• Laser Solutions
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• v.18 no.3
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• pp.6-8
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• 2015

Finishing process includes deburring, polishing and edge radiusing. It improves the surface profile of specimen and eliminates the alien substance on surface. Deburring is the elimination process for debris of edges. Polishing lubricates surfaces by rubbing or chemical treatment. There are two types for electron finishing. The one is using pulse beam. The other is using the convergent and scanning electron beam. Pulse type device appropriates the large area process. But it does not control the beam dosage. Scanning type device has advantages for dosage control and edge deburring. We design the convergence and scan type. It has magnetic lenses for convergence and scan device for scanning beam. Magnetic lenses consist of convergent and objective lens. The lenses are designed by the specification(beam size and working distance). In this paper, we evaluate the convergence performance by pattern process. Also, we analysis the results and important factors for process. The important factors for process are beam size, pressure, stage speed and vacuum. These results will be utilized into systematizing pattern shape and the factors.

• Journal of the Korean Institute of Navigation
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• v.3 no.2
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• pp.21-30
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• 1979

Echo sounder and Doppler sonar are to theultra-sonic transducers for measuring the depth and the ship's speed respectively. To measure the depth and speed with a single transducer, it is required to control the ultra-sonic beam to optional direction. In the past, the direction of the transducer itself is varied, but such a method provoked much problems in the mechanical design of the equipment. This paper deals with the method to control beam direciton by the phase control of the plural arrangement of transducers, and the results are studied by a computer simulation. The remarkable results of the study is condensed as follows; 1. The greater the interval of arrangement between transducers, the sharper the radiation pattern is, but in this case, the level of undesired sidelobe is also increased. 2. The control of radiation pattern up to 60 degree can be achieved by an adequate arrangement of more than 10 transducers. 3. It is shown that a simultaneous measurement of both depth and speed can be achieved by alternating directivity of the pulse by the method proposed in this paper.

• The Journal of the Acoustical Society of Korea
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• v.24 no.3E
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• pp.115-122
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• 2005

Two twin microphones may produce particular patterns of binaural directivity by time delays between twin microphones. The boundary element method (BEM) was used for the simulation of the sound pressure field around the head model in order to quantify the acoustic head effect. The sound pressure onto the microphone was calculated by the BEM to an incident sound pressure. Then a planar directivity pattern was formed by four sound pressure signals from four microphones. The optimal binaural directivity pattern may be achieved by adjusting time delays at each frequency while maintaining the forward beam pattern is relatively bigger than the backward beam pattern.

• Progress in Medical Physics
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• v.28 no.3
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• pp.129-133
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• 2017

The machine log files recorded by a scanning control unit in proton beam therapy system have been studied to be used as a quality assurance method of scanning beam deliveries. The accuracy of the data in the log files have been evaluated with a standard calibration beam scan pattern. The proton beam scan pattern has been delivered on a gafchromic film located at the isocenter plane of the proton beam treatment nozzle and found to agree within ${\pm}1.0mm$. The machine data accumulated for the scanning beam proton therapy of five different cases have been analyzed using a statistical method to estimate any systematic error in the data. The high-precision scanning beam log files in line scanning proton therapy system have been validated to be used for off-line scanning beam monitoring and thus as a patient-specific quality assurance method. The use of the machine log files for patient-specific quality assurance would simplify the quality assurance procedure with accurate scanning beam data.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.2 s.25
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• pp.96-102
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• 2006

In this paper, the design, construction and basic characteristics of an electronically adaptive array antenna for the GPS receiver is described. The susceptibility of the GPS signals to the interference is of concern to the GPS user community. Because of the low received power of the GPS signals, outages can easily occur due to the unintentional interference and the easily obtainable low cost GPS jammer denying access to the GPS signals. We propose a technique of the adaptive array antenna that detects the GPS interference sources and controls the null beam pattern only toward the jamming sources to acquire GPS navigation data after acquisition and tracking of the GPS signals.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.12
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• pp.1067-1071
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• 2013

A 3D visual sensing method using a laser structured beam is presented for robotic tracking applications in a simple and reliable manner. A cylindrical shaped laser structured beam is proposed to measure the pose and position of the target surface. When the proposed laser beam intersects on the surface along the target trajectory, an elliptic pattern is generated. Its ellipse parameters can be induced mathematically by the geometrical relationship of the sensor coordinate and target coordinate. The depth and orientation of the target surface are directly determined by the ellipse parameters. In particular, two discontinuous points on the ellipse pattern, induced by seam trajectory, indicate mathematically the 3D direction for robotic tracking. To investigate the performance of this method, experiments with a 6 axis robot system are conducted on two different types of seam trajectories. The results show that this method is very suitable for robot seam tracking applications due to its excellence in accuracy and efficiency.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.816-819
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• 2000

Recently the styrofoam has been used fur material of press die pattern. The object of this research is to develope an automated laser system for manufacture of press die pattern which depends chiefly on handwork during its process. After converting 3-D CAD model into cross-sectional shape information, the unnecessary part of the section is vapored away by laser. The depth and width of cut are mainly under the control of laser power and beam feed rate. The optimum manufacturing conditions are obtained by preliminary experiments. It is necessary fur precise styrofoam pattern manufacturing to develope laser system which has sufficient motion accuracy and program or beam path generation and automatic control of this system.

• Journal of the Semiconductor & Display Technology
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• v.3 no.2
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• pp.5-9
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• 2004

Microcircuit fabrication requires precise control of impurities in tiny regions of the silicon. These regions must be interconnected to create components and VLSI circuits. The patterns to define such regions are created by lithographic processes. In order to image features smaller than 70 nm, it is necessary to employ non-optical technology (or next generation lithography: NGL). One such NGL is extreme ultra-violet lithography (EUVL). EUVL transmits the pattern on the wafer surface after reflecting ultra-violet through mask pattern. If particles exist on the blank mask, it can't transmit the accurate pattern on the wafer and decrease the reflectivity. It is important to care the blank mask. We removed the particles on the wafer using focused ion beam (FIB). During removal, FIB beam caused damage the multi layer mask and it decreased the reflectivity. The relationship between particle removal and reflectivity is examined: i) transmission electron microscope (TEM) observation after particle removal, ii) reflectivity simulation. It is found that the image mode of FIB is more effective for particle removal than spot and bar mode.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.4
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• pp.102-108
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• 2010

Projection microstereolithography is a process of fabricating a micro-structure by using dynamic mask such as digital micromirror device(DMD). DMD shapes the beam into cross-sectional image of structure. Photocurable resin is cured by the beam and stacked layer on top of layer. It is difficult to deliver the beam from the DMD to the photocurable resin without any distortions. We assume that the beam exposed to the resin by 1 pixel of DMD has Gaussian distribution, so the shaped beam reflected by the DMD affects its neighboring area. Curing pattern corresponding to a cross-sectional images is predicted by superposition of pixels of Gaussian distribution and it is similar to cured shape.

• Advances in concrete construction
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• v.1 no.2
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• pp.121-136
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• 2013

Tension tests were carried out to investigate the effect of the corrosion pattern on the ductility of tension bars extracted from a 26-year-old corroded reinforced concrete beam. The tensile behavior of corroded bars with different corrosion patterns was examined carefully, as were two non-corroded bars extracted from a 26-year-old control beam. The results show that corrosion leads to an increase in the ratio of the ultimate strength over the yield strength, but reduces the ultimate strain at maximum force of the reinforcement. Both the corrosion pattern and the corrosion intensity play an important role in the ductile properties. The asymmetrical distribution of the corrosion around the surface is a decisive factor, which can influence the ultimate strain at maximum force more seriously.