• 소성∙가공
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• 제6권4호
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• pp.329-337
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• 1997

Forging of an inner pulley for compressor clutch assembly of car air conditioner is investigated in this study. In cold forging of inner pulley, the design requirements are to keep the same height of the inner rib and the outer one, and to make uniform the hardness distribution in the forged product. Using the rigid-plastic finite element simulation. we design the optimal process conditions, which has a performing operation. Also the final product configuration of forging has to be designed again in view of the metal flow involved in the operation, derived from the finite element simulations. The forged pulley is investigated by checking the hardness distribution and it is noted that the distribution has improved to be even and high enough for industrial application.

• Journal of Welding and Joining
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• 제25권3호
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• pp.45-50
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• 2007

The present study is devoted to investigate the transient flow and to estimate the filling time fur underfill process by using the numerical model established on the fluid momentum equation. For optimization of the design and selection of process parameters, this study extensively presents an estimation of the filling time in the view points of some important factors related to underfill materials and flip-chip geometry. From the results, we conclude that the filling time changes with respect to the under fill materials because of different viscosity, surface tension coefficient and contact angle. It reveals that, as the gap height increases, the filling time decreases substantially, and goes to the saturated values.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2005년도 학술발표논문집
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• pp.399-403
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• 2005

Slope angle, ground water table and thickness of soils are the key factors affecting landslide stability. However examining the factors such as thickness of soils; geological structure, slope angle, and height, in order to use the global landslide susceptibility forecasting analysis is very expensive and time consuming effort. So most researchers prefer to use the simplest methods such as the C strata and the USGS methods. In this research thickness of soils was calculated using these two methods and stability analysis was performed with the thickness of soils calculated by the two methods at the SINMAP based on ArcView 3.2. The two safety factor maps were compared with the past landslide records. The thickness of soils calculated by USGS method showed more unstable safety factors.

• Applied Microscopy
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• 제46권2호
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• pp.71-75
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• 2016

The scanning electron microscope (SEM) offers two-dimensional (2D) micrographs of three-dimensional (3D) objects due to its inherent operating mechanisms. To overcome this limitation, other devices have been used for quantitative morphological analysis. Many efforts have been made on the applications of software-based approaches to 3D reconstruction and measurements by SEM. Based on the acquisition of two stereo images, a multi-view technique consists of two parts: (i) geometric calibration and (ii) image matching. Quantitative morphological parameters such as height and depth could be nondestructively measured by SEM combined with special software programs. It is also possible to obtain conventional surface parameters such as roughness and volume of biomedical specimens through 3D SEM surface reconstruction. There is growing evidence that conventional 2D SEM without special electron detectors can be transformed to 3D SEM for quantitative measurements in biomedical research.

• Wind and Structures
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• 제9권5호
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• pp.357-367
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• 2006

Unsteady 3D Reynolds Averaged Navier-Stokes (URANS) solver is used to simulate the turbulent flow past an isolated prismatic cylinder at Re=37,400. The aspect ratio of height to base width of the body is 5. The turbulence closure is achieved through a non-linear $k-{\varepsilon}$ model. The applicability of this model to predict unsteady forces associated with this flow is examined. The study shows that the present URANS solver with standard wall functions predicts all the major unsteady phenomena showing closer agreement with experiment. This investigation concludes that URANS simulations with the non-linear $k-{\varepsilon}$ model as a turbulence closure provides a promising alternative to LES with view to study flows having complex features.

• 한국주거학회논문집
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• 제15권2호
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• pp.55-62
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• 2004

Apartment design in residential Area is restricted by building distance limit code. Building distance limit decreases gradually to the 0.8H(height), and residential area has 250% site area ratio by building code, so site using has become efficient. In this study, examine the relationship between present building distance limit and right of daylighting environment by computer simulation. As well, high-rise residential officetel and multipurpose residential building becomes increase in commercial non-residential area. In the domestic, residential type multipurpose building made at the business area or central business area has 400∼800% site area ratio by building code. However, at a dweller's point of view, there are much lacks of environmental consideration to provide suitable daylighting environment. And, POE: Post Occupancy Evaluation is not completed yet. In this study, however, progress architectural environment prediction, basis by right of daylighting, and examine the possibility of daylighting by architectural distance limit code in residental area and by high-rise, high-density residential building in non-residental downtown area.

• 소성∙가공
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• 제7권6호
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• pp.575-585
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• 1998

An automated surface-strain measuring system using the image processing technique is developed in the present study which consists of the hardware to capture and to display digital images. and the software to calculate the 3-D informations of grid points from two views. New or improved algorithms for the mapping and establishing correspondence of grid points and elements the camera calibration and the subpixel measurement of grid points are implemented. As an application of the present system the surface-strains of deformed blanks in the limitting dome height test the square cup deep-drawing and punch stretching to obtain the forming limit diagram are measured. The results are com-pared with those obtained by conventional manual methods.

• Bulletin of the Korean Chemical Society
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• 제18권11호
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• pp.1175-1179
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• 1997

The adsorption of oxygen on ZnO was monitored by measuring the capacitance of two contacting crystals which have depletion layers originated from the interaction between oxygen and ZnO at 298 K-473 K. An admission of oxygen to the sample induced an irreversible increase in the depth and the amount of adsorbed oxygen was less than 0.001 monolayer in the experimental condition. The relation between pressure of oxygen and variation of the depth was tested from the view point of Langmuir or Freundlich isotherm. Using Hall effect measurement and kinetic experiment, a model equation on the adsorption process was proposed. From the results, it was suggested that oxygen adsorption depended on the rate of electron transfer from ZnO to oxygen while the amount of adsorbed oxygen was kinetically restricted by the height of surface potential barrier.

• Wind and Structures
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• 제2권1호
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• pp.51-68
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• 1999

Applying and extending some preceding researches, this paper proposes a map of Italian extreme winds assigning the reference velocity, i.e., the wind velocity averaged over 10 minutes, at 10 m height, in a flat open terrain, with 50 years mean return period, depending on the site and the altitude. Furthermore, an objective criterion is formulated by which the actual values of the local wind velocity are given as a function of the reference velocity. The study has been carried out in view of the revision of the Italian Standards dealing with safety and loads and the introduction of the aeolic Italian map into Eurocode 1.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.364-371
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• 2008

In general Maglev (magnetically levitated vehicle) has about 4 or 5 bogies per one vehicle to improve stability of electromagnetic suspension and 4 air-spring per one bogie are to be equipped to prevent form excessive yawing and pitching motion of bogie. 3 leveling valve per one vehcile will be applied to control the height of carbody. This kind of vehicle is on the design stage, and design review will be carried out before manufacture. The suspension system of Maglev consists of 16 of air-spring, auxiliray reservoir and orifice, 3 leveling valve, which are different composition comparative to conventional rolling stock. To improve operational reliability of vehicle, additional ventilation valve will be equipped with airspring. This kind of new design concept requires fundamental design review. In this study, suspension systems of Maglev will be built as mathematical model. Then designed suspension system will be reviewed in view of various points through proposed suspension simulation.