• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.541-544
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• 2000

본 논문은 부밴드별 반향제거 필터 뱅크를 구현하기 위한 가중 Overlap-add 적응필터를 이용한 단일 채널 음향 반향 제거기를 제안한다. 기준 입력 신호의 고유치 분포율에 의존하여 수렴 특성이 결정되는 NLSM알고리즘을 사용하여 전대역 처리 과정에서 발생하는 수렴성능의 저하를 방지하고, 효율적인 블록별 병렬 처리가 가능한 부밴드 처리기법인 가중 Overlap-add 방식을 적용한 적응 반향제거기의 성능을 고찰한다 또한 본 논문에서는 동시 통화 검출을 위한 전용 필터와 에너지 비교 방법을 동시에 사용하는 새로운 형태의 동시통화 검출 기법을 제안한다.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.11
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• pp.17-23
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• 2010

Titanium alloy is one of the hard processing materials made by the traditional manufacturing method because of the excellent mechanical strength. Ablation of titanium alloy is investigated by using a femtosecond laser which is a regenerative amplified Ti:sapphire laser with 1kHz repetition rate, 184fs pulse duration time and 785nm wavelength. Experiments are carried out under various ablation conditions with different pulse overlap ratios for the rectangular shape and micro hole. Test results show that the ablation characteristic according to pulse overlap ratio of titanium alloy seems to be as non-linear type at the different zone of energy fluence. The optimal condition of rectangular shape processing is obtained at the laser peak power 1.3mW, pulse overlap ratio of 90%, beam gap of $1\;{\mu}m$. The micro hole has a good quality from the pulse overlap ratio of 99% at the same laser peak power. With the optimal processing condition, the fine rectangular shape and micro hole without burr and thermal damage are achieved.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.2
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• pp.118-123
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• 2016

Overlap cutting is a fundamental method of applying abrasive water jet (AWJ) machining to milling to produce a wider surface because the nozzle outlet is approximately 1.0 mm wide. In this study, the effects of overlap cutting on the depth profile and surface roughness are investigated. The overlapping area depends on the amount of step over, which is controlled in the pick-feed direction. If the step over is equal to or larger than the diameter of the nozzle, no overlap cut occurs but large cusps remain between the cut paths. A step over as small as one-thirds of the nozzle diameter may lead to triple-overlap cutting resulting in an extraordinary depth. By using pocket milling experiments with a step over of 0.46 (or 0.47), it is verified that AWJ can produce a milled surface of titanium, one of the hard-to-cut materials, with $76{\mu}m$ Ra.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2688-2690
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• 1999

This paper presents the modeling method of $3{\Phi}$ phase-controlled rectifier considering the overlap interval for the drive of DC motor in the Matlab environment. The model is constructed by the module-based method and therefore it is appropriate in the research of the closed-loop controlled power electronic system in the Matlab/Simulink environment. The model of SCR is used as the element for the power transformation. The simulation results show that the overlap interval from the effect of the input inductance is accurate.

• Journal of the Korean Chemical Society
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• v.22 no.4
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• pp.229-238
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• 1978

Two methods for evaluation of the dipole moment matrix elements are developed, one using the expansion method for spherical harmonics and the other the transformation method of the dipole moment matrix elements into overlap integrals for Mulliken. The numerical values of the dipole moment matrix elements evaluated by two methods are in agreement with each other.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.05a
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• pp.394-397
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• 1999

Impact ionization, which is a kind of a carrier-carrier interaction process occurring in a semiconductor under the influence of a high electric field, is necessary to analyse carrier transport properties. Since the parabolic or nonparabolic E-k relation is different from real band structure in high energy range, exact model of impart ionization have been presented using full band I-k relation and Fermi's golden rule. We have investigated relation of density of states, energy band structure and overlap integral. We make use of empirical pseudopotential method in order to calculate energy band structure of silicon, tetrahedron method in order to calculate density of states. We know density of states very depends on energy band structure and overlap integral depends on the primary electron energy.

• Transactions on Electrical and Electronic Materials
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• v.5 no.3
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• pp.104-108
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• 2004

Problems of overlap errors and side-lobe printing by the design rule reduction in the lithography process using attenuated phase-shifting masks(attPSM) have been serious. Overlap errors and side-lobes can be simultaneously solved by the rule-based correction using scattering bars with the rules extracted from test patterns. Process parameters affecting the attPSM lithography simulation have been determined by the fitting method to the process data. Overlap errors have been solved applying the correction rules to the metal patterns overlapped with contact/via. Moreover, the optimal insertion rule of the scattering bars has made it possible to suppress the side-lobes and to get additional pattern fidelity at the same time.

• Journal of Mechanical Science and Technology
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• v.17 no.6
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• pp.870-878
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• 2003

The scale is removed from the strip by high pressure hydraulic descaling at the FSB (Finishing Scale Breaker). Recently, the spray height of nozzle has a trend to be shorter for the purpose of increasing the impact pressure by the high pressure water jet. Here, the nozzle intervals should be decided after considering the impact pressure and the temperature distribution on the strip. In other words, the minimum of impact pressure at the overlap of spray influences the surface grade of the strip due to scale and the overlap distance of the spray affects the temperature variation in the direction of the width of strip. In the present study, the impact pressure of the high pressure water jet is measured by the hydraulic descaling system and calculated with regard to the lead angle of 15$^{\circ}$ and the offset angle of 15$^{\circ}$, and then the temperature distribution and the temperature variation are calculated at the overlap distances of 0 mm, 10 mm, 20 mm, and 30 mm, respectively. The method of setting nozzle intervals is shown by utilizing these results.

• International Journal of Automotive Technology
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• v.8 no.4
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• pp.395-402
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• 2007

Homogeneous Charge Compression Ignition (HCCI) shows great potential for low $NO_x$ emission but is hampered by the problem of no direct method to control the combustion process. Therefore, HCCI combustion becomes unstable easily, especially at lower and higher engine load. This paper presents a method to achieve diesel-fueled HCCI combustion, which involves directly injecting diesel fuel into the cylinder before the piston arrives at top dead center in the exhaust stroke and adjusting the valve overlap duration to trap more high temperature residual gas in the cylinder. The combustion stability of diesel-fueled HCCI combustion and the effects of engine load, speed, and valve overlap on it are the main points of investigation. The results show that: diesel-fueled HCCI combustion has two-stage heat release rate (low temperature and high temperature heat release) and very low $NO_x$ emission, combustion stability of the HCCI engine is worse at lower load because of misfire and at higher load because of knock, the increase in engine speed aids combustion stability at lower load because the heat loss is reduced, and increasing negative valve overlap can increase in-cylinder temperature which aids combustion stability at lower load but harms it at higher load.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.1
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• pp.90-94
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• 2010

In this paper, we propose a vehicle tracking method that can be applied in the intelligent traffic information system. The proposed method mainly consists of two steps: overlap removal and background updating. In order to remove overlap, we detect the overlap based on the location of the vehicle from successive images. Background updating is to calculate a background using statistical analysis of successive images. We collected a set of test images from the traffic monitoring system and experimented. The experimental results show more than 96% of tracking accuracy.