• Interaction and multiscale mechanics
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• v.5 no.4
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• pp.399-405
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• 2012

A dissipative particle dynamics (DPD) simulation was presented to analyze surface wettability and contact angles of a droplet on a solid platform. The many-body DPD, capable of modeling vapor-liquid coexistence, was used to resolve the vapor-liquid interface of a droplet. We found a constant density inside a droplet with a transition along the droplet boundary where the density decreased rapidly. The contact angle of a droplet was extracted from the isosurfaces of the density generated by the marching cube and a spline interpolation of 2D cutting planes of the isosurfaces. A wide range of contact angles from $55^{\circ}$ to $165^{\circ}$ predicted by the normalized parameter ($|A_{SL}|/B_{SL}$) were reported. Droplet with the parameters $|A_{SL}|>5.84B{_{SL}}^{0.297}$ was found to be hydrophilic. If $|A_{SL}|$ was much smaller than $5.84B{_{SL}}^{0.297}$, the droplet was found to be superhydrophobic.

• Speech Sciences
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• v.10 no.2
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• pp.85-95
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• 2003

In speech signal processing, it is very important to detect the pitch exactly in speech recognition, synthesis and analysis. If we exactly pitch detect in speech signal, in the analysis, we can use the pitch to obtain properly the vocal tract parameter. It can be used to easily change or to maintain the naturalness and intelligibility of quality in speech synthesis and to eliminate the personality for speaker-independence in speech recognition. In this paper, we proposed a new pitch detection algorithm. First, positive center clipping is process by using the incline of speech in order to emphasize pitch period with a glottal component of removed vocal tract characteristic in time domain. And rough formant envelope is computed through peak-fitting spectrum of original speech signal infrequence domain. Using the roughed formant envelope, obtain the smoothed formant envelope through calculate the linear interpolation. As well get the flattened harmonics waveform with the algebra difference between spectrum of original speech signal and smoothed formant envelope. Inverse fast fourier transform (IFFT) compute this flattened harmonics. After all, we obtain Residual signal which is removed vocal tract element. The performance was compared with LPC and Cepstrum, ACF. Owing to this algorithm, we have obtained the pitch information improved the accuracy of pitch detection and gross error rate is reduced in voice speech region and in transition region of changing the phoneme.

• Journal of the Korea Computer Graphics Society
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• v.4 no.2
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• pp.1-13
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• 1998

The most important goal of character animation is to efficiently control the motions of a character. Until now, many techniques have been proposed for human gait animation, and some techniques have been created to control the emotions in gaits such as "tired walking" and "brisk walking" by using parameter interpolation or motion data mapping. This paper proposes a human running model based on a one-legged hopper with a self-balancing mechanism. The proposed technique exploits genetic programming to optimize movement, and can be easily adopted to various character models. We extend the energy minimization technique to generate various motions in accordance with emotional specification.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.389-392
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• 2008

This paper predicts the changes of natural frequencies due to the changes of mass at different point mass stations by using iterative calculation Transfer Matrices Method for different boundary conditions of a single beam structure (fixed-free and fixed-fixed beam). Firstly, the first three natural frequencies of an original beam are obtained using Transfer Matrices Method to verify the accuracy of the obtained results. The results are then compared with the exact solutions before purposely changing the parameter of mass. Both beams are modeled as discrete continuous systems with six-lumped-mass system. A single beam is broken down into a point mass and a massless beam which represent a single station and expressed in matrix form. The assembled matrices are used to determine the value of natural frequencies using numerical interpolation method corresponding to their mode number by manipulating some elements in the assembled matrix.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.10
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• pp.60-66
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• 2011

In this paper, we analyze the effects of estimation error in the active cancellation signal, which is intended to counter the pulsed-CW signal of a hostile radar. We also examine the effects of estimation error in maximum-likelihood estimation (MLE) and quadratic interpolation scheme from a radar signal active cancellation viewpoint. Then, we modify the correlation-based error compensation scheme which mitigates the estimation error of MLE to improve the performance of the active cancellation signal. Finally, we present simulation results to show that the correlation-based scheme has better performance than the other in terms of radar signal active cancellation.

• Journal of Computational Design and Engineering
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• v.3 no.2
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• pp.132-139
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• 2016

In this paper, a minimum time path planning strategy is proposed for multi points manufacturing problems in drilling/spot welding tasks. By optimizing the travelling schedule of the set points and the detailed transfer path between points, the minimum time manufacturing task is realized under fully utilizing the dynamic performance of robotic manipulator. According to the start-stop movement in drilling/spot welding task, the path planning problem can be converted into a traveling salesman problem (TSP) and a series of point to point minimum time transfer path planning problems. Cubic Hermite interpolation polynomial is used to parameterize the transfer path and then the path parameters are optimized to obtain minimum point to point transfer time. A new TSP with minimum time index is constructed by using point-point transfer time as the TSP parameter. The classical genetic algorithm (GA) is applied to obtain the optimal travelling schedule. Several minimum time drilling tasks of a 3-DOF robotic manipulator are used as examples to demonstrate the effectiveness of the proposed approach.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.931-931
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• 2012

제주지역의 강수자료는 최근에 이르러 69개 지점으로 증가하여 비교적 밀도있는 강수관측이 진행되고 있다. 그러나 기존의 자료 증설 내역과 이설 등으로 인해 과거로부터 현재에 이르는 자료를 기반으로 면적강수량을 산정할 경우 다소 어려움이 있다. 본 연구에서는 1992년부터 2010년까지의 강수자료를 바탕으로 관측소 개수를 기반으로 기간을 구분하여 각 기간별로 공간보간기법별로 면적강수량을 산정하고 이를 비교하였다. 사용한 공간보간기법은 PRISM(Parameter-elevation Regressions on Independent Slopes Model)기법과 티센(Thiessen)법으로 19년간의 일강수량 자료를 바탕으로 각각 면적강수량을 산정했다. PRISM기법을 이용한 경우는 고도, 관측점으로부터의 거리, 방향성 분석 및 해안가중치를 고려하여 계산하였고, 티센법의 경우는 기간별로 상이한 티센망을 구축하여 산정하였다. 지점 관측강수량에서 고도가 증가할수록 강수량이 증가하는 제주형 산악효과가 나타났으며 이는 보간기법에 의한 결과에서도 동일하게 나타나는 것으로 확인되었다. 또한 고도에 따른 상관성은 PRISM기법에 의한 결과에서 더 높게 산정되는 것으로 나타났다. 기법별 산정된 면적강수량은 근소한 차이를 보였으며 PRISM기법에 의한 값이 티센법에 비해 약 1%정도 크게 계산되었다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.11
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• pp.1118-1127
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• 2008

The position and size of holes in the partition of a double cavity are known to strongly affect the eigenfrequency of the longitudinal eigenmodes of the double cavity. To maximize or minimize the eigenfrequency of the hole-partitioned double cavity, two acoustical topology optimization problems are formulated and solved. While two sub-cavities are filled with air, a partition between them is assumed to consist of sub-partitions of variable acoustical properties. One design variable is assigned to each sub-partition, whose material properties are interpolated as those of an intermediate material between air and a rigid body. The penalty parameter of the used interpolation function is adjusted to obtain a distinct air and rigid body distribution at the converged stage in each acoustical topology optimization problem. A special attention is paid to the selection of initial values of design variables to obtain solutions as close to global optimum and symmetric as possible. To show numerical characteristics of these optimization problems, the formulated problems are first solved for the one-dimensional partition design domain and then for the two-dimensional partition design domain.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.12
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• pp.5978-5999
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• 2018

Pedestrian detection is a challenging area in the intelligent vehicles domain. During the last years, many works have been proposed to efficiently detect motion in images. However, the problem becomes more complex when it comes to detecting moving areas while the vehicle is also moving. This paper presents a variational optical flow-based method for motion estimation in vehicular traffic scenarios. We introduce a framework for detecting motion areas with small and large displacements by computing optical flow using a multilevel architecture. The flow field is estimated at the shortest level and then successively computed until the largest level. We include a filtering parameter and a warping process using bicubic interpolation to combine the intermediate flow fields computed at each level during optimization to gain better performance. Furthermore, we find that by including a penalization function, our system is able to effectively reduce the presence of outliers and deal with all expected circumstances in real scenes. Experimental results are performed on various image sequences from Daimler Pedestrian Dataset that includes urban traffic scenarios. Our evaluation demonstrates that despite the complexity of the evaluated scenes, the motion areas with both moving and static camera can be effectively identified.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.5
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• pp.1141-1162
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• 2024

Humidity is an important parameter in meteorology and is closely related to weather, human health, and the environment. Due to the limitations of the number of observation stations and other factors, humidity data are often not as good as expected, so high-resolution humidity fields are of great interest and have been the object of desire in the research field and industry. This study presents a novel super-resolution algorithm for humidity fields based on the Wasserstein generative adversarial network(WGAN) framework, with the objective of enhancing the resolution of low-resolution humidity field information. WGAN is a more stable generative adversarial networks(GANs) with Wasserstein metric, and to make the training more stable and simple, the gradient cropping is replaced with gradient penalty, and the network feature representation is improved by sub-pixel convolution, residual block combined with convolutional block attention module(CBAM) and other techniques. We evaluate the proposed algorithm using ERA5 relative humidity data with an hourly resolution of 0.25°×0.25°. Experimental results demonstrate that our approach outperforms not only conventional interpolation techniques, but also the super-resolution generative adversarial network(SRGAN) algorithm.