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현동호,임현경,박지원,김종림,이하영,박순찬,안중호,백정환,최충곤,이정현 대한자기공명의과학회 2012 Investigative Magnetic Resonance Imaging Vol.16 No.1
Purpose : To compare the enhancement pattern of normal facial nerves on 3D-FLAIR and 3D-T1-FFE-F) sequences at 3.0 T MR units. Materials and Methods: We assessed 20 consecutive subjects without a history of facial nerve abnormalities who underwent temporal bone MRI with contrast enhancement between January 2008 and March 2009. Two neuroradiologists independently reviewed pre-/post-enhanced 3D-T1-FFE-FS and 3D-FLAIR images respectively with 2-week interval to assess the enhancement of normal facial nerves divided into five anatomical segments. The degree of enhancement in each segment was graded as none, mild or strong, and the results of 3D-FLAIR and 3D-T1-FFE-FS image sets were compared. Results: On 3D-FLAIR images, one of the two reviewers observed mild enhancement of the genu segment in two (10%) subjects. On 3D-T1-FFE-FS images, at least one segment of the facial nerve was enhanced in 13 (65%) subjects. At least one reviewer found that 17 of the 100 segments showed enhancement on 3D-T1-FFE-FS images, with the mastoid segment being the most commonly enhanced. Interobserver agreement on 3D-T1-FFE-FS images was good for enhancement of the normal facial nerve (κ= 0.589). Conclusion: In contrast to 3D-T1-FFE-FS, normal facial nerve segments rarely showed enhancement on 3D-FLAIR images.
SiO<sub>2</sub>-TiO<sub>2</sub>계 복합 나노섬유의 제조 및 광활성 연구
현동호,임태호,이성욱,Hyun, Dong Ho,Lim, Tae-Ho,Lee, Sung Wook 한국공업화학회 2008 공업화학 Vol.19 No.5
$(1-x)SiO_2-(x)TiO_2$ composite fibers with various compositions of $TiO_2$ were prepared by electrospinning their sol-gel precursors of titanium (IV) iso-propoxide (TiP), and tetraethyl orthosilicate (TEOS). The surface morphology and structure of sintered composite fibers were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), simultaneous thermogravimetric analysis-differential scanning calorimetry (TGA-DSC) and Fourier transform infrared spectroscopy (FT-IR). As the content of $TiO_2$ in $(1-x)SiO_2-(x)TiO_2$ system was increased the average diameter of composite fibers was proportionally increased. Also, the transformation of $TiO_2$ from anatase to rutile form was inhibited by the highly dispersed $TiO_2$ around $SiO_2$ particles up to $0.6SiO_2-0.4TiO_2$ composite fibers even after calcination at $1000^{\circ}C$. The photocatalytic activity of $SiO_2-TiO_2$ composite fibers was examined for the methylene blue (MB) decomposition which was confirmed using UV-vis/DRS spectra. The experiments demonstrated that the MB in aqueous solution was successfully photodegraded using $SiO_2-TiO_2$ composite nanofibers under UV-visible light irradiation.
전기방사법에 의한 $SiO_2$-$TiO_2$계 복합무기섬유의 제조 및 광촉매 활성 평가
현동호,김상범,이승구,정원양,김진호,이성욱,Hyun, Dong-Ho,Kim, Sang-Beom,Lee, Seung-Goo,Chung, Won-Yang,Kim, Jin-Ho,Lee, Sung-Wook 한국섬유공학회 2009 한국섬유공학회지 Vol.46 No.5
A series of $SiO_2$-$TiO_2$ composite sols have been prepared by the hydrolysis of tetraethyl orthosilicate (TEOS) and titanium (IV) isopropoxide dissolved in isopropanol which was controlled by HCl addition. The maximum amount of $TiO_2$ for suitable fiber formation was about 50 mol% in $SiO_2$-$TiO_2$ composite inorganic fibers. The SEM, TEM, and FT-IR results showed that the surface morphology and crystalline phase of the electro spun composite micro/nanoscale $SiO_2$-$TiO_2$ fibers were strongly affected by the content of $TiO_2$ and calcination temperature. The SEM and TEM images reveal that the fibers had diameters varying from hundreds of nanometer to 2 micrometer. The photocatalytic activity of composite inorganic fibers was evaluated by decomposition of methylene blue, acetaldehyde, and formaldehyde in waste water which are recognized as volatile organic compounds (VOCs).
레이저 표면 딤플 패턴된 PMMA 소재 표면의 식염수 윤활 하에서의 미끄럼 마찰특성
현동호,채영훈,정다이 한국트라이볼로지학회 2023 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.39 No.4
Laser surface dimple patterning is a method of laser surface texturing to reduce lubrication sliding friction. The dimple pattern improves friction properties by reserving lubricant and trapping worn particles. This surface texturing technology can reduce coefficients of friction and extend the service life by applying a uniform load to the surface of the material. This study investigates the friction properties using PMMA, a highly compatible polymer material, as a specimen. We observe the friction properties of untextured specimens by processing specimens with dimple pattern densities of 5 and 10 on the surface area using laser. Dimple pattern density affects the coefficient of friction. We present the following friction property results using a pin-on-disc sliding friction test under saline lubrication. The coefficients of friction for the dimple patterned specimens are lower than those for the untextured specimens. As the normal load and sliding speed increase, the coefficients of friction of the dimple pattern specimens decrease differently from those of the untextured specimens. The specimen with a dimple pattern density of 5 at a normal load of 24.5 N and a sliding speed of 0.22 m/s has the best friction properties. Notably, different friction properties are exhibited depending on the dimple pattern densities.
현동호,채은진,서준범,강준원,도경현,이충욱,이현주,황혜전,임태환 대한영상의학회 2010 대한영상의학회지 Vol.63 No.4
The preoperative evaluation of the hemodynamics associated with PAPVR and rheumatic mitral valve stenosis is necessary for successful surgical treatment, even though the incidence rate is rare. The purpose of this case report is to present the usefulness of CT and MRI for diagnosing rheumatic mitral stenosis and partial anomalous pulmonary venous connection to the left innominate vein accompanied by the presence of the levoatriocardinal vein and evaluating its flow dynamics.
현동호,박광보,조성기,박홍석,신성욱,주성욱,도영수,주인욱,최동욱 대한영상의학회 2017 Korean Journal of Radiology Vol.18 No.5
Objective: The study aimed to describe portal stenting for postoperative portal occlusion with delayed (≥ 3 months) variceal bleeding in the afferent jejunal loop. Materials and Methods: Eleven consecutive patients (age range, 2–79 years; eight men and three women) who underwent portal stenting between April 2009 and December 2015 were included in the study. Preoperative medical history and the postoperative clinical course were reviewed. Characteristics of portal occlusion and details of procedures were also investigated. Technical success, treatment efficacy (defined as disappearance of jejunal varix on follow-up CT), and clinical success were analyzed. Primary stent patency rate was plotted using the Kaplan-Meier method. Results: All patients underwent hepatobiliary-pancreatic cancer surgery except two children with liver transplantation for biliary atresia. Portal occlusion was caused by benign postoperative change (n = 6) and local tumor recurrence (n = 5). Variceal bleeding occurred at 27 months (4 to 72 months) and portal stenting was performed at 37 months (4 to 121 months), on average, postoperatively. Technical success, treatment efficacy, and clinical success rates were 90.9, 100, and 81.8%, respectively. The primary patency rate of portal stent was 88.9% during the mean follow-up period of 9 months. Neither procedure-related complication nor mortality occurred. Conclusion: Interventional portal stenting is an effective treatment for delayed jejunal variceal bleeding due to portal occlusion after hepatobiliary-pancreatic surgery.
계절변화를 설명하는 초등학교 6학년 학생들의 대안개념 연구
현동호 ( Hyun Dong-ho ),양경은 ( Kyonng-eun Yang ) 한국교원대학교 과학교육연구소 2016 청람과학교육연구논총 Vol.22 No.2
This study has the premise that Lakatos research program having concepts of the core that scientists strongly maintain in the science theory development and the protection area that protects the core is similar to student`s structure of alternative concept. Therefore, the study is conducted under the assumption that the core of Lakatos research program and the core of alternative concept of students are similar. And to research the structure of alternative concept, the center theory, the firm core, the additional theory, the guard protecting the core and the basic theory of Lakatos research program known as a natural phenomenon are used and the experimentation to change the alternative concept by proposing discording circumstances is imported. The following conclusion is made based on results of the research. The reason for students having difficulties in the optics area that performs the decisive roles for students to understand the astronomical phenomenon is their insufficiencies for understanding on the relation among celestial bodies in large scale rather than their insufficient specific knowledge. Students see the Sun that transmits lights spread to all directions and hit the Earth as a lamp, not as a celestial body. Also, on the item suggested to check the background knowledge on the seasonal change, students select the oval orbit more than any others. This is because students support the lamp theory and the distance theory mostly as the cause of seasonal change. Such knowledge is the recognition formed by experiences in younger years of students. Such firm cores interfere formations of scientific concepts leanrned in classes. Also, the tendency explaining the seasonal change with changes of the length of daytime and the meridian transit altitude by the tilted axis of the Earth without weakening the distance theory after a class through textbook. Such transition concept connected to scientific concept is confirmed also in the phase having suspicion gradually on the own belief. It shows that one concept is not completely disappeared and replaced by other concept and remains in any formation.