• Journal of Information Processing Systems
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• 제13권5호
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• pp.1213-1228
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• 2017

The pitch tracking of music has been researched for several decades. Several possible improvements are available for creating a good t-distribution, using the instantaneous robust algorithm for pitch tracking framework to perfectly detect pitch. This article shows how to detect the pitch of music utilizing an improved detection method which applies a statistical method; this approach uses a pitch track, or a sequence of frequency bin numbers. This sequence is used to create an index that offers useful features for comparing similar songs. The pitch frequency spectrum is extracted using a modified instantaneous robust algorithm for pitch tracking (IRAPT) as a base combined with the statistical method. The pitch detection algorithm was implemented, and the percentage of performance matching in Thai classical music was assessed in order to test the accuracy of the algorithm. We used the longest common subsequence to compare the similarities in pitch sequence alignments in the music. The experimental results of this research show that the accuracy of retrieval of Thai classical music using the t-distribution of instantaneous robust algorithm for pitch tracking (t-IRAPT) is 99.01%, and is in the top five ranking, with the shortest query sample being five seconds long.

• Carbon letters
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• 제4권2호
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• pp.79-85
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• 2003

MCMB (mesocarbon microbeads) has been synthesized from coal tar pitch, petroleum pitch and polymer compound generally. But yield of MCMB was low about 20~40 wt% and was not above 50 wt%. Neither MCMB was replaced with natural graphite because of economic performance, refining MCMB, and control of the particle size distribution. This study was performed to elevate yield of MCMB and to develop technique of particle size distribution. As the result, yield of MCMB that was synthesized from coal tar pitch increased more than 60 wt% about raw material and particle size of MCMB was restrained according to control of QI (quinoline insoluble) ingredient in raw pitch, heat treatment temperature and time.

• 말소리와 음성과학
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• 제6권1호
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• pp.21-30
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• 2014

This study aims to discuss pitch slope on Korean intonation curve in spontaneous speech data. For this study, 656 utterances were taken in the spoken corpus and used 'close-copy stylization'. And then the physical feature of pitch movements was extracted for the study. The pitch slope was calculated on the basis of time and pitch range in each utterance. As a result, the average and distribution of pitch slope is similar between men and women in the range of the pitch movement except for essential differences. The slope of pitch movement confirms that there are no differences between men and women. Pitch slope on a scale of -10 to 10 is 90% of the entire pitch slope; pitch slope that moves by time scale without curve is 33.1%; pitch slope that moves half of the pitch bandwidth during the average time for pitch movement is 23.4%; pitch slope that moves 100% of pitch bandwidth during a half of the average time for pitch movement is 10.4%. Those results imply the possibility of standardization methods of Korean intonation by pitch slope.

• 한국생산제조학회지
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• 제22권1호
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• pp.29-35
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• 2013

The pitch reducer consists of several planetary gearsets, and they should have good load distribution over gear tooth flank and load sharing among the planets to improve the durability. This work investigates how bearing internal clearances influence both the load distribution over the gear tooth flank and the planet load sharing. A whole system model is developed to analyze a pitch reducer. The model includes non-linear mesh stiffness of gears, non-linear stiffness of bearings. The results indicate that the face load factor and mesh load factor decrease, and the fatigue life of output shaft bearings increase as bearing internal clearances of output shaft decrease. Therefore, the internal clearance of output shaft bearing must be considered when designing the pitch reducer for wind turbines.

• Tribology and Lubricants
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• 제29권1호
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• pp.33-38
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• 2013

This study is aimed to predict the fatigue life for pitch bearings under combined radial, thrust load and moment. In order to do this, a series of simulation such as bearing load distribution, initial surface stress, subsurface stress and fatigue analysis is needd. Fatigue life for pitch bearing can be predicted by using a bearing's material fatigue property.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제44권2호
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• pp.59-65
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• 2018

Objectives: This study aimed to optimize the thread depth and pitch of a recently designed dental implant to provide uniform stress distribution by means of a response surface optimization method available in finite element (FE) software. The sensitivity of simulation to different mechanical parameters was also evaluated. Materials and Methods: A three-dimensional model of a tapered dental implant with micro-threads in the upper area and V-shaped threads in the rest of the body was modeled and analyzed using finite element analysis (FEA). An axial load of 100 N was applied to the top of the implants. The model was optimized for thread depth and pitch to determine the optimal stress distribution. In this analysis, micro-threads had 0.25 to 0.3 mm depth and 0.27 to 0.33 mm pitch, and V-shaped threads had 0.405 to 0.495 mm depth and 0.66 to 0.8 mm pitch. Results: The optimized depth and pitch were 0.307 and 0.286 mm for micro-threads and 0.405 and 0.808 mm for V-shaped threads, respectively. In this design, the most effective parameters on stress distribution were the depth and pitch of the micro-threads based on sensitivity analysis results. Conclusion: Based on the results of this study, the optimal implant design has micro-threads with 0.307 and 0.286 mm depth and pitch, respectively, in the upper area and V-shaped threads with 0.405 and 0.808 mm depth and pitch in the rest of the body. These results indicate that micro-thread parameters have a greater effect on stress and strain values.

• Carbon letters
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• 제25권
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• pp.78-83
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• 2018

Pyrolyzed fuel oil (PFO) and coal tar was blended in the feedstock to produce pitch via thermal reaction. The blended feedstock and produced pitch were characterized to investigate the effect of the blending ratio. In the feedstock analysis, coal tar exhibited a distinct distribution in its boiling point related to the number of aromatic rings and showed higher Conradson carbon residue and aromaticity values of 26.6% and 0.67%, respectively, compared with PFO. The pitch yield changed with the blending ratio, while the softening point of the produced pitch was determined by the PFO ratio in the blends. On the other hand, the carbon yield increased with increasing coal tar ratio in the blends. This phenomenon indicated that the formation of aliphatic bridges in PFO may occur during the thermal reaction, resulting in an increased softening point. In addition, it was confirmed that the molecular weight distribution of the produced pitch was associated with the predominant feedstock in the blend.

• 한국기계연구소 소보
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• 통권15호
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• pp.37-46
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• 1985

Properties of Precursor pitch derived from petroleum residue were studied physical and chemical analysis method for investigation of production of pitch fiber. For preparing of those precursor pitches it was carried out a temperature and time variation experiment i reactor. It was demonstrated the precursor pitch prepared in this study to have a similar properties to Ashland precursor pitch capable of bulk mesophase formation from the results of the basic analysis, that is, molecular weight distribution, coking yield, carbon content, chemical composition, etc.

• The Korean Journal of Ecology
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• 제17권3호
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• pp.261-275
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• 1994

수도권과 그 주변의 33장소의 리기다소나무 숲에서 연륜생장과 잔뿌리의 수직분포를 조사하였다. 생리적 연령이 16년과 20년 사이의 연륜의 생장은 전원지보다 도심지에서 불량하였다. 그리고 최근 5년간 (1985~1989)의 연륜생장은 연령 11년~20년, 연령 21년~30년 및 연령 31년~40년 그룹 모두에서 도심지에서 거리가 멀어짐에 따라 양호하였다. 리기다소나무 잔뿌리의 양은 도심지, 주변지 및 전원지 모두에서 토양의 깊이가 깊어짐에 따라 지수함수적으로 감소하였고, 그 양은 전원지에 비해 도심지에서 매우 적었다. 그리고 전원지의 잔뿌리의 수직분포와 비교해 볼 때, 도심지에서 잔뿌리는 토양층보다 낙엽층에 많이 분포하였다. 그리고 낙엽층 속의 잔뿌리 양과는 유의한 음의 상관이 있었다. 이들 결과로부터 도심지에서 리기다소나무 생장감소는 잔뿌리 생장감소와 잔뿌리의 비정상적인 수직분포에 원인이 있는 것으로 판단되었다.

• 풍력에너지저널
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• 제13권4호
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• pp.90-97
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• 2022

In this paper, a study on the vibration characteristics of the pitch gearbox of 8 MW large capacity wind turbines was conducted. The vibration analysis method of the pitch gearbox was proposed by combining the planetary gear train vibration model with the housing and carrier finite element model using the substructural synthesis method. We modeled the vibration excitation source for mass unbalance, gear mesh frequency, and bearing defect error action on the pitch gearbox, and performed a critical speed analysis. As a result of analyzing the critical speed of the pitch gearbox, the critical speed for the excitation source did not occur within the operation speed (84.87 rpm). In addition, as a result of applying 10 %, 20 %, …, 100 % of the largest load duration distribution (LDD) load, it was found that the bearing stiffness and the primary natural frequency were larger as the LDD load was larger. The primary natural frequency was 81.47 Hz for the lowest load among LDD data, which exceeded an operating speed of 84.87 rpm (5.09 Hz), so it was found that vibration caused by the change of LDD load did not occur in the operating speed range.