• IE interfaces
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• v.9 no.2
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• pp.119-128
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• 1996

A procedure is presented for a 3D-contour machining without cutter interferences. The 3D-contouring machining along a spatial curve is often required for manufacturing trimming and flange dies in motor industries. Input data for the machining contour is a spline curve with polynomial vector equation provided by CATIA system. Points are sampled on the contour curve and line segments and helical curves are approximated from the point data. Cutter interference is checked on the approximated spline and all of interference curves are substituted with interference-free helical curves for a tool path generation. The non-machined curve areas are locally machined by tools with smaller diameters. A tool radius offset is considered for generating NC data to be free with tool size.

• Proceedings of the KSRS Conference
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• 2007.03a
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• pp.308-310
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• 2007

복사 보정에 해당하는 NUC(Non-Uniformity Correction)은 MSC 각각의 픽셀들이 가지는 상이한 특성을 균일한 이미지를 얻기 위해 보정하는 작업으로서 KOMPSAT-2 검보정 작업 중 Video Processor 의 Electrical Gain/Offset 의 보정 과 더 불어 매 우 중요한 비중을 차지하는 과정이다. 본 논문에서는 KOMPSAT-2 의 Panchromatic 밴드의 raw image 를 이 용한 NUC 보정 작업 의 과정과 그 결과에 대해서 소개하고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.12
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• pp.3246-3255
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• 1996

A threshold voltage extraction scheme which does not need matched replica of the MOSFET under test is proposed. In contrast to alternative methods, the accuracy of the proposed scheme does not depend on the matching of the test transistors. The proposed scheme has been implemented in a matching-free way using a switched-capacitor subtracting ampliier and a dynmic current mirror. Nonideal effects associated with these circuits, such as non-zero offset voltages and finite gains of op-amps, capcitor mismateches, and charge injection of MOS switches, are investigated and compensated. The circuit has been designed using ISRC 1.5.mu.m CMOS process parameters andfabricated at Inter-University semiconductor Research Center, and its performance has been evaluated.

• Journal of the Korea Computer Graphics Society
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• v.4 no.2
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• pp.69-75
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• 1998

Ruled surfaces are useful concept for surface design because they are defined by the one-parameter family of lines. In this paper, we prove that the offsets of a developable surface (a special class of ruled surfaces) are developable surfaces. Moreover, we prove that the offsets of a non-developable ruled surface cannot be ruled surfaces.

• Journal of Mechanical Science and Technology
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• v.17 no.12
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• pp.2078-2086
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• 2003

As technology advances with development of new materials, it is important to measure the thermal diffusivity of material and to predict the heat transfer in the solid subject to thermal processes. The measurement of thermal properties can be done in a non-contact way using photothermal displacement spectroscopy. In this work, the thermal diffusivity was measured by analyzing the magnitude and phase of deformation gradient. We proposed a new data analysis method based on the real part of deformation gradient as the pump-probe offset value. As the result, compared with the literature value, the measured thermal diffusivities of materials showed about 3 % error.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.3
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• pp.134-140
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• 2008

Micro electrochemical machining (ECM) is conducted on stainless steel 304 using non-toxic electrolyte of citric acid. Electrochemical dissolution region is minimized by applying a few hundred second duration pulses between the tungsten SPM tip and the work material. ECM characteristics according to citric acid concentration, feeding velocity and electric conditions such as pulse amplitude, pulse frequency, and offset voltage are investigated through a series of experiments. Micro holes of $60{\mu}m$ in diameter with the depth of $50{\mu}m$ and $90{\mu}m$ in diameter with the depth of $100{\mu}m$ are perforated. Square and circular micro cavities are also manufactured by electrochemical milling. This research can contribute to the development of safe and environmentally friendly micro ECM process.

• Earthquakes and Structures
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• v.7 no.4
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• pp.401-414
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• 2014

The economic consequences of large earthquakes require a revolutionary change in the seismic performance objective of residential and commercial buildings. The majority of total construction costs consist of non-structural and architectural costs. Therefore, the aim of this research is to upgrade current Life Safety performance objectives and to offset adverse effects on country's economy after an occurrence of large earthquakes. However, such a proposal cannot easily prove the feasibility of cost-benefit analysis in structural design. In this paper, six generic reinforced concrete frames and dual system structures designed based on Turkish Seismic Code were used in cost analysis. The study reveals that load bearing structural systems with Immediate Occupancy performance level in seismic zones can be achieved with negligible costs.

• Geomechanics and Engineering
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• v.12 no.6
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• pp.965-981
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• 2017

Stability of vertical escarpments has been the subject of discussion for long time. However, available literature provides scarce knowledge about the effect of the formation of undercut and surface cracks on the stability of a vertical escarpment. The present study deals with a systematic analysis of the effect of surface cracks and undercut on slope stability using finite element based lower bound limit analysis. In the present analysis, the non-dimensional stability factor (${\gamma}H/c$) is used to inspect the degrading effect of undercut and cracks developed at different offset distances from the edge of the vertical escarpment. Failure patterns are also studied in detail to understand the extent and the type of failure zone which may generate during the state of collapse.

• Steel and Composite Structures
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• v.29 no.2
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• pp.161-173
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• 2018

Point bending is often used for cambering and curving structural steel girders. An analytical solution, applicable in the elasto-plastic range only, that relates applied loads to the desired curve was recently developed for inducing horizontal curves using four-point bending. This solution does not account for initial residual stresses and geometric imperfections built-in hot-rolled sections. This paper presents results from a full-scale test on a hot-rolled steel section curved using four-point bending. In parallel, a numerical analysis, accounting for both initial geometric imperfections and initial residual stresses, was carried out. The models were validated against the experimental results and a good agreement for lateral offset and for strain in the elasto-plastic and post-plastic ranges was achieved. The results show that the effect of initial residual stresses on deformation and strain is minimal. Finally, residual stresses due to cold bending calculated from the numerical analysis were assessed and a revised stress value for the service load design of the curved girder is proposed.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.557-563
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• 2010

Mode II interlaminar fracture toughness was measured and fractured surfaces were observed of carbon/epoxy and glass/epoxy woven fabric composites for carbody structure. Woven fabric carbon/epoxy and glass/epoxy composites that made with prepreg and epoxy resin(RS1222) are used in carbody structure of Korean tilting train(TTX) and low floor bus. ENF(End Notched Flexure) specimens having $120mm{\times}20m{\times}5mm$ shape and 35mm initial crack were made with each composites and three point bending tests according to ASTM D790 were conducted for these specimens. Crack lengths in tests were recorded using optical microscope and digital camcorder. NL(Non Linear), 5% offset and Max. load points in load -displacement curves were checked and mode II interlaminar fracture toughness of these points were calculated and compared. Fractured surfaces of specimens were observed using optical microscope and mode II delamination behavior of each composites was discussed.