• Journal of Advanced Marine Engineering and Technology
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• v.41 no.1
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• pp.83-90
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• 2017

In this paper, a sound reception system using a phase difference of whistle signals is proposed and analyzed based on spectral analysis. The proposed system receives whistle signals from four microphones installed in four different directions with 90-degree intervals between them. The proposed algorithm detects the phase of each received signal based on spectral analysis and estimates the direction of the whistle signal by obtaining the phase difference between the received signals from two adjacent microphones. Furthermore, we theoretically analyze the phase difference between two adjacent received signals according to their arrival angles and implement the proposed system using a DSP chip. In addition, the operation of the proposed algorithm are verified using the implemented system in a laboratory environment. Experimental results show that the proposed scheme can well estimate the direction of the whistle signal.

• Journal of Advanced Navigation Technology
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• v.21 no.2
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• pp.163-170
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• 2017

MLAT which is an independent cooperative surveillance system is applied to increase the positon resoultin of secondary survelliance radar. MLAT uses the hyperboic or hyperboloid position mesurement algorithm. Central processing unit of MLAT calculates target position using time difference of arrival (TDOA) which can be solved from time of arrival (TOA) information of each receivers (at least 4 receivers). To increase position resolution of MLAT which use TDOA, TOA which is transfer time from tranmitter to receiver shold be calculated with precision time resolution in receiver. This paper explained the MLAT system briefly and explained ATD which is one of means of calcuating pulse position. ATD is applied to solve the deviation of pulse position due to different amplitude of signals in mulitiple receivers. In this paper, to analysis the performance of ATD, the simulation result of LAS and CDS was compared with the simulation result of basic threshold method.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.3
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• pp.447-454
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• 2010

This paper presents multiple fuzzy prediction systems based on an Interval type-2 TSK fuzzy Logic System so that the uncertainty and the hidden characteristics of nonlinear data can be reflected more effectively to improve prediction quality. In proposed method, multiple fuzzy systems are adopted to handle the nonlinear characteristics of data, and each of multiple system is constructed by using interval type-2 TSK fuzzy logic because it can deal with the uncertainty and the characteristics of data better than type-1 TSK fuzzy logic and other methods. For input of each system, the first-order difference transformation method are used because the difference data generated from it can provide more stable statistical information to each system than the original data. Finally, computer simulations are performed to show the effectiveness of the proposed method for two typical time series examples.

• The Journal of the Acoustical Society of Korea
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• v.32 no.4
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• pp.287-293
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• 2013

We present a parametric array signal generating system using $3{\times}16$ transducer array which is composed of multi-resonant frequency transducers of 20kHz and 32.5kHz. To drive transducer array, sixteen channel amplifier using LM1875 chips is designed and implemented, and the PXI system based on the LabView 8.6 for arbitrary signal generation and analysis is used. Using the proposed system, we measure sound pressure level and beam pattern of difference frequency and verify the nonlinear effect of difference frequency. The theoretical absorption range and the Rayleigh distance are 15.51m and 1.933m, respectively and we verify that sound pressure of difference frequency is accumulated and increased at the near-field shorter than the Rayleigh distance. We verify that the beam pattern of the measured difference frequency and the beam pattern obtained by the superposition of two primary frequencies are similar, and high directional parametric signal was generated.

• Journal of the Korean Society of Food Culture
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• v.20 no.5
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• pp.525-531
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• 2005

This study was carried out to establish the consumer-centric food labeling system by investigating usage state, importance evaluation, problems and satisfaction, etc. on the current food labeling system by consumer. For usage state of checking the food label, 50.2% of respondents were replied ‘mostly check the label’, and they were indicated a significant difference on ‘education level(p<.05)’, and in case of married respondents, most were relied 'absolutely check the label', For the reason to check the food label, 61.8% of respondents were replied 'to determine whether it is stable or not', and they were indicated a significant difference on age(p<.01), marital status(p<.01), and job(p<.01). For the item considered as important things on the label of the whole food, 49.8% of respondents were replied that 'expiration and manufacture date is important', and they were indicated a significant difference(p<.001) on age, marital status, job. For item considered as important things on the label of each food, it was indicated that they considered food company as important thing in case of snack, soft drink, edible oils, and noodles, and food company in case of ice cream, and expiration and manufacture date in case of milk product and meat product. For the problems on the current food labeling system, the clauses 'Poor marking on food additives and materials contents' and 'untrue marking of nutrition contents' were indicated a significant difference on age(p<0.05, p<0.001), and the clause 'untrue marking of nutrition contents' were indicated a significant difference on marital status(p<.01) and job(p<.01).

• The Korean Journal of Nuclear Medicine Technology
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• v.27 no.1
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• pp.62-65
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• 2023

Purpose The purpose of this study is to determine whether the glucose loading method (GLM) is useful in the differentiation of cerebral gliomas by comparing it with fasting images. Materials and Methods The patients were 70 people diagnosed with cerebral gliomas, and the equipment was Discovery 710 (GE Healthcare, MI, USA). All patients fasted for more than 6 hours, and fasting images and GLM were performed under the same imaging conditions, and the examination interval was 1 to 14 days. GLM administered 250 ㎖ of 10% glucose solution prior to radiopharmaceutical injection. SUVmax of cerebral glioma and SUVmean of cerebral cortex were measured and then compared and analyzed by tumor-to-normal brain cortex ratio (TNR). Statistical analysis confirmed the difference between the two images with an independent-sample t-test. Results The averages of GLM and fasting TNR were 1.26 and 1.09, respectively, which were 15.6% higher in GLM. In low-grade, the difference in TNR was insignificant at 4%, but in high-grade, 23%, GLM was high. There was a statistically significant difference between the two images (P=0.008), but there was no statistically significant difference in TNR in the low grade (P=0.473), and there was a very significant difference in the high grade (P=0.005). Conclusion GLM increased TNR for cerebral gliomas. In particular, it was found that the TNR increased more in the high grade. Therefore, GLM is considered to be useful for the differentiation of high-grade gliomas.

• Journal of Integrative Natural Science
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• v.9 no.2
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• pp.155-160
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• 2016

Applying image processing techniques to education, the face of the learner is photographed, and expression and movement are detected from video, and the system which estimates degree of concentration of the learner is developed. For one learner, the measuring system is designed in terms of estimating a degree of concentration from direction of line of learner's sight and condition of the eye. In case of multiple learners, it must need to measure each concentration level of all learners in the classroom. But it is inefficient because one camera per each learner is required. In this paper, position in the face region is estimated from video which photographs the learner in the class by the difference between frames within the motion direction. And the system which detects the face direction by the face part detection by template matching is proposed. From the result of the difference between frames in the first image of the video, frontal face detection by Viola-Jones method is performed. Also the direction of the motion which arose in the face region is estimated with the migration length and the face region is tracked. Then the face parts are detected to tracking. Finally, the direction of the face is estimated from the result of face tracking and face parts detection.

• Journal of KSNVE
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• v.11 no.3
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• pp.401-409
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• 2001

Passive type mufflers installed on every car haute inherent problem of lowering engine power and fuel efficiency caused by backpressure which is byproduct of complex internal structure. Recent improvements like installing a calve to change exhaust gas path depending on power requirement and rpm have only marginally improved performance. Tremendous amount of recent research works on active exhaust noise control have failed to commercialize because of numerous physical and economical reasons. In this paper, a unique seal-active muffler using difference of transmission paths is presented. In this system exhaust pipe is divided into two and joined again downstream. Exhaust noise is reduced by destructive interference when two-divided noise join again with transmission paths'difference which is half of the wavelength of a main noise frequency. One divided path has a sliding mechanism to change length thereby transmission path length difference is adjusted to entwine rpm change. The proposed system has minimal backpressure and does not need a secondary sound source like a speaker so it can overcome many problems of failed active noise control methods. We have verified proposed system's superior performance by simulation and comparison experiment with passive mufflers.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.625-628
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• 2007

We present an efficient and robust technique to estimate the velocity of moving targets from a single SAR image. In SAR images, azimuth image shift is a well known phenomenon, which is observed in moving targets having slant-range velocity. Most methods estimated the velocity of moving targets from the distance difference between the road and moving targets or between ship and the ship wake. However, the methods could not be always applied to moving targets because it is difficult to find the road and the ship wake. We adopted a method estimating the velocity of moving targets from azimuth differentials of range-compressed image. This method is based on an assumption that Doppler center frequency shift of moving target causes a phase difference in azimuth differential values. The phase difference is linearly distorted by Doppler rate due to the geometry of SAR image. The linear distortion is eliminated from phase removal procedure, and the constant phase difference is estimated. Finally, range velocity estimates for moving targets are retrieved. This technique is tested using an ENVISAT ASAR image in which several unknown ships are presented. The theoretical accuracy of this technique is discussed by SAR simulation. The advantages and disadvantages of this method over the conventional method are also discussed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.3
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• pp.218-223
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• 2012

This study is focused on the evaluation of thermal output of TABS (Thermally Activated Building System). The aim of this study is to evaluate TABS in terms of the temperature difference between heating medium supply temperature ($T_s$) and return temperature ($T_r$), thermal output and the surface temperature distribution according to the design flow rate and the design flow temperature. Through the transient heat transfer simulation using temperature calculation using Crank-Nicolson FDM using Physibel Voltra 6.0 W, the temperature difference between $T_s$ and ��$T_r$, thermal output and the surface temperature distribution of specific TABS was calculated and evaluated. The results show that specific thermal output and temperature difference at $60^{\circ}C$ of supply water temperature were about 162 $W/m^2$, $13.6^{\circ}C$ respectively.