• 해양환경안전학회지
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• 제21권6호
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• pp.770-777
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• 2015

본 논문에서는 전동기 구동장치를 선정하여 리액터 용량 및 종류, 부하의 크기에 따라 고조파 왜형률 변화추이를 검토하여 선박 및 해양플랜트에 적용 가능한 최적의 용량선정 근거를 마련하였다. AC라인 리액터와 DC링크 리액터는 가변주파수 구동장치 입력전류의 고조파를 크게 저감시키는 역할을 하며, 동일한 효과를 얻기 위한 DC링크 리액터의 인덕턴스가 AC라인 리액터 인덕턴스의 약 1.7배가 되어야 한다는 것을 시뮬레이션을 통하여 고찰하였다. 소프터웨어 PSIM을 활용하여 각 상황에 따른 전류 고조파 왜형률을 분석하였다.

• 제어로봇시스템학회논문지
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• 제7권8호
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• pp.680-688
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• 2001

In this paper, the fuzzy control with variable input gain is applied to maintain the consistent tension in the process of taking up and releasing texture. In the process of discharging web on one side rolling it on another, the take-up drum gets smaller on the release drum side as it gets bigger on the rolling side, thus it is necessary to change the balance of velocity between the sides. In order to solve the problem a tension controller is necessary. The PI control method has been employed to maintain the consistent tension, but the PI control method produces a problem which requires an experienced worker with the traits of the machine, in order to perform the fine adjustments according to the environment of the process. For solving the above problem, we apply fuzzy control to the tension system, in order to produce a uniform roll. For the performance test, the fuzzy controller does not need to revise the parameters. Therefore the fuzzy controller exhibits an excellent additivity for the tension system where the system is changed with time.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.910-913
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• 2001

Rapid Prototyping(RP) techniques have unique characteristics according to their working principle: the stair-stepped surface of a part due to layer-by-layer stacking, low building speed, and additional post-processing to improve surface roughness. A new RP process, Variable Lamination Manufacturing by using expandable polystyrene foam(VLM-S), has been developed to overcome the unfavorable characteristics. The objective of this study is to investigate the thermal characteristics and skeleton size effects as the hotwire cuts EPS foam sheet in order to improve dimensional accuracy of the parts, which is produced by VLM-S. Empirical and analytical approaches are performed to find the relationship between cutting speed and heat input, and the relationship between maximum available cutting speed and heat input. In addition, empirical approaches are carried out to find the relationship between cutting error and skeleton size, and cutting deviation and skeleton size. Based on these results, the optimal hotwire cutting condition and available minimum skeleton size are derived. The outcomes of this study are reflecting in the enhancement of VLM-S input data generation S/W.

• Journal of Power Electronics
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• 제10권2호
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• pp.115-124
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• 2010

In this paper, a simple yet efficient auto mode-hop ripple control structure for buck converters with light load operation enhancement is proposed. The converter, which operates under a wide range of input and output voltages, makes use of a state-dependent hysteretic comparator. Depending on the output current, the converter automatically changes the operating mode. This improves the efficiency and reduces the output voltage ripple for a wide range of output currents for given input and output voltages. The sensitivity of the output voltage to the circuit elements is less than 14%, which is seven times lower than that for conventional converters. To assess the efficiency of the proposed converter, it is designed and implemented with commercially available components. The converter provides an output voltage in the range of 0.9V to 31V for load currents of up to 3A when the input voltage is in the range of 5V to 32V. Analytical design expressions which model the operation of the converter are also presented. This circuit can be implemented easily in a single chip with an external inductor and capacitor for both fixed and variable output voltage applications.

• 전력전자학회논문지
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• 제22권6호
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• pp.517-526
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• 2017

In this paper, we propose an LLC resonant converter that operates over a wide controllable output voltage ($50V_{DC}$ to $800V_{DC}$) and shows high efficiency characteristics under all load conditions and output voltages. Two 3.3kW prototypes are designed for an experimental comparison between the variable frequency control (control scheme 1) and the variable input voltage($V_{IN}$) control (control scheme 2) mechanisms. The experimental results show that the variable input control mechanism demonstrates high efficiency under all loads and output voltages.

• 대한전자공학회논문지
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• 제25권5호
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• pp.528-535
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• 1988

This paper presents a constructing theory of variable arithmetic operation systems for computing multiplications and multiplicative inverse in GF(2**m) based on a modulo operation of degree on elements in Galois fields. The proposed multiplier is composed of a zero element control part, input element conversion part, inversion circuit, and output element conversion part. These systems can reduce reasonable circuit areas due to the common use of input/output element converison parts, and the PLA and module structure provice a variable property capable of convertible uses as arithmetic operation systems over different finite fields. This type of designs gives simple, regular, expandable, and concurrent properties suitable for VLSI implementation. Expecially, the multiplicative inverse circuit proposed here is expected to offer a characteristics of the high operation speed than conventional method.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.759-762
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• 2002

In this paper, a voltage-controlled linear variable resistor (VCLVR) using a floating-gate MOS-FET (FG-MOSFET) is proposed. The proposed-circuit is the grounded VCLVR consists of only an ordinary MOSFET and an FG-MOSFET. The advantage of the proposed VCLVR are low-voltage and wide-input range. Next, as applications, a floating-node voltage controlled variable resistor and an operational transconductance amplifier using the proposed VCLVRs are proposed. The performance of the proposed circuits are characterized through HSPICE simulations with a standard 0.6 ${\mu}$m CMOS process. simulations of the proposed VCLVR demonstrate a resistance value of 40 k$\Omega$ to 338 k$\Omega$ and a THD of less than 1.1 %.

• 전자공학회논문지B
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• 제32B권12호
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• pp.1670-1679
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• 1995

In this paper, an optimal variable structure controller with a multilayer neural inverse identifier is proposed. A multilayer neural network with error back propagation learning algorithm is used for construction the neural inverse identifier which is an observer of the external disturbances and the parameter variations of the system. The variable structure controller with the multilayer neural inverse identifier not only needs a small part of a priori knowledge of the bounds of external disturbances and parameter variations but also alleviates the chattering magnitude of the control input. Also, an optimal sliding line is designed by the optimal linear regulator technique and an integrator is introduced for solving the reaching phase problem. Computer simulation results show that the proposed approach gives the effective control results by reducing the chattering magnitude of control input.

• 전기전자학회논문지
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• 제18권2호
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• pp.206-213
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• 2014

In this note, a new robust nonlinear output feedback variable structure controller is first systematically and generally designed for the output control of more affine uncertain nonlinear systems with mismatched uncertainties and matched disturbance. A transformed integral output feedback sliding surface with a most simple form is applied in order to remove the reaching phase problems. The closed loop exponential stability and the existence condition of the sliding mode on the integral output feedback sliding surface is investigated with a corresponding output feedback control input in Theorem 1. For practical application the continuous implementation of the control input is made by the modified saturation function. The effectiveness of the proposed controller is verified through a design example and simulation study.

• 한국컴퓨터정보학회논문지
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• 제23권4호
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• pp.65-70
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• 2018

This paper describes a effective information compressor algorithm for the fourth industrial technology. One of the difficult problems for outdoor is to obtain effective updating process of background images. Because input images generally contain the shadows of buildings, trees, moving clouds and other objects, they are changed by lapse of time and variation of illumination. They provide the lowering of performance for surveillance system under outdoor. In this paper, a effective information algorithm for variable environment variable under outdoor is proposed, which apply the Kalman Estimation Modeling and adaptive threshold on pixel level to separate foreground and background images from current input image. In results, the better SNR of about 3dB~5dB and about 10%~25% noise distribution rate in the proposed method. Furthermore, it was showed that the moving objects can be detected on various shadows under outdoor and better result Information.