• Journal of Korean Neurosurgical Society
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• 제51권5호
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• pp.292-295
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• 2012

Many reports have been published on complications related to middle cerebral artery (MCA) aneurysm surgical clipping procedures. We report an emergency intracranial in situ bypass surgery case which was performed as a rescue procedure after aneurysmal neck laceration during clipping of an MCA large aneurysm. In this case, we performed in situ M3-superficial temporal artery (STA) interposition graft-M3 bypass procedure. If a STA-MCA anastomosis is not available under MCA flow obstruction, we can consider an emergency in situ MCA-MCA bypass procedure with or without an STA interposition graft.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2013년도 자성 및 자성재료 국제학술대회
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• pp.29-29
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• 2013

We predict agigantic perpendicular magnetocrystalline anisotropy (MCA) in Fe (001) capped by 5d transition metal (TM) overlayers by using first principles calculations. Analysis of atom-by-atom contribution to MCA reveals that gigantic MCA as large as 11 meV/TM originates not from Fe atoms but from the 5d TMs through the strong spin-orbit coupling. More specifically, it is the hybridization between TM and Fe d orbitals that also induces non-negligible magnetic moments in TM. Furthermore, spin-channel decompositions of MCA matrix with and without the presence of Fe substrate identify the electronic origin of the perpendicular MCA that the down-down channel contribution plays the most crucial role for the sign changes of MCA of TM overlayers upon the hybridization with Fe-3d.

• 대한수의학회지
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• 제26권1호
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• pp.117-124
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• 1986

The present study was undertaken to evaluate rosette formation and NK activity of splenic lymphocytes in 3-methylcholanthrene (MCA) treated mice. Mice were sensitized iv with 0.1ml of 1% sheep red blood cell (SRBC) suspension were treated with a single ip injection of olive oil alone or with different doses of MCA in oil at various time before or after sensitization, and were challenged at 4 days after SRBC. Rosette formation and NK activity of splenic lymphocytes were measured at 24 hours after challenge. Erythrocyte(E) rosette formation of splenic lymphocytes was significantly depressed in mouse treated with large dose of MCA (5~50mg) regardless of injecting time. But, there was no difference in the response between the treated with small dose of MCA (0.5mg). Whereas erythrocyte-antibody(EA) rosette or erythrocyte-antibody-complement(EAC) rosette forming cells were significantly depressed by MCA. Under small dose of MCA (0.5mg), any difference of NK activity was not observed in all course of injecting time. But, under large dose of MCA, the activity was markedly inhibited to about half the values seen in control and this suppression was transient, resulting that the normal level was reached again 19 days after MCA. These results, which conform with the predictions of immunosuppression hypothesis, suggest that MCA inhibits immunological responses including NK activity and thereby allows the outgrowth of antigenic neoplastic cells.

• Journal of Korean Neurosurgical Society
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• 제54권4호
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• pp.302-308
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• 2013

Objective : MR perfusion and single photon emission computerized tomography (SPECT) are well known imaging studies to evaluate hemodynamic change between prior to and following superficial temporal artery (STA)-middle cerebral artery (MCA) anastomosis in moyamoya disease. But their side effects and invasiveness make discomfort to patients. We evaluated the ivy sign on MR fluid attenuated inversion recovery (FLAIR) images in adult patients with moyamoya disease and compared it with result of SPECT and MR perfusion images. Methods : We enrolled twelve patients (thirteen cases) who were diagnosed with moyamoya disease and underwent STA-MCA anastomosis at our medical institution during a period ranging from September of 2010 to December of 2012. The presence of the ivy sign on MR FLAIR images was classified as Negative (0), Minimal (1), and Positive (2). Regions were classified into four territories: the anterior cerebral artery (ACA), the anterior MCA, the posterior MCA and the posterior cerebral artery. Results : Ivy signs on preoperative and postoperative MR FLAIR were improved (8 and 4 in the ACA regions, 13 and 4 in the anterior MCA regions and 19 and 9 in the posterior MCA regions). Like this result, the cerebrovascular reserve (CVR) on SPECT was significantly increased in the sum of CVR in same regions after STA-MCA anastomosis. Conclusion : After STA-MCA anastomosis, ivy signs were decreased in the cerebral hemisphere. As compared with conventional diagnostic modalities such as SPECT and MR perfusion images, the ivy sign on MR FLAIR is considered as a useful indicator in detecting brain hemodynamic changes between preoperatively and postoperatively in adult moyamoya patients.

• 청정기술
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• 제13권3호
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• pp.201-207
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• 2007

본 연구에서는 셀룰로오스계 부직포를 이용하여 상온에서 물에 녹는 카르복시메틸셀룰로오스(carboxymethylcellulose; CMC)를 합성하였다. 실험변수는 반응온도, 시간, 수산화나트륨(NaOH) 및 모노클로로아세트산(monochloroacetic acid; MCA)이다. 머서화(mercerization) 및 에테르화(etherification)할 때, 용해도와 치환도(degree of substitution ; DS)는 NaOH(또는, MCA)농도를 증가시키면서 최대 용해도와 치환도를 관찰하였다. 이때의 최대용해도와 치환도는 NaOH(또는, MCA)농도가 30%일 때 얻어졌다. 치환도를 볼 때, MCA농도의 영향은 NaOH농도에 비해 더 크게 나타났다. CMC섬유의 인장강도(Tensile strength; TS)에서는 효과적인 결과를 보였고, 반응시간, 시약농도와 반응온도에 따라 인장강도는 감소하였다. 그러나 인장강도의 큰 변화가 중성영역 부근에서 관찰되었다.

• Journal of Korean Neurosurgical Society
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• 제42권5호
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• pp.413-415
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• 2007

A 26-year-old man was admitted to our department due to intermittent left hemiparesis for 3 months. Magnetic resonance Image showed subacute infarction in the right precentral gyrus. Digital subtraction angiography and magnetic resonance angiography revealed an aneurysmal protrusion at the right middle cerebral artery (MCA) bifurcation. It was difficult to differentiate the aneurysm from the occlusion of the middle trunk of the MCA trifurcation. Brain single photon emission computerized tomography showed a decrease in perfusion in the right posterior frontal lobe without vascular reserve. Therefore, we planned a superficial temporal artery MCA anastomosis with an exploration of the right MCA bifurcation. Intraoperatively, the aneurysmal opacification on preoperative angiography proved to be the proximal stump of the occluded middle trunk of the MCA trifurcation. An aneurysmal protrusion at the MCA bifurcation does not always indicate an aneurysm. In diagnosing protruding vascular lesions at the MCA bifurcation, the possibility of a vascular stump should be considered according to their angioanatomical appearance and the history of the patient.

• Journal of Magnetics
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• 제16권2호
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• pp.161-163
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• 2011

We report results of first principles calculations for effects of an external electric field (E-field) on the magnetocrystalline anisotropy (MCA) in transition-metal (Fe, Co, and Ni) monolayers and at metal-insulator (Fe/MgO) interfaces by means of full-potential linearized augmented plane wave method. For the monolayers, the MCA in the Fe monolayer (but not in the Co and Ni) is modified by the E-field, and a giant modification is achieved in the $Fe_{0.75}Co_{0.25}$. For the Fe/MgO interfaces, the ideal Fe/MgO interface gives rise to a large out-of plane MCA, and a MCA modification is induced when an E-field is introduced. However, the existence of an interfacial FeO layer between the Fe layer and the MgO substrate may play a key role in demonstrating an Efield-driven MCA switching, i.e., from out-of-plane MCA to in-plane MCA.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.374-375
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• 2006

This paper describes anodic bonding characteristics of MCA to Si-wafer using evaporated Pyrex #7740 glass thin-films for MEMS applications. Pyrex #7740 glass thin-films with the same properties were deposited on MCA under optimum RF sputter conditions (Ar 100 %, input power $1\;W/cm^2$). After annealing at $450^{\circ}C$ for 1 hr, the anodic bonding of MCA to Si-wafer was successfully performed at 600 V, $400^{\circ}C$ in $110^{-6}$ Torr vacuum condition. Then, the MCA/Si bonded interface and fabricated Si diaphragm deflection characteristics were analyzed through the actuation and simulation test. It is possible to control with accurate deflection of Si diaphragm according to its geometries and its maximum non-linearity being 0.05-0.08 %FS. Moreover, any damages or separation of MCNSi bonded interfaces did not occur during actuation test. Therefore, it is expected that anodic bonding technology of MCNSi-wafers could be usefully applied for the fabrication process of high-performance piezoelectric MEMS devices.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.390-391
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• 2006

This paper describes the design, fabrication and characteristics of a micromachined piezoelectric valve utilizing a multilayer ceramic actuator (MCA). The micromachined MCA valve, which uses a buckling effect, consists of three separate structures: the MCA, the valve actuator die and the seat die. The valve seat die with 6 trenches was made, and the actuator die, which is driven by the MCA under optimized conditions, was also fabricated. After Si wafer direct bonding between the seat die and the actuator die, the MCA was also anodically bonded to the seat/actuator die structure. A polydimethylsiloxane (PDMS) sealing pad was fabricated to minimize the leak rate. Finally, the PDMS sealing pad was also bonded to the seat die and the stainless steel package. The MCA valve shows a flow rate of 9.13 sccm at an applied DC voltage of 100 V with a 50% duty cycle and a maximum non-linearity of 2.24% FS. Therefore, the fabricated MCA valve is suitable for a variety of flow control equipment, as a medical bio-system and in the automobile industry.

• 대한핵의학회지
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• 제38권1호
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• pp.62-73
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• 2004

목적: 단순 헤르페스 제 1형 티미딘 키나제(herpes simplex virus type 1 thymidine kinase gene: HSV1-tk)는 GCV와 함께 유전자치료의 한 방법으로서 가장 활발하게 연구되어왔으며, HSV1-tk 효소에 대한 다양한 기질들이 연구되어서 이를 보고 기질로 한 비침습적인 HSV1-tk 유전자 영상시스템에서 가장 널리 사용되고 있다. 본 연구에서는 보고기질로서 방사성 요오드가 표지된 5-iodovinyl-2-deoxyuridine (IVDU) and 5 -iodovinyl-2-fluoro-2-deoxyuridine (IVFRU)를 보고 기질로 하여 HSV1-tk 유전자 영상시스템에서의 유용성을 확인하고자 하였다. 대상 및 방법 HSV1-tk 유전자 영상을 위하여 HSV1-tk 유전자를 레트로 바이러스 벡터를 이용하여 Morris hepatoma 세포주(MCA-tk)에 이입한 세포주를 제조하였으며, HSV1-tk 유전자의 발현을 확인하기 위하여 Northern blotting과 Western Blotting을 시행하였다. 대조세포주인 MCA와 제조된 MCA-tk 세포주에 방사표지 IVDU와 IVFRU를 이용하여 480분까지 세포내 섭취율을 평가하였으며, 또한 MCA-tk 세포주의 백분율을 증가시키면서 이에 따른 IVDU와 IVFRU의 섭취율을 평가함으로서 섭취율과 세포수와의 상관관계를 평가하였다. 결과: MCA-tk 세포주에서 HSV1-tk의 mRNA의 발현과 HSV1-TK 단백질의 발현을 확인하였다. 방사성 요오드 표지 IVDU와 IVFRU 모두는 MCA 세포주에서는 아주 낮은 섭취율을 나타내었으며, MCA-tk 세포주에서는 모두 증가된 섭취를 보였다. IVDU가 480분에서 IVFRU보다 4배 높은 섭취를 나타내었다(p<0.01). 방사표지 IVDU와 IVFRU 모두에서 MCA-tk의 백분율의 증가에 따라서 직선적인 상관관계($R^2>0.96$)를 나타내었다. 결론: 방사성 요오드 표지 IVDU와 IVFRU는 HSV1-tk유전자가 이입된 간암세포주에서 모두 특이적인 높은 섭취율을 나타내고 직선적인 상관관계가 나타나서 두 기질 모두 HSV1-tk유전자 영상시스템에서 보고 기질로서 유용하게 사용될 수 있을것으로 기대된다.