Sikyung Kim

A bifunctional utility connected photovoltaic system with power factor correction and UPS facility

In this paper, a novel utility connected photovoltaic power generation system with unity power factor and uninterruptable power system facility and its control strategy are proposed. The proposed photovoltaic (PV) system is connected in parallel between the utility and load. The PV system provides an uninterruptable voltage to the load, a maximum power tracking to solar array, and power factor correction to the utility. The proposed system has the following advantages compared with the conventional utility connected PV system: harmonic elimination function; feeding the photovoltaic energy to the utility; and providing the uninterruptible power source battery to the load. In the case where the photovoltaic array system is in a state of poor power generation, the battery and capacitor of the PV system are charged by a three phase utility source and the inverter in the PV system only provides the reactive current to eliminate the harmonic current exited on the utility. In the normal operation mode, the PV system supplies active power to the load and reactive power to the utility in order to maintain the unity power factor and to regulate AC load voltage.

Abnormal Gait Detection Using Discrete Fourier Transform

Detection of gait characteristics has found considerable interest in fields of biomechanics and rehabilitation sciences. In this paper an approach for abnormal gait detection employing discrete Fourier transform (DFT) analysis has been presented. The joint angle characteristics in frequency domain have been analyzed and using the harmonic coefficients, recognition for abnormal gait has been performed. The experimental results and analysis represent that the proposed algorithm based on DFT can not only reduce the gait data dimensionality effectively, but also lightens the computation cost, with a satisfactory distinction. In order to make the algorithm more generic, a mean square error (MSE) analysis is also presented. Future work will be the expansion of the detection introduced in this system to include abnormality detection instead of just an abnormal or normal detection that would prove to be a valuable addition for use in a variety of applications, including unobtrusive clinical gait analysis, automated surveillance etc.

Load sharing operation of a 14 kW photovoltaic/wind hybrid power system

In this paper, a design procedure for photovoltaic/wind hybrid power generation system is presented. The hybrid system is composed of a DC/DC converter for photovoltaic energy conversion, a DC/DC converter for wind energy conversion, a four switch IGBT inverter converting the combined DC power to the AC power and a backup power battery. Here, it is very important to select the desired battery size to meet the stable output and economic cost aspect since this system utilizes a fluctuating and finite energy resource. The purpose of this paper is to develop a sizing method for the PV/wind energy hybrid system with load sharing operation. The method demonstrates a simple tool to determine the desired battery size that satisfies the energy demand from the user with the photovoltaic and wind natural source. The proposed method is verified on a 14 kW hybrid power system including a 10 kW PV generator and a 4 kW wind generator established in Cheju island, Korea.

Novel Parameter Estimation Method for Chirp Signals Using Bowtie Chirplet and Discrete Fractional Fourier Transform

A new parameter estimation method for linear chirp signal is proposed. This method utilizes the Discrete Fractional Fourier Transform (DFRFT) along with Bowtie Chirplet Transform to estimate the amplitude and phase parameters of multi-component chirp signals. DFRFT is used for estimating amplitude parameter whereas the chirp rate and initial frequency are estimated using Chirplet Transform. Performance of the proposed method in noise is analyzed by Monte- Carlo simulation for different Signal to Noise Ratio (SNR). Good performance was achieved at SNR as low as -10 dB.

Face Recognition Using 3D Head Scan Data Based on Procrustes Distance

Recently face recognition has attracted significant attention from the researchers and scientists in various fields of research, such as biomedical informatics, pattern recognition, vision, etc due its applications in commercially available systems, defense and security purpose Face recognition presents a very challenging problem in real application in computer vision and pattern recognition due to variation of face. A large number of face recognition algorithms, along with their modifications are available over the past three decades. In this paper a practical method for face reorganization utilizing head cross section data based on Procrustes analysis is proposed. Firstly, a number of head cross section data were extracted from 3D head scanner along sagittal plane for eight different subjects. After extracting 3D head cross section data a comparison analysis were performed utilizing Procrustes distance to differentiate their face pattern from each other. The performance analysis of face recognition was analyzed based on K nearest neighbor classifier. The experimental results presented here verify that the proposed method is considerable effective.

Abnormal Gait Detection Using Discrete Wavelet Transform in Fourier Domain

Detection of gait characteristics has found considerable interest in fields of biomechanics and rehabilitation sciences. In this paper an approach for abnormal gait detection employing Discrete Fourier Transform (DFT) followed by Discrete Wavelet transform (DWT) analysis has been presented. The joint angle characteristics in frequency domain have been analyzed and using the harmonic coefficient recognition for abnormal gait has been performed. A classification of gaits has been attempted using k-means clustering based on the data acquired from DFT and DWT. Future work will be the expansion of the detection introduced in this system to include abnormality detection instead of just an abnormal or normal detection that would prove to be a valuable addition for use in a variety of applications including unobtrusive clinical gait analysis, automated surveillance etc.

A Last Design with Uniform Foot Pressure Free Form Deformation

The human foot has different shapes according to sex and age. It is an essential factor to consider the individual foot shape and characteristics. The conventional last design method does not take care of these factors and it just depended on the method based on bare eyes and skilful hands. Those results in the last design are not proper for the human foot. To solve these problems the last end shoe has to be designed based on the 3dimension (3d) foot shape and foot pressure data. This paper presents a 3d last design system utilizing a Uniform Foot Pressure Free Form Deformation (UFPFFD). The proposed UFPFFD is operated on the rule of foot pressure unbalance analysis and FFD. The deformation factor of the UFPFFD is constructed on the FFD lattice with the foot pressure unbalance analysis on the measured 3d foot shape..

Estimation of Uncertainties in 3D Motion Analysis Data

A complete understanding of motion is important for assisting clinicians and engineers in the prevention, diagnosis, and treatment of people with physical disorders. According to an ISO standard, three dimension (3D) motion measurements are always related to some errors and therefore always only obtained values. For 3D motion measurement systems, when applied to measuring human motion, motion data is sometimes reported with a standard error of measurement reflecting the uncertainty of the measurement caused by this skin movement artifact during motion as well as system error and marker noise. This lack of information seriously limits the ability to investigate motion analysis for the researchers. The purpose of this paper is to quantify the uncertainty caused by skin movement artifact as well as sensor noise and measurement error of the motion analysis system. We present a method for incorporating the uncertainty of the matching between a model of the calibration device (3D robot) and measurements, obtained with a motion analysis system (Optotrak Certus), in a Kalman filter.

Automatic 3D Wig Generation Method Using FFD and Robotic Arm

In this paper, a novel approach is proposed to generate an automatic 3D wig which can take place of the manual conventional system. To establish this approach, we used the robotic arm which takes seven landmark points used on FFD (Free form deformation) algorithm to produce human 3d shape from seven 3d landmarks points. Earlier most of the researcher made wig using the scanner and process it using various softwares. However, these methods are the long process to make the 3d wig and they could not take actual head shape because of hair. Our system works for the head with hair to give the original head shape. Only seven landmark points can make custom wig quickly and efficiently.

Mobile ECG Measurement System Design with Fetal ECG Extraction Capability

In this paper, the abdomen ECG(AECG) is employed to measure the mothers ECG instead of the conventioanl thoracic ECG measurement. The fetus ECG signal can be extracted from the AECG using an algorithm that utilizes the mobile fetal ECG measurement platform, which is based on the BLE (Bluetooth Low Energy). The algorithm has been implemented by using a replacement processor processed directly from the platform BLE instead of the large statistical data processing required in the ICA(Independent component analysis). The proposed algorithm can be implemented on a mobile BLE wireless ECG system hardware platform to process the maternal ECG. Wireless technology can realize a compact, lowpower radio system for short distance communication and the IOT(Intenet of Things) enables the transmission of real-time ECG data. It was also implemented in the form of a compact module in order for mothers to be able to download and store the collected ECG data without having to interrupt or move the logger, and later link the module to a computer for downloading and analyzing the data. A mobile ECG measurement prototype is manufactured and tested to measure the FECG for pregnant women. The experimental results verify a real-time FECG extraction capability for the proposed system. In this paper, we propose an ECG measurement system that shows approximately 91.65% similarity to the MIT database and the conventional algorithm and SNR performance about 10% better.