• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.2
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• pp.137-142
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• 2021

A Photovoltaic power streetlight is a system that uses solar energy to charge a secondary battery and then uses it for night lighting through a lamp, and can be configured as a standalone or grid-connected type by installing an LED streetlight at the load end. The energy generated through the solar cell module can be charged to the secondary battery through the charge/discharge control device, and then the LED street light can be turned on and off by comparing the power generation voltage and the charging voltage according to the monitoring of solar radiation, or by setting a specific time after sunset or sunrise. Based on these contents, this paper designed and manufactured a simulated solar power streetlight for education using new and renewable energy utilization and storage functions. Using these educational equipment, students can 1) understand the flow of energy change using renewable energy including sunlight as electric energy, 2) understand new and renewable energy, and cultivate basic design and manufacturing application power of related products, 3) The use of new and renewable energy through power conversion and strengthening of practical training and analysis through hardware production can be instilled.

• Journal of Drive and Control
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• v.18 no.1
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• pp.1-8
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• 2021

This paper presents research on methods for the reduction of forklifts' noise level for the increased comfort and safety of its operator. A cooling fan with a high air volume flow rate installed in the forklift acts as an important design parameter which efficiently cools the heat exchanger system, helping to transfer internal heat from the engine room to the outdoors with both transmitted and diffracted opening noises. The cooling fan contributes significantly to both the forklift's emitted sound power and the operator room's noise level, thereby necessitating research on the forklift's reduction of acoustic power level and transmission. A noise analysis for various fan models with a biomimetic design based on eagle-wing geometry was conducted. In addition to the acoustic power generation, the aerodynamic performance of the cooling blade is also strongly influenced by the design of airfoil distribution, thereby requiring optimization. The cooling fans were fabricated and installed in the forklift in order to check the efficacy of the forklift engine's cooling, and the final version of the fan was measured for its ability to lower acoustic power level and cool the engine room. This study explains the aerodynamic and acoustic features of the designed fans with the use of BEM analysis and forklift test results.

• The Journal of the Korea Contents Association
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• v.21 no.2
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• pp.587-593
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• 2021

In this thesis, we will break away from the classic DDoS response system for large-scale denial-of-service attacks that develop day by day, and effectively endure intelligent denial-of-service attacks by utilizing artificial intelligence-based technology, one of the core technologies of the 4th revolution. A possible service model development plan was proposed. That is, a method to detect denial of service attacks and minimize damage through machine learning artificial intelligence learning targeting a large amount of data collected from multiple security devices and web servers was proposed. In particular, the development of a model for using artificial intelligence technology is to detect a Western service attack by focusing on the fact that when a service denial attack occurs while repeating a certain traffic change and transmitting data in a stable flow, a different pattern of data flow is shown. Artificial intelligence technology was used. When a denial of service attack occurs, a deviation between the probability-based actual traffic and the predicted value occurs, so it is possible to respond by judging as aggressiveness data. In this paper, a service denial attack detection model was explained by analyzing data based on logs generated from security equipment or servers.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.5
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• pp.287-296
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• 2020

The present study aims to improve the accuracy of the maneuvering simulations based on captive model test results. To derive the hydrodynamic coefficients in a self-propelled condition, a mathematical maneuvering model using a whole vehicle model was established. Captive model tests were carried out using the Vertical Planar Motion Mechanism (VPMM) equipment. A motor controller was used to control the constant propeller revolution rate during pure motion tests. The resistance tests, self-propulsion tests, static drift tests, and VPMM tests were performed in the towing tank of Seoul National University. When the vertical drift angle changes, the gravity load on the sensors were changed. The hydrodynamic forces were deduced by subtracting the gravity load from the measured forces. The hydrodynamic coefficients were calculated using the least-square method. The simulation of the turning circle test was compared with the free-running model test result, and the error of the turning radius was 8.3 % compared to the free-running model test.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.4
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• pp.595-602
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• 2021

Marine accidents are mostly caused by medium and small ships, and are continuously increasing. In this paper, we propose an architecture of the speech synthesis based automatic safety navigation support service providing system for small ships that equiped onboard systems compared with vessels. The main purpose of the system is to prevent marine accidents by providing synthesized voice safety messages to nearby ships. The safety navigation support service is operated by connecting GPS and AIS to synthesize voice safety messages, automatically broadcast through VHF. Therefore, we developed a data processing module, a staged risk analysis module, a voice synthesis safety message generation module, and a VHF broadcasting equipment control module, which are components of the system. In addition, we conducted laboratory-level and sea-trial demonstration tests using the developed the system, which verified usefulness of the proposed service.

• PNF and Movement
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• v.12 no.4
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• pp.243-248
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• 2014

Purpose: The transverse abdominis and themultifidus muscle are located in the core. They surround one's trunk and help in body stabilization. Specifically, they control spine articulation to maintain posture and balance. Therefore, weakened deep muscle in the trunk may cause spinal malalignment. This study aims to compare the correlation between the thickness of the transverse abdominis and the multifidus muscle and the spine alignment among college students in their 20s. Methods: This study measured the thickness of the transverse abdominis and the multifidus muscle of 42 healthy college students in their 20s using ultrasonic waves. The thickness of the muscle was measured for the length of the cross-section except for fascia. The thickness of the left and right muscles was measured, and the mean value was calculated. As the thickness of the transverse abdominis can increase because of pressure during exhalation, it was measured at the last moment of exhalation. Spinal alignment was measured by the kyphosis angle, lordosis angle, pelvic tilt, trunk inclination, lateral deviation, trunk imbalance, and surface rotation using Formetric III, which is a three-dimensional imaging equipment. They were measured for three times, and the mean values were calculated. The general characteristics of the subjects were analyzed using descriptive statistics. The correlations between each factor were analyzed using Pearson's correlation analysis. Results: The transverse abdominis showed asignificant correlation with trunk inclination (p<.05). The multifidus muscle showed a significant positive correlation with pelvic tilt and a negative correlation with surface rotation (p<.05). Conclusion: The thickness of transverse abdominis and the multifidus muscle appears to influence spinal alignment. Specifically, the multifidus muscle, which plays an important role on the sagittal plane, influences surface rotation, thus making it an important muscle for scoliosis patients. Therefore, a strengthening training program for the transverse abdominis and the multifidus muscle is necessary according to specific purposes among adults with spinal malalignment.

• Journal of Korea Society of Waste Management
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• v.35 no.7
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• pp.660-669
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• 2018

Domestic automotive shredder residue (ASR) recycling facilities must comply with 60% of the energy recovery criteria calculated by the waste control act, based on resource circulation of electrical and electronic equipment and vehicles. The method of calculating energy recovery criteria was newly enacted on November 6, 2017, and it has been judged that it is necessary to consider applicability. In this study, the energy recovery efficiency of 7 units was calculated by past and present calculation methods. Furthermore, this study attempts to find applicability and a method of increasing the energy recovery efficiency by taking advantage of available potentials. An analysis of the calculation results showed that the average values calculated by past methods, present methods, and the method that includes available potentials are 76.35%, 70.68%, and 78.24%, respectively. Therefore, the new calculation method for energy recovery efficiency is also applicable to domestic automotive shredder residue recycling facilities.

• Journal of Internet of Things and Convergence
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• v.7 no.1
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• pp.1-7
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• 2021

The IoT market continues to expand and grow, but the security threat to IoT devices is also increasing. However, it is difficult to apply the security technology applied to the existing system to IoT devices that have a problem of resource limitation. Therefore, in this paper, we present a service that can improve the security of IoT devices by presenting authentication and lightweight cryptographic algorithms that can reduce the overhead of applying security features, taking into account the nature of resource limitations of IoT devices. We want to apply these service to home network IoT equipment to provide security. The authentication and lightweight cryptographic algorithm application protocols presented in this paper have secured the safety of the service through the use of LEA encryption algorithms and secret key generation by users, IoT devices and server in the IoT environment. Although there is no difference in speed from randomly generating secret keys in experiments, we verify that the problem of resource limitation of IoT devices can be solved by additionally not applying logic for secret key sharing to IoT devices.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.12
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• pp.1673-1678
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• 2019

There are various networks and communication methods are used in industrial communication. Enterprises need to convert communications between industrial devices and networks for production line expansion, factory upgrades, network segmentation, and SI. This requires designers manufactured by many manufacturers to provide communication equipment for data or protocol conversion in order to connect and transmit various other mechanical devices to the network. This paper designed industrial communication gateway that can support the transformation of industrial communication protocol using multi-layered communication module. Industrial communication gateways have a structure that connects individual communication modules using RS485 communication to multiple layers. Each communication module consisted of analog and digital data card, LAN, and CAN-enabled card. The main board processor used Atmega micro-processor, and the RS485 slot was placed to have a multi-layer communication module structure. These additive layer type communication modules support analog and digital I/O functions and LAN and CAN for wide use in industrial communication control and monitoring.

• Journal of ILASS-Korea
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• v.25 no.4
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• pp.162-169
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• 2020

The worldwide focus on reducing the emissions, fuel and lubricant consumption in T-GDI engines is leading engineers to consider the crankcase ventilation and oil mist separation system as an important means of control. In today's passenger cars, the oil mist separation systems mainly use the inertia effect (e.g. labyrinth, cyclone etc.). Therefore, this study has investigated high efficiency cylinder head-integrated oil-mist separator by using a compact multi-impactor type oil mist separator system to ensure adequate oil mist separation performance. For this purpose, engine dynamometer testing with oil particle efficiency measurement equipment and 3D two-phase flow simulation have been performed for various engine operating conditions. Tests with an actual engine on a dynamometer showed oil aerosol particle size distributions varied depending on operating conditions. For instance, high rpm and load increases bot only blow-by gases but the amount of small size oil droplets. Submicron-sized particles (less than 0.5 ㎛) were also observed. It is also found that the impactor type separator is able to separate nearly no droplets of diameter lower than 3 ㎛. CFD results showed that the complex aerodynamics processes that lead to strong impingement and break-up can strip out large droplets and generate more small size droplets.