• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.164-167
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• 2002

The general dicing process cuts a semiconductor wafer to lengthwise and crosswise direction by using a rotating circular diamond blade. But inferior goods are made under the influence of several parameters in dicing process such as blade, wafer, cutting water and cutting conditions. Moreover we can not applicable this dicing method to GaN wafer, because the GaN wafer is harder than the other wafer such as SiO$_2$, GaAs, CaAsP, and AlCaAs. In order to overcome this problem, development of a new dicing process and determination of dicing parameters are necessary. This paper describes determination of several parameters - scribing depth, scribing force, scriber inclined angle, scribing speed, and factor for scriber replacement - for a new dicing machine using scriber.

• Tribology and Lubricants
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• 제29권3호
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• pp.186-191
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• 2013

Hydraulic systems are used to transform mechanical energy into fluid energy and vice versa. They are widely applied in various industries; e.g., they are used in automobiles, public works, rockets, machine tools, heavy construction equipment, and airplanes. Hydraulic pumps are used to transform the energy in these systems. In this study, with the basic operation principles as a starting point, I attempted to clarify how the shape of a slipper affects the lubrication characteristics under practical conditions. A swashplate with a tilt angle of zero and capable of rotating motion was used, along with other devices. A slipper was located at 45 mm eccentricity from the center of the swashplate. The results of this experiment indicated that the shape of the bottom surface of a slipper affects the load capacity, leakage flow, and lubrication characteristics and that the slipper is one of the most important parts for improving the pump efficiency.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2004년도 Proceedings of 2004 Korea-Japan Joint Seminar on Particle Image Velocimetry
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• pp.15-23
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• 2004

The present study is aimed to achieve dynamic visualization from the in-house 3-D stereoscopic PIV to represent quantitative flow information such as time-resolved 3-D velocity distribution, vorticity, turbulent intensity or Reynolds stresses and so on. One of the application of the present study is Leading edge extension(LEX) flow appearing on modern delta wing aircraft. The other is mixing flow in stirring tank used in industry field. LEX in a highly swept shape applied to a delta wing features the modern air-fighters. The LEX vortices generated upon the upper surface of the wing at high angle of attack enhance the lift force of the delta wing by way of increased negative suction pressure over the surfaces. The present method resolves also the complicated flow patterns of two type impellers rotating in stirring vessel. Flow quantities such as three velocity vector components, vorticity and other flow information can be easily visualized via the 3D time-resolved post-processing visualization. And it makes the easy understanding of the unsteady flow characteristics of the typical industrial mixers.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.283-286
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• 1994

A speed control system of the induction motor drives by the load commutated current source inverter is studied in this paper. In general, since the rotating equipments such as pumps, fans and blowers do not require necessarily the accurate speed control performance, a voltage control and a speed sensorless vector control systems are mainly used for this application. In this paper, a new control scheme which has better performance than the voltage control system and simpler control structures than the vector control system is presented. This new proposed method controls the angle of the current vector using the relationship between the inverter output voltage and current, as well as uses the simple method to compensate the effect of the output capacitors.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.2053-2058
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• 2008

Extruded aluminium panels have been widely used for railway vehicle structures because of their light specific weight and other merit. In the past, GMAW (Gas Metal Arc Welding) and GTAW (Gas Tungsten Arc Welding) were mainly used to join aluminium panels. But recently friction stir welding (FSW) is widely used. due to its lots of advantage. In this study aluminium A6005-T6 which are used for car body structures was chosen. The influence of main parameters such as : pin rotating speed, welding speed, shoulder diameter, pin length and tilting angle on mechanical properties was examined. Optical microscope observation, micro hardness test and tensile test were carried out. Tensile strength of the stir welded plates is 74% of that of the base material.

• 동력기계공학회지
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• 제4권1호
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• pp.60-67
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• 2000

As the speed of rotating machines increases and also their weight decreases, the coupling between lateral and torsional vibrations must be considered. In the past, rotordynamics and geardynamics have tended to treat the lateral and torsional vibrations of the system elements as separate and decoupled mechanisms. In the paper, the coupled lateral-torsional free and forced vibration of rotors trained by gears is analyzed using finite element method. Also the complicated variation of the meshing stiffness as a function of contact point along the line of action is estimated correctly. The gear mesh model is assumed to be linear with constant average mesh stiffness.

• 반도체디스플레이기술학회지
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• 제2권4호
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• pp.23-26
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• 2003

The general users find difficulties in using ellipsometers. Thus, the object of this study is to construct an ellipsometer with simple operation principle. We developed an ellipsometer which does not require alignment and calibration before measuring sample. A basis structure model after rotating a compensator spectroscopic ellipsometry, the fixed incidence angle at $70^{\circ}$. This ellipsometer does not demand calibration, because the plane of incidence is not changed due to the novel sample holder structure. The results for various standard samples were compared with those from conventional RCSE to test the performance of this instrument. Also repeated measurements were performed to test the precision of the calibration coefficient in a plane of incidence fixed.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.285-288
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• 2007

In the recent years the using of low-density material such as high-strength Al alloy on the various industries is becoming light-weight. High strength and hollow Al alloy is good material for stiffness and recycling. Therefore the advanced manufacturing technology with Al alloy is continuously required in many industrial fields. In this study simplified hallow rectangular section of Al alloy is analyzed by FE analysis. Bending stress is affected punching and rotating of wing-die. The analysis of press bending is preformed at first. The elastic recovery value of component and stress distribution acting from the result of the bending angle of three types were obtained. The designed precesses were analyzed by the commercial FE code, Deform-3D. Forming dies for each process were designed and prototypes were manufactured by the verified forming process. Some of the important features of design parameters in the press bending were reviewed.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.867-869
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• 2004

A smart blade conception has been proposed by the authors. With stretching-twisting coupling effect, the blade is twisted by centrifugal load or ambient temperature change. In this paper, the blades, made by three kinds of anti-symmetric laminates, are investigated by rotational tests. The results show the angle of smart blade tips increases in proportion to the 2nd power of a rotating speed and is well in agreement with the numerical results by FEM.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.333-336
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• 2006

The response of a reinforced concrete element under cyclic shear is characterized by the hysteretic loops of the shear stress-strain curves. Recent tests have shown that the orientation of steel grids in RC shear elements has a strong effect on the "pinching effect" and ductility in the post-yield hysteretic loops. In this paper, four RC elements are considered to study the effect of the steel grid orientation on "pinching effect" and ductility. The presence and absence of the pinching mechanism in the post-yield shear hysteretic loops are studied using the Rotating Angle Softened Truss Model (RA-STM) theory.