• International Journal of Internet, Broadcasting and Communication
• /
• v.10 no.3
• /
• pp.42-50
• /
• 2018

The majority of existing falling recognition techniques provide service by recognizing only that the falling occurred. However, it is important to recognize not only the occurrence of falling but also the situation before and after the falling, as well as the location of the falling. In this paper, we design and propose the falling notification service system to recognize and provide service. This system uses the acceleration sensor of the smartphone to recognize the occurrence of a falling and the situation before and after the falling. In order to check the location of falling, GPS sensor data is used in the Google Map API to map to the map. Also, a crosswalk map converted into grid-based coordinates based on the longitude and latitude of the crosswalk is stored, and the locations before and after falling are mapped. In order to reduce the connection speed and server overload for real-time data processing, fog computing and cloud computing are designed to be distributed processing.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.39 no.3
• /
• pp.232-239
• /
• 1990

A new algorithm is suggested to solve the optimal reactive power and voltage control (optimal VAR control) problem. The model minimizes the real power losses in the system. The constraints include the reactive power limits of the generators, limits on the bus voltages and the operating limits of control variables-the transformer tap positions generator terminal voltages and switchable reactive power sources. The method presented herein, using a newly developed Jacobian decomposition method, employs linearized sensitivity relationships of power systems to establish both the objective function for minimizing the system losses and the system performance sensitivities relating dependent and control variables. The algorithm consists of two modules, i.e. the Q-V module for reactive power-voltage control, and load flow module for computational error adjustments. In particular the acceleration factor technique is introduced to enhance the convergence property in Q-V module. The combined use of the afore-mentioned two modules ensures more effective and efficient solutions for optimal reactive power dispatch problems. Results of the application of the method to a sample system and other worst-case systems demonstrated that the algorithm suggested herein is compared favourably with conventional ones in terms of computation accuracy and convergence characteristics.

• Journal of the Institute of Convergence Signal Processing
• /
• v.20 no.1
• /
• pp.57-62
• /
• 2019

In this paper, oneM2M based data monitoring and acquisition system is designed and implemented to measure and transmit the voltage, current, temperature, acceleration and vibration of the motor. The proposed system can detect electrical faults (overcurrent, reverse phase, phase loss, ground fault) and mechanical faults (MC counter, motor operation time, bearing and winding temperature, motor speed, insulation resistance). The system consists of sensor data collection, web server, php, database, wired/wireless communication system. The insulation resistance and the motor speed were measured, and the experimental results were similar for both the test resistance value and the reference input value.

• Journal of the Korean Society of Industry Convergence
• /
• v.22 no.6
• /
• pp.637-647
• /
• 2019

In this study, we analyzed seismic behavior of reinforced earth retaining wall through the model test in order to characterize the behavior of reinforced earth retaining wall during earthquake. A scale model test was performed based on similitude ratio in accordance with law of similitude due to time and financial constraints on real scale modeling experiments. Seismic resistance characteristics of each seismic waves were analyzed by assessing the variations measured through excitation of the excited acceleration of 0.05g, 0.1g, 0.15g, and 0.2g. The results of this study, it would be important to obtain reasonable and abundant data on ground properties and seismic design in preparation for earthquakes when assessing the safety of block type reinforced earth retaining wall confined to model experiment. Acquisition of those data and systematic analytical techniques are considered likely to have a significant effect on the decrease of structure damage caused by earthquakes in Korea which has recently witnessed frequent occurrence of earthquakes.

• Journal of the Korean Society of Industry Convergence
• /
• v.23 no.4_2
• /
• pp.653-659
• /
• 2020

In this study, seismic verification of the bellows used in the plant field was conducted. The pressure used in the analysis was analyzed by applying the design pressure of 15.7bar. For the seismic analysis, the natural frequency of the bellows system was obtained and the stability of the system was evaluated by static seismic analysis comparing the lowest order natural frequency with the dominant frequency of 33 Hz. The material of the bellows system is STS304, and the safety factor is obtained in comparison with the allowable stress. For the seismic analysis, the design response spectrum was prepared and the maximum acceleration was applied to the static seismic analysis and the stability of the entire system was confirmed. Compared to the structural analysis results, the maximum stress of the bellows system increased by about 16.4% and the maximum strain increased by about 3 times when seismic analysis was performed.

• Journal of the Institute of Convergence Signal Processing
• /
• v.19 no.4
• /
• pp.186-191
• /
• 2018

As influence of the 4th industry is growing with development of information society more electronic devices and sensor are used in the field. As this is the case, importance of signal processing during data transfer is rising Furthermore, the need for technology to remove noise caused by various reasons and to stabilize sensor output is growing as well. This research suggests digital filter algorithm that efficiently remove noise by stabilizing output of accelerating sensor. The standard value of this algorithm is calculated by applying Gaussian coefficient. To maintain its feature, final output is obtained by subtracting weight depending on variance from standard value For its evaluation, it is compared with other protocols and its function is checked through output features.

• Journal of the Institute of Convergence Signal Processing
• /
• v.21 no.3
• /
• pp.142-147
• /
• 2020

The Internet of Things is valuable as a means of solving social problems such as personal, public, and industrial. Recently, the application of IoT technology to the healthcare industry is increasing. It is important to ensure reliability and security in IoT-based healthcare services. Communication protocols, wireless transmit/receive techniques, and reliability-based message delivery are essential elements in IoT healthcare devices. The system was designed and implemented to measure body temperature and activity through body temperature and acceleration sensors and deliver them to the oneM2M-based Mobius platform.

• Journal of the Korean Society of Industry Convergence
• /
• v.25 no.5
• /
• pp.757-764
• /
• 2022

Recently the car tuning has become a trailblazing and creative culture that expresses the personality of the owner. In this paper, the "Car-Vatar", which is the compound word formed from the words "Car" and "Avatar", has been developed to investigate car tuning on the metaverse engineering platform. The Car-Vatar has been developed as a web-based vehicle dynamic simulation service for providing information about car tuning. That has been focused on investigating diverse vehicular performances, such as acceleration, braking, handling and fuel efficiency, according to the tuning vehicles and tuning parts on the virtual engineering platform. The Car-Vatar platform has provided two major services; one is real-time 3D tuning information system for the dress-up and performance-up tuning parts, the other is diverse vehicle dynamics system for the performance-up tuning parts. To check the validation of the Car-Vatar platform, the comparison between virtual simulation results and driving test results has been discussed on various driving environments.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.21 no.9
• /
• pp.71-77
• /
• 2022

In times of war or emergencies, weapon systems, such as radars, must receive stable power. This can be achieved using improved onboard portable power systems made of steel containers. However, a breakdown can occur in the event of random vibration during transportation via a vehicle or train. Electrical-power shortages or restrictions pose a significant threat to security. In this study, Composite Wheeled Vehicle(CWV) data and rail cargo data with Acceleration Spectral Density(ASD), specified in MIL-STD-810H METHOD 514.8, were interpreted as input data of the three-axis random vibration method using ANSYS 19.2. Modal analysis was performed up to 500 Hz, and deformations in modes 1 to 117 were calculated to utilize all ASD data. The maximum equivalent stress in the three-axis direction was obtained using a random vibration analysis. Similarly, the margin of safety was calculated using the derived equivalent stress and material properties. Overall, the analysis verified that the portable container designed for the power supply system satisfied the required vibration demands.

• Journal of Advanced Technology Convergence
• /
• v.2 no.3
• /
• pp.1-7
• /
• 2023

The problem of climate change is intensifying around the world, and the increasing use of fossil fuels is causing a variety of problems. In particular, interest in renewable energy is increasing due to the acceleration of carbon neutrality policies. In this study, we utilized SCOPUS DB to identify trends in renewable energy research. We obtained 1,353 data for which abstracts were available and performed data preprocessing to analyze them. Topic modeling analysis showed that renewable and energy were the most important keywords. In addition, electricity, solar, wind, etc. were analyzed as important keywords. Through the results of this study, it is expected that practitioners of renewable energy-related companies can utilize the research trends related to renewable energy in practice.