• ETRI Journal
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• v.28 no.3
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• pp.275-281
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• 2006

A very simple and efficient scheme for jitter reduction is proposed for a carrier frequency recovery loop using phase differential frequency estimation, which estimates the current frequency offset based on the difference of the average phases of two successive intervals. Analytical and numerical results presented in this paper show that by simply overlapping the observation intervals by half for frequency offset estimations, both the steady-state and transient performances can be improved. The proposed scheme does not require any additional hardware circuitry, but results in improved performance even with reduced complexity.

• Korean Journal of Organic Agriculture
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• v.25 no.3
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• pp.537-554
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• 2017

This study had purpose to examine the consumers preference and buying property of processed products by rice, barley, wheat, bean. For the study, the interview was conducted of 300 samples more than 19 years of age. We attempt to examine consumers' preference and individual properties when purchasing processed grain products. Questionnaire was filled for the 23 variable by referring to previous studies to investigate the properties to consider when consumer purchasing the products. To conceptualize, reduce the high correlation parameters by factor analysis. The results attribute to seven factors that safety, brand/image, taste/shelf life, convenience seeking, preferred high-quality, price, consumption patterns. These properties showed significant differences in demographics. First, there was statistically difference by age in safety, brand/image, high quality preference, taste/shelf life. Second, Safety and high-quality preference were the difference between jobs, and depending on household income were significant difference in consumption patterns. We analyzed the purchasing preference by purchase frequency. Ramen, bread, beer are higher purchase frequency than any processed grain products. On the other hand, frozen rice, soybean paste, red pepper paste that are used primarily domestic raw, were lower purchase frequency. But the difference of purchase property according to products was very similar that the highest factor is price, the following factor as taste. Based on these findings, the implications and the limitations of the study were presented.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.6
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• pp.788-798
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• 2017

Antarctic krill Euphausia superba are important components of the Antarctic marine ecosystem both economically and ecologically; to manage this species effectively, their distribution and abundance must be understood. Using the Kwang Ja-Ho (3,012 tonnage), a commercial fishing vessel, we conducted acoustic surveys during April 13-24, 2016, to estimate the distribution and population size of krill around the South Shetland Islands of the Antarctic Continent, We used acoustic techniques based on the dB-difference, a method used mainly to classify of marine species. We found that Antarctic krill were present in numbers over 99% at six survey stations, with the exception of Station 3, where we only found Electrona carlsbergi. There was no difference in cell size due to frequency differences, but echo signals differed between species: 4.7-12.0 dB for Antarctic krill, and -4.1~0 dB for Electrona carlsbergi.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.3
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• pp.305-312
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• 2018

This study was carried out to investigate euphausiid abundance in an acoustic survey from March 2010 to July 2010 to suggest reasonable usage and management of the euphausiid Euphausia pacifica in the coastal area of Guryongpo Pohang. The acoustic data were analyzed by the 2-frequency difference method and the distorted wave born approximation acoustical theoretical model, which is used for organisms of weak target strength with small scatter, such as euphausiid scatter, among other marine organisms. The distribution and monthly density of euphausiids were estimated in the survey area. The results show that the volume back scattering strength frequency difference for euphausiid was 13.91-7.6 dB, and their monthly averag density was $28.2g/m^2$.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2C
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• pp.226-233
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• 2009

A novel frequency offset estimation scheme using a periodogram is proposed for orthogonal frequency division multiplexing (OfDM) systems. A conventional scheme proposed by Ren has a problem that the fractional and residual frequency offset estimation steps do not compensate for the difference between the real frequency offset and estimated integer frequency offset in the noise channel. So, the frequency offset estimation performance of Ren's scheme is degraded. In this paper, a frequency offset estimation scheme is proposed, which has a larger estimation range than that of the factional and residual frequency offset estimation steps in Ren's scheme. The proposed scheme can compensate for the difference between the real frequency offset and estimated integer frequency offset, unlike Ren's scheme. From the simulation results, we can observe that the performance of the proposed scheme is better than that of Ren's scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.10
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• pp.1179-1182
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• 2016

In this paper, a new method to reduce the size of ROM in the direct digital frequency synthesizer (DDFS) is proposed. This method use the sine-linear phase difference method and differential PCM. The new ROM compression method can reduce the ROM size by using the two ROM. The quantized value of sine-linear phase difference is saved by the ROM1 of the $2^N$ sample period. The ROM2 save the difference between the original sine-linear phase difference value and the saved sample value of the ROM1. The ROM compression ratio of 37% is achieved by this method. Also, the power consumption is decreased according to the ROM size reduction.

• The Korean Journal of Food And Nutrition
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• v.30 no.4
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• pp.627-634
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• 2017

This study was performed to provide fundamental data on the dietary life according to the acculturation degree. The subject was 305 Chinese students in South Korea region. The questionnaire respondents are consisted of 148 male students (48.5%) and 157 female students (51.5%). There was a statistically significant difference in age, education level, residence time, and Korean language ability according to acculturation degree (p<0.05), but there was no statistically significant difference in gender, residence pattern, purpose of coming to Korea. There was a statistically significant difference between meals frequency, outside frequency, and the intake of Chinese food according to acculturation degree (p<0.05), but there was no significant difference in snake taking frequency (p>0.05). There was a statistically significant difference in drinks and computer time according to acculturation degree (p<0.05), but there was no statistically significant difference between smoking and exercise (p>0.05). The food intake style of Chinese students was 2.47 in noodles, 2.34 in lunches and 2.15 in breads. According to the acculturation degree, the food intake patterns showed statistically significant differences in dumping kind, congee, hamburger and pizza, while meat products, smoked meat, noodle, lunch, cereal, kimbap, sandwich. And there was no significant difference. The correlation between the factors influencing the acculturation degree of Chinese students showed a statistically significant effect on dietary habits, food intake, education level, residence period, and Korean language ability.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.271-274
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• 2001

In this paper, we propose a charge pump phase-locked loop (PLL) with multi-PFD which is composed of a sequential phase frequency detector(PFD) and a precharge PFD. When the Phase difference is within - $\pi$ ∼ $\pi$ , operation frequency can be increased by using precharge PFD. When the phase difference is larger than │ $\pi$ │, acquisition time can be shorten by the additional control circuit with increased charge pump current. Therefore a high frequency operation, a fast acquisition and an unlimited error detection range can be achieved.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.11
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• pp.521-528
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• 2003

A varactor diode was utilized in order to expand variable range of the natural oscillation frequency of an active phased-array antenna. We have conformed experimentally that the variable range of the natural oscillation frequency was expanded about three times in the oscillator controlled by the varactor diode. When frequency difference was given to the oscillators in the two elements antenna system, phase difference was appeared between the oscillators. The 2-, 3-, 5-elements patch antenna array was composed for the beam scanning experiments. All the above patch antennas showed good phased array characteristics. The experimental results are as follows that the scanning angle of the 2-elements array antenna is 28.6$^{\circ}$, the 3-elements array antenna is 29.4$^{\circ}$, and the 5-elements array antenna is 26.2$^{\circ}$.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1735-1740
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• 2000

The aim of this study is to analyze the sound insulation performance of windows depending on the sound source types and to propose the noise control method in the apartment house. The regions where apartment houses are constructed are varied in the dominant noise sources such as aircraft noise, railway noise and road traffic noise. For the experiment, nine noise sources including pink noise were selected and recorded, which was used in the experiment by reproducing. As a result of this study, the sound insulation performance of window was found that when the frequency contents of the noise were high level in all frequency bands the difference of sound insulation performance was negligible, but when the frequency contents were low level at particular frequency band the difference of sound insulation performance was shown very differently.