• 제목/요약/키워드: dual system

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Analysis and Modeling of Dual-Band GSM Networks

  • Lai, Wai-Ru;Lin, Yi-Bing;Herman Chu-Hwa Rao
    • Journal of Communications and Networks
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    • v.1 no.3
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    • pp.158-165
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    • 1999
  • This paper studies interconnection of DCS1800 and GSM900 dual-band networks. Two types of interconnection config-urations for GSM services, non-overlap and overlap, are described. We propose analytic and simulation models to investigate the ben-efit of the overlap configuration. Our results explain how the radio channel capacities, the inter-system handoff failure rate, the origi-nating call traffic ratio and the offered loads affect the system per-formance. This study indicates that with appropriate overlap con-figuration, the GSM dual-band network can significantly improve the quality of cellular service.

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An Optimal Current Distribution Method of Dual-Rotor BLDC Machines

  • Kim, Sung-Jung;Park, Je-Wook;Im, Won-Sang;Jung, Hyun-Woo;Kim, Jang-Mok
    • Journal of Power Electronics
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    • v.13 no.2
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    • pp.250-255
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    • 2013
  • This paper proposes an optimal current distribution method of dual-rotor brushless DC machines (DR-BLDCMs) which have inner and outer surface-mounted permanent-magnet rotors. The DR-BLDCM has high power density and high torque density compare to the conventional single rotor BLDCM. To drive the DR-BLDCM, dual 3-phase PWM inverters are required to excite the currents of a dual stator of the DR-BLDCM and an optimal current distribution algorithm is also needed to enhance the system efficiency. In this paper, the copper loss and the switching loss of a DR-BLDCM drive system are analyzed according to the motor parameters and the switching frequency. Moreover, the optimal current distribution method is proposed to minimize the total electrical loss. The validity of the proposed method was verified through several experiments.

Design of a Dual-Drive Mechanism for Precision Gantry

  • Park, Heung-Keun;Kim, Sung-Soo;Park, Jin-Moo;Daehie Hong;Cho, Tae-Yeon
    • Journal of Mechanical Science and Technology
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    • v.16 no.12
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    • pp.1664-1672
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    • 2002
  • Gantry mechanisms have been widely used for precision manufacturing and material handling in electronics, nuclear, and automotive industries. Dual-drive servo mechanism is a way to increase control bandwidth, in which two primary axes aligned in parallel are synchronously driven by identical servo motors. With this mechanism, a flexible coupling (compliance mechanism) is often introduced in order to avoid the damage by the servo mismatch between the primary drives located at each side of gantry. This paper describes the design guidelines of the dual-drive servo mechanism with focus on its dynamic characteristics and control ramifications. That is, the effect on the system bandwidth which is critical on the system performance, the errors and torques exerted on guide ways in case of servo mismatch, the vibration characteristics concerned with dynamic error and settling time, and the driving force required at each axis for control are thoroughly investigated.

A Full Rate Dual Relay Cooperative Approach for Wireless Systems

  • Hassan, Syed Ali;Li, Geoffrey Ye;Wang, Peter Shu Shaw;Green, Marilynn Wylie
    • Journal of Communications and Networks
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    • v.12 no.5
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    • pp.442-448
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    • 2010
  • Cooperative relaying methods have attracted a lot of interest in the past few years. A conventional cooperative relaying scheme has a source, a destination, and a single relay. This cooperative scheme can support one symbol transmission per time slot, and is caned full rate transmission. However, existing fun rate cooperative relay approaches provide asymmetrical gain for different transmitted symbols. In this paper, we propose a cooperative relaying scheme that is assisted with dual relays and provides full transmission rate with the same macro-diversity to each symbol. We also address equalization for the dual relay transmission system in addition to addressing the issues concerning the improvement of system performance in terms of optimal power allocations.

Fuel Injection System on Combustion and Exhaust Emissions Characteristics in Compression Ignition Engines (압축착화 엔진에서 디젤-가솔린 Dual Fuel이 연소 및 배기 특성에 미치는 영향)

  • Kwon, Seok-Joo;Cha, June-Pyo;Sung, Ki-An;Park, Sung-Wook
    • Journal of the Korean Society of Combustion
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    • v.16 no.1
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    • pp.52-57
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    • 2011
  • The present study describes the characteristics of combustion and exhaust emissions in compression ignition engines using diesel-gasoline dual fuel. For investigating combustion characteristics, diesel fuel was injected directly in a single-cylinder compression ignition engine with a common-rail injection system and gasoline fuel was injected into a premixed chamber installed in an intake port. In order to investigate exhaust emission characteristics, exhaust gas was measured by emission analyzer and smoke meter. The experimental results showed that cases of diesel-gasoline dual fuel combustion exhibited extended ignition delay and reduced peak combustion pressure compared to those of directly injected diesel fuel cases. Furthermore, premixed gasoline-air mixture reduced NOx emissions due to low peak of rate of heat release(ROHR).

Research of Controlled Motion of Dual Fingers with Soft-Tips Grasping (Soft-Tip을 가진 Dual Finger의 파지운동제어에 관한 연구)

  • 박경택;양순용;한현용
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.11a
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    • pp.670-673
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    • 2000
  • This paper attempt analysis and computer simulation of dynamics of a set of dual multi-joint fingers with soft-deformable tips which are grasping. Firstly, a set of differential equation describing dynamics of the fingers and object together with geometric constraint of tight area-contacts is formulated by Euler-Lagrange's formalism. Secondly, problems of controlling both the internal force and the rotation angle of the grasped object under the constraints of area-contacts of tight area-contacts are discussed. The effect of geometric constraints of area-contacts on motion of the overall system is analyzed and a method of computer simulation for overall system of differential-algebraic equations is presented. Finally, simulation results are shown and the effects of geometric constraints of area-contact is discussed.

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Submerged Horizontal and Vertical Membrane Wave Barrier

  • Kee S.T.
    • Journal of Ocean Engineering and Technology
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    • v.19 no.2 s.63
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    • pp.1-11
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    • 2005
  • In the present paper, the hydrodynamic properties of a Rahmen type flexible porous breakwater with dual fixed pontoon system interacting with obliquely or normally incident small amplitude waves are numerically investigated. This system is composed of dual vertical porous membranes hinged at the side edges of dual fixed pontoons, and a submerged horizontal membrane that both ends are hinged at the steel frames mounted pontoons. The dual vertical membranes are extended downward and hinged at bottom steal frame fixed into seabed. The wave blocking and dissipation mechanism and its effects of permeability, Rahmen type membrane and pontoon geometry, pretensions on membranes, relative dimensionless wave number, and incident wave headings are thoroughly examined.

A Dual Vacuum Wafer Prealigner and a Multiple Level Structure (2단 진공 웨이퍼 정렬장치 및 다층 구조 설계)

  • Kim, H.T.;Choi, M.S.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.8 no.3
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    • pp.14-20
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    • 2011
  • This study aims at aligning multiple wafers to reduce wafer handling time in wafer processes. We designed a multilevel structure for a prealigner which can handle multiple wafer simultaneously in a system. The system consists of gripping parts, kinematic parts, vacuum chucks, pneumatic units, hall sensors and a DSP controller. Aligning procedure has two steps: mechanical gripping and notch finding. In the first step, a wafer is aligned in XY directions using 4-point mechanical contact. The rotational error can be found by detecting a signal in a notch using hall sensors. A dual prealigner was designed for 300mm wafers and constructed for a performance test. The accuracy was monitored by checking the movement of a notch in a machine vision. The result shows that the dual prealigner has enough performance as commercial products.

A Study on the 0.5μm Dual Gate High Voltage CMOS Process for Si Liquid Display System (실리콘 액정표시 장치 시스템을 위한 00.5μm 이중 게이트 고전압 CMOS 공정 연구)

  • 송한정
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.15 no.12
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    • pp.1021-1026
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    • 2002
  • As the development of semiconductor process technology continue to advance, ICs continue their trend toward higher performance low power system-on-chip (SOC). These circuits require on board multi power supply. In this paper, a 0.5 ㎛ dual date oxide CMOS Process technology for multi-power application is demonstrated. 5 V and 20 V devices fabricated by proposed process is measured. From 5 V devices using dual gate precess, we got almost the same characteristics as are obtained from standard 5 V devices. And the characteristics of the 20 V device demonstrates that 3 ㎛ devices with minimum gate length are available without reliability degradation. Electrical parameters in minimum 3 ㎛ devices are 520 ㎂/㎛ current density, 120 ㎷ DIBL, 24 V BV for NMOS and ,350 ㎂/㎛ current density, 180 ㎷ DIBL, 26 V BV for PMOS, respectively.

Resouce Allocation for Multiuser OFDM Systems (다중사용자 OFDM 광대역 무선인터넷 시스템의 자원할당 방법)

  • Chung, Yong-Joo;Paik, Chun-Hyun;Kim, Hu-Gon
    • Journal of the Korean Operations Research and Management Science Society
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    • v.32 no.3
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    • pp.33-46
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    • 2007
  • This study deals with the adaptive multiuser OFDM (Orthogonal Frequency Division Multiplexing) system which adjusts the resource allocation according to the environmental changes in such as wireless and quality of service required by users. The resource allocation includes subcarrier assignment to users, modulation method and power used for subcarriers. We first develop a general optimization model which maximizes data throughput while satisfying data rates required by users and total power constraints. Based on the property that this problem has the 0 duality gap, we apply the subgradient dual optimization method which obtains the solution of the dual problem by iteration of simple calculations. Extensive experiments with realistic data have shown that the subgradient dual method is applicable to the real world system, and can be used as a dynamic resource allocation mechanism.