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LS-DYNA를 이용한 SUV와 승용차의측면충돌 특성에 대한 연구
임종한 한국인터넷방송통신학회 2018 한국인터넷방송통신학회 논문지 Vol.18 No.2
Since the sides of a vehicle are designed asymmetrically unlike its front or rear, the degree of deformation of the car body greatly differs depending on the site of collision if a broadside collision takes place. When elastic deformation and plastic deformation occur in the car body occur due to a collision, the kinetic energy is absorbed into the body, and the momentum decreases. Generally, an analysis of traffic accidents analyzes the vehicle's behavior after a collision by the law of momentum conservation and corrects the error of the amount of energy absorption due to the deformation of the car body, applying a restitution coefficient. This study interpreted a finite element vehicle model applying the structure of the car body and the material properties of each part with LS-DYNA, analyzed the result and drew the restitution coefficient and the depth of penetration according to the contact area of the vehicle in a broadside collision between an SUV and a passenger car. When the finally calculated restitution coefficient and depth of penetration were applied to the examples of the actual traffic accidents, there was an effect on the improvement of the error in the result. It was found that when the initial input value, drawn using the finite element analysis model, it had a higher reliability of the interpretation than that of the existing analysis techniques. 차량의 측면은 전면이나 후면과 다르게 비대칭으로 설계되어있기 때문에 측면충돌이 일어나는 경우 충돌부위에 따라 차체의 변형정도가 크게 달라진다. 충돌로 인하여 차체에 탄성 및 소성 변형이 일어날 때 운동에너지가 차체로 흡수되어 운동량이 감소하게 된다. 일반적으로 교통사고분석은 충돌 후 차량의 거동을 운동량 보존법칙으로 분석하며 차체의 변형에 따른 에너지 흡수량은 반발계수를 적용해 그 오차를 보정한다. 본 연구에서는 차체의 구조와 각 부품의 재료특성을 적용한 유한요소 차량모델을 LS-DYNA로 해석하였으며, 그 결과를 분석하여 SUV와 승용차의 측면충돌에서 차량의 접촉부위에 따른 반발계수와 충돌감지시간을 도출하였다. 최종적으로 산출된 반발계수와 충돌감지시간을 실제 교통사고 사례에 적용하였을 때 결과오차의 개선효과를 얻었다. 유한요소해석 모델을 이용하여 도출한 초기입력값을 적용했을 때 기존의 분석기법보다 해석의 신뢰도가 높다는 결과를 얻게 되었다.
임종한 대한의사협회 2012 대한의사협회지 Vol.55 No.3
Even in the 21st century, some working environments still expose workers to cement dust. Many people are also exposed to cement dusts particles in their living environment, such as near cement production facilities and areas under construction. The cement industry is involved in the development of the physical infrastructure of advanced industrial society but generates dust during its production. The classic type of pneumoconiosis in coal workers has decreased, but recently, adverse health effects due to exposure to cement dust has increased in cons-truction workers. Cement dust contains fine and ultrafine particles, 0.05-5.0 μm in aerodiameter, which can penetrate into the lung parenchyma and cause toxic damage. Cement dust can cause lung function impairment, chronic obstructive lung disease, pneumoconiosis, and carcinoma of the lungs. Other studies have shown that cement dust may contain toxic heavy metals, such as hexavalent chromium, nickel, and cobalt. Cement dust may cause inflammatory changes in the skin, and often leads to skin diseases or autoimmune diseases. Therefore, close surveillance to monitor the potential toxic effects of cement dust and intervention to minimize its health risks is needed.
인공 태양열에너지를 이용한 방사판 재질에 따른 열전달특성에 관한 연구
임종한,윤준규 한국기계기술학회 2021 한국기계기술학회지 Vol.23 No.3
Solar energy is being constantly studied since it can reduce green house gas by adapting cooling and heating system of domestic architecture as a clean energy source. This study confirmed the reliability of experimental apparatus with temperature measurement of each components by developing cooling and heating system which is combined with artificial solar thermal energy using halogen lamp and refrigerator, examined the heat transfer characteristics according to room internal temperature and lamp distance with the materials of emissive plate (acrylic, copper and stainless). As a result of it, We found that the room internal temperature 18℃ was finer than 21℃ and 24℃ in case of heat transfer rate according to each components. Also, copper in the material change of emissive plate was showed finer heat transfer effects than stainless because of high thermal absorptivity when lamp distance was short.