Sungmok Hwang

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HRIR Customization in the Median Plane Via Principal Components Analysis

A principal components analysis of the entire median HRIRs in the CIPIC HRTF database reveals tha... more

머리전달함수 데이터베이스를 이용한 음원 위치 추정 방법에 관한 연구 = Sound source lo- ocalization using HRTF database

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Sound Source Localization using HRTF database

제어로봇시스템학회 국제학술대회 논문집, Jun 1, 2005

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Customization of Head-Related Impulse Responses in the median plane for synthesizing moving sound

3D Sound Technology: Head-Related Transfer Function Modeling and Customization, and Sound Source Localization for Human–Robot Interaction

Time delay estimation from HRTFs and HRIRs

Time delay, which is a propagation time for arriving an acoustic wave emitted from a sound source... more Time delay, which is a propagation time for arriving an acoustic wave emitted from a sound source to an ear durum of listener, and Interaural-Time-Delay (ITD), which is the delay between two ears when acoustic waves reach each ear, are very important sound cues to perceive a sound source position. Therefore, it is essential to 3-D sound systems for formation of effective virtual sound. Time delay and ITD are well contained both in Head-Related-Transfer-Functions (HRTFs) and in Head-Related-Impulse-Responses (HRIRs). However, it is not easy to estimate the accurate time delay and ITD from HRTF and HRIR due to the coarse time resolution and the pinna effect. In this work, we compare the performance of several typical methods for time delay estimation and introduce a HRIR interpolation method to improve accuracy of estimation.

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Prediction of sound reduction of cabin unit for offshore facilities and ships

Proceedings of the Korean Society for Noise and Vibration Engineering Conference, 2013

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10kW 풍력발전기 블레이드 형상 개념 설계 및 타당성 검증

The Society for Aerospace System Engineering, Dec 1, 2017

Modeling, customization, and interpolation of head-related impulse responses based on principal components analysis = 주성분 분석법을 이용한 머리전달함수의 모형화, 맞춤 및 보간법

한국과학기술원, 2009

1.5 MW Wind Turbine Noise Measurement and Analysis of Low-Frequency Noise

Journal of the Korean society for New and Renewable Energy, Dec 31, 2018

The noise from a 1.5 MW wind turbine was measured and the apparent sound power level, tonal audib... more The noise from a 1.5 MW wind turbine was measured and the apparent sound power level, tonal audibility, and spectrum balance were analyzed. The apparent sound power level and tonal audibility were analyzed according to IEC 61400-11: ed3. (2012-11). The measured noise data at the turbine site was mainly in the north-west (NW) and north-north-west (NNW) directions, and approximately 500 and 250 samples of total noise and background noise data were obtained. Three tone components were observed in the low frequency region below 100 Hz. The tones in the low frequency critical band with a center frequency of 78.1 Hz were found to have a higher level than the hearing threshold. The possibility of wind turbine noise annoyance was also analyzed through the spectrum balance analysis.

유체유발, 음질,심리음향 : 보편적인 기저함수를 이용한 개인의 머리전달함수 모델링

주성분 분석법을 이용한 머리전달함수 모형화 기법의 성능 비교

Transactions of the Korean Society for Noise and Vibration Engineering, 2008

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Artificial Ear for Robots

2006 5th IEEE Conference on Sensors, 2006

Robots with sound localization capability have been developed mostly relying on machine vision or... more Robots with sound localization capability have been developed mostly relying on machine vision or an array of more than two microphones. Humans can localize a sound source hidden to the eye and distinguish whether a sound is coming from front or rear, above or below with only two ears. This is mainly due to the complex shape of the pinna. In particular, reflections off the posterior wall of the concha produce spectral notches at different frequencies in the headrelated transfer function (HRTF) as the sound source shifts in position. From the non-individualized HRTFs measured with a B&K HATS (head and torso simulator), we were able to confirm the relationship between the spectral notches and the geometry of the concha. Based on the observation of the HATS' pinna and resulting HRTFs, a novel design of artificial ear that can be mounted on a robot head is proposed in order to explore the possibility of developing sound localization sensors using only two microphones. Experimental results using a designed artificial ear show that the spectral notches are distinctively changed with respect to the elevation in the frontal region, whereas they disappear in the rear. In view of that result, it is expected to pinpoint a sound direction in 3-D space using only two microphones and the designed artificial ear can be a suitable mechanical sensor for sound source localization. I.

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Sound direction estimation using an artificial ear for robots

Robotics and Autonomous Systems, 2011

This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit:

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Modeling and Customization of Head-Related Impulse Responses Based on General Basis Functions in Time Domain

Acta Acustica united with Acustica, 2008

Abstract: This study deals with modeling and customization of head-related impulse responses (HRI... more

HRIR Customization in the Median Plane via Principal Components Analysis

A principal components analysis of the entire median HRIRs in the CIPIC HRTF database reveals tha... more

Modeling of individual head-related impulse responses using a set of general basis functions 황성목*·박영진† ·박윤식**

A principal components analysis (PCA) of the median head-related impulse responses (HRIRs) in the... more A principal components analysis (PCA) of the median head-related impulse responses (HRIRs) in the CIPIC HRTF database reveals that the individual HRIRs can be adequately reconstructed by a linear combination of 12 orthonormal basis functions. These basis functions can be used generally to model arbitrary HRIRs, which are not included in the process to obtain the basis functions. To clarify whether these basis functions can be used to model other set of arbitrary HRIRs, an numerical error analysis for modeling and a series of subjective listening tests were carried out using the measured and modeled HRIRs. The results showed that the set of individual HRIRs, which were measured in our lab using different measurement conditions, techniques, and source positions, can be well modeled with reasonable accuracy. Furthermore, all subjects reported not only the accurate vertical perception but also the front-back discrimination with the modeled HRIRs based on 12 basis functions. However, as ...

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10kW wind turbine blade aerodynamic design and verification

Time delay estimation from HRTFs and HRIRs

Time delay, which is a propagation time for arriving an acoustic wave emitted from a sound source... more Time delay, which is a propagation time for arriving an acoustic wave emitted from a sound source to an ear durum of listener, and Interaural-Time-Delay (ITD), which is the delay between two ears when acoustic waves reach each ear, are very important sound cues to perceive a sound source position. Therefore, it is essential to 3-D sound systems for formation of effective virtual sound. Time delay and ITD are well contained both in Head-Related-Transfer-Functions (HRTFs) and in Head-RelatedImpulse-Responses (HRIRs). However, it is not easy to estimate the accurate time delay and ITD from HRTF and HRIR due to the coarse time resolution and the pinna effect. In this work, we compare the performance of several typical methods for time delay estimation and introduce a HRIR interpolation method to improve accuracy of estimation.

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Development of Aerodynamic Shape Optimization Program for Horizontal Axis Wind Turbine Blade

In this paper, the aerodynamic design process of wind turbine blades is established. The optimiza... more In this paper, the aerodynamic design process of wind turbine blades is established. The optimization design strategy is presented and the constraints that must be reviewed during the aerodynamic design process are summarized. Based on this, this study developed a BEMT-based aerodynamic optimal design program that can be applied easily to actual work, not only for research purposes, but also can be integrated from the initial concept design stage to the final 3D shape detail design stage. The developed program AeroDA consisted of a concept design module, basic design module, optimal TSR module, local shape optimization module, performance analysis module, design verification module, and 3D shape generation module. Using the developed program, an improved design of the 5MW blade by NREL was made, and it was confirmed that this program could be used for design optimization. In addition, a 10kW blade aerodynamic design and turbine detailed performance analysis were carried out, and it ...

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