• 한국산업융합학회 논문집
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• 제4권3호
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• pp.237-242
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• 2001

Ti-6Al-4V alloy can be obtained the stability of organization and product treasure, the evaluation of the cutting ability and the mechanical characteristics after the heat treatment of annealing, solution and aging. The difficulty in machining titanium alloy is how treat the heat generated during the process. Because the heat conductivity of titanium alloy is regardfully low, the heat generated during grinding is accumulated in workpiece. and it causes the increasing of grinding wheel grits' wear and makes the ground surface rough. So, these characteristics in grinding of titanium alloy will change the mechanical properties of the titanium alloy. From this study. the mechanical characteristics of annealed one and solution and aging one treated Ti-6Al-4V alloy after grinding was concerned with checking out the bending strength and hardness. For the result, both of bending strength and hardness were increased at the burned area on the surface. Roughness value was remarkably high at the table speed of 10m/min.

• 한국소음진동공학회논문집
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• 제25권8호
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• pp.546-552
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• 2015

In the previous study, the air flow noise around 1.6 k~1.8 kHz was analyzed, and could be reduced by machining a groove in the bore of compressor inlet in front of the main blades of a compressor wheel. It was proven that this groove was very effective for removing the noise without critical sacrifice of compressor performance, and in addition, it did not noticeably deteriorate vehicle performance, drivability and acceleration. It is interesting that the type of groove tried for 1.6~1.8 kHz noise reduction could be effective for another air flow noise, 4 k~6 kHz which is the 3rd order frequency range of turbocharger speed. This study tried various shapes of grooves for minimizing engine performance difference as well as reducing the 3rd order noise. Finally, it was shown that the groove should be round for the engine performance, and an optimal size exist for the noise and the engine performance.

• Restorative Dentistry and Endodontics
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• 제2권1호
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• pp.15-19
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• 1976

The author studied on the transfer of radioactive fluorine ($^{18}F$) to dental hard tissue through animal experiments which was divided into two groups. First group of rats were sacrified 1, 2, 5, 10 and 20 minutes after intraperitoneal injection. Second group were sacrified 1 and 3 minutes after topical application on anterior teeth. The teeth were removed and sectioned by means of abrasive wheel and polished on india stone as thick as about 50 microns. Autoradiograph picture was made by close contact of high-speed dental X-ray film on prepared specimen for 2 hours. The results of this study were as follows; 1) There was no evidence of transfer of $^{18}F$ on dental hard tissue on the cases of 1, 2 and 5 minutes survival after intraperitoneal injection. 2) Radioactive sodium fluorine incorporated to dental hard tissue was slight and diffuse at 10 minutes cases and significant incorporated picture was noticed at 20 minutes cases in intraperitoneal injection. 3) On topical application groups incorporated $^{18}F$ to enamel was traced clearly only on enamel surface at 1 minute cases and significant transfer into whole enamel was found at 3 minutes cases.

• 센서학회지
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• 제24권3호
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• pp.175-180
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• 2015

Worldwide, studies on intelligent vehicles for the convenience of drivers have been actively conducted as the number of cars has increased. However, vehicle convenience enabled by buttons lowers the concentration on driving and hence poses as a huge threat to the safety of the driver. The use of one of the convenient features, impaired driving auxiliary equipment, is limited because of its complex usage, and this device also hinders the front view of the driver. This paper proposes a vehicle-control device for controlling the convenient features as well as changes in speed and direction using gestures and motions of the driver. This device consists of an ultrasonic sensor for recognizing movement, an arduino for accepting signal control functions and servo and DC motors apply to various vehicle parts. Firstly, the vehicle-control device was designed using a 3D CAD program known as Solid-works based on the size of the steering wheel. Then, through simulations, a suitable length for minimizing the absorbent between ultrasonic sensors was confirmed using a program known as COMSOL Multiphysics. Finally, simulation results were verified through experiments, and the optimal size of the device was identified through the number of errors.

• 한국식품과학회지
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• 제30권1호
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• pp.118-124
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• 1998

Dehulled cowpea was microparticulated and coarse fractions and fine fractions were collected by air classification at air classifying wheel speed (ACWS) of 15,000 rpm, 12,000 rpm and 9,000 rpm, respectively. Protein content in fine fraction after air classification was 2 times higher than that of microparticulated cowpea, emulsion capacity was about 3 times than coarse fraction. The coarse fraction of the highest viscosity on the gelatinization properties were detected by amylograph, was C-3 (9,000 rpm coarse)fraction. The majority of microparticulated cowpea particles were oval shaped starch and the rest of them were indeterminate minute particles which had some sharp corners. As an application test, microparticulated cowpea and coarse fraction (C-3) were used for mook (Korea traditional starch jelly) preparation and the wet milled cowpea starch was compared as a control. Some impurities induced discoloring was detected by sensory evaluation but after washing, it made no difference in sensory scores between washed starch and the control cowpea mook. And also syneresis of washed cowpea was less than control. At the above result, it can be to recovery about 85% of cowpea starch using microparticulation/air classification technology.

• 한국주조공학회지
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• 제17권3호
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• pp.302-308
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• 1997

In spite of the fact that magnesium has low density and good machinability, its applications are restricted as a structural engineering material because of the poor strength, ductility, and corrosion resistance of the conventional ingot metallurgy alloys. Such properties can be improved by microstructural refinement via rapid solidification processing. In this study, Mg-5wt%Zn alloys have been produced as continuous strips by the melt overflow technique. In order to evaluate the influence of the cooling rate on the grain refinement and mechanical properties, seven different thickness strips were produced by means of controlling the speed of the cooling wheel. Then the microstructual observations were undertaken with the objective of evaluating the grain refinement as function of the cooling rate. The tremendous increase in hardness of Mg-Zn alloy was mainly due to the refinement of the grain structure by the effect of rapid solidification. The formation of intermetallic phases on the grain boundaries may have a positive effect on the corroion resistance. Therefore, despite competition from many other developments, the rapid solidification process emerges as a valuable method to develop superior and commercially acceptable magnesium alloys.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.78-83
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• 2009

In general, Light-hardening polymer was used UV nanoimprint technology. A light-hardening polymer was had the problem of poor hardness, durability. In order to overcome the problem of polymer, inter change optical glass. However glass is very manufacture and a lowering of standars transmittance. In order to glass recover was necessary polishing process. The process is magnetorheological fluids polishing. MR polishing has been developed as a new precision finishing technique to obtain a fine surface. Hence, Magnetorheological fluids has been used for micro polishing to get micro parts. This polishing process guarantees high polishing quality by controlling the fluid density electrically. The applied material in experiments is fused silica glass. Fused silica glass is widely used in the optical field because of high degree of purity. For MR polishing experiments, MR fluid was composed with DI-water, carbonyl iron and nano slurry ceria. The wheel speed and electric current were chosen as the variables for analyzing the characteristics of MR polishing process. Outstanding surface roughness of Ra=1.58nm was obtained on the fused silica glass specimen. And originally glass transmittance was recover on the fused silica glass.

• 대한의용생체공학회:의공학회지
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• 제17권1호
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• pp.1-10
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• 1996

In this paper, describe the automatic climbing wheelchair system use an articulated crawler mobile robot. This wheelchair system(call system) is composed of sensor detecting part and wireless communication part with PC. The sensor parts are consisted of sloping sensor and ultrasonic sensor part. The sloping sensor measures the sloping angle of system, and the ultrasonic sensor measures the distance of system's front wheel center from stair. PC will generate the operation data to climb up the stair using the measured data and make primitives for the system. At firsts This system transfer from sensor data to the PC. PC calculate the operation data to climb up the stair from the internal algorithm. We simulated the system in various stair angle slope($25^{\circ}$, $30^{\circ}$, $45^{\circ}$), and tested it on the real staircase with width 37cm, highlt 18cm, Angle $26^{\circ}$ . There were $0.350^{\circ}$ - $1.060^{\circ}$ Angle errors while climbing because adapted sensor has a precision $0.35^{\circ}$ in resolution. Finally, We implemented the sensor detecting part and the wireless communication park and practiced our system in 4cm/sec speed.

• 제어로봇시스템학회논문지
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• 제17권10호
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• pp.1006-1013
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• 2011

In this paper, we propose an optimal posture control law for an unmanned bicycle by deriving linear bicycle model from fully nonlinear differential equations. We calculate each equilibrium point of a bicycle under any given turning radius and angular speed of rear wheel. There is only one equilibrium point when a bicycle goes straight, while there are a lot of equilibrium points in case of turning. We present an optimal equilibrium point which makes the leaning input minimum when a bicycle is turning. As human riders give rolling torque by moving center of gravity of a body, many previous studies use a movable mass to move center of gravity like humans do. Instead we propose a propeller as a new leaning input which generates rolling torque. The propeller thrust input makes bicycle model simpler and removes input magnitude constraint unlike a movable mass. The proposed controller can hold optimal equilibrium points using both steering input and leaning input. The simulation results on linear control for circular motion are demonstrated to show the validity of the proposed approach.

• 한국기계가공학회지
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• 제13권4호
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• pp.69-74
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• 2014

A waste gate valve (WGV) assembly for a gasoline turbocharger is typically manufactured by means of precision casting. In this study, however, it was newly manufactured in a more innovative way, metal injection molding (MIM) using Inconel 713C alloy, and its performance was tested in a 1.6L direct injection gasoline engine by a thermal shock durability test that lasted 300 hours, after which the results were compared to those of a precision-cast WGV assembly with regard to the engine intake boost pressure, turbine wheel speed, and transient intake pressure. It was found that the two WGV assemblies showed similar performance levels throughout the durability test.