• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.213-216
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• 1999

완벽한 가상 현실을 재현하려면 사람의 오감을 실제 세계 수준으로 정교하게 재현해야 한다. 현재 시각 효과는 상당히 발전해 있으나, 청각적, 음향적 부분은 아직도 발전 정도가 상대적으로 낮다. 가상 현실을 위한 음향은 크게 HRTF등을 이용한 음상 정위와, 음장 재현으로 나눌 수 있다. 본 논문에서는 가상 현실 체험자의 이동에 따라 효과적으로 음장을 재현하는 방법에 대해 논하고자 한다. 본 논문에서 제안하는 시스템은 크게 전처리 부분과 실시간 처리 부분으로 구성되어 있으며 전처리 과정에서 음장을 계산하여 실시간 처리 부분에서 체험자의 위치를 추적하여 음장을 재현한다.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.197-200
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• 2000

본 논문은 VR시스템에 사용되는 실시간 음향제시를 위한 시스템 구현에 관한 것이다. 2개의 Speaker 또는 헤드폰을 사용하여 음상제어, 음장제어의 두 부분으로 구성되어 있다. 음상제어 부분은 각각의 음원의 위치를 정위하고, 음장제어 부분은 레이 트레이싱(Ray Tracing)기법을 이용하여 음장을 시뮬레이션하고 가상 공간의 음장 파라미터를 추출하여 음원에 적용하면서 실시간으로 음장효과를 렌더링 한다. 이 시스템은 펜티엄-Ⅱ333MHz 시스템에서 구현하였다. 최종적으로 청취자는 2개의 스피커 또는 헤드폰을 이용하여 3D음장을 경험하게 된다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.06a
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• pp.53-54
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• 2014

본 논문에서는 멀티채널 오디오 재생시스템을 구성하는 라우드스피커들이 표준위치와 상이한 위치에 존재할 경우 입력된 멀티채널 오디오 신호가 표현하는 음장감을 최대한 유지하면서 주어진 라우드스피커 배치환경에 최적으로 가상음원과 멀티채널 오디오 신호를 재생하는 방법을 제안한다. 능동잡음제어 기술에 이용되는 LSM 기술을 활용하여 원음장과 스피커를 통해 재생되는 복원음장 사이의 오차를 최소화하는 음향공간필터를 설계하여 적용하였으며, 청취평가를 통하여 음장감이 유지됨을 확인하였다.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.257-260
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• 2004

HRTF 를 사용하여 가상적인 음향 효과를 내는 시스템에서의 음의 왜곡은 필수적이다. 하지만 음성과 같은 사람이 민감하게 느끼는 부분에서의 음의 선명도 저하는 다른 대역의 왜곡보다 더욱 크게 느껴진다. 그리고 모노 및 두 채널의 주파수 특성이 비슷한 스테레오에서는 음질을 보상할 수 없다는 단점이 있다. 본 논문에서는 이러한 음의 선명도의 저하를 유발하게 하는 가상 음향 발생 필터의 특징을 분석하고, 간단한 필터 설계에 의해서 본래의 가상 음향을 그대로 유지하면서 선명도를 높일 수 있는 방법을 제시한다. 제시한 방법은 특히 모노 및 뉴스모드와 같이 음성이 많이 들어 있는 부분에서 뛰어난 성능을 보인다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.6
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• pp.562-567
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• 2010

A passenger vehicle has various and complicated transmission paths of sound and vibration. In order to identify the mechanism of transfer path, estimation of excitation force and exact modeling of transfer path are required. In this paper vector synthesis technique is employed to identify the characteristics of road noise and its transmission to vehicle compartment through noise and vibration analysis. Vibration reduction efficiency of each transfer path is evaluated by comparing individual vector components obtained virtual simulation. The degree of effect is used to estimate the contribution of vibration input components to total output. And in this paper presents a new technique based on simulation studies using vector synthesis diagram and design of experiments, by which the effects of magnitude and phase change of input paths can be predicted.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.2005-2011
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• 2003

Introducing the interfacial pressure jump terms based on the surface tension into the momentum equations of two-phase two-fluid model, the system of governing equations is turned mathematically into the hyperbolic system. The eigenvalues of the equation system become always real representing the void wave and the pressure wave propagation speeds as shown in the previous manuscript. To solve the interfacial pressure jump terms with void fraction gradients implicitly, the conventional semi-implicit method should be modified as an intermediate iteration method for void fraction at fractional time step. This advanced semi-implicit method (ASIM) then becomes stable without conventional additive terms. As a consequence, including the interfacial pressure jump terms with the advanced semi-implicit method, the numerical solutions of typical two-phase problems can be more stable and sound than those calculated exclusively by using any other terms like virtual mass, or artificial viscosity.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.596-600
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• 2009

We are developing a simple low-cost wind velocity sensor based on small microphones. The sensor system consists of 4 microphones covered with specially shaped wind screens, 4 pre-amplifiers that respond to low frequency, and a commercial sound interface with multi channel inputs. In this paper, we first present the principle of the sensor, i.e., technique to successfully suppress the influence of external noise existing in the environment in order to determine the wind velocity and the wind direction from the output from a microphone. Then, we present an application for generating realistic motions of a virtual tree swaying in real wind. Although the current sensor outputs significant leaps in a measured sequence of directions, the interactive animations demonstrate that it is usable for such applications, if we could reduce the leaps to some degree.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.11
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• pp.1071-1077
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• 2010

The reduction of the vehicle interior noise has been the main interest of noise and vibration harshness(NVH) engineers. A passenger vehicle has various and complicated transmission paths of sound and vibration. In order to identify the mechanism of transfer path, estimation of excitation force and exact modeling of transfer path are required. This paper presents method for estimating the noise source contribution on the road noise of the vehicle in a multiple input system where the input sources may be coherent with each other. And vector synthesis technique is employed to identify the characteristics of road noise and its transmission to vehicle compartment through noise and vibration analysis. Vibration reduction efficiency of each transfer path is evaluated by comparing individual vector components obtained virtual simulation.

• Transactions of Materials Processing
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• v.26 no.5
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• pp.300-305
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• 2017

In this paper, a design method for an intermediate die was developed to manufacture a hollow linear motion guide rail in mandrel drawing process based on virtual die method and backward tracing scheme. FE simulations and mandrel drawing experiments using Mn55Cr carbon steel were performed to prove the effectiveness of the proposed design method. Results of FE simulations and experiments showed that the proposed design method could lead to drawn products with sound shape and the highest dimensional precision.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.75-80
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• 1998

This paper proposes a novel computer human interface, named Virtual Wireless Microphone (VWM), which utilizes computer vision and signal processing. It integrates real-time face tracking and sound signal processing. VWM is intended to be used as a speech signal input method for human computer interaction, especially for autonomous intelligent agent that interacts with humans like as digital secretary. Utilizing VWM, the agent can clearly listen human master's voice remotely as if a wireless microphone was put just in front of the master.