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체결부 및 공차를 고려한 구조물의 확률기반 동적 특성 연구
원준호(Junho Won),강광진(Kwangjin Kang),최주호(Jooho Choi),최재민(Jaemin Choi),전인기(Inki Jun) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
Structural noise is a significant problem in many multi-part or multi-component assemblies. In general, structural noise originates at the location of various fasteners, such as bolts, snap, hinge, weld or other fastener or connector (collectively “fasteners”). Such noise characteristics are almost always undesirable, and for this reason, prediction and prevention of noise source characteristics is important. For the exact prediction of noise source characteristics, a study of the structure’s dynamic characteristics is required. However, the current state of the art does not provide an analytical tool to effectively predict structure’s dynamic characteristics, because consideration of structural uncertainties (i.e. material properties, geometric tolerance, dimensional tolerance, environment and so on) is difficult and very small fasteners in the structure cause a huge amount of analysis time to predict dynamic characteristics using the FEM (finite element method). In this study, to resolve the current state of the art, a new approach is proposed using the FEM and probability analysis. Firstly, equivalent elements are developed using simple element (e.g. bar, beam, mass) to replace fasteners’ finite element model. Developed equivalent elements enable to explain static behavior and dynamic behavior of the structure. Secondly, probability analysis is applied to evaluate the PDF (probability density function) of dynamic characteristics due to tolerance, material properties and so on. MCS (Monte-Carlo simulation) is applied. Proposed methodology offers efficiency of dynamic analysis and reality of the field. Also, proposed methodology becomes basis of noise source prediction. Numerical examples are shown using simple plates joined by fasteners.
원준호(Junho Won),임체규(Che Kyu Lim),이두호(Doo-Ho Lee),최주호(Joo-Ho Choi) 대한기계학회 2012 大韓機械學會論文集A Vol.36 No.12
어셈블리 시스템의 동적거동을 예측하기 위해서는 그 시스템의 체결에 사용된 조인트의 동특성을 정확히 아는 것이 중요하다. 그러나 이들 체결부의 동특성은 매우 큰 산포로 인하여 해석 또는 실험적인 방법으로 동특성을 동정하기 까다로우며, 때로는 불가능 한 경우도 있다. 체결부 동특성 동정 관련 선행 연구사례는 대부분이 실험과 해석을 연계한 방법이며, 그 대상은 볼트조인트에 국한되어 있다. 본 연구에서는 힌지조인트를 대상으로 체결부의 동특성을 동정하는 간단한 방법을 제시한다. 본 연구에서 제시하는 방법의 타당성을 입증하기 위해두 개의 빔이 힌지조인트에 연결된 체결구조물을 제작하여 주파수-응답 실험을 실시하고 그 결과를 제시된 방법의 결과와 비교/검증한다. 그리고 본 연구에서 제안하는 방법을 실제 자동차에 사용되고 있는 글로브박스(Glove Box)의 힌지조인트에 적용해 보았다. The identification of the dynamic properties of structural joints is important for predicting the dynamic behavior of assembled systems. However, the identification of the properties using analytical or experimental approaches is extremely difficult or even impossible. Several studies have proposed hybrid or synthesis methods that simultaneously used analytical and experimental approaches to identify the dynamic properties of a joint. However, among the many types of joints, only the bolt joint was treated as a practical example in these studies. In this study, for a simple assembly system comprising two plates and one hinge joint, a simple methodology involving the use of the static-based subpart analysis method to identify the dynamic properties is proposed. Finally, the proposed method is applied to a glove box in a passenger vehicle that includes hinge joints.
Clinical outcomes of omaliumab treatment on cholinergic urticaria
( Junho Kim ),( Donghyun Kim ),( Young Joo Kim ),( Da Woon Sim ),( Hye Jung Park ),( Kyung Hee Park ),( Jung-won Park ),( Jae-hyun Lee ) 대한내과학회 2015 대한내과학회 추계학술대회 Vol.2015 No.1
Background: Cholinergic urticaria is one of the inducible urticaria and it’s symptoms are provocated by a rise in body temperature. There are some conflicting case reports of omalizumab effect on cholinergic urticaria. Objective: The aim of this study was to evaluate the clinical effect of omalizumab on refractory cholinergic urticaria. Methods: We performed a single center, retrospective study. Since January 2014 to July 2015, 13 patients were treated with omalizumab after failure of antihistamine. Telephone survey including visual analog scale (VAS) and urticaria control test (UCT, 0-16, high score means better control) is performed and response is defined as complete (post treatment VAS≤2 & UCT≥12), partial and no response (post treatment VAS≤2 & UCT≥12). Results: 12 men and 1 women, with a mean age and disease duration of 28 years and 53 months, were included. All patients had at least 5 aggravating factors and 4 patients had chronic spontaneous urticaria and 6 patients had house dust mite sensitization on MAST. After omalizumab, VAS decreased from 8.23±0.93 to 3.69±2.56 (p<0.0001) and UCT increased from 3.77±1.42 to 9.77±3.66 (p> 0.0001) and 5 patients had complete response, while 5 and 3 patients had partial and no response. In responders, the number of injection, injection interval and serum eosinophil count were statistically significant higher than no responders. Conclusions: Our result shows that omalizumab might be useful in refractory cholinergic urticaria. Clinician should consider omalizumab in patients with antihistamine failure.
S-424 Association between critical shear stress and vascular complications in type 2 diabetes
( Junho Lee ),( Hojin Kim ),( Ilrae Park ),( Choonghee Kim ),( Junsung Moon ),( Jisung Yoon ),( Kyuchang Won ),( Hyoungwoo Lee ) 대한내과학회 2016 대한내과학회 추계학술대회 Vol.2016 No.1
The critical shear stress (CSS) is defined as a minimum shear-stress required to disperse RBC aggregates. Increased RBC aggregation is associated with the pathogenesis of vascular disease. The objective of this study was to clarify the association CSS and diabetic microangiopathy. We conducted a cross-sectional study with 234 patients with T2DM who visited Yeungnam university hospital. Patients with end stage renal disease, malignancy and who were diagnosed diabetic ketoacidosis were excluded. CSS was measured with a Rheoscan-D (Rheo-Meditech, Seoul, Korea), a microfluidic hemorheometer. We divided the CSS into quartile (Q1,Q2,Q3, and Q4 from lowest to highest CSS). 209 patients (mean age 59.27±12.64 years, M:F=122:87) were finally included. Patients with microvascular complications had lower CSS compared with patients without any complications (CSS 287 vs. 345, p=0.002). Of them, patients with retinopathy had lower CSS compared with patients without retinopathy (CSS 281 vs. 385, p=0.00), whereas patients with nephropathy and neuropathy had no significant difference in CSS. After adjustment for age, sex, HbA1C, duration of diabetes, hemoglobin, hypertension, smoking, alcohol and lipids, higher CSS remained significantly associated with the prevalence of diabetic nephropathy (Odds ratio for Q1 compared with Q4, 12.329; 95% confidence interval, 1.882-80.775). In patients with T2DM, there were significant relationship between CSS and diabeticnephropathy. These results suggest that CSS could be a novel marker for predicting diabetic nephropathy.