• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.271-274
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• 1996

In this paper we made a reliability analysis of power system pumps by using the dimensional reduction method which over comes the problem due to unavailability of enpugh data in the actual systems under many different operational environments. Hence a resonable method was proposed to determine the optimum maintenance interval of given pump in thermal power stations. This analysis was based on an actual data set of pumps for over ten years in thermal power stations belonged to Kyushu Electric Power Company, Japan.

• 제어로봇시스템학회논문지
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• 제13권6호
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• pp.531-536
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• 2007

This paper presents a power quality assessment model based on the Analytic hierarchy process. This model can assess unified power quality index which provide an overall performance of the distribution system. To obtain the unified power quality index, we propose the use of the AHP model which has three states: [Ideal]-[Actual]-[Worst]. The proposed method is especially useful and effective for planning. We have applied the proposed method to an actual relatively large system, and verified the usefulness.

• 전기학회논문지
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• 제67권11호
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• pp.1455-1462
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• 2018

As the interests in eco-friendly energy has increased, the interests in Electric Vehicles(EVs) are increasing as well. Moreover, due to the government's economic support for EVs, penetration level of it has rapidly increased. These sharp increases, however, induce various problems in distribution system, such as voltage/frequency variations, peak demand increasement, demand control, etc. To minimize these possible matters, lots of research have conducted. Nevertheless, most of it assumed extremely important factors, such as numbers and charging patterns of EVs. It inevitably results in errors in their research, and thus make it difficult to prevent the possible matters from EVs. In this paper, therefore, we use actual EVs charging data from KEPCO, and analysis and deduction of it were conducted. The simulations were carried out for four aspect(season, region, purpose).

• 드라이브 ㆍ 컨트롤
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• 제19권1호
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• pp.43-50
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• 2022

The aim of this study was to conduct basic research on the development of a dual-clutch transmission(DCT) and automatic transmission for agricultural tractors. The DCT layout and the DCT simulation model were developed using commercial software. Power transmission efficiency of the DCT and component power loss were analyzed to verify the developed simulation model. Power loss analysis of the components was conducted according to previous studies and ISO(International Organization for Standardization) standards. The power transmission efficiency of the DCT simulation model was 68.4-91.5% according to the gear range. The power loss in the gear, bearing, and clutch DCT system components was 0.75-1.49 kW, 0.77-2.99 kW, and 5.24-10.52 kW, respectively. The developed simulation model not include the rear axle, differential gear, final reduction gear. Therefore actual power transmission efficiency of DCT will be decreased. In a future study, an actual DCT can be developed through the simulation model in this study, and optimization design of DCT can be possible by comparing simulation results and actual vehicle test.

• 전기학회논문지
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• 제59권11호
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• pp.2012-2015
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• 2010

In this paper, the mathematical models of the superheater and the desuperheater are derived based on the fundamental laws of physics, mass and energy balance. The parameters of the models are developed for the 500[MW] thermal power plant using the actual data. The simulated model outputs are well matched with the actual ones. It is expected that the proposed models are useful for the temperature controller design of the thermal power plant.

• 유통과학연구
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• 제17권12호
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• pp.63-70
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• 2019

Purpose: This study was to propose effective deployment of automatic external defibrillators (AEDs) installed at general supermarkets. Research design, data, and methodology : We conducted interview and data surveys on 72 large distributors in Seoul and Gyeonggi province in South Korea. The content of this survey was consisted of general status on the general supermarkets, AED deployment and management regarding public access defibrillation (PAD). G^⁎Power (v 3.1.9.4; Universität Kiel, Kiel, Germany) was also used to analyze statistical power. Radius and actual distance, radius and retrieval time were compared by t-test at α=.05. respectively. Results : Difference between the radius (102.7 meters) and the actual distance (187.8 meters) was 85.1m, it had statistically significant difference (p<.001). The actual distance was longer compared to the radius distance. Difference between the radius (114.1 seconds) and the retrieval time (208.7 seconds) was 94.6s, it had statistically significant difference (p<.001). The retrieval time took longer compared to the radius time as well. Conclusions : The finding shows that only 45.9% of the general supermarkets are satisfied with the actual AED coverage within 3 minutes. This needs to enhance AED deployment to reduce defibrillation time and AED management to boost application in South Korea.

• Journal of Electrical Engineering and Technology
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• 제10권6호
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• pp.2240-2248
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• 2015

The integration of the large-scale wind power brings great challenge to the stability of the power grid. This paper investigates and studies the fault on May 14, 2012 of the large-scale cascading trip-off of wind turbines in North China. According to the characteristics of the voltage variation, the fault process is divided into three stages: the pre-event stage, the critical stage before cascading, and the cascading stage. The scenes in the fault are reproduced, using the full-size actual power system model. Simulation models of double-fed induction generators (DFIGs) and SVCs including protection settings and controller strategies are carefully chosen to find out the reason of voltage instability in each stage. Some voltage dynamic that have never been observed before in the faults of the same kind are analyzed in detail, and an equivalent voltage sensitive dynamic model of DFIG is proposed for the fast computation. The conclusions about the voltage dynamics are validated by the actual PMU observation evidence.

• Journal of Power Electronics
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• 제3권4호
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• pp.239-248
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• 2003

This paper presents a novel prototype of three-phase voltage source type zero voltage soft-switching inverter with the auxiliary resonant snubbers suitable for high-power applications with IGBT power module packages in order to reduce their switching power losses as well as electromagnetic conductive and radiative noises. A proposed single inductor-assisted resonant AC link snubber circuit topology as one of some auxiliary resonant commutation snubbers developed previously to achieve the zero voltage soft-switching (ZVS) for the three-phase voltage source type sinewave PWM inverter operating under the instantaneous space voltage vector modulation is originally demonstrated as compared with the other types of resonant AC link snubber circuit topologies. In addition to this, its operation principle and unique features are described in this paper. Furthermore, the practical basic operating performances of the new conceptual instantaneous space voltage vector modulation resonant AC link snubber-assisted three-phase voltage source type soft-switching PWM inverter using IGBT power module packages are evaluated and discussed on the basis of switching voltage and current waveforms, output line to line voltage quality, power loss analysis, actual power conversion efficiency and electromagnetic conductive and radiative noises from an experimental point of view, comparing with those of conventional three-phase voltage source hard-switching PWM inverter using IGBT power modules.

• 전기학회논문지
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• 제67권2호
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• pp.224-232
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• 2018

According to government policy, renewable energy facility such as solar power generation is being implemented for newly constructed buildings. In recent years, the introduction of Energy Storage System (ESS) served as an emergency power for replacing an existing diesel generator has been increasing. Furthermore, in order to expand the efficacy of the ESS operation, operation in combination with renewable energy sources such as solar and wind power generation is increasing. Hence, development of the ESS operation algorithms for emergency mode as well as the peak power cut mode, which is the essential feature of ESS, are necessary. The operational scenarios of ESS need to consider load power requirement and the amount of the power generation by renewable energy sources. For the verification of the developed scenarios, tests under the actual situation are demanded, but there is a difficulty in simulating the emergency operation situation such as system failure in the actual site. Therefore, this paper proposes simulation models for the HILS(Hardware In the Loop Simulation) and operation modes developed through HILS for the ESS operated with renewable energy source under peak power reduction and emergency modes. The paper shows that the ESS operation scenarios developed through HILS work properly at the actual site, and it verifies the effectiveness of the control logic developed by the HILS.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.1-10
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• 2017

With the current global need for eco-friendly energies, the large scale use of Electric Vehicles (EVs) is predicted. However, the need to frequently charge EVs to an electrical power system involves risks such as rapid increase of demand power. Therefore, in this paper, we propose a practical smart EV charging scheme considering a Time-of-Use (ToU) price to prevent the rapid increase of demand power and provide load leveling function. For a more practical analysis, we conduct simulations based on the actual distribution system and driving patterns in the Republic of Korea. Results show that the proposed method provides a proper load leveling function while preventing a rapid increase of demand power of the system.