• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 26-27 Oct. 1990
• /
• pp.550-555
• /
• 1990

In the VSS control, reaching phase and chattering problem are the main disadvantages. A simple nonlinear sliding surface is proposed to cope with the reaching phase. The chattering problem is alleviated by almost continuous control with the compensation using the infinite closed loop.

• 대한수학회논문집
• /
• 제11권3호
• /
• pp.695-706
• /
• 1996

In the control system $ \dot{x} = f(t,x(t)) + g(t,x(t))\dot{u}, x(0) = \bar{x}, t \in [0,T], $ this paper shows that the map from u with $L^1(m)$-topology to $x_u$ with $L^1(\mu)$-topology is Lipschitz continuous where f is $C^1$, $\mu$ is the Stieltjes measure derived from the function g which is not smooth in the variable t and $x_u$ is the solution of the above system corresponding to u under the assumption that $\dot{u}$ is bounded.

• 가정과삶의질연구
• /
• 제31권5호
• /
• pp.125-141
• /
• 2013

This research aims to integrate study results through a meta-analysis of previous studies on the variables related with social support for female marriage immigrants. Based on the results, this study established the foundation of an integrated social support system for female marriage immigrants which considers both the functional perspective and structural perspective of social support, and suggested plans for an efficient support system. All social support was positively associated with female marriage immigrants marriage life, child-rearing behavior and attitude, reduction of stress and depression and psychological stability. In relation to the effect size of each variable related with all social support, the marriage variable had the biggest relationship with it, followed by the parenting variable, the psychological variable and the stress variable in that order. With reference to the relationship with related variables according to the sub-domain of social support, from the structural perspective, spousale support showed a high relationship with the marriage variable and the stress variable. It was also especially, very highly related with the marriage variable. In addition, a married woman's family support and expert support had an intermediate relationship with the marriage variable, and the husband's family support and friend support had a low relationship with it. From the functional perspective, material support had a very high relationship with the marriage variable, whereas it had a low relationship with the stress variable and the psychological variable. Emotional support was also highly related with marriage variable, but showed an intermediate or low relationship with the psychological variable and the stress variable. On the other hand, informational support displayed an intermediate relationship with the stress variable and the psychological variable, and a high relationship with the marriage variable. Lastly, evaluative support had a high relationship with the marriage variable and the psychological variable. Based on these results, this study proposed plans for an integrated social support system as follows. First, education ought to be provided for the spouses, and support for marital adjustment should be offered. Second, there plans should be made for continuous bonding with the family of origin, and support should be given to address changes in awareness of the relationship with the husband's parents. Third, it is required to revitalize the local community and self-help groups, and provide the female marriage immigrants with opportunities to participate in social activities.

• 품질경영학회지
• /
• 제30권3호
• /
• pp.150-167
• /
• 2002

Normative theory suggests that control systems should be designed to complement management's objectives and strategies. However, few empirical studies have focused on how control systems have been modified to complement new manufacturing techniques, such as zero-defect strategy. The major purpose of this study is to examine the effects of the attributes of quality strategy and control system on performance. The previous studies have subdivided quality strategy into the ECL(economic conformance level) and ZD(zero-defect) strategy. To accomplish the purpose, this study empirically analysed the data based on the questionnaires from manufacturing department personnel of 67 Korean companies. The major results are as follows. The companies that had implemented the ZD strategy and its control system outperformed the companies that had implemented ECL strategy. Also, the ZD strategy differs from ECL strategy in control system, the criteria of performance evaluation and feedback frequence variable. There is no difference in quality performance monitoring and communication variable. From this results, although many companies have strived for continuous improvement of quality, it was restricted in improvement activities that dont's required much investment cost, quality performance monitoring and communication.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 하계학술대회 논문집 D
• /
• pp.2661-2663
• /
• 2000

In general, to reduce chattering in sliding mode control, a boundary layer around the sliding surface is used, and a continuous control is applied within the boundary. In this paper we propose the design method of sliding mode controller with sliding sector. To do this, the variable structure controller is designed for the linear system with uncertainty using sliding sector. The control law designed in the paper transfers the system state from outside to the inside of the sliding sector and ensures that some norm of the system state keeps decreasing.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2007년도 춘계학술대회B
• /
• pp.3311-3316
• /
• 2007

To analyze the influence of valve overlap period on a backfire occurrence, the single cylinder research engine with MCVVT(Mechanical Continuous Variable Valve Timing) system is developed and backfire limit equivalence ratio defined as fuel-air ratio equivalence ratio at which backfire occurs is examined according to various valve overlap period. The MCVVT is the system to control valve overlap period by mechanical device. It is estimated that the lower valve overlap period has the higher backfire limit equivalence ratio though the same energy is supplied. When the valve overlap period is changed from 30$^{circ}$ CA to 0$^{circ}$ CA, backfire limit equivalence ratio is increased 74%, approximately. It means that valve overlap period is concern in backfire occurrence, and may be one of the methods for controlling back fire occurred in a $H_2$ engine.

• 한국수소및신에너지학회논문집
• /
• 제17권3호
• /
• pp.255-262
• /
• 2006

To develop a hydrogen fueled engine with external mixture which uses in high reliability, low cost and low pressure, the single cylinder research engine with MCVVT(Mechanical Continuous Variable Valve Timing) system is developed and its basic characteristics analyzed. The MCVVT developed has high reliability and the valve timing change is possible in wide range continuously. Though the mechanical loss due to MCVVT system is increased a little, back-fire suppression research for valve overlap period is no difficulty. It's also confirmed that the hydrogen-fueled engine has lower torque and is possible high lean burn. As fuel-air equivalence ratio is high, as thermal efficiency is remarkable increasing.

• 유공압시스템학회논문집
• /
• 제5권4호
• /
• pp.1-9
• /
• 2008

In this paper, an energy regeneration algorithm is proposed to make the maximum use of the regenerative braking energy for a parallel hybrid electric vehicle(HEV) equipped with a continuous variable transmission(CVT). The regenerative algorithm is developed by considering the battery state of charge(SOC), vehicle velocity and motor capacity. The hydraulic module consists of a reducing valve and a power unit to supply the front wheel brake pressure according to the control algorithm. In order to evaluate the performance of the regenerative braking algorithm and the hydraulic module, a hardware-in-the-loop simulation (HILS) is performed. In the HILS system, the brake system consists of four wheel brakes and the hydraulic module. Dynamic characteristics of the HEV are simulated using an HEV simulator. In the HEV simulator, each element of the HEV powertrain such as internal combustion engine, motor, battery and CVT is modelled using MATLAB/$Simulink^{(R)}$. In the HILS, a driver operates the brake pedal with his or her foot while the vehicle speed is displayed on the monitor in real time. It is found from the HILS that the regenerative braking algorithm and the hydraulic module suggested in this paper provide a satisfactory braking performance in tracking the driving schedule and maintaining the battery state of charge.

• 한국경영과학회지
• /
• 제23권1호
• /
• pp.43-65
• /
• 1998

This paper develops a two-echelon inventory model with time-weighted partial backorders. The presented model assumed to follow continuous review (Q. r) policy for both the retailers and the central warehouse under stochastic demand. A heuristic method to find an optimum-tending solution for total variable system cost per year incurred at the central warehouse and retailers in a system is suggested. To show the usefulness of the above model, numericla examples are illustrated for verification and validation purpose.

• 한국조명전기설비학회지:조명전기설비
• /
• 제9권4호
• /
• pp.55-61
• /
• 1995

Variable structure control (VSC) can be used for the control of power plants required stability and robustness such as elevator control. It has no overshoot and is insensitive to parameter variations and disturbances in the sliding mode where the system structure is changed with the sliding surface in the center. But in the real system, VSC has a high frequency chattering which has a bad influence upon the control system proformances. In this paper, to alleviate the high frequency chattering, a binary controller (BC) with inertial type external loop is implemented by DSP and applied to position control of brushless DC motor. Binary controller has external loop to generate the continuous control input with the flexible variation of primary loop gain. Thus it has the property of chattering alleviation in addition to advantages of the conventional variable structure control.