• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.258-264
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• 2012

The overall aim of this paper is to determine coupling loss factor of welding point between shell and cylinder using loss factor and structural loss factor. For this purpose, two kinds of loss factor were adopted. One is loss factor of each sub structure, another is structural loss factor based on the complex welded or assembled structure. Using these two parameters, it is possible to derive the coupling loss factor which represents characteristic condition of SEA theory. Coupling loss factor of conjunction in complex structure was expressed as power balance equation. The derived equation for a coupling loss factor has been simplified on the assumption of one way (uni-directional) power flow between multi-sub structures. Using these conditions, it is possible to find the equation of coupling loss factor expressed as above two loss factors. To check the effectiveness of above equation, this paper used two-stage application. The first approach was application between simple cylinder and shell. The next was adopted rotary compressor. Rotary compressor has three main conjunctions between shell and internal vibration part. This equation was applied to find out the optimum welding point with respect to reduce the noise propagation. It shows the effective tool to evaluate the coupling loss factor in complex structure.

• Earthquakes and Structures
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• v.19 no.4
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• pp.243-259
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• 2020

This study aims to optimize, design, and predict the MTMDs performance in SDOF systems using spectral analysis, and then apply their results to MDOF structures. Given the importance of spectral analysis in the design of new engineering structures, achieving a method for designing TMDs based on this theory can be of great importance for structural designers. In this study, several convenient combinations of MTMDs in an SDOF system are first considered to minimize the maximum displacement. For calculating the frequency ratios of dampers, an innovative technique is adopted in which the values of different modal responses obtained from the spectral analysis are approached together. This procedure is done using a harmony search (HS) algorithm. Also, using the random vibration theory, the damping ratio of the dampers is obtained. Then, an equation is presented for predicting the performance of MTMDs. For evaluating this equation, three structures with different stories are designed. Some of the presented combinations of dampers are added to them. The time history analyses are employed to analyze the structures under 30 different accelerograms. The findings indicated that the proposed equation could efficiently predict the performance of the MTMDs. Furthermore, four different patterns of damper distribution along the height of the structures are defined. The effect of them on the maximum deformation of the structures in time history analyses is discussed, and an equation is presented to estimate this effect. The results indicated that the average and maximum error percentages of the proposed equations are about three and seven percent, respectively, compared to the time history analyses results, which are negligible values.

• Journal of The Korean Association For Science Education
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• v.35 no.2
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• pp.231-245
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• 2015

Flipped learning can be used as an innovative teaching method in science education. This study analyzes video clip produced by pre-service elementary school teachers for flipped learning and explore strategies to organize effective visualization. The pre-service elementary school teachers focused on providing information on macroscopic natural phenomenon using concrete case selection strategy for earth science class. They used marker and spatial transformation elements effectively, but their efforts to link the elements to the experience of students were not sufficient. In addition, it was very rare to put the contents into simplified drawing or provide extreme cases to enhance the imagery of students. In addition, it is necessary to provide specific case of multi-modal and link the material to the experience of students closely through familiar cases or analogical model to establish an effective visual teaching material. It may also be needed to present simplified drawing for enhancing imagery and provide extreme cases to make students have an opportunity to infer a new situation.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.12 no.1
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• pp.79-88
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• 2014

We have developed a smart decontamination device for small-size radioactive scrap metal (SSRSM) necessarily generated from nuclear facilities. This is a multi-modal device such as rotation of magnetic field focusing on the region containing the abrasion pins placed around target and ultrasonic cleaner. Additionally, in order to increase the decontamination efficiency we have modified some configuration of the device so that it could work on them evenly and totally. With the Optimal operating for operation of the new device, we tried to decontaminate some various metal selected as a sample during 15 minutes sequentially using each method, magnetic and ultrasonic device. As a result, the range of decontamination factor has been highly increased to 18~56. After decontamination, all samples were found its activity less than background level.

• Cartoon and Animation Studies
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• s.41
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• pp.307-336
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• 2015

Virtual reality technology is one of the important technologies that will affect our life in many ways. This novel technology will draw new paradigm into the medical field due to its advantages in physical safety and environment that are fully controlled. Phobia treatment using VR technology has been implemented and its feasibility has been proved through a number of researches in many institutions. This study has observed the current progress of its technology environment and the trend of research. Also, This study has analyzed the results from domestic and international data. Analysis shows that other countries are ahead of korea in all aspects of the phobia treatment using virtual reality method. Although the authors limited the kinds of journals, the amount of quantity in international researches are two times more than domestics. Also, The researchers in other countries concentrate on the multi-modal studies. To use virtual reality in the phobia treatment, we need to understand the needs of the society members and the government has responsibility to support what the researchers need.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.3
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• pp.67-77
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• 2004

The recent research has been focused on fusion of audio and visual features for reliable speech recognition in noisy environments. In this paper, we propose a neural network based model of robust speech recognition by integrating audio, visual, and contextual information. Bimodal Neural Network(BMNN) is a multi-layer perception of 4 layers, each of which performs a certain level of abstraction of input features. In BMNN the third layer combines audio md visual features of speech to compensate loss of audio information caused by noise. In order to improve the accuracy of speech recognition in noisy environments, we also propose a post-processing based on contextual information which are sequential patterns of words spoken by a user. Our experimental results show that our model outperforms any single mode models. Particularly, when we use the contextual information, we can obtain over 90% recognition accuracy even in noisy environments, which is a significant improvement compared with the state of art in speech recognition. Our research demonstrates that diverse sources of information need to be integrated to improve the accuracy of speech recognition particularly in noisy environments.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.4 s.316
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• pp.36-44
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• 2007

In this paper, we implement the speech & face recognition system to support various ubiquitous sensor network application services such as switch control, authentication, etc. using wireless audio and image interface. The proposed system is consist of the H/W with audio and image sensor and S/W such as speech recognition algorithm using psychoacoustic model, face recognition algorithm using PCA (Principal Components Analysis) and LDPC (Low Density Parity Check). The proposed speech and face recognition systems are inserted in a HOST PC to use the sensor energy effectively. And improve the accuracy of speech and face recognition, we implement a FEC (Forward Error Correction) system Also, we optimized the simulation coefficient and test environment to effectively remove the wireless channel noises and correcting wireless channel errors. As a result, when the distance that between audio sensor and the source of voice is less then 1.5m FAR and FRR are 0.126% and 7.5% respectively. The face recognition algorithm step is limited 2 times, GAR and FAR are 98.5% and 0.036%.

• Structural Engineering and Mechanics
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• v.52 no.3
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• pp.485-505
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• 2014

This study aimed to develop an approach to accurately predict the wind models and wind effects of large wind turbines. The wind-induced vibration characteristics of a 5 MW tower-blade coupled wind turbine system have been investigated in this paper. First, the blade-tower integration model was established, which included blades, nacelle, tower and the base of the wind turbine system. The harmonic superposition method and modified blade element momentum theory were then applied to simulate the fluctuating wind field for the rotor blades and tower. Finally, wind-induced responses and equivalent static wind loads (ESWL) of the system were studied based on the modified consistent coupling method, which took into account coupling effects of resonant modes, cross terms of resonant and background responses. Furthermore, useful suggestions were proposed to instruct the wind resistance design of large wind turbines. Based on obtained results, it is shown from the obtained results that wind-induced responses and ESWL were characterized with complicated modal responses, multi-mode coupling effects, and multiple equivalent objectives. Compared with the background component, the resonant component made more contribution to wind-induced responses and equivalent static wind loads at the middle-upper part of the tower and blades, and cross terms between background and resonant components affected the total fluctuation responses, while the background responses were similar with the resonant responses at the bottom of tower.

• Journal of the Ergonomics Society of Korea
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• v.30 no.1
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• pp.195-202
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• 2011

Objective: The aim of this study is to investigate and review the previous researches about objective measuring fatigue caused by visual stimuli. Also, we analyze possibility of alternative visual fatigue measurement methods using facial expression recognition and gesture recognition. Background: In most previous researches, visual fatigue is commonly measured by survey or interview based subjective method. However, the subjective evaluation methods can be affected by individual feeling's variation or other kinds of stimuli. To solve these problems, signal and image processing based visual fatigue measurement methods have been widely researched. Method: To analyze the signal and image processing based methods, we categorized previous works into three groups such as bio-signal, brainwave, and eye image based methods. Also, the possibility of adopting facial expression or gesture recognition to measure visual fatigue is analyzed. Results: Bio-signal and brainwave based methods have problems because they can be degraded by not only visual stimuli but also the other kinds of external stimuli caused by other sense organs. In eye image based methods, using only single feature such as blink frequency or pupil size also has problem because the single feature can be easily degraded by other kinds of emotions. Conclusion: Multi-modal measurement method is required by fusing several features which are extracted from the bio-signal and image. Also, alternative method using facial expression or gesture recognition can be considered. Application: The objective visual fatigue measurement method can be applied into the fields of quantitative and comparative measurement of visual fatigue of next generation display devices in terms of human factor.

• International Journal of Advanced Culture Technology
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• v.8 no.2
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• pp.116-128
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• 2020

In this study, we introduce a multi-modal mixed reality (MR) application for advertising the main touristic landmarks on Jeju Island, and evaluate its effectiveness based on the Technology Acceptance Model (TAM) with a focus on the user's involvement in Korean culture (K-Culture). Specifically, we deployed several stimuli to enable users to retrieve information, visualize a variety of heritage content such as text, images, videos, virtual artifacts, and immerse in a VR environment to experience the heritage locations. The results of the online survey with 436 participants showed that for consumers with low K-Culture involvement, Perceived Usefulness and Perceived Ease-of-Use did not affect their Intention to Visit the island. Still, it had a significant impact on their Intention to Use the application. On the other hand, for the group with high K-Culture involvement, Perceived Usefulness had no effect on the Intention to Use and Intention to Visit. However, Perceived Ease-of-Use had a significant impact on their Intention to Use the application and Intention to Visit Jeju Island. Therefore, when user involvement in K-Culture is high, convenience of use has played a significant role in sensory media usage and the intention to visit, regardless of the usefulness of the mixed reality content. In contrast, users with low K-Culture involvement primarily focused on the functional aspects of the application. These findings open the path for follow-up studies on K-Culture involvement and immersive media tourism marketing, which will benefit digital tourism marketing and Korea's tourism industry.