• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.237-246
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• 2019

The Electro-Mechanical Brake (EMB) is the next generation braking system for automobiles and railway vehicles. Current brake systems for high-speed trains generate a braking force using a pneumatic cylinder, but EMB systems produce that force through a combination of an electric motor and a gear. In this study, an EMB operation mechanism capable of generating a high braking force was proposed, and structural and vibration analyses of the gears and shafts, which are the core parts of the mechanisms, were performed. Dynamic structural analysis confirmed that the maximum stress in the analysis model was within the yield strength of the material. In addition, the design that maximizes the diameter of the motor shaft was found to be advantageous in strength, and large shear stress could be generated in the bolt fixing the gear and eccentric shaft. In addition, a test apparatus that can reproduce the mechanism of the analytical model was fabricated to measure the strain of the fixed bolt part, which is the most vulnerable part. The strain measurement results showed that the error between the analysis and measurement was within 10%, which could verify the accuracy of the analytical model.

• Journal of IKEEE
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• v.18 no.3
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• pp.335-340
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• 2014

Recently, LED (Light Emitting Diode) becomes to be useful to apply for the lightening sources in electric systems and the lightening equipment since the power is less consumed with high efficiency, and the size and the weight of LED are small and light, respectively. The LED is controlled with constant current and SMPS (Switching Mode Power Supply). It is necessary for the LED manufacturer to secure the fundamental technology of designing LED chip, and to study the methodology to improve the power factor (PF) and to design the operational circuit for the development of LED to reduce the power loss in the application of LED lightening. The direct AC (Alternating Current) LED driving circuit, HV9910, is widely used in the industry field. In this paper, it is to evaluate the improved methodology for the power factor and efficiency through simulations when PFC (Power Factor Correction) and Noise Filter are added to HV9910.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.731-736
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• 2011

A pneumatic driving solenoid valve operates pneumatic control devices by opening/closing operating flow passage when the command is given by control system for the liquid-propellant feeding system of space launch vehicle. The simulation model of pneumatic driving solenoid valve is designed with AMESim to verify the designs and evaluate the dynamic characteristics and pneumatic behaviors of valve. To validate a valve simulation model, the simulation results of their operating durations of valve by AMESim analysis are compared with the results of experiments. In addition, the results of internal flow simulation with FLUENT are utilized to improve the accuracy of valve-modeling. Using the model, we analyze performance of valve; opening/closing pressure, operating time on various design factors; shape of control valve seat, drainage seat, rate of sealing diameter, volume of control cavity. This study will serve as one of reference guides to enhance the developmental efficiency of ventilation-relief valves with the various operating conditions, which shall be used in Korea Space Launch Vehicle-II.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.2
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• pp.26-37
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• 2012

In this study, a power driver for actuating PVDF film that has the characteristic of dramatic impedance change caused by size and operating frequency variation was developed to dehyance rate of dredged sediment. In order to supply maximum energy to the PVDF film, a full-bridge circuit implemented using IGBT with a R-L-PVDF film impedance matching circuit was designed and constructed. the dehydration capabilities of the PVDF film actuated by the developed driver cleary was tested for dredged sediment. It was found that the PVDF film actuated by the developed driver cleary enhanced dehydration, avout three times faster during the first 3 minutes, compared to natural dehydration. The result of the experiment confirmed that the developed power driver for actuating Pvdf film could be used effectively for dehydration of dredged sediment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.6
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• pp.731-738
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• 2013

This paper describes a fault-tolerant driving control strategy for an independent steer-by-wire system in sixwheel-drive/six-wheel-steering vehicles. An algorithm has been designed to realize vehicle maneuverability that is as close as possible to that of non-faulty vehicles by inducing high slip ratio of the wheel through a faulty steer-by-wire system in order to reduce the lateral tire force, which is resistant to the yaw motion. Considering the transition of the longitudinal tire force of a wheel with a faulty steer-by-wire component, the longitudinal tire forces are optimally distributed to the other wheels. Fault-tolerant driving performance has been investigated via computer simulations. Simulation studies show that the proposed algorithm can significantly improve the maneuverability of a vehicle with a faulty steer-by-wire system as compared to the optimal traction distribution method.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.5
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• pp.570-576
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• 2012

In this research a moving platform for a mobile robot which can run with upright posture is proposed. It is able to stand with standing arms and run uprightly based on an inverted pendulum mechanism. Conventional mobile robots generally may equip 4 wheels or 3 wheels including a caster and have good statistic stability. They need a steering mechanism to choose which way to go since they have a square or rectangular configuration with multiple wheels. When a mobile robot meets a sharply perpendicular and narrow crossroad, it may need a special steering scheme such as going forward and backward repeatedly or it sometimes cannot even pass through the crossroad because of its size. The proposed moving platform for a mobile robot changes to a upright posture which has a small planar area and is able to pass through the crossroad. We propose a moving platform for a mobile robot with a inverted pendulum mechanism and standing arms which can make the mobile robot upright.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.4
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• pp.105-113
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• 1995

A mechanical actuator to generate adjustable force ants its active control algorithm to minimize ship structural vibration are developed. The algorithms comprise initial algorithm which determines optimal phase and force magnitude of the actuator using the variation of vibration response according to the phase difference between the main engine and the actuator, and regulating algorithm which performs continuous optimal control to track the change of the engine speed. This control system can be applied without any prior identification for the dynamic characteristics of the controlled structure. In the control experiments for the deckhouse structural vibration of a 300,000 DWT crude oil carrier and a 2,270 TEU container carrier, the developed system showed good performance to reduce the vibration levels to $1/2{\sim}1/6$ of the uncontrolled levels.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.17 no.5
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• pp.302-312
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• 2024

In this paper, I proposed an independent control system for a driving motor that directly connects and controls two motors to the rear driving wheel. Typical electric vehicles have used differential gears to distribute and transmit the output from one driving motor to each rear wheel. However, the differential gear is one of the very heavy parts in the electric vehicle, and causes a lot of power loss in the process of transmitting power. Therefore, I want to install two motors to control each wheel directly and remove the differential gears. Each rear wheel is independently controlled by two motors to suit the driving situation of the vehicle. When the vehicle is going straight, the controller synchronizes the rotational speed of the two wheels to make the vehicle go straight, and when the vehicle is turning, the vehicle can rotate by varying the rotational speed of each rear wheel according to the steering angle and driving speed of the vehicle. And since each rear wheel is controlled independently, it is expected that it can be controlled to perform the function of the limited slip differential through a program in a situation where the gripping force of one driving wheel decreases.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.292-303
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• 2004

The previous exponential experiment system has been improved for the automatical and accurate axial movement of the neutron source and detector with attaching the automatical control system which consists of a Programmable Logical Controller(PLC) and a stepping motor set. The automatic control program which controls MCA and PLC consistently has been also developed on the basis of GENIE 2000 Library. The exponential experiments have been carried out for Kori 1 unit spent fuel assemblies, Cl4, Jl4 and G23, and Kori 2 unit spent fuel assembly, J44, using the improved systematical measurement system. As the results, the average exponential decay constants for 4 assemblies are determined to be 0.1302, 0.1267, 0.1247, and 0.1210, respectively, with the application of Poisson regression.

• Progress in Medical Physics
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• v.10 no.1
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• pp.9-15
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• 1999

The oxygen saturation of blood can be measured by the difference absorption in optical spectra of Hb and Hb0$_2$, as the well known previous study. In this study we developed the non-invasive oxygen measurement device for diagnosis of peripheral vascular disease in lower extremity using infrared and red LED which produce a peak spectral emission at a wavelength of 660 nm, and 940 nm. To evaluate the clinical application of the oxygen measurement device, we performed lower extremity study to measure the oxygen changes in response to physiological changes within biological tissue. The results showed that oxygen saturation of blood in biological tissue can be monitored from the separation arrangement light source and detector.