• Journal of KIISE:Computing Practices and Letters
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• v.8 no.3
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• pp.344-355
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• 2002

Having a variety of good characteristics against other pattern recognition techniques, Multilayer Perceptron (MLP) has been used in wide applications. But, it is known that Error Backpropagation (EBP) algorithm which MLP uses in learning has a defect that requires relatively long leaning time. Because learning data in pattern recognition contain abundant redundancies, in order to increase learning speed it is very effective to use online-based teaming methods, which update parameters of MLP pattern by pattern. Typical online EBP algorithm applies fixed learning rate for each update of parameters. Though a large amount of speedup with online EBP can be obtained by choosing an appropriate fixed rate, fixing the rate leads to the problem that the algorithm cannot respond effectively to different leaning phases as the phases change and the learning pattern areas vary. To solve this problem, this paper defines learning as three phases and proposes a Instant Learning by Varying Rate and Skipping (ILVRS) method to reflect only necessary patterns when learning phases change. The basic concept of ILVRS is as follows. To discriminate and use necessary patterns which change as learning proceeds, (1) ILVRS uses a variable learning rate which is an error calculated from each pattern and is suppressed within a proper range, and (2) ILVRS bypasses unnecessary patterns in loaming phases. In this paper, an experimentation is conducted for speaker verification as an application of pattern recognition, and the results are presented to verify the performance of ILVRS.

• Cross-Cultural Studies
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• v.42
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• pp.261-283
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• 2016

The aim of this study is to consider the possibility of learning polite expressions of English using the mobile application Naver Band. To improve communicative competence, students need to develop sociolinguistic competence as well as grammatical and discourse competence. To be accordant to social context, the roles of the participants, and the purpose of the interaction, students have to make an appropriate utterance. When a hearer has a higher social status and is older than a speaker, or have low levels of familiarity, Korean native speaker tends to use polite expressions. Students need to learn polite expressions of English because English has a different honorific system from Korean. To realize the characteristics and function of polite language is one thing, but to learn it in a real classroom is another. This study attempts to apply the use of a mobile application, which is considered a user-friendly tool for students, into learning polite language using the UK historical drama, Downton Abbey. Two tests were administered to an experimental group that used the mobile application and a control group that used group work. The results of the two tests show that the use of the mobile application has a positive effect on learning polite expressions and is effective as an after-school activity. In an open-ended questionnaire, students tend to identify polite expressions as superior or high-level language forms and separate these forms from practical expressions. It should be noted as well that teachers need to consider instructing in modern English when using a historical drama in the teaching and learning of polite expressions.

• Knowledge Management Research
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• v.18 no.1
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• pp.83-116
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• 2017

The purpose of this study is to analyze empirically analyze how the characteristics of participants in educational and social learning forums and the quality of events influence expectations and satisfaction of forums. The study also aims to provide strategic implications for forum organizers and give them suggestions on how to set up target audience, manage forum contents, speakers, and services, improve attendee satisfaction, and ultimately maximize overall outcomes. As exchanges among individuals, enterprises, and organizations, as well as countries are growing rapidly, the convention industry has become a key player in the market. Conventions have also become a venue for people to discuss a specific agenda or topic, exchange information and learn knowledge and insights. Especially, the forum - as part of the convention industry - plays a vital role providing educational and social learning opportunities as scholars and expertise come together to share their knowledge and experience through a variety of discussions. With its role, many of forums are taking place in recent years; however, there have been few empirical studies upon the forum itself. Also, there have been few attempts to research how the quality of forums affect participants' satisfaction along with their characteristics and how much of practical knowledge is provided throughout the events. This study is meaningful in that it is the first practical study that takes a deep understanding of the forum and sees how the quality of the forums influences participants' satisfaction and whether the characteristics of participants have a moderating effect in increasing the level of satisfaction. Forum organizers could also take a strategic approach as their major concerns are to increase the number of participants and raise degree of satisfaction by providing significant information. There are four key elements that determine success or failure of a social learning forum. The four elements are contents, speakers, services, and participants. Content plays an important role in providing rich information and knowledge for participants. Speakers are the main knowledge providers who contribute to the forum's social learning role. Also, the services provided by forum organizers such as simultaneous interpretation services, program brochures, lunch and refreshments, and the overall design of event hall can also influence the level of participants' satisfaction. Lastly, the participants and their characteristics are important since they are the ones who receive knowledge from the providers. The results of this study show that the quality of forum (content, speaker, and services) has a decisive effect on the participants' satisfaction and there are some differences in expectation among the participants in the forum. Also, some groups of participants were more likely to be stimulated by the quality of forum when determining their satisfaction. The study is modeled after MBN Y Forum 2016 and its participants' characteristics. The forum is one of the most representative social learning forums of South Korea and its audiences are mostly young people. It has analyzed how the participants' characteristics influence their satisfaction by grouping them into ${\Delta}participants$ who have invited for free and those who paid for the entrance fee, ${\Delta}first-time$ participants and returning participants, ${\Delta}voluntary$ and involuntary participants, ${\Delta}participants$ who registered through web and those who did through mobile, and ${\Delta}participants$ who registered during pre-sale opens and those who registered during general opens.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.43 no.3
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• pp.206-211
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• 2007

The sciaenid species, which has swimbladder, generates sounds by vibrating in its length wards when spawning or getting stimulus from something else. This research analyzed on sound frequency characteristics relatives to their swimbladder length of three sciaenid species, yellow croaker(Larimichthys polyactis), brown croaker(Miichthys miiuy), and white flower croaker(Nibea albiflora). As results, the dominant frequency for yellow croaker ranged over 38.08 to 141.60Hz in wide frequency band, and the averaged pulse duration expressed in $280.3{\pm}156.0ms$. For brown croaker, the dominant frequency ranged in 49.80 to 59.57Hz, and the averaged pulse duration was $129.1{\pm}36.9ms$. Moreover, the dominant frequency of white flower croaker ranged in 73.24 to 86.91Hz, and the averaged pulse duration was $88.0{\pm}15.9ms$, it has shorter pulse duration than any two species. Therefore, the dominant frequency relatives to swimbladder length of sciaenidae showed that it had widely resonant characteristics and long pulse duration as in shorter swimbladder length. Additionally, for white flower croaker, we could confirm their behavior and sounds in response to production of recorded sounds using underwater speaker.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.3647-3653
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• 2010

An experimental investigation of the flame appearance and heat transfer characteristics in both unexcited and excited impinging inverse diffusion flames with a loud speaker has been performed. The flame is found to become broader and shorter (in length) with acoustic excitation. The heat flux at the stagnation point is increased with the acoustic excitation. The acoustic excitation is more effective in lean conditions than in rich conditions. The reasons for these behaviors are that acoustic excitation improves the entrainment of surrounding air into the jet. From this study, it is found that the maximum increase of 57% in the total heat flux is obtained at the stagnation point of $\Phi$=0.8. Therefore, it is ascertained that the excitation combustion can be adopted with effective instruments as a method for improving heat transfer in impinging jet flames.

• The Journal of the Acoustical Society of Korea
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• v.18 no.1
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• pp.78-85
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• 1999

In this paper we propose a method to improve the performance of the mel-cepstrum that is widely used in speech recognition. Typically, the met-cepstrum is obtained by critical band filters that have fixed center spacing and bandwidth. However different filter characteristics produce a different mel-cepstrum, resulting in a different performance. In this paper we analyze triangular-shaped and rectangular-shaped filters. By changing the characteristics of filters such as center frequency and bandwidth, we analyze the performance of the met-cepstrum. Then utilizing the simplex method, we propose a method to optimize the critical band filters. Using the dynamic time warping, we performed speaker independent recognition experiments with Korean digit words pronounced by 10 males and 10 females. Experiments show that the rectangular-shaped filters show good performance and the mel-cepstrum obtained by the optimized filters shows better performance than filters that have fixed center spacing and bandwidth.

• Design & Manufacturing
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• v.11 no.1
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• pp.1-6
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• 2017

In these days, due to generalization of using smart mobile phone and wearable device such as smart watch, demand of Cover-glass and touch screen panel for protecting display increases. With increasing the demand of Cover-glass, slimming technique is promising for weight lightening, zero bezel. Cover-glass produced by this technique is required to decreasing thickness with increase strength. In the Cover-glass manufacturing process, mechanical processing and chemical processing has improve in the strength. Generally, Diamond electrodeposition wheel is used in mechanical process. Reinforced glass with the characteristics of the brittle and high hardness was manufactured by using a diamond electrodeposition wheel. At this time, Because of surface of the tool present non-uniform distribution of diamond particle, it has generate Loading of wheel and it has been decrease life of grinding tool, efficiency of grinding, quality and shape accuracy of workpiece. Thus Research is needed to controling particle distribution of diamond electrodeposition wheel uniformly. And it is necessary to study micro hole machining such as proximity senser hole, speaker hole positioned Cover-glass. Reinforced glass with the characteristics of the brittle and high hardness is difficult to machining. Processing of reinforced glass have generated wear of tool, micro cracks. Also, it is decreasing shape accuracy. In this paper, We conducted a study on how to control particle distribution uniformly about the diamond tool manufactured using elecetodeposition processing. It analyzed the factors that affect the arrangement of the particles in the electrodeposition process by design of experiment. And There is produced the grinding tool, which derives an optimum deposition conditions, for processing Cover-glass edge and the machinability was evaluated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.5
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• pp.679-683
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• 2013

BSR noise emerges in a vehicle as a result of road vibrations, engine vibrations, and speaker vibrations. BSR noise occurs with an irregular impact or stick slip friction phenomenon as the influence of the resonance mode when the vibration input load is transferred along poor joint and contacting pairs of the system. A sub-structure method of finite element analysis is required to detect impacts and slip in the full vehicle model. This study presents a method for sub-structure modeling and a rattle and squeak detection methodology that considers the characteristics of road vibration inputs.

• Journal of Sensor Science and Technology
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• v.21 no.2
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• pp.144-150
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• 2012

A microphone for fully implantable hearing device was generally implanted under the skin of the temporal bone. So, the implanted microphone's characteristics can be affected by the accompanying noise due to masticatory movement. In this paper, the implantable microphone with 2-channels structure was designed for reduction of the generated noise signal by masticatory movement. And an experimental model for generation of the noise by masticatory movement was developed with considering the characteristics of human temporal bone and skin. Using the model, the speech signal by a speaker and the artificial noise by a vibrator were supplied simultaneously into the experimental model, the electrical signals were measured at the proposed microphone. The collected signals were processed using a general adaptive filter with least mean square(LMS) algorithm. To confirm performance of the proposed methods, the correlation coefficient and the signal to noise ratio(SNR) before and after the signal processing were calculated. Finally, the results were compared each other.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.5
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• pp.471-479
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• 2022

Recently, piezoelectric devices, such as ultrasonic surgery, ultrasonic atomizer, and ultrasonic speaker, are analyzed and designed by finite element simulation methods. However, the discrepancy between the design and the experiment results of the device typically occurs due to the inaccuracy of the piezoelectric material properties. To improve the simulation accuracy, the material properties of the PZT ceramics were better refined using parameter estimation method. The material parameters are elastic stiffness c^E_ij and piezoelectric constant e_ij of PZT ceramics. The impedance curve characteristics for the LTE mode of PZT ceramics were calculated. The mismatch between the simulation and the experimental data were compared and minimized by a least square method. Finally, the simulated impedance data were compared with the experimental data for the various vibration modes of PZT ceramics and the optimized material properties of PZT ceramics were verified. To further verify the accuracy, this method was also applied to piezoelectric PMN-PT single crystals.