• 정보저장시스템학회:학술대회논문집
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• 정보저장시스템학회 2005년도 추계학술대회 논문집
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• pp.59-63
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• 2005

Nowadays, various approaches are performed to increase the storage capacity of optical storage device. One of the promising candidates is using the high NA lens. By using high NA lens, the beam spot size can be reduced which will lead to increase the storage density. This paper proposes a double cantilever beam type bimorph PZT actuator for fine motion that can control the gap between the flexible media and optical pickup which uses high NA lens. Mathematical model is derived by using Hamilton's principle and the model is verified by finite element analysis and experiment. Position controller is designed and its performance is evaluated by experiment.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• 제29권12호
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• pp.8-14
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• 2015

An effective way to ensure that LEDs produce wanted light output is to use a current driving topology, because the brightness of LEDs is directly related to their current. However, this topology may lead to the lifetime shortening of a illumination system because over-currents may flow through non-damaged LEDs in case some LEDs are damaged. This paper presents an adaptive current control circuits for LEDs, which protect LEDs in a good state by limiting the driving currents according to the number of damaged ones. The proposed control circuits consist of a simple constant-current driver and a micro-controller which monitors the voltage of LED array without any auxiliary current sensors for fault diagnosis. And the driving current is automatically controlled into 6-levels according to the number of failures.

• Proceedings of the KIEE Conference
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• 대한전기학회 2001년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.331-333
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• 2001

The flooded type battery is used for solar lighting system. Because the characteristic of flooded type battery is the short life time, the maintenance cost is high. So the using floe fed type battery in this system is inappropriate. The valve regulated lead acid batter(VRLA) is the maintenance free and cycle service purpose. This paper presents the development of control system and monitoring system to applied VRLA battery for maintenance free and long life time in system.

• Proceedings of the KIEE Conference
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.1047-1050
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• 1993

Recently, AC servo motor has expanded its application areas the to the development of the power semi-conductor and control technology. But it has large torque ripple for its nonlinear characteristics and phase commutaion. In this paper, we proposed the switching angle overlapping method, and current control using tracking method in order to generate the constant torque of AC servo motor that has the trapezoidal back e.m.f. It is compared the these types of control method with the characteristics through simulation. We show that these methods lead the torque ripple to reduce and makes the position and speed characterlistics improved effectively. Also we prove that current control using tracking method is the best way to reduce torque ripple among the these types of control method.

• Proceedings of the KIEE Conference
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1102-1103
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• 2007

This Paper presents a solution to control the Brushless DC Motor(BLDCM) in Digital Lightening Processor(DLP) using the Linear Quadratic Regulator(LQR). Generally, The speed of BLDCM in DLP is controlled by the lead angle control or the input voltage control using PAM(Pulse Amplitude Modulation) etc. These control methods have speed overshoot in speed control and need the long time until BLDCM reaches at the steady state. In order to improve the performance, this paper present the PI speed controller using the LQR based on vector control and the rotor position detection methods at the space vector PWM inverter. The proposed methods are proved by the experimental results

• Transactions of the Korean Society for Noise and Vibration Engineering
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• 제17권6호
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• pp.539-546
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• 2007

Information storage devices using disks have a disk vibration at the frequency which is equivalent to the disk rotational speed. They also have a track vibration due to the disk eccentricity at the same frequency. In near field recording systems, the former affects the air-gap servo and the latter affects the tracking servo. In this paper, we introduce a novel control algorithm based on the internal model principle to both servos. A controller block designed by the principle is connected to the base lead-lag type compensator in parallel in order to cancel the repeatable run-out due to the disk vibration or eccentricity. Simulation and practical application of the algorithm on a near field recording system show good servo performance.

• Asia Marketing Journal
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• 제21권4호
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• pp.45-57
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• 2020

With the development of new technologies, virtual reality (VR) is emerging as a new consumer marketing platform. Yet, only a few studies have investigated VR in the consumption context. The current research explores how experiencing a product through VR influences consumer attitude and purchase intention for the product. Although assessing products in real life is believed to be more diagnostic than that through VR, the present research revealed that experiencing a product through VR could lead to a more positive attitude toward and higher purchase intention for the product. We also demonstrated that "enjoyment" has a mediating effect while evaluating the product through VR. To compare product experience through VR to that in real life, we employed the HTC Vive VR system to implement a VR environment. In the VR condition, participants evaluated plastic building blocks using a VR headset and a motion controller; and in the real life (reality) condition, they evaluted plastic building blocks printed using a 3D printer to make them look exactly the same as the blocks used in the VR condition. Finally, implications and suggestions are discussed.

• The Journal of the Korea institute of electronic communication sciences
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• 제11권12호
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• pp.1209-1218
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• 2016

In order to safely and speedily transport a load such as a large glass plate using four electric cylinders, the synchronous error outside the permitted range should not be continuously generated between the cylinders. In this study, a methodology of synchronous control which can be applied to synchronization of four or more cylinders is developed. The synchronous control system based on the decoupling structure is composed of a reference model, position and synchronous controllers in the respective cylinders. The reference model is used for calculating the decoupled synchronous error and control input for the each cylinder. The position controller of I-PD type is designed in order that the cylinder may follow the reference signal without overshoot and input saturation. And the synchronous controller of lead compensator is designed to achieve stable and accurate synchronization through loop shaping approach. Finally, the simulation results show that the synchronization between the four cylinders can be quickly and stably while each cylinder rod is transferred to the target point under torque disturbance.

• The Transactions of the Korea Information Processing Society
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• 제6권1호
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• pp.182-192
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• 1999

The advance of the MPEG(Moving Picture Expert Group) and DSP(Digital Signal Processing) technologies lead the energence of the information appliances which are gradually digitalized and embedded the high-speed networking function. This paper proposes a CHANCE(Cost-effective Home ATM Network for the Consumer Electronics) protocol supporting the ATM-based high-speed networking between the information appliances within the home, and designs its specific functions including the network management and signalling function. The CHANCE protocol is basically based on the tree topology, and supports the plug-and-play function by using only the header field of the ATM cells. Unlike the existing ATM Warren protocol which uses the source routed addressing scheme to control the in-home devices from the Warren controller, the CHANCE protocol can support the inter-device controls as well as the controls from the CHANCE controller by using the switch and device identifier.

• Journal of Korean Association for Spatial Structures
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• 제11권2호
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• pp.89-99
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• 2011

In this study, a smart base isolation system has been proposed to reduce dynamic responses of a spacial structure subjected to seismic excitation. MR dampers and low damping elastomeric bearings were used to compose a smart base isolation system and its vibration control performance has been investigated compared to that of the optimally designed lead-rubber bearing (LRB) isolation system. Control performance of smart base isolation system depends on control algorithm. Fuzzy controller was used in this study to effectively control the spacial structure having a smart base isolation system. Dynamic responses of the spacial structure with isolation system is conflict with base drifts and thus these two responses are selected as objective functions to apply multi-objective genetic algorithm to optimization of fuzzy controller. Based on numerical simulation results, it has been shown that the smart base isolation system proposed in this study can drastically reduce base drifts and seismic responses of the example spacial structure in comparison with the optimally designed LRB isolation system.