Evaluation of three different standard head-related transfer functions using an elevation discrimination task for virtual sources displayed in the median plane

Hyun Jo,William L. Martens,Youngjin Park 제어로봇시스템학회 2010 제어로봇시스템학회 국제학술대회 논문집 Vol.2010 No.10

The performance in controlling elevation effect of virtual sources displayed in the median plane was tested for three different sets of standard head-related transfer functions (HRTFs) using an elevation discrimination task. The three candidate sets compared included a representative subject’s customized head-related impulse response (HRIR), mean-HRIR derived from the CIPIC database, and mean-HRIR of individually customized HRIRs proposed by Jo et al. [7]. The goal of the current study was to find the best standard HRTF dataset for many listeners, with particular emphasis on its ability to work well without requiring a given listener to engage in any customization procedure. A two interval two alternative forced choice (2-AFC) discrimination for virtual source elevation was used to find how easy it was for subjects to distinguish between elevation angles within 15 or 30 degrees of each other. The simple question asked of each subject was “Which sound source is perceived as higher between the two presented.” To compare the performance of elevation discrimination, individually measured HRTF, individually customized HRTF, and HRTF of KEMAR dummy were also used. The results from six subjects showed that even though the listeners’ own measured HRTFs were used, they could not discriminate elevation well for sources differing only in terms of polar angle in the median plane. Similar poor performance was observed when using HRIRs from KEMAR. With regard to the search for standard filters for general use across listeners, a representative subject’s customized HRTF, which was based on the method provided by Hwang, et al. [8] was preferred as it supported the best discrimination performance between the tested candidate HRTF datasets.

APROXIMATION OF HEAD RELATED TRANSFER FUNCTION USING PROLATE SPHEROIDAL HEAD MODEL

Hyun Jo,Youngjin Park,Youn-sik Park 한국소음진동공학회 2008 한국소음진동공학회 국제학술대회논문집 Vol.2008 No.7

Optimization of Spherical and Spheroidal Head Model for Head Related Transfer Function Customization

Hyun Jo,Youngjin Park,Youn-sik Park 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10

Researchers have used a spherical head model to construct a HRTF (Head Related Transfer Function), which has a single adjustable parameter (radius of head) for HRTF customization mainly because of its simplicity. By using the mathematical form to calculate analytic spheroidal HRTF for an incident point source, a spheroidal head model can be used for near-field HRTF customization with two adjustable parameters (head width and head height). To see the necessity of head height consideration, two analytic solutions; spherical HRTF and spheroidal HRTF, are compared with a measured HRTF (KEMAR’ HRTF). By varying head dimensions and ear offsets, notch frequency pattern is calculated. Through optimization procedure, we find an optimal parameters which minimizes notch pattern error between the estimated head notch pattern and notch pattern of measured HRTF. In the view point of magnitude of HRTF, performance of spherical head model and spheroidal head model is compared. Modeling error is reduced by using a spheroidal head model instead of the conventional spherical one.

Novel alleles of KAS//-A and FAD2-JA from EMS-induced mutant lines produces elevated level of palmitic and oleic acid in soybean

Hyun Jo,Jiyoung Park,Sooyeon Kim,Taemin Kim,Jong Tae Song,Jeong-Dong Lee 한국육종학회 2023 한국육종학회 공동학술발표집 Vol.2023 No.-

Analysis of Individual Differences in Head-Related Transfer Functions by Spectral Distortion

Hyun Jo,Youngjin Park,Youn-sik Park 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8

The inter-subject variability of Head-Related Transfer Function (HRTF) needs to be good considered for elevation perception of the sound image. This work investigates the variability of HRTF based on spectral distortion. As the representative of human subjects, CIPIC HRTF database was used for calculating spectral distortions between subjects. In the frequency range from 0Hz to 14 kHz, a small spectral distortion was obtained at high elevation angles. At front and rear source positions, spectral distortion is larger than the case of high elevation source positions. Some 1/3 octave bands, the similar results were obtained under 11.3kHz band when the same analysis is performed on 1/3 octave band frequency scale. To give a high-fidelity virtual impression without HRTF customization, Multi-channel speakers are needed at front and rear source positions because of large variations of HRTF. Moreover, when dimension reduction technique (for example, principal component analysis) is applied for HRTF database, the analysis should be focused on the region of high spectral distortion.

Evaluation of yield, agronomic and seed characteristics of rice under fence based agro-photovoltaic system in South Korea

Hyun Jo,Junbeom Park,Thi Cuc Nguyen,Hai Anh Tran,Jong Tae Song,Jeong-Dong Lee 한국육종학회 2023 한국육종학회 공동학술발표집 Vol.2023 No.-

Phase Transformation Modeling for Hypo Peritectic Steel in Continuous Cooling

Jun‑hyun Jo,Kyung‑woo Yi 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7

Phase change of steel during cooling affects the slab qualities in continuous casting. Especially, crack susceptibility of hypoperitectic steel is high because large volume shrinkage occurs by peritectic phase transformation during solidification andcooling. In continuous cooling, phase change is different from the behaviors under the equilibrium condition, such as undercoolingand extend of peritectic reaction, etc. Therefore, we develop a new phase change model considering thermodynamics,empirical equations, and carbon diffusion in each phase to predict phase change behavior during continuous cooling. Inthis model, phase change of hypo peritectic steel comprises 5 stages until all phases become the γ phase. The velocities ofthe δ/γ interface and phase fractions during cooling are calculated according to cooling rate, undercooling of the γ phase,and carbon contents. The results show that if solidification ends by the δ phase during dTp,the γ phase is formed by massivetransformation. On the contrary, if peritectic reaction starts with liquid, the γ phase is formed and grows by diffusionaltransformation. In latter case, massive transformation of remaining δ phase can occur with high undercooling or very fastcooling rates. This analysis shows that there are several different paths depending on carbon contents of hypo peritectic steels.

Numerical Analysis on Crack Generation Behavior of Hypo Peritectic Steel in Continuous Casting Process

Jun‑hyun Jo,Min‑seok Park,Kyung‑woo Yi 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.11

Hypo peritectic steels exhibit a high possibility of longitudinal crack during continuous casting. Therefore, many researchershave studied the mechanisms of crack generation in hypo peritectic steel. Stress in solidified shell, or volume contractionwith small liquid fractions were suggested as the mechanisms of crack generation. A new model was developed for predictingpossibility of crack generation by calculating strain rates in solid, volume contraction rate during solidification, and theprobability of liquid unfilling in continuous cooling processes. The results show that massive transformation from the δphase to the γ phase, and peritectic transformation during solidification can be the main crack generation mechanisms. Furthermore,a linear relationship exists between the amount of undercooling for peritectic transformation (dTp) and the carboncontent of the boundary for dividing the two crack generation mechanisms. Additionally, the longitudinal crack ratios ofthe field results are analyzed through strain rates in solid and liquid unfilling possibilities. Relative positions in the range ofhypo peritectic steel and effective carbon contents are suggested to analyze the crack ratio of steels with alloying elements. This analysis shows that the results obtained from the new models for crack generation possibility are usable, and dTpcangenerate the behavioral differences in crack generation according to the conditions.

애니메이션 연출의 서정적 표현에 관한 연구 : 마이클 두독의 "아버지와 딸"을 중심으로

김현조(Kim Hyunjo),김현조(Kim Hyunjo) 한국디지털디자인학회 2011 디지털디자인학연구 Vol.11 No.4

디지털 기술의 발달은 우리의 상상력을 뛰어 넘는 제작기법을 통하여 대중성 및 오락성을 갖춘 비쥬얼적 즐거움을 주고 있다. 과거 기술적 한계에 의해 표현할 수 없었던 장면들이 이제는 스크린 속에서 대중들과 만나고 있다. 사실적인 캐릭터의 움직임 배경표현 그리고 비쥬얼 효과 등의 디지털제작기법들은 애니메이션 기술적 표현의 경계를 허물며 대중들에게 시각적 청각적 즐거움을 제공해 주고 있다. 그러나 디지털 기술에 의해 표현되어지는 영상이미지만으로는 인간의 감성을 전달하기에는 한계성을 가지고 있다. 우리가 오래된 사진을 보고 과거를 회상하면서 그리움에 잠기는 것은 디지털 기술에 의해 표현되어진 이미지에 의해서가 아니라 작품 속에서 보여주는 화면구도 카메라 연출 그리고 스토리연출 등 요소들에 의해 만들어진 영상이미지가 인간본연의 감정을 자극하여 인간이 인간으로서 당연히 가져야 할 감정들을 느끼게 하기 때문이다. 이러한 서정적 표현은 인간이라는 주관적인 대상이 작품이라는 객관적 소재와 하나가 되어 인간본연의 감정에 흠뻑 빠지게 하는 것이다. 따라서 본 논문은 마이클 두독 감독의 "아버지와 딸"에서 보여준 화면구성 카메라 연출 스토리 연출이라는 세 가지 요소를 통해 감독 자신의 주관적인 생각과 경험들을 어떻게 객관적인 애니메이션 작품 소재속에서 서정적으로 표현되었는지 분석을 하였다. The development of digital technology provides visual enjoyment with entertainment popularity through production techniques that go beyond our imagination. Scenes that could never be expressed by technical limitations in the past are meeting the public now in the screen. Digital production techniques that includes realistic character movements background expressions and visual effects are having broken the boundaries of animation technical expressions and provided audio-visual enjoyment to the public. But video images that are expressed by digital technology have the limitation of conveying human emotions to the audience. when we look at old picture we usually recollect the past and indulge in yearning about it. because video images that represented by screen layout camera storytelling techniques arouse feelings of human nature and make people feel human emotion as a human being. the lyrical expression that "human" a subjective target and "animation" a objective subject matter all in one makes people indulge in emotion as human nature. So in this paper I analyzed how the lyrical expressions were shown on Michael dudok de bits' Father and Daughter with screen layout camera shot and story produce.

Ultrasonic Beam Propagation in Highly Anisotropic Materials Simulated by Multi-Gaussian Beams

Hyunjo Jeong,Lester W. Schmerr,Jr 대한기계학회 2007 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.21 No.8

The necessity of nondestructively inspecting fiber-reinforced composites, austenitic steels, and other inherently anisotropic materials has stimulated considerable interest in developing beam models for anisotropic media. The properties of slowness surface play a key role in the beam models based on the paraxial approximation. In this paper, we apply a modular multi-Gaussian beam (MMGB) model to study the effects of material anisotropy on ultrasonic beam profile. It is shown that the anisotropic effects of beam skew and excess beam divergence enter into the MMGB model through parameters defining the slope and curvature of the slowness surface. The overall beam profile is found when the quasilongitudinal (qL) beam propagates in the symmetry plane of a transversely isotropic gr/ep composite. Simulation results are presented to illustrate the effects of these parameters on ultrasonic beam diffraction and beam skew. The MMGB calculations are also checked by comparing the anisotropy factor and beam skew angle with other analytical solutions.