• The Journal of the Acoustical Society of Korea
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• v.22 no.8
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• pp.680-686
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• 2003

Digital waveguide model is a general method that is used in physical modeling of musical instruments. Wave motion is analyzed by time or by space in digital waveguide model. Because sampling is made via time, it is general that musical instrument model is described by wave motion of time. In this paper, we synthesized the musical instrument sound by adding instrument body model to the spatial based string model. In this way, we could improve sound quality and process musical instrument model's tone control variables effectively. We explained about delay error that happens in string and body in space based sampling and showed method to process fractional delay using FD (Fractional Delay)filter. Finally, we explained the relation between tone quality and number of delays. And we also compared the result with time base digital waveguide model.

• Journal of the Institute of Convergence Signal Processing
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• v.10 no.2
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• pp.127-131
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• 2009

In the digital waveguide theory, traveling waves are represented by general solution to the wave equation that is second-order linear partial differential equation. The movement of these waves can be implemented using only delay lines. An unit delay in the general digital waveguide describes a sampling time interval. However, in the space-based digital waveguide the unit delay implies the spatial sampling distance. In consideration of these differences between two models, it is known that the space-based digital waveguide model is adequate to synthesize pitch-shifted sounds such as vibrato because the propagation distance can be directly control. In this paper, the time-based digital waveguide model which also synthesizes pitch-shifted sounds is proposed and compared with space-based digital waveguide.

• The Journal of the Acoustical Society of Korea
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• v.20 no.1
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• pp.3-12
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• 2001

In physical modeling of plucked string instruments, the vibration of a string is typically simulated by the linear system. Currently the Digital Waveguides of J.O.Smith[1] are widely used to get a high quality sound of the plucked string instrument. He used the wave equation to derive the Digital Waveguides and emphasized the time variable. In this thesis, new model of plucked string is proposed to improve the sound quality emphasizing the spatial variable of the wave equation. In our model, we used the fixed sampling interval which is not dependent on the speed of the wave. So we could get more detailed description of wave movement by the time variable. As a result, the new model could produce a higher quality sound of plucked string instrument.

• The Journal of the Acoustical Society of Korea
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• v.23 no.7
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• pp.521-531
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• 2004

In this paper we developed the Physical modeling of the Sanio Gayageum using the improved digital waveguide theory. The frequency characteristics of the Gayageum body is implemented by an inverse filtering and the impulse response of the body. We obtained the synthesis sounds of the unit sound for the Gayageum using the simulation of the straight-line fits by the changes of the fundamental frequencies depending on the Amok location. Finally. we could obtain the virtual Sanio Gayageum sounds similar to the actual Gayageum by tuning the Amok positions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.564-566
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• 2012

In this paper, a design method for a compact broadband planar monopole antenna fed by coplanar waveguide (CPW) is studied. The proposed broadband monopole is optimized for terrestrial digital television (DTV) receiving. The monopole is fed by a CPW with 75-ohm characteristic impedance on an FR4 substrate and its size is $100mm{\times}200mm$. A pair of slit is appended for size reduction and an inductive stub is loaded for the impedance matching between the feedline and monopole. The optimized monopole antenna for DTV band (470-806 MHz) is fabricated on an FR4 substrate and tested experimentally to verify the results of this study.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.9
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• pp.1996-2002
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• 2013

In this paper, a design method for a compact broadband planar monopole antenna fed by a coplanar waveguide (CPW) is studied. The proposed broadband monopole is optimized for terrestrial digital television (DTV) reception. In order to achieve broadband characteristics, the monopole and ground conductor are gradually tapered. By loading slit pairs on both monopole and ground plane, the proposed antenna is miniaturized. The monopole is fed by a CPW with 75-ohm characteristic impedance on an FR4 substrate and its size is $100mm{\times}200mm$. The optimized monopole antenna for DTV band (470-806 MHz) is fabricated on an FR4 substrate and tested experimentally to verify the results of this study.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8A
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• pp.688-696
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• 2005

An antenna was designed and manufactured for the DBS receiver system. This antenna is a planar or flat antenna which shows many advantages over the conventional parabolic antenna such as higher aperture efficiency, easier installation and improved aesthetics to name a few. The antenna is a novel design employing microstrip annular ring resonating antenna elements and a radial waveguide feeder network. The LNB(Low Noise Blockdown Converter) is can integrate with the antenna iしt the back of the radial waveguide. The 35cm diameter antenna works at 31.8dBi minimum gain which implies an aperture efficiency of around $80\%$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.10a
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• pp.55-56
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• 2017

In this paper, a wideband loop antenna is designed using a CPW feeding method for indoor digital TV applications. The proposed loop antenna consists of a square loop and two circular sectors which connect the loop with central feed points, and the CPW feed line is inserted in the lower circular sector. The CPW feed line is designed to match with the 75 ohm port impedance for DTV applications, and the ground slots are etched in order to improve the impedance matching in the middle frequency region. The optimized antenna is fabricated on FR4 substrate, and the experiment results show that it operates in the frequency band of 463-1,280 MHz for a VSWR < 2, which assures the operation in the DTV band.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06e
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• pp.19-22
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• 1998

인공 잔향은 콘서튼홀에서와 같이 수백.수천개의 극점과 영점들을 갖는 커다란 시스템을 모델링하기 위한 신호처리 분야 중에서 매우 매력적인 응용 분야중 하나이다. 이러한 인공잔향을 구현하기 위하여, 기존에는 순환적인 디지털 필터인 Comb 필터와 Allpass 필터를 조합시킨 인공 잔향기가 제안되어 왔다. 그러나, 이와 같은 방법은 시스템이 커질수록 실시간 처리와 안정도의 문제가 제기되고, 인공 잔향의 특성이 저하되는 문제점이 있다. 따라서, 최근에는 이와 같은 문제점을 효과적으로 감소시킬 수 있는 귀환 지연 회로망(Feedback Delay Networks : FDN's)과 디지털 도파관 회로망(Digital Waveguide Networks : DWN's)를 이용한 방법이 제안되어지고 있다. 그러므로, 본 연구에서는 귀환 행렬이 Circulant 행렬로 이루어진 귀환 지연 회로망(CFDN's)를 이용한 인공 잔향기 구현에 관하여 논의하고자 한다.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.291-294
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• 2004

본 논문에서는 Smith에 의해 제안된 이중 지연 라인을 갖는 양방향 디지털 도파관 모델을 SDL(sing1e delay line)모델로 변환하여 가야금의 단위 음이 만들어지는 과정을 나타내었다. 각 단계의 시스템은 선형적이며 단일 지연 라인과 LPF로 구성된다. 가야금의 임펄스 응답을 기본 입력신호로 하였으며. 실제 가야금의 조율 시스템인 안족은 선분 적합성을 이용한 근사화 과정을 거쳐 구현하였으며 이를 이용한 모의실험을 하였다. 실제 가야금을 조율하듯 안족에 의한 조율과 실제 음과 유사한 단위 음 생성을 할 수 있었다.