• Structural Engineering and Mechanics
• /
• v.11 no.4
• /
• pp.341-356
• /
• 2001

A new class of semi-active tuned mass dampers, named as "Ground Hook Tuned Mass Damper" (GHTMD) is introduced. This TMD uses a continuously variable semi-active damper (so called 'Ground-Hook') in order to achieve more reduction in the vibration level. The ground-hook dampers have been used in the auto-industry as a means of reducing the vibration of primary suspension systems in vehicles. This paper investigates the application of this damper as an element of a tuned damper for the vibration reduction of force-excited single degree of freedom (SDOF) models that can be representative of many structural systems. The optimum design parameters of GHTMDs are obtained based on the minimization of the steady-state displacement response of the main mass. The optimum design parameters which are evaluated in terms of non-dimensional values of the GHTMD are obtained for different mass ratios and main mass damping ratios. Using the frequency responses of the resulting systems, performance of the GHTMD is compared to that of equivalent passive TMD, and it is found that GHTMDs are more efficient. A design methodology to obtain the tuning parameters of GHTMD using the relationships developed in this paper is presented.

• Annual Conference on Human and Language Technology
• /
• 2011.10a
• /
• pp.147-150
• /
• 2011

본 논문에서는 병렬 말뭉치에서 오류가 있을 것으로 추정되는 문장을 자동 추출하여, 다수의 번역 사전 구축 작업자가 자동 번역시스템을 직접 사용하면서 번역 사전을 튜닝하는 방법에 대하여 제안하고자 한다. 작업자는 병렬 말뭉치의 대역문을 이용하여 자동 번역 결과의 BLEU를 측정하고, 사전 수정 전과 후의 BLEU 차이를 정량적으로 제시해 줌으로써 양질의 번역 사전을 구축하도록 하였다. 대량의 번역 사전이 이미 구축된 자동 번역시스템에서 추가적인 성능향상을 위해 대량의 말뭉치에서 미등록어, 번역패턴 등을 추출하여, 대량으로 구축하는 기존 방법에 비해 사전 구축 부작용이 적으며, 자동번역 성능향상에 더 기여하는 것을 실험을 통해 증명하였다. 이를 위해 본 논문에서는 중한 자동 번역시스템을 대상으로, 중국어 문장 2,193문장에 대해, 사전 구축 작업자 2명이 2주간 튜닝한 결과와 15만 말뭉치에서 추출한 미등록어 후보 2만 엔트리를 3명의 사전 구축 작업자가 미등록어 선별, 품사 및 대역어 부착한 결과 7,200 엔트리를 대상으로 자동평가를 실시하였다. 실험결과 미등록어 추가에 의한 BLEU 성능향상은 +3인데 반해, 약 2,000문장 튜닝 후 BLEU를 +12 향상시켰다.

• Journal of Power Electronics
• /
• v.5 no.3
• /
• pp.198-205
• /
• 2005

The mechanical system of a drive can often be modeled as a two- or three-mass-system. The load is coupled to the driving motor by a shaft able to perform torsion oscillations. For the automatic tuning of the control, it is necessary to know the mathematical description of the system and the corresponding parameters. As the manpower and setup-time necessary during the commissioning of electrical drives are major cost factors, the development of self-operating identification strategies is a task worth pursuing. This paper presents an identification method which can be utilized for the assisted commissioning of electrical drives. The shaft assembly can be approximated as a two-mass non-rigid mechanical system with four parameters that have to be identified. The mathematical background for an identification procedure is developed and some important implementation issues are addressed. In order to avoid the excitation of the system with its natural resonance frequency, the frequency response can be obtained by exciting the system with a Pseudo Random Binary Signal (PRBS) and using the cross correlation function (CCF) and the auto correlation function (ACF). The reference torque is used as stimulation and the response is the mechanical speed. To determine the parameters, especially in advanced control schemes, a numerical algorithm with excellent convergence characteristics has also been used that can be implemented together with the proposed measurement procedure in order to assist the drive commissioning or to achieve an automatic setting of the control parameters. Simulations and experiments validate the efficiency and reliability of the identification procedure.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.7 no.1
• /
• pp.48-54
• /
• 2002

This paper is described the indirect induction heated boiler and induction heated hot air producer using the voltage-fed series resonant high-frequency inverter which can operate in the frequency range from 20 kHz to 50 kHz. A specially designed induction heater is composed of laminated stainless plates, which have many tiny holes and are interconnected by spot welding. This heater is inserted into the ceramic type vessel with external working coil. This working coil is connected to the inverter and turbulence fluid through this induction heater to moving fluid generates in the vessel. The operating performances of this unique appliance in next generation and its effectiveness are evaluated and discussed from a practical point of view.

• Proceedings of the KIEE Conference
• /
• 2002.06a
• /
• pp.25-28
• /
• 2002

본 논문은 마이크로 프로세스로 처리되는 여러 제어장치들 중에서 PI제어기의 최적 자동동조에 관한 개선된 방법을 제안하고자 한다. 이 방법은 Relay 자동동조 법으로서 이를 마이크로 프로세스에 응용하여 제어대상에 최적의 PI계수를 입력하게된다. 이를 위해 먼저 Computer와 DSP사이에 통신이 가능하도록 RS-232를 설치하고, 컴퓨터의 제어신호에 따라 모터의 속도가 Relay와 PI제어기에 의해 목표값에 도달할 수 있도록 설계하였다. 내부적으로 사용된 Relay 동조방식은 Relay로 제어대상의 출력을 강제로 진등시켜서 출력의 진폭과 주기를 이용하여 PI 계수를 조정하고 제어기의 입력값으로 선택된다. Relay동조 법은 동조과정이 간단하여 동조 방식의 구현이 쉽다. 또 위상여유를 고려하여 제어기의 계수를 조정하기 때문에 시스템의 견실성을 향상시킬 수 있을 뿐 아니라, 비례 제어만으로 임계 진동을 하지 않는 시스템의 경우에도 사용할 수 있고, 원점에 극점이 있는 경우에도 적용할 수 있어서 기존의 제어방식이 가지는 제약성의 한계를 극복할 수 있어서 적용성이 우수하다.

• Proceedings of the KIEE Conference
• /
• 1996.07b
• /
• pp.1377-1379
• /
• 1996

In this paper, each parameter was identified by the gradient descent method to overcome difficulty deciding fuzzy rules of FLC for the unknown process and the type of membership Junctions. Usually PID or optimal control theories have been mostly usee in control field so far. However, optimal control requires much time for calculation because of adaptation for disturbance and nonlinearity. And intricate technique such as MRAS which can be realized only by an expert are limited to be used in the systems requiring rapid and precise response because of comparatively longer calculating time and complicateness. Gradient descent method is a method to find Z minimizing a function about a certain vector Z. And required output of FLC is gained using gradient approaching method in order to adapt control rule parameters of FLC. Simulation proved validation of this algorithm.

• Proceedings of the KIPE Conference
• /
• 2012.07a
• /
• pp.359-360
• /
• 2012

This paper proposes a scheme of auto-tuning fuzzy PI controller and input voltage feed forward to control the output voltage of a three-phase Z-source inverter (ZSI). The proposed scheme adjusts the ts (Kp and Ki) in real time in order to find the most suitable Kp and Ki for PI controller and to simplify the controller design. The proposed scheme is verified the validity by experiment and co-simulation in PSIM and MATLAB/SIMULINK both load step change and input DC voltage variation in Z-source inverter, and has compared with the conventional PID control scheme. The experiment results involve of three-phase output voltage, Z-network capacitor voltage and dc-link peak voltage value. By those analysis and comparison, the availability of the proposed method in output voltage transient response quality improving has been verified. Compared with conventional PID method, the proposed method showed a more effective and robust control performance for coping with the severe disturbance conditions.

• Journal of Internet Computing and Services
• /
• v.22 no.3
• /
• pp.9-16
• /
• 2021

This study aims to develop a human activity recognition (HAR) system as a Deep-Learning (DL) classification model, distinguishing various human activities. We solely rely on the signals from a wristband accelerometer worn by a person for the user's convenience. 3-axis sequential acceleration signal data are gathered within a predefined time-window-slice, and they are used as input to the classification system. We are particularly interested in developing a Deep-Learning model that can outperform conventional machine learning classification performance. A total of 13 activities based on the laboratory experiments' data are used for the initial performance comparison. We have improved classification performance using the Convolutional Neural Network (CNN) combined with an auto-encoder feature reduction and parameter tuning. With various publically available HAR datasets, we could also achieve significant improvement in HAR classification. Our CNN model is also compared against Recurrent-Neural-Network(RNN) with Long Short-Term Memory(LSTM) to demonstrate its superiority. Noticeably, our model could distinguish both general activities and near-identical activities such as sitting down on the chair and floor, with almost perfect classification accuracy.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.11
• /
• pp.94-100
• /
• 2014

In this paper, a design of low power Current-Reuse Voltage Controlled Oscillator (VCO) which has wide tuning range about 1.95 GHz ~ 3.15 GHz is presented. Class-C type is applied to improve phase noise and 2-Step Auto Amplitude Calibration (AAC) is used for minimizing the imbalance of differential VCO output voltage which is main issue of Current-Reuse VCO. The mismatch of differential VCO output voltage is presented about 1.5mV ~ 4.5mV. This mismatch is within 0.6 % compared with VCO output voltage. Proposed Current-Reuse VCO is designed using CMOS $0.13{\mu}m$ process. Supply voltage is 1.2 V and current consumption is 2.6 mA at center frequency. The phase noise is -116.267 dBc/Hz at 2.3GHz VCO frequency at 1MHz offset. The layout size is $720{\times}580{\mu}m^2$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.24 no.3
• /
• pp.219-232
• /
• 2013

This paper presents a microstrip antenna which recovers its resonant frequency and impedance shifted automatically by the approach of other objects such as hands. This can be used for telemetry sensor applications in the ultrahigh frequency(UHF) industrial, scientific, and medical(ISM) band. It is the key element that an frequency-reconfigurable antenna could be electrically controlled. This antenna is miniaturized by loading the folded plates at both radiating edges, and varactor diodes are installed between the radiating edges and the ground plane to control the resonant frequency by adjusting the DC bias asymmetrically. Using this voltage-controlled antenna and the micro controller peripheral circuits of reading the returned level, the antenna is designed and fabricated which recovers its resonant frequency and impedance automatically. Designed frequency auto recovering antenna is conformed to be recovered within a few seconds when the resonant frequency and impedance are shifted by the approach of other objects such as hand, metal plate, dielectric and so on.