• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.6 s.99
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• pp.687-696
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• 2005

Acoustic power spectrum of the upstream and downstream sound field due to an isotropic frozen turbulent gust impinging on a cascade of flat plate airfoils are computed by using a analytic formulation derived from Smith's method, and Whitehead's LINSUB codes. A parametric study of the effects on sound power of the number of blades and turbulence length scale is performed with an emphasis on analyzing the characteristics of sound power spectrum. Through the comparison of the computed results of sound power, it is found that acoustic power spectrum from the 2-D cascade subject to a ingested turbulence can be categorized into two distinct regions. one is lower frequency region where some spectral components of turbulence do not contribute to the cut-on acoustic modes and therefore the effect of the cascade geometry is more dominant ; the other is higher frequency region where all of spectral components of turbulence make contributions to cut-on acoustic modes and thus acoustic power is approximately proportional to the blade number.

• Transactions of Materials Processing
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• v.22 no.2
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• pp.80-85
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• 2013

The surface integrity of micro-machined products affects the performance of products significantly. Micro-burrs resulting from micro-cutting degrades the surface quality. Therefore it is desired to eliminate them completely and many studies have been undertaken for this purpose. In this study, micro-end-milling was carried out on nickel alloy and brass materials commercially used for light guide plate mold in 3-D optical devices. After completing this micro-machining, the burr heights were measured with a microscope. Then, deburring was done on the machined edges using the MR jet polishing method. A jet angle of $0^{\circ}$ and deburring times of 1, 3, and 5 min. were chosen. It was found that burrs were completely eliminated after 5 min of MR fluid jet polishing.

• Journal of International Society for Simulation Surgery
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• v.3 no.2
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• pp.80-83
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• 2016

A 37-year-old male was assaulted and complained of severe periorbital swelling. Physical examination revealed that there were limitation of eyeball movement on upper gaze, diplopia, and hypoesthesia on the infraorbital nerve innervating region. Three-dimensional (3D) computed tomography (CT) of facial bone exhibited the fracture of orbital floor accompanying the significant amount of orbital contents' herniation extending to the far posterior part. To recover the orbital volume and restore orbital floor without threatening the optic nerve, preoperative simplified simulation was applied. The posterior margin of the fractured orbit was delineated with simulation technique using cross-linkage between the coronal and sagittal sections based on the referential axial view of the CT scans. Dissection, reduction of orbital contents, and insertion of the absorbable mesh plate molded after the prefabricated template by the simulation technique was performed. Extensive orbital floor defect was successfully reconstructed and there were no serious complications. The purpose of this report is to emphasize the necessity of preoperative simulation in case of restoring the extensive orbital floor defect.

• Journal of Power System Engineering
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• v.10 no.2
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• pp.29-35
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• 2006

Two-dimensional numerical simulation has been performed to investigate mixed convection heat transfer between inclined parallel plates with bottom-heated and top-cooled uniformly. The ratio of parallel plate length to height is 9.33, Prandtl number is 909(that of silicone oil at 298K) and Rayleigh number is 8600. In the ranges of the Reynolds number Re from 0 to 1.8 and the angle of inclination ${\theta}$ from 0 to 90 degree. The governing equations are discretized using the finite volume method. In this study, the effects of the Reynolds number, the angle of inclination, and the local and mean Nusselt numbers are presented and discussed. It is found that the periodic flow of mixed convection between inclined parallel plates is shown at $0^{\circ}{\leq}\;{\theta}<30^{\circ},\;Re<0.063$, and the flow pattern can be classified into three patterns which depend on Reynolds number and the angle of inclination. The minimum average Nusselt numbers occur at Re=0.05 regardless of the angle of inclination.

• Journal of Power System Engineering
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• v.13 no.5
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• pp.67-75
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• 2009

Recently, the higher capacity waste heat recovery PDC clean ventilation system has a tendency which is increasing due to the excellent energy reduction in factory, big building, and so on. This system was developed to complement the room environment which is deteriorated. However, the researches and technologies about this system were not well studied. Specially, the characteristic for heat exchanger element used to this system were not well known. Therefore, this study was carried out to evaluate the mechanical properties of the heat exchanger element as the core parts compose of this system. From results, tensile strength and elongation of the plate type heat exchanger element had about 10.11~14.32 kgf/$mm^2$ and 8.0~16.2%, respectively.

• Transactions of Materials Processing
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• v.15 no.2 s.83
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• pp.118-125
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• 2006

API steel is used for line-pipe to transport the oil and natural gas. As the recent trends in the development of API steel are towards the use of larger diameter and thicker plate, many researches have been studied to achieve higher strength, higher toughness and lower yield ratio in API steel. However, the strength of API steel after pipe forming is changed depending on the competition of the Bauschinger effect and work hardening which are affected by the strain history during pipe forming process. So, the purpose of this study is to investigate the influence of microstructure on the Bauschinger effect for API steel. To change the microstructure of API steel we have changed the hot rolling condition and the amounts of V and Cu addition. The compression-tensile test and the microstructure observation by OM and TEM were conducted to investigate the yield strength drop and the correlation between the Bauschinger effect and microstructure of API steel. The experimental results show that the increase of polygonal ferrites volume fraction increases the Baushcinger effect due to the back stress which comes from the increase of mobile dislocation density at polygonal ferrite interior during the compressive deformation. The hot rolling condition was more effective on the Bauschinger effect in API steel than the small amount of V and Cu addition.

• The Korean Journal of Pain
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• v.8 no.1
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• pp.18-24
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• 1995

We produced the causalgiform pain by the tight ligation of L5 and L6 spinal nerves in the adult rats. To evalute the effect of Ketamine -noncompetitive NMDA (N-methyl-D aspartate) antagoinst- on the causalgiform pain, we tested the changes of; withdrawal sensitivity to the innocuous mechanical stimulation of Von Frey hair 2.35 g(mechanical allodynia); withdrawal frequency to the cold stimulation of acetone (cold allodynia); and total withdrawal time (second) to the cold ($4^{\circ}C$) plate stimulation (cold hyperalgesia) after the administration of 1 mg, 3 mg, 10 mg/kg ketamine. The results were as follows: 1) Cold hyperalgesia was significantly reduced (p<0.05) by 1 mg, 3mg, 01 mg/kg ketamine. 2) Cold allodynia and mechanical allodynia was significantly reduced (p<0.05) by 10 mg/kg ketamine. Above results suggest a therapeutic utility of ketamine in treatment of causalgia - especially, cold hyperalgesia.

• Journal of Ocean Engineering and Technology
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• v.27 no.2
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• pp.87-92
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• 2013

The variation in the course keeping ability in relation to rudder type is investigated using simulations with 3 different types of rudders (a normal rudder, normal rudder with a plate, and Schilling rudder) under wave conditions. The simulation is developed based on an MMG model with Kijima's regression model, along with the data from Son's experiments and Kose's experiments. A 3-D source distribution method is applied to calculate the source of the external wave forces for the simulation. The coefficients of an autopilot controller that may affect the course keeping ability are also estimated from the simulations with the different rudders. The course keeping ability is evaluated by comparing the forward distances while the ships are simulated with the rudders and autopilot controller.

• Journal of the Korean Vacuum Society
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• v.5 no.1
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• pp.25-32
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• 1996

An ERD-TOF system is constructed for the nondestructive depth profiling of light elements in thin films in the range of several thousand angstroms. The particles, recoiled by 10 $MeV^{35}Cl$ projectiles, were detected by a Time-Of-Flight spectrometer composed of a MCP (Micro Channel Plate) and a SSB (Silicon Surface Barrier) detector. A two parameter data acquisition system composed of two PC's was constructed for registering simultaneous time and energy signals. A $Si_3N_4$/poly-Si/$SiO_2$/Si sample was anlayzed and the result is compared with RBS. The detection limit, maximum probable depth and depth resolution for light elements in silicon are about $4\times10^{14}atoms/\textrm{cm}^2$, 5, 000$\AA$ and 100$\AA$, respectively.

• Journal of Welding and Joining
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• v.7 no.3
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• pp.44-54
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• 1989

This study was undertaken to evaluate the allowable welding heat input range for high strength steels manufactured by various processes and to compare the weldability of TMCP steel for high heat input welding with that of conventional Ti-added normalized steel. The allowable welding heat input ranges for conventional 50kg/$mm^2$ steel to guarantee D or E grade of ship structural steel were below 150 and 80kJ/cm respectively. Such a limit in welding heat input was closely related with the formation of undesirable microstructures, such as grain boundary ferrite and ferrite side plate in the coarse grain HAZ. In case of 60 and 80kg/$mm^2$ quenched and tempered steels, for securing toughness in weldments over toughness requirements for base metal, each welding heat input had to be restricted below 60 and 40kJ/cm, that was mainly due to coarsened polygonal ferrite in weld metal and lower temperature transformation products in coarse grain HAZ. The TMCP steel could be appropriate as a grade E ship hull steel up to 200kJ/cm, but the Ti-added normalized steel could be applied only below 130kJ/cm under the same rule. This difference was partly owing to whether uniform and fine intragranular ferrite microstructure was well developed in HAZ or not.