• 오토저널
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• 제15권1호
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• pp.67-72
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• 1993

Wall wetting phenomenon in the intake port of an MPI engine was investigated with different kinds of injectors by an A/F step response test and analysis was done based on the simple wall wetting model to find out a certain correlation between wall wetting and A/F variations. It was found that (1) At fully warmed condition of 90.deg.C water temperature, around 40-60% of injected fuel was wall wetted, (2) At cold condition of 45.deg.C Water temperature, around 68-80% of injected fuel was wall wetted, and (3) A/F variations during acceleration and deceleration were influenced by the wetting area, the fuel droplet size, and the amount of wall wetting fuel.

• 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.

• 대한조선학회논문집
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• 제35권1호
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• pp.72-79
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• 1998

탄소성 보구조물의 정적 변형은 하중의 크기가 소성붕괴력 $F_c$ 보다 작게 될 때만 적용된다. 그러나 충격이나 폭발 상황에서 소성 붕괴력을 넘는 하중을 받는 보 구조물은 정적인 탄소성 변형과 다른 응답특성을 보이게 된다. 본 논문에서는 간단한 구조 모델로서 강-완전 소성 외팔보를 도입하여 소성 붕괴력보다 큰 하중 ($F>F_c$)이 작용하였을 때 구조물의 응답특성을 연구하였다. 계단 하중(step loading)이 가해졌을 경우에 보의 운동을 무차원하여 계산하고 이 결과를 사각형파 하중(rectangular force pulse)이 가해지는 경우에도 이용하여 해석하였다. 해석 수행 결과 무차원화된 힘을 나타내는 파라메타인 $f{\equiv}F/F_c$의 함수로서 보의 변위를 나타낼 수 있음을 확인하였다.

• Archives of Pharmacal Research
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• 제21권1호
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• pp.35-40
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• 1998

Human cytochrome P450 4F2 shows high regioselectivity in hydroxylation of stearic acid and leukotriene $ B_4.$ As a first step of its regulation study, human cytochrome P450 4F2 genomic DNA was isolated from liver of a person who was administered clofibrate for 10 years. From Southern hybridization, restriction enzyme digestion and sequencing experiments, isolated genomic DNA fragment was found to contain around 32 Kb DNA and more than 20 Kb of $5^I$ end regulatory region. Sequences of the structural gene region revealed exon 1 and exon 2. Further regulation studies would elucidate the feedback mechanisms of the oxidative degradation of fatty acids, inflammatory response and the clearance of leukotriene B4 in the liver. Furthermore, regulation study of this gene could explain the species difference in responses to peroxisome proliferator and help in the safety evaluation of peroxisome proliferating chemicals to human being.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.690-692
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• 2004

Differently from an existing analog control, because the digital control includes microprocessor basically, the digital control is enable to monitor internal parameters of DC-DC converter and to control output voltage remotely by communicating with a Windows based PC and also to monitor whether exact voltage is output or not. These things are impossible in an analog control. In this paper, a simple flyback converter is taken as a control target and is controlled by a microcontroller(TMS320F2812). This converter can make variable outputs 1.8V to 5V from 30V input voltage remotely in PC. Finally the response characteristics of a step reference voltage and in a steady state are experimented to verify the feasibility and the usefulness of this digital controlled converter.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2274-2277
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• 2003

A cylindrical permanent magnet inside the four-phase permanent magnet (PM) stepping motor is employed as the rotor. The stator has four teeth around, which its coils are wound. The mode of excitation can be classified into 3 modes: single-phase excitation, two-phase excitation and ministep excitation. The ministep drive is a method to subdivide one step into several small steps by means of electronics. The paper presents the programmable ministep technique drive. This technique decodes the results obtained from the counter to locate the data in Read Only Memory (ROM). The Sinusoidal Pulse Width Modulation (SPWM) is transformed to binary file and saved to the ROM. The experiment is performed with the four-phase PM stepping motor and drives from a two-phase programmable sinusoidal ministep signal, instead of square wave. The results show that the performances of the proposed programmable ministep technique drive have high efficiency, smooth step motion, and high speed response. Moreover, the resolution of sinusoidal ministep signal can be controlled by the input frequency (f command).

• 한국정보통신학회논문지
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• 제20권6호
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• pp.1154-1162
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• 2016

본 논문에서는 이진 가중치 전류 기법을 이용한 고속 디지털 LDO(Low Dropout) 레귤레이터를 제안했다. 기존의 디지털 LDO는 일정량의 전류를 한 단계씩 제어하기 때문에 응답하는데 오랜 시간이 걸리며, 링잉 문제가 발생하게 된다. 이중 가중치 전류 기법은 링잉 문제를 제거함으로써 출력전압이 빠르게 안정화되도록 한다. 출력전압이 목표 전압에 안정적으로 도달하면, 디지털 LDO의 동작을 멈추는 프리즈 모드를 추가했다. 제안된 고속 응답 디지털 LDO는 출력 전원 전압이 급격히 바뀌는 시스템에서 응답속도가 느린 DC-DC 변환기와 함께 사용되어 출력전압을 빠르게 변하도록 한다. 제안된 디지털 LDO는 기존의 양방향 시프트 레지스터보다 면적이 56% 감소했고, 리플전압이 87% 감소했다. 제안된 디지털 컨트롤러는 $0.18{\mu}F$ CMOS 공정으로 제작되었다. $1{\mu}F$의 출력 캐패시터에서 정착시간이 $3.1{\mu}F$이고, 리플전압은 6.2mV 였다.

• Structural Engineering and Mechanics
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• 제3권2호
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• pp.185-192
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• 1995

A numerical algorithm for plane stress and shell elasto-plasticity is presented in this paper. The proposed strain decomposition (SD) algorithm is an elastic predictor/plastic corrector algorithm, and in the context of operator splitting, is a return mapping algorithm. However, it differs significantly from other return mapping algorithms in that only the necessary response functions are used without invoking their gradients, and the stress increment is updated only at the end of the time step. This makes the proposed SD algorithm more suitable for materials with complex yield surfaces and will guard against error accumulation during the time step. Comparative analyses of structural systems using the proposed strain decomposition (SD) algorithm and the iterative radial return (IRR) algorithm are presented. The results demonstrate the accuracy and usefulness of the proposed algorithm.

• Wind and Structures
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• 제15권3호
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• pp.247-261
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• 2012

Some numerical investigations are presented concerning the response of a given plate under turbulence driven excitations. Three different input loads are simulated according to the wall pressure distributions derived from the models proposed by Corcos, Efimtsov and Chase, respectively. Modal solutions (finite element based) are used for building the modal stochastic responses in the sub-critical aerodynamic frequency range. The parametric investigations concern two different values of the structural damping and three values of the boundary layer thickness. A final comparison with available experimental data is also discussed. The results demonstrate that the selection of the adequate TBL input model is still the most critical step in order to get a good prediction.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.215-220
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• 2002

Recently, linear motor has been developed for linear motion of machine tools. Linear motor is useful to design the linear motion, high speed and high accuracy, because of the simple system not required the additional mechanical part such as coupling and ballscrew. This paper tested performance of linear motor relevant to motioning and positioning table such as F.R.F., step response and positional accuracy Linear motion system using linear motor requires the effective cooling system because it cause to decrease the positional error and to protect the motor coil. Therefore the positional error measurement was made to evaluate the effect of the temperature variation.