• Wind and Structures
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• 제34권1호
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• pp.59-72
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• 2022

In this work the numerical results of the flow around a 5:1 rectangular cylinder at Reynolds numbers 3 000 and 40 000, zero angle of attack and smooth incoming flow condition are presented. Implicit Large Eddy Simulations (ILES) have been performed with a high-order accurate spatial scheme and an implicit high-order accurate time integration method. The spatial approximation is based on a discontinuous Galerkin (dG) method, while the time integration exploits a linearly-implicit Rosenbrock-type Runge-Kutta scheme. The aim of this work is to show the feasibility of high-fidelity flow simulations with a moderate number of DOFs and large time step sizes. Moreover, the effect of different parameters, i.e., dimension of the computational domain, mesh type, grid resolution, boundary conditions, time step size and polynomial approximation, on the results accuracy is investigated. Our best dG result at Re=3 000 perfectly agrees with a reference DNS obtained using Nek5000 and about 40 times more degrees of freedom. The Re=40 000 computations, which are strongly under-resolved, show a reasonable correspondence with the experimental data of Mannini et al. (2017) and the LES of Zhang and Xu (2020).

• 농업과학연구
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• 제9권2호
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• pp.519-539
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• 1982

1981년(年) 5월(月) 중순(中旬)부터 9월(月) 중순(中旬)까지 충남(忠南) 대덕군(大德郡), 공주군(公州郡), 논산군(論山郡)에 걸쳐 위치(位置)한 계룡산(鷄龍山)에 분포(分布)하는 곤충상(昆蟲相)을 조사(調査)한 결과(結果) 다음과 같은 결과(結果)를 얻었다. 1. 총(總) 20목(目) 156과(科) 548속(屬) 673종(種)의 곤충(昆蟲)이 동정확인(同定確認)되었다. 2. 한국미기록종(韓國未記錄種)으로서 16종(種)이 발견(發見) 되었는데 검은촉각베짱이, 구마모도대벌레, 르위스집게벌레, 물가장님노린재, 왕잎벌레, 별수염치레하늘소, 멧누에나방붙이, 흰띠자나방, 큰애기자나방, 연갈색잎말이나방, 빗줄애수염나방, 오끼나와오색나비, 큰알락각다귀, 이시끼광대파리, 쑥광대파리, 여덟점맵시벌등이었으며 이들의 한국명은 모두 새로이 명칭한 것이다. 3. 이들 16종(種)의 한국미기록종중(韓國未記錄種中) 별수염치레하늘소, 오끼나와오색나비등은 남방계통(南方系統)의 곤충(昆蟲)으로서 이외에도 돌좀, 뱀허물쌍살벌, 청줄벌, 줄점팔랑나비, 사향제비나비, 극남노랑나비, 대만흰나비, 남방부전나비, 청띠신선나비, 제주왕나비등의 상당히 많은 종류(種類)의 아열대성(亞熱帶性) 남방계통곤충(南方系統昆蟲)들이 혼서(混棲)하고 있었다.

• Journal of Korean Neurosurgical Society
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• 제30권6호
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• pp.688-698
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• 2001

Objectives : Parkinson's disease is a well-known neurodegenerative disease characterized by dopaminergic cell death in the substantia nigra. The reactive gliosis by activated astrocytes and microglias is no more regarded as a simple sequel of neuronal cell death. Microglial activation takes place in a stereotypic pattern with graded morphologic and functional(resting, activated and phagocytic) changes. In Parkinson's disease animal model, the degree of microglial activation along the nigro-striatal dopaminergic tract has not been studied intensively. The purpose of this study was to elucidate the characteristics of microglial reaction and to grade its degree of activation at substantia nigra and corpus striatum using 6-hydroxydopamine induced rat model of Parkinson's disease. Methods : Using Sprague-Dawley rat, parkinsonian model was made by 6-hydroxydopamine(OHDA) induced destruction of medial and lateral substantia nigra(SN). The rat was sacrificed 3-, 5-, 7-, 14- and 21-day-after operation. For control group, we injected saline with same manner and sacrificed 3-day after operation. With immunohistochemistry, we examined dopaminergic neuronal cells and microglial expression using tyrosine hydroxylase (TH) and OX-42 antibodies, respectively. Also we performed in situ hybridization for osteopontin, a possible marker of subset in activated microglia. Results : 1) In lesioned side of substantia nigra and corpus striatum, the TH immunoreactivity was markedly decreased in whole experimental groups. 2) Using optical densitometry, microglia induced immunoreactivity of OX-42 was counted at SN and corpus striatum. At SN, it was increased significantly on the lesioned side in control and all time-dependent experimental groups. At striatum, it was increased significantly in post lesion 3-day group only(p <0.05). Compared to control group, immunoreactivity of OX-42 on lesioned side was increased in groups, except post lesion 21-day group, at SN. Only post lesion 3-day group showed significance at striatum(p <0.05). Compared to SN region, immunoreactivity of OX-42 was much weaker in striatum. 3) Microscopically, the microglias showed typically different activation pattern. At SN, numerous phagocytic microglias were found at pars compacta and reticularis of lesion side. At striatum, no phagocytic form was found and the intensity of staining was much weaker. 4) At SN, the immunoreactivity of osteopontin showed definite laterality and it was markedly increased at pars compacta of lesion side with relatively short duration time. At striatum, however, it was not detected by in situ hybridization technique. Conclusion : The nigral 6-OHDA induced rat model of Parkinson's disease revealed several characteristic patterns of microglial reaction. At SN, microglias was activated shortly after direct neuronal damage and maintained for about three weeks. In contrast, despite of sufficient dopaminergic insufficiency at striatum, activation of microglias was trivial, and distinguished 3 day later. Antegrade slow neuronal degeneration is major pathophysiology in striatal dopaminergic deficiency. So, the acuteness of neuronal damage and consequential degree of neuronal degeneration may be important factor for microglial activation in neurodegenerative diseases such as Parkinson's disease. Additionally, osteopontin may be a possible marker for several subsets of activated microglia, possibly the phagocytic form.