• 한국통신학회논문지
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• 제21권5호
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• pp.1274-1282
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• 1996

This paper deals with an inverse modeling of nonminimum phase communication channel utilizing the HOS (High Order Statistics) of the received signal. After the communication channel is separated into the minimum phase and maximum phase components, the inverse modeling is performed independently. The performance superiority is confirmed by monte-carlo computer simulation in comparison with the traditional CMA (Constant Modulus Algorithm) method. By utilizing the proposed algorithm employing the HOS of the received signal, the inverse frequency characteristics of the channel can be obtained withoug transmitted signal in digital communication. This algorithm is required in preprocessing or postprocessing in order to remove the channel effect, and effective in the self adaptive equalizer which can minimize the bit error rate or symbol error rate in the recovry of received signal.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.561-565
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• 2000

This paper deals with dynamic walking and inverse dynamic analysis of the IWR biped walking robot. The system has nine bodies of the multibody dynamics. and all of the .joints of them are made up of the revolute joints at first. The problem of redundant constraint in double support phase is solved by changing the type of the joints considering kinematic relation. To make sure of its dynamic walking, the movement of balancing weight is determined by which satisfies not only the condition of ZMP by applying the principle of D'Alembert but also the contact condition of the ground. The modeling of IWR and dynamic walking are realized using DADS.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제4권2호
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• pp.172-175
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• 2004

Generally, the yield rate of semiconductors is the major factor that affects directly the price of semiconductors. For a high yield rate of semiconductors, the air inside clean room is needed to be purified and high efficient filters are used for this. The filter are made of super-fine fiber and certain pinholes can be easily produced on the filter's surface by inadvertent manufacturing. As these pinholes are not easily detected with the bare sight, these pinholes exert a negative impact to filtration performance of the filter. In this research, not only the automatic test equipment for detecting pinholes is proposed, but also inverse modeling scheme based on artificial neural network is applied for tuning of its important parameters.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.283-287
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• 1996

The exhaust noise reduction of automobile with the active muffler is experimentally investigated. The control algorithm is the filtered-x LMS algorithm and the inverse algorithm with the adaptive line enhancer. Also, the control efficiency is increased with synthesized second harmonic engine frequency. In the experiment, the active muffler is applied to the end of exhaust system in automobile and the control with on-line secondary path modeling method(inverse algorithm) is compared the control of off-line secondary path modeling method. As secondary path transfer functions are changed, the experimental results show that the control performance with on-line method is more efficient than that with off-line method in the exhaust noise reduction of automobile.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1704-1709
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• 2000

This paper proposes a spherical probe allowing acoustic intensity measurements in three dimensions to be made, which creates a diffracted field that is well-defined, thanks to analytic solution of diffraction phenomena. Six microphones are distributed on the surface of the sphere along three rectangular axes. Its measurement technique is not based on finite difference approximation, as is the case for the ID probe but on the analytic solution of diffraction phenomena. In fact, the success of sound source identification depends on the inverse models used to estimate inverse diffraction phenomena, which has non-linear properties. In this paper, we introduce the concept of nonlinear inverse diffraction modeling using a neural network and the idea of 3 dimensional sound source identification with several tests.

• 한국멀티미디어학회논문지
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• 제18권7호
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• pp.886-894
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• 2015

In this paper, we conduct sensitivity analysis of parameters used for inverse modeling in order to estimate the PM₁₀ emissions from the 16 areas in East Asia accurately. Parameters used in sensitivity analysis are R, the observational error covariance matrix, and B, a priori (background) error covariance matrix. In previous studies, it was used with the predetermined parameter empirically. Such a method, however, has difficulties in estimating an accurate emissions. Therefore, an automatically determining method for the most suitable value of R and B with an error measurement criteria and posteriori emissions accuracy is required. We determined the parameters through a sensitivity analysis, and improved the accuracy of posteriori emissions estimation. Inverse modeling methods used in the emissions estimation are pseudo inverse, NNLS (Nonnegative Least Square), and BA(Bayesian Approach). Pseudo inverse has a small error, but has negative values of emissions. In order to resolve the problem, NNLS is used. It has a unrealistic emissions, too. The problems are resolved with BA(Bayesian Approach). We showed the effectiveness and the accuracy of three methods through case studies.

• 전력전자학회논문지
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• 제13권1호
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• pp.1-8
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• 2008

상태 공간 평균화법을 이용하여 절연형 inverse-SEPIC(Isolated Inverse-SEPIC)의 동적 모델링을 정립하고, 그 제어특성을 해석한다. 정상 상태 해석을 통해 회로의 주요 소자들에 대한 설계식을 유도한다. 근 궤적과 주파수 해석을 통해 II-SEPIC의 동특성 및 제어 특성을 파악하여, 적절한 제어성능을 가지는 제어기를 설계한다. 본 논문에서 제시하는 방법에 따라 설계된 II-SEPIC의 회로파라미터 및 전압제어기를 포함한 전체 제어시스템의 시뮬레이션과 실험을 수행한다. 시뮬레이션과 실험결과는 논문에서 제시한 모델링 및 제어기 설계방법의 타당성 및 유용성을 확인시켜 주고 있다.

• 한국차세대컴퓨팅학회논문지
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• 제13권4호
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• pp.112-123
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• 2017

전자전 상황에서 수신기의 수집 변수를 토대로 RF 위협체를 역추적함으로서 효율적인 전자공격을 수행하려는 연구가 진행되고 있다. 본 논문에서는 다양하고 구체적인 전자전 상황에서 위협체 역추적 알고리즘의 성능을 검증할 수 있도록 하기 위하여, 전자파 수집 변수를 바탕으로 레이더 위협체, 전자전 수신기, 전자파 전송환경과 같은 전자전 구성 단위들의 기능을 모델링하여 전자전 송수신 시뮬레이터를 구축한다. 시뮬레이터의 실험 결과는 수 m 정도의 거리 추적 오차와 소수점 이하 크기의 각도 추적 오차를 보이며, 모노펄스 빔폭과 편각의 변화에 따른 각도 추적 오차의 변화가 이론적인 모델링의 결과와 동일한 양상을 보임으로써 레이더 위협체의 거리 및 각도 추적의 동작 원리가 시뮬레이터에 적절하게 반영되었음을 확인할 수 있다. 구축한 전자전 송수신 시뮬레이터는 전자전 수집 시스템에서 추출된 위협체의 특성 변수가 실제 위협체의 특성 변수에서 어떻게 변형되었는지를 관찰하고, 다양한 전자전 상황에서 수집된 변수를 토대로 구성한 위협체 역추적 시스템의 성능을 평가하는 데에 활용될 수 있다.

• 소음진동
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• 제8권3호
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• pp.542-552
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• 1998

The noise sources, structure-borne and/or air-borne, in machinery can be defined by their locations and strengths. However the locations of that noise sources are well known in many cases. In those cases, the problem can be defined as an inverse problem to known the strengths of the noise sources in the frequency domain, the modeling scheme is classified by thecoherent or incoherent source. This paper expands the basic concept to the case of the complex noise sources, in which the set of coherent and incoherent noise sources are matched with the noise of a real vehicle. The error factors in the experiment and the optimal number of the monopole sources to match the real suond filed are also investigated. The results of the noise source modeling of heavy machinery show that the incoherent and coherent/incoherent source models are applicable to the high frequency and the low frequency region, respectively. The noise source model also enables the noise source analysis to rank the contribution of real source group such as engine, T/M, exhuast, etc.

• 비파괴검사학회지
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• 제25권3호
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• pp.157-162
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• 2005

In order to evaluate the corrosion of reinforcing steel-bars (rebar) in concrete, a nondestructive evaluation by the half-cell potential method is currently applied. In this study, potentials measured on a concrete surface are compensated into those on the concrete-rebar interface by the inverse boundary element method (IBEM). Because these potentials are obtained three-dimensionally (3-D), 3-D visualization is desirable. To this end, a visualization system has been developed by using VRML (Virtual Reality Modeling Language). As an application, results of a reinforced concrete (RC) slab with corroded rebars are visualized and discussed.