• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.580-582
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• 2002

A major problems of Switched Reluctance Motor(SRM) is torque ripple which causes undesirable acoustic noise and vibration. To reduce the torque ripple two different approaches are used. One is to modify a motor geometry, the other is to manipulate motor current to improve performance. This paper presents modifications of the rotor pole shape which reduces the torque ripple.

• 소음진동
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• 제7권3호
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• pp.499-509
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• 1997

During the process of oxide removal from work rolls in sheet metal manufacture, filamentary brushes frequently exhibit a bouncing or chatter behavior. The dynamics of this phenomenon is investigated through the development of expressions for the non-linear contact stiffness between the brush and the roll. With formulation of simple structural models, the time responses in the presence and absence of friction under random excitation are investigated. Possible solutions for the minimization or avoidance of this bouncing or chatter problem are also suggested.

• 대한전기학회논문지
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• 제35권11호
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• pp.503-510
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• 1986

A new algorithm based on the concept of prediction error minimization is suggested to estimate the time varying delay in discrete processes. In spite of the existence of the stochastic noise, this algorithm can estimate time varying delay accurately. Computation time of this algorithm is far less than that of the previous extended parameter methods. With the use of this algorithm, generalized minimum variance control shows good control behavior in simulations.

• 전자공학회논문지B
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• 제31B권10호
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• pp.32-43
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• 1994

This paper presents new QRD-based recursive least squares algorithms for bilinear lattice filter. Bilinear recursive least square lattice algorithms are derived by using the QR decomposition for minimization covariance matrix of predication error by applying Givens rotation to the bilinear recursive least squares lattics algorithms. The proposed algorithms are applied to the bilinear system identification to evaluate the performance of algoithms. Computer simulations show that the convergence properties of the proposed algorithms are superior to that of the algorithms proposed by Baik when signal includes the measurement noise.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅳ
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• pp.1799-1802
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• 2003

This paper has been studied a Adaptive feature-factors based fingerprints recognition in many biometrics. we study preprocessing and matching method of fingerprints image in various circumstances by using optical fingerprint input device. The Fingerprint Recognition Technology had many development until now. But, There is yet many point which the accuracy improves with operation speed in the side. First of all we study fingerprint classification to reduce existing preprocessing step and then extract a Feature-factors with direction information in fingerprint image. Also in the paper, we consider minimization of noise for effective fingerprint recognition system.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2004년도 봄 학술발표논문집 Vol.31 No.1 (B)
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• pp.805-807
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• 2004

본 논문에서는 노이즈 모델에 기반한 훼손된 얼굴 영상의 인증하는 방법을 제안한다. 제안된 방법은 먼저 학습 단계에서 노이즈 파라미터의 변화에 의해 훼손된 영상을 생성한다. 그 훼손된 영상과 노이즈 파라미터는 PCA에 의해 훼손된 영상과 노이즈 파라미터들의 선형 조합으로 표현된다. 테스트 단계에서는 훼손된 영상으로 LSM(Least-square minimization)방법을 적용하여 훼손된 영상의 노이즌 파라미터를 추정한다. 그리고 추정된 노이즈 파라미터를 가지고 원본 영상으로부터 합성된 영상을 생성하고, 그것을 테스트 영상과 인증한다. 실험 결과는 제안된 방법이 노이즈 파라미터를 정확하게 추정하여 얼굴 인증의 성능 개선 가능성을 보여준다.

• 대한전자공학회논문지SD
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• 제41권5호
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• pp.91-97
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• 2004

음성신호 대역을 처리할 수 있는 정밀도를 가지는 디지털 과표본화 잡음변형기를 설계하였다. 디지털 잡음변형기가 IP의 형태로서 최적화 된 설계가 되기 위해, 2.0 V의 저 전압에서 동작할 수 있고 하드웨어 소모면적을 최소화 할 수 있는 방안에 초점을 맞추어 디지털 데이터처리 동작을 위한 곱셈기능, ROM 구조 등의 회로설계를 최적화 할 수 있는 방안을 제시하였다. 설계 및 검증의 방법론에 있어서는 동작수준의 시뮬레이션을 통하여 전체 구조 및 내부 비트 수를 결정하였고, 트랜지스터 수준의 시뮬레이션을 통해 전체 타이밍과 최종 성능을 예측하였다. 또한 0.35-㎛ 표준 CMOS 공정으로써 테스트 칩을 제작한 후 측정하여 시뮬레이션 결과와 부합함을 확인함으로써 제안하는 회로와 설계 방법론이 효과적임을 검증하였다.

• International journal of advanced smart convergence
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• 제8권1호
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• pp.141-146
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• 2019

These days, there are many applications using neural networks as parts of their system. On the other hand, adversarial examples have become an important issue concerining the security of neural networks. A classifier in neural networks can be fooled and make it miss-classified by adversarial examples. There are many research to encounter adversarial examples by using denoising methods. Some of them using GAN (Generative Adversarial Network) in order to remove adversarial noise from input images. By producing an image from generator network that is close enough to the original clean image, the adversarial examples effects can be reduced. However, there is a chance when adversarial noise can survive the approximation process because it is not like a normal noise. In this chance, we propose a research that utilizes high-level representation in the classifier by combining GAN network with a trained U-Net network. This approach focuses on minimizing the loss function on high representation terms, in order to minimize the difference between the high representation level of the clean data and the approximated output of the noisy data in the training dataset. Furthermore, the generated output is checked whether it shows minimum error compared to true label or not. U-Net network is trained with true label to make sure the generated output gives minimum error in the end. At last, the remaining adversarial noise that still exist after low-level approximation can be removed with the U-Net, because of the minimization on high representation terms.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권6호
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• pp.2204-2224
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• 2021

This paper studies secure wireless transmission from a multi-antenna transmitter to a single-antenna intended receiver overheard by multiple eavesdroppers with considering the imperfect channel state information (CSI) of wiretap channel. To enhance security of communication link, the artificial noise (AN) is generated at transmitter. We first design the robust joint optimal beamforming of secret signal and AN to minimize transmit power with constraints of security quality of service (QoS), i.e., minimum allowable signal-to-interference-and-noise ratio (SINR) at receiver and maximum tolerable SINR at eavesdroppers. The formulated design problem is shown to be nonconvex and we transfer it into linear matrix inequalities (LMIs). The semidefinite relaxation (SDR) technique is used and the approximated method is proved to solve the original problem exactly. To verify the robustness and tightness of proposed beamforming, we also provide a method to calculate the worst-case SINR at eavesdroppers for a designed transmit scheme using semidefinite programming (SDP). Additionally, the secrecy rate maximization is explored for fixed total transmit power. To tackle the nonconvexity of original formulation, we develop an iterative approach employing sequential parametric convex approximation (SPCA). The simulation results illustrate that the proposed robust transmit schemes can effectively improve the transmit performance.

• 한국자동차공학회논문집
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• 제15권2호
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• pp.126-134
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• 2007

Although there has been substantial research on the squeal noise for the automotive brake system, robust design issues with respect to control factors equivalent to design variables in optimization, noise factors due to system uncertainties, and signal factors designed to accommodate a user-adjustable setting still need to be addressed. For the purpose, the robust design applied to the disk brake system has been investigated by DOE (Design of Experiments) based Taguchi analysis with dynamic characteristics. The specific goal of this methodology is to identify a design with linear signal-response relationship, and variability minimization. The finite element models of the disk brake assembly have been constructed, and the squeal noise problems have been solved by complex eigenvalue analysis. As the practical robust design to reduce the brake squeal noise, material properties of pad, disk, and backplate, thickness and geometry of pad are selected as control factors, material properties of pad and disk, and the contact stiffness have been considered as noise factors, and friction coefficient between pad and disk is chosen as a signal factor. Through the DOE based robust design, the signal-to-noise ratio and the sensitivity for each orthogonal array experiment have been analyzed. Also, it has been proved that the proposed robust design is effective and adequate to reduce the brake squeal noise.