적색발광 Y(V_0.5,P_0.5)O₄:Eu 나노형광체의 수열 합성 및 투명 플라즈마 디스플레이 소자 제작으로의 응용

송우석,양희선,Song, Woo-Seuk,Yang, Hee-Sun 한국세라믹학회 2011 한국세라믹학회지 Vol.48 No.1

Transparent plasma display can be realized by developing the synthetic chemistry of appropriate nanophosphors and generating nanophosphor-based transparent luminescent layers. For this goal, red-emitting $Y(V_{0.5},\;P_{0.5})O_4$:Eu nanophosphors were synthesized by a facile hydrothermal route at $200^{\circ}C$ for 48 h and the resulting nanophosphors were subsequently annealed at $800^{\circ}C$ at an ambient atmosphere. The crystallographic structure, morphology, and emission property of the as-synthesized and annealed nanophosphors were compared. Choosing 2-methoxyethanol as a dispersion medium and applying a standard sonication, well-dispersed nanophosphor solutions could be prepared. Using these dispersions, visible transparent nanophosphor layers were spin-deposited on glass substrates. By combining $Y(V_{0.5},\;P_{0.5})O_4$:Eu nanophosphor layer/glass substrate as a rear plate with a front plate used in a conventional plasma display panels (PDPs), mini-sized transparent red-emitting PDPs were constructed. Transmittance and luminance properties of two transparent test panels using as-synthesized versus $800^{\circ}C$-annealed nanophosphors were characterized and compared.

무치악 구개결손 환자를 위한 폐쇄장치의 삼차원 유한요소 분석

송우석,김명주,임영준,권호범,Song, Woo-Seok,Kim, Myung-Joo,Lim, Young-Jun,Kwon, Ho-Beom 대한치과보철학회 2011 대한치과보철학회지 Vol.49 No.3

연구 목적: 이 연구의 목적은 삼차원 유한요소 분석법을 이용하여 무치악 구개결손 환자에 사용되는 폐쇄장치의 응력 및 변위를 측정하고 이를 총의치 모형과 비교하는 것이다. 연구 재료 및 방법: 무치악 환자의 컴퓨터단층촬영 영상을 기반으로 구개 중앙에 상악절제술 후 발생한 결손부를 가지는 무치악 상악모형과, 무치악 3차원 유한요소 모형을 제작하였다. 각각의 모형에 적합한 총의치와 폐쇄장치를 제작하고 좌측 소구치와 구치 부위에 200 N의 수직하중을 가하였다. 3차원 유한요소 분석법을 이용하여 두 모형에서 보철물과 잔존 상악골조직의 von Mises 응력값과 변위량을 측정하였다. 결과: 두 모형 모두 하중을 가한 쪽의 피질골에서 최대 von Mises 응력 값이 관찰되었다. 총의치 모형의 피질골에서 가장 높은 값은 2.73 MPa 이었으며 폐쇄장치 모형의 피질골에서 가장 높은 값은 2.69 MPa 이었다. 보철물의 조직면에서도 높은 응력값이 관찰되었다. 최대 변위량은 폐쇄장치에서 총의치보다 더 높은 값이 관찰되었다. 결론: 폐쇄장치는 총의치에 비해 교합력 전달 면에서 불리했고, 더 큰 변위량이 관찰되어 상악절제술을 받은 무치악 환자의 보철치료 시 해부학적 지식에 바탕을 둔 정확한 인상채득과 보철치료 원칙의 적용이 고려되어야 한다. Purpose: The purposes of this study were to evaluate the stress distributions and the displacements of obturator for edentulous maxillectomy patients and to compare them with those of complete denture using three-dimensional finite element analysis. Materials and methods: Based on the CT image of edentulous patient, three-dimensional finite element model of edentulous maxillae was constructed. Three-dimensional finite element model of edentulous maxillae with palatal defect was also fabricated. On each model, complete denture and obturator prosthesis were created. Vertical static force of 200 N was applied on the left maxillary premolar and molar region. The von Mises stress values and the displacements of models were analyzed using three-dimensional finite element analysis. Results: Maximum von Mises stress values were recorded in the cortical bones of both models. The von Mises stress value in the complete denture model was 2.73 MPa and 2.69 MPa in the obturator model. High von Mises stress values were also observed on the tissue surface of prosthesis. The maximum value of the displacement in the obturator was higher than that of complete denture. Conclusion: The obturator showed a worse result in terms of stress distribution and displacement than complete denture. In the prosthodontic rehabilitation of edentulous maxillectomy patient accurate impression procedure based on patients'anatomy and application of prosthodontic principle should be considered.

제 1족지에 발생한 섬유골성 가종양: 1예 보고

송우석,최준철,김학수,한은미,Song, Woo-Suk,Choi, Joon-Cheol,Kim, Hak-Soo,Han, Eun-Mee 대한근골격종양학회 2010 대한골관절종양학회지 Vol.16 No.2

섬유골성 가종양(fibro-ossous pseudotumor)은 빠르게 성장하면서 동통을 유발하는 매우 드문 양성 병변이다. 이 병변은 악성으로 오인되기도 하지만 국소절제술만으로 치료가 되는 비침습형 질환으로, 주로 수부에 발생한다. 제 1족지 원위 지골의 종물과 동통으로 내원한 20세 여자 환자에서 발생한 섬유골성 가종양 1예를 경험하여 문헌 고찰과 함께 보고하는 바이다. Fibro-osseous pseudotumor is an extremely rare benign lesion which is fast-growing and painful. It is often misdiagnosed as a malignancy, but it is a noninvasive entity and can be cured by simple resection. We report a case of fibro-osseous pseudotumor of the distal phalanx of great toe in 20-year-old female patient who present with painful mass.

적층구조 촉매층(Al/Fe/Al)을 이용한 탄소나노튜브의 합성에서 최상층 알루미늄 층의 역할

송우석,최원철,전철호,류동헌,이승엽,신용숙,박종윤,Song, W.,Choi, W.C.,Jeon, C.,Ryu, D.H.,Lee, S.Y.,Shin, Y.S.,Park, C.Y. 한국진공학회 2007 Applied Science and Convergence Technology Vol.16 No.5

적층구조 촉매층(Al/Fe/Al)을 이용하여 열 화학기상증착(thermal chemical vapor deposition ; TCVD)법을 통해 탄소 나노튜브를(carbon nanotubes ; CNTs)를 합성하였다. Raman spectroscopy, SEM 및 HR-TEM 분석결과, G/D는 22.7이며, 직경이 $1.14\;{\sim}\;1.32\;nm$인 금속성의 단일벽 탄소 나노튜브(single-walled CNTs ; SWCNTs)의 다발(bundle)들이 기판 전체에 network 구조로 형성되어 있는 것을 확인할 수 있었다. 이는 최상층의 Al이 촉매인 Fe의 응집현상(agglomeration)을 막아주는 역할을 하여 작고 균일한 핵 생성 사이트(nucleation site)를 통해 좁은 직경분포를 가진 단일벽 탄소 나노튜브가 합성되었음을 알 수 있다. In this study, we report the synthesis of the single-walled carbon nanotubes(SWCNTs) using laminated catalyst(Al/Fe/Al) layer deposited by sputter on Si(001). SWCNTs are grown by thermal chemical vapor deposition (TCVD) method. As the results of scanning electron microscopy(SEM), high resolution transmission electron microscopy(HR-TEM) and Raman spectroscopy, we confirmed the SWCNTs bundles with narrow diameter distribution of $1.14{\sim}1.32\;nm$ and average G&D ratio of 22.76. Compare to the sample having Fe/Al catalyst layer, it can be proposed that the top-aluminum incorporated with iron catalyst plays an important role in growing process of CNTs as a agglomeration barrier of the Fe catalyst. Thus, we suggest that a proper quantity of aluminium metal incorporated in Fe catalyst induce small and uniform iron catalysts causing SWCNTs with narrow diameter distribution.

구형 SiO₂@Y₂O₃: Eu 코어-쉘 복합체 형광체 합성 및 특성

송우석,양희선,Song, Woo-Seuk,Yang, Hee-Sun 한국세라믹학회 2011 한국세라믹학회지 Vol.48 No.5

The monodisperse spherical $SiO_2$ particles were overcoated with $Y_2O_3:Eu^{3+}$ phosphor layers via a Pechini sol-gel process and the resulting $SiO_2@Y_2O_3:Eu^{3+}$ core-shell phosphors were subsequently annealed at $800^{\circ}C$ at an ambient atmosphere. The crystallographic structure, morphology, and luminescent property of core-shell structured $SiO_2@Y_2O_3:Eu^{3+}$ phosphors were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and photoluminescence (PL). The spherical, nonagglomerated $SiO_2$ particles prepared by a Stober method exhibited a relatively narrow size distribution in the range of 260-300 nm. The thickness of phosphor shell layer in the core-shell particles can be facilely controlled by varying the coating number of $Y_2O_3:Eu^{3+}$ phosphors. The core-shell structured $SiO_2@Y_2O_3:Eu^{3+}$ phosphors showed a strong red emission, which was dominated by the $^5D_0-^7F_2$ transition (610 nm) of $Eu^{3+}$ ion under the ultraviolet excitation (263 nm). The PL emission properties of $SiO_2@Y_2O_3:Eu^{3+}$ phosphors were also compared with pure $Y_2O_3:Eu^{3+}$ nanophosphors.

구연산의 적용시간에 따른 임플란트 표면변화에 대한 주사전자현미경적 연구

송우석,권영혁,이만섭,박준봉,허익,Song, Woo-Seok,Kwon, Young-Hyuk,Lee, Man-Sup,Park, Joon-Bong,Herr, Yeek 대한치주과학회 2002 Journal of Periodontal & Implant Science Vol.32 No.4

The present study was performed to evaluate the effect of citric acid on the change of implant surface microstructure according to application time. Implants with pure titanium machined surface, titanium plasma-sprayed surface, and sand-blasted, large grit, acid etched surface were utilized. Implant surface was rubbed with pH 1 citric acid for $\frac{1}{2}$ min., 1 min., 1 $\frac{1}{2}$ min., 2 min., and 3min, respeaively in the test group and implant surface was not treated in the control group. Then, the specimens were processed for scanning electron microscopic observation. The following results were obtained. 1. Both test and control group showed a few shallow grooves and ridges in pure titanium machined surface implants. There were not significant differences between two groups. 2. In titanium plasma-sprayed surfaces, round or amorphous particles were deposited irregularly. The irregularity of titanium plasma-sprayed surfaces conditioned with pH 1 citric acid was lessened and the cracks were increased relative to the application time of pH 1 citric acid. 3. Sand-blasted, large grit, acid etched surfaces showed the macro/micro double roughness. The application of pH 1 citric acid didn't change the characteristics of the sand-blasted, large grit, acid etched surfaces. In conclusion, the application of pH 1 citric acid to titanium plasma-sprayed surface is improper. And pure titanium machined surface implants and sand-blasted, large grit, acid etched surface implants can he treated with pH 1 citric acid for peri-implantitis treatment if the detoxification of these surfaces could be evaluated.

케로신의 온도가 화학 발광에 미치는 동적 특성

송우석(Wooseok Song),김도헌(Dohun Kim),구자예(Jaye Koo) 한국추진공학회 2015 한국추진공학회 학술대회논문집 Vol.2015 No.11

무밸브 시스템과 다중 튜브를 이용한 펄스데토네이션 연소기

송우석(Wooseok Song),손민(Min Son),Kanmaniaja Radhakishnan,유기정(Kijeong Yu),구자예(Jaye Koo) 한국추진공학회 2015 한국추진공학회 학술대회논문집 Vol.2015 No.5

자동차 Cooling Fan용 비등각 축류홴 소음해석

송우석(W.-S. Song),이정수(J.-S. Lee),김주용(J.-Y. Kim),이승배(S. Lee) 한국유체기계학회 2004 유체기계 연구개발 발표회 논문집 Vol.- No.-

The 2-dimensional unsteady flows on and around the cambered airfoils were computed by applying LES with the deductive dynamic SGS model. The unsteady flow field were used as inputs to compute the far-field sounds and directivity patterns from rotating blades by a hybrid approach that exploits Farassat's formula. The BEM (Boundary Element Method) was applied to predict the frequency characteristics from the rotating blades for the cases of even- and uneven-pitched fans. The BEM results suggested that the unevenly pitched fan have less pronounced discrete peaks at BEF frequencies, which was confirmed by the experiment.

고해상도 단영상에서의 그림자 추출기법 비교

송우석(Woo-seok Song),변영기(Young-gi Byun),김용민(Yong-min Kim),유기윤(Ki yun Yu) 대한공간정보학회 2007 한국지형공간정보학회 학술대회 Vol.2007 No.6

위성영상 기술의 발달과 고해상도 위성영상의 해상도 규제가 완화됨에 따라 건물의 높이 정보를 획득하는데 있어 고해상도 위성영상의 그림자 정보를 이용하는 연구들이 활발히 수행되어지고 있다. 그림자 정보를 이용하여 건물 높이 정보를 획득하는 연구의 정확도를 높이기 위해서는 정확한 건물의 그림자 탐지가 선행되어야 한다. 따라서 본 논문에서는 단영상을 이용한 그림자 탐지기법인 임계값법(Thresholding), 영상분류법, 영역확장법(Region Growing)을 건물의 그림자 탐지에 적용하여 각 기법의 장단점과 정확도를 평가하였다. 영상에서 수동으로 건물의 그림자를 디지타이징한 참조 자료와 기법들을 적용하여 탐지한 결과 영상을 시각적으로 비교하였고, 오차행렬(Confusion Matrix)을 이용한 전체정확도(Accuracy), F-measure, AOR(Area Overlap Ratio)을 이용하여 정량적인 정확도평가를 수행하였다. 실험결과 영역확장법을 적용한 경우 시각적ㆍ정량적으로 가장 높은 정확도를 보였으며, 영상분류법을 적용한 경우 시각적으로는 임계값을 적용한 경우보다 좋은 결과를 보였으나 정량적으로는 가장 낮은 정확도를 보였다.