• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.89.2-89.2
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• 2011

In automotive applicatons or water vehicles, the polymer electrolyte membrane fuel cell(PEMFC) stack is keep moving while their operation. Especially the inclination environment can take a effect to fuel cell stack perfromance, because this condition can cause a bad effect to water exhaust of fuel cell stack. In this study, a large scale stack(over 100kW power) is inclined upto 30 degree in lengthwise and crosswise using stack lift equipment. And the stack is operated in 10~100% load. No significant change has appeared in crosswise inclined condition and lenthwise low angle. But in lenthwise large angle tilting condition, the fuel cell performance has significantly decreased. And this performance decrease is aggravated in low load. An active water exhaust device is applied to the stack to prevent the performance decrease. And in lenthwise large angle tilting condition, this device cause a good effect to fuel cell stack performance.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1216-1221
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• 2003

The specimen materials used in this research is bimaterial. The static photoelastic experiment was applied to them. And then the specimens used in photoelastic experiment were fractured under static load. The static photoelastic hybrid method was introduced and it's validity had been assured. The static photoelastic hybrid method was applied to the Minimum Strain Energy Density Criterion, the Maximum Tangential Stress Criterion and Mode Mixity. Crack propagation criterion by the static photoelastic hybrid method was introduced and it was applied to the above various failure theories. Comparing the experimental initial angle of crack propagation with the theoretical initial angle of crack propagation from the various failure criterions. And then the optimal crack propagation criterion was suggested and it's validity was assured.

• Journal of the Ergonomics Society of Korea
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• v.25 no.4
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• pp.115-119
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• 2006

To investigate the effects of independent suspension technology(IST) of hiking boot on the stability and load of foot, eight participants performed medial and lateral drop landing from 33.4cm height and 85cm distance to uneven surface while wearing normal & IST hiking boots. For the stability of foot during the drop landing, the balance angle & suspension angle and rearfoot angle was analyzed using high-speed video analysis. Also kinetic analysis using the force plate and insole pressure measurement was conducted to analyze vertical & breaking ground reaction force and pressure distribution. Not only the balance angle & suspension angle but also rearfoot angle was improved with IST boots for lateral drop landing. These results indicate the IST boots may have the suspension function which keeps the foot to be stable during landing. However the IST boots did not show any effect for medial landing. This might be related to the hardness of medial part of outsole. Therefore the softer outsole of medial part could be recommended. Furthermore the impact force & breaking force and insole pressure were reduced with IST boot. These results means that IST boot has not only cushioning effect but also good grip effect. Therefore the hiking boots applied the independent suspension function may help to reduce fatigue and prevent injury such as ankle sprain in hiking on uneven surface.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.4
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• pp.563-571
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• 1989

The load distribution factor in the perforated square plate under concentrated load acting at arbitrary points through elastic media are calculated. For the calculation the perforated plate was converted into an orthotropic plate using the method suggested by J.B. Mahoney. In the process of the calculation the angle support at each corners was equivalent to a point support having equivalent stiffness. The deflections for the calculation of the load distribution factor were obtained using auxiliary plate extended in both directions of the plate and compared with the results from ANSYS calculations. After showing the validity of the current method, the calculation of the load distribution factor was performed. The result showed that the load distribution factor at the periphery of the plate is larger than that of in the central locations. This load distribution factor could be used for re-distribution of the applied load in more accurate analysis of the plate as well as it can be used in the analysis of the elastic media as the load factor.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.11
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• pp.737-742
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• 2015

This paper is designed to find out where power reaches the highest point as the load of solar cells varies. In addition, the current and power were measured when irradiation changes, and the correlation between current and power was investigated. On top of that, experiments were conducted with the light volume kept constant and with the incoming light angle changing in order to figure out the incoming light angle that produces the most power and to conduct analyses. It was ascertained that if the load increases, the current decreases and the voltage increases. Since the power of 0.9828[W] was the highest when measurements were done, it can be said that when a load of 30[%] is applied to the solar cells, they are the most efficient.

• Transactions of Materials Processing
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• v.19 no.5
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• pp.283-289
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• 2010

Extrusion process in the bulk material for fabrication of miniature helical gears has problems such as a high forming load and short tool life because the cross-section is complex and asymmetry. To overcome these problems, in this study, miniature helical gears were fabricated by Zn-22Al powder hot extrusion. The included die angle for minimum extrusion load and improving die filling was determined by FE-simulation. The Zn-22Al spheroidal powder produced by gasatomization were compacted and sintered for extrusion experiment. The dimension of helical-gear is 0.3mm in module, 3.35mm in pitch diameter, $15^{\circ}$ in helix angle and the number of teeth is 12. All of the extrusion experiments were performed with internal helical gear die which was machined by precision electric discharge machining using the electrode. The experiment was conducted at $190^{\circ}C$ to $310^{\circ}C$ to obtain extrusive and mechanical properties. The extruded helical gears were analyzed through extrusion load, Vickers hardness and SEM images for each extrusion temperature. The powder hot extrusion process was successfully applied to fabricate a miniature helical gear.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.751-758
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• 2001

Exergy concept is applied to the analysis of part-load performance of gas turbine engine. Exergy is a useful tool to find the source of irreversibility in thermal system. In this study, details of the performance characteristics of a heavy-duty gas turbine, l50MW-class GE 7FA model, are described by theoretical investigations with exergy analysis. Result shows that exergy destruction rate of gas turbine increases with decreased load, which means increase of irreversibility. Also, it is found that variations of IGV angle and amount of cooling air for turbine blades are closely related to the inefficiencies of compressor and turbine, respectively.

• Journal of Aerospace System Engineering
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• v.9 no.3
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• pp.23-30
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• 2015

In this study, a transient structural load analysis system was constructed to calculate the applied load on the suspension equipment corresponding to the aircraft flight conditions based on military specifications. Aircraft flight data (altitude, velocity, acceleration, angle of attack and etc. at aircraft center of gravity) were used as input parameters and the calculated load of the suspension equipment at wings on the left and right side was printed out for the structural load analysis. As a calculation procedure, first of all, load analysis was carried out at the center of gravity of the external store, Secondly, a trial reaction force analysis was conducted on hook and swaybrace of suspension equipment. All procedure of calculations was programed to analyze the structural load automatically. To verify the numerical results, structural load analysis using the experimental flight data was performed.

• Journal of Technologic Dentistry
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• v.37 no.3
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• pp.115-120
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• 2015

Purpose: The purpose of this study is a finite element analysis of supporting bone according to custom abutment angle. Methods: Implant fixture was selected with a diameter of 4 mm and the length of 13 mm. The fixture and abutment was designed by a combination of the abutment screw clamping force to produce a custom abutment model of $0^{\circ}$, $15^{\circ}$, $25^{\circ}$ and $35^{\circ}$. The loading condition of 176 N was applied to the lingual surface of the crown, near to the incisor edge, and horizontal load. An oblique load of $90^{\circ}$ was applied long axis of the implant fixture analyze the stress of supporting bone. Results: The result of mechanical analysis was observed that the supporting bone stress analysis of the horizontal load, the von Mises stress values (MPa) are given in the order of TH00 (432.6) > TH25 (418.0) > TH15 (417.4) > TH35 (415.8), the oblique load, the von Mises stress values are given in the order of TO00 (459.3) > TO15 (399.6) > TO25 (374.8) > TO35 (343.4) Conclusion: The $35^{\circ}$ abutment over the current clinical tolerance limits will be available for clinical application.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.325-328
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• 2006

This study analyzed the fluid state around a container crane according to a wind direction when a wind load was applied to a container crane. The container crane for this research is a model of a 50-ton class used broadly in the current ports. The dimension of an external fluid field is $500m{\times}200m$. This study considered the change of a wind velocity according to an altitude in a criterion of a wind velocity, 50m/s, applying a power series law. An incident angle applied to an interval of 30 degrees in $0^{\circ}C$ ${\sim}$ $180^{\circ}C$ and this study carried out a computation fluid dynamics using a CFX 10. In this study, we indicate the wind pressure and coefficient according to the height and section figure of each member. In addition, we suggest the wind load according to a wind direction.