• Journal of the Korean Society of Marine Environment & Safety
• /
• v.25 no.6
• /
• pp.802-808
• /
• 2019

DC motors are used extensively on shipboard, including as the ship's winch operating motor, owing to their simple speed control and excellent output torque characteristics. Moreover, they were used as propulsion motors in the early days of electric propulsion ships. However, mechanical rectifiers, such as brushes, used in DC motors have certain disadvantages. Hence, brushless DC (BLDC) motors are increasingly being used instead. While the electrical characteristics of both types of motors are similar, BLDC motors employ electronic rectifying devices, which use semiconductor elements, instead of mechanical rectifying devices. The inverter system for driving conventional BLDC motors uses a two-phase excitation method so that the waveform of the back electromotive force becomes trapezoidal. This causes harmonics and torque ripple in the phase current switching period in which the winding wire through which the current flows is changed. Researchers have studied and presented various methods to reduce the harmonics and torque ripple. This study applies a cascaded H-bridge multilevel inverter, which implements a proportional-integral speed current controller algorithm in the driving circuit of the BLDC motor for electric propulsion ships using a power analysis program. The simulation results of the modeled BLDC motor show that the driving method of the proposed BLDC motor improves the voltage waveform of the input side of the motor and remarkably reduces the harmonics and torque ripple compared with the conventional driving method.

• International Journal of Advanced Culture Technology
• /
• v.8 no.2
• /
• pp.58-67
• /
• 2020

In this paper, the maintenance training manual of EV vehicle was produced by utilizing digital twin technology and various sensors such as IR-based light house tracking and head tracker. In addition, through digital twin technology and VR to provide high immersiveness to users, sensory content creation technology was secured through animation and effect realization suitable for EV vehicle maintenance situation. EV vehicle maintenance training manual is 3D engine programming and real-time creation of 3D objects and minimization of screen obstacles and selection of specific menus in virtual space in the form of training simulation. In addition, automatic output from the Head Mount Display (HUD), EV vehicle maintenance and inspection, etc., user can easily operate content was produced. This technology development can enhance immersion to users through implementation of detailed scenarios for maintenance / inspection of EV vehicles" and 3D parts display by procedure, realization of animations and effects for maintenance situations. Through this study, familiarity with improving the quality of education and safety accidents and correct maintenance process and the experienced person was very helpful in learning how to use equipment naturally and how to maintain EV vehicles.

• Proceedings of the KIEE Conference
• /
• 2005.07d
• /
• pp.2824-2826
• /
• 2005

국내 전력소비량은 1961년 전원 개발을 본격적으로 추진한 이래 세계12위 규모로 성장하였다. 그러나 전력사용 증가에 따른 전기화재, 감전 및 설비사고 등 전기재해 역시 계속 증가하여 전체 화재사고 중 전기로 인한 화재비율이 선진국과 비교하여 크게 높은 실정이다. 본 연구에서는 전기안전에 관한 국민의식 제고를 목표로 전기안전 교육을 위한 애니메이션(3D 및 2D 프로그램)을 제작하여 전기 안전문화를 조성하는 홍보매체로 활용할 수 있도록 연구를 수행하였다.

• Proceedings of the KAIS Fall Conference
• /
• 2006.05a
• /
• pp.324-326
• /
• 2006

국내 전력소비량은 1961년 전원 개발을 본격적으로 추진한 이래 세계12위 규모로 성장하였다. 그러나 전력사용 증가에 따른 전기화재, 감전 및 설비사고 등 전기재해 역시 계속 증가하여 전체 화재 사고 중 전기로 인한 화재비율이 선진국과 비교하여 크게 높은 실정이다. 본 연구에서는 전기안전에 관한 국민의식 제고를 목표로 전기안전 교육을 위한 3D애니메이션프로그램을 제작하여 전기 안전문화를 조성하는 홍보매체로 활용할 수 있도록 연구를 수행하였다.

• Geomechanics and Engineering
• /
• v.28 no.6
• /
• pp.637-644
• /
• 2022

Loess soils are unsaturated and widely distributed in the northwest zone in China. Many steep slope of unsaturated are observed are observed to be naturally stable. However, a low factor of safety (FoS) for these slopes would be computed from the slope stability analysis following local code practices. It seems that the analyzed results following the local code practices do not agree with the real condition as observed in the field. It is commonly known that soil suction plays an important role in slope stability due to a higher shear strength of the unsaturated soil as compared with that of the saturated soil. In this paper, it is observed that the computed FoS can also be affected by unsaturated unit weight of the soil. However, the effect of unsaturated unit weight of the soil on the slope stability is commonly ignored in engineering practice. Therefore, both the effects of shear strength and unit weight of the unsaturated soil on the computed FoS of unsaturated soil slope are investigated in this study. It is observed that the unsaturated unit weight of soil on the computed FoS increases with increase in slope angle. It is also observed that the effects of the unsaturated shear strength and unsaturated unit weight on the computed FoS are more significant than the effect of 3D analyses compared to the 2D analyses on the FoS.

• Proceedings of the KSR Conference
• /
• 2009.05a
• /
• pp.1229-1234
• /
• 2009

The rolling stocks of KORAIL are KTX, Saemaulho Multiple Unit(PP), New Electrical Locomotive(DL), Electrical Locomotive(EL), Diesel Locomotive, Metropolitan Commuter Train(CDC), VVVF and Resistance Controlled Multiple Unit, etc. EMU with the maximum speed of 150km/h is under the test run at the moment. Electrical Multiple Units for mainlines with 180km/h speed are supposed to be introduced as a substitute for Saemaulho Multiple Unit which is scheduled to be out of service. But the specification standard for the control board design of train driver's cab does not exist and there is no a study for layout and type of controlling device with driver's ergonomical approach. That's why the types of controller and operating are different from rolling stocks, which has high possibility of driver's human error and needs education whenever a new car comes in. Based on the opinion poll of drivers, design specification of safety engineering and ergonomics for controlling devices and safety facilities can improve exact control for devices and deal quickly with an emergency so as to improve rolling stock safety and operational efficiency.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.20 no.3
• /
• pp.47-58
• /
• 2021

Recently, personal mobility (PM)-related complaints and PM accidents have increased as the number of users soars due to growth in the domestic PM market and the emergence of a number of electric scooter-sharing services. As a result, the need for PM education and practice spaces is emerging as a way to reduce accidents caused by poor PM manipulation and operation. In this study, we analyze the relevant conflict factors in order to come up with a systematic operation and activation plan for PM, and as an alternative, we review and propose how to operate a PM playground and test zone. It is expected that basic data collection and analysis of rudimentary driver behavior through PM playground operations will improve users' operational safety, and various conflicts of interest between users and non-users will be resolved by installing facilities to secure their safety.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.13 no.5
• /
• pp.1135-1144
• /
• 2018

An electric wheelchair used to be utilized as a piece of equipment for the disabled and the elderly in the past, but the recent changes to its functions and forms have made it available across various fields and purposes. In this paper, we propose a continuous track type of electric wheelchair prototype to be used in various fields and environments and a monitoring system to control it. A frame stress design was applied to improve its stability during driving compared with the previous wheelchairs. In addition, we provide a convenience for free and easy operation of them using the App. based on android. A monitoring system based on C# was also added to control a large number of electric wheelchairs. As a result of the implementation and performance evaluation, the von Mises stress value was measured 4.401% within the normal range through five times of stress interpretations, and its accuracy of communication for system manipulation was recorded about 98.75%, which means that it has been proven to be safer than the previous wheelchairs.

• Fire Science and Engineering
• /
• v.30 no.3
• /
• pp.62-66
• /
• 2016

There have been happening small and big fires due to the various causes in the thermal power plants which are the high risk buildings with the high possibility of big sizes of accidents, so the people in the power plants distribute the workers "the site action manuals in thermal power plants" and try to minimize the rate of disasters like fires through the regular education and training. However, in the Five Thermal Power Plants in Korea, there are no the standard of "the site action manuals" and Furthermore, the present educational manuals are mostly the hard copies with poor readability. So the standardization of the manuals are definitely needed. Therefore, in this research, we proceed the standardization of the manuals for the five areas of the site action manual s in the thermal power plants which are oil fires, electric fires, building fires, facility fires and gas leaking reaction SOP to improve the reaction power on the disasters in the power plants which are the national significant infrastructures, thus by using the manual, we propose the safety education contents for the thermal power plants based on the visualization technology using story-viewing method to complement the hard copy type disaster manuals.

• Annals of Clinical Neurophysiology
• /
• v.20 no.2
• /
• pp.66-70
• /
• 2018

Electrodiagnostic studies such as nerve conduction studies (NCS) and needle electromyography (EMG) provide important and complementary information for evaluating patients with suspected neuromuscular disorders. NCS and needle EMG are reasonably safe diagnostic investigations and are generally associated with only mild transient discomfort when performed by experienced physicians. However, there is the risk of complications in some patients, because NCS involve the administration of electric current and EMG involves inserting a needle percutaneously into muscle tissue. This article reviews the potential risks of NCS and needle EMG.