• Journal of Electrical Engineering and information Science
• /
• 제2권3호
• /
• pp.22-28
• /
• 1997

In this paper, we propose an efficient multicast addressing scheme for he self-routing multistage networks. Using only N-bit routing header an the simple hardware logic, the new scheme can efficiently provides all point-to-multipoint connections in single pass through the multistage copy networks. We also designed a hardware logic of switching element to implementation of multicasting in ATM switches are performed.

• Journal of the Optical Society of Korea
• /
• 제6권2호
• /
• pp.21-26
• /
• 2002

Interferometric metrology with a null CGH(computer-generated hologram) is presented for measuring highly aspheric surfaces used in a large screen projection television system with high accuracy. The cubic spline surface model which works in a single-pass configuration with a refractive index of object space 0 is used for designing a null CGH. A hybrid null corrector with plano-concave lens in front of a CGH is presented to make the CGH easier to fabricate. Experimental results are presented to demonstrate the validity of the proposed technique.

• 제어로봇시스템학회논문지
• /
• 제16권5호
• /
• pp.440-445
• /
• 2010

This paper proposes a single accelerometer sensor control algorithm to mobile inverted pendulum, generally called 'Segway', and evaluates the performance of this system comparing to the conventional ones. The commercialized 'Prototype Segway-PT' is initially considered as a next-generation transport vehicle. However, this robot is operated by three gyroscopes and two accelerometers to control the posture and speed, and it requires the complex signal processing for fusing the two sets of data. As the result of this, the growth rate of market size of 'Segway' is slow because of its high price mainly. In this paper, the mobile inverted pendulum is operated by a single accelerometer to simplify the control system to lower the price. Low pass filter is one of the good sensors to reducing the variation of an accelerometer, but it has time delay. This time delay disturbs real-time mobile inverted pendulum control. Like this, other various algorithms are used for this system, but each one has its own weak point. So this paper proposes a new filtering method, median filter and EKF. Median filter is used to image processing to reject impulse elements like salt and pepper noise. As the major performance evaluation parameter for the accelerometer, the high-frequency to low frequency ratio from FFT (Fast Fourier Transform) is used. Effectiveness of the proposed algorithms has been verified through the real experiments and the results are demonstrated.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
• /
• pp.1480-1482
• /
• 2005

The major causes of power quality deterioration are harmonic current through semiconductor switching device, due to use of nonlinear loads such as diodes rectifier or thyristor rectifiers. In response to this concerns, this paper presents a new control method of single-phase active power filter(APF) for the compensation of harmonic current components in nonlinear loads. In order to make the complex calculation to be possible, the single-phase system that has two phases was made by constructing a imaginary second-phase giving time delay to load currents. In the conventional method, a imaginary-phase lagged to the load current T/4(here T is the fundamental cycle) was made. But in this proposed method, the new signal, which has the delayed phase through the filter, using the phase-delay property of low-pass filter, was used as the second phase. As this control method is applied to the system of single phase, an instantaneous calculation was done rather by using the rotating reference frames that synchronizes with source-frequency than by applying instantaneous reactive power theory that uses the conventional fixed reference frames.

• ETRI Journal
• /
• 제35권3호
• /
• pp.386-396
• /
• 2013

A 10-Gbit/s wireless communication system operating at a carrier frequency of 300 GHz is presented. The modulation scheme is amplitude shift keying in incoherent mode with a high intermediate frequency (IF) of 30 GHz and a bandwidth of 20 GHz for transmitting a 10-Gbit/s baseband (BB) data signal. A single sideband transmission is implemented using a waveguide-tapered 270-GHz high-pass filter with a lower sideband rejection of around 60 dB. This paper presents an all-electronic design of a terahertz communication system, including the major modules of the BB and IF band as well as the RF modules. The wireless link shows that, aided by a clock and data recovery circuit, it can receive $2^7$-1 pseudorandom binary sequence data without error at up to 10 Gbit/s for over 1.2 m using collimating lenses, where the transmitted power is 10 ${\mu}W$.

• 한국자동차공학회논문집
• /
• 제6권5호
• /
• pp.153-161
• /
• 1998

The knock in a spark ignition engine has been investigated to avoid the damage to the engine and unpleasant feeling caused by the pressure waves propagating across the combustion chamber. Knock intensity and knock onset angle were used as physical parameters to quantify the knock characteristics. The knock intensity is defined as a peak to peak value of the bank pass filtered combustion pressure signal and the knock onset angle is determined as the crank angle at which this signal exceeded the threshold level on each cycle. The cyclic variation of knock in four valve single cylinder engine was investigated with these two parameters. The location of autoignition was also examined by ion probes in the cylinder head gasket and squish region in the combustion chamber. For this measurement, a single cylinder engine was modified to accept the pressure transducer, 18 ion probes in the squish region and 8 ion probes in the specially designed PCB (Printed \ulcornerCircuit Board) cylinder head gasket.

• 한국해양공학회지
• /
• 제8권1호
• /
• pp.131-143
• /
• 1994

The BTA(boring and trepanning association) deep hole machining has an increasing demands because of its wide applications and its good productivity. The main feature of the BTA tools is that the tool cutting edges are unsymmetrically located on the boring head. This provides a stabilizing cutting force resultant necessary for self guidance of the boring head. The BTA tools are capable of machining for having a large length to diameter ratio in single pass. A study of the accuracy and surface finish of holes produced would reveal quite useful information regarding the process. This study deals with the experimental results obtained during BTA machining on SM55C, SM45C steel under differnt machining conditions.

• Journal of Power Electronics
• /
• 제15권6호
• /
• pp.1664-1672
• /
• 2015

This paper proposes a series arc fault detection algorithm which incorporates peak voltage and harmonic current detectors for single-phase boost power factor correction (PFC) rectifiers. The series arc fault model is also proposed to analyze the phenomenon of the arc fault and detection algorithm. For arc detection, the virtual dq transformation is utilized to detect the peak input voltage. In addition, multiple combinations of low- and high-pass filters are applied to extract the specific harmonic components which show the characteristics of the series arc fault conditions. The proposed model and the arc detection method are experimentally verified through a boost PFC rectifier prototype operating under the grid-tied condition with an artificial arc generator manufactured under the guidelines for the Underwriters Laboratories (UL) 1699 standard.

• International Journal of Fluid Machinery and Systems
• /
• 제2권3호
• /
• pp.239-247
• /
• 2009

Sewage pumps are designed with a wide flow channel by, for example, sacrificing some efficiency and reducing the number of blades, in order to prevent plugging with foreign bodies. However, the behavior of foreign bodies which actually flow into a pump is extremely complex, and there are questions about whether the presumed foreign bodies will actually pass through. This paper proposes a new type of sewage pump impeller designed to further improve pump efficiency and performance in passing foreign bodies. This sewage pump impeller has a structure in which the suction flow channel of a closed type non-clog pump is wound in a helical spiral. The focus of this research was to investigate pump performance and internal flow in this single blade sewage pump impeller. The results clearly indicated the following facts: The developed sewage pump impeller exhibits high efficiency over a wide range of flow rates; internal flow of the pump is very complicated; and the internal flow state varies greatly when the flow rate changes.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
• /
• pp.117-120
• /
• 1993

In this paper, a novel DC link voltage control scheme for a single-phase PWM converter is proposed. The main idea of the control scheme is eliminating the effect of dc link voltage harmonics by using power balance of input side and output side. With the proposed strategy, faster transient response than that of conventional method using low-pass filter can be obtained. In addition, a half period current control, based at equal switching frequency, is proposed. The validity of the proposed scheme is verified by simulation results for GTO PWM converter system.