N₂/ CH₄가스비에 따른 Hydrogenated Amorphous Carbon Nitride 박막의 특성

장홍규(H. K. Jang),김근식(G. S. Kim),황보상우(S. W. Whangbo),이연승(Y. S. Lee),황정남(C. N. Whang),유영조(Y. Z. Yoo),김효근(H. G. Kim) 한국진공학회(ASCT) 1998 Applied Science and Convergence Technology Vol.7 No.3

DC saddle-field-plasma-enhanced chemical-vapor deposition(PECVD) 장치를 이용하여 상온에서 p-type Si (100) 기판위에 hydrogenated amorphous carbon nitride [a-C:H(N)]박막을 증착하였다. 원료가스인 CH₄과 N₂의 전체압력은 90 mTorr로 고정하고 N₂/CH₄비를 0에서 4까지 변화하면서 제작한 a-C:H(N) 박막의 미세 구조의 변화를 연구하였다. 진공조의 도달 진공도는 1×10^(-6) Torr이고, 본 실험시 CH₄+N₂가스의 유량은 5 sc㎝으로 고정하고 배기량을 조절하여 진공조의 가스 압력을 90 mTorr로 고정하였으며 기판에 200 V의 직류 bias 전압을 인가하였다. α-step과 X-ray photoelectron spectroscopy(XPS)를 이용한 분석결과 N₂/CH₄비가 0에서 0.5로 증가함에 따라 박막 두께는 4840 Å에서 2600 Å으로 급격히 감소하였으며, 박막내의 탄소에 대한 질소함유량(N/C비)는 N₂/CH₄비가 4일때 최대 0.25로 증가하는 것을 확인하였다. 또한 XPS 스펙트럼의 fitting 결과 N₂/CH₄비가 증가할수록 CN결합이 증가하였다. Fourier Transformation Infrared (FT-IR) 분석결과 N₂/CH₄비가 증가함에 따라 박막내의 C-H 결합은 감소하고, N-H, C≡N 결합은 증가하였다. Optical bandgap 측정 결 과 N₂/CH₄비가 0에서 4로 증가함에 따라 a-C:H(N)박막의 bandgap 에너지는 2.53 eV에서 2.3 eV로 감소하는 것을 확인하였다. Hydrogenated amorphous carbon nitride[a-C:H(N)] films were deposited on p-type Si(100) at room temperature with substrate bias voltage of 200 V by DC saddle-field plasma-enhanced chemical vapor deposition. Effects of the ratio of N₂to CH₄(N₂/CH₄), in the range of 0 and 4 on such properties as optical properties, microstucture, relative fraction of nitrogen and carbon, etc. of the films have been investigated. The thickness of the a-C:H(N) film was abruptly decreased with the addition of nitrogen, but at N₂/CH₄> 0.5, the thickness of the film gradually decreased with the increase of the N₂/CH₄. The ratio of N to C(N/C) of the films was saturated at 0.25 with the increase of N₂/CH₄. N-H, C≡N bonds of the films increased but C-H bond decreased with the increase of N₂/CH₄. Optical band gap energy of the film decreased from 2.53 eV deposited with pure methane to 2.3 eV at the ratio of N₂/CH₄=4.

Mechanical and electrical properties of micron-thick nitrogen-doped tetrahedral amorphous carbon coatings

Jang, Y.J.,Kang, Y.J.,Kitazume, K.,Umehara, N.,Kim, J. Elsevier 2016 Diamond and related materials Vol.69 No.-

<P>The effect of nitrogen doping on the mechanical and electrical performance of single-layer tetrahedral amorphous carbon (ta-C:N) coatings of up to 1 pm in thickness was investigated using a custom-made filtered cathode vacuum arc (FCVA). The results obtained revealed that the hardness and electrical resistance of the coatings decreased from 65 +/- 4.8 GPa (3 k Omega/square) to 25 +/- 2.4 GPa (10 Omega/square) with increasing nitrogen gas ratio, which indicates that nitrogen doping occurs through substitution in the sp(2) phase. Subsequent AES analysis showed that the N/C ratio in the ta-C:N thick-film coatings ranged from 0.03 to 029 and increased with the nitrogen flow rate. Variation in the G-peak positions and I(D)/I(G) ratio exhibit a similar trend. It is concluded from these results that micron-thick ta-C:N films have the potential to be used in a wide range of functional coating applications in electronics. (C) 2016 Elsevier B.V. All rights reserved.</P>

Diffractive excitation of 14.6-, 60-, and 200-GeV/nucleon ^16O and 14.6-GeV/nucleon ^28Si nuclei in nuclear emulsion

Bahk, S. Y.,Chang, S. D.,Cheon, B. G.,Cho, J. H.,Jang, H. I.,Hahn, C. H.,Hara, T.,Lim, G. Y.,Kang, J. S.,Kim, C. O.,Kim, J. Y.,Kim, K. Y.,Kim, S. N.,Kim, T. I.,Kim, T. Y.,Koo, D. G.,Lee, S. B.,Lim, I. 慶尙大學校 기초과학연구소 1991 基礎科學硏究所報 Vol.7 No.-

An angular method of identifying diffractive excitation(DE) events for interactions of a hadron beam in nuclear emulsion is applied to identifying DE events in interactions of heavy ions beams. The "apparent" mean free paths (MEP) of DE processes for ^16O(^28Si) beams are 1.00±0.12, 2.4^_1.6_-0.7, and 2.2±0.4(1.5±0.2)m, respectively, at 200, 60 and 14.6 GeV/nucleon, which corresponds to 20-10% fo the MFP for total inelastic interactions. Distinctive features of diffractively excited nuclei are discussed.

Superconductivity of Y_(1.2) Ba_(0.8)CuO_(4-y)

Jang, M.S.,Y.W Park,Kim, J.W.,Kim, J.N.,Ro, J.H.,Kim, H.K. 부산대학교 기초과학연구소 1988 부산대학교 기초과학연구소 연구논문집 Vol.8 No.-

새로운 Y-Ba-Cu 산화물 세라믹의 초전도성을 연구하기 위해 전기저항, 자화율 그리고 열전력을 측정했으며, 우리의 2가지 시료에 대해 일치되는 결과를 얻었다. 90K 근방에서 초전도성 상전이가 일어났으며, 상전이 온도는 시료에 부하된 전류밀도에 대해 매우 민감했다. 그리고 열전력 측정 결과에 의하면 상전이 점 부근에서 phonon 방출의 증가를 보이므로 P-형 초전도체이다.

자유드로잉 제품과 패드를 설치한 드로잉 제품의 특성

고관영,명노훈,하종성,이창수,최창권,최병용,허기영,김광수,김동수,장종훈,장윤철,김세환,오정민,하민정,박향자 울산과학대학 2000 연구논문집 Vol.27 No.1

본 연구는 자체 제작한 전체 패드가 부착된 드로잉 금형을 이용하여 SUS, 연강, AI, 6:4황동 판재를 드로잉 가공하여 생산된 제품의 특성을 자유드로잉 하여 얻은 제품의 특성과 비교 분석하였다. SUS 판재의 경우 제품에 발생하는 현상은 벽 주름, 구변주름, 수직 파단, 드로잉상처, 이어링이 발생하였으며 길이변화는 펀치어깨부분에서 가장 많이 늘어남을 볼 수 있었고 벽 주름 부분에 있어서 접혀진 부분은 상대적으로 적게 늘어남을 볼 수 있었다. 연강 판재는 SUS 판재에서 보여준 현상을 나타내었으나 SUS 판재에 비해 수직 파단은 적게 일어난 반면 이어링이 더 크게 일어났다. AI 판재의 경우 수직 파단은 일어나지 않았으나 플랜지 주름과 밑면터짐이 발생하였다. 6:4황동의 경우는 전체패드의 AI 판재 드로잉에서와 같이 밑면터짐과 플랜지 주름의 발생이 일어났다.

1.88A GeV ^56Fe 중이온에 의해 원자핵건판 내에서 회절들뜸 및 준회절들뜸 기구로 생긴 다중발생

김종오,김태연,천병구,박인곤,송진섭,윤천실,박상렬,이경언,김재률,김태익,박명렬,임인택,장한일,박복남 慶尙大學校 기초과학연구소 1990 基礎科學硏究所報 Vol.6 No.-

원자핵건판 내에서 1.88A GeV의 에너지를 갖는 ^56Fe 중이온(heavy ion)의 평균자유행로는 비적추적법(along-the-track scanning method)을 사용하여 8.01±0.27㎝로 측정되었다. ^56Fe 주이온에 의한 회절들뜸반응을 KHP 판정법으로 찾아내었으며, 회절들뜸반응에 대한 평균자유행로는 0.86±0.10m로 측정되었다. 입사중이온의 정지계 내에서 ^56Fe 중이온에 의한 80개의 회절들뜸 및 준회절들뜸반응에 대한 알파입자와 단일하전 입자의 의사신속도 분포는 각각 (γ_a-η_b)_max=3.31, (γ_a-η_b)_max=2.30에서 최대값을 갖는 가우스분포함수 형태를 이루었다. By employing the method of along-the -track scanning. the mean free path of inelastic collisions for 1.8A GeV^56Fe heavy ion in nuclear emulsion is measured to be 8.01±0.27㎝. "Diffractive Excitation" events are identified by using the KHP method and the mean free path of diffractive excitation is measured to be 0.86±0.10m. The distributions of pseudorapidities of alpha and singly-charged fragments for diffractive excitation of 1.88A GeV ^Fe heavy ion are well fitted by Gaussian distribution function with peaks having (γ_a-η_b)_max=3.30 and (γ_p-η_b)_max=2.24.

Relation between renal function and neointimal tissue characteristics after drug-eluting stent implantation: Virtual histology-intravascular ultrasound analysis

Hong, Y.J.,Jeong, M.H.,Choi, Y.H.,Park, S.Y.,Rhew, S.H.,Kim, S.S.,Jeong, Y.W.,Jeong, H.C.,Cho, J.Y.,Jang, S.Y.,Lee, K.H.,Park, K.H.,Sim, D.S.,Yoon, N.S.,Yoon, H.J.,Kim, K.H.,Park, H.W.,Kim, J.H.,Ahn, Japanese College of Cardiology 2014 Journal of cardiology Vol.64 No.2

Background: Few data are available about neointimal tissue characteristics after drug-eluting stent (DES) implantation in patients with decreased renal function. We used virtual histology-intravascular ultrasound (VH-IVUS) to assess the neointimal tissue characteristics according to the baseline renal function. Methods: We compared neointimal tissue components between patients with chronic kidney disease (CKD) [n=19, estimated creatinine clearance (CrCl) <60mL/min] and those without CKD (n=229). The region of interest was placed between the luminal border and the inner border of the stent struts and tissue components were reported as percentages of neointimal volume. Results: Mean follow-up durations between DES implantation and follow-up VH-IVUS study were 12.0+/-4.1 months in the CKD group and 11.4+/-5.6 months in the non-CKD group (p=0.519). At follow-up, neointima volume was significantly greater (72+/-47mm<SUP>3</SUP> vs. 47+/-26 mm<SUP>3</SUP>, p<0.001) and %neointima necrotic core (NC) volume was significantly greater (25.0+/-11.4% vs. 17.9+/-10.2%, p=0.012) in the CKD group compared with the non-CKD group. There was negative correlation between CrCl and neointima volume (r=-0.250, p<0.001), however, there was no significant correlation between CrCl and %neointima NC volume (r=-0.034, p=0.591). The only independent predictor of follow-up %neointima NC volume ≥10% was neointima volume (odds ratio 1.025, 95% confidence interval 1.013-1.036, p<0.001). Conclusions: Renal function was associated with in-stent neointimal growth, but it was not associated with neointima NC formation. Instead, the amount of neointima was associated with more neoatherosclerosis in patients who underwent DES implantation.

테트라히메나 동적 제어에 따른 유동 특성 연구

장용희(Y.H. Jang),김지훈(J.H. Kim),트란트룽휴(H.T. Trung),변도영(D.Y. Byun),남성원(S.W. Nμmam),박성수(S.S. Park),김민준(M.J. Kim) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11

This paper describes a dynamic motion of tetrahymena in a low Reynolds number fluidic environment. We visualize the flow field induced by Tetrahymena in terms of galvanotaxis. Electrical stimulation(AC/DC) cause a change of swimming direction and movement toward the cathode. And we propose the micro-delivery system which attached on micro-structure by using Poly-l-lysine. This motivation of this work can be realized the propelled system and transporter as a micro-robot containing fluid.

Pilot-scale synthesis of a zirconium-benzenedicarboxylate UiO-66 for CO₂ adsorption and catalysis

Kim, S.N.,Lee, Y.R.,Hong, S.H.,Jang, M.S.,Ahn, W.S. Elsevier Science Publishers 2015 CATALYSIS TODAY - Vol.245 No.-

Synthesis of a zirconium-benzenedicarboxylate, UiO-66, was carried out in increasing production scales of 250mL, 1L and 5L at 393K. Investigation on the effect of synthesis parameters on the product yield and textural properties was carried out using autoclaves of 250mL capacity, whereas systematic scale up works were conducted using glass reactors fitted with condensers under ambient pressure conditions. Finally, 100L pilot scale synthesis of UiO-66 was carried out using commercial terephthalic acid as ligand with industrial-grade dimethylformamide solvent. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and N<SUB>2</SUB> adsorption-desorption measurements. The pelletized UiO-66 using polyvinyl alcohol as a binder demonstrated excellent CO<SUB>2</SUB>/N<SUB>2</SUB> separation (36:1) with moderately high CO<SUB>2</SUB> adsorption capacity (191mg/g) at 20bar room temperature conditions. UiO-66 also showed excellent catalytic activity in cycloaddition of CO<SUB>2</SUB> to styrene oxide at 2.0MPa and 373K with close to 100% selectivity to carbonate. No appreciable particle size effect on the catalytic activity was observed, and UiO-66 could be reused 3 times without loss of catalytic activity.

Eclalbasaponin II Ameliorates the Cognitive Impairment Induced by Cholinergic Blockade in Mice

Jung, W. Y.,Kim, H.,Jeon, S. J.,Park, H. J.,Choi, H. J.,Kim, N. J.,Kim, D. H.,Jang, D. S.,Ryu, J. H. Springer Science + Business Media 2018 Neurochem Res Vol.43 No.2

<P>Eclalbasaponin II derived from Eclipta prostrata L. (Asteraceae) has been reported to have anti-fibrotic, anti-bacterial and autophagic activities, but its effect on cognitive function has not been investigated. We studied the effect of eclalbasaponin II on cholinergic blockade-induced memory impairment in mice using the passive avoidance, Y-maze, and Morris water maze tasks. Eclalbasaponin II (10 or 20 mg/kg, p.o.) significantly ameliorated the cognitive dysfunction induced by scopolamine in the passive avoidance, Y-maze, and the Morris water maze tasks. To identify the mechanism of the memory-ameliorating effect of eclalbasaponin II, acetylcholinesterase (AChE) activity assay, Western blot analysis and electrophysiology were conducted. Eclalbasaponin II inhibited the AChE activity in ex vivo study, and the administration of eclalbasaponin II and its metabolite, echinocystic acid, increased the phosphorylation levels of memory-related signaling molecules, including protein kinase B (Akt) and glycogen synthase kinase-3 beta (GSK-3 beta), in the hippocampus. Although eclalbasaponin II did not affect hippocampal long term potentiation (LTP), echinocystic acid significantly enhanced hippocampal LTP formation (30 mu M). These results suggest that eclalbasaponin II ameliorates cholinergic blockade-induced cognitive impairment via AChE inhibition, LTP formation and the activation of Akt-GSK-3 beta signaling, and that eclalbasaponin II may be a useful to treat cognitive impairment derived from cholinergic dysfunction.</P>