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유동해석을 통한 MR fluid jet polishing 시스템의 재료제거 특성 분석
신봉철,임동욱,이정원 한국금형공학회 2019 한국금형공학회지 Vol.13 No.3
Fluid jet polishing is a method of jetting a fluid to polish a concave or free-form surface. However, the fluid jet method is difficult to form a stable polishing spot because of the lack of concentration. In order to solve this problem, MR fluid jet polishing system using an abrasive mixed with an MR fluid whose viscosity changes according to the intensity of a magnetic field is under study. MR fluid jet polishing is not easy to formulate for precise optimal conditions and material removal due to numerous fluid compositions and process conditions. Therefore, in this paper, quantitative data on the factors that have significant influence on the machining conditions are presented using various simulations and the correlation studies are conducted. In order to verify applicability of the fabricated MR fluid jet polishing system by nozzle diameter, the flow pattern and velocity distribution of MR fluid and polishing slurry of MR fluid jet polishing were analyzed by flow analysis and shear stress due to magnetic field changes was analyzed. The MR fluid of the MR fluid jet polishing and the flow pattern and velocity distribution of the polishing slurry were analyzed according to the nozzle diameter and the effects of nozzle diameter on the polishing effect were discussed. The analysis showed that the maximum shear stress was 0.45 mm at the diameter of 0.5 mm, 0.73 mm at 1.0 mm, and 1.24 mm at 1.5 mm. The cross-sectional shape is symmetrical and smooth W-shape is generated, which is consistent with typical fluid spray polishing result. Therefore, it was confirmed that the high-quality surface polishing process can be stably performed using the developed system.
소뇌출혈을 동반한 혈관아세포종 : 증례 보고 Hemorrhage as an Initial Presentation Case Report
신봉철,박관,민병국,석종식,최덕영 대한신경외과학회 1989 Journal of Korean neurosurgical society Vol.18 No.3
A rare case of a spontaneous intracerebellar hemorrhage from a solid cerebellar hemangioblastoma is reported with review of articles. The cerebellar hemangioblastoma was strongly suspected in the postoperative brain computerized tomography and vertebral angiography. It was successfully removed by second operation and confirmed histologically.
정상 면역능 환자에서 Mucormycosis에 의한 위궤양 1예
신봉철,김형준,우재곤,서은희,허내윤,박종하,김태오 대한내과학회 2011 대한내과학회 추계학술대회 Vol.2011 No.1
Mucormycosis has emerged as an important opportunistic fungall infection in diabetics and other immunocompromised hosts. Rhinosinusitis, pansinusitis, rhino-orbital and rhinocerebral are the common classical manifestations of mucormycosis. However, primary gastrointestinal (GI) mucormycosis is an uncommon disease associated with a high mortality rate. Reported cases of GI mucormycosis in an immunocompetent host are very few in the literature. Standard therapy for invasive mucormycosis includes parenteral amphotericin B (AMB) in combination with radical debridement of infected tissues. We report a 53-year-old man patient with gastric mucormycosis who had only diabetes mellitus and completely recovery after only amphotericin B treatment.
MR Fluid Polishing을 이용한 Co-Cr-Mo alloy의 초정밀 연마 방법
신봉철,김병찬,송기혁,조명우,Shin, Bong-Cheol,Kim, Byung-Chan,Song, Ki-Hyeok,Cho, Myeong-Woo 한국금형공학회 2017 한국금형공학회지 Vol.11 No.3
In general, metallic bio-materials is more widely used in solid tissue like bone or tooth than flexible tissue such as skin or muscle. Especially, Cobalt Chrome Molybdenum(Co-Cr-Mo), which is used in tooth surgery, has a great corrosion resistance. Because this bio-material is non-toxic in human body, and has a bio-compatibility that the vital reaction is not occurred with tissue in body. However the chemical reaction is occurred by fatal matter that deteriorate the property of material surface in conventional polishing, and it can affect to fatal disease in human body or decrease the material properties such as hardness, yield strength or bio-compatibility. This surface in poor condition can cause development of corrosion or bacteria. In this study, MR fluid polishing is used to minimize the scratch, pit or surface flaws generated in conventional polishing. Surface roughness is measured according to the polishing condition to obtain fine surface condition.
신봉철,하석재,강민형,권오양,조명우 한국공작기계학회 2008 한국공작기계학회 추계학술대회논문집 Vol.2008 No.-
In recent, the CFRP(Carbon Fiber Reinforced Plastics) composite has been widely used because it has light-weight and high mechanical strength. Therefore, CFRP composite is applied to variable industrial areas such as aerospace, automobiles, sporting goods, ships and so on. Generally, CFRP composite has been used in the industrial field by mechanical cutting processes. In this research, the CFRP composite specimen are laminated by 64plies with orientation angles such as 0°, 45°, 90° and [0°/±45°/90°]4S. The results are analyzed with cutting force and cutting surface.
신봉철,Sin, Bong-Cheol 한국제품안전협회 2006 제품안전 Vol.2 No.-
"1963년에 설립된 (주)뉴지로는 전기 매트류(Electric Mats)의 발열선 (PVC열선, 실리콘 특수열선) 및 조절기용 케이스와 접속기(Connectors)류 등의 주요 전기 부속품을 제조하는 공장으로 출발하여, 이제 선두기업으로 성장하였습니다. 일관된 정책과 철저한 경영방침으로 목표 달성에 노력하며 그동안의 축적된 노하우와 철두 철미한 관리로 안정된 바탕위에 꾸준한 성장을 거듭해 올 수 있었습니다." 그리고 이제 미래를 향해 웅비를 펼치려 합니다. "철저한 품질관리 시스템과 엄격한 환경 기준에 의한 제조공정으로 신뢰와 믿음을 기초로 앞서가며 항상 미래지향적인 제품을 꾸준히 연구, 개발 하는 노력을 지속적으로 경주 하겠습니다. 설립 당시의 "안전제일", "품질향상", "인화단결" 이라는 사훈의 이념아래 21세기를 이끌어가는 환경친화적이고 미래지향적인 기업이 되겠습니다.
신봉철,정동규,박용석,김영백,민병국,석종식,최덕영 대한신경외과학회 1989 Journal of Korean neurosurgical society Vol.18 No.3
The author analyzed 73 patients with hydrocephalus, who were managed by ventriculoperitoneal shunt in recent 5 years at Chung-Ang University Hospital. The causes of hydrocephalus were brain tumor(23%), head trauma(21%), aqueductal stenosis(16%), myelomeningocele(4%), spontaneous subarachnoid hemorrhage(14%), meningitis(12%) and idiopathic normal pressure hydrocephalus(10%). Their symptoms and signs were gait disturbance(39 patients), mental change(31 patients), papilledema(30 patients) and urinary incontinence(20 patients). Gait disturbance of 39 patients was improved in 23 patients(59%), but visual acuity was improved in only 1 patient. The brain computed tomography showed "roundness" of frontal horns(100%), moderate ventricular dilatation(61%), obliteration of cerebral sulci(68%) and periventricular low densities(56%). Accu-Flo distal slit valve system was applied in all cases and medium pressure valve(closing pressure : 5-9㎝ H₂O) was selected in 65 patients. Twenty reoperations were done in 16 patients and their causes were shunt malfunction(13 cases) and infection(4 cases). Ventricular puncture was done through the Keen's point in all cases and ventricular catheter tip was inserted into the contralateral frontal horn in 30 cases, but there was no shunt malfunction in those patients.
유연한 로봇팔의 선단 위치 제어를 위한 강인한 제어기의 설계
신봉철,이형기,최연욱,안영주 한국융합신호처리학회 2002 융합신호처리학회 논문지 (JISPS) Vol.3 No.2
본 연구는 유연한 로봇팔의 선단 위치를 제어하기 위한 강인한 제어기의 설계하고 이것의 효과를 실험을 통하여 확인하는 데 있다. 이를 위해 먼저 유연한 로봇팔의 모델링을 Lagrange 방정식을 이용하여 수행하여 시스템의 수식모델을 구한 뒤, 이 모델을 기본으로 하는 강인한 제어기의 설계를 LMI(Linear Matrix Inequality)을 적용한 H$_{\infty}$이론을 도입하여 수행한다. 이 과정에서 로봇팔의 선단부하 변경으로 인한 시스템 파라미터의 변동을 플랜트가 가지는 불확실성 영역으로 간주하여 이를 설계에 적극적으로 반영함으로서 결과적으로 플랜트의 파라미터 변동에 강인한 제어기를 구현하고 이것의 유효성을 실험을 통하여 확인한다. .실험을 통하여 확인한다. . The objective of this paper is to design a robust controller for a flexible robot arm manipulator using LMI(Linear Matrix Inequality) theory, and confirm its effectiveness through experimentation. We first describe a modeling Process of the flexible arm in order to get a mathematical model, and then discuss how to approximately obtain the uncertainty of the model for robust control. As to the control system design, we adopt the LMI-based H$_{\infty}$ synthesis algorithm which has the merits of eliminating the regularity restrictions attached to the Riccati-based methods. As a result of this, we can cope with the parameter variation (that is, modeling uncertainty) due to the tip-load variation. Finally we confirm the effectiveness of the controller through experiment and simulation.