• Title/Summary/Keyword: dual method

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Design of A Dual Band Branch Line Coupler Using a CRLH Transmission Line Structure (CRLH 전송선로 구조를 이용한 이중대역 브랜치 라인 커플러 설계)

  • Park, Min-Woo;Koo, Ja-Kyung;Lim, Jong-Sik;Jeong, Yong-Chae;Ahn, Dal
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.12
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    • pp.2462-2467
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    • 2009
  • This paper proposes a dual band branch line coupler (BLC) using a composite right/left handed (CRLH) transmission line. The existing dual band BLCs with open stubs require hundreds of line impedance for the open stub as the frequency bands approach to each other, so it has been almost impossible to realize them. However in the proposed BLC, a CRLH transmission line replaces the open stub with an extremely high line impedance so that the BLC circuit may be realized even two frequencies are close to each other. As an example, a dual band BLC operating at 1800MHz and 2300MHz (the frequency ratio is 1:1.28) is designed and measured. Open stubs with $560\Omega$ line impedance are replaced by CRLH transmission lines for realizing the dual band BLC. The measured performances prove that the dual band operation is well acceptable and the proposed design method is successful even the ratio between two frequencies is not around two nor more.

Study on Vertical Axis Water Turbine with Movable Dual Blades (가변형 이중 날개를 갖는 수직축 수류터빈에 대한 연구)

  • Kim, Do-Hyung;Ahn, Byoung-Kwon
    • Journal of Ocean Engineering and Technology
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    • v.30 no.2
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    • pp.125-133
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    • 2016
  • In this paper, we propose a vertical axis water turbine with dual blades. A parametric study was conducted using numerical analyses. First, a two-dimensional finite-volume analysis with a commercial code was used to find the pitch angle of the main blade under different tip speed ratio conditions. Second, we developed a potential-based panel method to find the best configuration of the inner blades. Experimental tests were conducted at the circulating water channel of Chungnam National University. Various configurations of the dual blades were considered, and their performances were comparatively investigated. The results showed that the turbine with movable dual blades produces a constant torque and tip speed ratio at various flow rates.

Performance Enhancement of Optical Disk Drive Servo System using Dual modified Disturbance Observer (광디스크 드라이브 서보 시스템을 위한 수정된 외란관측기)

  • Kim, Moo-Sub;Chung, Chung-Choo
    • Proceedings of the KIEE Conference
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    • 2004.11c
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    • pp.738-740
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    • 2004
  • The disturbance observer is effective in enhancing the performance of position control in high speed optical disk drive systems(ODDS). It is known that error based modified disturbance observer (EM-DOB) is more effective structure than general DOB. It has a simple structure and realization, but it loses robustness. We propose a dual modified disturbance observer(Dual mDOB). It consists of internal loop EM-DOB and external loop DOB. Those loops are designed for different objects. We see that the dual mDOB is an effective method for tracking performance.

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An Experimental Study on Combustion and Exhaust Emissions Characteristics in RCCI (Reactivity Controlled Compression Ignition) of Dual-Fuel (Diesel+Gasoline) (2중연료(디젤+가솔린)의 RCCI 연소 및 배기 특성에 관한 실험적 연구)

  • Sung, K.A.
    • Journal of ILASS-Korea
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    • v.16 no.1
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    • pp.51-57
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    • 2011
  • An experimental study was performed to explore characteristics of combustion and exhaust emissions in the compression ignition engine of RCCI (reactivity controlled compression ignition) using diesel-gasoline dual fuel. A dual-fuel reactivity controlled compression ignition concepts is demonstrated as a promising method to achieve high thermal efficiency and low emissions. For investigating combustion characteristics, engine experiments were performed in a light-duty diesel engine over a range of SOIs (start of injection) and gasoline percents. The experimental results showed that cases of diesel-gasoline dual fuel combustion is capable of operating over a middle range of engine loads with lower levels of NOx and soot, acceptable pressure rise rate, low ISFC (indicated specific fuel consumption), and high indicated thermal efficiency.

Background Noise Reduction Algorithm Based on Frequency Domain Adaptive Filter and MMSE-LSA in Dual-microphone situation (Dual-microphone 환경에서 주파수 영역 적응 필터와 MMSE-LSA기반 배경 잡음 알고리즘)

  • Lee, Keunsang;Park, Youngchul
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.6 no.1
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    • pp.23-28
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    • 2013
  • In this paper, background noise reduction method using dual microphone is proposed in mobile environment. Each Signal, reference and primary, would be replaced by microphone input signals, which were measured by reference and primary microphones, and then, noise reduction was performed using FDAF. After then, residual and background noise would be estimated and reduced by MMSE-LSA. For consistent noise reduction performance, result of VAD that could be caculated by PLD between two microphones was used.

Resonance Suppression using Sensorless Control of Dual SPMSMs Fed by Single Inverter

  • Eom, Jae-Boo;Choi, Jong-Woo
    • Journal of Electrical Engineering and Technology
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    • v.13 no.6
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    • pp.2376-2384
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    • 2018
  • To reduce the size and cost of motor driving systems, several methods for driving multiple parallel-connected motors with a single inverter have been proposed. However, dual PMSMs driven by a single inverter, unlike induction motors, have a problem with instability due to system resonance caused by disturbances such as load imbalance and tolerances between two motors. To drive dual SPMSMs fed by a single inverter, this paper proposes an active damping algorithm to effectively suppress resonance by using one-sided sensorless speed control and position difference estimation. By deriving rotor position difference from d-q current differences between two motors, the proposed method is affected less by position difference estimation errors and is simpler than dual sensorless position estimation.

Performance Analysis of GPS Anti-Jamming Method Using Dual-Polarized Antenna Array in the Presence of Steering Vector Errors

  • Park, Kwansik;Seo, Jiwon
    • Journal of Positioning, Navigation, and Timing
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    • v.9 no.2
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    • pp.59-63
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    • 2020
  • The antenna arrays are known to be effective for GPS anti-jamming and the performance can be improved further if a dual-polarized antenna array is used. However, when the Minimum Variance Distortionless Response (MVDR) beamformer is used as a signal processing algorithm for the dual-polarized antenna array, the anti-jamming performance can degrade in the presence of errors in the steering vector that is a key factor of the MVDR beamformer. Therefore, in this paper, the effect of the steering vector error on the anti-jamming performance of the dual-polarized antenna array is analyzed by simulations and the result is compared to that of the single-polarized antenna array.

Dual-band L-section Impedance Transformer (이중 대역 L형 임피던스 변환기)

  • Park, Myun-Joo
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.9 no.5
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    • pp.67-71
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    • 2010
  • This paper proposes new dual-band impedance transformers based on the L-section circuit topology. The proposed circuits consist of a transmission line section with a stub line either at the source or at the load end. The dual-band operating conditions are analyzed in detail and simple design equations are derived in terms of the line lengths and impedances for the different circuit topologies and load conditions. The dual-band operation is confirmed through the design, fabrication and measurement in microstrip circuits based on the proposed method.

Control Algorithm of Thyristor Dual Converter Power System for Railway Power Substations (철도 변전설비를 위한 싸이리스터 이중 컨버터 전력 시스템의 제어 기법)

  • Han, Sung-Woo;Lee, Chang-Hee;Kim, Young-Woo;Moon, Dong-Ok
    • The Transactions of the Korean Institute of Power Electronics
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    • v.20 no.6
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    • pp.573-579
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    • 2015
  • A control algorithm of thyristor dual converter power system is proposed in this study for a railway power substation. The thyristor dual converter can use regenerative power without an additional system using control algorithm. An autonomous voltage and mode change method is also proposed to provide uninterrupted power to the railway. A 10 kW reduced model of the thyristor dual converter power system is built and tested to verify the validity of the proposed control algorithm.

Grasp Stability Analysis in Dual-Space and Optimal Grasp Planning for Two-Fingered Robots in 2-D (듀얼 공간을 이용한 이차원 두 손가락 로봇의 파지 안정성 분석 및 최적 파지 계획)

  • Kook, Myung-Ho;Jang, Myeong-Eon;Lee, Ji-Hong
    • Journal of Institute of Control, Robotics and Systems
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    • v.12 no.11
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    • pp.1102-1110
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    • 2006
  • This paper addresses the problem of computing grasp stability of the object for two-fingered robots in two dimensions. The concepts of force-closure and dual space are introduced and discussed in novel point of view, and we transform friction cones in a robot work space to line segments in a dual space. We newly define a grasp stability index by calculating intersection condition between line segments in dual space. Moreover, we propose a method to find the optimal grasp points of the given object by comparing the defined grasp stability index. Its validity and effectiveness are investigated and verified by simulations for quadrangle object and elliptic objects.