• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 1986년도 정기총회 및 제3회 학술연구발표회 요지집
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• pp.12-12
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• 1986

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 추계종합학술대회
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• pp.473-476
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• 2005

본 논문은 잡음에 강한 다양한 특징 파라메타를 제안한다. 기존의 음성인식에서 사용되는 특징 파라메타 MFCC(Mel Frequency Cepstral Coeeficient)는 좋은 성능을 보인다. 그러나 잡음에 보다 강인한 성능을 위해 기존에 사용되는 파라메타 MFCC의 특징공간을 변형시키는 알고리즘인 PCA(Principal Component Analysis)와 ICA(Independent Component Analysis)를 사용하여 특징 공간을 변형시킨 파라메타와 기존의 파라메타 MFCC의 성능을 비교하였다. 그 결과 ICA에 의해 변형된 특징 파라메타가 PCA로 변형된 파라메타와 MFCC보다 우수한 성능을 보였다.

• The Journal of the Acoustical Society of Korea
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• 제20권1E호
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• pp.31-37
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• 2001

Matched Field Processing (MFP) is a successive process of correcting mismatches between true and assumed parameters by matching the measured acoustic field data with numerically simulated data which we call replica. The MFP is widely used both in geo-acoustic parameter inversions and in source localizations. Whether a certain parameter can be inverted effectively or whether a source can be localized correctly depends on the amount of the influence that a parameter has on the acoustic field during the matching process. Sensitive parameters can be better estimated than the less sensitive ones in MFP. On the contrary, the sensitive parameters affect adversely on the source localization results when they have uncertainties. In this paper, a sensitivity index is defined based upon the field variation resulting from the perturbed parameters. Numerical test results show that the index behaves in accordance with the results of source localization under a mismatched environment and also with the inversion solutions.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1242-1244
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• 1999

AVR parameter tuning for voltage control of power system generators has generally been done with the open-circuit model of the synchronous generator. When the generator is connected on-line and operating at rated load conditions, the AVR operates in an entirely different environment from the open-circuit conditions. This paper describes a new method for AVR parameter tuning using optimization technique with on-line linearized system model. As this method considers not only the on-line models but also the off-line open-circuit models, AVR parameters tuned by this method can give the sufficiently stable performance at the open-circuit commissioning phase and give the desired performance at the operating conditions. Also this method estimates the optimum parameters for desired performance indices that are chosen for satisfying requirements in some practical applications, the performance of the AVR can satisfy the various requirements.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2005년도 국제학술대회
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• pp.381-385
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• 2005

Characterization of particle behavior is becoming more important in performance evaluation of water treatment system as well as in operation of the system because conventional parameter, turbidity has lack of explaining ability on small sized microorganisms such like Cryptosporidium etc. Accordingly, particle counter has been introduced in evaluation and operation of the treatment system. However researches on the relationship between turbidity, particle count and/or different sand/anthracite sizes have not been concurrent. Therefore in this study, the relationship was investigated to improve performance evaluation of sand filter so as to help choosing sand/anthracite effective size as a design parameter of water treatment facility. According to the results, too small or too large effective size media filter reached to turbidity limit(0.1 NTU)earlier. However, because shallow sand layer may cause early breakthrough, the depth of sand layer should be provided enough in order to compromise water quality and productivity.

• Structural Engineering and Mechanics
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• 제85권6호
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• pp.825-835
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• 2023

The effective buckling length factor is an important parameter in the elastic buckling analysis of steel structures. The present article aims at developing a new method that allows the determination of the buckling factor values for frames. The novelty of the method is that it considers the interaction between the bracing and the elastic supports for asymmetrical frames in particular. The approach consists in isolating a critical column within the frame and evaluating the rotational and translational stiffness of its restraints to obtain the critical buckling load. This can be achieved by introducing, through a dimensionless parameter 𝜙_i, the effects of coupling between the axial loading and bending stiffness of the columns, on the classical stability functions. Subsequently, comparative, and parametric studies conducted on several frames are presented for assessing the influence of geometry, loading, bracing, and support conditions of the frame columns on the value of the effective buckling length factor K. The results show that the formulas recommended by different approaches can give rather inaccurate values of K, especially in the case of asymmetric frames. The expressions used refer solely to local stiffness distributions, and not to the overall behavior of the structure.

• 한국ITS학회 논문지
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• 제5권2호
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• pp.1-10
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• 2006

본 논문에서는 강인한 음성인식 기술의 하나인 모델 파라미터 변환 기법 중 Carnegie Mellon University(1996)에서 Moreno가 제안한 최신 VTS(Vector Taylor Series) 알고리즘을 이용하여 주어진 잡음 환경에서 실험하였다. 이러한 VTS 알고리즘의 성능평가를 위해서 기존의 잡음 처리 방법 중 CMN(Cepstral Mean Normalization) 기법을 도입하였으며, 데시벨별로 설정한 백색 잡음과 거리잡음을 환경잡음으로 주어졌을 때의 인식률을 비교하였다. 또한 기존 Moreno가 제안한 실험환경의 인식 결과와 본 논문에서의 실험결과를 비교 분석하였다. 인식 알고리즘으로는 실시간 구현이 가능한 이산HMM(Hidden Markov Model)을 사용하였다.

• 해양환경안전학회지
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• 제24권3호
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• pp.325-331
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• 2018

This paper deals with the dynamical analysis of a vessel that leads to capsize in regular beam seas. The complete investigation of nonlinear behaviors includes sub-harmonic motion, bifurcation, and chaos under variations of control parameters. The vessel rolling motions can exhibit various undesirable nonlinear phenomena. We have employed a linear-plus-cubic type damping term (LPCD) in a nonlinear rolling equation. Using the fourth order Runge-Kutta algorithm with the phase portraits, various dynamical behaviors (limit cycles, bifurcations, and chaos) are presented in beam seas. On increasing the value of control parameter ${\Omega}$, chaotic behavior interspersed with intermittent periodic windows are clearly observed in the numerical simulations. The chaotic region is widely spread according to system parameter ${\Omega}$ in the range of 0.1 to 0.9. When the value of the control parameter is increased beyond the chaotic region, periodic solutions are dominant in the range of frequency ratio ${\Omega}=1.01{\sim}1.6$. In addition, one more important feature is that different types of stable harmonic motions such as periodicity of 2T, 3T, 4T and 5T exist in the range of ${\Omega}=0.34{\sim}0.83$.

• 한국자동차공학회논문집
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• 제7권6호
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• pp.144-155
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• 1999

An occupant analysis code SAFE (Safety Analysis For occupant crash Environment) is utilized to simulate and improve the crash performance of an energy absorbing steering system. The safety standard FMVSS 203 is simulated and used for design evaluations . Segments and contact elliposids are utilized to model the bod blocks and the components of the steering system with SAFE. Spring-damper elements and force-deflection characteristics are utilized to model the energy absorbing components such as the plate and the polyacetal molding. The plate absorbs the impact energy through tensile deformation . Whereas, the polyacetal molding absorbs the impact energy through compression. the body block test is carried out to validate tie simulation model, and real component tests are performed to extract the force-deflection curves . After the model is validated , the parameter study is carried out to evaluate the crash performance of the energy absorbing components. A performance measure is defined for the parameter study. Using the results of the parameter study and managing the orthogonal arrays, optimum design values of energy absorbing components are determined to minize the occupant injury.

• 한국물환경학회지
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• 제25권4호
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• pp.530-538
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• 2009

The Oxic-Settling-Anaerobic (OSA) treatment process, a modified Conventional Activated Sludge (CAS) process, was developed for the purpose of sludge reduction. The insertion of a sludge holding tank into a sludge return line, an anaerobic reactor, forming an OSA process, may provide a cost-effective way of reducing excess sludge production during a process. The OSA process was evaluated for its sludge reduction ability by kinetic parameter and mass balance, with an observed excess sludge reduction of 63.5%, as $P_{X.VSS}$, compared with the conventional activated sludge process.