• Journal of Hydrogen and New Energy
• /
• v.20 no.5
• /
• pp.424-431
• /
• 2009

Treatment for water repellency on the carbon supports of GDL which composed a part of MEA has been suggested as a solution to prevent flooding. PTFE is a fluoropolymer that has hydrophobic property and a PTFE emulsion was selected as waterproof agent in this investigation. Carbon paper was coated by PTFE emulsion with different particle size of 5~500 nm and 3~$5\;{\mu}m$ as various concentration. PTFE coated carbon paper has difference in weight variation changed proportionally at PTFE concentration and coating times. Then gas permeability of the coated carbon paper with emulsion of 3~$5\;{\mu}m$ PTFE was changed vastly. Characteristics of carbon paper coated with different PTFE emulsion were analyzed by FE-SEM, FT-IR spcetroscopy and were evaluated by weight variations, gas permeability and water contact angle.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.10 no.2
• /
• pp.215-222
• /
• 1986

This paper presents the results of investigation, the aim of which was to predict theoretically the processes of thermodynamic cycle of M-combustion chamber type diesel engine. The combustion characteristics in cylinder are evaluated from the energy equation for an thermodynamic system in engine cylinder. In order to predict the combustion pressure in cylinder, the engine is divided in various control volumes. The simulation results of combustion characteristics show that the comparison of computed and measured values brings about the good coincidence.

• Journal of Magnetics
• /
• v.22 no.1
• /
• pp.78-84
• /
• 2017

This paper investigates the influence of mechanical energy storage on the interior permanent magnet synchronous machine (IPMSM) when it is operated in the generating mode. An IPMSM with six-poles and nine-slots employing concentrated coil winding type is considered as the analysis model, and a surface-mounted permanent magnet synchronous motor directly connected to a heavy wheel is applied as the mechanical energy storage system by using the moment of inertia. Based on the constructed experimental set-up with manufactured machines and power converters, the generated electrical energy is converted into the mechanical energy, and the electromagnetic filed characteristics of IPMSM are subsequently investigated by applying the measured phase current of IPMSM based on finite element method. Compared to the characteristics in a no-load condition, it is confirmed that the magnetic behavior, radial force, and power loss characteristics are highly influenced by the harmonics of the phase current due to the mechanical energy storage system.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.5
• /
• pp.905-910
• /
• 2009

For proper application and operation of a SFCL(Superconducting Fault Current Limiter) in distribution systems, the prior investigation of fundamental characteristics and its effects analysis to the systems are very important. A point of view in coordination with recloser in distribution systems, characteristic about quenching and recovering of SFCL should be studied. Especially, its detailed study of recovery characteristic is particularly important to avoid conflict between the SFCL and the recloser. In this paper, the resistive type SFCL and recloser, which used in distribution system, were implemented using EMTP/ATPDraw and MODELS language. To analyze the recovery characteristics of SFCL according to recloser operation in distribution systems, case studies have been simulated and investigated.

• Journal of environmental and Sanitary engineering
• /
• v.18 no.3 s.49
• /
• pp.48-58
• /
• 2003

To obtain the preliminary design data for combustion of paper sludges, decomposition characteristics and combustion kinetics of paper sludges reactor have been determined in a TGA reactor. Also, the combustion characteristics of paper sludges have been determined in a fluidized bed reactor. The data obtained from the TGA reactor indicate that dewatering of paper sludge is terminated at temperature below 130${\circ}$C. With heating rate of 20${\circ}$C/min, combustion is terminated at temperature below 340${\circ}$C .The combustion rate is found to be first order with respect to temperature and oxygen concentration. Activation energies for paper wastes are found to be 570, 700, 2600, 4600 Kcal/mole, respectively. The calcination conversions were investigated with the operating temperature and residence time. In this investigation, it was found that calcination conversion was affected by the operating temperature and residence time. The optimum conditions of operating temperature and mean residence time were 850${\circ}$C and 6 minutes of respectively.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.7
• /
• pp.1135-1140
• /
• 2008

Superconducting fault current limiters (SFCL) have been progressing due to the development of superconducting technology. The resistor type SFCL is one of the promising current limiting devices in power system for its effective operation. For proper application and operation of a SFCL, the prior investigation of fundamental characteristics and its effects to the distribution systems are needed. The most important current limiting behavior of a SFCL is dominated by quenching and recovery characteristics. In this paper, the resistive type SFCL was developed by using EMTP/ATPDraw and MODELS language. The operating characteristics and current limiting behaviors of the SFCL in distribution systems have been simulated and investigated.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.28 no.12
• /
• pp.1974-1981
• /
• 2004

This paper is concerned with the numerical investigation of the transfer characteristics of the landing impact force exerted on court sport shoes to the sport surface condition. The reaction force occurred by the impact between court sport shoes and sport surface is absorbed by shoes to some extent, but the remaining impact force is to transfer the human body from the sole of a foot. We consider four surface conditions, asphalt, urethane, clay and wood court surfaces. For the dynamic response analysis, we construct a coupled leg-shoes FEM model and create the multi-layered composite surface model. The numerical simulations are performed by an explicit nonlinear finite element method. Through the numerical experiments, we examine the transfer characteristics of the landing impact force to the surface condition.

• Tribology and Lubricants
• /
• v.18 no.2
• /
• pp.105-108
• /
• 2002

Specially designed grooved journal bearings are installed in the main coolant pump for SMART (System-integrated Modular Advanced ReacTor) to support radial load on the rotating shaft. The canned motor type main coolant pumps are arranged vertically on the reactor vessel and filled with circulating primary coolant which is pure water. The main coolant pump bearings are lubricated with this coolant without any other external lubricant supply. Because lubricating condition is too severe for this bearing to generate proper hydrodynamic film, investigation of lubrication characteristics of the journal bearing is important to satisfy life constraint of whole pump system, and the results will be applied to the analysis of dynamic characteristics of the shaft system. The bearing is made of silicon graphite which has self$.$lubricating effect. A lubrication analysis method is proposed for this vertically grooved journal bearing in the main coolant pump of SMART, and lubricational characteristics of the bearings are examined in this paper.

• Proceedings of the KSR Conference
• /
• 2009.05a
• /
• pp.1069-1077
• /
• 2009

For external noise prediction of railway vehicles, sophisticated individual source modelling as well as appropriate noise propagation model from the sources is necessary to ensure the accuracy of the predicted results and contributions of each equipment to the overall noise levels. Accurate and reasonable identification procedures of sound sources of equipment including source strength, directivity and positions installed in the train play an important role in a prediction model, since it is not easy to establish a simple model for the sources with a single rule due to the complexity of source characteristics of equipment in size and directivity pattern. This paper guidelines practical considerations for identification of noise sources in railway vehicles including typical source characteristics of several sub-systems that emits noise to the environment, particularly for electric multiple unit(EMU), and verify effectiveness of assumptions used in the modelling of equipment by measurement with a simple part. The predicted external noise level of a complete train using Exnoise, which was developed by Hyundai-Rotem and has been verified in the a lot of field-tests, incorporating source modelling considered in this paper shows close correlation with the measured ones.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 1995.04a
• /
• pp.65-92
• /
• 1995

The final aim of our research project is a study on assessment of automatic steering system of ships in open seas. In order to achieve this aim we need to know the characteristics of each component of the system and also to know the characteristics of disturbance to ship dynamcis. In this paper we provide calculation method of irregular disturbance to ships in autopilot navigation in open seas and also show calculation examples about two kinds of ship ore carrier and fishing boat. The disturbance consists of irregular wave and random wind, The disturbance is calculated as equivalent yaw angular velocity. Each spectrum and time history of disturbance are reasonably evaluated. Further investigation concerning to performance index of autopilot system and energy loss related to automatic course keeping will be dealt with in another paper,