• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.407-408
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• 2017

In regenerative mode of an IPMSM control system without a bi-directional DC-DC converter, the 3-phase PWM inverter charges the battery. At this time, the regenerative torque reference for braking must output the proper torque reference to charge the battery. This paper proposed a regeneration control method that controls the voltage and current of the battery through CC-CV control at the regenerative braking torque corresponding to the driver's brake control.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.8
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• pp.1-10
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• 2008

In this paper, we describe a design of a 128bit MRAM based on a new switching architecture which is Local Field Switching(LFS). LFS uses a local magnetic field generated by the current flowing through an MTJ. This mode reduces the writing current since small current can induce large magnetic field because of close distance between MTJ and the current. It also improves the cell selectivity over using conventional MTJ architecture because it doesn't need a digit line for writing. The MRAM has 1-Transistor 1-Magnetic Tunnel Junction (IT-1MTJ) memory cell structure and uses a bidirectional write driver, a mid-point reference cell block and a current mode sense amplifier. CMOS emulation cell is adopted as an LFS-MTJ cell to verify the operation of the circuit without the MTJ process. The memory circuit is fabricated using a $0.18{\mu}m$ CMOS technology with six layers o) metal and tested on custom board.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.06a
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• pp.293-298
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• 2013

This research develops an ultrasonic sensor to measure the distance in underwater. The ultrasonic transducer transmits an acoustic signal to an object and receives the echo signal reflected from the object. The ultrasonic driver calculates a distance by multiplying the acoustic speed to the time of flight(TOF) which is the time necessary for the acoustic signal to travel from the transducer to the object. We apply a thresholding and a cross correlation methods to detect the TOF and show their results. When an echo pulse is corrupted with noise and its shape is distorted, the cross correlation method is used to find the TOF based on the maximum similarity between the reference and the delayed echo signals. The echoes used for the reference signal are achieved at the different environments, which improves the performance of the sensor. This paper describes the driver of the acoustic sensor and analyzes the performance of sensors in different measurement environments.

• Journal of Energy Engineering
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• v.25 no.1
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• pp.163-170
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• 2016

In the condition of electronic controlled acceleration system, APS Sensor is the only and the most important parts to reflect the will of driver. Especially, the non-reference type APS is the critical part of this system. It can't provide the cross-reference values and it will make the vehicle goes into the 'NMC(Non-moveable condition)' or 'Limp-home mode' on the malfunction situation easier. If the situation is happened, it's very dangerous condition for the drivers, soldiers and war material systems of battlefield. The electronic control is not a necessary system for the tactical vehicles. The tactical vehicles must be prepared the manual control system independently from the electronic control system to escape, save and rescue the soldier's life and war materials. Therefore it was studied the water-penetrated broken APS output. If the output value was changed without driver's will, even the cross-reference type APS, it will effect the uncontrollable engine RPM changing or the performance down on limp-home mode. It means the manual control system of tactical vehicle is needed for any kinds of APS.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.1
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• pp.98-106
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• 2009

This work proposes a 1280-RGB $\times$ 800-Dot 70.78mW 0.l3um CMOS LCD driver IC (LDI) for high-performance 16M-color low temperature poly silicon (LTPS) thin film transistor liquid crystal display (TFT-LCD) systems such as ultra mobile PC (UMPC) and mobile applications simultaneously requiring high resolution, low power, and small size at high speed. The proposed LDI optimizes power consumption and chip area at high resolution based on a resistor-string based architecture. The single column driver employing a 1:12 MUX architecture drives 12 channels simultaneously to minimize chip area. The implemented class-AB amplifier achieves a rail-to-rail operation with high gain and low power while minimizing the effect of offset and output deviations for high definition. The supply- and temperature-insensitive current reference is implemented on chip with a small number of MOS transistors. A slew enhancement technique applicable to next-generation source drivers, not implemented on this prototype chip, is proposed to reduce power consumption further. The prototype LDI implemented in a 0.13um CMOS technology demonstrates a measured settling time of source driver amplifiers within 1.016us and 1.072us during high-to-low and low-to-high transitions, respectively. The output voltage of source drivers shows a maximum deviation of 11mV. The LDI with an active die area of $12,203um{\times}1500um$ consumes 70.78mW at 1.5V/5.5V.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.541-543
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• 1998

Generally, PI control is simple and easy to implement and gains of PI control are determined by specifying a dynamics of the servo driver system. However, the gain-tuning is so difficult that it is relied on an expert's effort. This paper presents a gain auto-tuning method for PI controllers based on a fuzzy inference mechanism. First, the proposed fuzzy inference system identifies a system moment of inertia and adjusts control gains by using the difference in speed responses between a real plant and a reference model. Second, this paper proposes an improved fuzzy PI controller. To reduce the speed overshoot, we adapt a control method that selects a proper PI gains with respect to the load inertia variation. To prove the validity of the proposed gain tuning algorithm and the feasibility of the servo drive, a high performance servo drive will be implemented by DSP(TMS320C31) and intelligent power module (IPM). The proposed controller is applied to the speed control of the 300W AC servo motor. Some simulations and experimental results show that the proposed fuzzy PI controller is more robust than the conventional PI controller against the load inertia variation.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.7
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• pp.632-638
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• 2010

This paper presents an optimum tire force distribution method for 6WD/6WS(6-Wheel-Drive and 6-Wheel-Steering) electric vehicles. Using an independent steering and driving system, the performance of 6WD/6WS vehicles can be improved, as, for example, with respect to their maneuverability under low speed and their stability at high speed. Therefore, there should be a control strategy for finding the optimum tire forces that satisfy the driver's command and minimize energy consumption. From the driver's commands (steering angle and accelerator/brake pedal stroke), the desired yaw moment, the desired lateral force, and the desired longitudinal force were obtained. These three values were distributed to each wheel as the torque and the steering angle, based on the optimum tire force distribution method. The optimum tire force distribution method finds the longitudinal/lateral tire forces of each wheel that minimize the cost function, which is the sum of the normalized tire forces. Next, the longitudinal/lateral tire forces of each wheel are converted into the reference torque inputs and the steering wheel angle inputs. The proposed method was tested through a simulation, and its effectiveness was verified.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.3
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• pp.437-443
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• 1987

An optimal design to improve the ride quality was performed with the time and frequency domain analysis based on both of deterministic and random road profiles. The objective function is established to minimize the absorbed power while the constraints are taken so as to satisfy the condition for the stability of vehicle. The result of the optimal design shows that the rms for the acceleration of a driver and his seat is within the critical values for the ride quality from ISO. The optimal values obtained show that the maximum absolute acceleration of the driver and his seat has significantly been reduced and the reference limits on the relative displacement have satisfied their feasibility. As the optimal value according to a specific speed is the results from the optimization process, a global optimum value should be determined to be the one which gives th minimum values of total sum of absorbed power with respect to various speed.

• Journal of Sensor Science and Technology
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• v.25 no.1
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• pp.13-19
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• 2016

Nowadays, most major automobile manufacturers are very interested, and actively involved, in developing driver alcohol detection system for safety (DADSS) that serves to prevent driving under the influence. DADSS measures the blood alcohol concentration (BAC) from the driver's breath and limits the ignition of the engine of the vehicle if the BAC exceeds the reference value. In this study, to optimize the sensor array of the DADSS, we selected sensors by using three different methods, configured the sensor arrays, and then compared their performance. The Wilks' lambda, stepwise elimination and filter method (using a principal component) were used as the sensor selection methods [2,3]. We compared the performance of the arrays, by using the selectivity and sensitivity as criteria, and Sammon mapping for the analysis of the cluster type of each gas. The sensor array configured by using the stepwise elimination method exhibited the highest sensitivity and selectivity and yielded the best visual result after Sammon mapping.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.11-13
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• 2019

This paper proposes a novel high step-up non-isolated DC-DC converter, suitable for regulating dc bus in various inherent low voltage micro sources especially for photovoltaic (PV) and fuel cell sources. This novel high voltage Non-isolated Boost DC-DC converter topology is best replacement, where high voltage conversion ratio is required without the transformer and also need continuous input current. Since the proposed topology utilizes the stack-based structure, the voltage gain, and the efficiency are higher than other conventional non-isolated converters. Switches in this topology is easier to control since its control signal is grounding reference. Also, there is no need of extra gate driver and extra power supply for driver circuit, which reduces the cost and size of system. In order to show the feasibility and practicality of the proposed topology principle operation, steady state analysis and simulation result is presented and analyzed in detail. To verify the performance of proposed converter and theoretical analysis 360W laboratory prototype is implemented.