Effect of low processing rate on homogeneous microstructural evolution of polyacrylonitrile‑based carbon fibers

Doo‑Won Kim,Dae Ho Kim,Sung Ryong Kim,Bo‑Hye Kim,Yun Hyuk Bang,Duck Joo Yang,Go Bong Choi,Yoong Ahm Kim,Kap Seung Yang 한국탄소학회 2019 Carbon Letters Vol.29 No.5

This study demonstrates that low processing rate for producing polyacrylonitrile (PAN)-based carbon fiber is a critical to obtain a homogeneous radial microstructure with high resistance to oxidation, thereby resulting in their improved mechanical strength. The dry-jet wet spun PAN organic fibers were processed (e.g., stabilized and then carbonized) utilizing two different rates; one is 1.6 times longer than the other. The effect of processing rate on the microstructural evolutions of carbon fibers was analyzed by scanning electron microscopy after slow etching in air, as well as Raman mapping after graphitization. The rapidly processed fiber exhibited the multilayered radial structure, which is caused by the radial direction stretching of the extrusion in the spinning. In case of the slowly processed fiber, the layered radial structure formed in the spinning process was changed into a more homogeneous radial microstructure. The slowly processed fibers showed higher oxidation resistance, higher mechanical properties, and higher crystallinity than the rapidly processed one. Raman mapping confirmed that the microstructure developed during spinning was sustained even though fiber was thermally treated up to 2800 °C.

An Improved Speech Processing Strategy for Cochlear Implants Based on an Active Nonlinear Filterbank Model of the Biological Cochlea

Kim $^$, Kyung Hwan,Choi, Sung Jin,Kim, Jin Ho,Kim, Doo Hee IEEE 2009 IEEE Transactions on Biomedical Engineering Vol.56 No.3

<P>The purpose of this study was to improve the speech processing strategy for cochlear implants (CIs) based on a nonlinear time-varying filter model of a biological cochlea. The level-dependent frequency response characteristic of the basilar membrane is known to produce robust formant representation and speech perception in noise. A dual resonance nonlinear (DRNL) model was adopted because it is simpler than other adaptive nonlinear models of the basilar membrane and can be readily incorporated into the CI speech processor. Spectral analysis showed that formant information is more saliently represented at the output of the proposed CI speech processor compared to the conventional strategy in noisy conditions. Acoustic simulation and hearing experiments showed that the DRNL-based nonlinear strategy improves speech performance in a speech-spectrum-shaped noise.</P>

예비체육교사의 패럴림픽에 대한 이해도 비교 연구

김상두(Sang Doo Kim),김준석(Jun Sik Kim) 한국사회체육학회 2014 한국사회체육학회지 Vol.0 No.57

The purpose of this study is to find out the level of understanding for pre-service physical-education teachers about the Paralympics and the differences between physical education majors and adapted physical education majors. For the purpose of the survey, a distinct difference between the groups on a survey has been identified. The survey material used for this study with a modification is based on Yeon-Sook Ko, Kyung-Sook Kim``s modified survey(2005) that scale analysis of disability attitude factor, which DFS(Disability Factor Scale) invented by Siller(1983) and translated by Jong-Nam Lee(1994), was used as a reference. For this study, collected 380 papers of information was updated and SPSS 18.0 program was used for its analysis with significant level of 5 percent or below. The frequency analysis has been conducted to figure out the subject``s general features, and t-test which is mean difference analysis and One-Way ANOVA have been conducted to see the awareness of the Paralympics. These tests were also used to verify differences between the two groups differentiated by major. The result are as followed. First, male have better understanding toward Paralympics than female do. However, none of statistical significance-difference was found. Second, the level of understanding toward Paralympics for all graders shows no sign of statistical significance-difference. Third, overall, adapted physical education majors have decent level of understanding toward Paralympics and the gap created from the fact, that whether he/she took adapted physical education classes, was shown. Fourth, a group with experience of volunteering turned out to have high level of understanding toward Paralympics and statistical significance-difference was found. It is shown that the differences about understanding toward Paralympics between the groups exist and pre-service physical-education teachers have lower level of understanding toward Paralympics compared to adapted physical-education majors. Fifth, the understanding level of pre-service physical-education teachers indicates areal gap and classes taken. In this study, a survey has been developed to find out the understanding level of Paralympics, which is one of the major events, for pre-service physical-education teachers and the differences between the groups have been identified. In this study which is to develop a survey as base line data to vitalize , it is suggested as followed. First, due to the fact that pre-service physical-education teachers were the subject for this study, an additionalstudy for a group of teachers who are currently working in the field should be made. Second, this study is only for major events of disabled for Paralympics. Later on, hence, study including morefeatures is a mandatory, such as various games, domestic sports festival for the people with handicapped. Third, due to this study is focused on pre-service physical education teacher, later, research which is forspecial education teacher should be needed for their better physical education service.

발성법(發聲法)의 이론(理論)과 실제(實際)

김상두 ( Sang Doo Kim ) 건국대학교 교육연구소 1980 교사와 교육(구 교육논집) Vol.5 No.-

Voice production should be based on scientific principle. The science of voice production is a knowledge of certain phenomena of physical movements which are found under certain conditions to occur regularly and which produce certain definite effects. There is only one way to sing perfectly and that is the correct scientific way. All singing must of necessity be beautiful, first, last and always. Rather have it said that the voice is small and beautiful than loud and otherwise. The small beautifully placed voice is capable of portraying the full gamut of human emotions. Therefore, it is necessary to develop our own instrument, which is the vocal apparatus we rely upon to produce our own beautiful singing. When singing is most scientifically produced, and the voice soars out smothly, evenly and vibrantly with its resultant seeming effortless singing. The great fundamental objectives or principles in voice production are, proper posture, breath control, free tone, balanced, efficient ringing sonorous tone, and expressive and varied tone color. Proper posture is a fundamental for control and maximum success in any type of skill activity whether it be athletics or musical performance. Necessary physical development for singing begin with habituation of proper posture and continuss through breath development and strengthening of the vocal organs through singing and tonal exercises. Efficient daphragmatic-costal breath control is the great fundamental in singing. Breath control, or breath support, means to keep tone flowing evenly, freely and firmly. Freedom vitality, expressive tone color, variety, efficiency, sonority, and evenness in tonal production is also fundamental principle in singing. The first reguisite in tonal technic is freedom of production. It is vital that we learn to both hear and feel the difference between good and bad tone and, eventually, between the finest shades of discrimination.

Factored MLLR Adaptation

Nam Soo Kim,June Sig Sung,Doo Hwa Hong IEEE 2011 IEEE signal processing letters Vol.18 No.2

<P>One of the most popular approaches to parameter adaptation in hidden Markov model (HMM) based systems is the maximum likelihood linear regression (MLLR) technique. In this letter, we extend MLLR to factored MLLR (FMLLR) in which the MLLR parameters depend on a continuous-valued control vector. Since it is practically impossible to estimate the MLLR parameters for each control vector separately, we propose a compact parametric form of the MLLR parameters. In the proposed approach, each MLLR parameter is represented as an inner product between a regression vector and transformed control vector. We present an algorithm to train the FMLLR parameters based on a general framework of the expectation-maximization (EM) algorithm. The proposed approach is applied to adapt the HMM parameters obtained from a database of reading-style speech to singing-style voices while treating the pitches and durations extracted from the musical notes as the control vectors. This enables to efficiently construct a singing voice synthesizer with only a small amount of singing data.</P>

Solar Cells: Amorphous Zinc Stannate (Zn₂SnO₄) Nanofibers Networks as Photoelectrodes for Organic Dye‐Sensitized Solar Cells (Adv. Funct. Mater. 25/2013)

Choi, Seung‐,Hoon,Hwang, Daesub,Kim, Dong‐,Young,Kervella, Yann,Maldivi, Pascale,Jang, Sung‐,Yeon,Demadrille, Renaud,Kim, Il‐,Doo WILEY‐VCH Verlag 2013 Advanced Functional Materials Vol.23 No.25

<P>Highly porous amorphous Zn<SUB>2</SUB>SnO<SUB>4</SUB> electrodes are prepared using electrospinning techniques and combined with organic or ruthenium dyes to fabricate dye‐sensitized solar cells. As reported by Sung‐Yeon Jang, Renaud Demadrille, Il‐Doo Kim, and co‐workers on page 3146, the devices based on 3‐μm‐thick electrodes and the organic dyes demonstrate significantly improved performances compared to those using the ruthenium complex. Using this approach, solar cells with power conversion efficiencies up to 3.7% are obtained. </P>

Innovative Nanosensor for Disease Diagnosis

Kim, Sang-Joon,Choi, Seon-Jin,Jang, Ji-Soo,Cho, Hee-Jin,Kim, Il-Doo American Chemical Society 2017 Accounts of chemical research Vol.50 No.7

<P>As a pioneering technique, a bioinspired templating route using apoferritin, that is, a hollow protein cage, has been proposed to obtain nanoscale (similar to 2 nm) catalyst particles with high dispersity. Nanocatalysts encapsulated by a protein shell were first used in chemiresistive type breath sensors for catalyst functionalization on 1D metal oxide structures. We discuss the robustness and versatility of the apoferrtin templating route for creating highly dispersive catalytic NPs including single components (Au, Pt, Pd, Rh, Ag, Ru, Cu, and La) and bimetallic catalysts (PtY and PtCo), as well as the core shell structure of Au Pd (Au-core@Pd-shell). The use of these catalysts is essential to establish high performance sensors arrays for the pattern recognition of biomarkers. In addition, novel multicomponent catalysts provide unprecedented sensitivity and selectivity. With this in mind, we discuss diverse synthetic routes for nanocatalysts using apoferritin and the formation of various catalyst-1D metal oxide composite nanostructures. Furthermore, we discuss detection capability of a simulated biomarker gas using the breath sensor arrays and principal component analysis. Finally, future prospects with the portable breath analysis platform are presented by demonstrating the potential feasibility of real-time and on-site breath analysis using chemiresistive sensors.</P>

Intranasal Delivery of HMGB1 siRNA Confers Target Gene Knockdown and Robust Neuroprotection in the Postischemic Brain

Kim, Il-Doo,Shin, Joo-Hyun,Kim, Seung-Woo,Choi, Sunghyun,Ahn, Junseong,Han, Pyung-Lim,Park, Jong-Sang,Lee, Ja-Kyeong Elsevier Science B.V., Amsterdam 2012 Molecular therapy Vol.20 No.4

COMPARISON OF UNDERWATER ELECTRICAL DISCHARGE PROCESSES FOR THE INACTIVATION OF Escherichia coli

Kim, Sang Don,Jang, Doo Il,Lim, Byung-Jin,Jang, Dong Lyong,Mok, Young Sun,Lee, Robert Sang Baek OAIMDD - EcoZone Publishing House 2014 Environmental engineering and management journal Vol.13 No.1

An injectable cationic hydrogel electrostatically interacted with BMP2 to enhance <i>in vivo</i> osteogenic differentiation of human turbinate mesenchymal stem cells

Kim, Mal Geum,Kang, Tae Woong,Park, Joon Yeong,Park, Seung Hun,Ji, Yun Bae,Ju, Hyeon Jin,Kwon, Doo Yeon,Kim, Young Sik,Kim, Sung Won,Lee, Bong,Choi, Hak Soo,Lee, Hai Bang,Kim, Jae Ho,Lee, Bun Yeoul,Mi Elsevier 2019 Materials science & engineering. C, Materials for Vol.103 No.-

<P><B>Abstract</B></P> <P>We have designed and characterized an injectable, electrostatically bonded, <I>in situ</I>–forming hydrogel system consisting of a cationic polyelectrolyte [(methoxy)polyethylene glycol-<I>b</I>-(poly(ε-caprolactone)-<I>ran</I>-poly(L-lactic acid)] (MP) copolymer derivatized with an amine group (MP-NH<SUB>2</SUB>) and anionic BMP2. To the best of our knowledge, there have been hardly any studies that have investigated electrostatically bonded, <I>in situ</I>–forming hydrogel systems consisting of MP-NH<SUB>2</SUB> and BMP2, with respect to how they promote <I>in vivo</I> osteogenic differentiation of human turbinate mesenchymal stem cells (hTMSCs). Injectable formulations almost immediately formed an electrostatically loaded hydrogel depot containing BMP2, upon injection into mice. The hydrogel features and stability of BMP2 inside the hydrogel were significantly affected by the electrostatic attraction between BMP2 and MP-NH<SUB>2</SUB>. Additionally, the time BMP2 spent inside the hydrogel depot was prolonged <I>in vivo</I>, as evidenced by <I>in vivo</I> near-infrared fluorescence imaging. Biocompatibility was demonstrated by the fact that hTMSCs survived <I>in vivo</I>, even after 8 weeks and even though relatively few macrophages were in the hydrogel depot. The osteogenic capacity of the electrostatically loaded hydrogel implants containing BMP2 was higher than that of a hydrogel that was simply loaded with BMP2, as evidenced by Alizarin Red S, von Kossa, and hematoxylin and eosin staining as well as osteonectin, osteopontin, osteocalcin, and type 1α collagen mRNA expression. The results confirmed that our injectable, <I>in situ</I>–forming hydrogel system, electrostatically loaded with BMP2, can enhance <I>in vivo</I> osteogenic differentiation of hTMSCs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An injectable, electrostatically bonded, <I>in situ</I>–forming hydrogel system consisting of a cationic polyelectrolyte copolymer derivatized with an amine group and anionic BMP2 was prepared. </LI> <LI> The hydrogel features and stability of BMP2 inside the hydrogel were significantly affected by the electrostatic attraction between BMP2 and cationic polyelectrolyte copolymer. </LI> <LI> The electrostatically loaded hydrogel enhanced osteogenic differentiation of human turbinate mesenchymal stem cells better than one with simple loading of BMP2. </LI> </UL> </P>