• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.4
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• pp.21-27
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• 2019

Composite motor cases fabricated by the filament winding method are structurally weak in the dome when they are required to withstand the internal pressure of the combustion gas. In this study, a finite element analysis is conducted to compare the burst pressure of a composite dome according to the variation of the pressure distribution ratio(PDR). The performance of the composite motor case was compared quantitatively by calculating the stress on the inner and outer dome surfaces and metal boss volume. As a result, the critical point of the failure mode was observed at a PDR between 2.5 and 3.0. A design at a PDR of 2.5­-3.5 can reduce the weight of metal boss without fluctuation in the burst pressure of the combustion motor case. Moreover as the design reference value changes according to the dome shape and opening size, further analysis and testing are necessary.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.7
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• pp.83-91
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• 1993

A ghost cancelling method using the multiplicationless adaptive multipath channel identification is proposed. The IIR filter and the LMS algorithm are used for ghost cancelling. The coefficients of IIR filter are obtained by multipath channel identification. The LMS algorithm which is simple relatively is used as the adaptive algorithm. An MPS is selected as the reference signal and it is used as the input of the adaptive algorithm for the multipath channel identification. If an MPS is not exist, the horizontal syne, and color burst signal can be used as the reference signal. Improving of accuracy of the ghost cancelling in the presence of the phase variation in the multipath channel, a complex processing are also performed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.4
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• pp.298-304
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• 2013

Channel attenuation must be taken into account when designing Time Division Multiple Access(TDMA) communication systems. In addition, Automatic Gain Control (ACG) is a requirement in satellite communication systems in order to form a stable network regardless of rapidly changes in channel environment. In this study, we present an AGC with possible real-time application to time slots in satellite TDMA communication systems. A satellite TDMA system was designed and implemented in order to test the performance of the proposed real-time AGC, and the system's BER (Bit Error Rate) was found by applying the proposed AGC algorithm. These results can be expected to be of high value in improving the stability of satellite TDMA communication systems in the future.

• Journal of IKEEE
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• v.14 no.2
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• pp.1-8
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• 2010

In this paper, Green Mode Power IC is designed to reduce the standby power. The proposed and designed IC works for the Switch Mode Power Supply(SMPS) and has the function of PWM. To reduce the unnecessary electric power, burst mode and skip mode section are introduced and controlled by external power MOSFET to diminish the standby power. The proposed IC is designed and simulated by KEC 30V-High Voltage 0.5um CMOS Process. The structure of proposed IC is composed of voltage regulator circuit, voltage reference circuit, UVLO(Under Voltage Lock out) circuit, Ibias circuit, green circuit, PWM circuit, OSC circuit, protection circuit, control circuit, and level & driver circuit. Measuring the current consumption of each block from the simulation results, 1.2942 mA of the summing consumption current from each block is calculated and ot proved that it is within the our design target of 1.3 mA. The current consumption of the proposed IC in this paper is less than a half of conventional ICs, and power consumption is reduced to the extent of 1W in standby mode. From the above results, we know that efficiency of proposed IC is superior to the previous IC.

• Korean Journal of Remote Sensing
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• v.38 no.3
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• pp.251-263
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• 2022

This paper presents an idea of ScanSAR image formation. For image formation of ScanSAR that utilizes the burst mode for raw signal acquisition, most conventional single burst methods essentially require a step of azimuth stitching which contributes to radiometric and phase distortions to some extent. Time-domain cross correlation could replace SPECAN which is most popularly used for ScanSAR processing. The core idea of the proposed method is that it is possible to relieve the necessity of azimuth stitching by an extension of Doppler bandwidth of the reference function to the burst cycle period. Performance of the proposed method was evaluated by applying it to the raw signals acquired by a spaceborne SAR system, and results satisfied all image quality requirements including 3 dB width, peak-to-sidelobe ratio (PSLR), compression ratio,speckle noise, etc. Image quality of ScanSAR is inferior to that of Stripmap in all aspects. However, it is also possible to improve the quality of ScanSAR image competitive to that of Stripmap if focused on a certain parameter while reduced qualities of other parameters. Thus, it is necessary for a ScanSAR processor to offer a great degree of flexibility complying with different requirements for different applications and techniques.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.41 no.1
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• pp.1-8
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• 2009

Mountain Pine Beetle (MPB) attacked pine was evaluated for pulp quality, chemical and physical properties, and bleachability. Chemical analyses showed that the dehydroabietic acid and total acetone extractives content were higher in the year 3 (grey) attacked MPB chips and lower in the year 5 (grey) attacked MPB chips as compared to a typical SPF (spruce/pine/fir) reference. Lignin and carbohydrate content of the MPB wood chips were comparable to the SPF. Similarly, there was little difference in kappa number, pulp yield and liquor consumption between the 3 and 5 year MPB attacked wood. Likewise there was no significant difference in the resulting tear strength, burst, or tensile strength. There appeared to be an improved bleaching response in the MPB attacked pulp as compared to the SPF reference, but this was accompanied by a slightly lower bleached pulp yield and higher bleach filtrate COD and solids content.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.6
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• pp.38-45
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• 1997

Skin color reappearance problem in color processing system is necessary to transform a specific color sand improve color reappearance quality as a reference color. The skin color has been situated as an important memory color not only in our lives but also in color application systems such as TV. Thus, skin color reappearance problem is more important than other color processing problem. In this paper, we propose a skin color reappearance algorithm for color enhancement in TV which use phase detector to detect the skin colors at real-time from 3.58 MHz color burst signal and color signal, comparators to discriminate the types of skin color, and micom to reprodece standard skin colors for races.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.29 no.3
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• pp.229-235
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• 1993

In this paper, a method of ghost cancelling for the television signals using complex adaptive filter is studied. The sin(x)/x signal is used as the reference signal a complex adaptive filter. The ghost cancelling characteristics considering the delay time, the attenuation, and the phase difference of multipath waves are investigated using horizontal sync pulse and color burst signal in composite video waveform. The influences of phase difference in ghost cancelling are investigated and the performances between the real processing and the complex processing are compared by the computer simulation. It was found that influences in ghost by phase difference are remarkably reduced by the complex adaptive filtering.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.7
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• pp.1566-1573
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• 1997

In this paper, we propose a favorite color correction algorithm for color enhancement in color application system which represent preferred colors for viewer's demands. The proposed algorithm corrects skin color which is widely used as a reference color for color control of color application system, blue color which is directly related to tri-stimulus values, and green color which has higher visual sensitivity. In the proposed algorithm, the vaiation range of phase detector output voltage was minimized for the favorite color saturation changes, thus the favorite from the burst signal for the phase detector characteristic, thus the favorite color was easilty detected from the other color without overlapping of correctionranges.

• The Journal of the Acoustical Society of Korea
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• v.21 no.3
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• pp.323-329
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• 2002

This paper proposes a frame reliability weighting method to compensate for a time-selective noise that occurs at random positions of speech signal contaminating certain parts of the speech signal. Speech frames have different degrees of reliability and the reliability is proportional to SNR (signal-to noise ratio). While it is feasible to estimate frame Sl? by using the noise information from non-speech interval under a stationary noisy situation, it is difficult to obtain noise spectrum for a time-selective noise. Therefore, we used statistical models of clean speech for the estimation of the frame reliability. The proposed MFR (model-based frame reliability) approximates frame SNR values using filterbank energy vectors that are obtained by the inverse transformation of input MFCC (mal-frequency cepstral coefficient) vectors and mean vectors of a reference model. Experiments on various burnt noises revealed that the proposed method could represent the frame reliability effectively. We could improve the recognition performance by using MFR values as weighting factors at the likelihood calculation step.