• Journal of Advanced Marine Engineering and Technology
• /
• v.33 no.5
• /
• pp.770-777
• /
• 2009

The energy depletion and the environmental pollution like global warming are worldwide issues. For correcting these problems there are many studies on new-renewable energy in Korea. A kind of new-renewable energy, PEMFC(Proton Exchange Membrane Fuel Cell) is a low temperature fuell cell and there are some cases of small craft or submarine adopted PEMFC system in maritime. PEMFC's performance is affected the operating conditions. Finding optimum operating conditions must be performed before adopting PEMFC to system. So in this study, we experiment about various operating conditions to apply 150W PEMFC stack for a model boat. And through the results, we find optimum operating conditions and study an effect of operating conditions to PEMFC.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2003.05a
• /
• pp.76-80
• /
• 2003

The procedure of finding operating conditions minimizing qualify loss is proposed with a real industry example. The procedure consists or major two parts - the selection or process variables critical to the response and He determination or operating conditions. The coefficients or ridge regression and the and stores or partial least squares are applied to select important process variables. Functional approach and Non-functional approach are used to find proper operating conditions of important process variables.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.1079-1080
• /
• 2011

This paper deals with the operating characteristics of induction motors with broken rotor bar, stator winding inter-turn short and their complex fault conditions. The considered operating characteristics are phase current, torque and speed. Since the operating characteristics of induction motors are directly related to their slip conditions, this paper built the experimental set to adjust the speed of induction motor with a permanent magnet synchronous generator connected to a load bank. From the various experimental results, it is shown that the faults do not highly affect on the operating characteristics of induction motors in low slip conditions, but the fault characteristics can be easily found in larger slip conditions.

• Journal of Power Electronics
• /
• v.19 no.5
• /
• pp.1142-1152
• /
• 2019

This paper presents a control method for reducing the current distortion in an indirect matrix converter (IMC) operating in boost mode under unbalanced input conditions. IMCs operating in boost mode are useful in distributed generation (DG) systems. They are connected with renewable energy systems (RESs) and the grid to transmit the power generated by the RES. However, under unbalanced voltage conditions of the RES, which is connected with the input stage of the IMC operating in boost mode, the input-output currents are distorted. In particular, the output current distortions cause a ripple of the power, which is transferred to the grid. This aggravates the reliability and stability of the DG system. Therefore, in this paper, a control method using positive/negative sequence voltages and currents is proposed for reducing the current distortion of both side in IMCs operating in boost mode. Simulation and experimental results have been presented to validate effectiveness of the proposed control method.

• Journal of the Korean Institute of Gas
• /
• v.7 no.4 s.21
• /
• pp.20-23
• /
• 2003

The analysis of reliabilities of process facilities often uses models based on the Weibull distribution. The parameters in these models are functions of operating conditions, and determined by experiments. Using these values, we calculate the reliability, mean time to failure, and standard deviation. The conventional method assumes that the operating condition is constant, and thus treats the model parameters as constants. In this paper, a reliability function is proposed which is applicable when the scale parameter is a function of time, and an analysis method based on this is also presented. A case study on a cooling fan resulted in a big difference from the conventional method to which the average operating conditions were applied. The proposed method is also applicable to other process facilities, and expected to effectively take into account the effects of changes in the operating conditions on the reliabilities of the facilities.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.484-485
• /
• 2008

A micro-grid (MG) is a new concept to aggregate distributed generations (DGs) and loads in a small area. The difference between MG and DG is that MG can supply power to loads even in islanding conditions. The magnitude of the fault current depending on interconnection between the MG and utility and the number of DGs in the MG. Therefore, the setting value of the OCR must be changed depending on operating conditions of the MG. This paper proposes the over-current relay considering operating conditions of the MG. In the proposed algorithm, the supervisory control and data acquisition decides the operating conditions of the MG and sends the proper setting values to each OCR. The performance of the algorithm was investigated in the case of the various operating conditions.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.51 no.11
• /
• pp.535-543
• /
• 2002

Modern power grids are becoming more and more stressed with the load demands increasing continually. Therefore large stressed power systems exhibit complicated dynamic behavior when subjected to small disturbance. Especially, it is needed to analyze special conditions which make small signal stability structure varied according to operating conditions. This paper shows that the relation between small signal stability structure varied according to operating conditions. This paper shows that the relation between small signal stability and operating conditions can be identified well using node-focus point and 1:1 resonance point. Also, the weak point which limits operating range is found by the analysis of resonance condition, and it is shown that reactive power compensation may solve the problem in the weak points. The proposed method is applied to test systems, and the results illustrate its capabilities.

• Transactions of the Korean hydrogen and new energy society
• /
• v.23 no.6
• /
• pp.604-611
• /
• 2012

For the commercialization of fuel cell powered vehicle, it is highly important to improve the performance and efficiency of an automotive polymer electrolyte membrane fuel cell (PEMFC) system. The performance and efficiency of PEMFC systems are significantly influenced by their operating conditions. Among these conditions, the system operating pressure is considered as the one of the main factors. In this study, to investigate the effects of operating pressure on the performance and efficiency of automotive PEMFC systems, two types of high-pressure operating PEMFC systems adopting two different compressors (i. e. different performance maps) are modeled by using MATLAB/Simulink environment. The PEMFC system efficiency and parasitic compressor power are mainly analyzed and compared for the two types of high-pressure operating PEMFC systems under the same system net power conditions. It is expected that this kind of study can contribute to provide basic insight into the operating strategies of high-pressure operating PEMFC systems for automotive use.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.22 no.12
• /
• pp.1755-1762
• /
• 1998

In order to minimize emission of polychlorinated dibenzo dioxins and polychlorinated dibenzo furans (PCDD/PCDFs) from municipal solid waste incinerators, it is important to maintain optimized operating conditions along with the system modification/improvement. Operating conditions of MSW incinerator make very complicated influence on formation of PCDD/PCDFs in each unit apparatus. For revealing these influences, concentrations of PCDD/PCDFs are measured from the stack and from the fly ash, while monitoring the plant operating conditions. The effects are grouped into 3 main categories, combustion conditions, de Novo synthesis effects, and adsorption/destruction effects in the flue gas treatment system. Interpretation of the results showed that de Novo synthesis effect, reformation by metalic catalyst, especially Cu in fly ash in the temperature range of $250{\sim}500^{\circ}C$, is found to influence most dominantly on the concentration of PCDD/PCDFs. A plausible mathmatical model for predicting concentration of PCDD/PCDFs is proposed, and discussed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.36 no.5
• /
• pp.474-481
• /
• 2023

This paper is an experimental study on the optimal operating conditions of direct charging type electrospray for particulate matter collection. To perform the research, a direct charging type electrospray visualization system was configured to photograph the spray shape of microdroplets, and experiments were performed with varying electrode distance, flow rate, and applied voltage, which are the main factors affecting the particulate matter collection efficacy. Through image processing, the total number of microdroplets according to each condition was analyzed, and the number of microdroplets with a diameter of 1.5 mm or less was confirmed. In addition, by calculating the number of microdroplets per power consumption according to the applied voltage, the optimal operating conditions were derived in terms of energy consumption efficacy, and the microdroplet size distribution was analyzed under the optimal operating conditions. As a result of the experiment, it was confirmed that the optimal operating condition was at a flow rate of 10 mL/min and a voltage of -20 kV in case of 5 mm electrode distance, and at a flow rate of 15 mL/min and a voltage of -30 kV in case of 100 mm electrode distance.