• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.655-660
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• 2002

The purpose of this study is to analyze void ratio, coefficient of water permeability, and strength characteristics when silica fume and carbon fibers were added in order to improve the strength of porous concrete, and when recycled aggregates were used. Comparing with the case that recycled aggregate was not used, as the replacement ratio of recycled aggregate increased, the differences in void ratios and strength characteristics were decreased. In the case that silica fume was used, the content of 10% silica fume was most effective in improving strength. In the case that carbon fibers were used, the content of 3% carbon fiber were good to achieve the highest flexural strength, and Pan-derived CF was much better than pitch-derived CF in improving these effects.

• KCI Concrete Journal
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• v.14 no.4
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• pp.161-169
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• 2002

The mechanical properties of fiber reinforced porous concrete for use as a planting material were investigated in this study. Changes in physical and mechanical properties, subsequent to the addition of carbon fiber and silica fume, were studied. The effects of recycled aggregate were also evaluated. The applicability as planting work concrete material was also assessed. The results showed that there were no remarkable changes in the void and strength characteristics following the increase in proportion of recycled aggregate. Also, the mixture with 10% silica fume was found to be the most effective for strength enforcement. The highest flexural strength was obtained when the carbon fiber was added with $3\%$. It was also noticed that PAN-derived carbon fiber was superior to Pitch-derived ones in view of strength. The evaluation of its usage for vegetation showed that the growth of plants was directly affected by the existence of covering soil, in case of having the similar size of aggregate and void.

• Journal of the Korean Wood Science and Technology
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• v.19 no.2
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• pp.56-64
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• 1991

The destructed chips(Pinus rigida Mill) were sulfonated under different conditions and defiberated. The yields and strengths of pulp, fatty acid and resin acid in sulfonated chips were determined. The results of this work were as follows: 1) A sulfonation caused a yield reduction to 97.9~88.2% at single stage. and to 94.9~88.2% at two stage pretreatment. The pulp yields were rapidly draped with increasing cooking temperature from $130^{\circ}C$ to $150^{\circ}C$ 2) Pulp strengths were improved with iacreasing cooking temperature. A sulfonation with 5% $Na_2SO_3$/NaOH(8/2) at single stage and 2% NaOH-5% $Na_2SO_3$ at two stage were most effective and gave the best combination of strength properteis. 3) Fatty acid esters in chips were mostly consisted of palmitic and olleic acid. During a sulfonation the former increased extensively, and the latter was lost with increase of cooking times. The amount of pimaric type in the chips was relatively decreased by the pretreatnent and abietic-type increased. But the changes between two resin acid types were insignificant. 4) The effciency of pitch removal was dependant upon cooking liquor pH. To remove sufficiently the resinous substance, the chips must be sulfonated at over pH 12. Therefore, taking account of pitch removel, two stage sulfonation is considered suitable as reinforcement pulp for newsprint manufacture from pitch pine chips : 2% NaOH($60^{\circ}C$ 1 hr) at first stage and 5% $Na_2SO_3$ ($130^{\circ}C$, 1hr) at secund stage.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.7
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• pp.28-35
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• 2010

In the display industry, COG bonding method is being applied to production of LCD panels that are used for mobile phones and monitors, and is one of the mounting methods optimized to compete with the trend of ultra small, ultra thin and low cost of display. In COG bonding process, electrical characteristics such as contact resistance, insulation property, etc and mechanical characteristics such as bonding strength, etc depend on properties of conductive particles and epoxy resin along with ACF materials used for COG by manufacturers. As the properties of such materials have close relation to optimization of bonding conditions such as temperature, pressure, time, etc in COG bonding process, it is requested to carry out an in-depth study on characteristics of COG bonding, based on which development of bonding process equipment shall be processed. In this study were analyzed the characteristics of COG bonding process, performed the analysis and reliability evaluation on electrical and mechanical characteristics of COG bonding using ACF to find optimum bonding conditions for ACF, and performed the experiment on bonding characteristics regarding fine pitch to understand the affection on finer pitch in COG bonding. It was found that it is difficult to find optimum conditions because it is more difficult to perform alignment as the pitch becomes finer, but only if alignment has been made, it becomes similar to optimum conditions in general COG bonding regardless of pitch intervals.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.358-364
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• 2018

An isotropic pitch precursor for fabricating carbon fibres was prepared by co-carbonization of ethylene bottom oil(EBO) and polyvinyl chloride (PVC). Various pre-treatments of EBO and PVC, and a high heating rate of $3^{\circ}C/min$ with no holding time, were evaluated for their effects on the oxidative stabilization process and the mechanical stability of the resulting fibres. Our stabilization process enhanced the volatilization, oxidative reaction and decomposition properties of the precursor pitch, while the addition of PVC both decreased the onset time and accelerated the oxidative reaction. Aliphatic carbon groups played a critical role in stabilization. Microstructural characterization indicated that these were first oxidised to carbon-oxygen single bonds and then converted to carbon-oxygen double bonds. Due to the higher heating rate and lack of a holding step during processing,the resulting thermoplastic fibers did not completely convert to thermoset materials, allowing partially melted, adjacent fibres to fuse. Fiber surfaces were smooth and homogeneous. Of the various methods evaluated herein, carbon fibers derived from pressure-treated EBO and PVC exhibited the highest tensile strength. This work shows that enhancing the naphthenic component of a pitch precursor through the co-carbonization of pre-treated EBO with PVC improves the oxidative properties of the resulting carbon fibers.

• Korean Journal of Audiology
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• v.25 no.3
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• pp.131-137
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• 2021

Background and Objectives: The current study investigates pitch coding using frequency following response (FFR) among vocalists, violinists, and non-musicians for Indian Carnatic transition music stimuli and assesses whether their listening biographies strengthen their F0 neural encoding for these stimuli. Subjects and Methods: Three participant groups in the age range of 18-45 years were included in the study. The first group of participants consisted of 20 trained Carnatic vocalists, the second group consisted of 13 trained violinists, and the third group consisted of 22 non-musicians. The stimuli consisted of three Indian Carnatic raga notes (/S-R2-G3/), which was sung by a trained vocalist and played by a trained violinist. For the purposes of this study, the two transitions between the notes T1=/S-R2/ and T2=/R2-G3/ were analyzed, and FFRs were recorded binaurally at 80 dB SPL using neuroscan equipment. Results: Overall average responses of the participants were generated. To assess the participants' pitch tracking to the Carnatic music stimuli, stimulus to response correlation (CC), pitch strength (PS), and pitch error (PE) were measured. Results revealed that both the vocalists and violinists had better CC and PS values with lower PE values, as compared to non-musicians, for both vocal and violin T1 and T2 transition stimuli. Between the musician groups, the vocalists were found to perform superiorly to the violinists for both vocal and violin T1 and T2 transition stimuli. Conclusions: Listening biographies strengthened F0 neural coding, with respect to the vocalists for vocal stimulus at the brainstem level. The violinists, on the other hand, did not show such preference.

• Journal of Audiology & Otology
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• v.25 no.3
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• pp.131-137
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• 2021

Background and Objectives: The current study investigates pitch coding using frequency following response (FFR) among vocalists, violinists, and non-musicians for Indian Carnatic transition music stimuli and assesses whether their listening biographies strengthen their F0 neural encoding for these stimuli. Subjects and Methods: Three participant groups in the age range of 18-45 years were included in the study. The first group of participants consisted of 20 trained Carnatic vocalists, the second group consisted of 13 trained violinists, and the third group consisted of 22 non-musicians. The stimuli consisted of three Indian Carnatic raga notes (/S-R2-G3/), which was sung by a trained vocalist and played by a trained violinist. For the purposes of this study, the two transitions between the notes T1=/S-R2/ and T2=/R2-G3/ were analyzed, and FFRs were recorded binaurally at 80 dB SPL using neuroscan equipment. Results: Overall average responses of the participants were generated. To assess the participants' pitch tracking to the Carnatic music stimuli, stimulus to response correlation (CC), pitch strength (PS), and pitch error (PE) were measured. Results revealed that both the vocalists and violinists had better CC and PS values with lower PE values, as compared to non-musicians, for both vocal and violin T1 and T2 transition stimuli. Between the musician groups, the vocalists were found to perform superiorly to the violinists for both vocal and violin T1 and T2 transition stimuli. Conclusions: Listening biographies strengthened F0 neural coding, with respect to the vocalists for vocal stimulus at the brainstem level. The violinists, on the other hand, did not show such preference.

• Composites Research
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• v.29 no.5
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• pp.262-268
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• 2016

In this work, the pitch-based carbon paper (P-CP) was prepared by re-impregnating of binder pitches and PAN-based milled carbon fibers (MCF) at low temperature carbonization process. The influence of MCF content on physicochemical properties of MCF/P-CP was investigated. As a result, the tensile strength of MCF/P-CP was increased sharply from 10 wt.% to 20 wt.% of MCF. Also, the increase of MCF content led to the decrease of interfacial contact resistivity and the improvement of electrical and thermal conductivity of MCF/P-CP. These results were probably due to the increase of density of MCF/P-CP, resulting in the formation of electrically and thermally conductive paths of the carbon paper.

• Science of Emotion and Sensibility
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• v.13 no.1
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• pp.215-224
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• 2010

This paper is designed to investigate the attributes of sound and emotion resided in traditional Eastern thought by looking into acoustic theories such as Sunguarakron (聲有哀樂論) in Akgi(樂記), Sungmuaerakron(聲無哀樂論) of Haegang and Akhakgebum(樂學軌範), Chongiron(天機論) in Choson(朝鮮) dynasty. Six types of emotions, namely sadness, pleasure, happiness, anger, respect, and, affection (哀心, 樂心, 喜心, 怒心, 敬心, 愛心) which is related with sounds was closely reviewed through Akgi(樂記). Also attributes of sounds such as loudness, sharpness, pitch, roughness, fluctuation strength and pleasantness was corresponded with plain & complicated(單複), pitch, good & bad(善惡) slow & fast(舒疾), loud & quiet(猛靜) respectively. In addition to this, this paper is narrowed down that the basic ideas about sound and emotions of Choson(朝鮮) confucian scholar was based on theory of music and rhythm on Akgi(樂記). Furthermore, the relationship between expressed sound and emotions which was revealed in Chongiron(天機論) has been examined. Finally, various applied research and studies will be promoted through this study, because this study will provide foundation which supports sounds and emotions of Eastern.

• Smart Structures and Systems
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• v.17 no.4
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• pp.593-610
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• 2016

In this study, an innovative and smart glass fiber-reinforced polymer (GFRP) hybrid bar was developed for stronger durability of concrete structures. As comparing with the conventional GFRP bar, the smart GFRP Hybrid bar can promise to enhance the modulus of elasticity so that it makes the cracking reduced than the case when the conventional GFRP bar is used. Besides, the GFRP Hybrid bar can effectively resist the corrosion of conventional steel bar by the GFRP outer surface on the steel bar. In order to verify the bond performance of the GFRP hybrid bar for structural reinforcement, uniaxial pull-out test was conducted. The variables were the bar diameter and the number of strands and pitch of the fiber ribs. Tensile tests showed a excellent increase in the modulus of elasticity, 152.1 GPa, as compared to that of the pure GFRP bar (50 GPa). The stress-strain curve was bi-linear, so that the ductile performance could be obtained. For the bond test, the entire GFRP hybrid bar test specimens failed in concrete splitting due to higher shear strength resulting in concrete crushing as a function of bar deformation. Investigation revealed that an increase in the number of strands of fiber ribs enhanced the bond strength, and the pitch guaranteed the bond strength of 19.1 mm diameter hybrid bar with 15.9 mm diameter of core section of deformed steel the ACI 440 1R-15 equation is regarded as more suitable for predicting the bond strength of GFRP hybrid bars, whereas the CSA S806-12 prediction is considered too conservative and is largely influenced by the bar diameter. For further study, various geometrical and material properties such as concrete cover, cross-sectional ratio, and surface treatment should be considered.