• 한국정밀공학회지
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• 제31권3호
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• pp.253-259
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• 2014

This study proposes a map-based control method to improve a vehicle's lateral stability, and the performance of the proposed method is compared with that of the conventional model-referenced control method. Model-referenced control uses the sliding mode method to determine the compensated yaw moment; in contrast, the proposed map-based control uses the compensated yaw moment map acquired by vehicle stability analysis. The vehicle stability region is calculated by a topological method based on the trajectory reversal method. The performances of model-referenced control and map-based control are compared under various road conditions and driving inputs. Model-referenced control uses a control input to satisfy the linear reference model, and it generates unnecessary tire lateral forces that may lead to worse performance than an uncontrolled vehicle with step steering input on a road with low friction coefficient. The simulation results show that map-based control provides better stability than model-referenced control.

• 한국지능시스템학회논문지
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• 제7권5호
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• pp.14-20
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• 1997

This paper proposes a new design method for the SMC-type FLC and shows that a SMC-type LFC is an extension of the SMC with BL. The conventional SMC-type FLC uses error and change-of-error as inputs of the FLC and generates the absolute value of a switching magnitude. Then, the fuzzy rule table is constructed on a two-dimensional space of the phase plane and has commonly the skew symmetric property. In this paper, we introduce a new variable, signed distance, from the skew symmetric property of the rule table. And thd variable becomes only a fuzzy variable that is used to generate the control input of a SMC-type FLC. that is, we design a new SMC-type FLC that uses a signed distance and a control input as the variables representing the contents of the rule-antecedent and the rule-con-sequent, respectively. Then the number of total rules is reduced and the control performance is almost the same as that of the conventional SMC-type FLC. Additionally, we derive the control law of the ordinary SMC with BL from a new SMC-type FLC. Namely, we show that a FLC is an extension of the SMC with BL.

• International Journal of Ocean System Engineering
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• 제1권1호
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• pp.9-15
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• 2011

This study examined the relationship between the scarf angle and stress distribution, and estimated the strength recovery via a finite element analysis. The following conclusions were drawn from this study. Resin will fracture due to a tensile load with a high scarf angle, which is similar to the patch repair method. An applied stress can be loaded to a repaired laminate if the scarf angle is $5^{\circ}$. The Von-Mises stress increases with decreasing scarf angle, with the exception of a scarf angle of $30^{\circ}$, where the scarf angle can indicate the rates of shear and normal stresses. Strength recovery can be better if the scarf angle is decreased to a lower angle. However, scarf machining requires more time, a high skill level and considerable expense. Therefore, a scarf angle of $5^{\circ}$ is the most effective for a repair. These results may provide a guide for engineers wishing to formulate a standard for repair. The scarf angle needs to be carefully managed for a more efficient composite repair.

• Journal of Electrical Engineering and Technology
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• 제12권3호
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• pp.1271-1279
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• 2017

A highly accurate model-free controller is proposed for trajectory tracking control of robot manipulators. The proposed controller incorporates time-delay estimation (TDE) to estimate and cancel continuous nonlinearities of robot dynamics, and exploits fuzzy logic systems to suppress the effect of the TDE error, which is due to discontinuous nonlinearities such as friction. To this end, integral sliding mode is defined using desired error dynamics, and a Mamdani-type fuzzy inference system is constructed. As a result, the proposed controller achieves the desired error dynamics well. Implementation of the proposed controller is easy because the design of the controller is intuitive and straightforward, and calculations of the complex robot dynamics are not required. The tracking performance of the proposed controller is verified experimentally using a 3-degree of freedom PUMA-type robot manipulator.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.433-435
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• 1993

The purpose of this study is to propose a robust OFVSCS that have the robust properties against process parameter variations and external disturbances by extending the basic OFVSCS and to evaluate its control performances. The ROFVSCS is composed of dynamic switching surfaces and output feedback switching control inputs that are constructed by the use of the unknown vector modeling technique. With the proposed scheme. existence of sliding mode is guaranteed and any nonzero bias can be suppressed in the face of disturbances and process parameter variations as far as well-known matching condition is satisfied. Due to the fact that the ROFVSCS is driven by small number of measured information, the practical application of VSCS for the systems with unmeasurable states and for high order systems. that conventional schemes cannot be applied, is possible with the proposed scheme. It is noticeable that implementation cost or VSCS can be considerably reduced without sacrifice of control performances by adopting ROFVSCS since there is no need to measure the states with high measurement cost.

• 한국조명전기설비학회지:조명전기설비
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• 제7권4호
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• pp.51-58
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• 1993

리니어 직류 모터의 고속, 고정도 위치제어에 대하여 포물선형 스위칭 함수에 최단시간 제어 방식을 제안하였다.제안한 방식은 간단한 구성으로 최단시간 제어를 실현한기 위하여 뱅-뱅 제어의 절환을 위상면에 설정한 포물선형 스위칭 함수상에서 행하는 것이다. 그러나 시스템의 모델링 오차등에 의하여 슬라이딩 모드를 발생시키므로 최단시간 제어를 위해 반복실험에 의하여 1회의 절환에 의한 뱅-뱅 제어를 실현하였다. 그 후 궤환 제어에 의하여 리니어 직류모터를 목표점에 정지시켰다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제32회 추계학술대회 정기총회
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• pp.332-340
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• 2000

Friction properties of automotive brake pads containing different types of abrasivess were investigated. Five different abrasives, including o-quartz, magnesia, magnetite, alumina, zircon, were employed in this investigation and size effects of the abrasives on friction characteristics were also studied using 1, 50, 140$\mu\textrm{m}$ size zircon. Experimental results showed that the hardness and size of these abrasive particles were strongly related to friction behaviors and wear mechanisms. Harder and smaller abrasives showed higher friction coefficient and more wear. The surfaces of friction materials with different sizes of abrasives showed that two different modes of abrasion (two-body and three-body abrasion) appeared during sliding. Considering the above results, abrasive materials were thought to destroy transfer film and the extent of the destruction depends on the types and sizes of abrasive particles. A mechanism of the wear mode transition (two-body to three body abrasive motion) was suggested considering the binding energy and friction energy in terms of abrasive particle size.

• 한국항공우주학회지
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• 제49권10호
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• pp.821-828
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• 2021

쿼드로터는 다른 비행체에 비해 작고 가벼워서 바람과 같은 외란에 민감하다는 단점이 있다. 이 단점을 해결하기 위해 외란에 강인한 제어기법을 이용하는 연구가 많이 이루어져 왔다. 본 논문에서는 외란을 해결하기 위해 적은 힘으로 큰 토크를 발생시킬 수 있는 CMGs (Control Moment Gyros)를 활용하였다. 쿼드로터의 자세 제어를 위해 2개의 CMGs를 활용하였고, 4개의 로터와 2개의 CMGs를 구동하기 위한 시스템을 구성하였다. 구성한 시스템의 제어 성능을 확인하기 위해 외란이 있는 환경에서 자세 제어에 대한 시뮬레이션을 진행하였다.

• 한국표면공학회지
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• 제54권2호
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• pp.90-95
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• 2021

Surface modification technique enabling the control of condensation provides various benefit in various engineering systems, such as heat transfer, desalination, power plants, and so on. In this study, lubricant oil-impregnation into Teflon-coated nanoporous anodic oxide layer of aluminum to enhance a de-wetting and mobility of water droplet on surface. Due to the surface treatment improving water-repellency, the condensation mode is changed to dropwise, thus the frequency of sliding condensed water droplet on surface is increased. For these reasons, the surface of oil-impregnated Teflon-coated nanoporous anodic aluminum oxide shows significantly enhanced condensation heat transfer compared to bare aluminum surface. In addition, the porosity of anodic aluminum oxide affected the mobility of water droplet even with oil-impregnation and Teflon-coating, indicating that the optimization of porous structure of anodic oxide is required for maximizing the condensation heat transfer.

• 드라이브 ㆍ 컨트롤
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• 제16권2호
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• pp.80-90
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• 2019

Fuel cell hybrid electric vehicle is an attractive solution to reduce pollutants, such as noise and carbon dioxide emission. This study presents an approach for energy management and control algorithm based on energetic macroscopic representation for a fuel cell hybrid electric vehicle that is powered by proton exchange membrane fuel cell, battery and supercapacitor. First, the detailed model of the fuel cell hybrid electric vehicle, including fuel cell, battery, supercapacitor, DC-DC converters and powertrain system, are built on the energetic macroscopic representation. Next, the power management strategy was applied to manage the energy among the three power sources. Moreover, the control scheme that was based on back-stepping sliding mode control and inversed-model control techniques were deduced. Simulation tests that used a worldwide harmonized light vehicle test procedure standard driving cycle showed the effectiveness of the proposed control method.