• Journal of applied mathematics & informatics
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• v.9 no.1
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• pp.231-238
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• 2002

In this paper, we study cyclic codes detecting a subclass of close-closed loop bursts viz. low-density close-closed loop bursts. A subclass of CT close-closed loop berets called CT low-density close-closed loop bursts is also studied.

• Journal of the Korean Society of Industry Convergence
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• v.15 no.3
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• pp.79-82
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• 2012

Aim of this study is to investigate the dimensional characteristics of the weft knitted fabrics with Bamboo knitted yarn. This Bamboo knitted yarn was made of the biodegradability fiber. The structure of weft knitted fabrics that was utilized for this study is the plain stitch, which is the most basic structure among all weft knitted fabrics. The loop density, courses density, and wales density are more increased as the loop length is shorter. The loop density increased as pre-treatment process and dyeing process progressed after dry treatment process, and on the contrary, the heat setting process made it decreasing. After the dyeing process proceed, the loop density and the course density were displayed the highest values. When the knitted fabrics were fully relaxed, the loop density was $2000/in^2$, the courses density was 52/in, the wales density was 39/in.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.237-242
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• 2000

The areal recording density of HDD(Hard Disk Drive) has been increasing by about 60% a year. In order to achieve high areal density, less track pitch is expected and more servo bandwidth is required. Dual stage actuator and servo controller for HDD have been suggested for achieving high track density as a possible solution. Dual-loop servo system is generally classified into a two-input-two-output system, but if we use an estimator for a two-input-two-output system, it can be converted into two input one output system. Since we can't control the dual stage servo system by the classical method, it requires a special technique; for example, Parallel Loop System, Master-Slave Loop System, Decoupled Master-Slave Loop System, and Dual Feedback Loop System. In this paper, we performed experimental evaluations of several types of control algorithm. Further experiments will be made in the future.

• Textile Coloration and Finishing
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• v.11 no.6
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• pp.51-58
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• 1999

The dimensional properties on polyester warp knitted fabrics with various lengths of underlap were studied. The results indicated that loop density increased with decreasing loop length and loop density of satin warp knitted fabric are a little higher than that of reverse satin warp knitted fabrics at a constant loop length. As the distance of underlap becomes shorter, the weight per unit area and thickness increases, the bulkiness decreases and the shrinkage of knitted fabrics become larger toward wale in satin warp knitted fabric and toward the course in reverse satin warp knitted fabric.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.1978-1987
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• 2014

Power requirement to the induction heating system varies during the heating process. A closed loop control is required to have a smooth control over the power. In this work, a constant frequency pulse density modulation based power tracking control scheme for domestic induction heating system is developed using the Fuzzy Logic Controller. In the conventional power modulation schemes, the switching losses increase with the change in the load. The proposed pulse density modulation scheme maintains minimum switching losses for the entire load range. This scheme is implemented for the class-D series resonant inverter system. Fuzzy logic controller based power tracking control scheme is developed for domestic induction heating power supply for various power settings. The open loop and closed loop simulation studies are done using the MATLAB/Simulink simulation tool. The control logic is implemented in hardware using the PIC16F877A microcontroller. Fuzzy controller tracks the set power by changing the pulse density of the gate pulses applied to the inverter. The results obtained are used to know the effectiveness of the fuzzy logic controller to achieve the set power.

• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.4
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• pp.107-112
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• 2001

Laser Thomson scattering measurements of electrom temperature and density in a neutral loop discharge (NLD) plasma were performed in order to reveal the electron behavior around the neutral loop (NL). The experimental results were examined by using a simulation model that included effects of a three dimensional electromagnetic field with spatial decay of the RF electric field, and the limitation of the spatial extent of the electron motion and collision effect. From the experiments and modeling of the electron behavior, it was found that NLD plasma posses the electron temeprature $T_{e}$ and density ne peaks around the NL is essential for the formation of plasma. Also, the optimum condition of plasma production could be simply estimated by the calculation of $U_{av}$ and $F_{0}$././.

• Journal of Power Electronics
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• v.15 no.1
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• pp.65-77
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• 2015

Resonant converters are well suited for induction heating (IH) applications due to their advantages such as efficiency and power density. The control systems of these appliances should provide smooth and wide power control with fewer losses. In this paper, a simple phase locked loop (PLL) based variable duty cycle (VDC) pulse density modulation (PDM) power control scheme for use in class-D inverters for IH loads is proposed. This VDC PDM control method provides a wide power control range. This control scheme also achieves stable and efficient Zero-Voltage-Switching (ZVS) operation over a wide load range. Analysis and modeling of an IH load is done to perform a time domain simulation. The design and output power analysis of a class-D inverter are done for both the conventional pulse width modulation (PWM) and the proposed PLL based VDC PDM methods. The control principles of the proposed method are described in detail. The validity of the proposed control scheme is verified through MATLAB simulations. The PLL loop maintains operation closer to the resonant frequency irrespective of variations in the load parameters. The proposed control scheme provides a linear output power variation to simplify the control logic. A prototype of the class-D inverter system is implemented to validate the simulation results.

• Journal of the Korean Society of Industry Convergence
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• v.3 no.4
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• pp.337-343
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• 2000

Physical properties of matt georgette knitted fabrics, which has been developed recently, were investigated to provide fundamental information for the textile industry. Dimensional characteristics were examined with three different loop lengths, where the plain knitted fabrics were knitted with cotton yam and polyester yarn. The matt georgette plain knitted stitch was fully relaxed after wet relaxation treatment at $130^{\circ}C$ for 30minutes and subsequent tumble dry treatment at $70^{\circ}C$ for 90minutes. As the treatment temperature of wet relaxation became higher and the loop length did shorter, all of stitch density, course density and wale density were increased with 31 of $K_1$ 8.3 of $K_2$ and 3.8 of $K_3$. Also, The higher value of $K_4$ could be obtain with shorter loop length. When the loop length became longer, the $K_4$ value was varied in a wide range with the treatment of wet relaxation and subsequent tumble dry.

• Korean System Dynamics Review
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• v.11 no.2
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• pp.5-28
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• 2010

The purpose of this paper is to review relationship between spatial characteristics of compact city and urban sustainabiliy from system dynamics perspective using causal loop analysis. It has been argued that spatial characteristics of compact city, high population density and mixed land use, are positively related to urban sustainability. However, research results that are not consistent with pros of compact city argument have been accumulated too. It is especially true when spatial characteristics of compact city are examined with regard to each dimension of sustainablility: economic, social, and environmental sustainability. Reviewing each dimension of sustainability with regard to spatial characteristics based on causal loop analysis, this paper provides more clear understanding on relationship between compact city and sustainability. Also this paper provides a base for system dynamics simulation for future study.

• Journal of the Korean Institute of Telematics and Electronics
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• v.19 no.3
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• pp.37-45
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• 1982

This paper is a sequel of the Part I paper[1] on the modified digital Costas loop. In this Part II we analyze the performance of the system in the presence of noise. It is shown that, when the input signal is corrupted by additive white Gaussian noise, the noise process in the loop becomes Rician as a result of the tan-1 (.) function of the phase error detector. Steady state probability density functions of phase errors of the first-and second-order loops have been obtained by solving the Chapman-Kolmogorov equation numerically. Also, the mean and variance of phase error in the steady state have been obtained analytically, and are compared with the results obtained by computer simulation.