• Proceedings of the KIEE Conference
• /
• 2005.07d
• /
• pp.2843-2845
• /
• 2005

This paper deals with the design of real-time embedded system using RTOS (real-time operating system) and SOPC (system on a programmable chip). It is, in general, known that RTOS has the problem of time delay caused by the multiple tasks and task management approach. Since the increase in time delay in real-time embedded system makes the overall system have the poor performance or the critical behavior of instability and unreliability, the method employed RTOS and SOPC is proposed to attack the above problems. The proposed system is implemented on the RC-motor controller and is verified by real experiment.

• Proceedings of the KIEE Conference
• /
• 2005.07a
• /
• pp.905-907
• /
• 2005

In this paper, we propose the system that can monitor and control the camera in the remote place using the PDA. The server PC attached to the PLC (Programmable Logic Controller) acquires the current status (On/Off) of the devices through the RS-232 serial communications. Also, the moving image frames captured from the wireless camera is compressed in the JPEG format and is stored in the server. The PDA, which is connected to the server through wireless internet, receives the data about the status of the devices and controls the devices according to the circumstances of them. Also, it can receive the images from the server simultaneously. So, we ran monitor and control the specified area in the remote place using the PDA through the wireless communication.

• Proceedings of the KIEE Conference
• /
• 2005.07d
• /
• pp.3117-3119
• /
• 2005

In this paper, we propose the system that can monitor and control the camera in the remote place using the PDA. The server PC attached to the PLC (Programmable Logic Controller) acquires the current status (On/Off) of the devices through the RS-232 serial communications. Also, the moving image frames captured from the wireless camera is compressed in the JPEG format and is stored in the server. The PDA, which is connected to the server through wireless internet, receives the data about the status of the devices and controls the devices according to the circumstances of them. Also, it can receive the images from the server simultaneously. So, we can monitor and control the specified area in the remote place using the PDA through the wireless communication.

• 제어로봇시스템학회:학술대회논문집
• /
• 1993.10a
• /
• pp.342-347
• /
• 1993

For a fast evolution, a memory-based implementation of a petri net is discussed. A sub-class petri net model called B-petri net is suggested to make a memory-based implementation feasible in a large size application. The suggested B-petri net is a binary-petri net since only a binary-typed decision, fork and join are allowed. The application of a B-petri nt is focused to a SFC(sequential function chart) program. The memory requirement, speed and computational load are compared with a petri net when they are implementated by a memory-based method.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10b
• /
• pp.601-604
• /
• 1996

It is well known that steam generator water level control at low power operation has many difficulties in a PWR (pressurized water reactor) nuclear power plant. The reverse process responses known as shrink and swell effects make it difficult to control the steam generator water level at low power. A new automatic control logic to remove the reverse process responses is proposed in this paper. It is implemented in PLC (programmable logic controller) and evaluated by using test equipment in Korea Atomic Energy Research Institute. The simulation test shows that the performance requirements is met at low power (below 15%). The water level control by new control logic is stabilized within 1% fluctuation from setpoint, while the water level by YGN 3 and 4 control logic is unstable with the periodic fluctuation of 25% magnitude at 5% power.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10b
• /
• pp.706-709
• /
• 1996

In this paper, an algorithm for PLC(Programmable Logic Controller) fault diagnosis system is proposed and experimentation is conducted with a PLC and a virtual plant. Wrong output backward tracking algorithm is proposed in order to find the external faults of PLC. And query with keywords of the fault systems and specially designed test sequence programs are used. We lay emphasis on the backward tracking algorithm to diagnose the faults of PLC. It is shown experimentally that the proposed algorithm can find the faults which a typical self diagnostics in the-commercially available PLC cannot.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.93-97
• /
• 2005

This paper proposes a design of stepper motor control in microstep driven mode using FPGA (Field Programmable Gate Array) for hardware implementation. The methods to drive stepper motor in microstep excitation mode are to control of the controlling currents in each phase windings of stepper motor with reference signals. These reference signals are used for controlling the current levels, the required variation of current levels with rotor position can be obtained from the ideal linear or sinusoidal approximations to the static torque-displacement ($T-{\theta}$) characteristic curve. In addition, the hardware implementation of stepper motor controller can be designed uses VHDL (Very high speed integrated circuits Hardware Description Language) and synthesis using an Altera FPGA, FLEX10K family, EPF10K20RC240-4 device as target technology and use MAX+PlusII program for overall development. A multi-stack variable-reluctance stepper motor of Sanyo Denki is used in the experiments.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2004.10a
• /
• pp.447-452
• /
• 2004

동기전동기를 처음 기동시킬 때는 유도전동기와 같이 동작하게 된다. 회전자가 고정자 자계에 거의 도달하였을 때 M 전류를 투입하게 되면, 회전자의 여자코일에 동기화 토크가 발생하게 된다. 그러나 동기화 토크의 부족은 회전자의 첫 동요 시, 회전자 각의 불안정을 야기하게 된다. 동기화 토크는 신속 정확한 동작 제어에 의해 회복될 수 있다. 더욱이 역률 100%의 안정도로 동작하기에는 어려운 부분이 있다. 그러므로 본 논문에서는 이러한 문제를 해결하기 위해 퍼지 추론 기법을 이용한 여자 전류 제어 시스템을 제안하였다. 그 주된 원리는 다양한 부하 조건하에서 부하각과 역률 100%의 동작점을 추정하고, 퍼지 추론 기법에 의해 여자 전류를 제어하는 것이다. 제안된 퍼지 제어기는 각종 특수 동작 명령어로 사용되는 마이크로프로세서형 PLC(Programmable Logic Controller)를 사용하여 구현되었으며, 전기자 전류를 감지하는 제어전압 보상기, 비교기, 그리고 쵸퍼회로로 구성된 기존의 제어기에 비해 성능이 우수하다. 이는 일련의 실험을 통해 역률 100%에서의 개선된 안정적인 동작이 가능함을 보여주었다.

• Review of KIISC
• /
• v.25 no.5
• /
• pp.26-36
• /
• 2015

PLC(Programmable Logic Controller)는 기반시설 운영 현장의 다양한 환경을 견딜 수 있도록 설계된 소규모 산업용 컴퓨터로써, 많은 제어시스템에서 사용되고 있다. 과거의 PLC가 장치 제어를 위한 목적으로 제한된 필수 프로그램만을 사용하였다. 하지만 최근의 PLC는 ethernet 등의 네트워크를 기반으로 다양한 IT 기술들이 적용되고 있다. PLC 기반의 제어시스템은 운영자 및 관리자에게 편의성을 제공하지만 여러 보안 취약점들이 내재되어 있을 수 있다. 취약점들이 공격자에게 노출되어 사이버 위협을 받을 경우, 심각한 보안 사고를 일으킬 수 있으므로, 이러한 취약점들을 찾고 보안 대책을 마련하여 적용하는 것이 필요하다. 그러나 PLC의 특성 및 운용 환경 등이 IT 장비들과는 상이한 점이 있어 IT 장비들을 위한 취약점 분석 방법을 그대로 PLC에 적용하는 것은 한계가 있다. 따라서, 본 논문에서는 PLC의 특성 및 운용 환경 등을 고려한 PLC 취약점 분석 방법에 대해서 제안하고자 한다.

• Proceedings of the KIEE Conference
• /
• 2005.10b
• /
• pp.331-333
• /
• 2005

In this paper, we implemented the monitoring and control of geothermal heating and cooling system using mobile devices. The main idea of this system is to provide the convenience if the system can be controled in remote place with monitoring using the mobile devices like PDA. Basically, the system consists of the Server-Client structure divided into two parts, one is PDA and PC, the other is PC and PLC(Programmable Logic Controller). The PDA, which is equipped with Windows CE as as, monitors the status of the devices (motors and sensors, etc) attached to PLC and controls them. This does the system to be controled by the commands, which we assume to control, with wireless transmission between PC and PLC. The PDA parts are responsible for monitoring and control the devices connected to the PLC, and the PC part which equipped with the application is to provide the relation between PDA and PLC. The Ladder Program is used to control the sequences of the PLC..