• Journal of Power System Engineering
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• v.21 no.4
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• pp.42-50
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• 2017

A velocity controller using a modified model reference adaptive controller (M-MRAC) and a projection operator for a fish sorting belt conveyor system with uncertainty parameters, input saturation and bounded disturbances is proposed in this paper. To improve the tracking performance and robustness of the proposed controller in the presence of bounded disturbances, the followings are done. Firstly, the reference model for the conventional model reference adaptive controller (CMRAC) is replaced by a modified reference model for a M-MRAC to reduce unexpected high frequency oscillation in control input signal when the adaptation rate is increased. Secondly, estimated parameters in an adaptive law are varied smoothly under bounded external disturbances and a projection operator is utilized in an adaptive law for the proposed M-MRAC controller to be robust. Thirdly, an auxiliary error vector is introduced for compensating the error dynamics of the system when the saturation input occurs. Finally, the experimental results are shown to verify the better effectiveness and performance of the proposed controller under the bounded disturbance and saturated input than that of a CMRAC.

• The Korean Journal of Applied Statistics
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• v.26 no.1
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• pp.131-139
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• 2013

Support vector machines(SVM) may perform poorly in the presence of noise variables; in addition, it is difficult to identify the importance of each variable in the resulting classifier. A feature selection can improve the interpretability and the accuracy of SVM. Most existing studies concern feature selection in the linear SVM through penalty functions yielding sparse solutions. Note that one usually adopts nonlinear kernels for the accuracy of classification in practice. Hence feature selection is still desirable for nonlinear SVMs. In this paper, we compare the performances of nonlinear feature selection methods such as component selection and smoothing operator(COSSO) and kernel iterative feature extraction(KNIFE) on simulated and real data sets.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.231-234
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• 2001

In this paper, we present a robust watermarking technique based on a DCT-domain watermarking approach and an order statistic(OS) filter. The proposed technique inserts one watermark into each of four coefficients within a 2 ${\times}$ 2 block which is scanned on DCT coefficients in the zig-zag ordering from the medium frequency range. The detection algorithm uses an adaptive trimmed mean operator as a local estimator of the embedded watermark to obtain the desired robustness in the presence of additive Gaussian noise and JPEG compression attacks. The performance is analyzed through statistical analysis and numerical experiments. It is shown that the robustness properties against additive noise and JPEG compression attacks are more enhanced than the previous techniques.

• Journal of the Korean Magnetic Resonance Society
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• v.16 no.1
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• pp.11-21
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• 2012

The line-width of carbon nanotubes (CNTs) was studied as a function of the temperature at a frequency of 9.49 GHz in the presence of external electromagnetic radiation. The relative frequency dependence of the absorption power is obtained with the projection operator technique (POT) proposed by Kawabata. The line-width increased as the temperature increased in the high-temperature region (T>200 K). The scattering is little affected in the low-temperature region (T<200 K) because there is no correlation between the resonance field and the Fermi-Dirac distribution function. Thus, the present technique is considered to be more convenient to explain the resonant system as in the case of other optical transition problems.

• Journal of Magnetics
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• v.17 no.1
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• pp.13-18
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• 2012

Starting with Kubo's formula and using the projection operator technique introduced by Kawabata, EPR lineprofile function for a $Mn^{2+}$-doped wurtzite structure GaN semiconductor was derived as a function of temperature at a frequency of 9.49 GHz (X-band) in the presence of external electromagnetic field. The line-width is barely affected in the low-temperature region because there is no correlation between the resonance fields and the distribution function. At higher temperature the line-width increases with increasing temperature due to the interaction of electrons with acoustic phonons. Thus, the present technique is considered to be more convenient to explain the resonant system as in the case of other optical transition systems.

• Journal of the Korean Mathematical Society
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• v.51 no.4
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• pp.679-702
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• 2014

Investigation of the numerical solution of singularly perturbed turning point problems dates back to late 1970s. However, due to the presence of layers, not many high order schemes could be developed to solve such problems. On the other hand, one could think of applying the convergence acceleration technique to improve the performance of existing numerical methods. However, that itself posed some challenges. To this end, we design and analyze a novel fitted operator finite difference method (FOFDM) to solve this type of problems. Then we develop a fitted mesh finite difference method (FMFDM). Our detailed convergence analysis shows that this FMFDM is robust with respect to the singular perturbation parameter. Then we investigate the effect of Richardson extrapolation on both of these methods. We observe that, the accuracy is improved in both cases whereas the rate of convergence depends on the particular scheme being used.

• Archives of Plastic Surgery
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• v.50 no.1
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• pp.96-100
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• 2023

The microsurgical anastomosis is integral to the success of autologous-free tissue transfer. Successful performance of this procedure relies strongly on operator dexterity, which can be made more challenging when blood and edematous fluids obscure the field of view. Workflow is impeded by intermittent irrigation and suctioning, necessitating presence of an assistant, with risk of arterial thrombosis, from vessels being drawn into suction drains. To negate these current disadvantages and minimize the barrier of entry to microvascular operations, we designed, manufactured, and patented a novel three-dimensional printed microsurgical background device with microfluidic capabilities that allow continuous suction and irrigation as well as provide platforms that enable multiangle retraction to facilitate operator autonomy. This was validated in an ex vivo model, with the device found to be superior to the current standard. We believe that this will have major applicability to the improvement of microsurgeon

• Journal of the Korean Mathematical Society
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• v.38 no.2
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• pp.193-226
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• 2001

We study Feynman's Operational Calculus for operator-valued functions of time and for measures which are not necessarily probability measures; we also permit the presence of certain unbounded operators. further, we relate the disentangling map defined within the solutions of evolution equations and, finally, remark on the application of stability results to the present paper.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.8
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• pp.1255-1258
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• 2022

Recently, immersive VR/AR contents have actively increased, and various services related to VR/AR allow users to experience remote places. For example, if failure situations occur frequently in factory of the remote site, mixed reality (MR) with a synthetic virtual human expert in reconstructed remote location can help immediate maintenance task with interaction between the operator and the virtual expert. In this paper, we present a technique for synthesizing the virtual human after capturing a 360-degree panorama of a remote environment, and analyze the effects to apply a method of guiding virtual human by interaction types. According to this paper, it was shown that co-presence level significantly increased when verbal, facial expression, and non-verbal animation of the virtual human was all expressed.

• Journal of the Korean Magnetics Society
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• v.22 no.3
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• pp.73-78
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• 2012

We calculated the electron spin resonance (ESR) line-profile function. The line-width of single-walled carbon nanotube (SWNT) was studied as a function of the temperature at a frequency of 9.5 GHz in the presence of external electromagnetic radiation. The temperature dependence of the line-widths is obtained with the projection operator method (POM) proposed by Argyres and Sigel. The scattering is little affected in the low-temperature region (T < 200 K). We conclude that the calculation process presented in this method is useful for optical transitions in SWNT.