• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.5
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• pp.33-39
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• 2010

In this paper, we propose an improved anti-collision algorithm. We have designed an anti-collision unit using this algorithm for the 18000-6 Type C Class 1 Generation 2 standard (Gen2). The Gen2 standard uses a Q-algorithm for incremental method on the Dynamic Slot-Aloha algorithm. It has basically enhanced performance over the Slot-Aloha algorithm. Unfortunately, there are several non-clarified parts: initial value. If an incorrect value is selected, it causes degradation in performance. To increase throughput and system efficiency, and to decrease tag identification time, we propose an improved anti-collision algorithm. prorosed Q algorithm has an increment of 5% of system efficiency and a decrement of 9% of tag identification time.

• Journal of Microbiology and Biotechnology
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• v.21 no.5
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• pp.494-502
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• 2011

Coenzyme $Q_{10}$ ($CoQ_{10}$) is a widely used supplement in heart diseases treatment or antioxidative dietary. The microbial production of $CoQ_{10}$ was enhanced by addition of solanesol and novel precursors recovered from waste tobacco. The novel precursors were separated by silica gel and identified as ${\alpha}$-linolenic acid (LNA) and butylated hydroxytoluene (BHT) based on the effect on $CoQ_{10}$ production and GC-MS. The effects of novel precursors on $CoQ_{10}$ production by Sphingomonas sp. ZUTE03 were further evaluated in a two-phase conversion system. The precursor's combination of solanesol (70 mg/l) with BHT (30 mg/l) showed the best effect on the improvement of $CoQ_{10}$ yield. A maximal $CoQ_{10}$ productivity (9.5 mg $l^{-1}$ $h^{-1}$) was achieved after 8 h conversion, with a molar conversion rate of 92.6% and 92.4% on BHT and solanesol, respectively. The novel precursors, BHT and LNA in crude extracts from waste tobacco leaves, might become potential candidates for application in the industrial production of $CoQ_{10}$ by microbes.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.653-655
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• 2011

EPCglobal proposed a Q-algorithm, which is used for selecting a slot-count in the next query round. However, it is impossible to allocate an optimized slot-count because the original Q-algorithm did not define an optimized weight C value. In this paper, we propose an adaptive Q-algorithm, in which we differentiate the weight values with respect to collision and empty slots. The weight values are defined with the identification time as well as the collision probability.

• ETRI Journal
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• v.38 no.5
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• pp.911-921
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• 2016

This paper presents the description, practical implementation, and stability analysis of a recently proposed, energy-efficient, medium access control protocol for wireless sensor networks, ALOHA-Q, which employs a reinforcement-learning framework as an intelligent transmission strategy. The channel performance is evaluated through a simulation and experiments conducted using a real-world test-bed. The stability of the system against possible changes in the environment and changing channel conditions is studied with a discussion on the resilience level of the system. A Markov model is derived to represent the system behavior and estimate the time in which the system loses its operation. A novel scheme is also proposed to protect the lifetime of the system when the environment and channel conditions do not sufficiently maintain the system operation.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.6
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• pp.372-375
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• 2005

The tracking performance of optical disk drive(ODD) system can be improved using disturbance observer(DOB). But, DOB was not easily applied in the ODD system because the additional microprocessor was needed. In this paper, we propose an error-based modified disturbance observer(EM-DOB) for ODD system. Due to the simplified structure of EM-DOB, the system is easily implemented to the digital control algorithm or the analog circuit. In these algorithms, disturbances rejection performance of system can be tuned as Q filter parameters are selected. Based on analysis of sensitivity function, three guidelines of Q filter design are suggested. Experimental results of DOB and EM-DOB are evaluated under the forced disturbances.

• Journal of Advanced Navigation Technology
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• v.19 no.3
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• pp.244-249
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• 2015

High-altitude electromagnetic pulse (HEMP) is generated from a nuclear burst at high altitudes above the Earth, the electromagnetic fields reach the ground nearly simultaneously with regard to the operation time of systems. The aim of this analysis is to inquire about HEMP characteristics and to analyze about effect in orthogonal frequency division multiplexing (OFDM) system. Specifically, HEMP characteristics are classified field sources, spatial coverage, time domain behavior, frequency spectrum and field intensities in this study. Bits error rate (BER) of the receiver with the software simulation is confirmed for the HEMP effect. Q-factor made a difference about interference duration by transfer characteristics of system. When Q factor is smaller, the recovery time from HEMP interference is short. To the contrary, if the Q factor is larger, the recovery duration is lasted longer by 300-600%.

• Journal of applied mathematics & informatics
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• v.35 no.1_2
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• pp.121-130
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• 2017

This study is concerned with the existence of positive solution for the following nonlinear elliptic system $$\{-M_1(\int_{\Omega}{\mid}x{\mid}^{-ap}{\mid}{\nabla}u{\mid}^pdx)div({\mid}x{\mid}^{-ap}{\mid}{\nabla}u{\mid}^{p-2}{\nabla}u)\\{\hfill{120}}={\mid}x{\mid}^{-(a+1)p+c_1}\({\alpha}_1A_1(x)f(v)+{\beta}_1B_1(x)h(u)\),\;x{\in}{\Omega},\\-M_2(\int_{\Omega}{\mid}x{\mid}^{-bq}{\mid}{\nabla}v{\mid}^qdx)div({\mid}x{\mid}^{-bq}{\mid}{\nabla}v{\mid}^{q-2}{\nabla}v)\\{\hfill{120}}={\mid}x{\mid}^{-(b+1)q+c_2}\({\alpha}_2A_2(x)g(u)+{\beta}_2B_2(x)k(v)\),\;x{\in}{\Omega},\\{u=v=0,\;x{\in}{\partial}{\Omega},$$ where ${\Omega}$ is a bounded smooth domain of ${\mathbb{R}}^N$ with $0{\in}{\Omega}$, 1 < p, q < N, $0{\leq}a$ < $\frac{N-p}{p}$, $0{\leq}b$ < $\frac{N-q}{q}$ and ${\alpha}_i,{\beta}_i,c_i$ are positive parameters. Here $M_i,A_i,B_i,f,g,h,k$ are continuous functions and we discuss the existence of positive solution when they satisfy certain additional conditions. Our approach is based on the sub and super solutions method.

• Journal of Aerospace System Engineering
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• v.16 no.4
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• pp.10-16
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• 2022

Since aviation systems are developed as the complex form of software a hardware, the necessity to apply to relevant guidelines is increasing. It is however uncommon that international development guidelines regarding electronic hardware are applied to current domestic aviation systems. In this paper, we compare and analyze DO-254 and ECSS-Q-ST-60-02C, electronic hardware development guidelines with the case of KASS (Korea Augmentation Satellite System) Performance Suitability, based on the project of SBAS (Satellite Based Augmentation System) development and construction.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.7
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• pp.795-805
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• 2016

Nonlinear normal modes(NNMs) is a branch of periodic solution of nonlinear dynamic systems. Determination of stable periodic solution is very important in many engineering applications since the stable periodic solution can be an attractor of such nonlinear systems. Periodic solutions of nonlinear system are usually calculated by perturbation methods and numerical methods. In this study, numerical method is used in order to calculate the NNMs. Iteration of the solution is presented by multiple shooting method and continuation of solution is presented by pseudo-arclength continuation method. The stability of the NNMs is analyzed using Floquet multipliers, and bifurcation points are calculated using indirect method. Proposed analyses are applied to two nonlinear numerical models. In the first numerical model nonlinear spring-mass system is analyzed. In the second numerical model Jeffcott rotor system which has unstable equilibria is analyzed. Numerical simulation results show that the multiple shooting method can be applied to self excited system as well as the typical nonlinear system with stable equilibria.

• Journal of Korea Water Resources Association
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• v.49 no.12
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• pp.1015-1025
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• 2016

In general, manholes installed as urban drainage facilities are a variety forms such as straight path manholes, 90 degree bend manhole, three-way combining manhole, and four-way combining manhole. In particular, the surcharged flow at a four-way manholes installed in the downstream of urban sewer system is the main cause of the urban inundation caused by the energy loss. Therefore, it is necessary to analyze the flow characteristics and estimate the head loss coefficients at surcharged four-way combining manholes. The hydraulic experimental apparatus which can change the manhole shapes (square, circle) and flow ratios were installed to estimate the head loss coefficients. In the experiments, two inflows ($Q_m$, $Q_{lat}$) were varied from 0 to $4.8{\ell}/sec$ and 24 combinations were tested in total. The flow ratios $Q_{lat}/Q_{out}$ were varied from 0 to 1 for a total flow $Q_{out}$ ($Q_{out}=Q_m+2Q_{lat}$) of 2, 3, 4, and $4.8{\ell}/sec$, respectively. The variation of head losses were strongly influenced by the lateral inflow because the head loss coefficient increases as the flow ratios $Q_{lat}/Q_{out}$ increases. It was estimated head loss coefficients of the circular manhole is slightly lower than those of the square manhole. However, there was no significant difference of head loss as discharges change. The range of head loss coefficients at four-way combining manhole according to the change of the lateral inflow ratio was estimated to be 0.4 to 0.8. Also, the relation equations between the head loss coefficients (K) and the lateral inflow ratios ($Q_{lat}/Q_{out}$) were suggested in this paper.