• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.1
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• pp.97-103
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• 2018

In satellite communication, modulated beacon signal is spreaded by gold sequence and the modulated beacon is transmitted via linear phase modulation. Due to the difference in characteristics of the satellite and the receiver on the ground, frequency offset (FO) occurs. An existing modulated beacon receiver is a method of synchronizing the frequency of a modulated beacon signal using FFT(Fast Fourier Transform), which not only increases the delay and complexity in terms of system implementation but also has a separate circuit for compensating the phase difference due to FO and phase offset from FFT points. In order to overcome this problem, this paper proposes and analyzes a scheme for compensating and demodulating the coarse FO and phase offset at one time using the 2-phase shaped characteristics of the modulated beacon signal. Also, through the simulation, the modulation index suitable for the proposed method is analyzed and the appropriate cumulative number is also analyzed.

• Journal of Korean Biological Nursing Science
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• v.4 no.2
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• pp.5-18
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• 2002

Purpose: Women have been often underdiagnosed and undertreated when they have as high mortality as men of ischemic heart disease, such as angina. One of the reasons of women's under treatment is associated with either vague, non-traditional symptoms or longer delay in seeking professional help when they experience ischemic heart disease. This study was conducted to investigate the characteristics of women's anginal pain induced by the treadmill test and to explore the potential relationship(s) between anginal pain and other psycho-physiologic factors. Methods: Of 22 female patients referred to treadmill test, 7 with positive finding participated in this study. Anginal pain in the past was analyzed by Rose questionnaire, whereas anginal pain induced by the treadmill test was identified by McGill pain scale, visual analogue scale and present pain index. Results: Women expressed more heaviness than sharp pain, and complained splitting more often than subjects in previous study that included both men and women. Pain intensity by VAS $3.64{\pm}3.94$, Pain rating index was $5.14{\pm}7.29$, present pain index was $1.57{\pm}1.81$, duration of pain was $5.14{\pm}4.8$ min. Exercise intensity was $6.0{\pm}4.63$ METs, exercise duration was $364.29{\pm}141.39$ sec, ST change was -2.0mm and rate of perceived exertion was $16.29{\pm}2.06$. The relationships between pain intensity and pain duration, ST segment changes were significant. Correlation among pain measures was significant. Conclusion: Generalization of these pilot findings may be inappropriate, and therefore, further larger study is needed.

• International Journal of Control, Automation, and Systems
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• v.4 no.2
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• pp.165-171
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• 2006

This paper proposes a data fusion algorithm of nonlinear multi sensor dynamic systems of synchronous sampling based on filtering step by step. Firstly, the object state variable at the next time index can be predicted by the previous global information with the systems, then the predicted estimation can be updated in turn by use of the extended Kalman filter when all of the observations aiming at the target state variable arrive. Finally a fusion estimation of the object state variable is obtained based on the system global information. Synchronously, we formulate the new algorithm and compare its performances with those of the traditional nonlinear centralized and distributed data fusion algorithms by the indexes that include the computational complexity, data communicational burden, time delay and estimation accuracy, etc.. These compared results indicate that the performance from the new algorithm is superior to the performances from the two traditional nonlinear data fusion algorithms.

• Environmental Engineering Research
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• v.23 no.1
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• pp.107-113
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• 2018

Air quality and pollution have recently become a major concern; vehicle emissions significantly pollute the air, especially in large and crowded cities. There are various factors that affect vehicle emissions; this research aims to find the most influential factors affecting $CO_2$ and $NO_x$ emissions using Adaptive Neural Fuzzy Inference System (ANFIS) as well as a systematic approach. The modified ANFIS (MANFIS) was developed to enhance modelling and Root Mean Square Error was used to evaluate the model performance. The results show that percentages of $CO_2$ from trucks represent the best input combination to model. While for $NO_x$ modelling, the best pair combination is the vehicle delay and percentage of heavy trucks. However, the final MANFIS structure involves two inputs, three membership functions and nine rules. For $CO_2$ modelling the triangular membership function is the best, while for $NO_x$ the membership function is two-sided Gaussian.

• Journal of the Korean Society of Safety
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• v.30 no.4
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• pp.73-78
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• 2015

The autoignition temperatures(AIT) of solvent mixture is important index for the safe handling of flammable liquids which constitute the solvent mixtures. Therefore, the AITs of common pure chemical substances are widely reported, but very limited data are available for mixtures. This study, the toluene and 2-butnaol system which used mixture solution solvent was measured the AIT and ignition delay time by using ASTM E659 apparatus. The AITs of toluene and 2-butanol constituted binary system were $547^{\circ}C$ and $400^{\circ}C$, respectively. The experimental AIT of toluene and 2-butanol were a good agreement with the calculated AIT by the proposed equations with a few average absolute deviation(A.A.D.).

• The Journal of the Acoustical Society of Korea
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• v.18 no.1
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• pp.25-31
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• 1999

This paper proposes a new wide-band beamforming algorithm which has Gaussian weighting at nested linear array for acoustic measurement. The beamforming is performed one-shot by using all sensors simultaneously, not octave-by-octave. Gaussian weighting of frequency-dependent function is applied to each sensor before time-delay compensation so as to control the frequency receiving band of each sensor. As the results of the simulations, it is confirmed that the proposed algorithm can form the one-shot beams having uniform directivity index and also it can be applied to the broad-band acoustic measurement.

• Structural Monitoring and Maintenance
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• v.1 no.4
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• pp.411-425
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• 2014

A relatively low frequency Lamb wave-based damage identification method called damage imaging method for rectangular composite plate is presented. A damage index (DI) is generated from the delay matrix of the Lamb wave response signals, and it is used to indicate the location and approximate area of the damage. The viability of this method is demonstrated by analyzing the numerical and experimental Lamb wave response signals from rectangular composite plates. The technique only requires the response signals from the plate after damage, and it is capable of performing near real time damage identification. This study sheds some light on the application of Lamb wave-based damage detection algorithm for plate-type structures by using the relatively low frequency (e.g., in the neighborhood of 100 kHz, more suitable for the best capability of the existing fiber optic sensor interrogator system with the sampling frequency of 500 kHz) Lamb wave response and a reference-free damage detection technique.

• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.79-82
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• 1999

The right half plane (RHP) zeros may cause severe problems, such as undershoots, oscillations and time delay in the transient response of the systems. In this paper, we formulate a linear quadratic type problem to deal with the effects of the RHP zeros in the nonminimum phase systems. Based on the LQ formulation, this paper shows the trade-off relation between undershoot and rising time performances in nonminimum phase systems by using a new performance index which consists of new state and tracking error. And performances of the proposed method are shown via computer simulations.

• Journal of the Korean Society of Combustion
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• v.21 no.3
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• pp.16-23
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• 2016

In this study, skeletal mechanisms are produced by directed relation graph with specified threshold value and sensitivity analysis based on species database from the directed relation graph. Skeletal mechanism is optimized through the elimination of unimportant reaction steps by computational singular perturbation importance index. Reduction is performed for the detailed mechanism of methyl butanoate consisting of 264 species and 1219 elementary reactions. Validation shows acceptable agreement for auto-ignition delays in wide parametric ranges of pressure, temperature and equivalence ratio. Methyl butanoate has been proposed as a simple biodiesel surrogate although the alkyl chain consists of four carbon atoms. The resulting surrogate mechanism for n-heptane and MB consists of 76 species and 226 reaction steps including those for NOx.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.2
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• pp.202-209
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• 2001

As a part of stringent emission regulations, OBD on a converter is requested by EU and CARB. It demands that MIL is light-on to inform the failure to the driver when the converter is failed in its function. Usually dual oxygen sensor method is used for converter OBD. For this, detail methods, like amplitude ratio, time delay and frequency ratio methods are adapted for vehicle application. Actually, the cars produced later than MY94 for US market are using one of these methods. In this study, OSCs of converters are investigated with an absolute measuring method. The converters are aged with a furnace aging, an engine bench aging and vehicle aging method to represent various aging condition in field applications. An OBD index that is used for TLEVs regulation is also investigated to find a relation between two parameters. The relations of these parameters with THC emission on vehicle are evaluated.