• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.383-384
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• 2015

DC system is still unexploited in public distribution systems. As the weight of cost efficiency and reliability requirements of distribution networks are expected to increase in the future, with the utilization of distributed generation, there will be demand for novel distribution techniques. The utilization of the Low Voltage DC (LVDC) distribution system opens new possibilities for network development. This paper presents analysis of steady state and transient state according to the number of pole in LVDC distribution system.

• Journal of Communications and Networks
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• 제4권4호
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• pp.344-350
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• 2002

This work summarizes the current state of the art in software radio for 4G systems. Specifically, this work demonstrates that classic radio structures, e.g., heterodyne reception, homodyne reception, and their improved implementations, are inadequate selections for multi-mode reception. This opens the door to software defined radio, a novel reception architecture which promises ease in multi-band, multi-protocol design. The work presents the many advantages of such an architecture, including flexibility, reduced cost via component reduction, and improved reliability via, e.g., the elimination of environmental instability. The work also explains the limitations that currently curtail the widespread use of SDR, including issues surrounding A/D converters, management of software and power, and clock generation. This provides direction for future research to enable the broad applicability of SDR in 4G cellular and beyond.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권11호
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• pp.541-547
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• 2003

Speed and torque controls of permanent magnet synchronous motors are usually attained by the application of position and speed sensors. However, speed and position sensors require the additional mounting space, reduce the reliability in harsh environments and increase the cost of a motor. Therefore, many studies have been peformed for the elimination of speed and position sensors. This paper investigates a novel speed sensorless control of a permanent magnet synchronous motor. The proposed control strategy is based on the MRAS(Model Reference Adaptive System) using the state observer model with the current error feedback and the magnet flux model as two models for the back-emf estimation. The proposed algorithm is verified through the simulation and experiment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1042-1045
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• 2000

Speed control without speed sensor is expected strongly to progress reliability, simplicity and cost performance of I.M and to expand its application part. This paper investigates a novel speed estimation method of I.M considering the secondary resistance identification based on the transientless torque control technique. Especially, this paper aimed at the identification of the secondary resistance simultaneously with speed estimation. For this, the secondary flux with some frequency is controlled independently on torque. The proposed speed estimation method is derived from a motor circuit equation theoretically and also it can be conducted easily by detecting primary motor currents and primary voltage commands at every sampling time. Some numerical simulations with the assumption of using a pulse width modulation(PWM) voltage source inverter and experimental results are performed to verify the proposed method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.92-94
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• 2005

Speed and torque controls of permanent magnet synchronous motors are usually attained by the application of position and speed sensors. However, speed and position sensors require the additional mounting space, reduce the reliability in harsh environments and increase the cost of a motor. Therefore, many studios have been performed for the elimination of speed and position sensors. This paper investigates a novel speed sensorless control of a permanent magnet synchronous motor. The proposed control strategy compensates a speed error through the difference between the calculated and measured reactive power. The proposed algorithm is verified through the simulation and experimentation.

• International Journal of Computer Science & Network Security
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• 제23권2호
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• pp.140-146
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• 2023

With the rapid growth of new users and massive need for very high data rate in 5G communications system, different technologies have been developed and applied to enhance communication efficiency. One of those technologies is the MISO, MISO and MIMO which transmits and receives information with more reliability by using multiple antennas on transmitter or/and receiver side. This paper presents the latest trends in 5G telecommunications system based on software defined radio, A novel low-cost SIMO, MISO and MIMO using flexibility between USRP and Simulink is implemented tested and validated.

• 한국정밀공학회지
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• 제20권5호
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• pp.218-224
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• 2003

This paper describes a novel MEMS integration technique on a CMOS chip. MEMS integration on CMOS circuit has many advantages in view of manufacturing cost and reliability. The surface topography of a CMOS chip from a commercial foundry has 0.9 ${\mu}{\textrm}{m}$ bumps due to the conformal coating on aluminum interconnect patterns, which are used for addressing each MEMS element individually. Therefore, it is necessary to achieve a flat mirror-like CMOS chip fer the microelectromechanical system (MEMS) such as micro mirror array. Such CMOS chip needs an additional thickness of the dielectric passivation layer to ease the subsequent planarization process. To overcome a temperature limit from the aluminum thermal degradation, this study uses RF sputtering of silicon nitride at low temperature and then polishes the CMOS chip together with the surrounding dummy pieces to define a polishing plane. Planarization reduces 0.9 ${\mu}{\textrm}{m}$ of the bumps to less than 25 nm.

• 전력전자학회논문지
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• 제8권2호
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• pp.107-115
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• 2003

PMSM은 높은 토크 특성과 우수한 전력 밀도, 논은 효율 때문에 산업용 빛 가정용 기기로 널리 사용되고 있다. PMSM의 우수한 제어 수행을 위해서는 회전자 위치의 정확한 정보가 필요하다. 그러나 위치 센서의 가격이 비싸고, 열악한 환경에서 신뢰도가 떨어지기 때문에 최근에는 센서리스 알고리즘에 대한 연구가 많이 진행되고 있다. 본 논문에서는 회전자 위치의 추정을 위해 쇄교 자속의 도함수를 이용한다. 수치적 미분을 행하지 않고 전압 방정식과 측정된 상전류를 이용한 수식적 미분을 통해 쇄교 자속을 구하는 a-$\beta$ 변환과 수식적 미분을 이용한 새로운 센서리스 알고리즘을 제안한다. 제안된 센서리스 속도 제어 알고리즘이 실험을 통해 증명된다.

• Smart Structures and Systems
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• 제9권1호
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• pp.1-20
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• 2012

In bridge engineering, maintenance strategies and thus budgetary demands are highly influenced by construction type and quality of design. Nowadays bridge owners and planners tend to include life-cycle cost analyses in their decision processes regarding the overall design trying to optimize structural reliability and durability within financial constraints. Smart permanent and short term monitoring can reduce the associated risk of new design concepts by observing the performance of structural components during prescribed time periods. The objectives of this paper are the discussion and analysis of influence line or influence field approaches in terms of (a) an efficient incorporation of monitoring information in the structural performance assessment, (b) an efficient characterization of performance indicators for the assessment of structures, (c) the ability of optimizing the positions of sensors of a monitoring system, and (d) the ability of checking the robustness of the monitoring systems applied to a structure. The proposed influence line- model correction approach has been applied to an integrative monitoring system that has been installed for the performance assessment of an existing three-span jointless bridge.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.530-535
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• 2002

Pneumatic control system has been applied to build many industrial automation systems. But most of them are sequence control type because of their low costs, safety, reliability, etc. Pneumatic servo system is rarely applied to real industrial fields because accurate position control is very difficult due to its nonlinearity and compressibility of air. In pneumatic servo control system, a pneumatic servo valve can be applied, But it is very expensive and has no advantage of low cost compared with a common pneumatic system. This paper is concerned with the accurate position control of a rodless pneumatic cylinder using on/off solenoid valve. A novel Intelligent Modified Pulse Width Modulation(MPWM) is newly proposed. The control performance of this pneumatic cylinder depends on the external loads. To overcome this problem, switching of control parameter using artificial neural network is newly proposed, which estimates external loads on rodless pneumatic cylinder using this training neural network. As an underlying controller, a state feedback controller using position, velocity and acceleration is applied in the switching control the system. The effectiveness of the proposed control algorithms are demonstrated through experiments nth various loads.