• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.9
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• pp.842-849
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• 2011

The human ear canal amplifies the sound pressure level at specific frequency bands. The characteristics of the ear canal are very similar to those of curved cylindrical tube. In this study, the characteristics of sound transfer in human ear canal were measured and the acoustical space of ear canal was reproduced from the canal cavity geometry. For the measurement of sound transfer function in ear canal, a probe microphone and a reference microphone were used. The sound transfer functions were measured for 5 human subjects. To reproduce the acoustical space of the ear canal, two kinds of ear simulator were designed. The first one is a straight cylindrical tube type and the other is a real-shape ear of which geometry was taken from a micro-CT scanning of a human ear. The characteristics of the reproduced apparatus were compared with those of the human and a commercial ear simulator, RA0045 of G.R.A.S. Inc. The comparison results show that the developed apparatus well represent the ear canal characteristics in the low frequency, but have limited coincidence in level over high frequency range.

• Proceedings of the Korean Society of Computer Information Conference
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• 2014.01a
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• pp.425-426
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• 2014

충격소음(Impulse Noise) 측정 시 지그(Ear Simulator)가 자체적으로 음압측정에 미치는 영향을 확인하기 위해 지그를 이용하여 실내에서 충격소음을 측정하였다. 측정의 신뢰성과 정확성을 확보하기 위해 마이크로폰과 지그에서 동일조건에서 동시에 데이터를 수집하였다. 추가로 헤드&토르소에서 실험을 실시하였다. 최대음압레벨과 1/3옥타브 밴드 결과를 비교분석함으로써 측정 방법에 따른 차이점을 발견하였다.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1996.04b
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• pp.126-132
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• 1996

A laboratory scale hot strip rolling wear simulator(HRWS) was developed for the purpose of investigating the tribological phenomena occurred in production hot strip rolling mills. The HRWS' main parts are the electric heater, the mechanical descaler, tandem type 2-4Hi rolling mill stands, the cooling chamber, the tension controller and coiler. By simulating the tribelogical phenomena in rolling process at laboratory, wear patterns, cracks, cat-ear wear, black film, effect of hot rolling oil lubrication, etc. were reproduced, and discussed on the performace of simulator.

• The Journal of the Acoustical Society of Korea
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• v.11 no.2
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• pp.15-27
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• 1992

The standard measuring method of the frequency characteristics of headphones has been needed because different results come from the different measuring methods because of the lack of the reasonable measuring method of headphone characteristics, for example, in the case of psycho-acoustic experiments with headphones. In this paper, based on this fact, we studied the measurement method of headphones based on the natural hearing condition of human being, that is in situ measuring method, by measuring the headphone frequency characteristics using an artificial ear and a newly proposed device, HATS(Head And Torso Simulator). From the result of this paper, we could see that the method appropriate to a so called in situ condition was the one wi9th HATS, Because HATS simulated more correctly the acoustic impedance of the ear and the diffraction effect of the human head than the artificial ear.

• Journal of the Korea Society of Computer and Information
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• v.19 no.6
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• pp.93-100
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• 2014

The objective of this study is to propose the measurement system implementation method for the evaluation and measurement of the indoor-impulsive over 170 dB noise source. For the purpose of measuring impulse noise, design and implementation constructed followed subsystems of the testing center, microphone, ear simulator, head and torso simulator and so on. Measurement systems for the accuracy and reliability of impulse noise are implemented when measuring 3 ways of measurements method by the simultaneous measurement system design. For the accuracy and reliability of three mutually indoor-impulse noise measurements were compared, three kinds of measuring methods in accordance with the peak sound pressure level and octave band. Comparing the results of data, the indoor-impulse noise by analyzing a frequency characteristic was validated in difference for the statistical significance. Result are determined by the influence of the reflected wave. Therefore, the flexible size of the interior test site while interior impulse noise measurement system was constructed. Throughout this system can be affected by parameters that are the impulse noise source and the corresponding frequency-characteristic analysis to determine the spectrum of the reflected wave. And, in the near future, indoor impulse noise measurement systems for acquisition and analysis are utilized in useful data.

• Journal of the Korea Society of Computer and Information
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• v.19 no.5
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• pp.37-42
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• 2014

The objective of this study is the frequency of the noise source 170 dB level of impulsive sound attenuation performance by earplugs to identify, to analyze the frequency characteristics of a shape and pattern. The attenuation performance of the impulsive noise by the frequency levels on the Combat Arm and 3M Form types 1100 Earplugs were evaluated. In order to check the sound attenuation performance of the B&K head and torso simulator and sound attenuation performance of the ear simulator data was verified. Previous studies have most impact, even in the noise source and the impulse noise level is 140 dB, but this study is higher than that of the impulsive noise source features. The results of the impulse noise attenuation effect is frequency-dependent mean 28.58 dB.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06e
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• pp.15-18
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• 1998

지금까지의 입체음향 재생 연구에서는 Dummy head 나 Head and Torso Simulator(HATS)를 사용한 측정 HRTF(Head-Related Transfer Function)를 사용하여 입체음향 재생 시스템을 설계해왔다. 하지만 이러한 시스템은 구현의 단순함에도 불구하고 계산량 증가로 인한 실시간 구현의 어려움과, 신호처리로 인한 음색의 변화 및 음질의 저하, 정면 정위의 어려움 등 많은 문제점을 내포하고 있었다. 본 연구팀이 제안하는 Relative HRTF는 인체의 가하학적 모델링을 통한 구조적 접근 방법으로 이러한 단점을 극복할 수 있는 새로운 HRTF 모델링 기법이다. 이는 신호처리 과정의 단순화를 통하여 실시간 구현과 음색의 변화를 극소화시키고 스피커 구동 방식에서도 적절히 사용될 수 있다. 또한 본 연구를 위하여 기존의 HRTF 측정 방법의 문제점을 개선한 HATS를 이용한 Blocked Ear Canal HRTF 측정 방법에 대해서도 소개한다.

• International Journal of Highway Engineering
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• v.17 no.2
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• pp.89-98
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• 2015

PURPOSES : The objective of this study is to evaluate the performance properties of chip seals and fog seals with polymer-modified emulsions. METHODS : The performance of chip seals and fog seals was evaluated on the basis of common issues in surface treatments. Granite aggregate and four types of asphalt emulsions (one of the unmodified and three of the modified emulsions) were used considering the usage in field. A Vialit test was performed to determine the aggregate retention, and the MMLS3 (Third Scale Model Mobile Load Simulator) test was conducted to determine the aggregate retention, bleeding, and rutting. In addition, the fog seal specimens were tested by the BPT (British Pendulum Test) to evaluate skid resistance. RESULTS AND CONCLUSIONS : Overall, the polymer-modified emulsions (PMEs) showed better aggregate retention and bleeding resistance for both chip seals and fog seals. When comparing the performance of the PMEs, the difference was not considerable. In addition, PMEs present significantly better rutting resistance than unmodified emulsions. For skid resistance, if the recommended mix design is applied, the specimens do not cause issues with skid resistance. Although all of the fog seal specimens were over the criteria for skid resistance, the specimen fabricated by the high emulsion application rate (EAR) of the unmodified emulsion was nearly equivalent to the skid value criteria. Therefore, the use of an unmodified emulsion with a high EAR should be carefully applied in the field.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.3
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• pp.199-207
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• 2002

In this paper, a self-tuning gain-scheduled skyhook control for semi-active suspension systems is investigated. The dynamic characteristics of a continuously variable damper including electro-hydraulic pressure control valves is analyzed. A 2-d.o.f. time-varying quarter-car model that permits variations in sprung mass and suspension spring coefficient is considered. The self-tuning skyhook control algorithm proposed in this paper requires only the measurement of body acceleration. The absolute velocity of the sprung mass and the relative velocity of the suspension deflection are estimated by using integral filters. The skyhook gains are gain-scheduled in such a way that the body acceleration and the dynamic tire force are optimized. An ECU prototype is discussed. Experimental results using a 1/4-ear simulator are discussed. Also, a suspension ECU prototype targeting real implementation is provided.