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고장력강판 적용을 위한 자동차 범퍼빔 구조성능의 기초연구
강종수(Jong-Su Kang),송명환(Myung-Hwan Song),임재용(Jae-Yong Lim) 한국산학기술학회 2017 한국산학기술학회논문지 Vol.18 No.6
최근 자동차 업계는 연비향상 및 안전성 강화를 위해 경량 신소재를 적용하여 부품의 경량화를 추구하고 있다. 이를 위해 차체 부품 소재로서 고장력강판의 적용 비중이 50%를 넘고 있는 실정이다. 이에, 본 논문에서는 범퍼빔 부품의 소재로 고장력강판 적용을 위한 기초 연구로서 소재 및 두께 변경에 따른 범퍼빔의 구조강성과 에너지 흡수능력을 해석적 방법으로 비교 평가하였다. 우선 고장력강판을 범퍼빔에 적용하기 위해 기존의 범퍼빔 단면형상과는 다른 타입의 범퍼빔 단면형상을 설계하였으며, 굽힘해석을 통해 설계된 범퍼빔이 충분한 구조성능, 즉, 구조강성과 굽힘하중력을 가지고 있는지 조사하였다. 중앙접합부의 형상에 따라 굽힘에 대한 구조성능은 현저한 차이가 관찰되지는 않았으며, 25ton, 7.5ton/㎜내외의 충분한 굽힘저항력과 강성을 가지고 있는 것으로 조사된다. 또한, 충돌해석을 통해 소재 및 두께를 변경하였을 경우의 효과를 비교평가하였다. 해석결과 고장력강판을 범퍼빔에 적용하기 위해서는 두께를 줄임으로써 기존소재에 버금가는 에너지흡수성능을 구현할 수 있으며, 동시에 뚜렷한 경량화를 이룰 수 있을 것으로 판단된다. 본 기초연구를 토대로 고장력강판 범퍼빔의 구조성능 개선을 위한 향후 연구방향에 대해 제시하였다. Consistent efforts have been made to reduce the weight of automotive parts by using lightweight materials. This has resulted in the replacement of conventional steels in car body structures with high-strength steels, and the current usage rate has reached 50%. This study examines the structural stiffness and energy absorption capability of bumper beams made of high-strength steels. New types of bumper beam cross sections are proposed.The structural stiffness and maximum bending force were computed via finite element analysis as about 25tons and 7.5tons/㎜, and there were no significant differences among the proposedcross sections. Dynamic analysis was also carried out to investigate the energy absorption capabilities of the bumper beams, and the effects of materials and thickness reduction were analyzed. High-strength steel can be used to achieve weight reduction with comparable structural performance to conventional bumper beams.
국군수도병원 입원환자의 재활치료 분석 연구 : 현황 및 역할을 중심으로
김경은 ( Kyoung-eun Kim ),김은진 ( Eun Jin Kim ),송명환 ( Myung-hwan Song ),김운희 ( Un-hui Kim ),최송이 ( Song-yi Choi ) 국군의무사령부 2023 대한군진의학학술지 Vol.54 No.1
Objective The role of rehabilitative therapy is important in military hospitals. However, an analysis of the distribution of injury sites and disease conditions that necessitate rehabilitative therapy in military hospitals has not been conducted yet. We aimed to identify the characteristics of inpatients who underwent rehabilitative therapy at the Armed Forces Capital Hospital (AFCH) and to discuss the role of rehabilitative therapy in AFCH. Method A comprehensive investigation was conducted on the record of one-on-one allocated exercise therapy and occupational therapy of 2022 for inpatients at the AFCH and the patients’ demographic data and medical data were investigated. Results In 2022, a total of 1,236 individuals (1,207 males and 29 females) underwent 20,943 sessions of rehabilitative therapy during their hospital admission. Joint-related musculoskeletal issues comprised 92.7% of the admissions, with ankle and knee problem being the most prevalent. Brain injuries accounted for only 2.6% of the cases but constituted 15.3% of the total therapy sessions. Patients with neuromuscular disorders or other conditions showed a significantly longer hospitalization period (p<.001) and a significantly higher frequency of exercise or occupational therapy (p=.004) compared to those with musculoskeletal disorders affecting joint areas. Conclusion In the AFCH, large number of the inpatients who received rehabilitation therapy were musculoskeletal patients. The Rehabilitation Department of AFCH is responsible for acute and subacute rehabilitation, and it is essential to apply appropriate treatments according to the severity of functional impairments.
인정제,신용승,김헌영,김재우,송명환,박진수 한국공작기계학회 2000 한국공작기계학회 추계학술대회논문집 Vol.2000 No.-
The contact forces between die components for the drawing of large size automotive panels introduce elastic deflections of the die components. Due to the deflections, the gap between blank holder and die varies locally resulting in nonuniform material flow. Such a nonuniform die gap usually requires correcting operation, so called die spotting, which is time consuming trial and error process. To reduce the die spotting time, the optimization of the blank holder bending deflection is needed. In this paper, we implemented an analysis procedure to predict the blank holder deflection. The analysis procedure and design of experiments techniques are applied to the optimization of balance block heights. The optimization results can be used as guidelines in actual die spotting process.