• The Journal of the Korea Contents Association
• /
• v.5 no.6
• /
• pp.74-86
• /
• 2005

In this paper, we proposed an algorithm for the approximation of high order FIR filters by low order IIR filters to efficient implementing two channel 3-D surround sound systems using Head-related transfer functions(HRTFs). The algorithm is based on a concept of the balanced model reduction. The binaural sounds using the approximated HRTFs are reproduced by headphone, and serves as a cue of sound image localization. HRTFs of dummy-head are approximated from 512-order FIR filters by 32-order IIR filters and compare with each other. .Experiment of sound image are carried out for 10 participants. We perform the experiment based on computer simulation and hardware experiment with TMS320C32. The results of the experiments show that the localization using the approximated HRTFs is the same accuracy as the case of FIR filters that simulate the HRTFs.

• The Journal of the Acoustical Society of Korea
• /
• v.27 no.7
• /
• pp.333-341
• /
• 2008

In this paper, a new interpolation model for the head related transfer function (HRTF) was proposed. In the method herein, we assume that the impulse response of the HRTF for each azimuth angle is given by linear interpolation of the time-delayed neighboring impulse responses of HRTFs. The time delay of the HRTF for each azimuth angle is given by sum of the sound wave propagation time from the ears to the sound source, which can be estimated by using azimuth angle, the physical shape of the underlying head and the distance between the head and sound source, and the refinement time yielding the minimum mean square error. Moreover, in the proposed model, the interpolation intervals were not fixed but varied, which were determined by minimizing the total number of HRTFs while the synthesized signals have no perceptual difference from the original signals in terms of sound location. To validate the usefulness of the proposed interpolation model, the proposed model was applied to the several HRTFs that were obtained from one dummy-head and three human heads. We used the HRTFs that have 5 degree azimuth angle resolution at 0 degree elevation (horizontal plane). The experimental results showed that using only $30\sim40%$ of the original HRTFs were sufficient for producing the signals that have no audible differences from the original ones in terms of sound location.

• Proceedings of the Korea Contents Association Conference
• /
• 2007.11a
• /
• pp.121-125
• /
• 2007

This paper proposes automatic generation method of proxy client code to automation of web service selection process through a monitoring agent. The technique of this paper help service consumer to provide source code of proxy client as it bring an attribute value of specific element of WSDL document using template rule. Namely, a XSLT script file provide code frame of dynamic invocation interface model. The automatic code generation technique need to solving starvation status of selection architecture. It is required to creating request HTTP message for every service on the result of search. The created proxy client program code generate dummy message about services. The proposed client code generation method show us a possibility of application in the automatic generation programming domain.

• The Journal of the Korea Contents Association
• /
• v.8 no.1
• /
• pp.228-235
• /
• 2008

This paper proposes automatic generation method of proxy client code to automation of web service selection process through a monitoring agent. The technique of this paper help service consumer to provide source code of proxy client as it bring an attribute value of specific element of WSDL document using template rule. Namely, a XSLT script file provide code frame of dynamic invocation interface model. The automatic code generation technique need to solving starvation status of selection architecture. It is required to creating request HTTP message for every service on the result of search. The created proxy client program code generate dummy message about services. The proposed client code generation method show us a possibility of application in the automatic generation programming domain.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.16 no.1
• /
• pp.89-95
• /
• 2016

In this paper, we propose a locker system that can remotely control and manage locker. The main features of the proposed system are follows. First, connect the locker with server and then open the locker after passing through the certification process in server. Second, locker manager can more systematically manage a locker by using locker management system based on smart phone. Third, provide an instant locker for temporary using lockers to increase the ease of use. Fourth, unlike traditional analog locker, can support better security by using authentication process and log data. Performance evaluation is performed via simulation by making the dummy model. The results of performance evaluation show the proposed system can support efficiently the locker management.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.38 no.4
• /
• pp.385-391
• /
• 2014

A wheeled armored vehicle is a military vehicle that has been developed to enhance combat capabilities and mobility for the army. The wheeled armored vehicle has a high center of gravity, and it operates on unpaved and sloped roads. Therefore, this vehicle has a high risk of rollover crashes. To design the interior of the military vehicle, the crew's safety during rollover crashes is an important factor. However, actual vehicle tests for design are extremely expensive. In this paper, nonlinear dynamic analysis is performed to simulate the rollover crashes and the passenger injury is assessed for a wheeled armored vehicle. The scope of this research is the rollover condition, FE modeling of the wheeled armored vehicle and the dummy, arrangement of dummies, assessment of passenger injuries, and simulation model for rollover crashes.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.2
• /
• pp.699-711
• /
• 2011

This study is to perform several major analyses to find any differences in the leverage between the pre- and post-period of the currency crisis. Moreover, another aspect is to investigate a financial aspect which has received relatively little attention to the firms and/or industries in the emerging capital markets in comparison to those in the advanced markets. The purpose of this empirical study is to confirm whether or not, it is myth or reality that Korean business conglomerate, chaebol, firms with subsidized financing from government-owned domestic financial institutions in the pre-financial turmoil, may still maintain their higher leverage, even after the crisis. It was found that firms belonging to the chaebol in Korea maintained higher average book-value and market-value based debt ratios, relative to their counterparts not belonging to the chaebol across all of the tested models. There were positive relationships of IND3(=the chemical industry) and Ind5(=the construction industry) to the book-value leverage. This study identified that there were no differences in the explanatory variables included, between the tested models (that is, without and with including the present value of an operating lease) related to each debt ratio. Since the Korean government continue to improve the corporate governance of the domestic firms in terms of accounting transparency and corporate ownership, it would be more efficient, if utilizing this "new" ratio considering an operating lease as an effective measurement of the level of leverage. In terms of the capital structure, it may also be possible for foreign firms to utilize and benefit from the results obtained in this study when operating their new businesses in Korea, given the economic circumstances such as the ongoing progress of the Korea-America FTA or the Korea-China FTA.

• Journal of Soil and Groundwater Environment
• /
• v.12 no.4
• /
• pp.1-7
• /
• 2007

Slug/bail tests were conducted in sand layer (sbt-1 well), silty sand layer (sbt-2 well), and mixed sand and silty sand layer (sbt-3 well). Hydraulic conductivity and specific storage coefficient were estimated through slug/bail tests. Pore volumes of groundwater level drawdown zone for bail test were estimated by using hydraulic conductivity and specific storage coefficient. KGS model was most suitable interpretation method of slug/bail tests. Average hydraulic conductivity for slug/bail tests were estimated to be $6.65{\times}10^{-5}$ m/sec in sbt-1 well, $6.33{\times}10^{-6}$ m/sec in sbt-2 well, and $3.72{\times}10^{-5}$ m/sec in sbt-3 well. Average specific storage coefficient for slug/bail tests were estimated to be 0.0225 in sbt-1 well, 0.0177 in sbt-2 well, and 0.0259 in sbt-3 well. Dimensionless time and dimensionless wellbore storage were estimated by use of transmissivity, storativity, test time, and specification of test wells. And, dimensionless drawdown were selected by parameter ${\alpha}\;and\;{\beta}$ parameter from Cooper et al. (1967). Radius of influence were estimated by estimated dimensionless time, dimensionless wellbore storage, and dimensionless drawdown. The average radius of influnce for slug/bail tests were estimated to be 1.377 m in sbt-1 well, 1.253 m in sbt-2 well, and 1.558 m in sbt-3 well. Pore volume at groundwater level drawdown zone by dummy withdrawal for bail tests were estimated to be $145,636cm^3$ in sbt-1 well, $71,561cm^3$ in sbt-2 well, and $100,418cm^3$ in sbt-3 well. Pore volume excepted well volume at groundwater level drawdown zone by dummy withdrawal for bail tests were estimated to be $145,410cm^3$ in sbt-1 well, $71,353cm^3$ in sbt-2 well, and $100,192cm^3$ in sbt-3 well.