• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.05a
• /
• pp.797-801
• /
• 2003

The Statistical Energy Analysis is based on the power flow and the energy conservation between sub-systems, which enable the prediction of acoustic and structural vibration behavior in mid-high frequency ranges. This paper discusses the identification of SEA coupling loss factor parameters from experimental measurements of small reverberation chamber sound pressure levels and structural accelerations. As structural subsystems, steel plates with and without damping treatment are considered. Calculated CLFs were verified by both transmission loss values for air-borne CLF case and running SEA commercial software As a result, CLFs have shown a good agreement with those computed by software. Acoustical behavior of air-borne noise and structure-borne noise has been examined. which shows reasonable results, too.

• Journal of the Ergonomics Society of Korea
• /
• v.24 no.1
• /
• pp.47-53
• /
• 2005

The purpose of this study was to evaluate performance and subjective satisfaction of mobile phone's interface elements considering the elderly users. First, mobile phone's interface elements were outlined recent foreign and domestic studies. Then, final three mobile phone's interface elements were determined by expert rating, AHP analysis, and questionnaire analysis. Objective and subjective measures were then used to determine the effects of several specific design parameters and aging differences on performance of mobile phones. In this experiment, 38 subjects and 4 independent variables were used to measure task completion time and user's subjective satisfaction. The statistical analyses indicated significant aging differences between older people and younger people in terms of keypad type and bell sound level in performance. Significant aging differences were also found for user subjective satisfaction. It is suggested that some major results from this study be used to develop mobile phone design guidelines that are more usable and accessible for most users, particularly for older users.

• Proceedings of the IEEK Conference
• /
• 2006.06a
• /
• pp.863-864
• /
• 2006

The aim of this study is to acquire useful information of lower urinary tract symptom(LUTS) diagnosis through urophonogaphy signal as noninvasive method. The system was implemented to measure urophonography signal, urinary volume and uroflow. The slope of the log-log plot of power spectrum density changed rapidly from $2.01{\sim}2.07$ to over 3.32 when the occlusion rate was 2 mm to 3.8 mm. This information combined with the uroflow parameters could give a useful prediction of lower urinary tract symptoms.

• International Journal of Railway
• /
• v.7 no.4
• /
• pp.109-116
• /
• 2014

For optimization of a low-noise track system, rail vibration and noise radiation needs to be investigated. The main influencing parameters for the noise radiation and the quantitative results of every track system can be obtained using a calculation model of generation and radiation of railway noise. This kind of model includes contact modeling and the calculation model of the dynamic properties of the wheel and the rail. This study used a nonlinear wheel/rail interaction model in the time domain to investigate the excitation of the rolling noise. Wheel/rail response is determined by time integrating Green's function of the rail together with force impulses from the wheel/rail contact. This model and the results of the study can be used for supporting calculation with the conventional model by an addition of the contributions due to nonlinearities to the roughness spectrum.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.35S no.4
• /
• pp.118-127
• /
• 1998

In this paper, we propose a voice personality transformation method which makes one person's voice sound like another person's voice. In order to transform the voice personality, vocal tract transfer function is used as a transformation parameter. Comparing with previous methods, the proposed method can obtain high-quality transformed speech with low computational complexity. Conversion between the vocal tract transfer functions is implemented by a linear mapping based on soft clustering. In this process, mean LPC cepstrum coefficients and mean removed LPC cepstrum modeled by the low dimensional vector are used as transformation parameters. To evaluate the performance of the proposed method, mapping rules are generated from 61 Korean words uttered by two male and one female speakers. These rules are then applied to 9 sentences uttered by the same persons, and objective evaluation and subjective listening tests for the transformed speech are performed.

• Proceedings of the KIEE Conference
• /
• 2000.07d
• /
• pp.3004-3006
• /
• 2000

In this paper, we propose an optimal design method of Fuzzy-Neural Networks model with parallel structure for complex and nonlinear systems. The proposed model is consists of a multiple number of FNN connected in parallel. The proposed FNNs with parallel structure is based on Yamakawa's FNN and it uses simplified inference as fuzzy inference method and Error Back Propagation Algorithm as learning rules. We use a HCM clustering and GAs to identify the structure and the parameters of the proposed model. Also, a performance index with a weighting factor is presented to achieve a sound balance between approximation and generalization abilities of the model. To evaluate the performance of the proposed model. we use the time series data for gas furnace and the numerical data of nonlinear function.

• The Journal of the Acoustical Society of Korea
• /
• v.21 no.4
• /
• pp.146-146
• /
• 2002

We present a new technique for achieving source separation when given only a single channel recording. The main idea is based on exploiting the inherent time structure of sound sources by learning a priori sets of time-domain basis functions that encode the sources in a statistically efficient manner. We derive a learning algorithm using a maximum likelihood approach given the observed single channel data and sets of basis functions. For each time point we infer the source parameters and their contribution factors. This inference is possible due to the prior knowledge of the basis functions and the associated coefficient densities. A flexible model for density estimation allows accurate modeling of the observation, and our experimental results exhibit a high level of separation performance for simulated mixtures as well as real environment recordings employing mixtures of two different sources. We show separation results of two music signals as well as the separation of two voice signals.

• Korean Journal of Oriental Medicine
• /
• v.4 no.1 s.4
• /
• pp.139-148
• /
• 1998

Measurement of different skin parameters are widely used in the practices and researches of the modern acupuncture. The most important parameter is conductance or impedance. For measurement, some researchers used D.C. and others used A.C. It has been experimentally shown that the acupuncture points and meridian lines have the characteristics of high potential, low electrical resistance, high capacitance, spontaneous sound production, spontaneous light production, and high temperature. The Purpose of this study was to examine the effect of Hapkok(LI-4, 合谷) on experimental frequency characteristics in Hapkok. The result of data analyses indicated that significant differences arise at frequency under 100Hz. We propose that development of Meridian detecting system or Meridian diagnosis system should be done using frequency under 100Hz.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09a
• /
• pp.252-253
• /
• 2006

The fabrication of complex-shaped parts out of Co-Cr-Mo alloy and 316L stainless steel by three-dimensional printing (3DP) was studied using two grades of each alloy with average particle size of 20 and $75\;{\mu}m$, respectively. To produce sound specimens, the proper 3DP processing parameters were determined. The sintering behavior of the powders was characterized by dilatometric analysis and by batch sintering in argon atmosphere at $1280^{\circ}$ for 2h. The 3DP process has successfully produced complex-shaped biomedical parts with total porosity of 12-25% and homogenous pore structure, which could be suitable for tissue growth into the pores.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.21 no.7
• /
• pp.650-656
• /
• 2011

The noise inside a naval vessel is very important in considering the need for hearing protection, improving the working environment and maintaining good communications for crews living on board a naval vessel. The indoor noise of a ship usually is specified by the A-weighted sound pressure level, but other evaluating parameters are required to reflect human senses more effectively. This paper uses additional noise indices related to room acoustics, such as NR(noise rating), NC(noise criterion), RC(room criterion), PSIL(preferred speech interference level) and loudness level to evaluate the noise inside cabins on a naval vessel. Using these psychological noise indices, allowable limit of noise level in cabins is suggested through psycho-acoustic evaluation for the noise in cabins.