• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
• /
• pp.2135-2146
• /
• 2011

The rail surface irregularity is generated severely by train braking effect in the section of station. The braking force increases slip rate and friction factors caused by wheel-rail contact points. It brings rail surface irregularity as well. In this study, interactions between wheel and rail were investigated using rolling contact fatigue theory and mechanism of rail degradation through fracture mechanics. For the more, the Von-Mises stress occurred on the rail due to the interaction between wheel and rail was analyzed using 3-D finite element method. The amounts of surface irregularity of rail were measured according to accumulated passing tonnage in urban railway in fields. Therefore, the maintenance of rail should be separated by running and braking sections to prevent RCF defects.

• Composites Research
• /
• 제28권4호
• /
• pp.168-175
• /
• 2015

탄소섬유 강화 복합재료는 높은 비강도 및 비강성을 가지기 때문에 자동차 산업, 선박, 우주 항공 산업과 같은 다양한 산업 분야에 적용되어 왔으며, 수요가 점차 증가하고 있다. 탄소섬유 강화 복합재료에는 기지재로 주로 에폭시(Epoxy)와 같이 점도가 낮고 젖음 특성이 우수하며 강도가 양호한 열경화성(Thermosetting) 수지가 사용된다. 열경화성 수지는 우수한 물리적 특성을 나타내지만 재사용이 어렵다. 이러한 문제를 해결하기 위하여 재사용이 가능한 탄소섬유 강화 열가소성 수지(Thermoplastic) 복합재료 개발 및 탄소섬유 재사용에 관한 많은 연구들이 진행되고 있다. 본 연구에서는 열분해 방법을 사용하여 탄소섬유/에폭시 복합재료로부터 탄소섬유와 수지를 분리하여 탄소섬유를 재활용하였다. 에폭시의 분해도(Degree of decomposition)는 열중량분석기(TGA)와 시차 주사현미경(SEM)을 통해 확인하였다. 수지로부터 분리해낸 탄소섬유는 절단(Cutting)과 그라인딩(Grinding) 방법을 거쳐 탄소섬유 복합재료 시트(Sheet)를 제조하였다. 재활용 탄소 섬유로 제조된 탄소섬유 시트는 각각 다른 냉각조건에서 결정화 엔탈피(Crystallization enthalpy)와 기계적 특성, 표면과 단면의 형태를 분석하였다.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
• /
• 제18권4호
• /
• pp.53-65
• /
• 2012

Purpose: With the increasing national interest in health, the number of health examination centers is growing rapidly, and it is growing as independent medical institutes separated from hospitals. With the growing functions and size of health examination institutes, considerations for testees, who are the most important users of the health examination centers, have taken the back seat. In particular, for health examination programs that take on a sequential traffic line, it is important to be aware of the space of each examination room, but the lack of a scientific evaluation method for this has resulted in great discomforts for testees using the health examination center. Method: Thus, this study proposes risk evaluation indices (RCF TCF, RC3, RR, ARR), and set a standard health examination program based on the national health examination program. This was applied to 11 different sized health examination centers to find their features, and together with identifying the trends of the indices, the following results were deduced. Result: 1) ARR showed a wide-range feature as the number of unit spaces increased, while RR were discovered regardless of the size, thus displaying local features. 2) The increase of ARR is affected more by internal factors in the health examination center than from outside factors. 3) By gender, when separating the basic health examination fields, the connective relation of the comprehensive health examination fields had a big effect on ARR. 4) By becoming larger, the fields of function become independent and the waiting space that results from it increases the number of total movement, so there is space for improvement in this.

• 상하수도학회지
• /
• 제25권1호
• /
• pp.85-93
• /
• 2011

The structural components of microorganism are quite related to the toxin and environmental conditions. The vegetative and dormant cells are quite affected by the physical and chemical environments to survive and they will be dormant when they are in the extreme environment. The mechanism to activate the microorganisms however, is not well defined yet in the area of activation state and sporulation state through the analysis of EPS. Other than that even the main mechanism of prior to acquisition of analysis values is not well understood. Therefore, what kind of specific environment to affect the activation and sporulation will be discussed through the analysis of the extracellular polymeric substances(EPS). EPS are a high molecular weight mixture of polymers presenting both outside of cells and interior of microbial aggregates. They are a major complex materials in microbial aggregation for sustaining them together in a three dimensional matrix. Three commonly used extraction methods were applied to this study their effectiveness and quantification in extracting EPS from several Bacillus microorganisms and activated sludge. Three extraction methods used for this study are regular centrifugation with formaldehyde (RCF), Steaming, and EDTA extraction. The results of EPS contents such as the quantitative proteins, carbohydrates and the ratio of protein versus carbohydrate from the several species with the several specific methods showed in this research. This study aims to get comparable results of the quantitative production of EPS and the effectiveness of sedimentation for Bacillus microorganisms and activated sludge from several wastewater treatment plans. The results revealed that the protein amount extracted was the highest by the Steaming method of three extraction methods before sporulation and the carbohydrate amount extracted was the highest by the RCA method of three extraction methods after sporulation. The higher amount of protein compared with carbohydrate from Bacillus microorganisms affected higher sedimentation efficiency, however it could not be found the relation between the EPS production and sedimentation efficiency for the activated sludge.