• 한국정보통신학회논문지
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• 제20권1호
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• pp.131-141
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• 2016

SRM은 저비용, 간단한 자기구조, 넓은 운전속도, 높은 효율, 직류전원과의 우수한 결합성 등의 장점을 가진 전동기구이다. SRM의 토오크는 자속의 방향과는 무관하여 자기구조의 배치가 유연한 특성을 가지고 있어 다양한 자기구조를 가지고 있다. 본 논문에서는 자속방향에 따라 Radial-Flux SRM와 Axial-Flux SRM로 크게 나누었고 기계적인 구조의 차이에 따라 Radial-Flux SRM에는 Conventional, Segmented stator and rotor, Double stator SRM 로, 그리고 Axial-Flux SRM에는 C-core stator와 Axial-airgap SRM로 분류하였고 각각에 대해 비교 해석하여 적절한 용도에 최적의 자기구조를 선택할 수 있도록 각각의 기본적인 특성을 제시하였다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권3호
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• pp.51-64
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• 2015

In the present study, we develop two history matching techniques based on Markov chain Monte Carlo method where radial basis function and Gaussian distribution generated by unconditional geostatistical simulation are employed as the random walk transition kernels. The Bayesian inverse methods for aquifer characterization as the developed models can be effectively applied to the condition even when the targeted information such as hydraulic conductivity is absent and there are transient hydraulic head records due to imposed stress at observation wells. The model which uses unconditional simulation as random walk transition kernel has advantage in that spatial statistics can be directly associated with the predictions. The model using radial basis function network shares the same advantages as the model with unconditional simulation, yet the radial basis function network based the model does not require external geostatistical techniques. Also, by employing radial basis function as transition kernel, multi-scale nested structures can be rigorously addressed. In the validations of the developed models, the overall predictabilities of both models are sound by showing high correlation coefficient between the reference and the predicted. In terms of the model performance, the model with radial basis function network has higher error reduction rate and computational efficiency than with unconditional geostatistical simulation.

• 설비공학논문집
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• 제19권12호
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• pp.874-882
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• 2007

The effects of a guide fin blade on the flow characteristics in a ventilating axial fan were investigated experimentally. The guide fins were setup onto the pressure surface of the blade, and their effects on the flowrate were evaluated. Two types of the guide fin blade were designed. One is the stem fin blade, and the other is the radial fin blade. The stem fin is designed normal to the circumference of a circle, and the radial fin is designed along the circumference of a circle. The results from the guide fin blade fans are compared with that of the blade without guide fins. The position and the geometry of the radial fin setting up on the blade have an effect on the increase of flowrate with the minor sacrifice of rotational speed of the blades. The radial fin positioning at 0.84 times blade diameter shows highest performance in the flowrate. The increase of the blade weight resulting from applying the guide fins shows minor effect on the variation of rotational speed of the blades.

• 한국통신학회논문지
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• 제29권12C호
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• pp.1660-1668
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• 2004

본 논문에서는 간단한 구조, 적은 계산량과 안정된 빠른 수렴속도를 가진 RBF (Radial Basis Function) 신경회로망을 이용한 이중 임계값 방식의 음성구간 검출기 알고리즘을 제안하고 시뮬레이션을 통해 유용성을 확인하였다. 음성압축기에 사용되는 CELP (Code-Excited Linear Prediction) 파라미터들을 신경회로망 입력으로 하여 잡음에 강하게 반응하게 하였고, 음성구간 검출기의 성능향상을 위해 음성구간과 침묵구간에서 다른 임계값을 사용하는 이중 임계값 방식을 적용하였다. 실험 결과 이중 임계값을 이용한 RBF 신경망 음성구간 검출기는 G.729 Annex B 음성구간 검출기 보다 우수한 성능을 보였고, 기존의 MLP (Multi Layer Perceptron) 신경회로망을 이용한 음성구간 검출기와 비교하여 음성구간에서는 비슷한 성능을 보였으나 침묵구간에서 25% 정도의 성능향상을 보였다.

• 전기학회논문지
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• 제61권1호
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• pp.135-142
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• 2012

In this paper, we proposed a new architecture called radial basis function-based polynomial neural networks classifier that consists of heterogeneous neural networks such as radial basis function neural networks and polynomial neural networks. The underlying architecture of the proposed model equals to polynomial neural networks(PNNs) while polynomial neurons in PNNs are composed of Fuzzy-c means-based radial basis function neural networks(FCM-based RBFNNs) instead of the conventional polynomial function. We consider PNNs to find the optimal local models and use RBFNNs to cover the high dimensionality problems. Also, in the hidden layer of RBFNNs, FCM algorithm is used to produce some clusters based on the similarity of given dataset. The proposed model depends on some parameters such as the number of input variables in PNNs, the number of clusters and fuzzification coefficient in FCM and polynomial type in RBFNNs. A multiobjective particle swarm optimization using crowding distance (MoPSO-CD) is exploited in order to carry out both structural and parametric optimization of the proposed networks. MoPSO is introduced for not only the performance of model but also complexity and interpretability. The usefulness of the proposed model as a classifier is evaluated with the aid of some benchmark datasets such as iris and liver.

• Applied Microscopy
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• 제50권
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• pp.17.1-17.9
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• 2020

Recent advances in fabrication have enabled radial-junction architectures for cost-effective and high-performance optoelectronic devices. Unlike a planar PN junction, a radial-junction geometry maximizes the optical interaction in the three-dimensional (3D) structures, while effectively extracting the generated carriers via the conformal PN junction. In this paper, we report characterizations of radial PN junctions that consist of p-type Si micropillars created by deep reactive-ion etching (DRIE) and an n-type layer formed by phosphorus gas diffusion. We use electron-beam induced current (EBIC) microscopy to access the 3D junction profile from the sidewall of the pillars. Our EBIC images reveal uniform PN junctions conformally constructed on the 3D pillar array. Based on Monte-Carlo simulations and EBIC modeling, we estimate local carrier separation/collection efficiency that reflects the quality of the PN junction. We find the EBIC efficiency of the pillar array increases with the incident electron beam energy, consistent with the EBIC behaviors observed in a high-quality planar PN junction. The magnitude of the EBIC efficiency of our pillar array is about 70% at 10 kV, slightly lower than that of the planar device (≈ 81%). We suggest that this reduction could be attributed to the unpassivated pillar surface and the unintended recombination centers in the pillar cores introduced during the DRIE processes. Our results support that the depth-dependent EBIC approach is ideally suitable for evaluating PN junctions formed on micro/nanostructured semiconductors with various geometry.

• 한국음향학회지
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• 제42권1호
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• pp.25-31
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• 2023

능동소나를 이용하여 수중물체의 속도를 추정하려면 Continuous Wave(CW) 펄스를 이용하는 것이 일반적이나, 수중물체의 속도가 느리고 근거리의 해양에서는 잔향음의 영향으로 수중물체의 속도 추정이 용이하지 않다. 2017년도에 Wang 연구진은 이를 극복하고자 수중물체의 속도에 의한 도플러 변이에 둔감한 광대역 신호인 Hyperbolic Frequency Modulation(HFM) 펄스 두 개를 상반된 스윕방향으로 이용하였다. 두 펄스 간 송신 시간간격과 탐지시간 차이의 변화를 통하여 수중물체 속도 추정이 가능하다는 것을 시뮬레이션으로 제시하였다. 하지만 동일한 대역을 이용하므로 상호상관성에 의해서 수중물체 탐지 성능이 영향을 받을 수 밖에 없다. 상호상관성에 의한 수중물체 탐지 성능저하를 방지하기 위하여 대역이 분리된 상반된 스윕방향의 두 HFM 펄스 이용을 제안한다. 본 논문에서는 상반된 스윕방향의 두 대역 HFM을 이용하여 수중물체의 시선속도 추정에 관한 이론을 도출하였고, 펄스길이와 대역폭이 1 s와 400 Hz인 HFM 펄스로 시뮬레이션을 수행하였다. 제안한 방법을 이용하여 수중물체의 시선속도를 추정하면 약 6 %의 오차로 표적 속도 추정이 가능하다는 것을 시뮬레이션을 통하여 확인하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(1)
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• pp.244-247
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• 2000

This paper deals with methods for partial response maximum-likelihood (PRML) detection and crosstalk cancellation. In accrodance with the demand for increased recording density, 20 gigabyte (Gbyte) digital versatile disk (DVD) ROM channel is considered. Channel is modelled to be close to real optical channel using DIFFRACT$\^$TM/. After comparing the spectral characteristics of various PR polynomials, P(D)=1＋D＋D$^2$＋D$^3$is proposed as a target PR. The performance of the system is illustrated under the condition that the readout signal is degraded by crosstalk, radial tilt and nonlinear distortions in optics. The experimental results show that crosstalk and nonlinear distortions degrade performance by about 2dB, respectively. We also show that when radial tilt is added to the crosstalk, the performance degradation assumes quite significant proprotions.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.594-597
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• 2007

The notebook system use the radial fan to cool the main chipsets which generate heat. It needs to improve cooling performance by increasing fan RPM or increasing fan volume. But the former accompanies acoustic noise problem and the latter has a limitation due to notebook height and cooling area. So this study shows fatal parameters in the fan performance view point, and optimization process with Design Of Experiment. With this result, the fan CFM increases with same size of fan and we can use it as a result of decreasing fan acoustic noise.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.199-199
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• 2000

Most of linear time-varying(LTV) systems except special cases have no general solution for the dynamic equations. Thus, it is difficult to design time-varying controllers in analytic ways, and other control design approaches such as robust control have been applied to control design for uncertain LTI systems which are the approximation of LTV systems have been generally used instead. A robust control method such as quantitative feedback theory(QFT) has an advantage of guaranteeing the stability and the performance specification against plant parameter uncertainties in frozen time sense. However, if these methods are applied to the approximated linear time-invariant(LTI) plants which have large uncertainty, the designed control will be constructed in complicated forms and usually not suitable for fast dynamic performance. In this paper, as a method to enhance the fast dynamic performance, the approximated uncertainty of time-varying parameters are reduced by the proposed QFT parameter-scheduling control design based on radial basis function (RBF) networks for LTV systems with bounded time-varying parameters.