• 한국전산유체공학회:학술대회논문집
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• 1995.10a
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• pp.219-224
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• 1995

The adaptive wall test section has distinct advantage over the other devices for reduction of wall interference in the wind tunnel testing. For two-dimensional steady flows the wall adaption strategy has been well established and, in some extent, has been effectively applied to three-dimensional steady flows. For unsteady testing, the wall adaptation is conceptually possible but has never been realized in the wind tunnel experiment. In this study, relatively simple adaptive wall models have been proposed and evaluated through numerical tests. The effect of Mach number, frequency, and amplitude of pitching oscillation on the wall interference reduction has been also studied.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.9
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• pp.2396-2403
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• 1994

An experimental study on material characterization and mechanical properties of SMC(Sheet Molding Compounds) compression method parts was carried out. Simple compression test using grease oil as a lubricant was carried out to characterize flow stress of SMC at elevated temperatures. Two different mold temperatures, $130^{\circ}C{\;}and{\;}150^{\circ}C$ and two different mold speeds, 15, 45 mm/min were used for preparing the specimen of SMC compression molded parts. Surface roughness, tensile, and 3-point bending tests were used to determine the effects of molding temperatures and speeds on mechanical properties of compression molded SMC parts. Orientation and distribution of glass fiber in the compression molded SMC parts were also investigated by photographing the burnt flat specimen and taking SEM(Scanning Electron Microscope) of cross-sectional T-specimen.

• 한국가시화정보학회:학술대회논문집
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• 2004.11a
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• pp.68-71
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• 2004

The experiments for NACA airfoils are conducted as the preliminary study for the aerodynamic characteristics of the transonic airfoil flow in the shock tube. The test section configurations were designed to use shock tube as simple and less costly experimental facility generating transonic flow at relatively high Reynolds numbers. Experiments at hot gas Mach numbers of 0.80, 0.82 and 0.84, Reynolds numbers of about $1.2\times10^6$ on airfoil chord length and angle of attack of $0^{\circ}\;and\;2^{\circ}$ were carried out by means of shadowgraph visualization method and static pressure measurements. Visualization results were compared with the corresponding results from the conventional transonic wind tunnel tests. The results of study showed that present shock tube facility is useful to study the proper performance characteristics in transonic Mach number range.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.513-517
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• 1997

Glass fiber reinforced thermoplastic composite materials have considerable promise for increased use in low cost high volum applications because of the potential for processing by solid phase forming. However, the forming characteristics of these materials have not been well known. The primary focus of this research is the investigation of the bendability of these composites and spring-back phenomena in pure bending. The materials tested contained 10, 35, and 40 percent by weight of randomly oriented glass fiber in a polypropylene matrix. The bending tests were performed at temperatures ranging form 75 ".deg. c" to 150 ".deg. c" and at punch speeds of 2.54 mm/sec and 0.0254 mm/sec. The measured bendability and spring back angle in pure bending werw compared with the predictions based on the simple analyical models. Goog agreement between experimental and analytical results was observed.esults was observed.

• Structural Engineering and Mechanics
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• v.29 no.6
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• pp.623-642
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• 2008

While spatial plastic mechanism analysis has been widely and successfully applied to thinwalled steel structures to analyse the post-failure behaviour of sections and connections, there remains some contention in the literature as to the basic capacity of an inclined yield line. The simple inclined hinge commonly forms as part of the more complex spatial mechanism, which may involve a number of hinges perpendicular or inclined to the direction of thrust. In this paper some of the existing theories are compared with single inclined yield lines that form in flange outstands, by comparing the theories with plate tests of plates simply supported on three sides with the remaining (longitudinal) edge free. The existing mechanism theories do not account for different in-plane displacement gradients of the loaded edge, nor the slenderness of the plates, and produce conservative results. A modified theory is presented whereby uniform and non-uniform in-plane displacements of the loaded edge of the flange, and the slenderness of the flange, are accounted for. The modified theory is shown to compare well with the plate test data, and its application to flanges that are components of sections in compression and/or bending is presented.

• Computers and Concrete
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• v.4 no.2
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• pp.101-117
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• 2007

A new model predicting the nonlinear basic creep behaviour of concrete structures subjected to high multi-axial stresses is proposed. It combines a model based on the thermodynamic framework of the elasto-plastic continuum damage theory for time-independent material behaviour and a rheological model describing phenomenologically the long-term delayed deformation. Strength increase due to ageing is regarded. The general 3D solution for the creep theory is derived from a rate-type form of the uniaxial formulation by the assumption of associated creep flow and a theorem of energy equivalence. The model is able to reproduce linear primary creep as well as secondary and tertiary creep stages under high compressive stresses. For concrete in tension a simple viscoelastic formulation is applied. The material law is then incorporated into a finite element solution procedure for analysis of reinforced concrete structures. Numerical examples of uniaxial creep tests and concrete members show excellent agreement with experimental results.

• Journal of Ship and Ocean Technology
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• v.8 no.2
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• pp.29-40
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• 2004

Interaction of grounded ice ridges with underlying seabed is one of the major considerations in the design of Arctic pipeline system. Previously several ice scour models were developed by researchers to describe the ice scour-seabed interaction mechanism. In this paper, a parametric study on ice scouring mechanism is performed and the limitation of ice scour-seabed interaction models is discussed. Simple laboratory tests are carried out and then the shape pattern of deposited soil around the ice is redefined. New ice scour model assumes trapezoidal cross section based on the field observation data. Ice scour depth and soil resistance forces on seabed are calculated with varying the keel angle of a model ice ridge.

• Journal of Ship and Ocean Technology
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• v.1 no.2
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• pp.1-10
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• 1997

The prediction of the total resistance of a ship is generally based on considering it to be a simple sum of the viscous resistance and the wave resistance. An experimental approach for predicting full-size ship resistance on this basis is practical but obviously has the deficiency that a model has to be built for each prototype of interest and the resulting tank tests are time consuming. On the other hand, purely theoretical calculations of the wave resistance, using, for example, the Michell theory, require relatively little computer time and give an excellent portrayal of the overall variation of the vessel resistance as a function of forward speed. Unfortunately, there are sufficient differences between this theory and the measured results to make this method impractical for design purposes. The proposal examined here is to use a data bank of experimental resistance results to modify the theoretical predictions. It is demonstrated that the technique will produce remarkably accurate resistance predictions and can take into account the effects of the water depth, any restriction of canal or river width, as well as the prismatic coefficient, and other geometric parameters.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.727-732
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• 2000

This paper is on the development of a auxiliary power supply for the coach of Indian Railways. The auxiliary power supply system supplies the power for air-conditioners, air-compressors, lighting equipments, controllers, etc. It converts the input voltage, DC 110V which is supplied from battery, to AC 3${\Phi}$ 415V of 30kVA capacity. This is a low voltage-high current type converter system and largely consists of boost chopper and 3 phase inverter. Adopting a optimal control algorithm and simple power circuit, we realized the more reliable and competitive system for satisfaction of Indian Railway's strict requirement for vibration, temperature and dust. We completed the design, the manufacture and the field test of the system successfully and proved the system performance and reliability as a result of those tests.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.2069-2075
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• 2010

The broadcasting system for the customer safety and conveniency is one of the important convenience facilities taking charge of customer guidance, emergency situation broadcasts for the people waiting at the platform, waiting lounge and train approaching broadcasts. To maintain this broadcasting facility local management control system(LMC) is needed. LMC observes operation status of the facility components which is set up at station and the observation results are confirmed through out remote management PC installed in the jurisdiction branch office. The staff only observes and confirms the errors of the electrical power source at broadcasting facility components accordingly the real mechanical troubles are detected by on-the-spot survey. this paper deals with existing broadcasting system only acting as a simple observation function and the research of LMC function extension which controls, monitors and tests broadcasting facility.