• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.167-172
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• 2000

There are a variety of factors affecting measured compressive strength of hardened concrete. One of them is the end surface condition of concrete specimen. So, many capping methods have been developed for the specimen to meet the end condition requirement of ASTM C 39. A series of experimental strength comparison study was carried out using several representative capping methods, including pad capping method which is one of unbonded elastomeric capping system and was newly adopted in the ASTM standard. A comparison was also focused on their economy, convenience, harmfulness, etc.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.2
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• pp.123-134
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• 1995

In this paper, the fast force algorithm has been studied so that it is used to calculate cutting forces and to develope the NC verification system. The NC verification using the fast force algorithm can verify excessive cutting force which is the cause of deflection and breakage of tool, and adjust the feed rate and spindle speed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.4
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• pp.7-12
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• 2012

The cutting force for peripheral end-milling considering run-out property was estimated and its result was compared with that of measured one. An experimental coefficient modelling was used for the formulation of theoretical end-milling force by considering the specific cutting force coefficient. Also, the specific cutting force, that is the multiplication of specific cutting force coefficient and uncut chip thickness, was used for the prediction of end-milling force. The end-milling force mechanics with run-out was presented for the estimation of theoretical force in peripheral end-milling by considering the geometric shape of the workpiece part. As a result, the estimated end-milling force shows a good consistency with the measured one. And it can be used for the prediction of force history in end-milling with run-out which incurs different start and exit immersion angle in entering and exiting condition.

• Proceedings of the SAREK Conference
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• 2006.11a
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• pp.9-9
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• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1025-1028
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• 2001

In this report, a new method compounding the electrolytic machining with ball end milling process to increase the machining efficiency was introduced. From the experimental result, it was confirmed that effect of cutting force reduction and finer surface roughness can be obtained in a certain condition of ball end milling and electrolytic machining conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.959-962
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• 2000

A new method compounding the electrolytic machining with ball end milling process to improve machined surface toughness was examined. From this study, it was confirmed that much smaller cutting force and finer surface roughness can be obtained in a certain condition of ball end milling and electrolytic machining conditions.

• Journal of Mechanical Science and Technology
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• v.14 no.9
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• pp.928-934
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• 2000

This paper describes a method developed for the simulation of ring pack lubrication characteristic in an internal combustion engine. In general, the quantity of oil supply for piston ring lubrication may be insufficient in filling the entire volume formed at the interference between the piston ring and the cylinder liner. Thus the oil starvation condition should be considered in analyzing piston ring lubrication. In order to reasonably estimate the amount of oil left over on the cylinder liner, the flow rate at the posterior portion of the interface should be calculated with an adequate boundary condition that confirms flow continuity condition. In this analysis, oil starvation and open-end boundary conditions are considered at the inlet and outlet of the piston rings. The lubrication characteristic of each piston ring is obtained by an iterative method with sequential steps. It is revealed that piston rings are operated under oil starvation in most operating cycles and the result under these conditions are quite different from that with the fully-flooded assumption.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.1
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• pp.31-36
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• 2009

Micro-machining technology has been adopted for shape accuracy of micrometer and sub-micrometer scale, surface roughness of tens nanometer in industries. In micro-machining process the quality of machined surface is derived from machining condition and tooling. This paper investigates AE(acoustic emission) and cutting force signals according to machined surface quality related to machining condition. Machined surface quality was analyzed by the AE and cutting force parameter which reflect surface morphology. The characteristics of signal were extracted for process optimization by monitoring both the tool condition and the machined surface texture in micro end milling process.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.5 s.113
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• pp.63-69
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• 2005

This study was performed to introduce recently developed polyvinylamine as a wet-end process and paper strength improving aids. As a retention and drainage aids, high cationic charged polyvinylamine was more effective at the BCTMP and ONP stock condition than LBKP stock condition. As a dry tensile strength aid, dual system of polyvinylamine with anionic polyacrylamide was the best at the LBKP or ONP stock conditions. On the other hand, polyvinyl amine alone was better than dual system of polyvinylamine with anionic polyacrylamide at the BCTMP condition. As a wet tensile strength aid, polyvinylamine single system and dual system of polyvinylamine with anionic polyacrylamide were good at LBKP, BCTMP and ONP stock conditions. However, poly(aminoamide)-epichlorohydrin resin was good at LBKP and ONP stock conditions but efficiency of poly(aminoamide)-epichlorohydrin resin was remarkably decreased at BCTMP stock condition.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.18 no.3
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• pp.34-41
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• 2010

'Aviation Safety' is the state in which the risk of harm to persons or of property damage is reduced to, and maintained at or below, an acceptable level through a continuing process of hazard identification and risk management in the aviation field. 'Risk' is the assessed potential for adverse consequences resulting from a hazard and 'Risk assessment' involves consideration of both the frequency and the severity of any adverse consequence. This study focused on the risk frequency about a case airport which does not meet the 'Runway end safety area' requirement of ICAO SARPs and Korea standards and used 'RSA risk model' for estimating the risk frequency. As results of this study, risk frequency of the runway end safety areas in the case airport is higher than that of 'Runway end safety area' requirement of ICAO SARPs and Korea standards, which means that alternatives for risk frequency mitigation to a level as low as reasonably practicable is required in the case airport. The optimum solution analysed from this study is to impose restriction of aircraft operation when the runway condition is poor(icing condition) and also it snows in the case airport.