• Proceedings of the KAIS Fall Conference
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• 2009.05a
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• pp.483-486
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• 2009

인터넷폰과 화상회의를 위해 개발되어진 G.723.1 음성부호화기는 5.3kbps ACELP와 6.3kbps MP-MLQ 이중 전송률로 구성된다. 본 논문에서는 CELP 계열 음성부호화기의 음질 개선을 위해 스펙트럼 누설을 최소화할 수 있는 가변 윈도우를 이용한 새로운 스펙트럼 분석 알고리즘을 제안한다. 제안한 알고리즘을 ACELP에 적용한 실험결과에서 스펙트럼 왜곡은 약 0.1dB 정도 감소하였고, 잔차 에너지는 7% 정도 감소하였으며 주관적 음질평가 결과는 0.3 정도 개선되었다.

• Journal of the Korean Applied Science and Technology
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• v.32 no.4
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• pp.718-723
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• 2015

For the fabrication of the Si negative electrode in Li-ion batteries (LIBs) containing the cross-linking polymer binder, in this work, the urethane acrylate (UA) oligomer was synthesized via a simple synthetic process. The cross-linked poly(urethane acrylate) (CPUA)/carbone black (CB)/Si composite (CPUA/CB/Si composite) was fabricated through reactions between their reactive vinyl segments in the UA oligomer. Interestingly, the CPUA/CB/Si composite showed better cycle performance than the poly(vinylidene fluoride) (PVdF)/CB/Si composite (PVdF/CB/Si composite) and the polyurethane (PU)/CB/Si composite (PU/CB/Si composite). The CPUA/CB/Si composite had the best lithiation of about $2586mAh\;g^{-1}$. The UA oligomer showed a good compatibility with the electrode materials and current collector after and before a curing process.

• Proceedings of the IEEK Conference
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• 2001.06d
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• pp.273-276
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• 2001

CELP 부호화기는 선형 예측 합성에 의한 분석 부호화의 원칙에 기본을 두고 있다. 그리고 음성 신호의 스펙트럼을 LPC 분석을 통해 부호화하는데 고정 윈도우를 사용하여 부호화한다. 그러나 음성신호는 화자의 발성속도에 따라 파형의 변화가 시간적으로 빠르게 변화하기도 하고, 반대로 유사한 파형이 일정시간 유지되기도 한다. 따라서 윈도우의 크기를 발성속도에 맞추어 분석한다면 보다 효율적인 부호화를 할 수 있다. 본 논문에서는 발성속도에 따라 전송률을 달리 적용하는 방법을 제안한다. 발성속도의 측정은 스펙트럼 변화도를 이용하여 측정하였고, 발성속도가 빠를 때는 프레임 크기를 줄여 시간적으로 빠르게 변화하는 신호에 적응적으로 분석하고 대신 파라미터 표현에 비트를 줄인다. 반대로 발성속도가 느릴 때는 프레임 크기를 키우고 파라미터 표현에 비트를 더 할당한다. 제안한 방법을 실험하기 위해 G.723.1 5.3kbps ACELP 부호화기를 이용하였다 음질의 열하 없이 평균 16.34% 전송률 감소효과를 얻을 수 있었다.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.466-469
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• 2002

Using intelligent information contained within the speech to identify the specific hidden data in the watermarked multimedia data is considered to be an efficient method to achieve the speech digital watermarking. This paper presents the performance comparison between various types of speech codec in order to determine an appropriate one to be used in digital watermarking applications. In the experiments, the speech signal encoded by four different types of speech codec, namely CELP, GSM, SBC and G.723.1codecs is embedded into a grayscale image, and theirs performance in term of speech recognition are compared. The method for embedding the speech signal into the host data is borrowed from a watermarking method based on the zerotrees of wavelet packet coefficients. To evaluate efficiency of the speech codec used in watermarking applications, the speech signal after being extracted from the attacked watermarked image will be played back to the listeners, and then be justified whether its content is intelligible or not.

• Childhood Kidney Diseases
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• v.4 no.1
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• pp.1-5
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• 2000

Purpose: The plcr of spot urine has been uised to predict the timed urine protein excretion. Although this method reduces errors caused by variations in urine volume, it is relatively thconvenient and expensive. Recently, a more rapid and less expensive screening method with specific gravity(SG) has been reported, and we have examined whether estimated-creatinine(Cr-est) with urine 5G could be used in place of urine creatinine to predict 24-hour collected urine protein excretion in children. Methods: We had retrospectively analyzed protein, creatinine and urine SG in randomized spot urine samples of 147 patients from March 1998 till June 1998 in Korea university Guro hospital and compared the urinary protein creatinine ratio(P/Cr) with the protein estimated-creatinine ratio(P/Cr-est). We compared the correlation of urinary creatinine vs-urine 5G with the timed urine pretein excretion. Results: 1) urine SG accurately estimated urine creatinine concentration (r=0.407, P<0.001, Cr=SG x 4485.82-4482.87). 2) P/Cr correlated with urine protein excretion measured in a 24-hour urine collection (r=0.771, P<0.001, 24-hour collected urine protein : 0.338 x (P/Cr) 4+667.885). 3) P/Cr-est correlated with a 24-hour collected urine protein (r=0.723, P<0.001, 24-hour collected urine protein =0.354 x (P/Cr-est)+726.044), Conclusions: These results suggest that P/Cr-est with urine SG could be useful method for screening proteinuria in children.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.7
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• pp.718-723
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• 2004

Crystal structure of $(Ba-{1-x}La_x)[Mg_\frac{1+x}{3}}Nb_\frac{{2-x}{3}}]O_3$ (BLMN) ceramics with 0\leq1x \geq was investigated using synchrotron X-ray powder diffraction (XRD) and high reso(B $a_{l-x}$L $a_{x}$)[M $g_{(1+x)}$3/N $b_{(2-x)/3}$］ $O_3$lution transmission electron microscopy (HRTEM). When the La content, x, is above 0.1, the 1:2 ordered hexagonal structure found in Ba($Mg_\frac{1}{3}Nb_\frac{2}{3}})O_3$(BMN) was transformed into 1:1 ordered cubic structure. The 1:1 ordered cubic structure was maintained up to x=0.7. When x exceeded 0.7, however, BLMN was transformed into 1:1 ordered structure which has cation displacement and in-phase and anti-phase tilt of octahedra.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.51-54
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• 2000

This paper describes the fixed-point DSP implementation of a CELP(code-excited linear prediction)-based speech coder. The effective realization methodologies to maximize the utilization of the DSP's architectural features, specifically Parallel movement and pipelining are also presented together with the implementation results targeted for the ITU-T standard G.723.1 using Motorola DSP56309. The operation of the implemented speech coder is verified using the test vectors offered by the standard as well as using the peripheral interface circuits designed for the coder's real-time operation.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.191-194
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• 2002

최근 음성 부호화기의 연구방향은 저전송률, 저복잡도와 더불어 가변전송률 음성부호화기에 대한 연구로 진행되고 있다. 지금까지 제안된 저전송률 음성부호화기로는 스펙트럼 모델링을 이용한 MBE 계열과 혼성부호화 방식의 CELP 계열이 있다. 그 중에서 가장 많은 연구가 이루어지고 있는 방식이 CELP 방식이다. 이 방식은 4.8kbps 내외의 전송율에서 양호한 음질을 얻을 수 있다. 본 논문에서는 평균자승오차값을 최소화하여 계산량을 줄이고 음질을 향상시킬 수 있는 새로운 알고리즘을 제안한다. 먼저 G.723.1 부호화기에서 인지가중필터를 거친 신호를 LSP를 이용하여 각 포만트의 위치를 검출하여 Pole점만 비교하여 Zero점의 영향을 최소화 하였고 평균자승오차값을 최소화 하여 문턱값에 가장 가까운 값을 대표 피치이득계수로 정하고 그때의 피치와 함께 부호화한다.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.E1
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• pp.45-48
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• 2006

Mass size distributions of atmospheric particles in Cheonan were determined using a high volume air sampler equipped with a 5-stage cascade impactor. Bimodal distributions that are typical for urban atmospheric particles were obtained. A MMD of the fine particle mode was $0.47{\pm}0.05{\mu}m$ with a GSD of $2.72{\pm}0.21$, and those of the coarse particles were $5.15{\pm}0.18{\mu}m\;and\;2.09{\pm}0.09$, respectively. The annual average concentrations of TSP, PM10, PM2.5, and PM1 were 74.1, 67.5, 54.2, and $42.3{\mu}g/m^3$, respectively. Although the daily PM10 concentrations were under the current National Standard, the daily PM2.5 concentrations frequently exceeded the US Standard even in non asian dust periods. The fractions of PM 10, PM2.5, and PM1 in TSP were $0.905{\pm}0.013,\;0.723{\pm}0.022,\;and\;0.572{\pm}0.029$, respectively, and fine mode particles occupied $57{\sim}72%$ of the total particle mass. The results indicate that fine particles were at the concerning level, and should be the target pollutant for the regional air quality strategy in Cheonan.

• Korean Journal of Poultry Science
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• v.48 no.3
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• pp.133-142
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• 2021

The purpose of this study was to investigate whether enzyme-hydrolyzed poultry by-product meal (EHPBM) is more effective as a protein source than poultry by-product meal (PBM) and soybean meal (SBM) for broiler chickens. A group of 300 one-day-old broiler chicks was randomly allocated to three treatments with five replicates (20 birds/replicate) for five weeks. The treatments consisted of basal diets containing 1) SBM, 2) PBM, and 3) EHPBM. The EHPBM-fed group (1,853 g±125.60) showed the highest final body weight (P<0.05) when compared to the PBM-fed group (1,723 g±76.81) and SBM-fed group (1,545 g±62.31). The feed conversion ratio of the EHPBM treatment group (1.740±0.104) was significantly higher (P<0.05) than those of the SBM (1.653±0.056) and PBM groups (1.674±0.072). It can be speculated that the increased feed intake in the EHPBM group led to higher body weight gain and FCR. There was no significant effect of treatments on internal organ weight except for the bursa of Fabricius. Blood biochemical characteristic analysis showed that aspartate aminotransferase and alkaline phosphatase levels were higher in the EHPBM and PBM groups (P<0.05), probably due to the strained liver caused by the rapid growth of birds. In conclusion, EHPBM may partly replace conventional dietary protein sources such as soybean meal or poultry by-product meal and can be used to improve the productivity of broilers.