• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.12
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• pp.184-190
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• 2013

Parametric stereo(PS) audio coding is a specific version of spatial audio coding. In this paper, the problem due to the conventional synthesis of phase differences. In the conventional upmix matrix, phase differences are synthesized not only on downmix signal but also ambient signal, which violates the assumption that the ambient signals are anti-phased. Deterioration due to the phase synthesis is analyzed, especially, for low interchannel correlation. To solve this problem, new upmix matrix is proposed, which synthesizes phase differences only on downmix signal. The performance of the proposed upmix matrix is verified by the subjective listening tests.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.4
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• pp.417-424
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• 2010

This study proposes a parametric modeling method for efficient preliminary design of FCM(Free Cantilever Method) bridge. The method is capable of automatic fitting of cross section according to variation of span length of box girder which has variational section. Parameters for forming longitudinal geometry of box girder are defined, then implicit and explicit constraints, and functional relations among them are defined by applying statistics of parameters used in FCM bridge designs. The constraints and relations are applied to a sample bridge for verifying applicability of parametric modeling. In addition, material quantity of the sample model generated by parametric modeling is estimated and compared to the quantity of the real designed model to check the accuracy of the automatically designed parametric model.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.1
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• pp.1-8
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• 2018

The purpose of this study is to implement modeling by applying the parametric technique to the atypical trusses of rigid retractable large space structures. The retractable large space structure requires a lot of time and skill in modeling nonlinear shapes or generating, interpreting, and reviewing many models by alternative. To solve these problems, we introduce firstly parametric modeling tool, secondly, we analyze the connection of atypical three-dimensional trusses of a rigid retractable large-space structure, and finally model it as parametric components of the developed trusses. Therefore, it is a future study to make effective modeling of the openable roof by developing the components that can realize the modeling of the truss classified by the opening and closing method, respectively.

• The Journal of the Acoustical Society of Korea
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• v.32 no.4
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• pp.294-300
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• 2013

In this paper, we present performance analysis results of parametric array communication system in terms of theoretical BER and channel capacity of MIMO in underwater AWGN channel by using simplified SNR of difference frequency. The SNR of the difference frequency is calculated by using transmission loss, noise level, and source level of difference frequency in which nonlinear effect is considered. By assuming primary frequencies as 210 kHz and 190 kHz, difference frequency as 20 kHz, transducer diameter as 0.1 m, and noise level as 50 dB and the requested BER as $10^{-4}$, we obtain parametric array communication range gains over the communication system using primary frequency of 59.11 km in fresh water and 5 km in sea water, respectively. Also we obtain range gains of 38.84 km and 46.38 km in fresh water, and 3.88 km and 4.38 km in sea water when we use SISO and $2{\times}2$ MIMO parametric array communications for the channel capacity of 10 bps/Hz.

• The Journal of the Acoustical Society of Korea
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• v.32 no.4
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• pp.287-293
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• 2013

We present a parametric array signal generating system using $3{\times}16$ transducer array which is composed of multi-resonant frequency transducers of 20kHz and 32.5kHz. To drive transducer array, sixteen channel amplifier using LM1875 chips is designed and implemented, and the PXI system based on the LabView 8.6 for arbitrary signal generation and analysis is used. Using the proposed system, we measure sound pressure level and beam pattern of difference frequency and verify the nonlinear effect of difference frequency. The theoretical absorption range and the Rayleigh distance are 15.51m and 1.933m, respectively and we verify that sound pressure of difference frequency is accumulated and increased at the near-field shorter than the Rayleigh distance. We verify that the beam pattern of the measured difference frequency and the beam pattern obtained by the superposition of two primary frequencies are similar, and high directional parametric signal was generated.

• The Journal of the Acoustical Society of Korea
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• v.34 no.2
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• pp.117-129
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• 2015

A parametric array is a nonlinear phenomenon that generates a narrow beam of low-frequency sound using the nonlinearity of the medium. The low-frequency sound so generated has a low sound pressure compared with that of sound generated directly. Consequently, a transducer that can generate a primary wave with high directivity and level is required. This study designed, fabricated, and evaluated a multi-resonance transducer as a parametric array source. The designs of the unit transducers and array transducer were based on an analysis model. The design process was repeated to fabricate the optimum transducer. The fabricated transducer array can generate a 189 dB, 190 dB primary wave level at 6.3 m and a 134 dB difference frequency wave using the parametric array phenomenon. The difference frequency wave has a frequency of 15 kHz and high directivity with an $8^{\circ}$ half power beam width in a $12{\times}18{\times}10m$ water tank.

• Korean Journal of Optics and Photonics
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• v.14 no.2
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• pp.175-183
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• 2003

We obtain a solution of optical parametric amplification using self-phase modulation within the Kerr media in a nonlinear interferometer with two arms. We show that it is equivalent to the solution driven by four-wave mixing and that the solution of parametric amplification is suitable to generate a parametric gain. We obtain a derivative of power gain with respect to the propagation distance and show that gain-saturation can occur as the beam propagates along the nonlinear arms. We also show a bandwidth characteristic of the parametric amplification driven by nondegenerate four-wave mixing. Numerical examples are given to illustrate that the solution of the parametric amplification can be applied to design and analysis of all-optical devices such as all-optical amplifiers.

• KIPS Transactions on Software and Data Engineering
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• v.10 no.10
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• pp.407-420
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• 2021

Deep neural networks are widely used to solve various problems. However, the deep neural network with a deep hidden layer frequently has a vanishing gradient or exploding gradient problem, which is a major obstacle to learning the deep neural network. In this paper, we propose a parametric activation function to alleviate the vanishing gradient problem that can be caused by nonlinear activation function. The proposed parametric activation function can be obtained by applying a parameter that can convert the scale and location of the activation function according to the characteristics of the input data, and the loss function can be minimized without limiting the derivative of the activation function through the backpropagation process. Through the XOR problem with 10 hidden layers and the MNIST classification problem with 8 hidden layers, the performance of the original nonlinear and parametric activation functions was compared, and it was confirmed that the proposed parametric activation function has superior performance in alleviating the vanishing gradient.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.709-711
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• 2005

이 논문에서는 CATIA, PRO-E 등의 CAD에서 3D 모델을 생성할 때 사용하는 파라메트릭 솔리드 모델링 기법에서 일반적으로 사용하는 방법보다 모델링 데이터의 용량을 크게 줄일 수 있는 방법에 대하여 고찰한다. 3D 파라메트릭 솔리드 모델링 기법은 기본적인 상세 솔리드들을 생성하여 부울(Boolean) 연산으로 이들을 조합하여 복잡한 형상(geometric object)을 만드는데 이 과정에서 많은 부울 연산이 수행된다. 그런데 각각의 상세 솔리드들의 크기가 필요 이상으로 크게 만들어 짐으로써 생성된 모델의 데이터 용량이 방대하게 되고 생성시간에도 영향을 미친다. 여기에서는 실무 경험을 바탕으로 처음에 생성된 상세 솔리드의 불필요한 부분을 제거하여 부울 연산에 알맞은 크기로 변경하여 모델링 데이터의 용량을 줄이는 방법을 제안한다.

• Korean Architects
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• s.572
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• pp.118-121
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• 2016

저번 회에서는 Barclays Center의 그린루프의 디자인 과정을 개략적으로 살펴보았습니다. 소음 저감의 목적으로 인하여 도출되었던 두 가지의 변수(새로운 루프의 중량과 두 겹의 루프사이에 위치하는 빈 공간)및 기존의 바클레이 센터가 가지고 있는 물리적인 특성(파라펫 및 기존 루프의 형상)을 고려하여 design surface를 설정하였고, 중량에 대한 조건 및 주변의 고층 주거빌딩들로 인해 일반적인 루프와는 다른 미적인 특이성을 고려하여 그린 루프라는 큰 방향을 제시하고, 양방향 곡면의 특성을 가지는 루프의 지오메트리와 시공 상의 복잡함과 공기의 단축을 위해 모듈로 이루어진 시스템을 제안하게 되었습니다. 이번 회에서는 루프의 디자인을 진행함에 있어서 어떠한 제약 조건이 있었으며 그러한 제약 조건들이 최종적인 루프 디자인 및 패턴에 어떠한 영향을 미쳤는지, 그리고 이러한 과정에서 파라메트릭 툴이 어떻게 사용되었는지에 대해 자세히 살펴보도록 하겠습니다. 이어서 다음 회에서는 디자인 측면에서가 아닌 pre-construction의 측면에서 시공상의 시행착오를 줄이고 공기를 단축하기 위한 목적으로 파라메트릭 툴의 사용하여 시뮬레이션을 했던 과정에 대해 자세히 알아보도록 하겠습니다.