• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.152-155
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• 2014

This paper describes a design of digital PWM controller for automotive brake solenoid valve which is used in ABS/ESC SoC. The PWM controller which consists of 12 channels supports both direct control and PI control. Six channels in direct control mode make consistent PWM signals according to duty ratio setting, and the others in PI control mode make PWM signals with constant current depending on current setting. The PWM controller also has functions including solenoid valve open detection, Dither and PWM phase shift. The PWM controller having 44,779 gates is fabricated using a 0.18um CMOS process, and test results show that all the functions are correct.

• Journal of Information Display
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• v.10 no.4
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• pp.184-187
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• 2009

A liquid crystal device with switchable dynamic and memory modes was investigated and developed. The proposed device reveals the splay, $\pi$-twist, and bend states via selective switching among them. In the dynamic mode, the device is operated in the bend state, which exhibits a wide viewing-angle and a fast-response-time due to its self-compensated bend structure and flow-accelerated fast response time, respectively. In the memory mode, the permanent memory characteristics in the splay and $\pi$-twist sates are obtained, respectively. The switching mechanisms of the tristate device are also proposed.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.954-958
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• 2004

본 논문은 부하에 대한 빠른 응답특성을 보이는 새로운 토폴로지를 제안하였다. PI제어기 출력이 포화될 때 windup 현상이 나타나고 그 결과로 성능이 저하된다. 따라서 전동기의 가변속 제어성능을 위해 가속시에는 개선된 Anti-windup PI제어기만을 사용하고, 감속시에는 추가로 부하의 특성을 고려하여 braking 동작을 사용하였다. 시뮬레이션 및 실험결과는 속도성능면에서 제안된 방식이 종래의 다른 제어방식에 비해 우수함을 보여 준다.

• Journal of Magnetics
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• v.12 no.1
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• pp.27-30
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• 2007

Experimental evidence suggests that spin pinning conditions for standing spin mode in polycrystalline $Ni_{84}Fe_{16}$ alloy film, is confirmed using the four categories of Camley et al. and the value of q$\bot$ for the pinning conditions, this was achieved by performing Brillouin light scattering measurements. The value of q$\bot$ was observed, in order to increase at a rate of $\pi$/2 with an increasing mode number. With this condition, the coexistence of standing spin wave modes was shown, with intermediate pinning, in addition to free and strong pinning. The values for spin-wave-stiffness constant ($D_B$), g-factor (g), and surface magnetization (4$\pi$M) of the Permalloy film were obtained from the results of BLS, and determined to be $D_B=1.85{\pm}0.05Oecm^2$, $g=2.11{\pm}0.02$, and 4$\pi$M=8.7 kG, respectively.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2001.06a
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• pp.105-108
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• 2001

In this paper, we proposed a variable structure controller with fuzzy PI-쇼pe reaching law. we fuzzified as inputs to fuzzy system Rf(representative point's orthogonal distance(rd) to switching surface and RP's distance(r) to the origin of the 2-dimensional space whose coordinates are the error and the error rate. The increments of the coefficients $k_{p}$ and $k_{i}$, of the reaching law are calculated appropriate by the simplified Mamdanl inference. The proposed fuzzy PI-type reaching law makes it reduce the chattering and has no need to tune the PI parameters of reaching law. The effectiveness of the proposed fuzzy PI-type reaching law is shown by the simulation results of the control of a Ball-balance System.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.67-68
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• 2015

본 논문은 폐루프 고피나스 자속관측기의 P/PI모드를 전환하여 전환점부근 저속에서 모터상수 변동에도 강인한 센서리스 벡터제어가 가능한 전환기법을 제안하였다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.05a
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• pp.51-54
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• 2000

In variable structure control algorithm, sliding mode makes the closed loop system insensitive to modelling uncertainties and external disturbances. However due to imperfections in switching, the system trajectory chatters, which is very undesirable. And the insensitivity property of a sliding mode controller is present only when the system is in the sliding mode. To overcome these shortcomings, in this paper, new sliding mode control algorithm using time-varying sliding surface and fuzzy PI structrue is proposed.

• Nuclear Engineering and Technology
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• v.31 no.2
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• pp.202-213
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• 1999

Effects of the rotary inertia of concentrated masses on the natural vibrations of fluid conveying pipes have been studied by theoretical modeling and computer simulation. For analysis, two boundary conditions for pipe ends, simply supported and clamped-clamped, are assumed and Galerkin's method is used for transformation of the governing equation to the eigenvalues problem and the natural frequencies and mode shapes for the system have been calculated by using the newly developed computer code. Moreover, the critical velocities related to a system instability have been investigated. The main conclusions for the present study are (1) Rotary inertia gives much change on the higher natural frequencies and mode shapes and its effect is visible when it has small value, (2) The number and location of nodes can be changed by rotary inertia, (3) By introducing rotary inertia, the second natural frequency approaches to the first as the location of the concentrated mass approaches to the midspan of the pipe, and (4) The critical fluid velocities to initiate the system unstable are unchanged by introduction of rotary inertia and the first three velocities are $\pi$, 2$\pi$, and 3$\pi$ for the simply supported pipe and 2$\pi$, 8.99, and 12.57 for the clamped-clamped pipe.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.11
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• pp.538-543
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• 2006

A high-Power continuous-wave (CW) ten-vane double-strapped magnetron oscillator has been investigated using three-dimensional (3D) particle-in-cell (PIC) numerical simulation code, MAGIC3D. The resonant modes and their resonant frequencies of the ten-vane strapped magnetron resonator were obtained to show a large mode separation near the ${\pi}$-mode. An electron cloud formed in an anode-cathode gap, called an interaction space was confined well enough to result in no leakage current. Five spokes were clearly observed in the electron cloud, which definitely ensured the ${\pi}$-mode oscillation in the ten-vane magnetron. Numerical simulations predicted that the saturated microwave output power measured at the coaxial output port was 5.41 kW at the microwave frequency of 893 MHz, corresponding to a power conversion efficiency of 72.6% when the external axial magnetic field was 1150 gauss and the electron beam voltage and current were 6 kV and 1.25 A, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.5143-5149
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• 2011

In this paper, using the adaptive sliding mode observer for speed sensorless vector control is proposed. Adaptive sliding mode observer of the motor stator coordinate system using the voltage equations of the rotor flux components are observed. Motor speed was obtained by the Lyapunov function is estimated by the relationship further. In order to establish such a control scheme based on the way conventional PI controller and sliding mode observer annexing characteristics of the system through simulation and experiment were compared. According to analysis by comparison with the usefulness of the system was confirmed.