• Nuclear Engineering and Technology
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• v.51 no.7
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• pp.1791-1798
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• 2019

Instrumentation and Control (I&C) systems of nuclear power plants (NPPs) have been continuously digitalized. These systems have a critical role in the operation of nuclear facilities by functioning as the brain of NPPs. In recent years, as cyber security threats to NPP systems have increased, regulatory and policy-related organizations around the world, including the International Atomic Energy Agency (IAEA), Nuclear Regulatory Commission (NRC) and Korea Institute of Nuclear Nonproliferation and Control (KINAC), have emphasized the importance of nuclear cyber security by publishing cyber security guidelines and recommending cyber security requirements for NPP facilities. As described in NRC Regulatory Guide (Reg) 5.71 and KINAC RS015, challenge response authentication should be applied to the critical digital I&C system of NPPs to satisfy the cyber security requirements. There have been no cases in which the most robust response authentication technology like challenge response has been developed and applied to nuclear I&C systems. This paper presents a challenge response authentication mechanism for a Programmable Logic Controller (PLC) system used as a control system in the safety system of the Advanced Power Reactor (APR) 1400 NPP.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.2
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• pp.168-172
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• 2015

In general, open-loop fiber-optic gyroscopes (FOG) are less stable than closed-loop FOGs but they offer simpler implementation. The typical operation time of line-of-sight (LOS) stabilization systems is a few seconds to one hour. In this paper, a open-loop fiber optic gyroscope (FOG) for LOS applications is designed and implemented. The design goal is aimed at implementing a low cost, compact FOG with low Angle Random Walk (ARW) (< $0.03deg/\sqrt{h}$) and bias instability (< 0.25deg/h). The FOG uses an open-loop all-fiber configuration with 100M PM fiber wound on a small diameter spool. In order to get the design goal, digital signal processing techniques for signal detection, modulation control and compensation are designed and implemented in FPGA.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.910-912
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• 2014

최근 친환경과 헬스케어에 관심이 높아짐과 더불어 자전거 타는 것에도 관심이 높아지고 있다. 우리나라 정부에서도 거기에 발맞춰 자전거 전용도로를 전국에 설치하기고 했다. 처음 자전거를 배우기 시작해서 어느 정도 중심을 잡게 되면 보통 변속기를 사용하게 된다. 변속기를 사용하게 되면 승차 자들은 도로나 환경에 맞지 않게 미숙하게 변속을 하게 되며, 이에 따른 사용자의 조작에 사용하는 엄지 또는 검지의 손가락에 피로감이 높아지고 안전위험이 증가하게 되지만, 사용하는 개인들은 그것을 모르고 사용하는 경우가 많다. 본 연구에서는 자전거 사용을 활성화 하고 안전에 도움을 주고, 변속 조작에 사용하는 엄지 또는 검지 손가락 피로를 줄일 수 있는 디지털변속기를 개발하였다. 디지털변속기를 사용함으로 자전거 변속에 어려운 승차 자들을 위해 디지털 변속을 사용하므로 서 주행효율을 개선하고, 안전하게 자전거를 사용할 수 있을 것으로 사료된다. 승차 자가 속도 및 구배 정확하지 않는 변속에 의한 피로가 누적되어 하체에 무리가 많이 가게 되어서, 이로 인해 사고율도 높아 질수 있다. 기존 변속에 의한 문제점들을 해결하여 자전거의 운용을 효율성과 편의성을 개선하여, 안전 주행이 가능하게 하는 디지털 변속기를 개발 하였다.

• Journal of Sensor Science and Technology
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• v.20 no.3
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• pp.172-177
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• 2011

Finger patients can't use their hands because of the paralysis their fingers. Their fingers are recovered by rehabilitating training, and the rehabilitating extent can be judged by measuring the pressing force to be contacted with two fingers(thumb and first finger, thumb and middle finger, thumb and ring finger, thumb and little finger). At present, most hospitals have used a thin plastic-plate for measuring the two-finger grasping force, and we can only judge that they can grasp the plate with their two-finger through it, because the plate can't measure the two-finger grasping force. But, recently, the force measuring system for measuring two-finger grasping force was developed using three-axis force sensor, but it is very expensive, because it has a three-axis force sensor. In this paper, two-finger force measuring system with a one-axis force sensor which can measure two-finger grasping force was developed. The one-axis force sensor was designed and fabricated, and the force measuring device was designed and manufactured using DSP(Digital Signal Processing). Also, the grasping force test of men was performed using the developed two-finger force measuring system, it was confirmed that the grasping forces of men were different according to grasping methods, and the system can be used for measuring two-finger grasping force.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.8
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• pp.1540-1546
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• 2017

Digital image processing is widely used in various fields including the military, medical, image recognition system, robot and commercial sectors. But in the process of acquiring and transmitting digital images, noise is generated by various external causes. There are various types of general noise depending on the cause and form, but AWGN and impulse noise is one of the leading methods. Removing noise during image processing is essential to the pre-treatment process such as segmentation, image recognition and characteristic extraction. As such, this paper suggests an algorithm that distinguishes the non-edge area and edge area using the Canny edge to apply different filters to different areas in order to effectively remove noise from the image. To verify the effectiveness of the suggested algorithm, it was compared against existing methods using zoom images, edge images and PSNR(peak signal to noise ratio).

• Journal of IKEEE
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• v.4 no.2 s.7
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• pp.266-273
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• 2000

A frequency model of an OCXO (Oven Controlled X-tal Oscillator) is suggested to implement a holdover algorithm in a DP-PLL (Digital Processing-Phase Locked Loop) system. This model is presented simply with second order polynomials with respect to temperature and aging of the OCXO. The model parameters are obtained from experimental data by applying the LSM (Least Squared Method). A holdover algorithm is also suggest using the frequency model. The obtained model is verified to simulate the holdover algorithm with experimental phase data due to variation of temperature.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.1
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• pp.28-33
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• 2009

In the research of speech recognition, locating the beginning and end of a speech utterance in a background of noise is of great importance. The conventional methods for speech endpoint detection are based on two simple time-domain measurements-short-time energy, and short-time zero-crossing rate, which couldn't guarantee the precise results if in the low signal-to-noise ratio environments. This paper proposes a novel approach that finds the Lyapunov exponent of time-domain waveform. This proposed method has no use for obtaining the frequency-domain parameters for endpoint detection process, e.g. Mel-Scale Features, which have been introduced in other paper. Accordingly, this algorithm is low complexity and suitable for Digital Isolated Word Recognition System.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.2
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• pp.52-60
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• 2009

This paper proposes a digital controller for a nonlinear multi-input/multi-output(MIMO) system with time-delayed input. A nonlinear system with multi-input time delay is discretized using Taylor's discretization method, and the discretized system can be converted into a general nonlinear system. Consequently, general nonlinear controller synthesis can be applied to the discretized time-delay system We adopted MAC controller synthesis and verified the performance of the proposed method by conducting computer simulations. The results of the simulation showed that the proposed controller synthesis performs well and the proposed method is useful for controlling a nonlinear time-delay system.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.53.1-53
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• 2001

We have used many Instrumentations to acquire the performance data of vehicles for many years. but these could not satisfied with environment specifications (vibration, shock, temperature) and data processing speed to applicate the performance test for armored military vehicles because of having developed as a common vehicles/fixed installation equipments. So new rugged embedded measurement system required to do large data acquisition and high processing speed (Maximum sample rate : 1.25MHz/ch) with rugged environment specifications. We have developed embedded measurement system by using PXI(PCI eXtension for Instrumentation)bus interface which were composed of stand alone controller and versatile data acquisition boards(analog, digital, vision ...

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.6
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• pp.583-588
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• 2015

Flexible tactile sensors can provide valuable feedback to intelligent robots regarding the environment around them. This is especially important when robots such as, service robots share a workspace with humans. This paper presents a contact force measurement algorithm of a flexible tactile sensor. This sensor is manufactured by a direct-writing technique, which is one 3D printing method, using multi-walled carbon nano-tubes. An analog signal processing circuit has been designed and implemented to reduce noise contained in the sensor output. In addition, a digital version of the Butterworth filter was implemented by software running on a microcontroller. Through various experiments, characteristics of the sensor system have been identified. Based on three traits, an algorithm to detect the contact and measure the contact force has been developed. The entire system showed a promising prospect to detect the contact over a large and curved area.