• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.4
• /
• pp.1278-1284
• /
• 2010

In this paper, we propose a new mura detection algorithm for TFT-LCD effectively, which is based on multi-point, 2-dimensional FFT. Since mura in TFT-LCD has a certain area shape, it is seen as a sin wave in a LCD line. Since shapes of mura can be seen a circle, horizontal oval, or vertical oval, it is shown that they can be detected by 2-dimensional FFT easily. Through simulation for test image, it is shown that proposed algorithm can detect various sizes of mura. The proposed algorithm can be utilized in automatic test equipment for effective TFT-LCD mura detection.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.8B
• /
• pp.787-795
• /
• 2002

This paper presents the architecture and the implementation of a 2K/4K/8K-point complex Fast Fourier Transform(FFT) processor for Orthogonal Frequency-Division Multiplexing (OFDM) system. The architecture is based on the Cooley-Tukey algorithm for decomposing the long DFT into short length multi-dimensional DFTs. The transposition memory, shuffle memory, and memory mergence method are used for the efficient manipulation of data for multi-dimensional transforms. Booth algorithm and the COordinate Rotation DIgital Computer(CORDIC) processor are employed for the twiddle factor multiplications in each dimension. Also, for the CORDIC processor, a new twiddle factor generation method is proposed to obviate the ROM required for storing the twiddle factors. The overall 2K/4K/8K-FFT processor requires 600,000 gates, and it is implemented in 1.8 V, 0.18 ${\mu}m$ CMOS. The processor can perform 8K-point FFT in every 273 ${\mu}s$, 2K-point every 68.26 ${\mu}s$ at 30MHz, and the SNR is over 48dB, which are enough performances for the OFDM in DVB-T.

• 제어로봇시스템학회:학술대회논문집
• /
• 2002.10a
• /
• pp.32.2-32
• /
• 2002

In this paper, an efficient FFT-based fault detection algorithm is proposed. In our proposed method, fault detection is accomplished by process similar to the conventional FFT-based fault detection. However, the proposed technique adopts fast algorithms for preprocessing, where the conventional operation such as averaging is replaced with recursive average operation that outperforms the former in computational cost. And, the proposed approach utilizes the feature vector with the small dimension, which is extracted from spectral components of the lower and upper sidebands around the fundamental frequency. The mean absolute difference (MAD) criterion is used to finally determine whether motor...

• Journal of the Korean Institute of Intelligent Systems
• /
• v.15 no.6
• /
• pp.682-687
• /
• 2005

Behavioral sequences of the medaka(Oryzias latipes) were investigated through an image system in response to medaka treated with the insecticide and medaka not treated with the insecticide, diazinon(0.1 mg/1). After much observation, behavioral patterns could be divided into 4 patterns: active smooth, active shaking, inactive smooth, and inactive shaking. These patterns were analyzed by 5 features: speed ratio, x and y axes projection, FFT to angle transition, fractal dimension, and center of mass. Each pattern was classified using decision tree. It provide a natural way to incorporate prior knowledge from human experts in fish behavior, The main focus of this study was to determine whether the decision tree could be useful in interpreting and classifying behavior patterns of the animal.

• Wind and Structures
• /
• v.38 no.1
• /
• pp.1-13
• /
• 2024

In order to effectively simulate nonstationary stochastic turbulent wind fields, four separation hybrid (SEP-H) models are proposed in the present study. Based on the assumption that the lateral turbulence component at one single-point is uncorrelated with the longitudinal and vertical turbulence components, the fluctuating wind is separated into 2nV-1D and nV1D nonstationary stochastic vector processes. The first process can be expressed as double proper orthogonal decomposition (DPOD) or proper orthogonal decomposition and spectral representation method (POD-SRM), and the second process can be expressed as POD or SRM. On this basis, four SEP-H models of nonstationary stochastic turbulent wind fields are developed. In addition, the orthogonal random variables in the SEP-H models are presented as random orthogonal functions of elementary random variables. Meanwhile, the number theoretical method (NTM) is conveniently adopted to select representative points set of the elementary random variables. The POD-FFT (Fast Fourier transform) technique is introduced in frequency to give full play to the computational efficiency of the SEP-H models. Finally, taking a long-span bridge as the engineering background, the SEP-H models are compared with the dimension-reduction DPOD (DR-DPOD) model to verify the effectiveness and superiority of the proposed models.

• Journal of Sensor Science and Technology
• /
• v.11 no.2
• /
• pp.67-76
• /
• 2002

We have presented a 2-dimensional fluxgate sensor with ferrite core, excitation, and pick-up coil. This fluxgate sensor system consists of a sensing element, driving circuits for excitation coil and signal processing for detecting second harmonic frequency component which is proportional to the DC magnetic to be measured. The sensor core is excited by a square waveform of voltage through the excitation coil of 80 turns. The second harmonic output of pick-up coil(x and y axis: 100 turns) is measured by FFT spectrum analyzer. This result is compared with output of PSD(phase sensitive detector) unit for detecting the second harmonic component. The measured maximum sensitivity is about 1580 V/T at driving frequency of 1.5 kHz and excitation current of 2 App. The nonlinearity of this system is measured about 2.3%(PSD) and about 1%(second harmonics of the pick-up). The angle error of the system is ${\pm}2$ %/FS.

• Korean Journal of Applied Biomechanics
• /
• v.15 no.4
• /
• pp.117-129
• /
• 2005

The purpose of this study was to characterize the impact shock wave and its attenuation, and the kinematic response of the lower extremity's joints to the impact shock during downhill running in which the lower extremity's extensor acts dominantly. For this study, fifteen subjects(mean age:$27.08{\pm}4.39$; mass:$76.30{\pm}6.60$; height:$177.25{\pm}4.11$) were required to run on the 0% grade treadmill and downhill grades of 7%, and 15% in random at speed of their preference. When the participant run, acceleration at the tibia and the sacrum and kinematic data of the lower extremity were collected for 20s so as to provide at least 5 strides for analysis at each grade. Peak impact accelerations were used to calculate shock attenuation between the tibia and sacrum in time domain at each grade. Fast Fourier transformation(FFT) and power spectral density(PSD) techniques were used to analyze impact shock factors and its attenuation in the frequency domain. Joint coordinate system technique was used to compute angular displacement of the ankle and knee joint in three dimension. The conclusions were drawn as fellows: 1. Peak impact accelerations of the tibia and sacrum in downhill run were greater than that of 0% grade run, but no significant between conditions. Peak shock of PSD resembled also in pattern of peak impact acceleration. The wave of impact shock attenuation between the tibia and sacrum decreased with increasing grade, but didn't find a significant difference between grade conditions. 2. Adduction/abduction, flexion/extention, and internal/external rotation of the ankle and knee joints at support phase between grade conditions didn't make much difference. 3. At grade of 7% and 15%, there were relationship between the knee of the flexion/extension movement and peak impact acceleration during heel strike and found also it in the ankle of plantar/dorsiflexion at grade of 15%.