• Carbon letters
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• v.16 no.3
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• pp.171-182
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• 2015

Mesophase pitch is an important starting material for making a wide spectrum of industrial and advanced carbon products. It is produced by pyrolysis of petroleum residues. In this work, mesophase formation behavior in petroleum residues was studied to prepare environmentally-benign mesophase pitches, and the composition of petroleum residues and its influence on the mesophase formation was investigated. Two petroleum residues, i.e., clarified oil s (CLO-1, CLO-2) obtained from fluid catalytic cracking units of different Indian petroleum refineries, were taken as feed stocks. A third petroleum residue, aromatic extract (AE), was produced by extraction of one of the CLO-1 by using N-methyl pyrrolidone solvent. These petroleum residues were thermally treated at 380℃ to examine their mesophase formation behavior. Mesophase pitches produced as a result of thermal treatment were characterized physico-chemically, as well as by instrumental techniques such as Fourier-transform infrared spectroscopy, nuclear magnetic resonance, X-ray diffraction and thermogravimetry/derivative thermogravimetry. Thermal treatment of these petroleum residues led to formation of a liquid-crystalline phase (mesophase). The mesophase formation behavior in the petroleum residues was analyzed by optical microscopy. Mesophase pitch prepared from CLO-2 exhibited the highest mesophase content (53 vol%) as compared to other mesophase pitches prepared from CLO-1 and AE.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.15 no.1
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• pp.47-51
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• 2004

Normally, as a result of increased laryngeal growth, the male voice drops about one octave in pitch level during adolescence. Failure of the voice to drop in pitch is consider to be a clinically significant voice disorder - 'mutational dysphonia'. The aim of this article is to evaluate the changes brought about by voice therapy, using the analysis of the EGG measure from Lx Speech Studio program(Laryngograph Ltd, UK) as well as acoustic, and aerodynamic studies in 18-year-old mutational dysphonia patient. The results from the Lx Speech Studio program demonstrated bimodal distribution of DFx(Hz), DQx(%), QxFx and diplophonic characteristic. After voice therapy combined with manual compression method, the distribution of DFx, DQx, QxFx was changed uniform with a dramatic reduction of higher pitch level. In addition, this finding suggests the EGG measure helps to choice treatment options, monitor the efficacy of therapy, and estimate the prognosis of diseases.

• Journal of the Korean Society for Heat Treatment
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• v.34 no.3
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• pp.130-136
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• 2021

With the development of the industry, bearings that require higher durability and efficiency are required, and various methods to reduce friction and wear of bearings are being studied. In this study, a wear test was conducted for STB2, a bearing steel material, by machining a micro-line pattern on the race surface of the bearing by machining. The pattern pitch of the specimens was processed to 40㎛, 80㎛, and 150㎛, and the coefficient of friction characteristics were investigated for the unpatterned specimen and the specimen with a DLC thin film deposited on the surface. As a result of the wear test, the pattern pitch showed the smallest coefficient of friction at 40㎛, and it was confirmed that the smaller the pattern pitch, the better the tribology characteristics.

• Carbon letters
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• v.16 no.3
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• pp.215-218
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• 2015

Carbon micro particles with dimple patterns were produced by electro-spraying a solution of pitch in tetrahydrofuran. Particle formation depended on separation in an electrical field and volatilization of the solvent. More than 80% of the obtained carbon exhibited an average particle size of less than 50 μm. X-ray diffraction analysis suggests that the carbon with dimple patterns has increased crystallinity after heat treatment.

• Progress in Medical Physics
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• v.24 no.1
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• pp.54-60
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• 2013

The aim of this study was to analysis of the pitch and yaw deviations with or without using an aid-pillow for the head and neck cancer on the TomoTherapy. A total of 14 head and neck patients were selected to without-group (n=7) and with-group (n=7). A total of 333 MVCT image sets used to evaluate the translational (lateral, longitudinal and vertical) and rotational adjustments (pitch, roll and yaw) with 153 and 180 MVCT image sets at without- and with-group, respectively. Deviations of without- and with-groups were $0.12^{\circ}$ and $0.09^{\circ}$, respectively at pitch. And, deviations without- and with-groups were $0.47^{\circ}$ and $0.17^{\circ}$, respectively at yaw. In generally, with-group had reduced than without-group for the pitch and yaw deviations. Therefore, using an aid-pillow, it will able to increase the reproducibility of treatment for the head and neck cancer patients on the TomoTherapy.

• The Journal of Korean Society for Radiation Therapy
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• v.26 no.2
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• pp.239-245
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• 2014

Purpose : The purpose of this study is to verify the accuracy of dose delivery according to the pitch and roll rotational setup error with 6D robotic couch in Intensity Modulated Radiation Therapy (IMRT) for pelvic region in patients. Materials and Methods : Trilogy(Varian, USA) and 6D robotic couch(ProturaTM 1.4, CIVCO, USA) were used to measure and analyze the rotational setup error of 14 patients (157 setup cases) for pelvic region. The total 157 Images(CBCT 78, Radiography 79) were used to calculate the mean value and the incidence of pitch and roll rotational setup error with Microsoft Office Excel 2007. The measured data (3 mm, 3%) at the reference angle ($0^{\circ}$) without couch rotation of pitch and roll direction was compared to the others at different pitch and roll angles ($1^{\circ}$, $1.5^{\circ}$, $2^{\circ}$, $2.5^{\circ}$) to verify the accuracy of dose delivery by using 2D array ionization chamber (I'mRT Matrixx, IBA Dosimetry, Germany) and MultiCube Phantom(IBA Dosimetry, Germany). Result from the data, gamma index was evaluated. Results : The mean values of pitch and roll rotational setup error were $0.9^{\circ}{\pm}0.7$, $0.5^{\circ}{\pm}0.6$. The maximum values of them were $2.8^{\circ}$, $2.0^{\circ}$. All of the minimum values were zero. The mean values of gamma pass rate at four different pitch angles ($1^{\circ}$, $1.5^{\circ}$, $2^{\circ}$, $2.5^{\circ}$) were 97.75%, 96.65%, 94.38% and 90.91%. The mean values of gamma pass rate at four different roll angles ($1^{\circ}$, $1.5^{\circ}$, $2^{\circ}$, $2.5^{\circ}$) were 93.68%, 93.05%, 87.77% and 84.96%. when the same angles ($1^{\circ}$, $1.5^{\circ}$, $2^{\circ}$) of pitch and roll were applied simultaneously, The mean values of each angle were 94.90%, 92.37% and 87.88%, respectively. Conclusion : As a result of this study, it was able to recognize that the accuracy of dose delivered is lowered gradually as pitch and roll increases. In order to increase the accuracy of delivered dose, therefore, it is recommended to perform IGRT or correct patient's position in the pitch and roll direction, to improve the quality of treatment.

• Carbon letters
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• v.8 no.4
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• pp.335-339
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• 2007

Carbon/silicon composites were synthesized by mixing silicon powders with petroleum pitch and subsequent heat-treatment. The resultant composites were composed of carbon and nano-size crystalline silicon identified by XRD and EDX. FIB images and SEM images were taken respectively to detect the existence of silicon impregnated in carbon and the distribution of silicon on the carbon surface. The obtained carbon/silicon materials were assembled as half cell anodes for lithium ion secondary battery and their electrochemical properties were tested. The pitch/silicon composite (3 : 1 wt. ratio) heat treated at $1000^{\circ}C$ and mixed with 55.5 wt.% of graphite showed relatively good electrochemical properties such as the initial efficiency of 78%, the initial discharge capacity of 605 mAh/g, and the discharge capacity of 500 mAh/g after 20 cycles.

• Carbon letters
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• v.5 no.2
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• pp.62-67
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• 2004

Performance of carbon-carbon composites is known to be influenced by the fibre matrix interactions. The present investigation was undertaken to ascertain the development of microstructure in such composites when carbon fibres possessing different surface energies (T-300, HM-35, P120 and Dialed 1370) and pitch matrices with different characteristics (Coal tar pitch $SP110^{\circ}C$ and mesophase pitch $SP285^{\circ}C$) are used as precursor materials. These composites were subjected to two different heat treatment temperatures of $1000^{\circ}C$ and $2600^{\circ}C$. Quite interesting changes in the crystalline parameters as well as the matrix microstructure are observed and attempt has been made to correlate these observations with the fibre matrix interactions.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.3
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• pp.66-73
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• 2005

This study was performed to understand the changes in wood extractives, mainly acetone extracts, in pine woods (Pinus densiflora and Pinus rigida) treated by three blue stain fungi (BSF) such as native BSF in Korea, Leptographium sp., screened Albino strain(BSFcs-1) and commercial Cartapip and fungicide, Wood guard. In addition their pulping and bleaching properties were investigated. BSF treatment has significantly reduced acetone extracts, $25.1{\sim}30.4%$ decreasing in red pine and $22.9{\sim}28.1%$ in pitch pine. Three week aging treatment showed about 20% decreasing in red pine and 19.3% in pitch pine. There were not so significant differences in extracts reduction among native BSF and Albino-type strains (Albino strain, BSFcs-1, and commercial Cartapip). But fungicide, Wood guard, treated wood showed relatively lower decreasing rates of extractives, 14% in red pine and 10.1% in pitch pine. Therefore it is understandable that the fungicide could protect the wood from blue stain fungi attack, but has no effect on its extractive reduction. Concerned to pulping properties of BSF and fungicide treated woods, red pine and pitch pine, optimum pulping condition was 20% active alkali, wood to liquor ratio 1 to 6, $170^{\circ}C$, and 2.5 hr. In the case of BSF woods, optimum pulping condition was same as the sound wood, $43.5{\sim}45%$ of pulp yields and $1.3{\sim}1.45%$ of rejects. Screened pulp yield of fungicide treated wood was lower than those of BSF treated woods. Rejects in pulps were higher in fungicide-treated wood than BSF treated woods. Bleaching pulp yields were ranged of 92 to 93.5%. BSF, Cartapip and fungicide treated woods resulted in lower brightness of $55{\sim}58%$, but Albino-type strain(BSFcs-1) $61.3{\sim}62.3%$, very similar to untreated one. Therefore bleaching chemicals could be saved in the processing of chemical pulping.

• Phonetics and Speech Sciences
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• v.3 no.2
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• pp.99-105
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• 2011

The treatment for patients with mutational dysphonia typically is useful with vegetative phonation, but has not yet been studied. This study attempts to identify the effect of $SKTCLP^{(R)}$ using throat clearing and laughing in patients with mutational dysphonia. The study, which was designed by the author, included 26 patients aged from 14 to 32 years (mean: 18.7 years) who had been diagnosed with mutational dysphonia between January 2007 and June 2010. Voice therapy for these patients included $SKTCLP^{(R)}$, ranging from two to seven sessions (mean: 3.8 sessions). Results were evaluated by videostroboscopy, perceptual evaluation of GRBAS scale, aerodynamic test, and acoustic analysis before and after therapy. Most patients could phonate with low pitch from the beginning and sustain with normal pitch sound in the last session. We had found that glottic gap reduced after therapy and anterior-posterior compression of superior laryngeal part at the first time, and these patients had complete closure of the glottis after treatment. The results of acoustic and aerodynamic measures after treatment indicated significant decreases in Fo, Jitter, Shimmer, SFF, and SPI, and increases in MPT, Psub, and vocal efficiency (p<.05). $SKTCLP^{(R)}$ may be a useful treatment method in managing mutational dysphonia. We can suggest this technique may be useful in improving the voice quality of other functional dysphonia having glottal chink or functional aphonia.