• Transactions of the Korean Society of Automotive Engineers
• /
• v.6 no.4
• /
• pp.1-8
• /
• 1998

In order to solve the conflict problem between the ride comfort and the road holding, the optimal design of shock absorber that minimizes the r.m.s. of sprung mass vertical acceleration and pitch rate with the understeer characteristics constraints in the high speed stability is proposed. The design of experiments and the nonlinear optimization algorithm are used together to obtain the optimal design of shock absorber. The second order regression models of the input variables(front and rear damping coefficients) and the output variables (ride comfort index and road holding one) are obtained by the central composite design in the design of experiments. Then the optimal design of shock absorber can be systematically adjusted with applying the nonlinear optimization algorithm to the obtained second order regression model. The frequency response analysis of sprung mass acceleration and pitch rate shows the effectiveness of the proposed optimal design of shock absorber in the sprung mass resonance range with the understeer characteristics constraints.

• Journal of Institute of Control, Robotics and Systems
• /
• v.14 no.3
• /
• pp.295-300
• /
• 2008

In this paper, a new looper controller is proposed to minimize the tension variation of a strip in the hot strip finishing mill. The proposed control technology is based on a receding horizon control (RHC) to satisfy the constraints on the control input/state variables. The finite terminal weighting matrix is used instead of the terminal equality constraint. The closed loop stability of the RHC for the looper system is analyzed to guarantee the monotonicity of the optimal cost. Furthermore, the RHC is combined with a 4SID(Subspace-based State Space System Identification) model identifier to improve the robustness for the parameter variation and the disturbance of an actuator. As a result, it is shown through a computer simulation that the proposed control scheme satisfies the given constraints on the control inputs and states: roll speed, looper current, unit tension, and looper angle. The control scheme also diminishes the tension variation for the parameter variation and the disturbance as well.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.52 no.1
• /
• pp.31-37
• /
• 2003

A robust tracking control for nonholonomic dynamic systems is proposed in this paper. Since nonholonomic dynamic systems have constraints imposed on motions that are not integrable, i.e., the constraints cannot be written as time derivatives of some functions of generalized coordinates, advanced techniques are needed for their control. It is shown that if the state of nonholonomic systems is mapped into a bounded space by a coordinate transformation, a robust controller for dynamic models of nonholonomic systems with input disturbances can be designed using sliding mode control. Stability and robustness of the proposed controller are proved in the Lyapunov sense. Numerical simulations on the trajectory tracking of a two-wheeled mobile robot are conducted to validate the effectiveness of the proposed controller.

• Journal of the Korea Society of Computer and Information
• /
• v.23 no.4
• /
• pp.107-114
• /
• 2018

Recently, various wearable personal devices such as a smart watch have been developed and these personal devices are being miniaturized. The user desires to receive new services from personal devices as well as services that have been received from personal computers, anytime and anywhere. However, miniaturization of devices involves constraints on resources such as limited input and output and insufficient power. In order to solve these resource constraints, this paper proposes a resource collaboration system which provides a service by composing sharable resources in the resource sharing environment like IoT. the paper also propose a method to infer and recommend user-customized resources among various sharable resources. For this purpose, the paper defines an ontology for resource inference. This paper also classifies users behavior types based on a user model and then uses them for resource recommendation. The paper implements the proposed method as a prototype system on a personal device with limited resources developed for resource collaboration and shows the effectiveness of the proposed method by evaluating user satisfaction.

• Journal of Institute of Control, Robotics and Systems
• /
• v.20 no.2
• /
• pp.163-169
• /
• 2014

Using the classical cascade voltage control strategy, this paper proposes an analytical solution to an MPC (Model Predictive Control) problem with a hexagonal input constraint set for the inner-loop to regulate the output voltage of the UPS (Uninterruptible Power Supply). Focus is placed on how to deal with the hexagonal input constraint set without any approximation. Following the conventional cascade voltage control strategy, the PI (Proportional-Integral) controller is used in the outer-loop in order to regulate the output voltage. The simulation results illustrate that the capacitor voltage rapidly goes to its reference in a satisfactory manner while keeping other state variables bounded under an unexpected load changes.

• Journal of environmental and Sanitary engineering
• /
• v.15 no.3
• /
• pp.31-36
• /
• 2000

Conventional membrane systems was difficults to treatment for the swine waste water. Technological advances in membrane filtration systems have created opportunity for the swine wastewater to treat effluent streams in order to meet stricter environmental constraints. "Vibratory Shear Enhanced Processing(VSEP)" developed by new logic international makes it possible to filter effluent streams without the fouling problem exhibited by conventional membrane systems. Various kinds of waste water occurred to and swine wastewater experiment with "VSEP" set up conventional reverse osmosis membrane (ACM-4, ESPA, BW-30). The results were as followes : Treatment efficiency for the input COD(From $332mg/{\ell}$ to $4,968mg/{\ell}$) was 98%. Treatment efficiency for the input SS(From $140mg/{\ell}$ to $4,040mg/{\ell}$) was 100%(All together). Treatment efficiency for the input T-N(From $155mg/{\ell}$ to $934mg/{\ell}$) was 97%~99.8%. Treatment efficiency for the input T-P(From $28.6mg/{\ell}$ to $132mg/{\ell}$) was 99.7% and up. ESPA membrane excels three types of reverse osmosis membranes applied VSEP in removal efficiency.

• International Journal of Control, Automation, and Systems
• /
• v.6 no.3
• /
• pp.327-338
• /
• 2008

A fault tolerant control system design technique has been proposed and analyzed for managing performance degradation in the presence of multiple faults in actuators. The method is based on a control structure with a model reference reconfigurable control design in an inner loop and command input adjustment in an outer loop. The reduced dynamic performance requirements in the presence of different actuator faults are accounted for through different performance reduced (degraded) reference models. The degraded steady-state performances are governed by the reduced levels of command input. The reconfigurable controller is designed on-line automatically in an explicit model reference control framework so that the dynamics of the closed-loop system follow that of the performance reduced reference model under each fault condition. The reduced command input level is determined to prevent potential actuator saturation. The proposed method has been evaluated and analyzed using an aircraft example against actuator faults subject to constraints on the magnitude and slew-rate of actuators.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.7
• /
• pp.1270-1276
• /
• 2016

This paper proposes the controller design for regulation control of two-link robot arm using sum of squares (SOS) control method that takes into account the input constraint. The existing studies of two link robotic arm system used a linear model of all the non-linearity of the system is linearized. For a linear controller, since the model of the system is simplified, it is possible to design a controller in consideration of constraints on the disturbance. However, there is a limit to the performance using a linearized model for a system with a complex nonlinear properties. To compensate for this in the case of using a fuzzy LMI method, it is necessary to have a large number of linear models and thus there is a disadvantage that the system becomes complicated. To solve these problems, we represents a two-link robot arm system with a polynomial model using a Taylor series expansion and design the controller considering the case where the magnitude of the control input is limited using SOS method. We demonstrate by simulations the feasibility of the proposed algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.9
• /
• pp.1010-1019
• /
• 2016

The K-user multiple-input single-output broadcast channel is considered under per-antenna power constraints, i. e., each transmit antenna must satisfy its own power constraints. A low complexity zeroforcing(ZF) precoder is proposed when the number of transmit antennas M is greater than K. The proposed precoder design significantly reduces computational complexity for the precoder construction while attaining the sum spectral efficiency close to that achievable by the optimal ZF precoder.

• Asian-Australasian Journal of Animal Sciences
• /
• v.32 no.8_spc
• /
• pp.1266-1274
• /
• 2019

This paper presents a review of dairy goat production in sub-Saharan Africa (SSA) from 2010- 2017, its current state, constraints and prospects for research and development. Since the introduction of dairy goats in SSA in pre-colonial times, their populations have continued to increase due to declining land size as a result of land fragmentation and increasing demand for goat milk. The current goat population in SSA is 372,716,040 head of which only 15.98% used for milk production. Populations in the Eastern and Western regions of SSA have shown an increasing trend from 2010 to 2017. The Southern Africa goat population is on the decline at an annual rate of about 1.77% whereas Central Africa has had a constant goat population within the same period. Eastern Africa reported the highest increase in the population of goats used for milk production. Milk production was highest in Eastern Africa and lowest in Southern Africa. However, dairy goat productivity remained constant in the Eastern region throughout the review period. Dairy goats are mainly raised under smallholder mixed crop-livestock systems. To enhance the development of the dairy goat, concerted efforts should be made to alleviate the constraints that stifle its growth. These constraints can be categorized into nutrition and feeding, breeding and reproduction, diseases, parasites, climate change, and underdeveloped dairy goat products market. Effective management of dairy goats requires a holistic approach and there is the need to expand the markets by further sensitization on the nutritional and medicinal advantages of dairy goat products. In order to achieve rapid development in the dairy goat sub sector, research and development initiatives should be directed towards alleviating the hurdles in nutrition and feeding, breeding, animal health and resilience as well as dairy goat markets.