• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.4
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• pp.303-309
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• 2004

Absorptive material arrangement method for effective interior noise control is proposed. Sound field with arbitrary boundary condition is formulated by Kirchhoff-Helmholtz integral equation. A simple example such as a rectangular cavity will present physical meaning between changing boundary condition and control of sound field. The effect of changing boundary condition is expressed in modal admittance. From this formulation. an admittance map is presented. The admittance map is the figure to represent position where absorptive material is attached for effective interior noise control. The admittance map can be assigned to each resonant frequency. There. however, may be common area of those maps. Then, frequency robust arrangement of absorptive material in noise control will be presented.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1702-1707
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• 2003

Absorptive material arrangement method for effective interior noise control is proposed. Sound field with arbitrary boundary condition is formulated by Kirchhoff-Helmholtz integral equation. A simple example such as a rectangular cavity will present physical meaning between changing boundary condition and control of sound field. The effect of changing boundary condition is expressed in modal admittance. From this formulation, an admittance map is presented. The admittance map is the figure to represent position where absorptive material is attached. The admittance map can be assigned to each resonant frequency. There, however, may be common area of those maps. Then, frequency robust arrangement of absorptive material in noise control will be presented.

• Communications of the Korean Mathematical Society
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• v.32 no.4
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• pp.1067-1076
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• 2017

This paper considers the asymptotic behaviors of the processes generated by the classical ergodic tent map that is defined on the unit interval. We develop a sequential empirical process and get the uniform version of law of iterated logarithm for the tent map by using the bracketing entropy method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.3
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• pp.581-586
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• 2017

The well-known Integral Pulse Frequency Modulation (IPFM) cardiac oscillator has been used to generate the heart beat fluctuations as a representation of the modulatory autonomic nervous activity in terms of sympathetic and parasympathetic state. The IPFM model produces heartbeats by integrating the modulated sinusoid signals and applying the threshold of unity or chaotic threshold levels. This study aims at evaluating the performance of IPFM model by analyzing the influence of the threshold level with comparatively applying preset threshold of unity and Logistic-map and Henon-map chaotic-threshold. Based on our simulated results with interpreting the spectral features of Heart Rate Variability (HRV), we can conclude that the IPFM model with preset threshold level of unity can generate the optimal heartbeat variations int the sense of clinically valid heartbeats.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.186-189
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• 2005

In a clinical setting, developing a reliable method for the automated drug infusion system would improve a drug therapy under the unexpected and acute changes of hemodynamics. The conventional proportional-integral-derivative (PID) controller might not be able to achieve maximum performance because of the unexpected change of the intra- and inter-patient variability. The fuzzy PID control and the conventional PID control were tested under the unexpected response of mean arterial blood pressure (MAP) to a vasopressor agent during acute hypotension. Compared with the conventional PID control, the fuzzy PID control performed the robust MAP regulation regardless of the unexpected MAP response (average absolute value of the error between target value and actual MAP: 0.98 vs. 2.93 mmHg in twice response of the expected MAP and 2.59 vs. 9.75 mmHg in three-times response of the expected MAP). The result was due to the adaptive change of the proportional gain in PID parameters.

• Journal of Institute of Control, Robotics and Systems
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• v.2 no.4
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• pp.318-323
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• 1996

The speed of SR(Switched Reluctance) motor can be controlled by switching angle. However, since the relation between speed and switching is nonlinear, it is difficult for simple adjustment schemes to achieve the desired performances. In this paper, an error.feedback nonlinear compensator with robustness is proposed for improving the performances of the switching angle controlled SR motor. The proposed controller consists of integral type control and relay type control. The integral type controller which operates regulation, is derived by the steady.state I/O(input/output) map and the relay type controller which works tracking, is designed by Lyapunov stability theory. The validities of the proposed controller are confirmed with the experimental results.

• Journal of applied mathematics & informatics
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• v.28 no.1_2
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• pp.397-409
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• 2010

We prove the existence of common fixed points for multivalued maps satisfying a contractive condition of an integral type. Our results are extent ions of results of Feng and Liu[Y. Feng, S. Liu, Fixed point theorems for multi-valued contractive mappings and multi-valued Caristi type mappings, J. Math. Anal. Appl. 317(2006), 103-112] and also, extent ions of results of Daffer and Kaneko[P. Z. Daffer, H. Kaneko, Fixed points of generalized contractive multi-valued map pings, J. Math. Anal. Appl. 192(1995), 655-666]. A main result in Feng and Liu[Y. Feng, S. Liu, Fixed point theorems for multi-valued contractive mappings and multi-valued Caristi type mappings, J. Math. Anal. Appl. 317(2006), 103-112] is proved under necessary additional conditions.

• Nonlinear Functional Analysis and Applications
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• v.26 no.1
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• pp.83-92
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• 2021

This paper studies approximate solutions for a class of nonlinear diffusion population models. Our methods are to use the fundamental solution of heat equations to construct integral forms of the models and the well-known Banach compression map theorem to prove the existence of positive solutions of integral equations. Non-steady-state local approximate solutions for suitable harvest functions are obtained by utilizing the approximation theorem of multivariate continuous functions.

• Journal of applied mathematics & informatics
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• v.41 no.5
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• pp.937-946
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• 2023

In this present work, we inaugurated subclasses of analytic functions which are associated with generalized Mittag Leffler Functions. Inclusion implications and integral preserving properties under the Bernardi integral operator are investigated. Some consequences of these findings are also illustrated.

• The Korean Journal of Nuclear Medicine Technology
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• v.19 no.2
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• pp.87-92
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• 2015

Purpose When the patients takes myocardial perfusion SPECT using $^{201}Tl$, the operator gives the patients an injection of $^{201}Tl$. But the uniformity correction map in SPECT uses $^{99m}Tc$ uniformity correction map. Thus, we want to compare the image quality when it uses $^{99m}Tc$ uniformity correction map and when it uses $^{201}Tl$ uniformity correction map. Materials and Methods Phantom study is performed. We take the data by Asan medical center daily QC condition with flood phantom including $^{201}Tl$ 21.3 kBq/mL. After postprocessing with this data, we analyze CFOV integral uniformity(I.U) and differential uniformity(D.U). And we take the data with Jaszczak ECT Phantom by American college of radiology accreditation program instruction including $^{201}Tl$ 33.4 kBq/mL. After post processing with this data, we analyze spatial Resolution, Integral Uniformity(I.U), coefficient of variation(C.V) and Contrast with Interactive data language program. Results In the flood phantom test, when it uses $^{99m}Tc$ uniformity correction map, Flood I.U is 3.6% and D.U is 3.0%. When it uses $^{201}Tl$ uniformity correction map, Flood I.U is 3.8% and D.U is 2.1%. The flood I.U is worsen about 5%, but the D.U is improved about 30% inversely. In the Jaszczak ECT phantom test, when it uses $^{99m}Tc$ uniformity correction map, SPECT I.U, C.V and contrast is 13.99%, 4.89% and 0.69. When it uses $^{201}Tl$ uniformity correction map, SPECT I.U, C.V and contrast is 11.37%, 4.79% and 0.78. All of data are improved about 18%, 2%, 13% The spatial resolution was no significant changes. Conclusion In the flood phantom test, Flood I.U is worsen but Flood D.U is improved. Therefore, it's uncertain that an image quality is improved with flood phantom test. On the other hand, SPECT I.U, C.V, Contrast are improved about 18%, 2%, 13% in the Jaszczak ECT phantom test. This study has limitations that we can't take all variables into account and study with two phantoms. We need think about things that it has a good effect when doctors decipher the nuclear medicine image and it's possible to improve the image quality using the uniformity correction map of other radionuclides other than $^{99m}Tc$, $^{201}Tl$ when we make other nuclear medicine examinations.