• The Journal of the Acoustical Society of Korea
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• v.26 no.6
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• pp.276-285
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• 2007

In this paper it was discussed and compared measured loudspeaker impedance curve with ones reconstructed by TS parameters estimated using four kinds of parameter estimation methods developed in frequency domain. Frequency dependent parameters were introduced and derived using least square error minimization technique. For known dynamic mass TS parameter estimation methods were reviewed and also proved non-uniqueness of these parameters by simulation method. Minimum phase transformation was adopted to derive phase information from magnitude of loudspeaker electrical impedance curve measured by one channel analyzer.

• Journal of Practical Engineering Education
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• v.14 no.2
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• pp.367-376
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• 2022

In this study, the user experience was analyzed from the learner's point of view, focusing on the metaverse platform 'Spatial'. SUS(System Usability Scale) was used to evaluate the usability of the metaverse platform 'Spatial' in a college class, and the Magnitude estimation technique was used to evaluate the immersion and satisfaction with the class. In addition, a questionnaire survey was used to collect user experience opinions on the use of 'Spatial' as a teaching tool. Looking at the usability evaluation results of the 'Spatial' system, the students evaluated the usability, immersion, and satisfaction quite positively. Looking at the user experience of metaverse platform 'Spatial', it was found that students highly valued Metaverse as an educational tool that can provide a place for many people to gather and communicate even in a non-face-to-face space. Compared to other online platforms, metaverse has advantages in ease of use, interaction, immersion, and interest. In particular, in addition to keyboard, touch, and display, interaction using the five senses such as voice, motion, and gaze was recognized as a great advantage. On the other hand, it was found that high openness, freedom, and interest factors can both promote learning and inhibit learning. Nevertheless, it is judged that the metaverse platform 'Spatial' can be effectively applied in college classes because it enables various interactions between instructor and learner or between learner and learner.

• Journal of the Earthquake Engineering Society of Korea
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• v.1 no.1
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• pp.69-77
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• 1997

An intensity survey on the 13 December 1996 Yeogweol earthquake has mode for 262 locations throughout southern part of Korean peninsula, then we investigated attenuation properties in the south Korean region as well as intensities distribution. In this study, intensities are estimated to be from II to possibly VIII. The iso-seismal intensity map we obtained shows general pattern of intensity distribution in the south korean region quite clearly despite the inherent uncertainties included in the process of intensity estimation. In case of intensity larger than VI, considerable damages such as fracturing walls are frequently reported. One of the significant feature of this intensity map is, considering its magnitude 4.5 reported by KMA, the felt area is unusually large covering most of the Korean Peninsular except Cheju island. This result indicates either the magnitude is under estimated or the focal depth is much deeper than expected. Assuming indicates either the magnitude is under estimated or the focal depth is much deeper than expected. Assuming shallow earthquake whose focal depth is by iso-seismal contour lines for intensity IV to VII, respectively. To resolve this ambiguity, more reliable estimation of focal depth and magnitude by using telesesmic instrumental records should be made in the future.

• Journal of the Korea Society for Simulation
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• v.24 no.3
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• pp.45-54
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• 2015

This paper presents the influence of backlash can be greatly increased on the frequency response characteristic which is presented as the angular velocity of a motor to the motor input voltage, if the motor input voltage is adequately reduced. And, this paper verifies theoretically, analytically and experimentally the availability on the method of detecting the change of backlash magnitude by investigating on the change of the anti-resonance and resonance frequencies in the frequency response characteristic due to the change of backlash magnitude. The amount of change of anti-resonance frequency is more useful that of resonance frequency when detecting the change of backlash magnitude, because the change of anti-resonance frequency can be measured more stable. This paper also shows the sharp change of resonance frequency can be investigated when the motor input voltage is enough reduced. The work will be useful for the further research on the backlash estimation method of a servo system with a gear reducer.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1671-1674
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• 1997

In tihs paper, an acceleratiion transformation algorithm which compensates the sculling error is proposed for strapdown inertial navigation system. The algorithm utilize the corss-product of the acceleromenter outputs and gyro outputs to keep the accuracy of the vehicle velocity under high frequency dynamic motion. From the error analysis of the algorithm, it is shown that the magnitude of estimation error is reduced by four orders.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.665-669
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• 1997

In this study, the fatigue lives of two kinds of specimens made by co/sab 2/ gas were assessed. The materials for two kinds of specimens were taken out of the virgin carbon steel tubes and used carbon steel tubes, respectively. As a result, it was found that the fatigue lives of two groups of specimens were in the same order of magnitude.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.357.2-357
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• 2002

The blast vibration can generate occupants dissatisfy as well as damage of physics nearby building. Then blast vibration estimation issue important problems. But, now blast vibration prediction inside-outside country not established objective method according to blast number to express magnitude of vibration. In this study, Our propoes show our country problem of blast vibration about blast vibration measurement and this problems be able to find improve method. (omitted)

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.517-520
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• 1999

In this paper, we propose a non-invasive method to estimate blood velocity from the real medical images. To measure the magnitude and direction components associated with the blood velocity, we apply the optical flow analysis algorithm. It is demonstrated that the accuracy of the blood velocity estimate could possibly be increased by segmenting the optical flow region. We call this the Region Optical Flow(ROF) algorithm. We carried out some preliminary experiments using the aorta medical images, and corresponding regional optical flow diagrams are provided.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.1
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• pp.13-18
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• 1998

In this study. the fatigue lives of two kinds of specimens made by $CO^2$ gas weld were assessed. The materials for two kinds of specimens were taken out of the virgin carbon steel tubes and the used carbon steel tubes respectively. As a result, it was found that the fatigue lives of two groups of specimens were in the same order of magnitude.

• Journal of the Korean Data and Information Science Society
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• v.15 no.4
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• pp.965-971
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• 2004

In this paper we consider several nonparametric estimators for the mean residual life by using the partial moment approximation under the proportional hazard model. Also we compare the magnitude of mean square error of the proposed nonparametric estimators for mean residual life under the proportional hazard model.