• 대한화학회지
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• 제52권5호
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• pp.461-467
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• 2008

• ETRI Journal
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• 제29권6호
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• pp.707-715
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• 2007

In-phase/quadrature (I/Q) imbalances, which are generated by non-ideal transceiver components, are inevitable physical phenomena that cause the performance of practical communication systems to be degraded. In this paper, we provide a new closed-form expression for the bit error rate of hierarchical M-ary phase shift keying with I/Q phase and amplitude imbalances and analyze the effect of I/Q imbalances on BER performance over an additive white Gaussian noise channel.

• 대한수학회논문집
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• 제23권2호
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• pp.161-167
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• 2008

A ring R is called an $I_0$-ring if each left ideal not contained in the Jacobson radical J(R) contains a non-zero idempotent. If, in addition, idempotents can be lifted modulo J(R), R is called an I-ring or a potent ring. We study whether these properties are inherited by some related rings. Also, we investigate the structure of potent rings.

• 제어로봇시스템학회논문지
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• 제11권5호
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• pp.423-428
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• 2005

This paper proposes a new edge detection method using a $3{\times}3$ ideal binary pattern and lookup table (LUT) for the mobile robot localization without any parameter adjustments. We take the mean of the pixels within the $3{\times}3$ block as a threshold by which the pixels are divided into two groups. The edge magnitude and orientation are calculated by taking the difference of average intensities of the two groups and by searching directional code in the LUT, respectively. And also the input image is not only partitioned into multiple groups according to their intensity similarities by the histogram, but also the threshold of each group is determined by fuzzy reasoning automatically. Finally, the edges are determined through non-maximum suppression using edge confidence measure and edge linking. Applying this edge detection method to the mobile robot localization using projective invariance of the cross ratio. we demonstrate the robustness of the proposed method to the illumination changes in a corridor environment.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권3호
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• pp.1462-1476
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• 2017

The current literature on discrete-time Markov chain (DTMC) based analysis of IEEE 802.15.6 MAC protocols for wireless body area networks (WBANs), do not consider the ACK timeout state, wherein the colliding nodes check the ill fate of their transmissions, while other contending nodes perform backoff check that slot as usual. In this paper, our DTMC model accurately captures the carrier sense multiple access with collision avoidance (CSMA/CA) mechanism of IEEE 802.15.6 medium access control (MAC) and allows the contending nodes performing backoff to utilize the ACK timeout slot during collisions. The compared rigorous results are obtained by considering a non-ideal channel in non-saturation conditions, and CSMA/CA parameters pertaining to UWB PHY of IEEE 802.15.6 MAC protocols.

• Journal of Electrical Engineering and Technology
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• 제9권2호
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• pp.423-432
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• 2014

Non-dominated Sorting Genetic Algorithm-II (NSGA-II) is applied for solving Combined Economic Emission Dispatch (CEED) problem with valve-point loading of thermal generators. This CEED problem with valve-point loading is a nonlinear, constrained multi-objective optimization problem, with power balance and generator capacity constraints. The valve-point loading introduce ripples in the input-output characteristics of generating units and make the CEED problem as a nonsmooth optimization problem. To validate its effectiveness of NSGA-II, two benchmark test systems, IEEE 30-bus and IEEE 118-bus systems are considered. To compare the Pareto-front obtained using NSGA-II, reference Pareto-front is generated using multiple runs of Real Coded Genetic Algorithm (RCGA) with weighted sum of objectives. Comparison with other optimization techniques showed the superiority of the NSGA-II approach and confirmed its potential for solving the CEED problem. Numerical results show that NSGA-II algorithm can provide Pareto-front in a single run with good diversity and convergence. An approach based on Technique for Ordering Preferences by Similarity to Ideal Solution (TOPSIS) is applied on non-dominated solutions obtained to determine Best Compromise Solution (BCS).

• 제어로봇시스템학회논문지
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• 제2권1호
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• pp.5-8
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• 1996

This paper proposea a new adaptive algorithm to improve the performance fo a robust adaptive control system. This adaptive algorithm counteracts the effects of disturbances and makes the time derivative of Lyapunov function non-positive, $V{\leq}0$. As a result, the output error approaches zero as $t\;\rightarrow\;\infty$ not only in the presence of bounded disturbances, but also in the ideal case. The effectiveness of this proposed algorithm is demonstrated by the stability analysis and simulation results.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.263-263
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• 2000

Electromagnetic Suspension(EMS) System produces no noise, friction and heat through non-contacting operation Therefore, the applicable device using EMS system has a lot of attraction in case of the high-speed and non-contacting transmission EMS with nonlinear properties requires a precise airgap position control and stable kinematics characteristics under the disturbances, In this study, the nonlinear system was linearized by a Nonlinear Feedback Lineariztion(NFL) method. The NFL method requires that the modelling should be exact, and the state variables should be measured and a rapidly operating controller be necessary on account of a heavy data calculating In the experiments. the ideal control characteristics of the NFL was acquired through simulation at first. then the characteristics of the actual system were compared with those of simulation. In addition, the results by NFL were examined and analysed considering the characteristics of the PID control. The Control by NFL shows much stable control characteristics than the PID control. Whereas, the steady state errors occur for various disturbances. hence a robust control design is remained for a further study.

• 한국산학기술학회논문지
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• 제11권5호
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• pp.1768-1772
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• 2010

분자내부 회합은 계면활성제계, 특히 콜로이드와 생체물질에 있어서 수소결합 중에서 매우 중요한 역할을 나타낸다. 미셀과 마이크로에멀젼을 형성하는 양친매성 계는 분자간 회합뿐만 아니라 분자내부 회합 때문에 매우 비이상적인 거동을 나타낸다. 본 연구의 목적은 계면활성제를 함유한 혼합물의 상거동을 계산하기 위하여, 내외부 분자 회합을 설명할 수 있는 수정된 베이츠만 통계역학이론과 결합된 유사화학반응 비무질도서 격자모델을 제시하는 것이다. 본 논문에서 제시된 격자모델은 알칸과 계면활성제의 실험결과를 매우 잘 설명할 수 있다.

• 산업공학
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• 제16권4호
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• pp.463-472
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• 2003

In this study we consider the problem of MPS(master production planning) of TFT-LCD(Thin Film Transistor - Liquid Crystal Display) production factory. Due to the complexities of the TFT-LCD production processes, it is difficult to build effective MPS. This study presents an algorithm having a concept of IDPQ(Ideal Daily Production Quantity) that considers line balancing of TFT-LCD production process. In general, the MPS building procedure does not consider line balancing in non-bottleneck processes. MPS without considering line balancing may make ineffective schedule. We present algorithms for building MPS considering factory capacity and line balancing according to the sales order.