• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.1 s.343
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• pp.65-70
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• 2006

An image sensor has limited dynamic range while the human eye has logarithmic response over wide range of light intensity. Although the sensor gain can be set high to identify details in darker area on the image, this results in saturation in brighter area. The gamma correction is essential to fit the human eye response. However, the digital gamma correction degrades image quality especially for darker area on the image due to the limited ADC resolution and the dynamic range. This Paper proposes a CMOS image sensor (CIS) with a nonlinear analog-to-digital converter (AU) which performs analog gamma correction. The CIS with the proposed nonlinear analog-to-digital conversion scheme was fabricated with a $0.35{\mu}m$ CMOS process. The analog gamma correction using the proposed nonlinear ADC CIS provides the 2.2dB peak-signal-to-noise-ratio(PSM) improved image qualify than conventional digital gamma correction. The PSNR of the image obtain from the digital gamma correction is 25.6dB while it is 27.8dB for analog gamma correction. The PSNR improvement over digital gamma correction is about $28.8\%$.

• Journal of the Korea Computer Graphics Society
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• v.19 no.4
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• pp.13-22
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• 2013

A motion capture system is widely used in movies, computer game, and computer animation industries because it allows for creating realistic human motions efficiently. The inertial motion capture system has several advantages over more popular vision-based systems in terms of the required space and cost. However, it suffers from low accuracy due to the relatively high noise levels of the inertial sensors. In particular, the accelerometer used for measuring gravity direction loses the accuracy when the sensor is moving with non-zero linear acceleration. In this paper, we propose a method to remove the linear acceleration component from the accelerometer data in order to improve the accuracy of measuring gravity direction. In addition, we develop a simple method to calibrate the joint axis of a link to which an inertial sensor belongs as well as the position of a sensor with respect to the link. The calibration enables attaching inertial sensors in an arbitrary position and orientation with respect to a link.

• Journal of Korean Society of Transportation
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• v.25 no.2 s.95
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• pp.157-165
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• 2007

In this research, a vertical alignment analysis algorithm was developed. The developed algorithm used acquired data from a vehicle with multiple sensors such as a global positioning system (GPS) an inertial navigation system (INS), and a distance measuring unit (DMI) to collect information about vehicle position and altitude. The vertical alignment analysis algorithm includes the identification of vertical tangent sections, the beginning and ending points of vertical curves, and the calculation of length of vortical curves. Also, the algorithm can help build models for vertical tangent sections and vertical curve sections. In order to verify the algorithm, a field survey was conducted at an actual highway section and the result of the field survey was compared to a highway CAD drawing.

• Journal of the Korean Magnetics Society
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• v.15 no.1
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• pp.48-52
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• 2005

This paper describes a current sensor for precision current measurement of an electronic watt-hour meter that is going to install in houses in the future. As the current sensor is based on an cored principle (the Rogowski principle) it is not subject to usual limitations of saturation and non-linearity of general current transformers. An advantage of the developed current sensor is that non-linearity error in low current range is improved and the construction can be kept simple using an air core. We present a magnetic field analysis of the sensor using a finite-element solver. We compared the measured values versus the calculated values.

• Journal of IKEEE
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• v.19 no.2
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• pp.142-147
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• 2015

In this paper, a Kalman filter-based sensor fusion filter that measures posture by calibrating and combining information obtained from acceleration and gyro sensors was proposed. Recent advancements in sensor network technology have required sensor fusion technology. In the proposed approach, the nonlinear system model of the filter is converted to a linear system model through a Jacobian matrix operation, and the measurement value predicted via Euler integration. The proposed filter was implemented at an operating frequency of 74 MHz using a Virtex-6 FPGA Board from Xilinx Inc. Further, the accuracy and reliability of the measured posture were validated by comparing the values obtained using the implemented filters with those from existing filters.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.422-425
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• 2006

본 연구는 도체주변에 감겨진 광섬유 코일에 따라 선형편광축이 자기장에 의해 회전하는 Faraday Effect를 이용한 GIS(Gas Insulated Switchgear,이하 GIS) 용 광 전류센서의 구성과 DAQ(Data Acquisition,이하 DAQ)보드를 장착한 PC를 이용하여 실시간 데이터 취득, 분석 그리고 저장을 동시에 수행하였다 광원은 1310[nm]의 레이저 다이오드를 이용하였다. 센서부는 GIS에 맞게 원형으로 제작하였고 $9/125[{\mu}m]$규격 단일모드의 일반 통신용 광섬유를 지름 31[cm]의 센서부 코어에 20[회] 감아 설치하였다. PC기반의 실시간 데이터 분석 프로그래밍은 NI사의 Labview를 이용하여 코딩하였으며 PD(Photo Diode,이하 PD)의 전기적인 신호는 터미널 블록을 거쳐 NI사의 16bit DAQ M시리즈를 이용하여 수집되어진다. 직접 코딩한 프로그램을 이용하여 $700A\sim1400A$ 측정한 출력값 선형적인 증가추세를 보여주었다. 또한 OCS(Oscilloscope,이하 OCS)를 이용한 측정시스템과의 출력신호 및 정밀도를 비교 검토하였다. 그리고 Labview에서 지원하는 Web Tool기능을 이용하여 Web기반의 원거리 측정에서도 안정된 출력을 보여주었다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.276-277
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• 2007

본 논문에서는 미량의 세포를 포함한 용액 내에서 세포의 산소호흡량을 측정하기 위해 FEP(Fluorinated Ethylene Propylene)를 멤브레인으로 사용한 Clark-type 센서를 제안하였다. 제안된 Clark-type 센서는 3-전극 시스템을 구성하는 유리 기판, 산소를 선택적으로 투과 시키는 FEP 멤브레인과 세포를 담을 수 있는 PDMS reservoir로 구성된다. 산소 센서의 3-전극 시스템에서 작업 전극과 상대 전극으로는 Au, 기준 전극으로는 Ag/AgCl을 사용하였다. 기준 전극은 Ag 전극을 0.1M KCl/Tris-HCl 용액에서 chlorination하여 표면에 AgCl이 형성되도록 하였고, OCP(Open Circuit Potential) test를 수행한 결과 2시간 동안 안정적인 OCP 특성을 보여 좋은 내구성을 가짐을 확인하였다. 또한, 산소 유무에 따른 cyclic voltammetry 그래프의 차이를 확인하고, amperometry로 감도 및 반응 시간, 선형성을 측정/분석하였다. 제작된 산소 센서는 40초의 90% 반응 시간과 0.994의 아주 좋은 선형 상관계수를 보여주었다.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.11 no.2
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• pp.92-96
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• 2006

NLPCA(Nonlinear Principal Component Analysis) is a novel technique for multivariate data analysis, similar to the well-known method of principal component analysis. NLPCA operates by a feedforward neural network called AANN(Auto Associative Neural Network) which performs the identity mapping. In this work, a sensor fault detection system based on NLPCA is presented. To verify its applicability, simulation study on the data supplied from risk management system is executed.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.4
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• pp.363-372
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• 2005

This paper presents an improved sensorless vector control system for high performance induction motor drives fed by a matrix converter with non-linearity compensation. The nonlinear voltage distortion that is caused by commutation delay and on-state voltage drop in switching devices is corrected by a new matrix converter model. A Reduced Order Extended Luenberger Observer (ROELO) is employed to bring better response in the whole speed operation range and a method to select the observer gain is presented. Experimental results are shown to illustrate the performance of the proposed system.

• Journal of Internet of Things and Convergence
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• v.9 no.2
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• pp.61-69
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• 2023

In recent years, due to heightened environmental awareness, Electric Power Steering (EPS) has been increasingly adopted as the steering control unit in manufactured vehicles. This has had numerous benefits, such as improved steering power, elimination of hydraulic hose leaks and reduced fuel consumption. However, for EPS systems to respond to actions, sensors must be employed; this means that the consistency of the sensor's linear variation is integral to the stability of the steering response. To ensure quality control, a reliable method for detecting defects and assessing linearity is required to assess the sensitivity of the EPS sensor to changes in the internal design characters. This paper proposes a data-driven defect and linearity assessment monitoring system, which can be used to analyze EPS component defects and linearity based on vehicle speed interval division. The approach is validated experimentally using data collected from an EPS test jig and is further enhanced by the inclusion of a Graphical User Interface (GUI). Based on the design, the developed system effectively performs defect detection with an accuracy of 0.99 percent and obtains a linearity assessment score at varying vehicle speeds.