• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.5C
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• pp.486-495
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• 2002

In this paper, we propose a delay reduction method for frame-based packet transmit scheduling algorithm. A high-speed network such as ATM network has to provide some performance guarantees such as bandwidth and delay bound. Framing strategy naturally guarantees bandwidth and enables simple rate-control while having the inherently bad delay characteristics. The proposed delay reduction method uses the same hierarchical frame structure as HRR (Hierarchical Round-Robin) but does not use the static priority scheme such as round-robin. Instead, we use a dynamic priority change scheme so that the delay unfairness between wide bandwidth connection and narrow bandwidth connection can be eliminated. That is, we use FIFO (First-In First-Out) concept to effectively reduce the occurrence of worst-case delay and to enhance delay distribution. We compare the performance for the proposed algorithm with that of HRR. The analytic and simulation results show that HFIFO inherits almost all merits of HRR with fairly better delay characteristics.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.52-55
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• 2001

This paper is to see the availability of electrical signatures as a means for evaluating the performance and monitoring mechanical anomalies of (MOVs). To estimate motor torque, two methods such as d-q frame conversion and air-gap method are suggested and estimated results are compared with measured values. The error between measured and estimated torques is within acceptable error bound with below $1\%$ under varied load. Frequency domain analysis of calculated torque has been done as well. It is shown that monitoring of peak frequency could give useful clues to detect anomalies of MOV. As results, electrical signatures at MOV motor is expected to be an available tool for estimation of motor capacity and monitoring of electrical and mechanical abnormalities.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.5
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• pp.806-811
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• 2017

This paper considers the delay-dependent stability of linear systems with a time-varying delay in the frame work of Lyapunov-Krasovskii functional(LKF) approach. In this approach, an integral inequality is essential to estimate the upper bound of time-derivative of LKF, and a less conservative one is needed to get a less conservative stability result. In this paper, based on free weighting matrices, an improved integral inequality encompassing well-known results is proposed and then a stability result in the form of linear matrix inequality is derived based on an augmented LKF. Finally, two well-known numerical examples are given to demonstrate the usefulness of the proposed result.

• Journal of electromagnetic engineering and science
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• v.17 no.4
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• pp.228-232
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• 2017

The radiation properties and fabrication precautions of a 3D printed, electrically small folded spherical meander wire monopole antenna are investigated. The antenna is self-resonant and shows sufficiently high radiation efficiency at an electrical size ka of 0.4, with the radiation quality factor Q approaching the lower physical bound. In antenna fabrication, the possible structural deformation due to gravity is examined before the antenna frame is 3D-printed. The required conductivity is achieved by multiple manual paintings of a silver paste. The radiation efficiency and pattern show very good agreement with the computed expectations, whereas the resonant frequency deviates by 11.8%. The method to minimize such a fabrication error when using 3D printing technology for wire antennas is discussed.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.739-742
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• 2002

This paper is to see the availability of electrical signatures as a means for evaluating performance of MOVs which are extensively used in safety-related systems in nuclear plants. To estimate motor torque, two methods such as d-q frame conversion and air-gap method are suggested and estimated results are compared with measured values. The error between measured and estimated torques is within acceptable error bound with below $1\%$ under varied load. Frequency domain analysis of calculated torque has been done as well. It is shown that monitoring of peak frequency could give useful clues to detect anomalies of MOV.

• International Journal of Reliability and Applications
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• v.13 no.2
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• pp.71-80
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• 2012

This paper introduces a new approach for evaluating reliability of a complex system in terms of distributional parameters where analytical determination of reliability is intractable. The concept of discrete approximation, reported in the literature so far, fails to meet the latter requirement in terms of distributional parameters. The current work aims at offering a bound based approach where reliability planners not only get a clear idea about the extent of error but also can manipulate in terms of distributional parameters. This reliability approximation has been under taken under the Weibull frame work which is the most widely used model for reliability analysis. Numerical study has been carried out to examine the strength of our proposed reliability approximation via closeness between the two reliability bounds. This approach will be very useful during the early stages of product design as the distributional parameters can be adjusted.

• Korean Journal of Audiology
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• v.23 no.4
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• pp.210-213
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• 2019

The auricle is a three-dimensional cartilaginous frame covered with thin overlying skin. Due to its complex features, reconstructing helical rim defects after the excision of an auricular mass is challenging. Shortage of subcutaneous tissue and the presence of a tightly bound epithelium further hamper the primary closure of lateral (anterior) auricular skin defects. We present herein a case in which we used a helical rim advancement flap along with an additional postauricular skin flap. We achieved a satisfactory esthetic result with minimal loss of helical diameter and a low risk of flap necrosis by preserving the vascular network of the flap. This technique is less traumatic and will facilitate faster healing as well as improved patient recovery.

• Communications of the Korean Mathematical Society
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• v.38 no.3
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• pp.787-805
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• 2023

Let (Ω, µ) be a measure space and {τ_α}_α∈Ω be a normalized continuous Bessel family for a finite dimensional Hilbert space 𝓗 of dimension d. If the diagonal ∆ := {(α, α) : α ∈ Ω} is measurable in the measure space Ω × Ω, then we show that $$\sup\limits_{{\alpha},{\beta}{\in}{\Omega},{\alpha}{\neq}{\beta}}\,{\mid}{\langle}{\tau}_{\alpha},\,{\tau}_{\beta}{\rangle}{\mid}^{2m}\,{\geq}\,{\frac{1}{({\mu}{\times}{\mu})(({\Omega}{\times}{\Omega}{\backslash}{\Delta})}\;\[\frac{{\mu}({\Omega})^2}{\({d+m-1 \atop m}\)}-({\mu}{\times}{\mu})({\Delta})\],\;{\forall}m{\in}{\mathbb{N}}.$$ This improves 48 years old celebrated result of Welch [41]. We introduce the notions of continuous cross correlation and frame potential of Bessel family and give applications of continuous Welch bounds to these concepts. We also introduce the notion of continuous Grassmannian frames.

• Journal of Audiology & Otology
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• v.23 no.4
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• pp.210-213
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• 2019

The auricle is a three-dimensional cartilaginous frame covered with thin overlying skin. Due to its complex features, reconstructing helical rim defects after the excision of an auricular mass is challenging. Shortage of subcutaneous tissue and the presence of a tightly bound epithelium further hamper the primary closure of lateral (anterior) auricular skin defects. We present herein a case in which we used a helical rim advancement flap along with an additional postauricular skin flap. We achieved a satisfactory esthetic result with minimal loss of helical diameter and a low risk of flap necrosis by preserving the vascular network of the flap. This technique is less traumatic and will facilitate faster healing as well as improved patient recovery.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.5
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• pp.47-56
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• 2008

This study was performed to evaluate the effect of Response modification factors (R-factor) in 3-, 9- and 20- story steel Moment Resisting Frame (MRF) buildings. Each structure was designed using a R-factor of 8, as tabulated in the 2000 International Building Code provision (IBC 2000) and Korea Building Code (KBC) 2008. In order to evaluate the maximum and minimum performance expected for such structures, an upper bound and lower bound design were adopted for each model. Next, each analytical model was designed using different R-factors (8, 9, 10, 11, 12) and four different structural periods with the original fundamental period. For a detailed case study, a total of 150 analytical models were subjected to 20 ground motions representing a hazard level with a 2% probability of being exceeded in 50 years. In order to evaluate the performance of the structures, static push-over and non-linear time history analysis (NTHA) were performed, and displacement ductility demand was investigated to consider the ductility capacity of the structures. The results show that the dynamic behaviors for the 3- and 9-story buildings are relatively stable and conservative, while the 20-story buildings show a large displacement ductility demand due to dynamic instability factors. (e.g. P-delta effect and high mode effect)