• Journal of the Korean Institute of Intelligent Systems
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• 제11권4호
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• pp.354-358
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• 2001

This paper presents a fuzzy neural network model which solves the underutilization problem. This fuzzy neural network has both stability and flexibility because it uses the control structure similar to AHT(Adaptive Resonance Theory)-l neural network. And this fuzzy nenral network does not need to initialize weights and is less sensitive to noise than ART-l neural network is. The learning rule of this fuzzy neural network is the modified and fuzzified version of Kohonen learning rule and is based on the fuzzification of leaky competitive leaming and the fuzzification of conditional probability. The similarity measure of vigilance test, which is performed after selecting a winner among output neurons, is the relative distance. This relative distance considers Euclidean distance and the relative location between a datum and the prototypes of clusters. To compare the performance of the proposed fuzzy neural network with that of Kohonen Self-Organizing Feature Map the IRIS data and Gaussian-distributed data are used.

• Journal of Advanced Navigation Technology
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• 제20권4호
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• pp.298-304
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• 2016

In this paper, a wavelet packet transform method is proposed for improving the altitude control performance of quadrotor UAV using an ultrasonic rangefinder. A ground tests are conducted using an ultrasonic rangefinder that is much used for vertical takeoff and landing. An ultrasonic rangefinder suffers from signal's spike due to specular reflectance and acoustic noise. The occurred spikes in short time span need to be analyzed at both sides time and frequency domain. The analyzed spikes of the ultrasonic rangefinder using a wavelet packet transform. Compared with the discrete wavelet transform, the wavelet packet decomposition can obtain more abundant time-frequency localization information, so it is more suitable for analyzing and processing ultrasonic signals spike. Experimental results show that it can effectively remove the spikes of the ultrasonic rangefinder.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• 제46권2호
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• pp.182-188
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• 2018

In order to increase the robustness of the uplink for UAS(Unmanned Aerial System), we propose a jamming signal rejection algorithm. In the UAS datalink system, DSSS (direct sequence spread spectrum) is used to reduce the radio noise or jamming signal. In general, jamming signals below the spreading gain are recoverable but the signals beyond the spreading gain can not be recovered. In this paper, these jamming signals beyond spreading gain are detected using the threshold detector in the spectrum area then, generate the estimated signals from the sine wave generator. Finally, we obtain the desired signal to remove jamming signals from the received signals. The proposed scheme can eliminate jamming signals while minimizing the hardware complexity and the original signal loss.

• The Journal of the Korea Contents Association
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• 제17권3호
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• pp.421-430
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• 2017

In this paper, research results on the change of music emotion are described. Our gaol was to provide a method of changing music emotion by a human user. Then we tried to find a way of transforming the contents of the original music into the music whose emotion is similar with the changed emotion. For the purpose, a method of changing the emotion of playing music on two-dimensional plan was describe. Then the original music should be transformed into the music which emotion would be equal to the changed emotion. As the first step a method of deciding which music factors and how much should be changed was presented. Finally the experimental method of editing by sound editor for changing the emotion was described. There are so many research results on the recognition of music emotion. But the try of changing the music emotion is very rare. So this paper would open another way of doing research on music emotion field.

• Journal of Korean Society of Environmental Engineers
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• 제29권8호
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• pp.944-949
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• 2007

The profiles of on-line sensors such as DO, ORP and pH can provide useful information about pollutant removal reaction in sequencing batch reactor. For detection of denitrification completion, the nitrate hee point from ORP profile has been considered as a main indicator of denitrification completion. However, many researchers pointed out that the nitrate knee usually disappeared been the progress of denitrification is so fast and it makes the fault at detection of denitrification completion. In this paper, dynamic time warping(DTW) method and discriminant analysis were used to detect and isolate the profiles of two cases, denitrification completed and uncompleted. As the results, proposed methods can detect state of denitrification successfully.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• 제10권2호
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• pp.63-70
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• 1996

In this paper, we propose the low sldelobe digital doppler filter bank design algorithm which is practically applicable to coherent radar equipment in complex air-defense system. Using the proposed algorithm, we can obtain a digital doppler filter bank of lower peak sidelobe level and higher clutter suppression capability. In this method, it is possible to achieve higher target-detectability without loss of Target SNR. The proposed algorithms are verified by simulations and experiments.

• Journal of Satellite, Information and Communications
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• 제11권4호
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• pp.58-62
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• 2016

In this paper, we propose a pre-processing scheme for improving indoor positioning accuracy in impulsive noise channel environments. The impulsive noise can be generated by multi-path fading effects by complicated indoor structures or interference environments, which causes an increase in demodulation error probability. The proposed pre-processing scheme is performed before a triangulation method to calculate user's position, and providing reliable input data demodulated from a received signal to the triangulation method. Therefore, we studied and proposed an adaptive threshold function for mitigation of the impulsive noise based on wavelet denoising. Through results of computer simulations for the proposed scheme, we confirmed that Bit Error Rate and Signal-to-Noise Ratio performance is improved compared to conventional schemes.

• Journal of the Institute of Electronics and Information Engineers
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• 제51권5호
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• pp.99-105
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• 2014

A reference spur suppressed PLL with two-symmetrical loops without changing the bandwidth which is optimized to suppress phase noise and reduce locking time has been designed. The principle of suppressing a reference signal spur is to stabilize the input voltage of voltage controlled oscillator (VCO). The proposed PLL consists of a phase-frequency detector(PFD) which has two outputs, two charge pumps(CP), two loop filters(LF), a divider and a VCO which has two inputs. Simulation results with $0.18{\mu}m$ CMOS process show that the reference spur is approximately suppressed to 1/2 of the reference spur in a conventional PLL. Even though there is a 5% process variation in the magnitude of R and C, the simulation result shows that the reference spur is still suppressed to 1/2 of the reference spur in a conventional PLL. The power consumption is 6.3mW at the power supply of 1.8V.

• Information and Communications Magazine
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• 제15권7호
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• pp.75-94
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• 1998

In this paper, HFC CATV networks are introduced. HFC CATV networks are currently considered as a most effective and plausible solution for subscriber access networks in the information superhighway, among others such as ADSL and B-WLL. The advantages of HFC CATV networks include its broad upstream and downstream channel bandwidths, much wider than PSTN's and its readiness. The HFC CATV networks are already well spread among the general subscribers in Korea. This fact will shorten the installation period and significantly reduce its cost. In addition, The structure and channel environment of the HFC CATV networks are introduced. At the same time, in this paper included are major problems in the HFC CATV networks and the solutions for these problems. Also discussed are data transmission, medium access control, IEEE802.14, and MCNS for standardizations. Moreover, additional telecommunications service activities in both Korea and other countries, using HFC CATV networks are also included. The topics which are covered in detail are the ones such as interoperation between HFC CATV networks and trunk line and the digital transmission performance test for the CATV networks. In the performance test, it is concluded that HFC CATV networks can satisfy the QoS for various additional services if the number of the subscribers in a cell is limited to less than 500 and other minor requirements are satisfied. Based on all these discussions and conclusions, HFC CATV networks are suggested in this paper for the subscriber access networks of the so called information superhighway.

• Journal of the Institute of Electronics Engineers of Korea TC
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• 제46권5호
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• pp.122-129
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• 2009

In this paper, we have proposed the QoS (quality of services) control scheme which can adjust data transfer rates of the session participants in response to their radio channel conditions under the time-varying propagation radio environment. The outage probability is selected as the performance index in order to compare the performance of the proposed scheme with the conventional QoS control scheme. The outage probability of the single and multiple paths is mathematically derived here and its numerical results are investigated. The results show that the significant performance improvement can be obtained compared with the conventional scheme and also the diversity gain can improve the radio link outage as the degrees of the multipath diversity increases. Therefore the overall performance improvement in terms of the QoS of the outage probability can be significantly be achieved by applying the proposed scheme.