• International Journal of Aeronautical and Space Sciences
• /
• 제16권1호
• /
• pp.102-109
• /
• 2015

In Korea, Lunar exploration program has been prepared with the aim of launching in the 2020's. As a part of it, a lunar lander demonstrator was developed, which was the model for verifying the system such as structure, propulsion, and control system, before launching into the deep space. This paper deals with the path tracking performance of the lunar lander demonstrator with respect to the thruster controller based on Pulse Width Pulse Frequency Modulator (PWPFM) and Pulse Width Modulator (PWM). First, we derived equations of motion, considering the allocation of the thrusters, and designed the path tracking controller based on Euler angle. The signal generated from the path tracking controller is continuous, so PWPFM and PWM modulator are adopted for generating ON/OFF signal. Finally, MATLAB simulation is performed for evaluating the path tracking ability. We compared the path tracking performances of PWPFM and PWM based thrust controller, using performance measures such as the total impulse and the position error with respect to the desired path.

• 한국전기전자재료학회논문지
• /
• 제21권4호
• /
• pp.289-295
• /
• 2008

In this paper, we designed the off-line PWM(Pulse width modulation) control IC for flyback type power converter to reduce the standby power consumption. In normal state, this off-line PWM IC generates the output pulse with $40\sim60kHz$ frequency and duty ratio of $20\sim88%$. When SMPS operates in standby mode, this IC generates the output pulse with 33kHz frequency and duty ratio of 1 %. SPICE simulation was performed to verify the standby power consumption of the power converter with designed of-line PWM IC. Power converter with designed off-line PWM IC consumes less than 0.3W when it operates in standby mode condition.

• 대한전자공학회논문지
• /
• 제25권2호
• /
• pp.204-210
• /
• 1988

The residue number system offers the possibility of high-speed operation and error detection/correction because of the separability of arithmetic operations on each digit. A compact residue arithmetic module named the self-checking pulse-train residue arithmetic circuit is effectively employed as the basic module, and an efficient error detection/correction algorithm in which error detection is performed in each basic module and error correction is performed based on the parallelism of residue arithmetic is also employed. In this case, the error correcting circuit is imposed in series to non-redundant system. This design method has an advantage of compact hardware. Following the proposed method, a 2nd-order recursive fault-tolerant digital filter is practically implemented, and its fault-tolerant ability is proved by noise injection testing.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1998년도 하계학술대회 논문집 G
• /
• pp.2467-2469
• /
• 1998

We examine the performance of high-speed non-directed infrared links using pulse-position modulation (PPM) with trellis-coded modulation (TCM) to mitigate the effects of multipath-induced intersymbol interference(ISI) on such links. Using the measured characteristics of multipath indoor infrared channels, we calculate BER curves and ISI power penalties for maximum-likelihood sequence detection of 8-PPM links using rate-2/3 trellis codes operation at 10 and 30Mb/s. Our results indicate that the suggested decoder of PPM with TCM is a very promising decoder on high-speed non-directed infrared channels.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1998년도 하계학술대회 논문집 A
• /
• pp.15-17
• /
• 1998

The position of LPM's mover can be estimated by the equivalent inductance variation with the mover's displacement. Hence, in this paper, we obtained the position detection signal by the calculation of equivalent inductance variation using the winding of linear pulse motor. And the various parameters for calculation of equivalent inductance variation were obtained by the design specification and finite element analysis of linear pulse motor. With this position signal, it is possible to calculate the driving numbers of steps, to confirm the state of step out and to determine the optimal switching angle, etc.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 하계학술대회 논문집 C
• /
• pp.1533-1535
• /
• 2000

The design and fabrication technologies of pulse power reversely switched-on dynistor have been developed 1200V/120kA pulse power reversely switched-on dynistor device have been designed by analytically and numerically using commercial modeling S/W The important characteristics of reversely switched-on dynistors are breakover voltage $V_{BO}$, commutative peak voltage before steady state $V_m$, on-state voltage in steady state $V_o$, turn-off time $t_q$, dV/dt capability.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2002년도 하계종합학술대회 논문집(1)
• /
• pp.263-266
• /
• 2002

Many methods have been Proposed to reduce the PAPR of the OFDM signal. Among them a method that uses the time waveform of the different sub-carriers. The method is referred to as pulse shaping and it works with arbitrary number of sub-carriers and my type of base-band linear modulation. It has been shown, using this technique, that it is possible to design a set of time waveforms that reduce the PAPR of the OFDM transmitted signal and improve its power spectrum simultaneously. In this paper, we investigate the effect of some of these sets of time waveforms on the OFDM system performance in terms of Bit Error Rate (BER).

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 하계학술대회 논문집 D
• /
• pp.2252-2254
• /
• 2001

This paper proposes a algebraic parameter determination of MRAC (Model Reference Adaptive Control) controller using block Pulse functions and block Pulse function's differential operation. Generally, adaption is performed by solving differential equations which describe adaptive low for updating controller parameter. The proposes algorithm transforms differential equations into algebraic equation, which can be solved much more easily in a recursive manner. We believe that proposes methods are very attractive and proper for parameter estimation of MRAC controller on account of its simplicity and computational convergence.

• 조명전기설비학회논문지
• /
• 제25권8호
• /
• pp.20-29
• /
• 2011

This paper presents an improved phase-shift pulse-width modulation (PWM) full-bridge converter using a blocking capacitor. As the proposed converter reduces the circulation energy by inserting only one series blocking capacitor at the primary side of the conventional phase-shift PWM full-bridge converter structure, it improves the operation characteristics of the conventional converter. In this paper, first, the operation of conventional phase-shift PWM full-bridge converter is roughly reviewed, and then the operational principle of the proposed converter is classified and explained by each mode. After that, a prototype design example based on the operational principle is shown. Then, the improved operation characteristics of the proposed converter are actually verified through the experimental results.

• 전기의세계
• /
• 제28권1호
• /
• pp.59-66
• /
• 1979

The linearized models on per for mance dynamics of the pulse motor have been already proposed by many others. These models exhibit certain advantages of their own because of their simple formulation, but in many cases the models are proved to be inadequate for further accurate analysis of the motor dynamics, owing to impractical and rather rough assumptions in the derivation. In this study a dynamic state transition model is induced, using the equivalent circuit obtained from the operating principle of the variable reluctance pulse motor which turns out to be nonlinear equation. This nonlinear dynamic state equation is numerically analysed by the use of UNIVAC System/3(OS/3) digital computer at hand. In the course of the dynamic analysis of the performance characteristics of a testing motor, dependance of the inertia of rotor and load, the coefficient of viscous friction between rotor and housing, and the winding resistance of the stator is discussed and a comparative study of the machine constants is carried on as related to the design problem of the motor.