• Title/Summary/Keyword: high speed mode

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The Development of Performance Analysis Code for Pre-Conceptual Design of VTOL UAV (수직이착륙/고속순항 무인기 초기개념설계를 위한 성능예측 프로그램 개발)

  • Jung, Won-Hyung;Lee, Kyung-Tae;Kim, Jung-Yub
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.32 no.5
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    • pp.1-9
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    • 2004
  • The performance analysis code has been developed for vertical take-off and landing(VTOL) UAV which can be utilized as a trade analysis tool in the pre-conceptual design phase. The UAV requires VTOL capability and high speed cruise performance. The main logic of this performance analysis code is to estimate performance parameters of each mission segment by mission fuel weight iteration. The reliability of this performance analysis code is discussed by comparing the data of existing dual flight mode VTOL UAVs such as Boeing CRW and Bell Tilt Rotor.

Performance Analysis on Clock Sychronization of CCK Modulation Scheme in Wireless LAN System (무선 LAN 시스템에서 CCK 변조방식의 클럭 동기 성능 분석)

  • 박정수;강희곡;조성언;조성준
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2004.05b
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    • pp.583-586
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    • 2004
  • In this paper, we have analyzed the performance of synchronization of CCK(Complementary Code Keying) modulation scheme used for IEEE 802.11g wireless LAM system supporting 54 Mbps of high speed data rate over 2.4 GHz. At receiver, the clock frequency offset is caused by noise or fading. This frequency error occurs the offset of clock timing and causes ISI. Therefore the tracking is required to reduce the clock timing offset. The DLL(Delay Lock Loop), asychronization mode, performing tacking the clock is used for the simulation. The simulation result shows jitter variance and BER performance in the AWGN and multipath fading channel environment.

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Three Phase Current Reconstruction Method of Three Shunt Sensing 3-Phase Inverter by Predictive Current Technique (예측 전류 기법을 적용한 3-션트 전류검출 3상 인버터의 전류 복원 방법)

  • Choo, Kyoung-Min;Hong, Sung-Woo;Jang, Young-Hee;Won, Il-Kuen;Kim, Do-Yun;Wo, Chung-Yuen
    • The Transactions of the Korean Institute of Power Electronics
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    • v.22 no.2
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    • pp.175-180
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    • 2017
  • The measurement of three-phase current is important to control the instantaneous torque of a interior permanent magnet synchronous motor(IPMSM) using a three-phase inverter. Therefore, shunt resistors are used in low-cost motor-driving systems to measure three-phase current instead of additional current sensors that are too expensive for these systems. However, in certain regions of a space vector plane, shunt resistors cannot reconstruct three-phase current in high-speed driving mode. In this paper, predictive current control is used to compensate for the three-phase current in those regions, which results in a reduction of current ripple in a three-shunt sensing inverter(TSSI) and torque ripple in IPMSM.

Development of Transmission Simulator for High-Speed Tracked Vehicles (고속 무한궤도 차량용 변속기 시뮬레이터 개발)

  • Jung, Gyuhong
    • Journal of Drive and Control
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    • v.14 no.4
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    • pp.29-36
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    • 2017
  • Electronic control technologies that have long been developed for passenger cars spread to construction equipment and agricultural vehicles because of its outstanding performance achieved by embedded software. Especially, system program of transmission control unit (TCU) plays a crucial role for the superb shift quality, driving performance and fuel efficiency, etc. Since the control algorithm is embedded in software that is rarely analyzed, development of such a TCU cannot be conducted by conventional reverse engineering. Transmission simulator is a kind of electronic device that simulates the electric signals including driver operation command and output of various sensors installed in transmission. Standalone TCU can be run in normal operation mode with the signals provided by transmission simulator. In this research, transmission simulator for the tracked vehicle TCU is developed for the analysis of shift control algorithm from the experiments with standalone TCU. It was confirmed that shift experimental data for the simulator setup conditions can be used for the analysis of control algorithms on proportional solenoid valves and shift map.

Environmental Noise Prediction using Scale Model: A Measurement Methodology

  • Kim, Tae-Min;Han, Jae-Hyun;Kim, Jeung-Tae
    • International Journal of Railway
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    • v.4 no.2
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    • pp.42-49
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    • 2011
  • Today, rolling stock has become a fast and convenient mode of transportation and has witnessed increased demand. But the speed improvement has resulted in increased aerodynamic noise and therefore residential districts near the railroad tracks are exposed to ever increasing noise level. A study on methodologies for measuring and appraising rolling stock's environmental noise has therefore become an important area of endeavor. In the case of the environmental noise, there are no changes in tone so prediction can be made by reducing areas around the railway. The present study explores estimation of the noise around the railway using scale model, and the source of the noise has been investigated as well. The scale model of rolling stock will have to be able to measure high frequency noise and it is required to be generated in a short amount of time. Since popping a balloon or firing a gun fits this requirement the present study analyzed the characteristics of these two different noise sources. Measurement was made in a large vacant lot and the reflection due to the ground was also examined. The method proposed here can be used in the future for predicting the environmental noise of railway vehicles.

A study on railway logistic transportation efficiency through constructing roundabout route of the Kyung-Bu railroad (경부선 우회선로 구축을 통한 철도화물운송 효율화 방안 연구)

  • Kim, Jong-Tae;Choo, Jun-Sup;Moon, Dae-Seop;Yoo, Jae- Kyun;Lee, Jun;Oh, Seok-Moon
    • Proceedings of the KSR Conference
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    • 2008.11b
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    • pp.657-665
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    • 2008
  • The main transportation mode of long distance inter-city passenger trips is high-speed rail and the modal share of transportation has been changed profoundly since the KTX service has been started in the Kyung-Bu railroad transportation corridor in the day of 1 April, 2004. After an opening of KTX service in the second stage Kyung-Bu and Ho-Nam railroad transportation corridors, a capacity of incumbent railroads will be increased and operational environments of freight train will be improved. The purpose of this paper is to examine the impact of KTX service operation on the national logistics thoroughly. This paper establishes a deceptive scheme in the national railroad logistic transportation and a route operational strategy between the main origins and destinations efficiently considering the changes of the current freight transportation system in the future. We expect to achieve efficiency of logistic transportation in this paper through alternative routes for example Ho-Nam, Chang-Hang, Seo-Hae line.

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Economical Gas Chamber for In-situ Gas Measurement and Analysis of Gas Response Characteristics according to Sensor Voltage (인시투 가스 측정이 가능한 경제적 가스 챔버 구현 및 센서 전압에 따른 가스 응답 특성 분석)

  • Choi, Yun-Suk;Lee, In Hwan
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.18 no.5
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    • pp.1-8
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    • 2019
  • Breath analysis using a portable device is better than the classical breath analysis system in terms of installation and operation. There is an increasing need to develop cost-effective equipment for testing gas sensors from the viewpoint of functionalities that can be applied applicable to portable devices. In the present study, an economical gas chamber for in-situ gas measurement is implemented with a single gas chamber without using expensive gas storage and control equipment; the gas response characteristics are analyzed using the above-described chamber. The main features of the implemented gas chamber are simple injection procedure, improved gas diffusion, easy measurement and cleaning, support for low-power mode measurement function for portable devices, and open source platform. Moreover, an analysis of gas response characteristics based on changes in sensor voltage show that the sensitivity and 90% response time are affected by the sensor voltage. Furthermore, the sensitivity graph has an inflection point in a specific range. The gas sensor applied in this study showed fast response speed and high sensitivity for sensor voltages of 3.0-3.5 V, regardless of the concentration of acetone gas, the target gas used in this study.

Evolutionary-base finite element model updating and damage detection using modal testing results

  • Vahidi, Mehdi;Vahdani, Shahram;Rahimian, Mohammad;Jamshidi, Nima;Kanee, Alireza Taghavee
    • Structural Engineering and Mechanics
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    • v.70 no.3
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    • pp.339-350
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    • 2019
  • This research focuses on finite element model updating and damage assessment of structures at element level based on global nondestructive test results. For this purpose, an optimization system is generated to minimize the structural dynamic parameters discrepancies between numerical and experimental models. Objective functions are selected based on the square of Euclidean norm error of vibration frequencies and modal assurance criterion of mode shapes. In order to update the finite element model and detect local damages within the structural members, modern optimization techniques is implemented according to the evolutionary algorithms to meet the global optimized solution. Using a simulated numerical example, application of genetic algorithm (GA), particle swarm (PSO) and artificial bee colony (ABC) algorithms are investigated in FE model updating and damage detection problems to consider their accuracy and convergence characteristics. Then, a hybrid multi stage optimization method is presented merging advantages of PSO and ABC methods in finding damage location and extent. The efficiency of the methods have been examined using two simulated numerical examples, a laboratory dynamic test and a high-rise building field ambient vibration test results. The implemented evolutionary updating methods show successful results in accuracy and speed considering the incomplete and noisy experimental measured data.

Experimental investigations on the resistance performance of a high-speed partial air cushion supported catamaran

  • Yang, Jinglei;Lin, Zhuang;Li, Ping;Guo, Zhiqun;Sun, Hanbing;Yang, Dongmei
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.12 no.1
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    • pp.38-47
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    • 2020
  • The partial air cushion supported catamaran (PACSCAT) is a novel Surface Effect Ship (SES) and possesses distinctive resistance performance due to the presence of planing bottom. In this paper, the design of PACSCAT and air cushion system are described in detail. Model tests were carried out for Froude numbers ranging from 0.1 to 1.11, the focus is on the influence of air cushion system on resistance characteristics. Drag-reducing effect of air cushion system was proved by means of contrast tests in cuhionborne and non-cushionborne mode. Wave-making characteristics reflect that the PACSCAT would eventually enter planing regime, in which the air could just escape under the seals and the hull body could operate in a steady state. To acquire different air cushion pressure, air flow rate and leakage height were adjusted during tests. Experimental results show that the resistance performance in planing regime would decrease evidently as the increased air flow rate, however, the scheme with medium leakage height presents the best resistance performance in the hump region.

Three Phase Drive Transfer Algorithm for Fault Tolerance Control of Six-Phase PMSM (6상 영구자석 동기전동기의 고장대응운전을 위한 3상 구동시스템 전환 알고리즘)

  • Kim, Seong-Hoon;Jang, Won-Jin;Cho, Kwan-Yuhl;Kim, Hag-Wone
    • The Transactions of the Korean Institute of Power Electronics
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    • v.26 no.4
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    • pp.256-262
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    • 2021
  • Six-phase motors can be used in industrial applications, such as an electric vehicle, due to their high reliability and low current magnitude per phase. An asymmetrical PMSM with two sets of three-phase windings is a commonly used structure for six-phase motors, with each winding set demonstrating a phase difference of 30°. Although the asymmetrical PMSM presents low torque ripples, its dynamic torque response deteriorates due to coupled components in the two three-phase windings. The decoupled VSD control is applied to eliminate the coupling effect. Load ratio control of two inverters for the six-phase PMSM is proposed in this study. DQ currents are controlled on the basis of two synchronous reference frames, and the six-phase drive system can be changed to a three-phase drive system when one inverter presents fault conditions. The operation and effectiveness of the proposed algorithm is verified through simulation and experiments. The six-phase drive system is transferred to a three-phase drive system by changing the current reference of the second DQ reference frame. Moreover, control of both torque and speed exhibits satisfactory performance before and after the mode change.