• Journal of the Korean Institute of Intelligent Systems
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• v.13 no.3
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• pp.366-370
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• 2003

In this research, we suggest a hybrid intelligent Web recommendation systems based on Web data mining and case-based reasoning (CBR). One of the important research topics in the field of Internet business is blending artificial intelligence (AI) techniques with knowledge discovering in database (KDD) or data mining (DM). Data mining is used as an efficient mechanism in reasoning for association knowledge between goods and customers＇ preference. In the field of data mining, the features, called attributes, are often selected primary for mining the association knowledge between related products. Therefore, most of researches, in the arena of Web data mining, used association rules extraction mechanism. However, association rules extraction mechanism has a potential limitation in flexibility of reasoning. If there are some goods, which were not retrieved by association rules-based reasoning, we can＇t present more information to customer. To overcome this limitation case, we combined CBR with Web data mining. CBR is one of the AI techniques and used in problems for which it is difficult to solve with logical (association) rules. A Web-log data gathered in real-world Web shopping mall was given to illustrate the quality of the proposed hybrid recommendation mechanism. This Web shopping mall deals with remote-controlled plastic models such as remote-controlled car, yacht, airplane, and helicopter. The experimental results showed that our hybrid recommendation mechanism could reflect both association knowledge and implicit human knowledge extracted from cases in Web databases.

• Journal of Magnetics
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• v.18 no.3
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• pp.302-307
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• 2013

Hybrid-type magnetic bearings using both permanent magnets and electromagnets have been used for rotating machinery. In the case of conventional thrust hybrid magnetic bearings supporting axial loads, radially magnetized permanent ring magnets, which have several demerits such as difficult magnetization and assembly, have been used to generate bias flux. In this study, a novel thrust hybrid magnetic bearing using an axially magnetized permanent ring magnet is presented. Because it is easy to magnetize a ring magnet in the axial direction, the segmentation of the ring magnet for magnetization is not required and the assembly process can be simplified. For verifying the performance of the proposed method, a test rig that consists of a proposed thrust magnetic bearing and variable loads is constructed. This paper presents the detailed design procedures and the obtained experimental results. The results show that the developed thrust magnetic bearing has the potential to replace conventional thrust magnetic bearings.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.1
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• pp.280-294
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• 2023

Unmanned aerial vehicles (UAVs) and millimeter-wave frequencies play key roles in supporting 5G wireless communication systems. They expand the field of wireless communication by increasing the data capacities of communication systems and supporting high data rates. However, short wavelengths, owing to the high millimeter-wave frequencies can cause problems, such as signal attenuation and path loss. To address these limitations, research on high directional beamforming technologies continue to garner interest. Furthermore, owing to the mobility of the UAVs, it is essential to track the beam angle accurately to obtain full beamforming gain. This study presents a beam tracking method based on the unscented Kalman filter using hybrid beamforming. The simulation results reveal that the proposed beam tracking scheme improves the overall performance in terms of the mean-squared error and spectral efficiency. In addition, by expanding analog beamforming to hybrid beamforming, the proposed algorithm can be used even in multi-user and multi-stream environments to increase data capacity, thereby increasing utilization in new-radio multiple-input multiple-output orthogonal frequency-division multiplexing systems.

• The Journal of the Acoustical Society of Korea
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• v.27 no.3E
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• pp.95-103
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• 2008

In this paper, the new hybrid adaptive Volterra filter was proposed to be applied for compensating the nonlinear distortion of memoryless nonlinear systems with saturation characteristics. Through computer simulations as well as the analytical analysis, it could be shown that it is possible for both conventional Volterra filter and proposed hybrid Volterra filter, to be applied for linearizing the memoryless nonlinear system with nonlinear distortion. Also, the simulations results demonstrated that the proposed hybrid filter may have faster convergence speed and better capability of compensating the nonlinear distortion than the conventional Volterra filter.

• Journal of the Korean Society for Railway
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• v.13 no.2
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• pp.152-158
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• 2010

Generally, the AC electrified railway systems have the power quality problems that are induced from the harmonic currents and the reactive power. This paper presents a single-phase hybrid active filter adopting a SRF(synchronous-reference-frame) control for improving power quality in the AC electrified railway systems. The single-phase hybrid active filter can compensate the harmonic currents and the reactive power through the proposed SRF control algorithm. The proposed control algorithm can extract the third and fifth harmonics through the MSRF(multiple-synchronous-reference-frames) which is used to apply the three-phase systems. Therefore, the hybrid active filter can compensates only the high-frequency harmonic currents whereas the passive filter compensates the low-frequency harmonic currents. Also, the proposed SRF control algorithm can compensate the reactive power by the closed-loop control. The Validity and the effectiveness of the proposed SRF control method for the hybrid active filter are illustrated through the simulation results.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.2
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• pp.143-149
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• 2008

A novel compact model for a five-port transformer balun is proposed for the efficient circuit design of hybrid balun. Compared to the conventional model, the proposed model provides much faster computation time and more reasonable values for the extracted parameters. The hybrid balun, realized in $0.18\;{\mu}m$ CMOS, achieves 2.8 dB higher gain and 1.9 dB lower noise figure than its passive counterpart only at a current consumption of 0.67 mA from 1.2 V supply. By employing the hybrid balun, a differential zero-IF receiver is designed in $0.18\;{\mu}m$ CMOS for IEEE 802.15.4 ZigBee applications. It is composed of a differential cascode LNA, passive mixers, and active RC filters. Comparative investigations on the three receiver designs, each employing the hybrid balun, a simple transformer balun, and an ideal balun, clearly demonstrate the advantages of the hybrid balun in fully differential CMOS RF receivers. The simulated results of the receiver with the hybrid balun show 33 dB of conversion gain, 4.2 dB of noise figure with 20 kHz of 1/f noise corner frequency, and -17.5 dBm of IIP3 at a current consumption of 5 mA from 1.8 V supply.

• Restorative Dentistry and Endodontics
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• v.28 no.6
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• pp.491-497
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• 2003

The purpose of this study was to evaluate the correlation between hybrid layer thickness and bond strength using confocal laser scanning microscope and microtensile bond strength test of two adhesive systems. The dentin surface of human molars. sectioned to remove the enamel from the occlusal surface. Either Scotchbond Multi-Purpose(3M Dental Product, St. Paul, MN, U.S.A) or Clearfil SE Bond (Kuraray, Osaka, Japan) was bonded to the surface. and covered with resin-composite. The resin-bonded teeth were serially sliced perpendicular to the adhesive interface to measure the hybrid layer thickness by confocal laser scanning microscope. The specimen were trimmed to give a bonded cross-sectional surface area of $1\textrm{mm}^2$, then the micro-tensile bone test was performed at a cross head speed of 1.0 mm/min. All fractured surfaces were also observed by stereomicroscope. There was no significant differences in bond strengths the materials(p>0.05). However. the hybrid layers of three-step dentin adhesive system, SM, had significantly thicker than self-etching adhesive system. CS(p<0.05). Pearson's correlation coefficient showed no correlation between hybrid layer thickness and bond strengths(p>0.05). Bond strengths of dentin adhesive systems were not dependent on the thickness of hybrid layer.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.377-382
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• 1986

This paper describes the modelling method of hybrid step motors including magnetic saturation effects of iron parts and the simulation for design of a prototype. Based on the above procedure, the prototype of a step motor is produced and its characteristics are discussed.

• Environmental and Resource Economics Review
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• v.15 no.4
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• pp.693-712
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• 2006

A pre-feasibility test is done for renewable energy hybrid power systems at off~grid islands in which the current power supply is provided only by diesel generation. We apply Homer (Hybrid Optimization Model for Electric Renewables) which was developed by the National Renewable Energy Laboratory (NREL) for the analysis to identify the cost-minimizing combination of power generating facilities for the given load profiles. Chuja-Do, Geomun-Do and Youngsan-Do have been selected for our analysis considering the wind resources data of the Korea Institute of Energy Research (KIER). Information on wind speed, solar radiation and temperature is also used for the analysis. System component cost information from overseas market has been used due to the lack of domestic information. Site specific Load profile for electricity demand for those islands are reconstructed based on the partial survey results obtained form other sources. The LCOE of the least cost hybrid power systems for Chuja-Do, Geomun-Do and Youngsan-Do are $0.278/kWh, $0.234/kWh and $0.353/kWh, respectively Considering the fact that diesel generation is being subsidized at the price of $0.300/kWh by the government, first 2 cases are economically feasible for the introduction of renewable energy hybrid systems to those islands. But the third case of Youngsan-Do does not meet the criteria. The basic differences of these pre-feasibility test results are from the differences of the site specific renewable energy conditions, especially wind resources. In summary, promoting hybrid systems in the off-grid remote island should be based on the economic feasibility test results. Not all the off-grid islands are feasible for introducing this renewable energy hybrid system.

• Steel and Composite Structures
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• v.18 no.2
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• pp.395-408
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• 2015

The paper considers the free vibration analysis of FGM grid systems. Up to now, very little work has been done on this type of system and the paper aspires to fill this gap. Based on the hybrid-stress finite element formulation free vibration solutions for FGM grid systems of various aspect ratios, different types of gradations functions, and support conditions are determined. The tabulation of these results, not available thus far, should be useful to designers and researchers who may use them.