• 대한치과교정학회지
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• 제4권1호
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• pp.57-61
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• 1974

The patient, a girl of 19 years in good health, had a class I malocclusion. The maxillary left centra1 incisors and both lateral incisors had already erupted. But the space for the right central incisor was partially closed by the mesial drifting of the neighboring teeth. The caused a shift in the midline and a cross-bite relation on the incisors. X-ray examination revealed the presence of the right central incisor in the alveolar bone and odontoma just above the crown of the right central incisor. After enough space for the impacted incisor was created in the dental arch with a open-coil spring the rectangular incision was made. Removing the odontoma uncovered the flat surface of the labial aspect of the incisor. During the tooth had erupted of its own accord, any unnecessary force had been imposed on the tooth. When it was decided that the tooth should be brought out by the mechanical device, the gold cast onlay with hook was used and run a light elastic between this hook and the main arch wire. Finally the tooth was brought down to the arch level. The result was excellent. Fortunately the esthetic problem and any detrimental effects on the psychological make-up could be avoided.

• 천문학회보
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• 제41권1호
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• pp.68.4-69
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• 2016

We report preliminary results of KaVA observations of central galaxies in cool-core and non cool-core clusters. The main goal is to study how cooling environments of galaxy clusters affect the central AGN activities especially at its innermost region. For KaVA observations, 7 radio bright AGNs have been selected from the extended Highest Flux Galaxy Cluster Sample (eHIFLUGCS; the X-ray flux limited & all sky galaxy cluster catalog) with various cooling timescales. In our previous KVN study, we have found that most AGNs in the cool-core clusters show the hint of pc-scale jet-like features while the ones in the non cool-core clusters do not. Using the KaVA 22/43 GHz data of a much higher resolution than the KVN resolution, we have investigated detailed pc-scale jet properties such as physical size, morphology, and radiative age. Based on the KaVA data, we discuss the effect of cluster cooling environment on the evolution of AGNs in the cluster center.

• Geomechanics and Engineering
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• 제35권6호
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• pp.627-636
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• 2023

The essence of subgrade mud pumping under train load is the migration of fine particles in subgrade soil. The migration of fine particles will change the pore structure of overlying ballast, thus affecting the mechanical properties and hydraulic properties of ballast layer. It is of great theoretical significance and engineering value to study the effect of fine particle migration on the pore structure of ballast layer under cyclic loading. In this paper, a tailor-made subgrade mud pumping test model and an X-ray computed tomography (CT) scanning equipment were used to study the influence of migration of fine particles in subgrade soil on the pore parameters (plane porosity, volume porosity, pore distribution and pore connectivity) of overlying ballast under cyclic loading. The results show that the compression of ballast pores and the blockage of migrated fine particles make the porosity of ballast layer decreases gradually. And the percentage of small pores in ballast layer increases, while the percentage of large pores decreases; the connectivity of pores also gradually decreases. Based on the test results, an empirical model of ballast porosity evolution under cyclic loading is established and verified.

• Advances in materials Research
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• 제1권2호
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• pp.115-128
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• 2012

The structural and electrical properties of $(1-x)Ba(Sm_{1/2}Nb_{1/2})O_3-xBaTiO_3$; ($0{\leq}x{\leq}1$) ceramics were prepared by conventional ceramic technique at $1375^{\circ}C$/7 h in air atmosphere. The crystal symmetry, space group and unit cell dimensions were derived from the X-ray diffraction (XRD) data using FullProf software whereas crystallite size and lattice strain were estimated from Williamson-Hall approach. XRD analysis of the compound indicated the formation of a single-phase cubic structure with the space group Pm m. Dielectric study revealed that the compound $0.75Ba(Sm_{1/2}Nb_{1/2})O_3-0.25BaTiO_3$ is having low and ${\varepsilon}^{\prime}$ and ${\varepsilon}^{{\prime}{\prime}}$ a low $T_{CC}$ (< 5%) in the working temperature range (up to+$100^{\circ}C$) which makes this composition suitable for capacitor application and may be designated as 'Stable Low-K' Class I material as per the specifications of the Electronic Industries Association. The correlated barrier hopping model was employed to successfully explain the mechanism of charge transport in the system. The ac conductivity data were used to evaluate the density of states at Fermi level, minimum hopping length and apparent activation energy of the compounds.

• 대한화학회지
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• 제55권3호
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• pp.436-443
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• 2011

o-phenylenediamine, 3-acetyl-6-methyl-(2H)pyran,2,4(3H)-dione (dehydroacetic acid 또는 DHA) 및 2, 4-dihydroxy benzaldehyde에서 비롯된 4-hydroxy-3-(1-{2-(2,4-dihydroxy-benzylidene)-amino phenylimino}-ethyl)-6-methyl-pyran-2-one ($H_2$L)의 La(III), Ce(III), Pr(III), Nd(III), Sm(III) 및 Gd(III) 고체착물을 합성하여 원소분석, 전도도법, 자기수자율, UV-vis, FT-IR, 1H-NMR, X-선 회절, 열분석으로 특성을 규명하였으며, 항미생물 활성도를 조사하였다. FT-IR 스펙트럼 결과에 의하면 이 리간드는 중심금속에 대해 ONNO 주개원자를 통해 이염기성 사배위 리간드로 행동함을 알 수 있다. 원소분석 결과로부터 이들 착물의 화학량론비는 1:1 (금속: 리간드)임을 알 수 있다. 물리 및 화학적 실험결과로부터 La(III), Ce(III), Pr(III), Nd(III), Sm(III) 및 Gd(III) 착물은 일그러진 팔면체의 기하구조를 가짐을 알 수 있다. X-선 회절 데이터로부터 La(III) 및 Ce(III) 착물은 단사정계, 그리고 Pr(III) 및 Nd(III) 착물은 사방정계를 가짐을 알 수 있다. 이들 착물의 열적 행동(TG/DTA)을 연구하였으며, 속도론적 파라메타를 Horowitz-Metzger 및 Coats-Redfern 방법으로 결정하였다. 리간드와 그 착물의 항박테리아 활성도를 Staphylococcus aureus, Escherichia coli 및 Bacillus Sp.에 대해, 그리고 살균활성도를 Aspergillus Niger, Trichoderma 및 Fusarium oxysporum에 대해 각각 조사하였다.

• 대한화학회지
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• 제53권4호
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• pp.407-414
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• 2009

o-phenylenediamine, 3-acetyl-6-methyl-(2H) pyran, 2,4 (3H)-dione (dehydroacetic acid or DHA) 및 살리실 알데히드로부터 유도한 4-hydroxy-3-(1-{2-(2-hydroxy-benzylidene)-amino phenylimino}-ethyl)-6- methy-pyran-2-one (H2L) 의 Cu(II), Ni(II), Co(II), Mn(II) 및 Fe(III) 고체 착물을 합성한 후, 원소분석, 전도 도법, 수자율, 자외선-가시선, 적외선, $^1H$-NMR 스펙트라, X-선 회절, 열분석을 통해 특성을 규명하고 항균 활성을 조사하였다. IR 스펙트럼 데이터로부터 이 리간드가 중심 금속이온에 대해 ONNO 주개원자 배열을 갖는 이염기성 네자리 리간드로 행동함을 제안하였다. 원소분석 데이터로부터 이들 착물의 화학량론이 1:1 (금속:리간드)임을 알았다. 물리-화학적 데이타로부터 Cu(II) 및 Ni(II) 착물이 사각평면 기 하구조, 그리고 Co(II), Mn(II) 및 Fe(III) 착물이 팔면체 기하구조임을 제안하였다. X-선 회절 데이터로 부터 Cu(II) 착물이 사방정계(orthorhombic) 결정계, Ni(II), Co(II) 및 Fe(III) 착물이 단사계(monoclinic) 결정계 그리고 Mn(II) 착물이 정방정계(tetragonal) 결정계임을 제안하였다. 착물의 열적 행동(TG/DTA) 을 연구하였으며 Coats-Redfern 방법으로 반응속도 파라메터를 결정하였다. 리간드와 이들 금속 착물을 이용하여 Staphylococcus aureus 및 Escherichia coli에 대한 향균 활성과 Aspergillus Niger 및 Trichoderma 에 대한 살균 활성을 조사하였다.

• Journal of Electrochemical Science and Technology
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• 제14권4호
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• pp.377-387
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• 2023

Ni-W/Al₂O₃ nano-composites were electrodeposited on mild steel substrate for mechanical and corrosion resistance applications. This study focused on the preparation of Ni-W/Al₂O₃ nano-composite coating with various quantity of Al₂O₃ incorporations. The addition of Al₂O₃ in the electrolytes were varied from 1-10 g/L in electrolytes and the Al₂O₃ incorporation in Ni-W/Al₂O₃ nano-composite coatings were obtained from 1.82 to 13.86 wt.%. The incorporation of Al₂O₃ in Ni-W alloy matrix influenced the grain size, surface morphology and structural properties were observed. The distributions of Al₂O₃ particle in alloy matrix were confirmed using electron microscopy (FESEM and TEM) and EDAX mapping analysis. The crystal structure informations were studied using X-ray diffraction method and it confirms that the deposits having cubic crystal structure. The better corrosion rate (0.87 mpy) and microhardness (965 HV) properties were obtained for the Ni-W/Al₂O₃ nano-composite coating with 13.86 wt.% of Al₂O₃ incorporations.

• 한국광학회지
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• 제6권3호
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• pp.188-200
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• 1995

파장 13nm의 연 X-선을 사용하여 초고밀도 반도체 칩을 네작할 수 있는 고분해능의 투사 결상용 2-반사경계(배율=1)을 설계하였다. 등배율(1:1)의 광학계는 holosymmetric system으로 구성하였을 때 코마와 왜곡수차가 완전히 제거되는 이점을 갖는다. 2-반사경 holosymmetric system에서 추가적으로 구면수차를 제거하기 위해 두 반사경을 동일한 포물면으로 만들고 두 반사경 사이 거리를 조절하여 비점수차와 Petzval 합이 상쇄되게 함으로써 상면만곡 수차를 보정하였다. 이렇게 구한 aplanat flat-field 포물면 2-반사경 holosymmetric system은 크기가 작고 광축회전대칭의 간단한 구조를 가지면 중앙부 차폐가 아주 작다는 특징을 갖고 있다. 이 반사경계에 대해 잔류 수차, spot diagrams, 회절효과가 고려된 NTF의 분석 등을 통해 연 X-선 리소그라피용 투사 광학계로서의 성능이 조사된 결과, $0.25\mum$및. $0.18\mum$의 해상도가 얻어지는 상의 최대 크기가 각각 4.0mm, 2.5mm로 구해졌고 초점심도는 각각 $2.5.\mu$m, $2.4.\mum$로 얻어졌다. 그러므로 이 반사경계는 256Mega DRAM 및 1Giga DRAM의 반도체 칩 제작의 연구에 응용될 수 있다.

• 한국지구과학회지
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• 제29권7호
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• pp.579-585
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• 2008

열적으로 불안정한 강착원반의 비선형 유체역학적 모형에 기초하여 블랙홀 마이크로케이사의 광폭발 한계 순환주기에 대한 원반 질량의 시간적 진화 모형을 계산하였다. 블랙홀의 질량, 원반 크기 및 질량 유입률과 같은 물리적인 매개변수들은 블랙홀 X선 신성의 원형인 A0620-00에서 관측된 역사적인 1975 광폭발을 재현하도록 선택되었다. 중심부에서 원반으로 쪼여지는 조사(照射)의 시간에 따른 효과는 직접 조사와 원반위의 뜨거운 강착 흐름으로부터 굴절되어 원반에 쪼여지는 간접조사의 두 가지 방법이 고려되었다. 우리의 강착원반 열적 불안정성 모형은 광폭발의 순환과정 전반에 걸쳐 X-선 변광체들에서 관측된 광도의 전형적인 복사 광도를 설명할 수 있다. 강착원반의 최대질량 ${\sim}4.03{\times}10^{24}g$은 광폭발의 점화 때에 얻어지며, 최소질량 ${\sim}8.54{\times}10^{23}g$은 차가운 쇠퇴기와 정지기(靜止期) 때에 이루어진다. 원반의 질량은 광폭발 한계 순환주기에 걸쳐 약 5배 정도 변한다.

• Restorative Dentistry and Endodontics
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• 제45권2호
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• pp.11.1-11.9
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• 2020

Objectives: This study compared the flow and filling of several retrograde filling materials using new different test models. Materials and Methods: Glass plates were manufactured with a central cavity and 4 grooves in the horizontal and vertical directions. Grooves with the dimensions used in the previous study (1 × 1 × 2 mm; length, width, and height respectively) were compared with grooves measuring 1 × 1 × 1 and 1 × 2 × 1 mm. Biodentine, intermediate restorative material (IRM), and mineral trioxide aggregate (MTA) were evaluated. Each material was placed in the central cavity, and then another glass plate and a metal weight were placed over the cement. The glass plate/material set was scanned using micro-computed tomography. Flow was calculated by linear measurements in the grooves. Central filling was calculated in the central cavity (㎣) and lateral filling was measured up to 2 mm from the central cavity. Results: Biodentine presented the least flow and better filling than IRM when evaluated in the 1 × 1 × 2 model. In a comparison of the test models, MTA had the most flow in the 1 × 1 × 2 model. All materials had lower lateral filling when the 1 × 1 × 2 model was used. Conclusions: Flow and filling were affected by the size of the test models. Higher grooves and materials with greater flow resulted in lower filling capacity. The test model measuring 1 × 1 × 2 mm showed a better ability to differentiate among the materials.