• Transactions of the Korean hydrogen and new energy society
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• v.16 no.1
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• pp.66-73
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• 2005

Hydrogen linear power system is estimated as the next generation power system which can obtain a performance as same as fuel cell. In order to develop Hydrogen combustion power system with high thermal efficiency, it is very important to understand the basic characteristics of hydrogen combustion and establish combustion stabilization technique of its system. In this study, RICEM(Rapid Intake Compression Expansion Machine) for researching of hydrogen combustion linear power system was manufactured and evaluated, and the basic characteristics of linear RICEM were analyzed.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.5
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• pp.78-84
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• 2001

The translation system is made up of springs, masses and a dashpot. This precise piece of equipment is controlled electro-mechanically by a motor and operating program. The control strategy of the system can be changed by spring stiffness, change of mass, and the damping coefficient of the dashpot. This system proves the necessity and effect of a closed loop control. In this paper, PD control experiments were implemented for the translation system. When the north falter was added on the PD controller, we compared the response characteristics of the two systems. The state feedback controller minimized scalar control gains and the resulting response characteristics of the system were studied using the LQR design. Finally, we improved the response characteristics of the translation system which are rising time, settling time, steady state error, and overshoot LQR was better as compared with PD control.

• Tribology and Lubricants
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• v.12 no.4
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• pp.43-51
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• 1996

Rapid increase of refrigeration & air-conditioning system (r & a system) in modem industries brings attention to the urgency of research & development as a core technology in the area. And it is required to the compatibility problem of r & a system to alternative refrigerant for the protection of environment. Then, it is requested to study the lubrication characteristics of refrigerant compressor which is the core technology in the r & a system. The study of lubrication characteristics in the critical sliding component is essential for the design of refrigerant compressor. Therefore, theoretical investigation of the lubrication characteristics of rotary compressor for r & a system is studied. The Runge-Kutta method is used for the analysis of the behavior of rolling piston in the rotary compressor. The results show that the rotating speed of shaft and the discharge pressure have an important effect upon the angular velocity of the rolling piston. This results give important basic data for the further lubrication analysis and design of the rotary compressor.

• The Journal of Information Systems
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• v.25 no.4
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• pp.163-179
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• 2016

Purpose This study investigates the associations between SNS fatigue and stress of smartphone SNS, with SNS characteristics. The study focuses on two types of SNS characteristics: information and systems characteristics. We examine SNS stress factors that includes the communication and system overload. Design/methodology/approach To test the proposed hypotheses, the study conducted structural equation modeling with Smart PLS 3.0. The study conducted A sample of 286 participants was collected from SNS users. Findings The results indicated that the information relevance in the information characteristics had an effect on the communication overload, but it had not an effect on the system overload. The information accuracy had an effect on the communication and system overload. The app pace of change influenced the communication and system overload, but the app complexity influenced the system overload. Finally, the SNS stress showed significant relationship with SNS fatigue. The academic and managerial implications were discussed based on the this results.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.1
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• pp.37-42
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• 2009

This paper describes the fuel oil characteristics of mulching waste vinyl by indirect heating emulsion system. For the emulsion experiment of waste vinyl, the system is composed of melting furnace, the 1th pyrolysis furnace, and the 2nd pyrolysis furnace. The mulching waste vinyl is used for the fuel oil characteristics analysis of mulching waste vinyl. The refined oil, gasoline, and diesel oil are extracted and quantified to analysis the fuel oil characteristics. From the results of experiments, it has been shown that the production of fuel oil from mulching waste vinyl is possible using the emulsion system.

• The Journal of the Acoustical Society of Korea
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• v.1 no.1
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• pp.82-91
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• 1982

To analyze the characteristics of engine exhaust mufflers by the acoustic theory is necessary for understanding the action of mufflers and for designing the mufflers. In many cases, the " Transmission Loss" is used in the analysis, but TL is not suitable for above purposes. In this paper the characteristics of the mufflers is analyzed by means of the four terminal constants of whole muffler system. After some approximation, the characteristics of engine exhaust mufflers is shown by the "D" in the four terminal constants. 20log│D│ can be easily constructed with the characteristics of each element of the muffler system. The analysis is done under the conditions of no loss and no gas-flow, so the result is approximate. But it is very useful for understanding the characteristics of the muffler system or each element of the system and for designing the muffler system.

• Journal of the Korean Society for Railway
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• v.9 no.1 s.32
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• pp.18-22
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• 2006

The dynamic characteristics of the current collection system are investigated by conducting a test run in which signals from accelerometers and load cells attached to the various parts of the pantograph are analyzed in both the time and frequency domains. The dynamic characteristics of the current collection system are found to be strongly influenced by the train speed; the fluctuation in the pantograph motion increases in direct proportion to the train speed. There exist two major fequency components in the pantograph motion related to the current collection, a speed-dependent component arising from the train traversing a span of the catenary, and a speed-independent component related to the pantograph resonant frequency. The train acceleration is also found to exert strong influence on the current collection system characteristics. The effect of the train motion is found to be stronger on the speed-dependent frequency component than on the speed-independent one.

• Journal of Biosystems Engineering
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• v.28 no.2
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• pp.117-126
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• 2003

This study was conducted to develop precision control system fur cold storage facility that could offer safe storage environment for green grocery. For that reason of neuro-fuzzy control system with learning ability algorithm and single chip neuro-fuzzy micro controller was developed for cold storage facility. Dynamic characteristics and hunting of neuro-fuzzy control system were far superior to on-off and fuzzy control system. Dynamic characteristics of temperature were faster than on-off control system by 1,555 seconds(123% faster) and fuzzy control system by 460 seconds(36.4% faster). When system was arrived at steady state. hunting was ${\pm}$0.5$^{\circ}C$ in on-off control system, ${\pm}$0.4$^{\circ}C$ in fuzzy control system, and ${\pm}$0.3$^{\circ}C$ in neuro-fuzzy control system. Hunting of humidity and wind velocity was also controlled precisely by 70 to 72.5% and 1m/s For storage experiment with onion, characteristics of neuro-fuzzy control system were tested. Dynamic characteristics of neuro-fuzzy control system made cold storage facility conducted precooling ability and minimized hunting.

• Journal of Biosystems Engineering
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• v.34 no.3
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• pp.161-166
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• 2009

This study was conducted to investigate the growth characteristics of cherry tomatoes in greenhouse using far infrared heating system. The far infrared greenhouse heating systems were installed in two ways on the greenhouse side wall and at the greenhouse ceiling. The heating characteristics of far infrared heating system were analyzed by investigating the heating load, internal temperature, energy consumption, growth characteristics and quality evaluation. The results were compared with heated air heating system using kerosene. The results showed that tomatoes grown in the greenhouse with the far infrared heating system had relatively better plant height, leaf length, leaf width, stem diameter than ones from the greenhouse with hot air heating system and both heating methods had no significant difference on Cherry tomato sugar contents. At the same time, the far infrared heating system reduced heating cost from 34.5 to 41.4% on comparing with hot air heating system.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.521-525
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• 2009

Solar, as an ideal renewable energy, has inexhaustible, clean and safe characteristics. However, solar energy is an extreme intermittent and inconstant energy source. In order to improve the photovoltaic system efficiency and utilize the solar energy more fully, and the DC current vary with the irradiation, it is necessary to study the characteristics of photovoltaic I-V according to the external factors. This paper presents the analysis of characteristics of photovoltaic I-V according to the irradiation. The results show that the DC current of the photovoltaic system are increased along with the increasing values of irradiation.