• 한국군사과학기술학회지
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• 제16권1호
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• pp.89-94
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• 2013

Electro Otical Tracking System(EOTS) is required for a rapid movement as well as the stabilization of Line-Of-Sight(LOS). In order to achieve these two goals, this paper presents a position and velocity driving profile generation method from the constant acceleration and deceleration profile according to the current state, enabling a fast and smooth trajectory even if the target position changes during the movement of LOS. Simulation and experimental results reveal that the settling time could be reduced significantly by adopting the present position control scheme.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.1228-1230
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• 1998

The deadbeat control has many advantage such as the ouput response without a ripple and the fast settling time. This paper presents a deadbeat control system to damp out the sustained low frequency oscillation. The proposed deadbeat control system consists of th integral controller and the state observer, and it is simulated on the one-machine infinite-bus model of a power system. The efficiency of the proposed control system is verified through the several case studies.

• Journal of Power Electronics
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• 제2권2호
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• pp.130-138
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• 2002

The windup phenomenon appears and degrades control performance when a controller with integrating action is used and plant input is limited. An anti-windup integal-proportional(IP) controller is proposed for the variable-speed moter drives and it is experimentally applied to the speed control of a vector-controlled induction moter driven by a pulse width modulated (PWM) voltage source inverter (VSI). The consistency range of the IP controller is firstly derived and the intergal state is controlled to salisfy always the consistency range according to whether the the controller output is saturated or not. Although the operating condition like moter load or speed command is changed under the limited plant input, It is expermentally verified that the speed response has much improved performance, such as no overshoot and fast settling time, and the maximmum plant input is also effectively utilized.

• 센서학회지
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• 제24권6호
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• pp.412-418
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• 2015

In this paper, a new method for obtaining PID coefficients which are essential to a temperature stabilization process has been proposed. This method starts from measuring the open loop transfer function of the module, then the closed loop transfer function embodying PID control can be produced based on this. Finally, the simulations using a few PID coefficients and the performance analysis for those results provide the best PID coefficients which are effective in a fast setting to a target temperature, a less current needed, and less deviation from steady state. The measurement using the derived PID coefficients, $K_p=1.6$,$K_i=0.8$,$K_d=0.3$ showed $T_s=7.4[sec]$, %OS = 16, and stabilization within ${\pm}0.02[^{\circ}C]$ for several hours. In addition to light sources like SOA, the proposed method can be utilized for any device needs temperature stabilization.

• 한국정밀공학회지
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• 제21권7호
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• pp.107-114
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• 2004

This paper presents a two-time scale approach for vibration reduction of a high speed Cartesian manipulator. High speed manipulators would be subject to mechanical vibration due to high inertia forces acting on linkages. To achieve high throughput capability, such motion induced vibration would have to be damped quickly, to reduce settling time of the manipulator end-effector. This paper develops a two-time scale model fer a structurally-flexible Cartesian manipulator. Based on the two-time scale model, a composite controller consisting of a computed torque method for the slow time-scale rigid body subsystem, and a linear quadratic state-feedback regulator for the fast time-scale flexible subsystem, is designed. Simulation results show that the proposed two time-scale controller yields good performance in attenuating structural vibration arising due to excitation from inertial forces.

• 전자공학회논문지C
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• 제36C권8호
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• pp.10-21
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• 1999

본 논문에서는 12비트의 해상도와 65MHz의 변환속도를 가지면서 단일 3.3V의 공급전압으로 동작하는 전류 셀 매트릭스 구조의 CMOS D/A 변환기를 제안하였다. 설계된 CMOS D/A 변환기는 우수한 단조증가성과 빠른 정착시간을 가지는 전류 셀 매트릭스 구조의 장점을 이용하면서 기존의 D/A 변환기의 전류셀 간의 문턱전압의 부정합과 접지선의 전압 강하에 의한 오차를 감소시키기 위해 트리 구조 바이어스 회로, 대칭적 접지선 연결, 캐스코드 전류 스위치를 사용하여 구현되었다. 설계된 전류 셀 매트릭스 12비트 D/A 변환기를 $0.6{\mu}m$ CMOS n-well 공정을 이용하여 제작하였다. 제작된 DAC칩을 +3.3V 단일 공급전원을 이용하여 측정한 결과, 정착시간이 20nsec로써 50MHz의 변환속도와 35.6mW의 전력소모를 나타내었다. 또한 측정된 SNR, DNL은 각각 55 dB, ${\pm}0.5LSB$,${\pm}2LSB$를 나타내었다.

• Journal of the korean society of oceanography
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• 제38권1호
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• pp.1-10
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• 2003

A time-series sediment trap was deployed at a depth of 1034 m in the eastern Bransfield Strait from December 25, 1998 to December 24, 1999. Particle fluxes showed large seasonal variation; about 99% of the annual total mass flux (49 g m/sup -2/) was collected during the austral summer and fall (January-March). Settling particles consisted primarily of biogenic silica, organic carbon, calcium carbonate, and lithogenic material. Biogenic silica and lithogenic material predominated settling particles, comprising 36% and 30% of the total mass flux, respectively, followed by organic carbon, 11% and calcium carbonate, merely 0.6%. The annual organic carbon flux was 5.4 g C m/sup -2/ at 1000 m in the eastern Bransfield Strait, which is greater than the central Strait flux. The relatively lower flux of organic carbon in the central Bransfield Strait may be caused by a stronger surface current in this region. Organic carbon flux estimates in the eastern Bransfield Strait are the highest in the Southern Ocean, perhaps because of the fast sinking of fecal pellets, which leads to less decomposition of organic material in the water column. Approximately 5.8% of the organic carbon produced on the surface in the eastern Bransfield Strait is exported down to 1000 m; this percentage exceeds the maximum EF/sub 1000/ values observed in the Atlantic and Southern Oceans. The eastern Bransfield Strait appears to be the most important site of organic carbon export to the deep sea in the Southern Ocean.

• 전자공학회논문지C
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• 제35C권6호
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• pp.56-66
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• 1998

본 논문은 비최소 위상 시스템을 보다 효율적으로 제어하기 위하여 기존의 PID 타입의 선형 제어기와 병렬적으로 구성된 신경망 제어기의 구성에 대하여 다룬다. 제안된 제어기의 제어 목표는 비최소 위상 시스템의 제어의 경우 흔히 나타나는 언더슛 현상을 최소화하면서 설정된 시스템 응답과의 응답 오차가 최소화하는 것이다. 전체 비용 함수는 고려된 두 가지의 개별 목적 함수간의 선형 합으로 이루어 진다. 신경망 제어기는 주어진 전체 제어 시간 동안의 제어 성능을 광역 평가를 통하여 주어진 전체 비용 함수를 최소화하는 최적 제어기를 구성하도록 진화 프로그래밍을 이용하여 off-line으로 학습된다. 일반적인 컴퓨터 모의 실험으로 계단 신호 응답에서 나타나는 빠른 settling 시간, 작은 언더슛과 오버슛과 같은 제어 성능 향상의 관점에서 기존의 선형 제어 시스템의 성능에 비해 훨씬 효과적이라는 것을 보인다. 또한, 파렛토(pareto) 다중 최적화 개념을 도입하여 선형 합으로 이루어진 비용 함수 최적화의 한계성과 문제점을 극복한다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 1999년도 추계종합학술대회
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• pp.161-166
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• 1999

이동 통신의 세계적 흐름은 디지털화, 고속화 그리고 대용량화의 추세로 나아가고 있다. 또한 한정된 주파수 자원을 효율적으로 이용하기 위하여 대역확산 방식이 그 주를 이루고 있다. 본 연구에서는 고속 주파수도약 방식을 이용하였다. 잡음 등의 여러 가지 문제점을 가지고 있는 PLL(Phase Lock Loop) 대신, PLL의 단점을 최소화할 수 있는 디지털 소자인 직접 디지털 주파수합성기(DDS : Direct Digital Synthesizer)를 사용하여 FFH 시스템 송신부의 주파수합성기를 설계하였다. PLL를 이용하여 고속 주파수 도약시스템을 설계하는 경우, PLL의 settling time의 설정과 요구되는 RF대역폭등의 설계사양을 만족시키기가 어려우며 평형변조기 사용에 의한 회로의 복잡성으로 인한 제약이 따르게 된다. 본 연구에서는 DDS를 이용하여 고속 주파수도약 시스템을 설계하기 위한 성능평가에 대하여 연구하였으며, 오율 개선의 해석과 도약율 1M hps, 5MHz RF 대역폭의 고속 주파수 도약이 가능한 시스템을 설계하고 성능을 평가하였다.

• 제어로봇시스템학회논문지
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• 제5권8호
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• pp.889-897
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• 1999

This paper deals with a problem searching a target transfer function to meet the time-domain specifications for feedback system with given plant transfer function. For the Type I system, we first define three forms of transient response to unit step input, which are named by F, M, S-type. These are charaacterized as follows ; F-type has fast initial response and slow approach to the steady sate after reaching at 90% of the steady state value, S-type has slow initial response but fast approach to the steady state, and M-type is denoted by highly smooth response between F-type and S-type. Three prototypes corresponding to each form are proposed, time. For the order $n{\geq}4$, after determining admissible root structures of target characteristic polynomials empirically and expressing such polynomial coefficients by using special parameters ${\gamma}_i$ and $\epsilon$, the optimal prototypes that minimize the integral of the squared of the modified errors(ISME) have been obtained. Since the step responses of these prototypes have almost same wave forms irrespective to the order, the desired settling time or the rise time can be converted into the equibalent time constant $\tau$ and thus it is easy to obtain a target transfer function. It is shown through a design example that the present prototype is very useful for meeting the time-domain specifications and has been compared with different methods with a viewpoint of pertinence.