• 대한기계학회논문집A
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• 제27권4호
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• pp.608-613
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• 2003

In this paper, the effect of interconnected boundary between journal and thrust bearings on the performance of self-acting air-lubricated bearings is investigated. When journal and thrust bearings have common boundary, conventional boundary condition which assumes that the boundary pressure is equal to atmosphere is no more valid. Instead, new boundary condition by mass conservation at interconnected boundary is needed. To do this, a duct model satisfying mass conservation at interconnected boundary is developed. Using this model, pressure distribution at interconnected boundary is numerically analyzed with changing the volume of interconnecting part. As a result, it is shown that load capacity of thrust bearing can be greatly increased when journal and thrust have a common boundary.

• Structural Engineering and Mechanics
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• 제4권2호
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• pp.191-202
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• 1996

This paper presents a construction of adaptive boundary element for the problem with mixed boundary conditions such as heat transfer between heated body surface and surrounding medium. The scheme is based on the sample point error analysis and on the extended error indicator, proposed earlier by the authors for the potential and elastostatic problems, and extended successfully to multidomain and thermoelastic analyses. Since the field variable is connected with its derivative on the boundary, their errors are also interconnected by the specified condition. The extended error indicator on each boundary element is modified to meet with the situation. Two numerical examples are shown to indicate the differences due to the prescribed boundary conditions.

• Steel and Composite Structures
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• 제39권5호
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• pp.543-564
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• 2021

In this study free vibration analysis of a cracked Goland composite wing is investigated. The wing is modelled as a cantilevered beam based on Euler- Bernoulli equations. Also, composite material is modelled based on lamina fiber-reinforced. Edge crack is modelled by additional boundary conditions and local flexibility matrix in crack location, Castigliano's theorem and energy release rate formulation. Governing differential equations are extracted by Hamilton's principle. Using the separation of variables method, general solution in the normalized form for bending and torsion deflection is achieved then expressions for the cross-sectional rotation, the bending moment, the shear force and the torsional moment for the cantilevered beam are obtained. The cracked beam is modelled by separation of beam into two interconnected intact beams. Free vibration analysis of the beam is performed by applying boundary conditions at the fixed end, the free end, continuity conditions in the crack location of the beam and dynamic stiffness matrix determinant. Also, the effects of various parameters such as length and location of crack and fiber angle on natural frequencies and mode shapes are studied. Modal analysis results illustrate that natural frequencies and mode shapes are affected by depth and location of edge crack and coupling parameter.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.487-491
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• 2004

For tile hydrogeological data of the National Groundwater Monitoring Wells(NGMW), a statistical analysis is made to reveal aquifer characteristics of the country. Results of the pumping and recovery test are classified into 4～5 types by the pattern of drawdown and residual drawdown curves. The analysis of aquifer characteristics shows that the hydraulic conductivity of alluvial aquifers is greater than that of fractured-rock aquifers. The hydraulic conductivity of alluvial aquifers slightly increases as the distance to the discharge area decreases. 77.5% of the NGMWs, where the distance to the discharge area is more than 100m, shows the constant head boundary. This result suggests that the fractured and the alluvial aquifers are fairly interconnected, and water can be supplied from one aquifer to tile other where pumping tests are performed. It is analyzed that the wells showing the impermeable boundary are influenced by small scale of aquifers, poor aquifer transmissivities, and impermeable layers.

• 한국생산제조학회지
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• 제19권2호
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• pp.251-259
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• 2010

It is presented in this study a new efficient intelligent machining strategy, which can be used to remove the uncut volume at the boundary region of curved surfaces caused by cutter interference. The geometric form definitions and recognition of topological features of the surface triangulation mesh are used to generate cutter paths along successive and interconnected steepest pathways, that minimize the cusp height left after flat end milling. In order to machine the uncut volume gradually, the z-map cutter centers are adjusted to avoid cutter interference for the 6 kinds of avoidance types. And then, the generative subsequent paths are sequenced to determine the second step cutter paths for the next uncut volume. For the 2 kinds of test models with convex and concave surface region, the implemented software algorithm is evaluated by investigating the residual swelling of uncut volume for each machining step.

• Applied Microscopy
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• 제45권1호
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• pp.32-36
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• 2015

The microstructural features of FeCoCrNi, FeCoCrNiAl and FeCoCrNiSix (x=0, 5, 10, 15, 20) alloys have been investigated in the present study. The microstructure of FeCoCrNi alloy changes dramatically with equiatomic addition of Al. The fcc irregular shaped grain structure in the as-cast FeCoCrNi alloy changes into the bcc interconnected structure with phase separation of Al-Ni rich and Cr-Fe rich phases in the as-cast FeCoCrNiAl alloy. The microstructure of FeCoCrNi alloy changes with the addition of Si. With increasing the amount of Si, the fcc structure of the grains is maintained, but new phase containing higher amount of Si forms at the grain boundary. As the amount of Si increases, the fraction the Si-rich grain boundary phase increases.

• Earthquakes and Structures
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• 제24권3호
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• pp.165-181
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• 2023

The effectiveness of fluid viscous dampers (FVDs) on dynamic response mitigation of coupled two adjacent structures was investigated, considering soil-structure interaction (SSI) effects under earthquake excitation. A numerical procedure was employed to evaluate system response. The finite elements were used for the numerical treatment of the adjacent buildings and soil region. Viscous boundary conditions were used as special non-reflecting boundaries on the edges of finite soil region. According to the results, the FVDs were found to be very effective for dynamic response mitigation of the adjacent buildings, even if considering the soil medium. The results showed that the most affecting parameter on the system response was found to be soil type. It was also concluded that when adjacent structures coupled by FVDs, the maximum values of the roof displacements, the base shear forces, and the base bending moments could decrease up to around 50%. Changing in lateral stiffness of the one building has minor effects on the effectiveness of viscous dampers.

• 연구논문집
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• 통권31호
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• pp.113-125
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• 2001

Silicon addition in titanium alloys generally results in solid solution hardening by silicon itself and precipitation hardening by titanium silicides. The morphology and distribution of the titanium silicides depend upon the alloy chemistry or the heat treatment condition, and play an important role in improving the mechanical properties of the alloys. In this study, the morphology and crystallographic characteristics of the titanium silicides in the Ti-Fe-Si alloy system were studied. Three types of silicides were found in the alloys; (1) interconnected chain-like silicides at grain boundary, (2) coarse silicides over im, (3) fine silicides smaller than 0.2m. Ti3Si was dominant in cast + HIP condition while Ti5Si3 was dominant in as-cast state. It is recognized that $Ti_5Si_3$$\rightarrow$$Ti_3Si$ transition occurred by the peritectoid reaction and it may be promoted by the pressure during HIP. However, in the case of the fine silicides, $Ti_3Si$ and $Ti_5Si_3$ were found simultaneously even after HIP. Such a fine silicide was found to have a crystallographic orientation relationship with matrix.

• 한국실내디자인학회논문집
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• 제23권5호
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• pp.51-57
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• 2014

In the early 20st century, created distrust on the mechanistic and dualistic view based on the world of Descartes and Newton. As the features of this new science cannot be explained by the existing Western philosophy but can be explained by the thinking system immanent in the Oriental traditional thought, many scientists and philosophers are concentrating their interests on the Oriental philosophy. In addition, some have been making efforts to find solutions needed for a new paradigm from the thinking system of the Orient. A variety of discussions have also been raised in connection with architecture due to this philosophical change. It has now become possible to conduct free creative acts, staying away from physical limitations, including gravity by diversified simulations through a computer. This physical liberation in turn has caused new changes to the spatial concept of architecture, thereby granting the freedom of the expression that could not be even imagined before and opening a possibility of new architecture and space. At the same time, the digital space architecture actively accommodating this technology is generating a phenomenon that the existing physical and realistic things are rapidly being changed gradually to immaterial and unrealistic ones. This study has analyzed the properties of digital architectural space as the immateriality of our traditional architectural space. The results are as follows: It can be seen that the immaterial features exhibited in the digital architectural space and the traditional architectural one are not just interconnected with specific features, but they are correlated to all immaterial features. Thus, immateriality that are common in the traditional and digital architectural spaces is complementary organic, which is contained in the ambiguity of boundary between other spaces. It is regarded to the architecture as a living things in space diversity based on ideological similarities.

• 한국경제지리학회지
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• 제7권2호
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• pp.315-328
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• 2004

본 연구는 자치단체의 행정구역을 넘어서서 확장되고 있는 산업클러스터를 지원하기 위한 산업지원체계의 구축에 관한 것이다. 많은 산업클러스터들은 두 개 혹은 그 이상의 자치단체를 넘어서서 확대되는 경향이 있는 바, 이렇듯 산업클러스터가 행정구역의 범위를 넘어서 성장함에 따라, 이를 뒷받침하는 행정지원체계에 있어서 다양한 문제가 발생할 수 있다. 무엇보다도 산업클러스터가 필요로 하는 산업지원서비스나 인프라공급이 원활히 되지 않거나 자치단체간의 이해 상충에 의해 서비스나 인프라 구축의 효율성이 저하될 수 있는 것이다. 본 연구에서는 산업클러스터를 지방정부간 협력에 의해 광역적 차원에서 구축하거나 지원하는 다양한 사례들을 검토하여 이들의 유형을 네 가지로 구분하였다. 그리고 이러한 분석으로부터 정책적 시사점을 추출한 바, 광역적 산업지원체계의 구축은 주로 '지역개발기구 설립에 의한 외자유치', '광역적 산업단지의 협력적 개발', '광역적 클러스터를 지원하는 통계 및 정책 개발, '클러스터내 기업들을 중심으로 대학, 연구기관간의 전자네트워크 구축' 등에 중점을 두는 것이 바람직한 것으로 종합되었다.