• Applied Microscopy
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• 제31권2호
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• pp.117-128
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• 2001

DMF는 특별히 PVA에 대해 수소결합 등의 강한 상호작용을 하는 용매가 아니다. 오히려 UCST계로서 온도가 낮아질수록 상분리나 phase demixing을 일으킨다. PVA/DMF의 겔화는 x-ray 회절이나 열분석을 통해 crystallization-induced gelation으로 밝혀졌다. 그리고 겔화 온도가 낮을수록 결정화는 빠르게 진행되었다. 소량의 PEG는 PVA/DMF 겔 형성을 도왔으며 urea는 겔 형성을 방해하였다. 전자현미경은 이 겔화 과정을 잘 보여 주었다. 갓 만들어진 젤은 표면에 깊은 주름이 있으며 아직 상분리가 본격적으로 시작되기 전의 상태로서 아주 미세한 DMF가 차지하는 공간인 구멍들이 사진에 포착되지 않는다. Aging시간이 길어지면서 상분리가 시작되면 표면의 분화구가 나타나기 시작하며, 이 분화구는 원래 용매상이 차지하고 있던 공간으로서 phase demixing에 의해 PVA chain들은 분화구 주변으로 분리된다. 상분리과정에서 PVA chain들은 서로 당겨져서 표면적이 줄어듬과 동시에 분화구 크기도 커진다. Aging에 따른 x-ray결과와 열적 성질은 이 모든 과정을 뒷받침한다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제36권3호
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• pp.103-110
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• 2014

Purpose: The current gold standard for clinical jawbone formation involves autogenous bone as a graft material. In addition, demineralized dentin can be an effective graft material. Although demineralized dentin readily induces heterotopic bone formation, conventional decalcification takes three to five days, so, immediate bone grafting after extraction is impossible. This study evaluated the effect of vacuum ultrasonic power on the demineralization and processing of autogenous tooth material and documented the clinical results of rapidly processed autogenous demineralized dentin (ADD) in an alveolar defects patient. Methods: The method involves the demineralization of extracted teeth with detached soft tissues and pulp in 0.6 N HCl for 90 minutes using a heat controlled vacuum-ultrasonic accelerator. The characteristics of processed teeth were evaluated by scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Bone grafting using ADD was performed for narrow ridges augmentation in the mandibular area. Results: The new processing method was completed within two hours regardless of form (powder or block). EDS and SEM uniformly demineralized autotooth biomaterial. After six months, bone remodeling was observed in augmented sites and histological examination showed that ADD particles were well united with new bone. No unusual complications were encountered. Conclusion: This study demonstrates the possibility of preparing autogenous tooth graft materials within two hours, allowing immediate one-day grafting after extraction.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제49권1호
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• pp.43-48
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• 2023

The biocompatibility and durability of implant fixtures are major concerns for dentists and patients. Mechanical complications of the implant include abutment screw loosening, screw fracture, loss of implant prostheses, and implant fracture. This case report aims to describe management of a case of fixture damage that occurred after screw fracture in a tissue level, internal connection implant and microscopic evaluation of the fractured fixture. A trephine bur was used to remove the fixture, and the socket was grafted using allogeneic bone material. The failed implant was examined by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), which revealed a fractured fixture with both normal and irregular bone patterns. The SEM and EDS results give an enlightenment of the failed fixture surface micromorphology with microfracture and contaminated chemical compositions. Noticeably, the significantly high level of gold (Au) on the implant surface and the trace amounts of Au and titanium (Ti) in the bone tissue were recorded, which might have resulted from instability and micro-movement of the implant-abutment connection over an extended period of time. Further study with larger number of patient and different types of implants is needed for further conclusion.

• Applied Microscopy
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• 제45권3호
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• pp.177-182
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• 2015

The boiler tubes of X20CrMoV12.1 used in fossil-fired power plants were obtained and analyzed for the effect of water treatment on the steam corrosion-induced oxide scale in an effort to better understand the oxide formation mechanism, as well as pertinent method of maintenance and lifetime extension. The specimens were analyzed using various microscopy and microanalysis techniques, with focuses on the effect of water treatment on the characters of scale. X-ray diffraction analysis showed that the scales of specimens were composed of hematite ($Fe_2O_3$), magnetite ($Fe_3O_4$), and chromite ($FeCr_2O_4$). Electron backscatter diffraction analysis showed that the oxides were present in the following order on the matrix: outer $Fe_2O_3$, intermediate $Fe_3O_4$, and inner $FeCr_2O_4$. After all volatile treatment or oxygenated treatment, a dense protective $Fe_2O_3$ layer was formed on the $Fe_3O_4$ layer of the specimen, retarding further progression of corrosion.

• Journal of the Korean Wood Science and Technology
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• 제34권3호
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• pp.1-7
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• 2006

국내에서 재배된 케나프의 해부 물리적 특성을 광학현미경, 주사전자현미경 및 X선회절법으로 조사하였다. 그 결과 케나프는 사부에 인피섬유, 사부 방사조직, 피층 유세포, 사관요소 등이 존재하였고, 목부는 도관요소, 목섬유, 방사조직 등으로 구성되어 있었다. 관공은 고립 및 2~3개가 방사방향으로 복합한 것이 많이 존재하였고, 방사조직은 평복, 방형, 직립세포가 모두 분포하고 있었다. 수피부의 인피섬유 길이는 생장기간이 길어짐에 따라 점차 증가하였고, 목부 섬유의 길이는 평균 0.74~0.82 mm로써 생장기간과 줄기의 높이에 관계없이 거의 차이가 없었다. 상대결정화도는 사부가 53~74%, 목부가 43~58%인 것으로 나타났으며, 셀룰로오스의 결정폭은 사부가 2.68~3.24 nm, 목부가 2.46~2.95 nm 정도인 것으로 나타났다. 케나프 줄기의 높이가 증가함에 따라 생재함수율과 생재밀도는 증가하였으나, 기본밀도는 낮게 나타났다.

• 한국광학회:학술대회논문집
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• 한국광학회 2005년도 제16회 정기총회 및 동계학술발표회
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• pp.350-351
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• 2005

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.429-429
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• 2000

Micro positioning mechanism is the key technology in many fields, such as scanning electron microscopy (SEM), x-ray lithography, mask alignment and micro-machining. In the paper, a 3DOF parallel-type micro-positioning mechanism is proposed. This mechanism uses piezo-actuators and Flexure hinge to control x, y and $\theta$ motion. It is shown both analytically and numerically that 2 DOF flexure hinge model was better precision than 1 DOF flexure hinge design.

• 대한화학회지
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• 제60권1호
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• pp.93-98
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• 2016

• 한국자기학회지
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• 제19권4호
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• pp.121-125
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• 2009

비정질 $Ge_{1-x}Mn_x$ 박막을 $400^{\circ}C$에서 $700^{\circ}C$까지 온도범위에서 각 3분씩 고진공챔버($10^{-8}$ torr)에서 열처리하였고, as-grown 시료와 열처리한 시료의 전기적 특성과 자기수송특성을 연구하였다. 성분함량은 energy dispersive X-ray spectroscopy(EDS)와 x-ray photoelectron spectroscopy(XPS)로 측정하였으며, 박막의 구조분석은 x-ray diffractometer(XRD)와 transmission electron microscopy(TEM)를 이용하였다. 자성특성은 여러 범위의 자기장에서 Magnetic property measure system(MPMS)를 이용하였다. 박막의 전기적 특성은 standard four-point probe와 Physical property measurement system(PPMS)로 측정하였으며, van der Pauw 방법을 사용하여 Anomalous Hall effect를 측정하였다. X-ray 회절 패턴 분석을 통해 $500^{\circ}C$에서 3분 동안 열처리한 시료는 여전히 비정질 상태인 것을 알 수 있었으며, $600^{\circ}C$의 열처리 온도에서 결정화를 확인할 수 있었다. as-grown $Ge_1$_$_xMn_x$ 박막과 열처리한 $Ge_{1-x}Mn_x$ 박막을 온도에 따른 비저항 값의 변화를 측정하였고, 반도체의 특성을 보이는 것을 확인할 수 있었다. 또한 열처리 온도가 높을수록 비저항도 증가하는 것을 관찰할 수 있었다. $700^{\circ}C$에서 열처리한 $Ge_1$_$_xMn_x$ 박막은 저온에서 negative magnetoresistance(MR)을 확인할 수 있었고, MR ratio는 10 K에서 약 8.5 %를 보였다. 모든 MR 그래프에서 curve의 비대칭을 확인 할 수 있었으며, anomalous Hall Effect는 약하지만 250 K까지 관측이 되었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.286-287
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• 2012

Reset-first resistive switching mechanism based on reduction reaction in HfO2-x with oxygen drift-diffusion was studied. we first report that the indirect evidence of local filamentary conductive path formation in bulk HfO2 film with local TiOx region at Ti top electrode formed during forming process and presence of anion-migration at interface between electrode and HfO2 during resistive switching through high resolution transmission electron microscopy (HRTEM), electron disperse x-ray (EDX), and electron energy loss spectroscopy (EELS) mapping. Based on forming process mechanism, we expected that redox reaction from Ti/HfO2 to TiOx/HfO2-x was responsible for an increase of initial current with increasing the post-annealing process. First-reset resistive switching in above $350^{\circ}C$ annealed Ti/HfO2 film was exhibited and the redox phenomenon from Ti/HfO2 to TiOx/HfO2-x was observed with high angle annular dark field (HAADF) - scanning transmission electron microscopy (STEM), EDX and x-ray photoelectron spectroscopy. Therefore, we demonstrated that the migration of oxygen ions at interface region under external electrical bias contributed to bipolar resistive switching behavior.