• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.11a
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• pp.452-455
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• 2000

There are increasingly important financial incentives and environmental consideration to improve the effluent quality of wastewater from domestic and industrial users. The activated sludge process is a widely used biological wastewater treatment process. The activated sludge process is complicated due to the many factors such as the variation of influent flowrate and concentration, the complexity of biological reactions and the various operation conditions. Nowadays, not only suspended solids and residual carbon, but also nitrogen and phosphorous concentration of the effluent water must be taken into account for the design and operation of wastewater treatment plants. Also, the effluent quality to be met are more stringent. Therefore, an intelligent control approach is required in order to successful biological nitrogen removal. In this paper, the strategies for dosage of extra carbon in the anoxic zone and DO concentration in the aerobic zone are presented and evaluated through the simulation using the denitrification layout of the IWA simulation benchmark implemented by Matlab$\^$/5.3/Simulink$\^$/3.0. The control strategy to achieve sufficient denitrification rates in an anoxic zone. Methanol is used as an external extra carbon source. The external extra carbon source is required for the nitrogen removal process because nitrogen and organic concentration are fluctuated in the influent flowrate. The dissolved oxygen is calculated by So concentration in the activated sludge model NO.1. The air flowrate of each aerobic reactor is intelligently controlled to achieve the predefined setpoints. Air flowrate is adjusted by the fuzzy logic controller that includes two inputs and one output. The objective function for the optimization procedure is designed to improve effluent quality and reduce the operating cost.

• Wind and Structures
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• v.20 no.3
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• pp.449-468
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• 2015

Current wind-resistance designs of large-scale indirect dry cooling towers (IDCTs) exclude an important factor: the influence of the ventilation rate for radiator shutter on wind loads on the outer surfaces of the tower shell. More seemingly overlooked aspects are the effects of various ventilation rates on the wind pressure distribution on the tower surfaces of two IDCTs, and the feature of the flow field around them. In order to investigate the effects of the radiator shutter ventilation rates on the aerodynamic interference between IDCTs, this paper established the numerical wind tunnel model based on the Computational Fluid Dynamic (CFD) technology, and analyzed the influences of various radiator shutter ventilation rates on the aerodynamic loads acting upon a single and two extra-large IDCTs during building, installation, and operation stages. Through the comparison with the results of physical wind tunnel test and different design codes, the results indicated that: the influence of the ventilation rate on the flow field and shape coefficients on the outer surface of a single IDCT is weak, and the curve of mean shape coefficients is close to the reference curve provided by the current design code. In a two-tower combination, the ventilation rate significantly affects the downwind surface of the front tower and the upwind surface of the back tower, and the larger positive pressure shifts down along the upwind surface of the back tower as the ventilation rate increases. The ventilation rate significantly influences the drag force coefficient of the back tower in a two-tower combination, the drag force coefficient increases with the ventilation rate and reaches the maximum in a building status of full ventilation, and the maximum drag coefficient is 11% greater than that with complete closure.

• The Journal of the Korea Contents Association
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• v.15 no.6
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• pp.487-498
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• 2015

The main purpose of this study was to examine the relationship among hoteliers' emotional labor like surface acting (SA) and deep acting (DA), job stress such as physical stress (PS) and mental stress (MS), and extra-role behavior (EB). Using data from 264 surveys collected from five-star hotels' employees, the author empirically tested the research model. Main results on applying structural equation analysis are as follows. (1) SA had positive impacts on both PS and JS while DA was negatively significant on only MS. (2) ER was influenced by DA while there was no significance on SA. (3) MS was negatively related to ER, and PS was also significantly effective; however, the estimate of PS indicated a positive correlation unlike theoretical prediction. In conclusion, a discussion about the interesting phenomenon was held based on self-rewarding acts.

• Korean Journal of Acupuncture
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• v.26 no.2
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• pp.75-89
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• 2009

Objectives: Warm needling combines simultaneously the effects of acupuncture and moxibustion. This study was to investigate whether warm needling could relieve acute knee arthritis induced by carrageenan in rats. Methods: To illuminate the underlying mechanisms of the warm needling-induced antinociception, weight bearing force (WBF) was observed on the acute knee arthritic rat model. Under general anesthesia, ST36, SP9, Hakjung extra point, LI4 were punctured and stimulated with 30 mg moxa ball combustion on top of the needle (${\emptyset}0.18{\times}8mm$). Results: In behavioral test, rats subsequently showed a reduced stepping force of the affected limb 3 hours after the induction of arthritis. Warm needling on the contralateral or ipsilateral ST36 failed to show antinociceptive effect on the acute knee arthritis. Warm needling on the contralateral SP9 or LI4 increased WBF values to normal level in the acute stage of the arthritis. Warm needling on the Hakjung extra-point resulted in the significant antinociceptive effects through acute stage. These effects of warm needling were suppressed by opioids receptor antagonist naltrexone (10 mg/kg, i.p.) and alpha adrenoceptor antagonist phentolamine (5 mg/kg, i.p.). Conclusion: The data suggest that warm needling-induced antinociception is differently mediated by acupoints and accomplished by activating the descending inhibitory systems including endogenous opioids and $\alpha$-adrenoceptors.

• Asia Marketing Journal
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• v.7 no.3
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• pp.1-27
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• 2005

This study investigated the effects of two types of customer extra-role behavior (citizenship and badness behavior) on perceived service quality, customer satisfaction, and repurchase intention. The model was tested with a sample of sports center customers by using structural equation modeling. The findings supported the effects of customer citizenship and badness behavior, and all structural path coefficients were significant. However, the differential effects of customer citizenship and badness behavior on perceived service quality were not significant. Lastly, perceived service quality fully mediated the effects of customer citizenship and badness behavior on customer satisfaction and repurchase intention. The results of the present study demonstrate that service organizations need to manage all two types of customer behavior. Further, it provides new insights into the relationships among customer's extra-role behavior, customer satisfaction, and repurchase intention.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.3019-3021
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• 2005

In this paper we suggest a novel temperature detection method utilized in direct over-temperature protection circuit modeling. The suggested model detects temperature variation using Rds(on) characteristics of MOSFET, while the conventional methods are using extra devices such as a temperature sensor or an over-temperature detection transistor. The temperature-dependant MOSFET model is implemented using Spice ABM(Spice Analog Behavior Model). The direct over-temperature protection circuit was designed including it. We verified effectiveness of the temperature dependant Rds(on) model characteristics and performance of the direct over-temperature protection circuit on PSpice simulation

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.2
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• pp.169-176
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• 2016

In this paper, further research is carried out to investigate the resistance encountered by an icebreaking vessel travelling through level ice and channel ice at low speed range. The present paper focuses on experimental and calculated ice resistances by some empirical formulas in both level ice and channel ice. In order to achieve the research, extra model tests have been done in an ice basin. Based on the measurements from model test, it is found that there exists a relationship between ice resistance, minimum ice load, maximum ice load and the standard deviation of ice load for head on operation in level ice. In addition, both level ice resistance and channel ice resistance are calculated and compared with model test results.

• Journal of the Korean Mathematical Society
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• v.50 no.4
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• pp.695-713
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• 2013

We formulate and study a predator-prey model with non-monotonic functional response type and weak Allee effects on the prey, which extends the system studied by Ruan and Xiao in [Global analysis in a predator-prey system with nonmonotonic functional response, SIAM J. Appl. Math. 61 (2001), no. 4, 1445-1472] but containing an extra term describing weak Allee effects on the prey. We obtain the global dynamics of the model by combining the global qualitative and bifurcation analysis. Our bifurcation analysis of the model indicates that it exhibits numerous kinds of bifurcation phenomena, including the saddle-node bifurcation, the supercritical and the subcritical Hopf bifurcations, and the homoclinic bifurcation, as the values of parameters vary. In the generic case, the model has the bifurcation of cusp type of codimension 2 (i.e., Bogdanov-Takens bifurcation).

• ETRI Journal
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• v.28 no.5
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• pp.692-695
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• 2006

Recently, there has been a constant barrage of worms over the Internet. Besides threatening network security, these worms create an enormous economic burden in terms of loss of productivity not only for the victim hosts, but also for other hosts, as these worms create unnecessary network traffic. Further, measures taken to filter these worms at the router level incur additional network delays because of the extra burden placed on the routers. To develop appropriate tools for thwarting the quick spread of worms, researchers are trying to understand the behavior of worm propagation with the aid of epidemiological models. In this study, we present an optimization model that takes into account infection and treatment costs. Using this model we can determine the level of treatment to be applied for a given rate of infection spread.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.1307-1312
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• 2009

Design is an act based on multidisciplinary information. The involvement of various stakeholders makes it difficult to process, plan, and integrate. Iteration is frequent in most of the engineering design and development projects including construction. Design iterations cause rework, and extra efforts are required to get the optimal sequence and to manage the projects. The simple project management techniques are insufficient to fulfill the requirements of integrated design. This paper entails two things: design structure matrix and design parameters' information based model. The emphasis has been given to optimal sequence and crucial iteration using design structure matrix analysis technique. The design projects have been studied using survey data from industry. The optimal sequence and crucial iterations results have been utilized for proposed model. Model integrates two things: information about produced- required key design parameters and information of design changes during the design process. It will help to get familiar with Design management in order to fulfill contemporary needs.