• 산업기술연구
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• 제17권
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• pp.79-85
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• 1997

This paper describes a control for the high performance induction motor drive system with a wide speed operating range and proposes a robust control method independent of motor parameter variation. For the operation below the rated speed, the high performance control is achieved by using the indirect field-oriented control with a speed sensor. In the high speed regain, the field weakening region with a large variation in motor parameters, the motor drive system can obtain the robustness to motor parameter variation by switchover to the direct field-oriented control. Also, the sensorless speed control using estimated speed is achieved in very high speed region that the utilization of speed sensor pulses is limited. And from experiments using high performance 32bit DSP for 2.2[kW] and 22[kW] laboratory induction motor drive systems, it is verified that the proposed opration algorithm provided a good performance.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3383-3388
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• 2007

To compare the sensor performance of AE leak diagnosis system which can measure valve leak conditions, AE activities such as RMS voltage level, AE signal trend, leak rate degree according to AE database, FFT spectrum were measured on valve of the simulated test system for power plant. AE activities were recorded and analyzed from various operating conditions including different temperature, pressure difference, valve size and fluid using both piezoelectric acoustic emission sensor and Pb-Free acoustic emission sensor. The results of this study are utilized to select the type of sensors, the frequency band for filtering and thereby to improve the signal-to-noise ratio for diagnosis or monitoring of valves in operation. As the final result of application study above, portable type leak diagnosis system by AE was developed. The outcome of the study can be definitely applied as a means of the diagnosis or monitoring system for energy saving and prevention of accident for power plant valve.

• 대한임베디드공학회논문지
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• 제8권2호
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• pp.103-109
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• 2013

Traditional implementation schemes for automotive electronic control units look simple, but the tradition schemes need so many coarse works to satisfy the user requirements regarding time constraints whenever their microprocessors are changed. Recently, a movement toward using middle-wares, such as OSEK operating system, has risen in automotive industry. In this paper, we describe how to use the features of operating systems to replace traditional firmware based softwares in points of views of services, such as multitask support, preemption, and realtime property. To show an example, we implemented a parking assistance system as a prototype.

• 한국정밀공학회지
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• 제21권7호
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• pp.92-100
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• 2004

A service robot is expected to be useful in indoor environment such as a hotel, a hospital and so on. However, many service robots are driven by wheels so that they cannot climb stairs to move to other floors. If the robot cannot use elevators. In this paper, the mobile manipulator system was developed, which can operate numeral buttons on the operating panel in the elevator. To perform this task, the robot is composed of an image recognition module, an ultrasonic sensor module and a manipulator. The robot can recognize numeral buttons and an end-effector in manipulator by the vision system. The Learning vector quantization (LVQ) algorithm is used to recognize the number on the button. The barcode mark on the end-effector is used to recognize the end-effector. The manipulator can push numeral buttons using informations captured by the vision system. The proposed method is evaluated by experiments.

• 전기전자학회논문지
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• 제19권2호
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• pp.142-147
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• 2015

본 논문에서는 자이로 센서와 가속도 센서로부터 얻은 정보를 보정 및 융합하여 자세를 추정하는 칼만 필터 기반 센서 융합 필터의 설계를 제안한다. 최근 센서 네트워크 기술의 발전으로 인해 센터 데이터의 융합 기술이 요구되고 있다. 본 논문에서는 필터의 비선형 시스템 모델을 Jacobian Matrix 연산을 통해 선형 시스템 모델로 변환하며, 오일러 적분을 통해 추정 값을 예측한다. 제안한 필터는 Xilinx 사의 Virtex-6 FPGA Board 를 이용하여 구현하였다. 구현한 필터는 74MHz 동작 주파수로 동작하며, 기존 필터들과 구현한 필터를 비교하여 추정 자세의 정확도 및 신뢰도를 확인하였다.

• Nuclear Engineering and Technology
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• 제55권3호
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• pp.814-826
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• 2023

Sensor faults in nuclear power plant instrumentation have the potential to spread negative effects from wrong signals that can cause an accident misdiagnosis by plant operators. To detect sensor faults and make accurate accident diagnoses, prior studies have developed a supervised learning-based sensor fault detection model and an accident diagnosis model with faulty sensor isolation. Even though the developed neural network models demonstrated satisfactory performance, their diagnosis performance should be reevaluated considering real-time connection. When operating in real-time, the diagnosis model is expected to indiscriminately accept fault data before receiving delayed fault information transferred from the previous fault detection model. The uncertainty of neural networks can also have a significant impact following the sensor fault features. In the present work, a pilot study was conducted to connect two models and observe actual outcomes from a real-time application with an integrated system. While the initial results showed an overall successful diagnosis, some issues were observed. To recover the diagnosis performance degradations, additive logics were applied to minimize the diagnosis failures that were not observed in the previous validations of the separate models. The results of a case study were then analyzed in terms of the real-time diagnosis outputs that plant operators would actually face in an emergency situation.

• Journal of Welding and Joining
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• 제13권1호
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• pp.156-166
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• 1995

Experimental models which are able to determine the deviation between weld line and weaving center by measuring the weld current during welding were proposed for the gas metal arc welding process. The models were used for developing a weld seam tracking system which controls the weaving speed of a welding torch. However, it was revealed that the tracking result of the system is affected by the welding conditions. Thus an arc sensor system was developed by using fuzzy control approach for overcoming the difficulty of modelling the nonlinear process. The rule base and parameters of the fuzzy control system were determined on the basis of the results of experiments. This fuzzy control system has shown the successful tracking capability for the wide operating range of welding conditions.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1440-1442
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• 2007

A high-voltage motor has had many problems due to its frequent startup, standstills and occasions of long period operation. As for a solution to the problem, many advanced countries have developed an on-line insulation diagnosis sensor and a same type of system and put them in use. Recently, even in the domestic market, a ceramic coupler has been developed and attempted to be applied in the field. This paper proposes an on-line insulation diagnosis system when operating a high-voltage motor along with the use of a domestic ceramic coupler. The proposed system is composed with a ceramic sensor, a PDMS-HM, and a Remote Monitoring System. As the result of comparing this system with a PDAS, which is an expensive full A/D method, the reliability of the system has been verified, and furthermore, it is in the process of being commercialized.

• 센서학회지
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• 제27권4호
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• pp.254-258
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• 2018

A Wi-Fi signal network (WSN) system is introduced in this paper. This system consists of several data-transmitting sensor modules and a data-receiving server. Each sensor module and the server contain a unique intranet IP address. A piezoelectric accelerometer with a bandwidth of 12 kHz, a 24-bit analog-digital converter with a sampling rate of 15.625 kS/s, a 32-bit microprocessor unit, and a 1-Mbps Wi-Fi module are used in the data-transmitting sensor module. A 300-Mbps router and a PC are used in the server. The system is verified using an accelerometer calibrator. The voltage output from the sensor is converted into 24-bit digital data and transmitted via the Wi-Fi module. These data are received by a Wi-Fi router connected to a PC. The input frequencies of the accelerometer calibrator (320 Hz, 640 Hz, and 1280 Hz) are used in the data transfer verification. The received data are compared to the data retrieved directly from the analog-to-digital converter used in the sensor module. The comparison shows that the developed system represents the original data considerably well. Theoretically, the system can acquire vibration signals from 600 sensor modules at an accelerometer bandwidth of 15.625 kHz. However, delay exists owing to software processes, multiplexing between sensor modules, and the use of non-real time operating system. Hence, it is recommended that this system may be used to acquire vibration signals with up to 10 kHz, which is approximately 70% of the theoretical maximum speed of the system. The system can be upgraded using parts with higher performance

• 해양환경안전학회지
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• 제28권2호
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• pp.346-353
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• 2022

최근 회전 회전기계의 건전성 관련 연구가 활발하게 진행중이며, 조선업의 대표적인 회전기계인 갠트리 크레인에도 이를 적용하고자 하는 연구가 활발하게 진행되고 있다. 하지만 조선업의 갠트리 크레인의 경우 상대적으로 낮은 RPM으로 구동되고 잦은 운전과 정지가 이루어지며 충격, 소음 등의 외부환경 인자가 측정 데이터에 영향을 크게 미쳐 오차를 발생시킬 수 있다. 본 연구에서는 조선업의 내업공정에서 사용되는 갠트리 크레인의 Hoist 모사장비를 제작하여, 운전조건(RPM) 변화와 데이터 획득 센서의 위치 차이가 획득 데이터에 미치는 오차를 통계적으로 분석하였다. 연구결과 상대적으로 낮은 운전조건에서는 센서 위치 차이에 따른 획득 데이터의 오차는 크게 발생하지 않았으나, 상대적으로 높은 운전조건에서는 획득 데이터의 오차가 크게 발생하는 것으로 확인하였으며, 회전기계의 데이터 획득 시 운전조건과 획득 센서위치가 획득 데이터에 영향을 미치는 것으로 확인하였다.