• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.781-785
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• 2005

Cutting forces and tool deflection in end milling are represented as the closed form of tool rotational angle and cutting conditions. The discrete cutting forces caused by tool entry and exit are continued using the Fourier series expansion. Tool deflection is predicted by direct integration of the distributed loads on cutting edges. Cutting conditions, tool geometry, run-outs and the stiffness of tool clamping pan are considered for cutting forces and tool deflection estimation. Compared to numerical methods, the presented method has advantages in short prediction time and the effects of feeding and run-outs on cutting forces and tool deflection can be analyzed quantitatively. This research can be effectively used in real time machining error estimation and cutting condition selection for error minimization since the ferm accuracy is easily predicted by tool deflect ion curve.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.4
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• pp.99-106
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• 2002

In the composite deck system, beams and deck plates deflect during construction. This lens-shaped deflection may cause problems in the serviceability of a building. Therefore, it should be compensated to be level. Several methods for leveling of floor slab are available, such as (1) increasing stiffness of structural members, (2) propping floor system, (3) cambering beams, (4) pouring additional concrete. In this study, additional weight and volume of concrete for level compensation are examined for various size of floors.

• Computational Structural Engineering : An International Journal
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• v.1 no.1
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• pp.11-20
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• 2001

The paper describes the conceptual design, structural modelling and wind load analysis of tall buildings. The lateral stiffness of the building can be obtained economically through the interaction of core walls with peripheral frame tube and/or bundle of frame tubes and integrated design of the basement. The main structural components should be properly distributed such that the building will deflect mainly in the direction of the applied force without inducing significant response in other directions and twist. The cost effectiveness can be further enhanced through close consultation between architects and engineers at an early stage of conceptual design. Simplified structural modelling of the building and its response in three principal directions due to wind load are included. Effects of the two main structural components on the performances of a 70-story reinforced concrete building in terms of peak drift and maximum acceleration under wind load are discussed.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.8
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• pp.164-174
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• 1996

As tools for machining precision componants, end mills and ball end mills are widely used. For the end mills have longer cylindrical shape comparing dianeter, they are liable to deflect when machining and induce geometrical error and deterioration of surface roughness. To improve the stiffness and the sharpness of the cutting edge of end mill, a software for manufacturing end mills are developed. The program predicts the result of helical flute grinding and the configuration of cuting edge which is located in cylindrical surface. Furthermore to facilitate the manufacturing end mills using CNC grinding machine, the setting condition which satisfy the geometrical requirements like tool rake angle and stiffness are obtained.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.10 no.1
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• pp.18-31
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• 2000

A stack must be designed to 1) reduce or eliminate rainfall or snowfall into a industrial exhaust system, 2) minimize a resistance to flow, 3) maximize the vertical dispersion of the contaminated air and 4) minimize maintenance. The weather cone stacks and the elbow-type stacks are very popular in Korea. But they add some resistance to the exhaust system resulting in reduction of air flow rate, but also deflect the noxious contaminants downward in undiluted form. To solve these problems, ACGIH (American Conference of Governmental Industrial Hygienists) suggested the vertical discharge stack with concentric space between the upper stack with larger diameter and the lower stack with smaller diameter. The preliminary test showed that the vertical discharge stacks did not have the good rainfall protection. The reversed cone were newly devised to satisfy the requirements for the good stack. Subsequently, the amount of rain being penetrated through the stacks was measured while the stacks were simultaneously and naturally exposed to rain in the same area outside. Test results indicate that none of the stacks tested completely exclude rain. The efficiency of rainfall protection and the pressure loss coefficient were compared. The temporary conclusion was reached to the point that the reversed cone stack is the best one. Further research is underway.

• Journal of the Earthquake Engineering Society of Korea
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• v.19 no.6
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• pp.257-263
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• 2015

Recently two seismic cloaking methods of earthquake engineering have been suggested. One is the seismic wave deflection method that makes the seismic wave bend away and the other is the shadow zone method that makes an area that seismic waves cannot pass through. It is called as seismic cloaking. The fundamental principles of the seismic cloaking by variable refractive index were explained. A two-dimensional cylindrical model which was composed of 40 layers of different density and modulus was tested by numerical simulation. The center region of the model to be protected is called 'cloaked area' and the outer region of it to deflect the incoming wave is called 'cloaking area' or 'cloak area.' As the incoming surface wave is approaching to the cloaking area, the refractive index is decreasing and, therefore, the velocity and impedance are increasing. Then, the wave bends away the cloaked area instead of passing it. Three cases are tested depending on the comparison between the seismic wavelength and the diameter of the cloaked region. The advantage and disadvantage of the method were compared with conventional earthquake engineering method. Some practical requirements for realization in fields were discussed.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.4
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• pp.53-60
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• 2003

CCD(Charge-Coupled Device) wafers, with a layer of micro lenses on top, usually are not passivated with dielectric films. Micro lenses, in general, are made of polymer material, which usually has a large affinity for particles generated in the various chip fabrication processes, most notably the wafer sawing for chip-dicing. The particles deposited on the micro lens layer either seriously attenuate or deflect the incoming light and often lead to CCD failure. In this study we introduce new type of saws which would significantly reduce the particle-related problems found in conventional type of saws. In the new saws, the positions and diverging angles of side and center nozzles have been optimized so as to flush the particles effectively. In addition, an independent nozzle is added for the sole purpose of flushing the generated particles. The test results show that, with the new saws. the ratio of the particle-related CCD chip failures has been dropped drastically from 9.1% to 0.63%.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.3
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• pp.537-543
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• 2002

This paper examines a new in-process measurement system for the measurement of micro-defects on the surfaces of brittle materials by using the AFM (Atomic Force Microscopy). A new AFM scanning stage that can also perform nano-scale bending of the sample was developed by adding a bending unit to a commercially available AFM scanner. The bending unit consists of a PZT actuator and sample holder, and can perform static and cyclic three-point bending. The true bending displacement of the bending unit is approximately 1.8mm when 80 volts are applied to the PZT actuator. The frequency response of the bending unit and the stress on the sample were also analyzed, both theoretically and experimentally. Potential surface defects of the sample were successfully detected by this measurement system. It was confirmed that the number of micro-defects on a scratched surface increases when the surface is subjected to a cyclic bending load.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.6
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• pp.907-914
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• 2012

Flexible pipes take advantage of their ability to move, or deflect, under loads without structural damage. Common types of flexible pipes are manufactured from polyethylene (PE), polyvinyl chloride (PVC), steel, glass fiber reinforced thermosetting polymer plastic (GFRP), and aluminum. In this paper, we present the result of an investigation pertaining to the short-term behavior of buried polyethylene pipe. The mechanical properties of the polyethylene pipe produced in the domestic manufacturer are determined and the results are reported in this paper. In addition, vertical ring deflection is measured by the laboratory model test and the finite element analysis (FEA) is also conducted to simulate the short-term behavior of polyethylene pipe buried underground. Based on results from soil-pipe interaction finite element analyses of polyethylene pipe is used to predict the vertical ring deflection and maximum bending strain of polyethylene pipe.

• Steel and Composite Structures
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• v.8 no.3
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• pp.217-230
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• 2008

The increasing use of performance-based approaches in structural fire engineering design of multi-storey composite buildings has prompted the development of various tools to help quantify the influence of tensile membrane action in composite slabs at elevated temperatures. One simplified method which has emerged is the Bailey-BRE membrane action method. This method predicts slab capacities in fire by analysing rectangular slab panels supported on edges which resist vertical deflection. The task of providing the necessary vertical support, in practice, requires protecting a panel's perimeter beams to achieve temperatures of no more than $620^{\circ}C$ at the required fire resistance time. Hence, the integrity of this support becomes critical as the slab and the attached beams deflect, and large deflections of the perimeter beams may lead to a catastrophic failure of the structure. This paper presents a finite element investigation into the effects of vertical support along slab panel boundaries on the slab behaviour in fire. It examines the development of the membrane mechanism for various degrees of edge-beam protection, and makes comparisons with predictions of the membrane action design method and various acceptance criteria.