• Membrane Journal
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• v.16 no.1
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• pp.59-67
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• 2006

Biodegradable amphiphilic polymer was synthesized for removing hydrophobic pollutants(phenol, 4-nitrophenol, benzene, and toluene) and metal ions ($Cs^{+},\;Mg^{2+},\;Cu^{2+},\;Ni^{2+}$, and $Cr^{3}$). The methoxy poly(ethylene glycol)s with different molecular weights (1,100 and 5,000) were used as a hydrophilic segment. The rejection ratio improved in the relatively high molecular weight of MPEG. The rejection ratio of biodegradable nanoparticles without pollutants was over 98%. In removal of hydrophobic pollutants, the rejection ratio increased with the hydrophobic properties. The electron valence affects the rejection ratio of metal ions, indicating rejection ratio was ordered as $3^{+}>2^{+}>1^{+}$.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.393-394
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• 2020

In this paper, an improved rotor speed estimation in DFIG wind turbine systems based on a cascaded SOGI is proposed. Due to excellent harmonics and DC offset rejection capability of the cascaded SOGI, the accurate rotor speed estimation can be achieved despite the harmonics and sensing offset in DFIG currents. The simulation results have verified the validity of proposed method.

• Korean Chemical Engineering Research
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• v.49 no.5
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• pp.565-570
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• 2011

In this paper, the analytical tuning rules of the proportional-integral-derivative (PID) controller have been derived for a broad class of stable, integrating, and unstable processes without time delay. On the basis of the renowned internal model control (IMC) design principles and the two-degree-of-freedom (2DOF) control structure, the proposed method can be effectively used for obtaining the enhanced performances of both the disturbance rejection as well as the set-point tracking problems, since the design scheme is simple, straightforward, and can be easily implemented in the process industry. Several processes without time delay are employed to demonstrate the improved closed-loop performance of the proposed controller design in compared with the other well-known design methods in terms of the same degree of robustness.

• The Journal of the Acoustical Society of Korea
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• v.15 no.4E
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• pp.14-20
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• 1996

The double mode SAW resonator filters have the serious shortcoming that out-of-band rejection above the passband is quite poor. Hence a new structure of the double mode filter is designed with the COM (Coupling Of MOdes) theory with better out-of-band rejection characteristics while keeping all the beauties of the conventional type. The second goal of the design is to reduce the planar size of the structure so that mass productivity of low frequency devices can be improved. For those purposes, several IDT's and relfector gratings are added to or subtracted from the conventional structure so that the modification can lead to better overall performance as a filter. As results of the investigation, several new double mode SAW resonator filter structures are developed. A new structure shows 10dB more out-of-band rejection that the conventional type with 25% reduced device size. Good agreement is demonstrated between the analytical results and experimental results for an illustrative 325MHz four pole resonator filter on 64°YX LiNbO3.

• Membrane and Water Treatment
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• v.8 no.6
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• pp.613-623
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• 2017

We report the novel thin film composite RO membrane modified by graphene oxide. The thin film composite RO membrane was exposed to 2000 mg/l sodium hypochloride; thereafter it was subjected to different graphene oxide concentration ranging from 50 mg/l to 1000 mg/l in water. The resultant membrane was crosslinked with 5000 mg/l N-hydroxysuccinimide. The performance of different membranes were analysed by solute rejection and water-flux measurement. It was found that 100 mg/l graphene oxide exposure followed by 5000 mg/l N-hydroxysuccinimide treatment resulted in the membrane with the highest solute rejection of 97.78% and water-flux of 4.64 Liter per sqm per hour per bar g. The membranes were characterized by contact angle for hydrophilicity, scanning electron micrographs for surface morphology, energy dispersive X-Ray for chemical composition of the surface, Atomic force microscope for surface roughness, ATR-FTIR for chemical structure identification. It was found that the graphene oxide modified membrane increases the salt rejection performance after exposure to high-fouling water containing albumin. Highly hydrophilic, antifouling surface formation with the nanomaterial led to the improved membrane performance. Moreover, the protocol of incorporating nanomaterial by this post-treatment is simple and can be applied to any RO membrane after it is manufactured.

• Journal of Korea Multimedia Society
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• v.13 no.10
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• pp.1436-1443
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• 2010

In vocabulary recognition system has it's bad points of processing vocabulary unseen triphone and then no got distribution of confidence measure by cannot normalization. According to this problem to improve suggested VCOR(Version Control for Out-of Rejection) system by out-of vocabulary rejection algorithm use vocabulary management optimization and then phone data search support. In VCOR system to provide vocabulary information efficiently offering for user's vocabulary information using extend facet classification that improved for vocabulary measure management function offering accuracy of recognition for vocabulary. In this paper proposed system performance as a result of represent vocabulary dependence recognition rate of 97.56%, vocabulary independence recognition rate of 96.23%.

• Journal of the Korea Society of Computer and Information
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• v.15 no.12
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• pp.125-132
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• 2010

In vocabulary recognition has unseen tri-phone appeared when recognition training. This system has not been created beginning estimation figure of model parameter. It's bad points could not be created that model for phoneme data. Therefore it's could not be secured accuracy of Gaussian model. To improve suggested Gaussian model to optimized method of model parameter using probability distribution. To improved of confidence that Gaussian model to optimized of probability distribution to offer by accuracy and to support searching of phoneme data. This paper suggested system performance comparison as a result of recognition improve represent 1.7% by out-of vocabulary rejection algorithm using normalization confidence.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.5
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• pp.859-866
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• 2022

Active disturbance rejection control is a method in which the disturbance is removed from the controller by estimating the state variable using the Luenberger observer. The Luenberger observer is estimated by defining a nonlinear term including disturbance with constant characteristics in a steady state as a state variable. It can be shown that the speed tracking performance is improved by compensating the estimated state variable to the PI controller and the IP controller. The disturbance removal performance of the tracking control can be confirmed by observing that the estimated state error is within 1.9 [%] in the case of load fluctuation and the steady-state state tracking error converges to zero.

• Membrane and Water Treatment
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• v.15 no.3
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• pp.139-152
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• 2024

Mixed matrix membranes have gained significant recognition in the wastewater treatment industry for their effectiveness in removing dyes, proteins, and heavy metals from water sources. Researchers have developed an innovative technique to enhance properties of these membranes by incorporating amine-functionalized carbon nanotubes into the polymer matrix. This approach introduces amine functional groups onto the membrane surface, which are then modified with trimesoyl chloride and cyanuric chloride. The modified membranes are characterized by XPS to confirm successful bonding of amines with the trimesoyl chloride and cyanuric chloride. The surface charge of the modified membrane also plays a role in the modification process; the membrane modified with trimesoyl chloride has a negative surface charge, while the one modified with cyanuric chloride has a more positive charge. At the same acidic pH, the positive or negative charge of the mixed matrix membranes assists in enhancing the rejection of heavy metals. This results in improved antifouling properties for both modified membranes. The heavy metal rejection for all modified membranes is higher than for unmodified membranes, due to both adsorption and complexation abilities of the functional groups on the membrane surface with heavy metal ions. As the membrane surface functionalities increase through modification, the separation due to complexation also increases. The bulk morphology of the membrane remains unchanged, while roughness slightly increases due to the surface treatment.

• Journal of IKEEE
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• v.18 no.1
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• pp.1-7
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• 2014

In this paper, we suggest an improved Viola-Jones detection framework for the efficient feature selection and the fast rejection method of the sub-window. Our object detector has low computational complexity because it rejects sub-windows until specific threshold. Owing to using same framework, detection performance is same with the existing Viola-Jones detector. We measure the number of average feature calculation about MIT-CMU test set. As a result of the experiment, the number of average feature calculation is reduced to 45.5% and the detection speed is improved about 58.5% compared with the previous algorithm.