• Korean Journal of Optics and Photonics
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• v.5 no.2
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• pp.326-332
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• 1994

Performance of soliton based long-haul optical communication system with in-line optical amplifier repeaters are evaluated numerically. To reduce the optical amplifier noise, the amplifier gain is increased and the post amplifier loss is included. By theoretical calculation with 1480 nm co propagating pump, 7 dB amplifier gain and operating the amplifier 1 dB in compression, the spontaneous emission factor can be reduced from 2.37 to 1.45 by increasing the pump power from 3.71 to 11.53 mW and increasing the post amplifier loss from 0 to 10 dB. Then, power penalty can be reduced from 4.09 to 1.20 dB for 8,000'km transmission and the maximum transmission distance is 14,890 km. ,890 km.

• Korean Journal of English Language and Linguistics
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• v.3 no.3
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• pp.427-452
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• 2003

Korean is famous for having all voiceless stop sounds. Korean does have voiced stops but they are considered to exist only as the allophones of word initial /p, t, k/. My experiment shows the English word initial stop sounds [b, d, g] and the Korean lax stop series /p, t, k/ in word initial position are similar in the range of voice onset time. If English word initial[b, d, g] sounds are posited as voiced, then Korean word initial /p, t, k/ should be classified as voiced also. Phonetically English /b, d, g/ phonemes and Korean /p, t, k/ phonemes are very similar except the word initial [p, t, k] are devoiced slightly more, but not significant enough to be classified as voiceless than English word initial [b, d, g]. If we posit /b, d, g/ as Korean phonemes, it explains why Korean /p, t, k/ series has the allophones [b, d, g] instead of fortis stops /p', t', k'/ in Korean even though /p', t', k'/ has less positive VOT value than /p, t, k/. If we posit /b, d, g/ as Korean phonemes, then it does not cause spelling or pronunciation confusion either when Koreans learn English or English speakers learn Korean.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.8
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• pp.1528-1535
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• 1994

In this paper, a filtered-X LMS algorithm by new error path identification method is proposed for active noise control system. The proposed algorithm identifies accurately the error path transfer function using three microphones and the control of error signal through double loop scheme with on-line. In the computer simulation using the sinusoidal and the practical duct noise, the proposed algorithm reduces noise level about 29.1dB and 10.4dB, respectively. We can observe the improvement of about 0.5dB and 2.5dB in noise level compared with that obtained using the filtered-X LMS algorithm of Eriksson model.

• Journal of environmental and Sanitary engineering
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• v.16 no.1
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• pp.18-26
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• 2001

The increase of economic growth has brought out the noise pollutions in city regions. To evaluate these problems, this study was investigated to assessment and analysis of noise pollutions at Cheongju area in winter and summer seasons. The noise levels were measured and analyzed at the general areas the 4 roadside areas (park, residential, commercial, and industrial area). As a result, following facts have been found. The equivalent sound levels(Leq) at general are in winter were 51.3∼78.2 dB(A) at the daytime and 41.1∼63.1 dB(A) at the nighttime And in summer there were 53.5∼77.3 dB(A) at the daytime and 41.9∼64.0 dB(A) at the nighttime, respectively. These values were higher than average value of Korea. At the roadside area, the values of Leq were 51.9∼72.8 dB(A) at the daytime, 44.3∼68.2 dB(a) at the nighttime in winter, and in summer there were 62.5∼73.1 dB(A) at the daytime and 50.4∼68.3 dB(A) at the nighttime, respectively. These values were lower than average value of Korea. The calculated traffic noise index(TNI) were 64.6∼93.6 at the daytime and 26.5∼106.6 at the nighttime in winter, In summer, there were 65.0∼90.7 at the daytime, and 32.3∼91.8 at the nighttime. The TNI values varied wide ranges at the nighttime according to traffic volumes.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.4
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• pp.309-313
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• 2000

A experiment was carried out to measure the auditory threshold of dusky spinefoot Siganus fuscescens(Houttuyn) in the coast of Cheju Island by heartbeat conditioning technique using pure tones coupled with a delayed electric shock in order to investigate the hearing ability to audible sound. The audible range of dusky spinefoot extended from 80Hz to 800Mhz with a peak sensitivity at 200Hz. The mean auditory threshold levels of dusky spinefuot were 102dB, 96dB, 92dB, 95dB, 105dB and 121dB respectively in the range of measurement frequencies, As the frequency became higher than 300Hz, the auditory threshold increased rapidly.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.2
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• pp.505-513
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• 1996

In this paper the dual-mode bandpass filters with a Chebyshev response are designed and manufactured at Ku-band as well as K-band. Manufactured filters are resonated by two independent orthogonal $TE_{113}$ circular-cavity modes and characterized by 4-pole Chebyshev function. One is operating at a center frequency of 12.5GHz with a bandwidth of 100MHz and the other, a center frequency of 19.25GHz with 120MHz, respectively. The measureed experimental results of a 12.5GHZ dual-mode filter ahve a 1.2dB intertion loss in the passband and 65dB out-of-rejection, and a 19.25GHz filter has a 1.55dB insertion loss and 70dB out-of-rejection. These experimantal results shoults show good agreements with the design specifications.

• Proceedings of the Korean Society of Computer Information Conference
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• 2010.07a
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• pp.203-207
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• 2010

In this paper, The design and implementation of Multi Channel Receiver is described in this paper. This Receiver system operates at X-band with processing received signal, more than 80[dB] dynamic range and wide-band signals at the same time. To process direct received signals, this system has the built-in Digital De-modulators which offer the minimum loss on the receiving signal pass and has high stability by adding Built-In Test (BIT). The performance of Multi Receiver is the following. The gain, noise figure, difference of amplitude and phase on the signal pass is respectively $14{\pm}2[dB]$, 19[dB], ${\pm}2[dB]$, and $10^{\circ}$ below.

• The Journal of the Korea institute of electronic communication sciences
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• v.4 no.2
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• pp.87-92
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• 2009

In this paper, we designed and fabricated the active amplification block for the integrated antenna module. The fabricated amplification module have a proper gain and low noise figure in the band of AM/FM band, T-DMB band and GPS band, and show good isolation performance for each band. Manufactured circuits satisfied the gain performance 7 dB in AM band, 11 dB in FM band, 10 dB in T-DMB, and 17 dB in GPS band. The integrated amplification block was realized by 35 mm*35 mm size, and was shown as the same sensitivity performance as compared with a conventional reference antennas.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.12
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• pp.1335-1342
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• 2010

This paper presents design and measurement result of S-band, $\bigcirc$ kW solid-state transmitter and receiver for active array radar system. Transmitter characteristics show 63 dB gain, 200 usec pulse width(max.), 10 % duty(max.) and 63 dB pulse to pulse stability. Receiver characteristics show 23 dB gain and 3.2 dB noise figure. Receiving mode for pulse network analyzer is used for pulse to pulse stability measurement. Measurement results satisfies all specification.

• The Journal of the Acoustical Society of Korea
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• v.38 no.6
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• pp.697-702
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• 2019

We propose a multi-band multi-scale DenseNet with dilated convolution that separates background music signals from broadcast content. Dilated convolution can learn the multi-scale context information represented by spectrogram. In computer simulation experiments, the proposed architecture is shown to improve Signal to Distortion Ratio (SDR) by 0.15 dB and 0.27 dB in 0dB and -10 dB Signal to Noise Ratio (SNR) environments, respectively.