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Seongjin Jeon,Ji-Yun Park,Jong-min Lee,Seulgi Hong 대한평형의학회 2022 Research in Vestibular Science Vol.21 No.2
We report a unique case of vertebrobasilar transient ischemic attacks manifesting as isolated, recurrent, orthostatic dizziness with posterior inferior cerebellar artery (PICA) stenosis. A 57-year-old male patient without past medical history, pre-sented with brief orthostatic dizziness for 2 weeks. There was no associated nausea, vomiting, diplopia, or weakness. On neuro-otologic examination, the pa-tient did not show spontaneous, positional, or gaze-evoked nystagmus. Vestibular function tests such as caloric test, head impulse test, video-oculography, and tilt table test were normal. Brain diffusion-weighted images showed multiple small high signal intensities in the bilateral cerebellar hemispheres. Brain magnetic re-sonance angiography revealed hypoplasia of the right vertebral artery without fo-cal intracranial focal stenosis. Four-vessel cerebral angiogram showed severe stenosis at the right PICA artery. Our patient’s clinical scenario appears unique hemo-dynamic spells without symptoms or signs of posterior circulation ischemia. Phy-sicians should also consider cerebrovascular ischemic when the patient suffers repeated orthostatic dizziness that is not explained clinically.
Jeon, Seungyeon,Hong, Seongjin,Kwon, Bong-Oh,Park, Jinsoon,Song, Sung Joon,Giesy, John P.,Khim, Jong Seong Pergamon Press 2017 Chemosphere Vol.168 No.-
<P><B>Abstract</B></P> <P>The west coast of Korea has experienced environmental deterioration for more than half a century. In the present study, we specifically aimed to: i) evaluate potential toxicities of contaminants in sediments that cause effects mediated through the aryl hydrocarbon receptor (AhR) and estrogen receptor (ER); ii) determine spatio-temporal distributions of polycyclic aromatic hydrocarbons (PAHs) and alkylphenols (APs); and iii) identify causes of greater potencies of samples. From 2010 to 2014, sediments were collected from 12 major estuarine and coastal regions along the west coast of South Korea. <I>In vitro</I> cell bioassays were performed to determine AhR- and ER-mediated potencies using H4IIE-<I>luc</I> and MVLN cells, respectively. Fifteen PAHs and six APs in sediments were identified by GC/MSD. Results of bioassays generally showed a low-to-moderate degree of contamination, however, greater AhR- and ER-mediated potencies were measured at some locations. Concentrations of PAHs and APs varied among locations, which indicated that sources were independently affected by the surrounding environment (e.g., industrial complex and cities). Results of bioassays were generally well correlated with concentrations of putative causative chemicals. Benzo[<I>k</I>]fluoranthene, dibenz[<I>a</I>,<I>h</I>]anthracene, and benzo[<I>b</I>]fluoranthene were the major AhR agonists, explaining approximately 30% of the bioassay-derived benzo[<I>a</I>]pyrene equivalent concentration (BaP-EQ). Unknown AhR and ER agonists and potential mixture effects remain in question. Overall, the present study provides baseline information on chemical contaminations and potential toxicity of sediments in a fairly wide geographical region of the west coast of South Korea.</P> <P><B>Highlights</B></P> <P> <UL> <LI> AhR and ER potencies in sediments from the west coast of Korea were characterized. </LI> <LI> Bioassay results generally showed a low-to-moderate contamination of sediments. </LI> <LI> Distributions of PAHs and APs were generally affected by human activities. </LI> <LI> Five- and six-ring PAHs were the major AhR-active compounds in sediments. </LI> <LI> Known and unknown aromatics with log K<SUB>ow</SUB> 5–8 are likely major AhR agonists. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
CFD-DEM 연계기법을 활용한 고정식 해양구조물의 모노파일 주위 유동 및 세굴해석
송성진(Seongjin Song),전우영(Wooyoung Jeon),박선호(Sunho Park) 한국해양공학회 2019 韓國海洋工學會誌 Vol.33 No.3
When an offshore foundation is exposed to waves and currents, local scour could develop around a pile and even lead to structural failure. Therefore, understanding and predicting the scour due to sediment transport around foundations are important in the engineering design. In this study, the flow and scour around a monopole foundation exposed to a current were investigated using a method that coupled the computational fluid dynamics (CFD) and discrete element method (DEM). The open source computation fluid dynamics library OpenFOAM and a sediment transport library were coupled in the OpenFOAM platform. The incipient motion of the particle was validated. The flow fields and sediment transport around the monopole were simulated. The scour depth development was simulated and compared with existing experimental data. For the upstream scour hole, the equilibrium scour depth could be reproduced qualitatively, and it was underestimated by about 23%.
선행 차량의 후진에 의한 저속 충돌 시 탑승자 경추 상해에 대한 연구
김성진(Seongjin Kim),전우정(Woojung Jeon),박우식(Woosik Park),서영일(Youngil Seo),손권(Kwon Son) 한국자동차공학회 2013 한국 자동차공학회논문집 Vol.21 No.3
This study assesses neck injury of occupants in a real traffic accident case that a preceding vehicle moved backward and impacted a parked vehicle at a low velocity. This case is different from a case of whiplash injury caused by rear impact on vehicle. The impact velocity was estimated from damages of the two vehicle bumpers and the displacement of the parked vehicle was also estimated from CCTV images. MADYMO simulation was performed based on the vehicle specifications and investigation report. The comparison of neck flexion moments with the corresponding injury criteria revealed that occupants of the parked vehicle might have hardly neck injury.
Influence of Refractive Indices of Glass Matrix on the Reflectance of Glass Composites
Jaeseung Jeon,Jungki Lee,Seongjin Hwang,Jihwan Ahn,Hyungsun Kim 대한금속·재료학회 2011 METALS AND MATERIALS International Vol.17 No.4
To understand the optical behavior of glass matrix composites, the species of glass matrix and ceramic filler,the mixing ratio, the refractive index of the components and the interaction between the matrix and the filler should be considered simultaneously. Two kinds of glass matrix with different refractive index (n = 1.50 and 1.69) and absorption coefficient were mixed with calcite (n = 1.59) in various volume percentages and their optical behavior, such as reflectance and scattering coefficient was studied after firing. The reflectance and the scattering coefficient increased with increasing calcite content regardless of the optical characteristics of the glass matrix. The reflectance of the composite was strongly correlated with the absorption coefficient of the glass matrix while the scattering coefficient of the composite was highly dependent on the refractive index of the glass matrix. We suggest that using the matrix with a higher refractive index than that of the filler may improve the reflectance of the glass composite.
능동 안티롤바와 ESP를 이용한 차량 전복 방지 제어기 설계
임성진(Seongjin Yim),전광기(Kwangki Jeon),이경수(Kyongsu Yi) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
This paper presents a method to design a controller for rollover prevention using active anti-roll bar and electronic stability program (ESP). ESP itself has the capability to prevent rollover to some extent since active braking could reduce the vehicle speed and the lateral acceleration. However, ESP cannot prevent rollover under severe maneuvering conditions. To enhance the rollover prevention capability of ESP, an active anti-roll bar is adopted. A controller for an active anti-roll bar is designed with linear quadratic static output feedback control methodology to attenuate the effect of the lateral acceleration on the roll angle and the roll rate through controlling the suspension stroke and the tire deflection of vehicles. Although this active anti-roll bar shows a remarkable performance in the ride comfort and the rollover prevention, it has a drawback in the loss of maneuverability. Under this situation, ESP can give a synergetic effect on the rollover prevention and the maneuverability. Through simulations, the proposed method is shown to be effective in preventing the rollover.