• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.477-483
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• 2000

Fly ash is the unburned residue resulting from the combustion of coal in utility and industrial boilers such as thermal power plants. Annually about 5 million tons of fly ash is being produced in korea. Less than 25 percent of total volume of fly ash is currently being used effectively for some ways. In the future, the volume of fly ash discharge from thermal power stations will be increasing more and more, and the development of the utilization of high volume fly ash is required. Fly ash has a lower compacted density and specific gravity than coarse grained natural aggregates but equivalent strength properties indicating that the fly ash could be used as a structural fill materials. So, clay-fly ash mixtures can be used as a fill material in the construction of embankments. Laboratory tests have been carried out to determine the physical, chemical, and geotechnical characteristics of the clay and fly ash. The fly ash is mixed with the clay in different proportions and the geotechnical characteristics of the mixtures have been studied also. In this study describes the results of the experimental study. The implications of the use of clay and clay-fly ash mixtures on the stability of embankments are discussed.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.29 no.2
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• pp.1-11
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• 2016

Objective : The purpose of this study is to analyze research trends on the cost-effectiveness in acupuncture for patients with allergic rhinitis. Methods : The literature and research in allergic rhinitis was searched in electronic databases, such as National Health Service Economic Evaluation Database(NHS EED) and the Cochrane Database of Systematic Reviews(CDSR). The general characteristics and the results of each economic analysis such as incremental cost-effectiveness ratios(ICERs) were extracted. Results : In total, thirty seven studies were searched, and two studies were analyzed. They were cost-utility analysis(CUA)s that measured quality-adjusted life years(QALYs). One study showed that the ICER was €22,798 per QALY and was robust in sensitivity analysis. Another showed that the ICER was between €31,241 and €118,889 from society's perspective and between €20,807 and €74,585 from a third-party payer's perspective. Conclusions : Any generalization of these results needs to be made with caution given the specific effects of acupuncture and the difference of cost data in the various countries. Further studies are needed on this topic in order to demonstrate the cost-effectiveness clearly.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.11a
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• pp.377-382
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• 2005

This paper presents two new circuit topologies of DC bus lineside active edge resonant snubber assisted soft-switching PWM full-bridge DC-DC converter acceptable for either utility AC 200V-rms or AC 400V-rms input voltage source. One topology of proposed DC-DC converters is composed of a typical voltage source-fed full-bridge high frequency PWM inverter using DC busline side series power semiconductor switching devices with the aid of a parallel capacitive lossless snubber. All the active power switches in the full-bridge arms and DC busline can achieve ZCS turn-on and ZVS turn-off commutations and the total turn-off switching power losses of all active switches can be reduced for high-frequency switching action. It is proved that the more the switching frequency of full-bridge soft switching inverter increases, the more soft-switching PWM DC-DC converter with a hish frequency transformer link has remarkable advantages for its efficiency and power density as compared with the conventional hard-switching PWM inverter type DC-DC converter

• Journal of Communications and Networks
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• v.9 no.3
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• pp.319-329
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• 2007

This paper presents a price-based quality-of-service (QoS) control framework for two-class network services, in which circuit-switched and packet-switched services are defined as "premium service class" and "best-effort service class," respectively. Given the service model, a customer may decide to use the other class as a perfect or an imperfect substitute when he or she perceives the higher utility of the class. Given the framework, fixed-point problems are solved numerically to investigate how static pricing can be used to control the demand and the QoS of each class. The rationale behind this is as follows: For a network service provider to determine the optimal prices that maximize its total revenue, the interactions between the QoS-dependent demand and the demand-dependent QoS should be thoroughly analyzed. To test the robustness of the proposed model, simulations were performed with gradually increasing customer demands or network workloads. The simulation results show that even with substantial demands or workloads, self-adjustment mechanism of the model works and it is feasible to obtain fixed points in equilibrium. This paper also presents a numerical example of guaranteeing the QoS statistically in the short term-that is, through the implementation of pricing strategies.

• Journal of Power Electronics
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• v.4 no.2
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• pp.102-111
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• 2004

This paper is concerned with a deadbeat current control implementation of shunt-type three-phase active power filter (APF). Although the one-dimensional deadbeat control method can attain time-optimal response of APF compensating current, one sampling period is actually required fur its settling time. This delay is a serious drawback for this control technique. To cancel such a delay and one more delay caused by DSP execution time, the desired APF compensating current has to be predicted two sampling periods ahead. Therefore an adaptive predictor is adopted for the purpose of both predicting the control error of two sampling periods ahead and bringing the robustness to the deadbeat current control system. By adding the adaptive predictor output as an adjustment term to the reference value of half a source voltage period before, settling time is made short in a transient state. On the other hand, in a steady state, THD (total harmonic distortion) of the utility grid side AC source current can be reduced as much as possible, compared to the case that ideal identification of controlled system could be made.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.916-918
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• 1996

We have an urgent matter that is lack of energy resource. So we have to accomplish the design of economical energy utility systems and to develop energy facilities with high efficiency. Cogeneration system is one of them. It has high efficiency and can solve unbalanced electricity and heat demand in Summer & Winter concurrently. Recently, to increase the efficiency and stability of the total system, it is applying automatic control and monitoring software to the hardware facilities in industrial control systems. Therefore, these systems has been researched and developed in the advanced countries. It also has been researched and developed in the domestic since '60. But the control and monitoring software in cogeneration system has been hardly developed and has been imported expensive products from the advanced countries. In this study, we have developed the software of operating control, status monitoring, operating data managing and tele-controlling. We have confirmed usefullness of developed software by applying to gas turbine cogeneration system.

• Smart Media Journal
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• v.8 no.4
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• pp.72-79
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• 2019

The automated demand response (DR) program encourages consumers to participate in grid operation by reducing power consumption or deferring electricity usage at peak time automatically. However, successful deployment of the automated DR program sphere needs careful assessment of appliances load profile (ALP). To this end, the recent method estimates frequency, consistency, and peak time consumption parameters of the daily ALP to compute their potential score to be involved in the DR event. Nonetheless, as the daily ALP is subject to varying with respect to the DR time ALP, the existing method could lead to an inappropriate estimation; in such a case, inappropriate appliances would be selected at the automated DR operation that effected a consumer comfort level. To address this challenge, we propose a more proper method, in which all the three parameters are calculated using ALP that overlaps with DR time, not the total daily profile. Furthermore, evaluation of our method using two public residential electricity consumption data sets, i.e., REDD and REFIT, shows that our energy management systems (EMS) could properly match a DR target. A more optimal selection of appliances for the DR event achieves a power consumption decreasing target with minimum comfort level reduction. We believe that our approach could prevent the loss of both utility and consumers. It helps the successful automated DR deployment by maintaining the consumers' willingness to participate in the program.

• Journal of Power Electronics
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• v.7 no.2
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• pp.146-158
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• 2007

A multi-pulse GTO based voltage source converter (VSC) topology together with a fundamental frequency switching mode of gate control is a mature technology being widely used in static synchronous compensators (STATCOMs). The present practice in utility/industry is to employ a high number of pulses in the STATCOM, preferably a 48-pulse along with matching components of magnetics for dynamic reactive power compensation, voltage regulation, etc. in electrical networks. With an increase in the pulse order, need of power electronic devices and inter-facing magnetic apparatus increases multi-fold to achieve a desired operating performance. In this paper, a competitive topology with a fewer number of devices and reduced magnetics is evolved to develop an 18-pulse, 2-level $\pm$ 100MVAR STATCOM in which a GTO-VSC device is operated at fundamental frequency switching gate control. The inter-facing magnetics topology is conceptualized in two stages and with this harmonics distortion in the network is minimized to permissible IEEE-519 standard limits. This compensator is modeled, designed and simulated by a SimPowerSystems tool box in MATLAB platform and is tested for voltage regulation and power factor correction in power systems. The operating characteristics corresponding to steady state and dynamic operating conditions show an acceptable performance.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.6
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• pp.711-719
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• 2019

At present, wind power is the fastest growing technology in the world. The domestic market depends heavily on imports for wind tower lift. so it manage through the overseas maker. The lift manufacture, establishment and maintenance utility is increasing, localization development of one wind tower lift is necessary with domestic fundamental base technique. In this paper, we will study the components necessary for the development of onshore offshore wind tower elevators, which are currently dependent on total imports, in line with the high growth of the wind market and the enlargement of the wind power generators. First of all, endless winders and cabins, which are the core components of the offshore wind tower lift, were examined for the components that affect the structural safety. Structural analysis was performed on Sheave, which is responsible for most of the lift lifting loads, and Block Stop, a safety device that prevents the cabin from falling in an emergency. The structural suitability was evaluated by comparing with the safety factor. In addition, the on-board control panel combines the control panel of the elevator and the drive motor driving the endless winder for efficient control of the offshore wind tower lift. The addition of features improves ride comfort at departure.

• Korean Journal of Clinical Laboratory Science
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• v.46 no.2
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• pp.47-53
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• 2014

The purpose of this study was to evaluate the clinical utility of TB/NTM PCR by comparing the results of TB PCR to detect Mycobacterium tuberculous (MTB) and nontuberculous mycobacteria (NTM) from paraffin-embedded tissue specimens. A total of 60 cases were tested using TB PCR and TB/NTM PCR. The MTB and NTM rate of TB/NTM PCR was 84.2% (16/19), 10.5% (2/19) in TB positive of TB PCR. The NTM rate of TB/NTM PCR was 29.3% (12/41) in TB negative of TB PCR. Fourteen different species of NTM were identified, the common isolate was M. gordonae (21.4%), M. avium (14.3%), M. ulcerans (7.1%), M. interjectum (7.1%), M. gilvum (7.1%), M. fortuitum (7.1%), M. mucogenicum (7.1%). The rare species identified were M. farcinogenes (7.1%), M. tokaiense (7.1%). Therefore, TB/NTM PCR is useful to differentiate MTB and NTM from paraffin-embedded tissue specimens and it is more effective in detecting NTM with TB PCR.