• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.2
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• pp.165-170
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• 2002

In order to solve the problem of system efficiency reduced on account of two stage power conversion, we propose a series resonant full bridge Inverter circuit for battery-fed microwave oven. This circuit has both a compact size and a light weight comparing with the conventional HVT(High Voltage Transformer) method. Also, it may be adjusted power levels of the microwave oven by a frequency control. In this paper, operational principles are explained in detail in order to understand the circuit operation. Also, a proto-type Inverter circuit with 1[kW] Power consumption is built and tested for verifying the operation.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.112-114
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• 2005

In today's hyper-competitive business environment, Radio Frequency Identification (RFID) technology is expected to enhance the operation efficiency of supplying chain management in both manufactures and retail industries. However, the widespread deployment of RFID tags may create new threats to user privacy, due to the powerful tracking capability of the tags. Many authentication protocols for RFID have been proposed. They are helpful preventing passersby being scanned to determine what articles they are carrying. However, most of them would not prevent the bigger physical tracking problem of RFID, especially when being tracked by the 'constellation' of products they carry. We proposed this RFID scheme to prevent these tracking problems.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.11 no.2
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• pp.34-38
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• 2012

In this paper, the particle swarm optimization (PSO) algorithm is adopted to design a modified ring-slot type patch rectenna with a resonance frequency of 2.45GHz. In order to accomplish minimization of dimensions and circular polarization (CP) and harmonic suppression, axial direction slits and side-cuts are added to the patch of the ring. The PSO manipulated this kind of multi-dimensional problem very well, and as a result, the designed rectenna shows a desirable performance of return loss of 21.36dB and axial ratio of 2.92dB at the frequency of 2.45GHz with compact sizing.

• Structural Engineering and Mechanics
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• v.33 no.1
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• pp.47-66
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• 2009

Radiation damping due to wave propagation in unbounded domains may cause a significant reduction of structural vibrations when excited near resonance. Here a novel matrix-valued algebraic Pad$\acute{e}$-like stiffness formulation in the frequency-domain and a corresponding state equation in the time domain are elaborated for a soil-structure interaction problem with a layered soil excited in a transient manner by a flexible rotor during startup and shutdown. The contribution of radiation damping caused by a soil-layer upon a rigid bedrock is characterized by the corresponding amount of critical damping as it is used in structural dynamics.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.12
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• pp.1091-1097
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• 2011

In the present study, TMD(tuned mass damper) with eddy current damping is proposed to suppress the vibration of a cantilever beam effectively. The advantages of TMD are that it is simple and its performance are excellent at any particular frequency. However, TMD may have the low performance at other frequency. To solve this problem and improve its performance, this study applies the eddy current damping to TMD. This TMD with ECD is named as MTMD(magnetically tuned mass damper). MTMD is designed for the vibration suppression of a cantilever beam. The mathematical modeling, simulation, and experiments of the cantilever beam with MTMD are performed. From analytic and experimental results, it can be concluded that the vibration suppression performance of MTMD are excellent.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.1
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• pp.39-46
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• 1999

Disturbances acting on the track-following servo system of an optical disk drive inherently contain significant periodic components that cause tracking errors of a periodic nature. Such disturbances can be effectively rejected by employing a repetitive controller, which must be implemented carefully in consideration of system stability. Plant uncertainty makes it difficult to design a repetitive controller that will improve tracking performance yet preserve system stability. In this paper, we examine the problem of designing a repetitive controller for an optical disk drive track-following servo system with uncertain plant coefficients. We propose a graphical design technique based on the frequency domain analysis of linear interval systems. This design method results in a repetitive controller that will maintain system stability against all admissible plant uncertainties. We show simulation and experimental results to verify the validity of the proposed design method.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.13-18
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• 2003

This paper proposes a design method of PID controllers in the framework of a constrained optimization problem. Owing to the popularity for the controller's simplicity and robustness, a great deal of literature concerning PID control design has been published, which can be classified into frequency-based and time-based approaches. However, both approaches have to be considered together for a designed PID control to work well with a guaranteed closed-loop stability. For this purpose, a penalty function is formulated to satisfy both frequency- and time-domain specifications, and is minimized by a recet nonlinear optimization algorithm to attain optimal PID control gains. The proposed method is compared with Wang's and Ho's methods on a suite of example systems. Simulation results show that the PID control tuned by the proposed method improves time-domain performance without deteriorating closed-loop stability.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.335-342
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• 2005

Using higher order Mindlin plates and piezoelectric materials, eigenvalue problems are considered. Since piezoelectric crystal resonators produce a proper amount of electric signal for a thickness-shear frequency, the objective is to decouple the thickness-shear mode from the others. Design variables are the bulk material densities corresponding to the mass of masking plates for electrodes. The design sensitivity expressions for the thickness-shear frequency and mode shape vector are derived using direct differentiation method(DDM). Using the developed design sensitivity analysis (DSA) method, we formulate a topology optimization problem whose objective function is to maximize the thickness-shear component of strain energy density at the thickness-shear mode. Constraints are the allowable volume and area of masking plate. Numerical examples show that the optimal design yields an improved mode shape and thickness-shear energy.

• Proceedings of the IEEK Conference
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• 2000.11d
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• pp.123-126
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• 2000

In this paper, the portable game machine called W"alking Beat" is designed and implemented not only to propose the new possibilities for the peripheral equipment market of portable acoustic machine but also to overcome the limitation of the acoustic simulation game machine such as the existing Beat Mania. The old game machine can be used only in a particular place, where it is installed. However, in order to get over the constraint on this space problem "Walking Beat Game Machine" is designed to facilitate the portability. In addition, the frequency analysis method using FFT algorithm is employed by regarding the music data for the portable digital acoustic machine as source so that the limitation that the existing game machine depends heavily on the previously registered game contents can be overcome. By making it possible to play games for all the music and putting an emphasis on multimedia trend only to listen to the music, it is speculated that it can contribute to the development of the new culture in the near future.

• Journal of IKEEE
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• v.13 no.2
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• pp.248-252
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• 2009

In this paper, analysis of a noise factor and an effective power strategy for the OLED dc-dc converter are described. One of the main reasons that one may not design the OLED power for dc-dc converter is that OLED's panel noise is composed of FFN(Frame Frequency Noise) and LFN(Line Frequency Noise). Into the bargain, FFN is caused by both the dc-dc (circuit) and driving circuit. It is hard to get rid of FFN, baeause FFN has very little results value for our ears. LFN is adjusted by analog compensation value. Actually, that is more important problem than FFN. It is known that voltage divider for OLED's mode variation is not good for compact power design. In the end, a circuit design for understanding OLED's noise and a novel muti-channel dc-dc converter were presented.