• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1117-1119
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• 2001

This paper describes the forward type pulse power supply using a Power-MOSFET in the view of commercialization. The principle of basic operating and the operating characteristics of the forward type pulse power supply are estimated by the switching frequency, coupling factor and duty ratio. It is shown that theoretical and experimental results are in good agreement by comparing simulation and experimental results when a lamp type ozonizer can be used as a load. Also, experimental results indicate that the discharge and ozone concentration characteristics of the manufactured pulse power supply is more improved compare to the conventional pulse power supply[5]. This proposed supply show that it can be practically used as a pulse power supply in various environment improvement facilities.

• International Journal of Fluid Machinery and Systems
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• v.9 no.3
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• pp.277-286
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• 2016

The development of heavy-duty process pumps, usually based on various design criteria, depends on the pump's application. The most important criteria are Q-H, efficiency and NPSH characteristics. Cavitation due to inlet recirculation is not often one of the design criteria, although many problems in pump operation appear because of inlet recirculation, when the operation range is from 0.5-0.8 $Q_{opt}$. The present paper shows that steady state CFD analysis of inlet recirculation can give quite good results for the design of new hydraulic shapes, which have been developed to expand operating range and to minimize the harmful influence of recirculation at part load. In this paper, the structures of inlet recirculation are presented, as well as detailed shapes of vortices between the blades for various operating regimes, axial velocity distribution at the impeller inlet, the experimental results of NPSH and efficiency characteristics of an existing and newly designed pump.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.6
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• pp.128-139
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• 2000

Environmental concerns and shortage of petroleum have promoted considerable interest in the use of alternate fuels in stationary diesel engine. In this study, a heavy-duty, intercooler-turbocharged 6-cylinder stationary diesel engine was converted into stationary gas engine fueled with propane or natural gas for the cogeneration plants. One of the most important factors in the combustion features of a stationary gas engine is the fuel composition and operating parameters in terms of compression ratio, spark advance, and engine loads. Experiments with different fuel gas and load conditions were carried out with combustion pressure analysis and NOx measurement. Combustion analysis based on P-$\theta$ diagrams was also investigated by means of combustion duration and cycle variation. Compression ratio is 10.0 and ignition timing is set by using the gasoline setting as a base line and advanced toward BTDC. The results show that fuel composition and spark advance have dominant effects on combustion and NOx characteristics at operating conditions.

• International Journal of Aeronautical and Space Sciences
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• v.1 no.2
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• pp.22-29
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• 2000

A method to simulate the gas turbine transient behavior is developed. The basic principles of the method and main input data required are described. Calculation results are presented in terms of whole operating regime of the engine. The influence of initial parameters such as starting engine power, moment of inertia of the rotor, fuel schedule on performance characteristics of gas turbine during transient operation is shown. In addition, the effect of bleeding air on transient behavior is also considered. For validation of the developed computer code, a comparative analysis with experimental data obtained from a heavy duty gas turbine is made. Calculation results agree well with the experimental data for the range of operating regime studied and proved applicability of the developed technique to initial design stage of control system.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.299-303
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• 2011

This paper proposes a novel sensorless maximum power point tracking (11PPT) algorithm for PV systems. The method is based on dividing the operating time into several intervals in which the PV terminals are short circuited in one interval and the calculated short-current of the PV is obtained and used to determine the optimum operating point where the maximum output power can be obtained. The proposed MPPT algorithm has been introduced into a current-controlled boost converter whose duty ratio is controlled to the maintain MPP condition. The same sequence is then repeated regularly capturing the PV maximum power. The main advantage of this method is eliminating the current sensor. Meanwhile, this MPPT algorithm reduces the power oscillations around the peak power point which occurs with perturbation and observation algorithms. In addition, the total cost will decrease by removing the current sensor from the PV side. Finally, simulation results confirm the accuracy of the proposed method.

• Nuclear Engineering and Technology
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• v.38 no.8
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• pp.779-784
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• 2006

The design, manufacturing process, and first operating test of a high power RF source for a proton accelerator are described. A klystron amplifier system has been developed for operation at 700 MHz, 1 MW and is composed of a triode type electron gun, six cavities, an RF output window, a beam collector, and an electromagnet. The prototype klystron was constructed and tested at a reduced duty to produce the designed output RF power.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1323-1325
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• 2003

In field of Urban transit safely, It must be not only secured vehicle but also every areas like power, signal, communication, track, tunnel, operating facilities. Likewise it is very important not only hardware system like vehicles, facilities but also software system like action of engine driver, duty officer. In other to secure safety of hardware, soft ware, it is very important systemic process. In Korea, Many operating companies neglect to invest in safely and ignore technical development about safety because of management. Safely was considered in subway system and many studies were accomplished about safety in subway system in advanced county like U.K, USA. Hence, in this paper, Conditions and improvement of minimum considerable hardware and software are proposed for safe operation in Urban transit.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.3
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• pp.358-366
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• 2014

This paper proposes a quasi Z-source AC-AC converter with the low DC voltage distribution capability operating as a power electronic transformer. The proposed system has configuration that the input terminals of two quasi Z-source AC-AC converters are connected in parallel, also their output terminal are connected in series. Simple control method of duty ratio was proposed for the in phase buck-boost AC voltage mode and the DC output voltage control. DSP based experiment and PSIM simulation were performed. As a result, the PSIM simulation results were same with the measured results. By controlling the duty ratio under the condition of 100 [${\Omega}$] load, quasi Z-source AC-AC converter could buck and boost the AC output voltage in phase with the AC input voltage, and the same time, the constant DC voltage could be output without affecting the AC output characteristics. And, the DC output voltage 48[V] was constantly controlled in dynamic state in case while the load is suddenly changed ($50[\Omega]{\rightarrow}100[\Omega]$). From the above result, we could know that the quasi Z-source AC-AC converter can act as a power electronic transformer with a low DC voltage distribution capability.

• The Korean Journal of Emergency Medical Services
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• v.19 no.2
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• pp.99-115
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• 2015

Purpose: This study aimed to provide basic data for clinical training program development by analyzing the operating conditions and satisfaction in a clinical training program for 119 emergency medical technicians (EMTs) in South Korea. Methods: Data from 84 EMTs were collected on June 19, 2014. We administered a 64-item questionnaire about operating conditions and satisfaction in the clinical training program, and analyzed data (SPSS v 21.0). Results: The degree of performance in the field, importance of the item in the field, and level of difficulty were 3.36, 4.23, and 3.21, respectively. In the number of times that an item was directly performed according to the subjects' general characteristics a statistically difference in sex (p = .000), duty (p =.021), and total working time of trainees (p = .002). The subjects' total satisfaction score was 3.77. The difference in satisfaction according to the subjects' characteristics was a statistically significant in terms of sex (p = .016) and clinical training area (p = .005). Conclusion: A more efficient training system for hospital clinical training courses should be developed. The operation condition analyzed in this research may contribute to the improvement of the performance of EMTs.

• Korean Security Journal
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• no.29
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• pp.279-300
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• 2011

Countries recognize seriousness and concern about aviation terrorism, try to stamp out of it but aviation terrorism has been increasing in the world. Airport security is completely up to the result of security screening for passengers, check-in baggages and cargo at the check point. To complete effectively human and physical screening at the airport, it is essential to secure modernized screening equipment and specialized security screener, and airport security supervisor to supervising them. In this study, A survey conducted to find out the effect on screening equipment operating factors of airport security supervisor's individual attitude. The results of the study are as follow First, the duty view of airport security supervisor meaningfully affect expertise of screening equipment operating factors, satisfaction, reliability, and education and training, national point of view meaningfullly doesn't affect screening equipment operating factors. Second, the working condition effects on the education and training, if the working condition is getting better, intent to change occupation is getting lower. Third, duty stress meaningfully effects on the intent to change occupation, now airport security supervisor works in poor condition. Therefore, airport security supervisor needs to be prude of protecting the airport from the terrorism and various attacks and various kinds of aviation security regulations and procedures and comply with operating standards and keep the life of the country and its people, and needs to change awareness. And It is nessasary for government or airport authority or airline to prepare countermeasure for the improvement of their labor conditions.