• 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.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10b
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• pp.169-171
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• 2003

네트워크의 빠른 발전으로 인해 분산된 공간 데이터의 질의 처리 연구가 활발히 진행되었다. 하지만 이런 질의 처리 환경에서는 질의 처리의 최적화를 위한 정확한 정보를 수집하기 어렵고 네트워크 상태의 불확실성으로 인해 데이터의 전송 상태를 예측하기가 힘들다. 이런 동적인 환경에 적응하기 위해서는 기존의 공간 조인 기법을 수정할 필요가 생겼다. 특히 기존의 공간 조인 기법은 처리 방식이 비대칭적(asymmetric)이기 때문에 데이터 전송의 지연으로 인해 처리가 잠시 중단되거나 빠른 응답 시간을 보장할 수 없다. 본 논문에서는 분산 공간 데이터베이스에서의 공간 조인의 문제점을 해결하기 위해서 대칭적인 해시 공간 조인을 사용하는 적응적 공간 조인 기법을 제안한다. 제안된 기법은 초기의 전송된 데이터들을 조인하여 조인 결과를 빠르게 보여주며 데이터 전송의 지연 시에는 이미 전송된 데이터 중 조인되지 않은 객체들을 조인함으로써 지속적으로 조인을 수행한다.

• 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.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.909-915
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• 2008

Researches for time delay estimation had been studied broadly. However studies about factors for time delay estimation are insufficient, especially in case of real environment application. In 1997, Brandstein and Siverman announced that performance of time delay estimation deteriorates as reverberant time of room increases. Even though reverberant time of room is same, performance of estimation is different as the specific part of signals. In order to know that reason, we studied and analyzed the factors for time delay estimation using speech signal and room impulse response. In result, we can know that performance of time delay estimation is changed by different R/D ratio and signal characteristics in spite of same reverberant time.

• The Journal of the Acoustical Society of Korea
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• v.33 no.2
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• pp.118-125
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• 2014

An approximation of speed of sound in the measurement plane is essential for the inverse estimation of temperature. To this end, an inverse problem relating the measured retarded time data in between set of sensors and actuators array located on the wall is formulated. The involved transfer matrix and its coefficient vectors approximate speed of sound of the measurement plane by using the radial basis function with finite number of interpolation points deployed inside the target field. Then, the temperature field can be reconstructed by using spatial interpolation technique, which can achieve high spatial resolution with proper number of interpolation points. A large number of retarded time data of acoustic paths in between sensors and arrays are needed to obtain accurate reconstruction result. However, the shortage of interpolation points due to practical limitations can cause the decrease of spatial resolution and deterioration of the reconstruction result. In this works, a regeneration for obtaining the additional retarded time data for an arbitrary acoustic path is suggested to overcome the shortage of interpolation points. By applying the regeneration technique, many interpolation points can be deployed inside the field by increasing the number of retarded time data. As a simulation example, two rectangular duct sections having arbitrary temperature distribution are reconstructed by two different data set: measured data only, combination of measured and regenerated data. The result shows a decrease in reconstruction error by 15 % by combining the original and regenerated retarded time data.

• Journal of Industrial Convergence
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• v.20 no.7
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• pp.57-64
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• 2022

There are various structures in the underground space, and the structures is managed as 3D data in Integrated Underground Geospatial Map Management System(IUGMMS). The worker transmits and updates the integrated map including the changed underground geospatial data to IUGMMS with the completed book submission program. However, there is a problem in that the transmission time and the update time is delayed because the size of the integrated map file is large. In this paper, we try to extract and transmit only the changed integrated map by obtaining and comparing each spatial characteristic information of the integrated map. As a result of the experiment, the transmission time of the suggestion method is short and the update time is also short than the transitional method because the suggestion method transmits only the integrated map including the changed underground geospatial data. As a result, it was possible to reduce the delay time in transmitting and updating the changed integrated map.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.1
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• pp.115-126
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• 2019

Recently, in order to solve the traffic congestion in urban areas and to improve the peripheral environment, research on the design and construction technology development of great depth underground double-deck tunnel is under way by using the underground space in the urban area. The network type double-deck tunnel is in the form of an intersection with a small cross section and a steep slope as per construction at the base of a flatland, so that the fire smoke spreads rapidly in case of fire, which is expected to cause damage of human life. Therefore, this study is analyzed the delay effect of fire smoke diffusion according to the installation and non - installation of delay system for fire smoke diffusion at the intersection. Fire fumes were delayed up to 270 seconds when the delay system for fire smoke diffusion was installed at the intersection and it is analyzed that the greater the operating area of the delay system for fire smoke diffusion, the more preventable the damage of human life of the intersection.

• Explosives and Blasting
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• v.32 no.2
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• pp.1-8
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• 2014

In this study, 16 test blastings had been carried out with different spacings, burdens, drilling lengths, and charges per delay for investigating the characteristics of ground vibration propagation, which depends on the delay time. From the tests, it was possible to derive a ground vibration equation. Using the equation, the characteristics of ground vibration could be investigated by analyzing the nomogram and predicting the Peak Particle Velocity (PPV), which are influenced by the delay time and the priming location. The trend of ground vibration change depending on the delay time was analyzed for the standards charges of 0.5, 1.6, 5, and 15 kg, which were suggested in "Blasting design and construction guidelines to road construction" by the Ministry of Land, Infrastructure and Transport. From the study, it would be possible to suggest a favorable vibration control method, which depends on the charge.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.5
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• pp.326-332
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• 2003

This paper deals with a model reduction for linear systems with time varying delayed states. A generalized controllability and observability gramians are defined and obtained by solving linear matrix inequalities. Using the generalized controllability and observability gramians, the balanced state space equation is realized. The reduced model can be obtained by truncating states in the balanced realization and the upper bound of model approximation error is also presented. In order to demonstrate efficacy of the suggested method, a numerical example is performed.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.2
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• pp.253-260
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• 2015

Love which is one of the emotional of mankind, has been studied in sociology and psychology as a matter of grate concern. In this paper we represent romantic behaviors in the love equation of Romeo and Juliet as time series and phase portraits in the case of with and without time delay. And we also analyze their difference.