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.

관동맥질환에서 저밀도 지단백 입자 크기의 분포

임효영,김인숙,승기배,강동헌,전두수,장기육,박준철,이수영,홍순조,최규보 대한순환기학회 1998 Korean Circulation Journal Vol.28 No.8

배구 경기 시 포지션별 공격점프횟수와 혈중 젖산농도 비교분석

위승두,김민철,박정희 조선대학교 스포츠과학연구소 2001 스포츠科學硏究 Vol.12 No.-

The purpose of this study was to measure the number of Jumps for spike in each position and to find out in what position the most physical fitness was consumed. The subjects were 18 male players who were divided three groups of six One was the left, another was the right. the other was the center. The apparatus was Lactate Analyzer(YSI U.S.A). The results of study were as follows : 1. In male volleyball game, the number of jumps for spike in each position was like that; The left was 32, the center was 46. the right was 26. So, the center most frequently attempted for spike during 5set. 2. In the group of the left, after spiking the blood lactate concentration was changed from 2.32±0.23mM to 4.5±0.90mM and in the center it was changed from 2.23±0. 23mM to 8.58±2.10mM and in the right it was changed from 2.35mM to 5.51±1.66mM So, in the group of the center the most the blood lactate concentration was increased. 3. Before spiking there was of not difference between the in-group and the inter-group, but after spiking there was a little difference-(P <.01)-for the inter-group. 4. After spiking there was a little difference-(P <.01)-between the center and the leftand there was also a little difference-(P <.05)-between the center and the right.

초기 진동 특성치가 측정되지 않은 캔틸레버 보의 손상 추정 방법에 관한 연구

문환두,백승철 安東大學校 工業技術硏究所 1996 공업기술연구논문집 Vol.3 No.1

Most civil engineering structures are apt to experience structural damages over their service lives caused by adverse loadings. Accumulation of structural damages over a long period time might cause catastrophic structural failure. Therefore, maintenance and retrofitting of existing structures is essential for assuring the safety of the existing structures. The damage detection algorithm must be exact and reliable. There have recently been attempts to evaluate the structural damage utilizing the experimentally measured response data. But the baseline modal responses were required to evaluate the structural damage. The purpose of this paper is to present the damage detection algorithm for structures without baseline modal responses. Natural frequencies of a structure with a transverse surface crack extending uniformly along the width is measured experimentally. Using only the natural frequencies of a damaged structure, it has been found that the location and degree of damage are reasonably determined. The damage detection algorithm was applied to identify a crack in a cantilever beam.

장기간 운동이 중년남성 혈액성분과 전해질 반응에 미치는 영향

위승두 木浦大學校應用스포츠 科學硏究所 2003 스포츠 科學硏究 Vol.2 No.-

This study was designed to investigate the effects of long~term training on the lipid(triglyceride, cholesterol) and lipoprotein(HDL-cholesterol). The subjects consisted of 9 junior female athletes(exercise career, three month ; A group) and 6 athletes(exercise career fifteen month ; B group) and 12 junior school girls as control group(C group) who all were about thirteen years old. Both athlete groups(A, B group) were continuous to participate in six month training and their blood samples were collected at pre mid(after three month) and post(after six month). The control subjects donated their blood at pre and post(after six month). The collected blood were analyzed for the triglyceride, cholesterol, High density lipopro-tein cholesterol and HDL-C/TC ratio. The result through the statistical analysis of this data were summarized as follows The pre-levels of triglyceride and total cholesterol in Athlete group, especially Bgroup were lower than those in Non-athlete group(p<0.01). HDL-C level and HDL-C/TC ratio were highest in B group among three group(p<0.05). HDL-C level and HDL-C/TC ratio in both athlete group, especially A group were significantly decreased after three and six month(p<0.01) while in control group all item were not changed. The result indicated by three month training and the change of HDL-C need more long term training(more than three month).

협동조합법에 관한 비교법적 연구

양승두 연세대학교 행정대학원 1982 延世行政論叢 Vol.9 No.-

사람 胎盤組織 膜 結合 Adenosine Deaminase의 性狀에 關한 硏究

황병두,홍승원 충남대학교 의과대학 지역사회의학연구소 1982 충남의대잡지 Vol.9 No.1

The properties of plasma membrane bound adenosine deaminase(ADase) from human placenta have been investigated. The enzyme exhibits a broad pH optimum from pH 6 to 8 and is heat labile, being completely inactivated by heat treatment at 70℃ for 10 minutes. The enzyme is not effected at pH 7 by 2 mM. Li^+, Mg^2+, Ca^2+, Mn^2+, Co^2+, Fe^2+ and Zn^2+, while the enzyme is activated by 2 mM Ca^2+ and Co^2+ at pH 8 and inhibited by 2 mM Cu^2+ independent of pH. The enzyme activity is completely recovered by EDTA (4 mM) only in case of adding Cue+ after preincubation of enzyme with substrate. The apparent Michaelis constant of the enzyme for adenosine is 58 μM. From the above result, it is suggested that the enzyme is different from ADase of soluble fraction of human placenta.

水素化된 非晶質 게르마늄의 特性調査(Ⅰ)

梁承勳,李原鎭,朴奉斗 慶北大學校 1985 論文集 Vol.39 No.-

Reactive thermal evaporation(RTE) was developed as a new method to deposit hydrogenated amorphous germanium films. RTE was carried out by the evaporation of high purity polycrystalline germanium in an atmosphere of hydrogen plasma produced by high voltage AC discharge of molecular hydrogen. Electrical conductivity and its annealing behavior, electron probe micro-analyzer and scanning electron microscopy were used to characterize the samples. Optimal conditions of sample preparation (from electronic point of view) were determined to be substrate temperature of 200℃ and hydrogen pressure of 1 Torr. Crucible type was proved to have an influence on the sample properties. The sample prepared at the optimum conditions shows the activated type conduction above room temperature.

心臟組織 Cyclic 3':5'-Nucleotide Phosphodiesterase- Activator의 Methylation

李聖鎭,林圭,黃炳斗 충남대학교 의과대학 지역사회의학연구소 1986 충남의대잡지 Vol.13 No.1

Cyclic 3':5'-nucleotide phosphodiesterase-activator(calmodulin) has been purified from bovine heart approximately 850-fold, and investigated methylation of calmodulin by protein methylase Ⅱ and the effect on the calmodulin-induced activation of phosphodiesterase by methylated calmodulin. Calmodulin-induced activation of phosphodiesterase by purified calmodulin is stimulated 3.1-fold and its saturating concentraticn is about 0.4 ㎍ protein. The purified calmodulin appears single protein band by SDS/polyacryamide gel electrophoresis (pH 2.4) and the calmodulin-induced activation of phosphodiesterase is completely inhibited by adding 100 ㎍ of fluphenazine and 1 mM of EGTA. The relative substrate efficiency of calmodulin by protein methylase Ⅱ is about 70% compare with histone IIA-S. The methylated calmodulin inhibits about 20% calmodulin-induced activation of phosphodiesterase compare with that of nonmethylated calmodulin. Methylation rate of calmodulin is constant, independant of Ca^2+ presence. Calmodulin-induced activation of phosphodiesterase by methylated calmodulin is completely inhibited in the presence of 1 mM EGTA. From the above results, inhibitory mechanism of calmodulin-induced activation of phosphodiesterase by methylated calmodulin is discussed.

中共社會의 脫階層化: 이데올리기的 平等主義志向과 그 限界

洪斗承 서울대학교 사회과학연구소 1981 社會科學과政策硏究 Vol.3 No.2