• Journal of the Korean Society of Industry Convergence
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• v.14 no.1
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• pp.29-36
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• 2011

This study analyzed the convenience and productivity before and after adopting self-propelled power transportation devices to the harvest and transportation of fruit and vegetable products in the Gyeongbuk region, by applying the REBA and RULA techniques. In the REBA analysis, the work risk was low with 4~6 points before adoption which became 2~3 points after adoption. As for the RULA analysis, work loading appeared to have decreased with 6~7 points before adoption which became 3~4 points after adoption. The annual work time reduction was about 48~179 hours while labor costs were reduced to 364~1,345 thousand won annually. This indicated a labor cost reduction effect of about 10~15%. Therefore, the adopted self-propelled power transportation devices appeared to prevent musculo skeletal diseases of the human body and also improve productivity even after using it for long hours according to the REBA, RULA measures level.

• Proceedings of the KIPE Conference
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• 2014.11a
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• pp.33-34
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• 2014

In this paper, the inverter switch losses of BLDC motor for three types of PWM method and power devices was analyzed. When BLDC motor is driven at low currents, inverter switch losses for MOSFET is low because MOSFET operates like resistance. But, inverter switch losses for IGBT is higher than MOSFET due to its large turn-off losses. For low power inverter with MOSFET, the power losses of unified PWM is lower than that of unipolar and bipolar PWM.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.4
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• pp.286-290
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• 2015

Power system is composed of a number of power devices and equipment. This factor affects the power quality is also displayed very complicated and varied. The accurate measurement and analysis of the causes of power quality problems is difficult. In preparing for these issues, there are many difficulties. In this study, Power quality of A public establishment of Chungbuk province were measured and analyzed. Measurement results of the fifth harmonic current was very large. Accordingly, the harmonic reduction will be needed. This research will be utilized as fundamental data to improve power quality for power utility and customer.

• Journal of the Korea Society of Computer and Information
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• v.29 no.1
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• pp.195-209
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• 2024

The current road traffic signal controller developed in the 1990s has limitations in flexibility and scalability due to power supply problems, various communication methods, and hierarchical black box structures for various equipment and devices installed to improve traffic safety for road users and autonomous cooperative driving. In this paper, we designed a road traffic safety facilities equipment and devices integrated management system that can cope with the rapidly changing future traffic environment by solving the using direct current(DC) and power supply problem through the power over ethernet(PoE) technology and centralized data-driven control through message broker technology. In addition, a data-driven real-time control method for road traffic safety facilities equipment and devices operating based on time series data was implemented and verified.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.2
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• pp.117-125
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• 2016

In this paper, the inverter switch losses of BLDC motor for three types of PWM methods and power devices were analyzed. When the BLDC motor is driven at low currents, the inverter switch losses for MOSFET are low because MOSFET operates like resistance. However, the inverter switch losses for IGBT are higher than MOSFET due to its large turn-off losses. Moreover, synchronous rectification switching method is adaptable because MOSFET has 2-channel. So, MOSFET can be driven with more low impedance and losses. For low power inverter with MOSFET, the power losses of unified PWM are lower than that of unipolar and bipolar PWM. Proposed method and losses analysis results are verified by examination and simulation using Matlab/Simulink.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.07a
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• pp.673-674
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• 2023

도로교통의 안전 확보와 사고 예방을 목적으로 운전자나 보행자에게 필요한 정보를 제공하기 위해 경찰청에서 규격 또는 지침으로 제정하여 노변에 설치되는 교통안전시설 장치는 교통신호정보를 받기 위한 통신선과 함께 장치 구동을 위한 전원선을 개별로 시공해야 하기에 시공 비용의 절감과 함께 다종·다형의 장치에 대하여 통합적인 관제, 확장성, 유연성에 대응할 필요성이 제기되고 있다. 이에 본 논문에서는 이더넷 통신을 기반으로 전원 공급이 하나의 케이블로 가능한 이더넷 전원장치(PoE) 기술과 IoT 프로토콜인 MQTT를 이용하여 다종·다형의 교통안전시설 장치를 통합관제하고, 확장성과 유연성을 가지는 교통안전시설 장치 통합 시스템을 제안한다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.1
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• pp.184-190
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• 2014

Fuel cell power system, unlike conventional energy sources, converts chemical energy into electrical energy through electrochemical reaction of hydrogen and oxygen. In recent years, railway field as well as mobile fuel cell power system is being studying actively with development of hydrogen storage technologies. This paper presents the feasibility study on small-scale prototype electric railway vehicle application using fuel cell generation system. it is confirmed that proposed fuelcell-battery hybrid system shows good response characteristic about speed and torque based on design of parameter on system. Also as results of response for proposed system modeling, it show that powering mode and braking mode of system is controlled by switching devices of converters.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.95-98
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• 1998

Applying the magnetically levitated transportation system, which is noncontact bearing system, to solve the problems such as transformation of original form or flaw of iron plate caused by transportation of thin iron plate which required high quality as body of motor vehicle, materials of electronic devices etc.. Magnetic saturation phenomena caused by thickness of iron plate and gap size between magnets. In case of iron plate, the vibration mode will be considered since vibration occurs during transportation. In order to solve the problems caused by vibration, choose the levitation system method using numbers of magnet, magnetic saturation for thickness and length of iron plate with parameters in location and gap of magnet. In this paper, we will suggest the whole design technique of magnetically levitated transportation system, namely method of magnetic attraction and transportation system

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.3
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• pp.205-213
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• 2021

Due to the advantage of reducing the voltage applied to the switch semiconductor, the input series and output parallel combination is widely used in systems with high input voltage and large output current. On the other hand, the LLC converter is widely used as a high-efficiency power converter, and when connected by ISOP combination, there is a possibility that input voltage imbalance may occur due to a mismatch of passive devices. To avoid damaging the switching device, this study analyzed the DC-link voltage imbalance of a high-capacity supply using an ISOP LLC converter. In addition, the case where DC-link unbalance control was applied and the case not applied was analyzed respectively. Based on this analysis, an initial start-up algorithm was proposed to prevent input power semiconductor device damage due to DC-link over-voltage. The effectiveness of the proposed algorithm has been verified through simulations and experiments.

• The Journal of the Convergence on Culture Technology
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• v.9 no.2
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• pp.143-150
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• 2023

As Korea's per capita income increases, participation in various leisure activities to improve the quality of life of the disabled is encouraged. However, in order to participate in leisure activities, movement to the place where the leisure activities are performed must be preceded, so interest in means of transportation for leisure activities of the disabled is increasing. Since manual and electric wheelchairs have their respective disadvantages as means of transportation for leisure activities, interest in power assisting devices for wheelchairs combining the functions of electric wheelchairs with manual wheelchairs is increasing. In this study, the FDA approval process of wheelchair power-assistance products was investigated, and the characteristics of side-attached, front-attached, downward-attached, and rear-attached types of power assist devices for wheelchairs wheelchair in countries around the world were identified. These information will be of great use in helping the disabled and their assistants in Korea to choose the optimal product according to the patient's condition. More usability tests and clinical case studies are needed so that people with disabilities can choose a power assist device suitable for them.