• Electrical & Electronic Materials
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• v.9 no.6
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• pp.584-592
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• 1996

Coupling optical modulator which on the $LiTaO_3$ substrate is fabricated by using proton exchange method and self-aligned method. Proton exchange of proton diffusion method was applied to pattern a waveguide on $LiTaO_3$ substrate. The annealing at >$400^{\circ}C$ was carded out to control waveguide width and depth. The depths of the two annealed optical waveguides, which were measured by using .alpha.-step, were 1.435 K.angs. and 1.380 K.angs. Using .alpha.-step facility, we examined that the width of waveguides is increased from 5.mu.m to 6.45 .mu.m and 6.3.mu.m due to the annealing effects. The process of proton exchange was done at 150.deg. C for 120 min, >$200^{\circ}C$ for 60 min and annealing process was done at >$400^{\circ}C$ for 90 min, >$400^{\circ}C$ for 60 min. The high speed coupling optical modulator has very good figures of merits; the measured high frequency power were achieved.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.951-954
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• 2003

본 논문에서는 고속. 저전력에 적합한 개방 구조를 갖는 8-비트 500Msmaples/s 2-Step ADC 를 제안하였다. 500Msmaples/s 의 고속 동작을 위해서 기존의 M-DAC을 이용한 폐쇄 구조 대신 개방형 구조를 사용하였다. 이와 더불어 저전력을 구현하기 위해서 analog-latch 를 제안하여 동적 동작을 수행시킴으로써 전력 소모를 줄였으며 , mux 의 구현 시 reset switch를 이용하여 로딩 시간을 개선함으로써 high-speed 에 적합하도록 설계하였다. 제안된 ADC 는 1-poly 6-metal 0.18um CMOS 공정을 이용하였으며 1.8V 전원 전압을 이용하여 250mW 의 전력을 소모하며 500M 샘플링 주파수에서 120MHz 신호 입력 시 7.6 비트의 ENOB를 얻을 수 있었다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.543-549
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• 2000

Results of theoretical investigations of the stability characteristics of an actively controlled externally pressurized air journal bearing are presented. Proportional control and derivative control are used for the control algorithm of active air bearing. The stability characteristics of the actively controlled bearing operating at zero steady-state eccentricity is investigated with the step jump method. The speed at onset of instability is raised for both proportional control and derivative control of bearing. Proportional control increased the stability threshold without affecting the whirl ratio. But for derivative control of bearing, stability threshold increase is accompanied by a parallel reduction of the whirl ratio. Results show active control of bearing can be adopted for the stability improvement of air journal bearing.

• IEMEK Journal of Embedded Systems and Applications
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• v.10 no.1
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• pp.49-55
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• 2015

In this paper, we propose a fast interest point detection method using SURF algorithm. Since the SURF algorithm needs a great computations to detect the interest points and obtain the corresponding descriptors, it is not suitable for real-time based applications. In order to overcome this problem, the interest point detection step is parallelized by OpenMP and SIMD based on analysis of the scale space representation process and localization one in the step. The simulation results demonstrate that processing speed is enhanced about 55% by applying the proposed method.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.8
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• pp.1178-1186
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• 1989

In this paper, a systolic array for polyadic-nonserial DP problems is designed, the performance is analyzed and the efficient operating method is proposed. The algorithm is transformed to remove the broadcasting and global communication paths in the data dependence step by step. The transformed algorithm is mapping to the systolic array using the method proposed by D. I. Moldovan. The designed array is homogenous, had the processing elements of (n+1)/2 and 2n computation time ( n is the size of problem). In case of being many problems to process, the efficiency of array can be upward by inputing the problems successively. The interval between the initiations of two successive proboem instances is [n/2]+1 and the speed-up is about 4. The processor utilizations of each case are calculated.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.3
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• pp.266-272
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• 2012

This paper has aims to share fundamental knowledge for magnetic abrasive polishing and to mainly introduce recent research results. In order to enhance a magnetic flux density for nonferrous materials, advanced magnetic abrasive polishing system which is called 2nd generation system was established by electro-magnet array table, and the effectiveness of the electromagnet array table was evaluated in real polishing experiments. To increase adhesiveness of the abrasives in high speed polishing, a silicone gel agent was proposed and carbon nanotube particles as new magnetic abrasives were applied in the magnetic abrasive polishing. In addition, a strategy for optimal step-over determination by heuristic algorithm was introduced for applying large size workpiece. Curved surfaces having a uniform radius were simulated and tested with installed electro-magnet array table.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.04b
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• pp.381-385
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• 1999

To investigate the influence of the design and operating parameters of the headbox on hydrodynamics, a pilot headbox system and pressure monitoring apparatus were constructed. The pilot headbox system consisted of a circulating water reservoir, centrifugal pump, distributor, step diffusor and slice. The distributor was designed to function as a pressure attenuator. Flow rate to the headbox and MD and CD velocity profiles in the slice zone were monitored using an ultrasonic flowmeter and Pitot tubes, respectively. As the distance from the step diffusor increased, evener CD velocity profile was observed. Wall effect increased with the increase of the velocity. Flow stability in the headbox was evaluated by injecting a dye at the outlet of the distributor. Application of theoretical analysis based on CFD in designing headboxes is briefly discussed.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.565-567
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• 2010

This paper proposes a new Maximum Power Point Tracking (MPPT) control algorithm for PV-Cell (Photo voltaic) based on Incremental Conductance MPPT algorithm. The ICN (Incremental Conductance method) algorithm is widely used due to the high tracking accuracy and adaptability to the rapidly changing isolation condition. In this paper, a modified ICN MPPT algorithm is proposed. This method adjusts automatically the step-size of reference to track the PV-Cell maximum power point, thus it improves the maximum power point tracking speed and accuracy.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.8
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• pp.689-697
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• 1990

This paper proposes ADAPTIVE STOCHASTIC ITERATION ALGORITHM that can be used for the full-duplex digital data transmission over existing twisted-pair cables. The canceller step size changes according to the residual echo level. Thus convergence speed increases by an order of magnitude over the conventional stochastic interation alogorithm. And it can be combined with the sequential type adaptive digital filter that simplifies the conventional echo canceller circuit. Thus it is suitable for LSI implementation. Theoretical analysis on two algorithms is carried out and the algorithm simulation program is developed.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1995.03a
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• pp.34-39
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• 1995

To reduce the shock in shifting the clutches and the brakes in automatic transmission have to be connected smoothly and disconnected rapidly. It is PCSV(Pressure Control Solenoid Valve) that play this role of automatic transmission. In this paper there were two steps in the analysis of the PCSV. The first step was modeling the elctromagnet by the permeance method. The second step was modeling the hydraulic circuit by the pressure differential equation. In addition to this modeling a experiment was performed and the commercial package program was used in order to justify modeling. The result of modeling coincide with the result of experiment and commercial package program. As a result this modeling is usable in analysis of dynamic characteractic of the PCSV.