• 한국광학회지
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• 제4권4호
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• pp.464-473
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• 1993

본 논문에서는 광섬유에 아르곤 레이저 빔이 입사될 때 생기는 위상격자 형성에 관한 역학을 다룬다. 간단한 쌍광자 표백모델(two-photon bleaching model)을 이용하여 위상격자가 시간이 지남에 따라 이상적인(ideal) 격자로 자기조직됨(self-organized)을 보인다. 광섬유의 각점에서의 시간에 따른 상태전개는 하나의 보편 매개변수(universial parameter)에 의해 나타내어지고 또한 이 광섬유계를 기술하는 연립편미분 방정식이 이 매개변수에 의해 연립 상 미분 방정식으로 간소화 된다. 이 연립 상 미분 방정식을 이용하여 위상격자가 자라나는 상태는 한 고정점(a fixed point)를 향해 가는 과정이고 이 고정점은 완벽히 위상맞춤(phase-matched)된 격자에 해당된다는 것을 보인다.

• Journal of Advanced Marine Engineering and Technology
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• 제27권6호
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• pp.696-703
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• 2003

A photovoltaic power generation system is an infinite and clean energy system. Recently. because of the realization of high efficiency and low cost PV modules, the studies on the PV system have extensively increased. In this paper. we present an online scheme for parameter estimation of solar cell, based on the model adjustment technique and a real-coded genetic algorithm(RCGA). The ideal diode model and the diode model with series and shunt resistors are used to estimate their parameters, Simulation works using field data in the form of a V-I characteristic curve are carried out to demonstrate the effectiveness of the proposed method.

• 산업경영시스템학회지
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• 제19권39호
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• pp.243-254
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• 1996

In this study, a model and an analysis method for parameter design is presented a linear relation between the input signal and the ideal value of a performance characteristic. Furthermore, There presented a new performance measure, expected quality loss after adjustment, which is proved to be equivalent to Taguchi's SN ratio approximately. On the basis of this, a two-step optimization procedure is proposed for parameter design considering the signal factor and the quality characteristics with continuous variable. Proposed procedure and Taguchi two-stage procedure are compared.

• Korean Journal of Chemical Engineering
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• 제35권11호
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• pp.2269-2282
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• 2018

Mixed micelle formation behavior of cationic surfactant-cetyltrimethylammonium bromide (CTAB) and anionic surfactant sodium dodecyl sulfate (SDS) in aqueous as well as in urea medium from 303.15 K to 323.15 K at 5 K interval was carried out by conductometric method. The differences between the experimental values of critical micelle concentrations (cmc) and ideal critical micelle concentrations ($cmc^{id}$) illustrate the interaction between the amphiphiles studied. The values of micellar mole fraction ($X_1^{Rub}$ (Rubingh), $X_1^M$ (Motomura), $X_1^{Rod}$ (Rodenas) and $X_1^{id}$(ideal) of surfactant CTAB determined by different proposed models and outcome indicate high involvement of CTAB in SDS-CTAB mixed micellization, which enhance by means of the augment of mole fraction of CTAB. The negative value of interaction parameter (${\beta}$) showed an attractive interaction involving CTAB and SDS. Activity coefficients were less than unity in all case, which also reveals the presence of interaction between CTAB & SDS. The negative ${\Delta}G^0_m$ values imply the spontaneous mixed micellization phenomenon. The attained values of ${\Delta}H^0_m$ were positive at inferior temperature, while negative at superior temperature. The negative ${\Delta}H^0_m$ values in urea ($NH_2CONH_2$) medium illustrate exothermic micellization process. The magnitudes of ${\Delta}S^0_m$ were positive in almost all cases. The excess free energy of mixed micelle formation (${\Delta}G_{ex}$) was found to be negative, which indicates the stability of mixed micelle as compared to the individual's components micelles.

• 대한기계학회논문집B
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• 제22권11호
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• pp.1635-1646
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• 1998

The present study investigated the effects of geometric parameters considered on the performance of an automotive scroll compressor by assuming ideal, semi-real and real gases for R-134a. The geometric parameters were center thickness of scroll, height of scroll and the size of discharge port. Fourth-order Runge-Kutta method was applied to solve the thermodynamic equations, leaking rate equation and the equation of motion of discharge valve for ideal, semi-real, and real gases. The volumetric and adiabatic efficiencies for semi-real and real gases differed little, but those for ideal gas differed by 18% and 25% compared with those for real gas at 2,000rpm. The volumetric efficiency changed little as the design angle of scroll (${\gamma}$) changed, but the adiabatic efficiency at ${\gamma}$ of $34^{\circ}$ was higher by 2.4% than that of $147^{\circ}$ for 2,000rpm. The volumetric and adiabatic efficiencies at scroll height of 29.8mm were higher by 1.7% and 2.8% than those of 65.8mm. The volumetric efficiency changed little as the size of discharge port changed, but the adiabatic efficiency increased a little as the size of discharge port decreased.

• Journal of Power Electronics
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• 제17권5호
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• pp.1268-1277
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• 2017

Three-phase pulse width modulation (PWM) rectifiers are usually designed under the assumption of ideal ac power supply and input inductance. However, non-ideal circuit parameters may lead to a voltage collapse of PWM rectifiers. This paper investigates the mechanism of voltage collapse in three-phase PWM rectifiers. An analytical stability boundary expression is derived by analyzing the equilibrium point of the averaging state space model, which can not only accurately locate the voltage collapse boundary in the circuit parameter domain, but also reveal the essential characteristic of the voltage collapse. Results are obtained and compared with those of the trial-error method and the Jacobian method. Based on the analysis results, the system parameters can be divided into two categories. One of these categories affects the critical point, and other affects only the instability process. Furthermore, an effective control strategy is proposed to prevent a vulnerable system from being driven into the instability region. The analysis results are verified by the experiments.

• Structural Engineering and Mechanics
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• 제13권4호
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• pp.355-368
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• 2002

In this paper, we address the numerical investigation on the effect of liquid compressibility onto the natural frequency of liquid-filled containers. Traditionally the liquid motion has been treated as an ideal fluid motion. However, from the numerical experiments for the axisymmetrical free-vibration of cylindrical liquid-storage tanks, we found that the relative difference in natural frequencies between ideal and compressible motions becomes remarkable, as the slenderness of tank or the relative liquid-fill height becomes larger. Therefore, in such cases of dynamic systems, the liquid compressibility becomes an important parameter, for the accurate vibration analysis. For the free-vibration analysis of compressible liquid-structure interaction we employed the coupled finite element formulation expressed in terms of the acoustic wave pressure and the structure deformation.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.859-864
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• 1998

Compact and small size, reliable and failsafe operation and low cost featuring fault current limiter causing the designer to take a close look into the use of passive fault current limiter(FCL) for the protection of power semiconductor devices in power electronic systems. This paper has identified the main parameters responsible for the development of ideal passive magnetic current limiter. The effect of those parameters on the range of operation and the voltage-current characteristics of the magnetic current limiter has been studied using tableau approach. Desirable characteristics are discussed and the simulation results are presented.

• EDISON SW 활용 경진대회 논문집
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• 제5회(2016년)
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• pp.513-515
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• 2016

There are various walking devices based on Theo Jansen mechanism. And these systems controlled by complicate equations. So we decided to optimize the design of walking device with two points of view. The device is required to ensure stability while maintaining the high speed. To simplify the control system, we applied trigonometric ratio with ideal Jansen trajectory. As a result, we were able to draw the connection between height of barrier and Ground Length (GL). Also we could change traveling distance and Ground Angle Coefficient (GAC) by shifting the position of the joints. Through controlling these parameter, we can analyze stability and speed of the device. Ultimately, we develop the device that can walk more efficiently by the optimization process.

• 대한기계학회논문집A
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• 제26권7호
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• pp.1453-1460
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• 2002

Creep-fatigue crack growth models have been proposed employing $(C_t)_{avg}$ as a crack tip parameter characterizing the time-dependent crack growth. The basic assumptions made in these previous models were ideal creep reversal conditions such as no creep reversal and complete creep reversal condition. Due to this assumption, the applicability of the models was limited since they did not consider partial creep reversal condition which is usually observed in many engineering metals at high temperature. In this paper the creep reversal parameter, Temperature;$C_R$, which was defined by Grover, is critically evaluated to quantity the extent of partial creep reversal at the crack tip. This approach does not rely on any simplifying assumptions regarding the extent of the amount of creep reversal during the unloading part of a trapezoidal fatigue cycles. It is shown that the $(C_t)_{avg}$ value calculated for 9Cr steel agrees well with the experimentally measured one. It is argued that the extent of improvement is not significant when the result is compared with that of the conventional model which has an assumption of full creep reversal behavior.