• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1C
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• pp.130-137
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• 2010

An uplink indoor positioning system is proposed in the present work, where the acoustic signals are solely used for positioning. The underlying acoustic signals include whistle, finger snap, and hands-clapping. In the proposed method, positioning is achieved by finding the time-difference-of-arrivals using several self-generating sounds. To evaluate the feasibility of the signals and their positioning accuracies, the database of 100 persons about self-generating acoustic signals is built up. The results show that the hands-clapping sound is the most suitable for acoustic-based indoor positioning.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.4
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• pp.779-784
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• 2020

In this paper, we improved the high frequency noise characteristics of the previously proposed hearing aid circuits for presbycusis, and we designed and fabricated a stereo hearing aid module. The cause of high frequency noise, which occurs in some cases in the previous circuits under high gain conditions, was analyzed through simulations. Two mute switches were added to adjust each boosting gain for right and left ears more accurately by muting the sound of the other ear when adjusting the gain of one ear in the stereo hearing aid module.

• Journal of Mechanical Science and Technology
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• v.20 no.10
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• pp.1653-1661
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• 2006

AC induction motors have been widely used for fan motor of the air conditioner indoor unit. Noise of these AC induction motors is usually caused by the coupling effects of structural and electrical systems. The rotating torque and the noise from AC induction motor were discussed in this paper,. First, the modification of motor was carried out in order to reduce the unbalance magneto motive force between main and sub winding. Second, structural modification based on normal mode analysis and modal testing was carried out so that the fan motor does not have the natural frequencies near the 2f-line frequency. Numerical modifications through these two processes were verified by experiments, which showed that the sound pressure level at 2f-line frequency of the modified system became about 25dB less than that of conventional one.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.3
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• pp.602-608
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• 2014

Smartphones have become commonplace to use smart, BYOD (Bring Your Own Device) spread the trend of domestic WLAN use is intensifying as a result, the security threat will be greatly increased. Even though WLAN vendors such as Cisco Systems Inc,. Aruba networks released WIPS, MDM, DLP etc, however, these solutions can not be easily introduced for small business due to high cost or administrative reasons. In this paper, without the introduction of expensive H/W equipment, in WLAN environments, packet analysis, AP, Station management, security vulnerabilities can be analyzed by the proposed intrusion detection system.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2627-2629
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• 2003

In this paper, we propose a new architecture of Genetic Algorithms(GAs)-based Self-Organizing Polynomial Neural Networks(SOPNN). The conventional SOPNN is based on the extended Group Method of Data Handling(GMDH) method and utilized the polynomial order (viz. linear, quadratic, and modified quadratic) as well as the number of node inputs fixed (selected in advance by designer) at Polynomial Neurons (or nodes) located in each layer through a growth process of the network. Moreover it does not guarantee that the SOPNN generated through learning has the optimal network architecture. But the proposed GA-based SOPNN enable the architecture to be a structurally more optimized networks, and to be much more flexible and preferable neural network than the conventional SOPNN. An aggregate performance index with a weighting factor is proposed in order to achieve a sound balance between approximation and generalization (predictive) abilities of the model. To evaluate the performance of the GA-based SOPNN, the model is experimented with using nonlinear system data.

• Journal of the Korean Institute of Landscape Architecture
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• v.26 no.3
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• pp.19-33
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• 1998

The primary objective of this research was to develop optimal models for masking the road traffic noise with the sound of a waterfall at urban small green spaces. Noise levels were measured at 8 roadside green spaces in SEOUL and questionnaires were randomly distributed to 40 users for evaluating the noise at each site at the same time. College students participated in the experiment for the development of masking models and the developed models were tested by users at 2 green spaces. The major results are as follows ; 1. Traffic noises ranged from 65dBto 70 dB. Users' satisfaction with the noise became considerably low on the basis of 60 dB and it was highly related to noise level. 2. Noise was a main factor to depreciate the amenity of green spaces where its level was more than 60 dB and so it neds to be excluded or reduced the traffic noise at the process of design. 3. Masking effects kept constant independent of the spatial location of masker on condition that masker levels were equal. It was effective when masker was 5-10dB greater than noise level which was masked. 4. As noise level went up, satisfaction ratings about the masked noise became low but masking effects increased in proportion to its level. 5. It was proved that the models were valid through the field experiment.

• The KIPS Transactions:PartC
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• v.9C no.2
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• pp.157-162
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• 2002

In this study, the secure Internet phone system using digital signature and data encryption with DES algorithm and EDE algorithm was implemented. And new key distribution algorithm was suggested utilizing the Diffie-bellman algorithm. For reducing processing time, a table combined with S-BOX and P-BOX of the DES was used. The proposed system was implemented with Java and the results showed the processing time using DES algorithm for encryption was 1.46 seconds and that of EDE algorithm was 3.25 seconds respectively. This system can be applied to Protect the copyright of sound products and data using internet.

• Tribology and Lubricants
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• v.32 no.6
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• pp.207-211
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• 2016

To interpret the perception that originates from tactile sensibility during people touch and recognize the object surfaces, this study focuses on the development of a friction model that can describe the interaction of a stylus pen sliding over the counter surfaces. In addition, the study includes several other experimental factors such as the pressure, temperature, and topology of surface, which can have an effect on the emotional user experience concerning various surfaces; this research aims to suggest a method to quantitatively evaluate the relation between these experimental parameters and emotional user experience. Accordingly, the objective of research comprises the friction characteristic technology for measurement of fine tribological behavior and a standard to quantify the emotional feedback. Existing panels or input devices that provide interaction feedback about user actions simply operate with a single frequency vibration or sound response. On the contrary, this research investigates various interaction characteristics including friction force, frequency, and surface topology synthetically. Using the developed model, which can explain the relation between the friction parameters and emotional user experience, developers can design their product in order to provide the user with expected emotional sensibility. Consequently, it can contribute to reduce the development cost about sensitivity model.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.676-681
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• 2001

We usually divide the noise of exhaust system into pulsation noise and flow noise. Pulsation noise is the shock wave to occur when the burning gas of low pressure emits and include harmonic having basic frequency as the exhaust cycle of engine. Flow noise is the noise that is produced when gas flow emits into the atmosphere through the pipe and has the character of frequency like pink noise which has the high level of high frequency component. A muffler is divided into reflective type and absorptive type. We usually use the muffler compounding the property of them. In this study, it is the case of transfer matrix method that a muffler is compounded to analyze the elements of each section according to sound wave's proceed direction. But we use simple model. So, we use finite element method that takes short time to analyze. Acoustic analysis gives us transfer matrix to use FEA of SYSNOISE and we use STAR-CD for fluid analysis. We made database that is based on analytical results about the muffler of expansion type, extended type, offset type, reverse type, and perforated type and developed the muffler design system to perform work efficiently.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.924-927
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• 2009

IP reuse technology, for the sake of out-performance and the reduction of development period of IT-SoC is the most essential factor for the sound growth of SoC industry. As for this IP reuse technology, it is very important to decide the proper specification and the standardization of the requirement from the companies, as well as to develop our own domestic technological know-how which does not depend on import. In this study, we propose to analyze a security core IP with pure domestic technological know-how, mentioning an example from $CAST_{TM}$, which presently is an American company costing royalty.