• Journal of the Korean Mathematical Society
• /
• v.49 no.4
• /
• pp.715-731
• /
• 2012

This paper considers the stability of positive steady-state solutions bifurcating from the trivial solution in a delayed Lotka-Volterra two-species predator-prey diffusion system with a discrete delay and subject to the homogeneous Dirichlet boundary conditions on a general bounded open spatial domain with smooth boundary. The existence, uniqueness and asymptotic expressions of small positive steady-sate solutions bifurcating from the trivial solution are given by using the implicit function theorem. By regarding the time delay as the bifurcation parameter and analyzing in detail the eigenvalue problems of system at the positive steady-state solutions, the asymptotic stability of bifurcating steady-state solutions is studied. It is demonstrated that the bifurcating steady-state solutions are asymptotically stable when the delay is less than a certain critical value and is unstable when the delay is greater than this critical value and the system under consideration can undergo a Hopf bifurcation at the bifurcating steady-state solutions when the delay crosses through a sequence of critical values.

• 제어로봇시스템학회:학술대회논문집
• /
• 1991.10b
• /
• pp.1888-1893
• /
• 1991

Systematic design of a controller for a water temperature system was considered, with the intention of devising an accurate control experiment. The results of an experiment using a water temperature system based on the pole placement regulator showed water temperature oscillation and steady state error. This paper proposed a. method for eliminating both the oscillation and the steady state error. The oscillation was eliminated by a drive delay compensation technique, in which a future state value of the system was predicted through a real time computer simulation. The steady state error was eliminated by an steady state error correction technique, in which an actual steady state heatrate in the system model was replaced by an imaginary heatrate. By combining these two techniques, we obtained an experimental result for water temperature control of 0.01 (.deg. C) accuracy. Furthermore, the proposed method was evaluated relatively by comparing the experimental results using several other methods and proved to be the most accurate and convenient control method for the delay system.

• Speech Sciences
• /
• v.11 no.4
• /
• pp.143-150
• /
• 2004

This study was done to compare thresholds between those of Auditory Brainstem Response (ABR) with clicks or tonebursts and Multiple Auditory Steady-State Response (MASTER). The results would give a promising tool for evaluating frequency-specific hearing sensitivity in infants or young children. The correlation coefficient value between the click ABR thresholds and MASTER thresholds at carrier frequencies, 500, 1,000, 2,000 Hz, and 4,000 Hz was obtained at Pearson 0.91, 0.94, 0.93, and 0.91.

• Journal of Institute of Control, Robotics and Systems
• /
• v.17 no.9
• /
• pp.897-901
• /
• 2011

This paper presents a TS (Takagi-Sugeno) type FLC (Fuzzy Logic Controller) with only 3 rules. The choice of parameters of FLC is very difficult job on design FLC controller. Therefore, the choice of appropriate linguistic variable is an important part of the design of fuzzy controller. However, since fuzzy controller is nonlinear, it is difficult to analyze mathematically the affection of the linguistic variable. So this choice is depend on the expert's experience and trial and error method. In the design of the system, we use a variety of response characteristics like stability, rising time, overshoot, settling time, steady-state error. In particular, it is important for a stable system design to predict the steady-state error because the system's steady-state response of the system is related to the overall quality. In this paper, we propose the method to choose the consequence linear equation's parameter of T-S type FLC in the view of steady-state error. The parameters of consequence linear equations of FLC are tuned according to the system error that is the input of FLC. The full equation of T-S type FLC is presented and using this equation, the relation between output and parameters can represented. As well as the FLC parameters of consequence linear equations affect the stability of the system, it also affects the steady-state error. In this study, The system according to the parameter of consequence linear equations of FLC predict the steady-state error and the method to remove the system's steady-state error is proposed using the prediction error value. The simulation is carried out to determine the usefulness of the proposed method.

• Korean Journal of Veterinary Research
• /
• v.15 no.2
• /
• pp.187-198
• /
• 1975

Although considerable research has been done on the blood chemistry of domestic animals, little work has been made of the changes associated with age. Moreover, the records about physiology of the goat were not much available in Korea, and a comprehensive survey of the blood values of the Korean native goat has not been made. The object of the present investigation was to make good this deficiency and to suggest standards for the blood chemical values of Korean native goats from birth to maturity. The goats were kept under average farming conditions in Korea. Blood samples were collected from the jugular vein at birth, at one and four days, at one, two, three and four weeks, and at two, three, six, nine and twelve months of age. The results obtained in this work were summarized as follows: 1. The highest concentration of serum glucose was observed at birth and it decreased gradually until three months of age, showing a steady state thereafter. 2. The concentration of total serum protein was a little higher at one day of age than at birth and showed a steady state until seven days of age; then it decreased slightly at two weeks of age and recovered at three weeks of age and showed a steady state until twelve months of age. The concentration of serum albumin was increased a little at one day of age and revealed a steady state thereafter. The concentration of serum globulin showed three phases - a fall during the first two weeks to reach minimum, a rise to the fourth week, and a fall at two months of age, showing a steady state thereafter. The lowest value of albumin fraction was observed at birth, then the value increased gradually until three months of age and revealed a stealer state thereafter. The highest value of globulin fraction was observed at birth, then the gradual decrease of the value was seen until three months of age; thereafter the value showed a steady state. 3. Albumin/globulin ratio was the minimum at birth, then it increased to reach a maximum at two weeks of age and decreased a little thereafter. 4. The concentration of total serum cholesterol showed a gradual increase during the first three months and fell to reach adult revel at six months of age. 5. Urea nitrogen in serum decreased during the first week to reach a minimum, then it increased at three months of age, and showed a fell to mature level at six mouths of age. 6. The concentration of serum creatinine was not affected by age. 7. The concentration of total serum calcium was a little higher during the first two weeks than the other period during the first year of life. 8. The concentration of serum inorganic phosphorus showed a gradual rise to reach a maximum and a gradual fall to reach adult level at nine months of age. 9. No significant sex differences of serum chemical values were recognized.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.7 no.1
• /
• pp.11-18
• /
• 1983

For the steady-state solutions of vibratory systems where the dynamics involves nonlinearity and discontinuity, a method of numerical simulation has been normally used. This paper presents a new approach which may overcome some difficulties in the simulation method. This approach is based on the fundamental assumption that the steady-state forced vibration is periodic, so that the problem is formulated as a two-point boundary-value problem and can be solved by Waner's algorithm. This method is demonstrated through the solutions of a linear system, a system with Coulomb friction and an impact pair. It is found that the method gives true solutions well both for linear and nonlinear systems, which convinces us of the usefulness of the method.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.17 no.3
• /
• pp.205-212
• /
• 2012

This paper proposes the fuzzy logic based variable step-size MPPT (Maximum Power Point Tracking) method for the stability at the steady state and the improvement of the transient response in the wind power system. If the change value of duty ratio is set on stability of the steady state, MPPT control traces to maximum power point slowly. And if the change value is set on improvement of the transient response, the system output oscillates at the maximum power point. By adjusting the step size with fuzzy logic, it can be improved the MPPT response speed and stability at steady state when MPPT control is performed to track the maximum power point. The effectiveness of the proposed method has been verified by simulations and experimental results.

• Management Science and Financial Engineering
• /
• v.16 no.1
• /
• pp.119-135
• /
• 2010

In this paper, we readdress the optimization problem for minimizing the inspection cost in a back-light unit inspection system, which forms a network including a K-stage inspection system, a source inspection shop, and a re-inspection shop. In order to formulate our objective function when the system is in a steady state, assuming that the number of nonconforming items in a lot follows a binomial distribution when a lot is formed for inspection, we make a steady-state network flow analysis between shops, and derive the steady-state amount of flows between nodes and the steady-state fraction defectives by solving a nonlinear balance equation. Finally we provide some fundamental properties and an enumeration method for determining an optimal value of K which minimizes our objective function. In addition, we compare our results numerically with previous ones.

• The Journal of the Acoustical Society of Korea
• /
• v.10 no.3
• /
• pp.44-50
• /
• 1991

To recognize continued speech, it is necessary to segment the connected acoustic signal into phonetic units. In this paper, as a parameter to detect the transition regions in continued speech, we propose a new noramlized AMDF. The suggested parameter represents a change rate of magnitude of speech signals. As comparing this value with the adjactent frames value the state of the frames can be distinguished as a level between the steady state and transient state.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.8 no.1
• /
• pp.18-23
• /
• 2009

This study analyzes the thermal stress at automotive radiators on steady and transient states. The maximum displacement is shown at the lower corner of upper tank with the value of 0.51mm. The displacement becomes smaller at the center of radiator and it becomes larger at this edge. The maximum thermal stress with the value of 62 MPa is shown at the contact between upper tank and cooling plate. Thermal maximum stress with the transient state at the elapsed time of 10 second is lower than that at steady state as much as 0.7%.