• Applied Chemistry for Engineering
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• v.32 no.5
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• pp.569-573
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• 2021

In this study, high-density carbon blocks were manufactured using coke, binder pitch, and impregnated pitch, then the effect of pitch fluidity on the densification of carbon blocks during the impregnation process was investigated. A green block was manufactured through high-pressure figuration of coke and binder pitch, and a carbon block was obtained through a heat treatment process. An impregnation process was performed to remove pores generated by volatilization of the binder pitch during the heat treatment process. The impregnation process was carried out the high-pressure reaction step of impregnating the pitch into the carbon block followed by the pretreatment step of melting the impregnation pitch. Melting of the impregnation pitch was carried out at 140~200 ℃, and the viscosity of the impregnation pitch decreased as the heat treatment temperature increased. The decrease in the viscosity of the impregnation pitch improved the fluidity and effectively impregnated the pores inside the carbon block, reducing the porosity of the carbon block by 83% and increasing the apparent density by 5%.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.611-614
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• 2005

It is well known that tire tread pattern has much influence on the tire pattern noise. The paper describes the method of pattern noise reduction by using the pitch sequence, both on the smooth asphalt roads and on the trenched concrete roads. The noise of tire is classified as either airborne or structure borne noise. Pattern noise through the airborne is considered as a major noise source at high speeds. As block impacting and air pumping by tread patterns are major noise source, tire pattern noise can be greatly influenced by optimal pitch sequence. The goal of this paper is to provide tire engineers with pitch sequence to reduce pattern noise effectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.8
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• pp.1587-1594
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• 1994

The pitch predictor is one of the most important part for the robust tree coder. The hybrid backward pitch adapation which is a combination of a block adaptation and a recursive adaptation is used for the pitch predictor. In order to improve the error performance and track the pitch period change of the input speech, it is proposed to smooth the input of the pitch predictor. The smoother with three taps can have fixed coefficients or variable coefficients depending on the estimated autocorrelation function of the output of the pitch synthesizer. The inclusion of a variable smoother can track the pitch period change within a block and reduce the effect of channel errors.

• Applied Chemistry for Engineering
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• v.29 no.6
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• pp.677-681
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• 2018

In this study, the carbon block was prepared using the fluorinated coke and binder pitch by molding compression to increase its density. After fluorination, it is confirmed that the fluorine element on the coke surface was introduced up to 24.14 at% using XPS analysis. The wettability between the fluorinated coke and binder pitch was evaluated according to the reaction temperature. From the result of contact-angle tests, it can be found that the wettability was improved up to 64.7% as more fluorine atoms were introduced on the surface of cokes. Also, the density of the carbon block with the highest amount of fluorine increased with 6.8% compared to that of using the carbon block prepared by the untreated cokes.

• Applied Chemistry for Engineering
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• v.34 no.6
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• pp.608-612
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• 2023

Nano-diamond (ND) was added during the carbon block preparation process to increase the thermal conductivity of the carbon block. Added ND controlled the generated pore of carbon block due to the volatilization of the binder pitch during the carbonization process. The ND was added to the kneading process of coke and binder pitch, and carbon blocks were prepared by pressing and carbonization. As the amount of added ND increased, the ND ratio of the carbon block increased. The added ND made a pass-way for generated gas by volatilizing the binder pitch during the carbonization process, increasing the density of the carbon block and reducing the porosity. The thermal conductivity of the carbon block was improved by increased density, lowered porosity, and the high thermal conductivity of added ND.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.177-177
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• 2010

본 연구에서는 반도체용 Si wafer에 마스크 공정 및 slit etching 공정을 적용하여 목표인 30um 이하의 Probe unit을 개발하기 위해 Deep Si Etching(DRIE) 장비를 이용하여 식각 공정에 따른 특성을 평가하였다. 마스크는 Probe block 조립에 적합한 패턴으로 설계 하였으며, slit의 에칭된 지점에 pin이 삽입될 수 있도록 그 폭을 최소한으로 설계하였다. 30um pitch와 20um pitch의 마스크를 각각 설계하여 포토공정에 의해 마스크패턴을 제작하였으며, 식각공정 결과 식각율 5um/min, profile angle $89^{\circ}{\pm}1^{\circ}$로 400um wafer의 양면관통 식각을 확인하였으며, 표면 및 단면 식각특성을 조사하였다.

• Journal of Korean Library and Information Science Society
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• v.39 no.3
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• pp.457-477
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• 2008

The purpose of this experimental study is to analyze the techniques of producing the traditional Korean ink sticks, in order to restore them. The major findings are as follows: (1) Korean traditional ink is a name which people generically calls a block of ink mass made from soots and pine pitch, and it can be classified into pine-pitch ink and oil-pitch ink according to the type of soot. (2) Pine-pitch ink is made from soot of burnt pine trees, and oil-pitch ink is made from soot of burnt plant, animal or mineral oil. Both are mixed with glue made from resin, and hardened into block form. (3) Raw materials of ink include soot, glue made from resin, and spices, and the techniques of making Korean traditional inks were documented in etc. (4) The techniques of making Korean traditional inks have not been handed down, but some craftsmen in modern Korea have restored those traditional techniques.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.575-577
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• 2009

Traditionally, tire made a role of function, which is supporting vehicle load, making brake, transferring, traction etc. So, there are a lot of studying for the tire. especially, tire noise is one of the most important parameter in the car noise. this thesis shows the method how to reduce the tire noise by using the optimal pitch sequence. Because the optimal pitch sequence prevents tire from generating the pure tone while driving the car on the ground.

• The Journal of the Acoustical Society of Korea
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• v.43 no.2
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• pp.207-213
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• 2024

In this paper, we study how to improve the performance of a machine learning-based automatic music transcription model by adding musical information to the input data. Where, the added musical information is information on the number of pitches that occur in each time frame, and which is obtained by counting the number of notes activated in the answer sheet. The obtained information on the number of pitches was used by concatenating it to the log mel-spectrogram, which is the input of the existing model. In this study, we use the automatic music transcription model included the four types of block predicting four types of musical information, we demonstrate that a simple method of adding pitch number information corresponding to the music information to be predicted by each block to the existing input was helpful in training the model. In order to evaluate the performance improvement proceed with an experiment using MIDI Aligned Piano Sounds (MAPS) data, as a result, when using all pitch number information, performance improvement was confirmed by 9.7 % in frame-based F1 score and 21.8 % in note-based F1 score including offset.

• The Journal of the Acoustical Society of Korea
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• v.19 no.2E
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• pp.8-13
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• 2000

In this paper, we present an adaptive formant tracking algorithm for speech using closed phase WRLS-VFF-VT method. The pitch synchronous closed phase methods is known to give more accurate estimates of the vocal tract parameters than the pitch asynchronous method. However the use of a pitch-synchronous closed phase analysis method has been limited due to difficulties associated with the task of accurately isolating the closed phase region in successive periods of speech. Therefore we have implemented the pitch synchronous closed phase WRLS-VFF-VT algorithm for speech analysis, especially for formant tracking. The proposed algorithm with the variable threshold(VT) can provide a superior performance in the boundary of phone and voiced/unvoiced sound. The proposed method is experimentally compared with the other method such as two channel CPC method by using synthetic waveform and real speech data. From the experimental results, we found that the block data processing techniques, such as the two-channel CPC, gave reasonable estimates of the formant/antiformant. However, the data windows used by these methods included the effects of the periodic excitation pulses, which affected the accuracy of the estimated formants. On the other hand the proposed WRLS-VFF-VT method, which eliminated the influence of the pulse excitation by using an input estimation as part of the algorithm, gave very accurate formant/bandwidth estimates and good spectral matching.