• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년 추계학술대회논문집
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• pp.181-185
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• 2008

In this study, we attempted to quantify the relative importance of assumptions regarding blood rheology. Three patient-specific carotid bifurcation geometries and time-varying flow rates were obtained using magnetic resonance imaging. For each subject, CFD simulations were carried out assuming two different non-Newtonian rheology models (Carreau and Ballyk models) and rescaled Newtonian viscosities based on characteristic shear rates to account for the shear-thinning property of blood. The sensitivity of WSS and oscillatory shear index (OSI) were contextualized with respect to the reproducibility of the reconstructed geometry and to assumptions regarding the inlet boundary conditions. We conclude that the assumption of Newtonian fluid is reasonable for studies aimed at quantifying the distribution of WSS-based extrema in an image-based CFD model of carotid bifurcation.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1451-1455
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• 2007

MAGLEV(Magnetic Levitation) with Middle-low speed be classified as a kind of LRT(Light Rail Transit) in KOREA. Also this vehicle has adopted LIM propulsion method. The MAGLEV has adopted LIM type in operational or developing model in the world. The power rail of LIM is very similar with the 3th rail of LRT in the functional property but the structure and shape of power rail is different with that. WE have to search the optimal power rail system for Korean MAGLEV vehicle. In this paper, we suggest the conceptual design and direction of design for power rail of Korean MAGLEV developing.

• The Korean Journal of Ceramics
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• 제6권4호
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• pp.364-369
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• 2000

Silicon nitride with adding La$_2$O$_3$ was sintered by gas pressure sintering (GPS) technique at $1950^{\circ}C$, in $N_2$ gas at 3 MPa, for 2h. Mechanical properties such as hardness, flexural strength, and fracture toughness were determined as a function of the GPS holding time and the contents of La$_2$O$_3$ in silicon nitride. Also machinability of silicon nitride ball with various GPS holding time and amount of La$_2$O$_3$ was evaluated by magnetic fluid grinding (MFG) method. In this study it was found that machinability was influenced significantly with La$_2$O$_3$ contents. However, the different GPS holding time did not affect the machinability very much.

• Bulletin of the Korean Chemical Society
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• 제33권5호
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• pp.1675-1680
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• 2012

Three new cyanide-bridged $Cr^{III}Mn^{II}$ binuclear complexes, $[Mn(phen)_2Cl][Cr(bpmb)(CN)_2]{\cdot}H_2O$ ($\mathbf{1}$) (phen = 1,10-phenanthroline, $bpdmb^{2-}$ = 1,2-bis(pyridine-2-carboxamido)-4-methyl-benzenate), $[Mn(phen)_2Cl][Cr(bpmb)-(CN)_2]{\cdot}H_2O$ ($\mathbf{2}$) ($bpdmb^{2-}$ = 1,2-bis(pyridine-2-carboxamido)-4,5-dimethyl-benzenate), and $[Mn(phen)_2Cl]-[Cr(bpClb)(CN)_2]{\cdot}CH_3OH{\cdot}H_2O$ ($\mathbf{3}$) ($bpClb^{2-}$ = 1,2-bis(pyridine-2-carboxamido)-4-chloro-benzenate) were obtained based on $Mn(phen)_2Cl_2$ and a series of dicyanidechromate(III) building blocks. Single crystal X-ray diffraction analysis shows the structures of the three complexes are dimeric type with two different metal centers linked by a cyanide group from corresponding dicyanidechromate(III) building block. Magnetic investigations indicate the existence of relatively weak antiferromagnetic coupling between Cr(III) and Mn(II) ions with best-fit constants $J_{CrMn}=-2.78(5)cm^{-1}$ for $\mathbf{1}$, $J_{CrMn}=-3.02(2)cm^{-1}$ for $\mathbf{2}$ and $J_{CrMn}=-2.27(3)cm^{-1}$ for $\mathbf{3}$ based on the spin exchange Hamiltonian = $-2J_{CrMn}\hat{S}_{Cr}\hat{S}_{Mn}$. The magneto-structural correlation of cyanide-bridged $Cr^{III}Mn^{II}$ complexes has been discussed at last.

• Elastomers and Composites
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• 제42권3호
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• pp.151-158
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• 2007

최근 들어 전기적, 기계적 성질이 우수한 다중벽탄소나노튜브(Multi-Walled Carbon Nanotubes)/고분자 복합재료에 대한 연구가 활발히 진행 중이다. 본 연구에서는 모듈라 치합형 동방형 회전 이축 압출기(Modular Intermeshing Co-Rotating Twin Screw Extruder, L/D=42)를 이용하여 PMMA/MWNT 복합체를 제조하였다. 이렇게 제조된 PMMA/MWNT 복합체의 표면저항을 측정한 결과 MWNT의 함량이 4 wt% 일 때 $10^4{\Omega}/sq$를 나타내어 전자파차폐(Electronic Magnetic Interference) 물질로 응용할 수 있는 가능성을 확인하였다. 그리고 열중량 분석기 (Thermogravimetric Analysis), 시차주사열량계(Differential Scanning Calorimeter)를 이용한 열적특성, 주사전자현미경(Scanning Electron Microscopy)을 통하여 형태학적 변화를 분석하였다. 또한 유변학적 특성을 알아보기 위해 용융흐름지수(Melt Flow Index)를 측정하였다.

• 한국자기학회지
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• 제21권4호
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• pp.132-135
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• 2011

초연자성을 갖는 코네틱(NiFeCuMo) 박막을 NiFe 박막 사이에 삽입한 삼층박막 위에 반강자성체 FeMn을 증착한 다층박막에서 NiFe와 NiFeCuMo 박막의 두께에 따른 교환결합력과 보자력에 관한 특성을 조사하였다. 특히 NiFeCuMo 박막의 두께가 1 nm일 때 NiFe 박막 사이에 삽입한 삼층박막 위에 반강자성체 FeMn을 증착한 다층박막의 교환결합력은 최댓값을 나타내었다. 고정층과 자유층에 각각 NiFeCuMo 박막을 삽입하여 초연자성의 바이오센서용 거대자기저항-스핀밸브(giant magnetoresistive-spin valves; GMR-SV) 소자를 개발할 수 있는 가능성을 보여주었다.

• 한국초전도ㆍ저온공학회논문지
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• 제24권3호
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• pp.57-61
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• 2022

One of the major applications of REBCO coated conductor (CC) tapes is in superconducting magnets or coils that are designed for high magnet fields. For such applications, the CC tapes were exposed to a high level of stresses which includes uniaxial tensile or transverse compressive stresses resulting from a large magnetic field. Thus, CC tapes should endure such mechanical load or deformation that can influence their electromechanical performance during manufacturing, cool-down, and operation. It has been reported that the main cause of critical current (I_c) degradation in CC tapes utilized in coil windings for superconducting magnets was the delamination due to transversely applied stresses. In most high-magnetic-field applications, the operating limits of the CC tapes will likely be imposed by the electromechanical properties together with its I_c dependence on temperature and magnetic field. In this study, we examined the influence of the transverse compressive stress on the I_c degradation behaviors in various commercially available CC tapes which is important for magnet design Four differently processed REBCO CC tapes were adopted to examine their I_c degradation behaviors under transverse compression using an anvil test method and a newly developed instantaneous I_c measurement system. As a result, all REBCO CC tapes adopted showed robustness against transverse compressive stresses for REBCO coils, notably at transverse compressive stresses until 250 MPa. When the applied stress further increased, different Ic degradation behaviors were observed depending on the sample. Among them, the one that was fabricated by the IBAD/MOCVD process showed the highest compressive stress tolerance.

• 한국미생물·생명공학회지
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• 제45권3호
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• pp.209-217
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• 2017

In the enduring investigation of the bioactive microbes, Pseudomonas aeruginosa strain (referred to as CGK-KS-1 (ICTB-315)), isolated from Chumathang hot spring, Ladakh, and India, was identified to possess a major bioactive fraction with antimicrobial and anti-biofilm properties. This bioactive metabolite was purified through bioactivity-guided fractionation. The chemical structure of this major compound was elucidated as phenazine-1-carboxamide (PCN) based on $^1H$ and $^{13}C$ NMR, FT-IR, EI-HR-MS and 2D NMR spectroscopic techniques. In the current study, PCN exhibited antimicrobial activity with MIC values ranging between $1.9-3.9{\mu}g/ml$ against various test human pathogens and Xanthomonas spp. PCN showed the anti-biofilm property with the $IC_{50}$ values ranging from 17.04 to $60.7{\mu}M$ against different test pathogens. The in silico docking studies showed PCN strongly interacted with various proteins of different Xanthomonas spp. with high binding energies. We report herein for the first time the anti-biofilm property and the docking studies of PCN. The extrolite from P. aeruginosa strain CGK-KS-1 showed promising bioactivities and may be considered as a potential candidate for application in various biocontrol strategies.

• 자원환경지질
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• 제46권3호
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• pp.207-214
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• 2013

2012년 통가해저열수광상 개발 사업의 일환으로 통가아크 해저산 TA25에서 ROV와 GTV를 이용하여 열수황화물광체를 채취하였다. 채취된 광체 중 본 연구에서는 약 $200^{\circ}C$의 열수분출을 보인 고온성 활성침니(ROV01), $80^{\circ}C$의 열수분출을 보인 저온성 활성침니(GTV01), 그리고 비활성침니(ROV02)를 이용하여, 암석자기학적 특성을 규명하고 이를 바탕으로 광체의 진화과정을 알아보고자 하였다. ROV01의 자기적 특성은 주로 자류철석에 의해 나타나며, GTV01의 경우 광체내부는 자류철석이 주로 나타나지만 외곽으로 갈수록 자류철석과 적철석이 혼재하게 된다. 비활성침니인 ROV02는 오랜 산화작용으로 인해 외곽에서 적철석뿐만 아니라 침철석이 자류철석과 함께 나타나고, 최외곽에서는 magnetotactic bacteria의 작용에 의해 자철석이 존재한다. 포화잔류자화(saturation magnetic remanent magnetization, SIRM), 비자기이력잔류자화(anhysteretic remanent magnetization, ARM)/SIRM으로 나타낸 자성광물의 함량과 입자크기 변화는 침니의 특성에 따라 뚜렷한 차이가 난다. 고온의 ROV01에서 가장 적은 함량과 작은 입자크기를 보이며, 저온의 GTV01에서 점차 증가하다가 비활성침니인 ROV02에서 가장 높은 함량과 큰 입자크기를 나타내게 된다. 이러한 결과는 자성광물의 종류, 함량, 입자크기 변화 등의 암석자기학적 특성을 이용하여 기존 광물학적 접근방법으로 추적에 한계가 있었던 열수황화물광체의 진화과정에 대한 정보를 획득할 수 있을 것으로 판단된다.

• 한국자기학회지
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• 제10권4호
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• pp.165-170
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• 2000

Fe-Hf-N 연자성 박막의 물리적, 자기적 특성에 미치는 열처리 영향에 대하여 고찰하였다. Fe-Hf-N 연자성 박막을 질소분위기에서 열처리 할 경우 표면에 Fe$_2$O$_3$-Fe$_3$O$_4$으로 구성된 산화층이 생성되었고, 이 산화층 아래 Fe-Hf-O-N층이 생성되었다. 열처리 온도의 증가에 따라 Fe$_2$O$_3$-Fe$_3$O$_4$ 산화층과 Fe-Hf-O-N 층의 두께가 증가하였고, Fe$_2$O$_3$-Fe$_3$O$_4$산화층을 제외한 박막의 두께는 열처리전과 같았다. 열처리한 박막에서 표면에 생성된 Fe$_2$O$_3$-Fe$_3$O$_4$산화층의 두께를 제외하고 계산한 박막의 연자기 특성은 열처리 전의 연자기 특성에 비해 약간 떨어지는 것으로 나타났다. 그러므로, Fe-Hf-O-N층은 박막 전체의 연자기 특성을 크게 떨어뜨리지 않으며, 열처리 후 박막 전체의 연자기 특성은 Fe-Hf-O-N과 Fe-Hf-N의 다층막의 연자기 특성을 나타내는 것으로 생각된다.