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송홍기 ( Hong Ki Song ),김관우 ( Kwan Woo Kim ),이석진 ( Seok Jin Lee ),김완종 ( Wan Jong Kim ),조해용 ( Hae Yong Cho ) 충북대학교 산업과학기술연구소 2007 산업과학기술연구 논문집 Vol.21 No.2
Backward extrusion of cup on engine valve has been studied by using finite element method in this thesis. The backward extrusion process was modeled by using Pro/ENGINEER and deformation behavior was analyzed by using rigid-plastic finite element code DEFORM-3D. Through improvement of extrusion process, production cost and period of production can be reduced, also it can help to ensure process stability. In order to reduce extrusion load, the extrusion process simulated by change of preform shape, die and punch shape. Therefore, new extrusion process was designed by using the results of finite element analysis. As results, extrusion load and shear stress were reduced by the shape changes of preform shapes, die shapes and punch shapes. It is useful to improve the extrusion process by using this analysis. And the productivity should be improved by the designed new extrusion process.
안소현,송홍기,김철호,손종희,장민욱,최휘철,Ahn, So Hyun,Song, Hong-ki,Kim, Cheol Ho,Jang, Min Uk,Sohn, Jong-Hee,Choi, Hui Chul 대한임상신경생리학회 2016 Annals of Clinical Neurophysiology Vol.18 No.1
Background: Moyamoya disease is characterized by a progressive stenosis or occlusion of the intracranial internal carotid artery and/or the proximal portion of the anterior cerebral artery and middle cerebral artery. Whether the onset time was childhood or adulthood, the bony carotid canal diameter might be different, but reflects the size of internal carotid artery passing through the bony carotid canal. In this study, we aimed to identify the relationship between bony carotid canal diameter and clinical manifestation. Methods: 146 consecutive patients diagnosed with moyamoya disease by brain imaging studies were included. We measured the diameter of a transverse portion of bony carotid canal on bone window of a brain computed tomography(CT) image. Patients were divided into two groups, ischemic or hemorrhagic stroke according to clinical manifestation. As a result, 115 patients were included. The Suzuki stage was used as criteria for disease progression. Results: Bony carotid canal diameter was $3.6{\pm}0.5$ (right) and $3.6{\pm}0.4$ (left) in the hemorrhagic stroke group, and $3.7{\pm}0.4$ (right) and $3.6{\pm}0.4$ (left) in the ischemic stroke group. The bony carotid canal diameter of the moyamoya vessels (3.6 mm) was smaller than the diameter of non-moyamoya vessels (3.8 mm), significantly (p = 0.042). However, there was no difference in the collateral patterns and clinical manifestation in a comparison of both groups. Conclusions: In our study, there was no significant difference of clinical manifestations and collateral patterns depend on the bony carotid canal diameter in patients with moyamoya disease. These findings suggest that the clinical presentations of moyamoya disease are not related to the onset time of the disease.
금형면에 마찰조건을 달리한 Spline 단조의 유한요소 해석
이석진 ( Seok Jin Lee ),송홍기 ( Hong Ki Song ),김관우 ( Kwan Woo Kim ),김완종 ( Wan Jong Kim ),조해용 ( Hae Yong Cho ) 충북대학교 산업과학기술연구소 2007 산업과학기술연구 논문집 Vol.21 No.2
Forging of trapezoidal spline with solid cylindrical billets has been investigated by using finite element methods in this thesis. spline is widely used by torque transmitter in the fields of automobile, aircraft, and shipping etc. Forging method for spline is cutting or non-cutting in engineering industry and the latter method was considered in this study. Especially, friction on die surface is regarded as the most important factor to improve the dimensional accuracy for complete forming. But prediction of friction factor is very difficult. So, this thesis was focused on the improvement of formability. finite element analysis was carried out to suppress unnecessary burr which is occurred in gap between the die and the punch. after that time, the results were examined with comparison of analysis and experiment to verify new forging process for spline. result of simulation and experiment by same condition has been correspond.
기질성 뇌증후군에서 Oxiracetam의 임상적 효과에 대한 이중맹검 대조연구
이병철(Byung Chul Lee),권기한(Ki Han Kwon),김상윤(Sang Yun Kim),송홍기(Hong Ki Song),김성민(Sung Min Kim),유경호(Kyung Ho Yoo),이현미(Hyun Mi Lee),강경수(Kyung Soo Kang),윤여훈(Yeo Hun Yoon) 대한약학회 1993 약학회지 Vol.37 No.5
Previous experimental and clinical investigations suggest a possible role of new nootropic drug, oxiracetam, in improving cognitive performances in patients affected by organic brain syndrome. In this study, that cognitive and behavioral effects of oxiracetam treatment in patients with clinical symptoms of organic brain syndrome were evaluated. Sixty-six patients were enrolled and assigned to either oxiracetam or placebo, according to a randomized, double-blind design between two patient-groups. Either oxiracetam or placebo was orally given bid for 8 weeks ; daily dose of oxiracetam was 1600mg. All the patients, enrolled in this study, were diagnosed as having mild to moderate cognitive dysfunction as defined by a baseline Mini Mental State Examination Korean version (MMSE-K) score between 14 and 25. The patients underwent, at baseline, 4 weeks and 8 weeks after, routine laboratory study (CBC, SMA12, U/A, EKG) and the following neuropsychological tests ; MMSE-K, modified Korean Wechsler Intelligence Scale(MKWIS), Nurses'' Observation Scale for Geriatric patients(NOSGER). Fifteen patients of whom were dropped out or excluded from the analysis because of poor compliance or violation of the protocol. Fiftyone patients (aged 54~78 years, male 25, female 26) were analyzed (vascular dementia, 30 ; senile dementia of Alzheimer type, 9 ; mixed type, 5 ; other cause, 7). Statistical analysis of the data demonstrated that the two groups were comparable at baseline. At the end of each study period the oxiracetam group scored significantly better on the majority of the tests evaluating cognitive function, psychometricity and the improvement rating scale of subjective symptoms than placebo group, in which worsening trends or no changes were seen on the whole. No side effects were noted during oxiracetam treatment. The present study, showing positive clinical findings after oxiracetam therapy, confirmed that this drug can be useful pharmacological treatment in organic brain syndrome.
이인환(In-Hwan Lee),조해용(Hae-yong Cho),송홍기(Hong-ki Song),김지훈(Ji-Hoon Kim),서보혁(Bo-Hyuck Seo),경기현(Ki-Hyun Kyoung) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
Forging for spring cup of engine valve was investigated in this study. New method is needed to reduce cost and development lead time required to fix forming process of new product , that eventually can provide die, metal flow and forming loads with high confidence level. FEM could provide required detail information that could reduce trial error in advance before the actual production. By using the rigid-plastic finite element simulation, possibilities of improving former research were explored. Results generated by FEM could foresee expected material deformation in advance and made possible new forming process successfully.