomous driving system that can drive safely and quickly in a road environment with multiple vehicles. This system consists of a recognition, judgement, and control parts. In the recognition stage, vehicle localization and obstacle detection through waypoint-based LiDAR ROI were performed. In the judgement stage, target velocity setting and obstacle avoidance judgement are determined in consideration of the straight/curved section and the distance between the vehicle and the neighboring vehicle. In the control stage, adaptive cruise longitudinal velocity control based on safe distance and lateral velocity control based on pure-pursuit are performed. To overcome the limited experimental environment, simulation and partial actual experiments were conducted together to develop and verify the proposed algorithms. After that, we participated in the Segye AI Robot Race Competition and performed autonomous driving racing with verified algorithms.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.50 no.11
• /
• pp.763-770
• /
• 2022

In an environment where multiple drones are operated, collisions can occur when path points overlap, and collision avoidance in preparation for this is essential. When multiple drones perform multiple tasks, it is not appropriate to use a method to generate a collision-avoiding path in the path planning phase because the path of the drone is complex and there are too many collision prediction points. In this paper, we generate a path through a commonly used path generation algorithm and propose a collision avoidance method using speed profile optimization from that path segment. The safe distance between drones was considered at the expected point of collision between paths of drones, and it was designed to assign a speed profile to the path segment. The optimization problem was defined by setting the distance between drones as variables in the flight time equation. We constructed the constraints through linearize and convexification, and compared the computation time of SQP and convex optimization method in multiple drone operating environments. Finally, we confirmed whether the results of performing convex optimization in the 20 drone operating environments were suitable for the multiple drone operating system proposed in this study.

• Journal of Veterinary Science
• /
• v.24 no.1
• /
• pp.12.1-12.10
• /
• 2023

Background: Arthroscopic exploration of ventromedial part of canine coxofemoral joint is limited in conventional dorsal approach. Objectives: We evaluated the efficacy of a medial arthroscopic approach to the coxofemoral joint of dogs by analyzing the joint visible area and performing a safety analysis. Methods: Arthroscopic approaches to the coxofemoral joint were made in five cadavers using a traditional (dorsal) and novel (medial) approach. Three observers scored the visible area of images and videos of the acetabulum and femur. A safety analysis was performed via dissection of the medial hind limb. The distance between neurovascular structures and arthroscopic portals was measured. Results: The acetabulum was more visible in the dorsal than in the medial approach, with mean visualization scores of 16 ± 0.00 and 11.83 ± 1.26, respectively. The medioventral side of the femur was significantly more visible in the medial than in the dorsal approach, with mean visualization scores of 3.9 ± 0.99 and 6.93 ± 0.58, respectively. Safety analysis confirmed the medial portal site was safe, provided that the surgeon has comprehensive knowledge of the joint. The minimum distance from the arthroscopic medial portals to the nearest neurovascular structures was 2.5 mm. Conclusions: A medial arthroscopic approach to the canine coxofemoral joint has potential clinical application. Dorsal and medial approaches differ significantly and have distinct purposes. The medial approach is useful to access the ventromedial joint, making it an eligible diagnostic method for an arthroscopic evaluation of this area.

• Journal of the Institute of Convergence Signal Processing
• /
• v.23 no.2
• /
• pp.91-96
• /
• 2022

At the current camera-based technology level, sensor-based basic life pattern recognition technology has to suffer inconvenience to obtain accurate data, and commercial band products are difficult to collect accurate data, and cannot take into account the motive, cause, and psychological effect of behavior. the current situation. In this paper, radar technology for life pattern recognition is a technology that measures the distance, speed, and angle with an object by transmitting a waveform designed to detect nearby people or objects in daily life and processing the reflected received signal. It was designed to supplement issues such as privacy protection in the existing image-based service by applying it. For the implementation of the proposed system, based on TI IWR1642 chip, RF chipset control for 60GHz band millimeter wave FMCW transmission/reception, module development for distance/speed/angle detection, and technology including signal processing software were implemented. It is expected that analysis of individual life patterns will be possible by calculating self-management and behavior sequences by extracting personalized life patterns through quantitative analysis of life patterns as meta-analysis of living information in security and safe guards application.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.46 no.1
• /
• pp.15-22
• /
• 2023

An Ant Colony Optimization Algorithm(ACO) is one of the frequently used algorithms to solve the Traveling Salesman Problem(TSP). Since the ACO searches for the optimal value by updating the pheromone, it is difficult to consider the distance between the nodes and other variables other than the amount of the pheromone. In this study, fuzzy logic is added to ACO, which can help in making decision with multiple variables. The improved algorithm improves computation complexity and increases computation time when other variables besides distance and pheromone are added. Therefore, using the algorithm improved by the fuzzy logic, it is possible to solve TSP with many variables accurately and quickly. Existing ACO have been applied only to pheromone as a criterion for decision making, and other variables are excluded. However, when applying the fuzzy logic, it is possible to apply the algorithm to various situations because it is easy to judge which way is safe and fast by not only searching for the road but also adding other variables such as accident risk and road congestion. Adding a variable to an existing algorithm, it takes a long time to calculate each corresponding variable. However, when the improved algorithm is used, the result of calculating the fuzzy logic reduces the computation time to obtain the optimum value.

• Archives of Plastic Surgery
• /
• v.50 no.5
• /
• pp.446-451
• /
• 2023

Background Elderly patients often have complications of blepharoptosis surgery that can result in the appearance or exacerbation of superficial punctate keratopathy (SPK). However, postoperative changes to SPK status have not been previously reported. We used subjective assessment of symptoms and measurement of SPK scale classification to investigate the safety and efficacy of blepharoptosis surgery in elderly patients. Methods Included in this prospective study were 22 patients (44 eyes) with bilateral blepharoptosis that underwent surgery. Patients comprised 8 males and 14 females with a mean (±standard deviation) age of 75.7 ± 8.2 years (range: 61-89). Blepharoptosis surgery consisted of transcutaneous levator advancement and blepharoplasty including resection of soft tissue (skin, subcutaneous tissue, and the orbicularis oculi muscle). Margin reflex distance-1 (MRD-1) measurement, a questionnaire survey of symptoms and SPK scale classification, was administered preoperatively and 3 months postoperatively for evaluation. Results The median MRD-1 was 1 mm preoperatively and 2.5 mm postoperatively, representing a significant postoperative improvement. SPK area and density scores were found to increase when the MRD-1 increase was more than 2.5 mm with surgery. All 10 items on the questionnaire tended have increased scores after surgery, and significant differences were observed in 7 items (poor visibility, ocular fatigue, heavy eyelid, foreign body sensation, difficulty in focusing, headaches, and stiff shoulders). Conclusion Blepharoptosis surgery was found to be a safe and effective way to maintain the increase in MRD-1 within 2.0 mm. Despite the benefits, surgeons must nonetheless be aware that blepharoptosis surgery is a delicate procedure in elderly people.

• Anatomy and Cell Biology
• /
• v.56 no.1
• /
• pp.32-38
• /
• 2023

The Galenic venous system plays a vital role in the drainage of blood from deeper parts of the brain. This venous system is contributed by many major veins. These veins are located closer to the pineal gland making the surgical approach in this region difficult. Any accidental injury or occlusion of the vein of Galen could lead to devasting results. Thus, studying the dimensions of the vein of Galen is more important. Hence, we aimed to evaluate the morphometry and trajectory to the vein of Galen. About 100 computed tomographic venography records were evaluated and the length, diameter of vein of Galen, angle between straight sinus and vein of Galen and distance from internal occipital protuberance and roof of fourth ventricle to vein of Galen were studied. The mean length and diameter of vein of Galen were 9.8±2.7 and 4.08±1.04 respectively. The mean angle between straight sinus and vein of Galen was 64.2°. The mean distance between external occipital protuberance and roof of fourth ventricle to vein of Galen were 52±6.9 and 33.3±4.5 respectively. No significant morphometric differences were observed between the age groups as well as between the sexs. The results obtained from this study may be helpful for the neurosurgeons in better understanding of the anatomy of the Galenic venous system and to adopt a safe surgical approach to improve the efficacy of the surgeries of the pineal gland and also in the region of vein of Galen.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.9
• /
• pp.6274-6281
• /
• 2015

Radio-based train control system has driving headway shortening effect by real-time train interval control using two-way radio communication between onboard and wayside systems, and reduces facility investment because it does not require any track-circuit. Automatic train protection(ATP), the most significant part of the radio-based train control system, makes sure a safe distance between preceding and following trains, based on real-time train location tracing. In this paper, we propose the overall ATP train interval control algorithm to control the safe interval between trains, and preprocessing-based speed profile calculation algorithm to improve the processing speed of the ATP. The proposed speed profile calculation algorithm calculates the permanent speed limit for track and train in advance and uses as the most restrictive speed profile. If the temporary speed limit is generated for a particular track section, it reflects the temporary speed limit to pre-calculated speed profile and improves calculation performance by updating the speed profile for the corresponding track section. To evaluate the performance of the proposed speed profile calculation algorithm, we analyze the proposed algorithm with O-notation and we can find that it is possible to improve the time complexity than the existing one. To verify the proposed ATP train interval control algorithm, we build the train interval control simulator. The experimental results show the safe train interval control is carried out in a variety of operating conditions.