• 한국전자파학회논문지
• /
• 제15권11호
• /
• pp.1075-1081
• /
• 2004

본 논문에서는 PHEMT의 소 신호 산란계수를 이용하여 일본에서 사용하는 X-band 대역의 차량 속도 사전 제한 경보기용(Radar Detector) 전압제어 발진기를 설계 제작하였다. 전압 제어 발진기를 구현하기 위해서 넓은 동조 범위와 직렬저항이 0옴인 바렉터 다이오드를 사용하였고, 트랜지스터의 작동전압과 공진 주파수를 결정하는 마이크로 스트립 선로와 바렉터 소자와의 반사계수를 조정하여 위상잡음은 10kHz 오프셋에서 -85 dBc/Hz, 기본 주파수 신호 출력 크기는 +4.5 dBm, 제2고조파 억제는 -25.6 dEc를 얻었다. 본 논문에서 제작한 샘플이 감도에서 기존 제품들보다 우수한 특성이 나오는 것을 확인할 수 있었다.

• 풍력에너지저널
• /
• 제2권1호
• /
• pp.90-96
• /
• 2011

The purpose of this paper is to describe the control system for optimal performance of 2MW gearless PMSG wind turbine system, and to afford some techniques of the algorithm selection and design optimization of the wind turbine control system through analysis of load calculation and control characteristic. Wind turbine control system is composed of the main control system and remote control and monitoring system. The main control system is industrial PC based controller, and the remote control and monitoring system is a server based computer system. The main control system has a supervisory control of the wind turbine with operation procedures and power-speed control through the torque control by pitch angle. There are some applications to optimize the wind turbine system at the starting mode with increasing of rotor speed, and cut-in operating mode to prevent trundling cut-in and cut-out, a gain scheduling of pitch PID controller, torque scheduling and limitation of generation power by temperature limitation or remote command by remote control and monitoring system. Also, the server operation program of the remote control and monitoring system and the design of graphical display are described in this paper.

• 한국지능시스템학회논문지
• /
• 제14권7호
• /
• pp.907-913
• /
• 2004

일반적인 이동 로봇의 주된 관심은 경로 생성과 생성된 경로 추종에 있다. 그러나 일부 고속의 이동성이 필요로 하는 로봇의 경우 동역학적 제한 조건이 존재하며, 이러한 제한 조건 내에서 원하는 움직임에 대한 제어가 요구된다. 된 논문에서 환경 지도를 가지고 있지 않은 상태, 즉 미지의 환경에서 이동 로봇의 경로 추종에 있어서 빠른 이동시에 발생할 수 있는 이동 로봇의 미끄러짐이나 전복 현상을 막기 위해 이동 로봇의 동역학적 제한 조건을 퍼지 논리를 이용하여 기준 속도를 변화시켜 안전하고 빠는 경로 추종 성능을 얻고자 하였다. 특히, 라인 추종 이동 로봇을 모델링하여 실시간으로 변화하는 목표점에 대한 추종 제어기를 설계하고 퍼지 최적 속도 제한 제어기를 통해 연속적으로 변화하는 라인에 대해서 지능적으로 로봇의 속도를 제한하여 안정적인 추종 성능을 발휘함을 확인하였다.

• Journal of Information Processing Systems
• /
• 제16권5호
• /
• pp.1064-1073
• /
• 2020

The general situation of system composition and safety management of high-speed railway terminal is investigated and a comprehensive evaluation index system of operational security is established on the basis of railway laws and regulations and previous research results to evaluate the operational security management of the high-speed railway terminal objectively and scientifically. Index weight is determined by introducing interval eigenvalue method (IEM), which aims to reduce the dependence of judgment matrix on consistency test and improve judgment accuracy. Operational security status of a high-speed railway terminal in northwest China is analyzed using the traditional model of fuzzy comprehensive evaluation, and a general technique idea and references for the operational security evaluation of the high-speed railway terminal are provided. IEM is introduced to determine the weight of each index, overcomes shortcomings of traditional analytic hierarchy process (AHP) method, and improves the accuracy and scientificity of the comprehensive evaluation. Risk factors, such as terrorist attacks, bad weather, and building fires, are intentionally avoided in the selection of evaluation indicators due to the complexity of risk factors in the operation of high-speed railway passenger stations and limitation of the length of the paper. However, such risk factors should be considered in the follow-up studies.

• 대한전기학회논문지
• /
• 제35권12호
• /
• pp.541-554
• /
• 1986

This paper presents the results of driving performance analysis of permanent magnet synchronous motor using a microprocessor based control system. The system consists of three phase power transistor inverters, three phase controlled rectifier, three central processing units, and sensors. The three CPUs are, respectively, used to generate PWM control signals for the inverter generating three phase sine wave, to generate the gate control signals for firing the converter, and to supervise other two CPUs. The supervisor is used to compute PI control algtorithm to three phase reference sine wave for the inverter. It is also used to maintain a constant voltage frequency ratio for the converter operating as a constant torque controller. The inverter CPU retrieves precomputed PWM patterns from look up tables because of computation speed limitations found in almost available microprocessors. The converter CPU also retrieves precomputed gate control patterns from another look-up tables. For protecting the control ststem from any damage by extraordinary over currents, the supervisor receives the data from current sensor, CT, and break down the CB to isolate the circuits from source. A resolver has a good performance characteristics of overall speed range, especially on low speed range. Therefor the speed control accuracy is impoved. The microprocessor based PM synchronous motor control system, thus, has many advantages such as constant torque characteristics, improvement of wave, limitation on extraordinary over currents, improvement of speed control accuracy, and fast response speed control using multi-CPU and look-up tables.

• 대한조선학회논문집
• /
• 제56권5호
• /
• pp.396-409
• /
• 2019

In this paper, a comparative study on the radiation techniques for the motion analysis of the three dimensional floating structure with the forward speed was carried out. The Sommerfeld radiation condition, the damping technique, and the point shift technique were used for the comparative study. Radiated wave patterns and hydrodynamic coefficients of the heave motion of floating structure with the forward speed were compared and analyzed. The characteristics and limitations of each radiation technique were analyzed through the calculation results. To overcome the limitations of conventional radiation techniques, the hybrid radiation technique combining the Sommerfeld radiation condition with the damping technique was proposed. It is confirmed that the proposed method, the Hybrid radiation technique, improves the limitation of the speed range and the dissipation of the wave of the conventional radiation technique. The motion analysis code of the three dimensional floating structure with the forward speed based on the Rankine source method with hybrid radiation technique was developed. In order to validate the developed code, hydrodynamic analyses were carried and compared with published experiments.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
• /
• pp.361-362
• /
• 2007

This paper presents the Traffic information system that based on an embedded WinCE board which has GPS and HSDPA. This system is able to overcome the limit of area using the Internet service which other systems can't provide. When the embedded board receives data about the geometric and vehicle speed information, it transmits to the server via HSDPA/the Internet. The server receives and processes it for the path services. And also we present the path guidance algorithm which is based on the speed information. These algorithm responses to the dynamical traffic condition through updating traffic information. Especially, we suggest a Traffic Status Variable in each branch which represents each road's traffic status. This Traffic Status Variable contains speed, road grade; we separate the road three groups as speed limitation; and past speed data - for example, week day rush hour of each road. In addition, the data of cross about left-turn or right-turn can update. Those elements is consisted Traffic Status Variable.

• 한국정보시스템학회지:정보시스템연구
• /
• 제7권1호
• /
• pp.55-76
• /
• 1998

Various trials to overcome the limitation of current accounting which fails in synchronizing business activities and their information have failed to make satisfactory result merely showing a little saving of processing time. This is because such trials have been done within the boundary of double-entry bookkeeping system. Without consolidating business activities and their information, reformation efforts such as BPR(business process re-engineering), ABC(activity-based costing), CALS(commerce at light speed) etc to fit the business organization to the changing business environment could not be achieved. Overcoming the limitation of accounting takes precedence of any other attempt to construct the management information systems. Activity Information Accounting System(AIAS) proposes the way of overcoming the limitation of current accounting by using the new accounting methodology and unique solution to real time accounting information. AIAS produces accounting and management information directly of activity information without bookkeeping process of activity information. AIAS adopts method of transforming the details of corporation activities directly into accounting information rather than method of double-entry bookkeeping system. The purpose of this paper is to prove AIAS to be very flexible system by using flexibility concepts. Flexibilities are defined as three aspects, namely ① timeliness (rapid accounting information generations and presentations) ② easy systems modificabilities according to environment changes ③ adaptabilities to all industries.

• 전력전자학회논문지
• /
• 제20권2호
• /
• pp.193-199
• /
• 2015

This paper proposes a regeneration braking algorithm for Brushless DC (BLDC) motor system. The unipolar switching method has a limitation about the regeneration braking when the BLDC motor is operated in the low speed region. The proposed algorithm alternatively utilizes the unipolar and bipolar switching method to implement the regeneration braking for overall speed range. The bipolar switching method is used when the BLDC motor is operated in the low speed region. The switching transition point is determined by analyzing the unipolar and bipolar switching during the regeneration braking. The effectiveness of proposed algorithm is verified by using the experimental results.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2011년도 전력전자학술대회
• /
• pp.103-104
• /
• 2011

This paper suggests a new starting and stopping method appropriate for the sensorless PMSM drive with air bearings. The proposed method based on the sensorless control algorithm of PMSM uses additional d-axis current control to cope with the limitation of the adopted back-emf based sensorless algorithm in the low speed region. The experimental results show that the proposed method drives appropriately the PMSM with air bearings.