• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.833-836
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• 2001

본 논문에서는 한국어 음성인식 시스템의 성능 향상을 위해 청각 주파수 분해능을 가진 MEL-LPC Cepstrum을 음소단위의 HMM(Hidden Markov Model)을 기반으로 하는 인식 시스템에 적용하여 그 결과를 비교 검토하였다. 선형예측(LP) 분석 후에 후처리로서 주파수를 왜곡시킨 LPC-MEL 분석이 계산량이 적고 효과적이라 일반적으로 많이 사용되고 있으나 주파수 분해능은 많이 개선되지 않는다. 따라서 본 논문에서는 주파수 분해능을 개선하기 위해, 원 음성신호로부터 직접적으로 멜주파수로 왜곡시킨 후 선형 예측 분석을 수행하는 MEL-LPC 분석방법을 이용한 음소기반의 화자 독립 음성인식 시스템을 구성하여 기존의 LPC-MEL 분석방법과 비교실험을 통하여 MEL-LPC 분석방법의 유효성을 검토하였다. 실험에 사용한 음성 데이터베이스는 음소 및 단어 인식실험에서는 ETRI 445단어 DB, 연속 숫자음인식 실험에서는 KLE 4연속 숫자음 DB를 사용하였다. 화자 독립 음소인식 실험의 경우, 묵음을 제외한 47개의 유사 음소에 대하여 4상태 3출력의 Left-to-Right 모델을이용하였다. 단어 및 연속 숫자음 인식 실험의 경우, 유한상태 네트워크에 의한 OPDP법을 이용하였다. 화자 독립 음소, 단어 및 4연속 숫자음 인식 실험결과, 기존의 LPC-MEL Cepstrum을 사용한 경우보다 MEL-LPC Cepstum을 사용한 경우가 더 높은 인식률을 나타내어 한국어 음성인식 시스템에서 MEL-LPC 분석방법의 유효성을 확인할 수 있었다.

• Proceedings of the Acoustical Society of Korea Conference
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• 1994.06c
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• pp.403-406
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• 1994

음성은 화자의 상태 및 주변 환경에 따라 그 특징이 다양하게 변화한다. 본 논문에서는 음성신호의 특징 파라미터로 널리 쓰이고 있는 mel-cepstrum에 대해, 단어내에서의 변화를 정규화함으로써 인식성능을 향상시키고자 하였다. mel-cepstrum이란 단어 전체에 대한 mel-cepstrum의 평균 값으로 normalize 시킨 것이다. 한국어 숫자음에 대한 인식 실험결과, 본 논문에서 제안한 정규화된 mel-cepstrum이 정규화되지 않은 mel-cepstrum에 비해 우수한 인식 성능을 나타내었다. 또한 잡음 환경하에서 비교 실험한 결과에서도 상대적으로 우수한 인식률을 보였다.

• Journal of Veterinary Clinics
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• v.23 no.3
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• pp.230-235
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• 2006

This study was performed in rats to find the minimum dose of melatonin that can effectively prevent the formation of postoperative intraperitoneal adhesions. Forty-two Sprague Dawley male rats were divided into six groups consisting of 7 rats, respectively. After celiotomy, five abrasions of $0.5{\times}1cm$ area were made on the antimesenteric serosal surface of the colon with a scalpel blade. The abdominal cavity was filled with 1 ml of solution containing 1 mg/kg(Mel 1), 3 mg/kg(Mel 3), 10 mg/kg(Mel 10), 30 mg/kg(Mel 30) and 5% ethanol solution(sham) through the catheter, using a sterile syringe before abdominal closure. Control group was given no adjuvant. The locations and values of adhesion were assessed through the second operation on the 14th day after the first operation. The adhesions were located on serosa to mesentery(54 of 210, 25.7%), serosa to serosa(44 of 210, 21%), serosa to omentum (12 of 210, 5.7%) and serosa to parietal peritoneum(0 of 210, 0%). The incidences of adhesion in Control, Sham, Mel 1, Mel 3, Mel 10 and Mel 30 were 68.6%, 91.4%, 57.1%, 60.1%, 17.1% and 20%, respectively. The values of adhesion separation in Mel 10 and Mel 30 group were lower than those in other groups. However, there was no significant(p<0.05) between Mel 10 and Mel 30 group. This study showed that 10 mg/kg of melatonin were effective in reducing the intraperitoneal adhesion.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2499-2507
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• 2012

A novel and convenient electrochemical method has been developed for sensitive determination of melamine (MEL) using ascorbic acid (AA) as the recognition element. The working electrode employed in this method was modified with the nanocomposite of hydroxyapatite/carbon nanotubes to enhance the current signal of recognition element. The interaction between MEL and AA was investigated by fourier transform infrared spectroscopy and cyclic voltammetry, and the experimental results indicated that hydrogen bonding was formed between MEL and AA. Because of the existing hydrogen bonding and electrostatic interaction, the anodic peak current of AA was decreased obviously while the non-electroactive MEL added in. It illustrated that the MEL acted as an inhibitor to the oxidation of AA and the decreasing signals can be used to detect MEL. Under the optimal conditions, the decrease in anodic peak current of AA was proportional to the MEL concentrations ranging from 10 to 350 nM, with a detection limit of 1.5 nM. Finally this newly-proposed method was successfully employed to detect MEL in infant formula and milk, and good recovery was achieved.

• Development and Reproduction
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• v.27 no.3
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• pp.127-135
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• 2023

Effects of changes in photoperiod on the reproductive events in fish are suggested to be mediated mainly via the action of melatonin (MEL). Changing levels of plasma MEL throughout the day and year are suggested to influence the hypothalamus-pituitary-gonadal axis in fish. Therefore, in this study, we aimed to investigate the effects of MEL on oocyte maturation and germinal vesicle breakdown (GVBD) in the marine fish, Chaenogobius annularis, in vitro. Oocytes at three different stages (pre-, mid-, and late-vitellogenesis) were incubated with (a) only MEL (5, 10, 50, 100, 500, and 1,000 pg/mL) and (b) 50 pg/mL of 17α,20β-dihydroxy-4-pregnen-3-one (17α20βP), maturation-inducing hormone (MIH) of this species, and MEL (4-h incubation before addition of MIH). Any single MEL treatment did not significantly induce GVBD. However, treatment with 50 pg/mL MEL or MIH significantly induced GVBD. These results suggest that preincubation with MEL accelerates the effect of MIH on longchin goby oocyte maturation.

• Toxicological Research
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• v.30 no.2
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• pp.99-107
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• 2014

Melamine-induced nephrotoxicity is closely associated with crystal formation in the kidney caused by combined exposure to melamine (Mel) and cyanuric acid (CA). However, there are few dosage-finding studies for toxicological evaluation of chronic co-exposure to Mel and CA. The objective of this study was to investigate the possible mechanism by which a Mel and CA mixture lead to renal toxicity in rats. Mel and CA were co-administered to rats via oral gavage for 50 days. Nephrotoxicity was determined by measuring blood urea nitrogen (BUN) and serum creatinine (sCr) levels. Relative kidney weights were significantly increased in rats after co-exposure to Mel+CA (63/6.3 or 630/6.3 mg/kg) mixtures. BUN and sCr levels were significantly increased after Mel and CA co-exposure. Taken together, significant increase in KIM-1, NGAL, and calbindin levels were observed in the urine of rats exposed to Mel+CA (63/6.3 or 630/6.3 mg/kg) compared with the corresponding control group. Histological analysis revealed epithelial degeneration and necrotic cell death in the proximal tubules of the kidney after co-exposure to Mel+CA (63/6.3 or 630/6.3 mg/kg). Our data suggest that Mel-mediated renal toxicity may be influenced by CA concentrations in Mel-contaminated milk or foods.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.1
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• pp.333-342
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• 2012

This paper presents a vowel onset point (VOP) detection method based on the human auditory system. This method maps the "perceptual" frequency scale, i.e. Mel scale onto a linear acoustic frequency, and then establishes a series of Triangular Mel-weighted Filter Bank simulate the function of band pass filtering in human ear. This nonlinear critical-band filter bank helps greatly reduce the data dimensionality, and eliminate the effect of harmonic waves to make the formants more prominent in the nonlinear spaced Mel spectrum. The sum of mel spectrum peaks energy is extracted as feature for each frame, and the instinct at which the energy amplitude starts rising sharply is detected as VOP, by convolving with Gabor window. For the single-word database which contains 12 vowels articulated with different kinds of consonants, the experimental results showed a good average detection rate of 72.73%, higher than other vowel detection methods based on short-time energy and zero-crossing rate.

• Development and Reproduction
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• v.17 no.1
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• pp.45-53
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• 2013

The action of melatonin within the body of animals is known to be mediated by melatonin receptors. Three different types of melatonin receptors have been identified so far in fish. However, which of these are specifically involved in puberty onset is not known in fish. We cloned and analyzed the sequence of melatonin receptor 1a (mel 1a) gene in Nile tilapia Oreochromis niloticus. In addition, we examined the tissue distribution of gene expressions for three types of receptors, mel 1a, 1b and lc and investigated which of them is involved in the onset of puberty by comparing their expression with that of gonadotropin-releasing hormone receptor I (GnRHr I) gene using quantitative real-time PCR from 1 week post hatch (wph) to 24 wph. The mel 1a gene of Nile tilapia consisted of two exons and one bulky intron between them. Mel 1a gene was found to be highly conserved gene showing high homology with the corresponding genes from different teleost. All three types of melatonin receptor genes were expressed in the brain, eyes and ovary in common. Expression of mel 1a gene was the most abundant and ubiquitous among 3 receptors in the brain, liver, gill, ovary, muscle, eye, heart, intestine, spleen and kidney. Mel 1b and mel 1c genes were, however, expressed in fewer tissues at low level. During the development post hatch, expressions of both mel 1a and GnRHr I genes significantly increased at 13 wph which was close to the putative timing of puberty onset in this species. These results suggest that among three types of receptors mel 1a is most likely associated with the action of melatonin in the onset of puberty in Nile tilapia.

• Proceedings of the KAIS Fall Conference
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• 2009.05a
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• pp.768-771
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• 2009

현재 음성인식에서 가장 많이 사용하고 있는 특징벡터는 MFCC(Mel-Frequency Cepstral Coefficients)이다. 그러나 MFCC도 잡음이 존재하는 환경에서는 인식 성능이 저하된다. 이러한 MFCC의 단점을 해결하기 위해 mel sub-band 스펙트럼 차감법과 신호대잡음비에 따른 에너지 압축을 이용하는 CMSBS(Compression and Mel Sub-Band Spectral subtraction) 방법을 사용한다. 본 논문에서는 CMSBS 방법 적용 시 음성이 발성되는 구간과 묵음 구간에서 mel sub-band 스펙트럼 차감법이 동일한 조건으로 이루어져 발생하는 중요한 음성정보의 손실을 보완하기 위하여 신호의 주기성을 이용하여 spectral flooring 파라미터를 변형하는 방법을 제안한다. 제안한 방법으로 실험을 한 결과 잡음이 거의 없는 음성신호에 대해서는 기존의 방법과 비슷한 인식률을 가지고, 잡음성분이 많을수록 변형된 mel sub-band 스펙트럼 차감법을 적용한 방법이 인식률에서 보다 높은 성능 향상을 가져왔다.

• Journal of Physiology & Pathology in Korean Medicine
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• v.17 no.1
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• pp.209-212
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• 2003

A wide variety of cancer chemotherapeutic agents have been shown to induce programmed cell death (PCD, apoptosis) in various tumor cell fines in vitro. This study was performed to know how ginsenoside Rc affect on SK-MEL-28 cell line, and how they induce the apoptosis. SK-MEL-28 cell lines were treated with various concentrations of ginsenoside Rc and cultured for various times. At cell cycle analysis, cells arrested at G2/M phase by ginsenoside Rc and apotosis percentage increased along with increasing concentration and time. TUNEL assay was performed to know whether SK-MEL-28 cell fine die as apoptosis or necrosis by ginsenoside Rc. As a result, fluorescence increased along with increasing time and concentration. Fas expressed on SK-MEL-28 cell lines membrane by ginsenoside Rc was identified using flow cytometer. Ginsenoside Rc induced apoptosis against SK-MEL-28 cell fines, and the apoptosis mechanism was identified as Fas-mediated apotosis.