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Distribution systems are mostly composed of radial structures, which are susceptible to an increased variability and complexity of system operation due to frequent line changes during operation. When multiple changes in distribution lines occur simultaneously, the relative positions of protective devices also change. The existing protection coordination method of distribution lines is configured by considering the operation characteristics and coordination time interval (CTI) of all protective devices in series from the substation to the terminal load. Therefore, the protection coordination algorithm needs to be redesigned whenever a line is changed or a protective device is added to the distribution line for which the existing protection coordination algorithm has been set. In addition, existing protection coordination methods require complex calculations and procedures, which are subject to human errors and are less feasible for responding in real-time to changes in the distribution system. In this paper, we propose the adaptive time–current curve (TCC) method by selecting the time dial setting (TDS) and minimum response time (MRT) of individual protective devices in accordance with the relative distance based on the linear optimization technique. Using PSCAD/EMTDC, a power system analysis program, the minimum operating current and the fault current of each protective device are obtained, and the proposed protection coordination algorithm is verified according to the series configuration relationship of the protective devices. Finally, the proposed method is applied to an actual distribution line to verify the improvement over the existing protection coordination.

Temporal bone trauma can cause hearing loss and in case of prolonged conductive hearing loss, traumatic ossicular injury should be considered. Separation of the incudostapedial joint is the most common lesion, and stapediovestibular dislocation is relatively rare but can easily cause perilymphatic fistula. Here, we report a very rare case of external stapediovestibular dislocation after trauma, ending up with successful surgical outcome. A 27-year-old man with non-progressive hearing loss on the right side since childhood visited the clinic. Audiogram showed a conductive hearing loss with air-bone gap of 55 dB on the right side. Temporal bone CT revealed the disruption of ossicular chain. An exploratory tympanotomy identified multiple ossicular disruptions including external stapediovestibular dislocation with shiny fibrous membrane sealing the oval window. Ossicular chain reconstruction was performed using the total ossicular replacement prosthesis of titanium. A postoperative audiogram showed a recovery of air-bone gap less than 10 dB. To the best of our knowledge, this is the first case of external long-standing stapediovestibular dislocation, with oval window completely sealed with fibrous membrane, ending up with successful hearing recovery by surgery. This case would help dealing with such condition which can be encountered in the clinic.

The air-conditioning system operated by the variable swash plate compressor which is used in most engine vehicle is a convenient device that allows the user to comfortably maintain the temperature inside the vehicle properly. However, since the compressor is operated by the engine, the high efficiency of air-conditioning system to reduce fuel consumption and the compressor durability improvement on the high speed and high load conditions has been becoming the important issue. In this paper, the research of the compressor oil separator has been carried out to improve the system efficiency and to guarantee the compressor durability. The compressor circulates refrigerant and oil to the system, where the Oil Circulation Ratio (OCR) is an important factor affecting system performance and compressor lifetime. Therefore, we propose a method to minimize system performance degradation and to guarantee compressor durability by optimizing the oil separation function inside the compressor. For this study, the basic principles of oil separation are analyzed mathematically and optimized oil separator in the compressor has been suggested. Then, the optimized oil separator function is verified in the actual car air conditioning system.

Experimental research about the oil-gas separator was conducted in order to improve the performance of electric driven scroll compressors used in eco-friendly HEV/EVs. The compressor used in the tests was “back pressure” method electric driven scroll compressors using oil. To maintain adequate back pressure, an oil separator in the discharge chamber is required. It is inevitable that the refrigerant passing an oil separator inside a discharge chamber experiences a pressure drop. This pressure drop increases input power, resulting in some decrease of the COP of the compressor. Various parameters of the oil separator— the length of vortex finders; installation angle; and the inlet, outlet diameters— related to the pressure drop were considered. The installation angle and the outlet diameters had no significant effect on the pressure drop; however, a pressure drop decrease in relation to the length of the vortex finder and the inlet diameter was confirmed. As the vortex finder length decreased and the inlet diameter increased, the input power of the compressor is decreased about 4.12% and the COP is increased about 2.66% by the reduction of the pressure drop.

The main roles of the oil in scroll compressor are to lubricate the friction parts, and to reduce the compressor driving power and to improve the durability of the compressor consequently. However, it has another side that could make decrease the efficiency of the heat exchanger and whole air-conditioning system. In the case of compressor, if the oil is charged too much, the compressor driving power will be increased and the compressor overall efficiency will be decreased. Therefore, the initial charge amount of the oil in the compressor should be determined appropriately. This study has performed to optimize the initial charge amount of the oil on the electric driven scroll compressor for eco-friendly vehicles. We have used a electric driven scroll compressor has a back pressure chamber which make up of oil. About the various initial charge amount of the oil, The remaining oil was evaluated at each of steps of the complex durability test and each of conditions of performance test. The various initial charge amount of the oil had increased 20g at a time from 40g to 120g. Through the evaluation, the optimum amount of the Oil is determined by the back pressure. So we have found the optimum amount of Oil. Also the performance of a system is compared through pulldown test in the actual air conditioning system. We could get the optimal amount of oil which has the best performance in air conditioning system.