• Proceedings of the Korea Contents Association Conference
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• 2003.05a
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• pp.411-415
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• 2003

This paper compared fuzzy thesaurus through query extension with existent thesaurus and direct matching retrieval etc. Performance of fuzzy thesaurus is evaluated by the recall and precision through simulation. An experiment did through assessment that use critical value, query extension, and reusability satisfaction. As a result of the experiment, we knew component retrieval efficiency of fuzzy thesaurus excels.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.23 no.57
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• pp.1-10
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• 2000

The purpose of this paper is to propose a method of rest to reduce work load of night shift workers for night shift work. The experiment was carried out 10minutes preparing time, 45minutes first work, 10minutes first rest, 45minutes second work, 10minutes second rest between 2 and 4 o'clock that the lowest physiological function of workers. The methods of rest set up as four patterns (1) non-action rest (2) non-action rest + listening music (3) action rest + non-action rest, (4) action rest + non-action rest + listening music. For the measurements of experiment, heart rates(R-R interval), critical flicker fusion frequency(CFF), blood pressure, oral temperature, reaction time and error rates were considered as criteria for work performance. As a result, action rest + non-action rest and action rest + non-action rest + listening music were more effective to reduce work load additional work than non-action rest and non-action rest + listening music.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.366-370
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• 1997

This paper descibes a micro groove machining process on the polyurethane biopolymer by KrF excimer laser. To investigate the etch charcteristics of polyurethane biopolymer quantitatively,laser system for ablation was installed with high precison moter and then polymer ablation experiment, in which paramteters were fluence,pulse repetition rate,numbers of pulses and assist gas, was carred out. In this experiment, we found out that the value of critical energy density for ablation is 30mJ/cmsup2/ and the etching rate is more dependent on the pulse number and fluence than any other pamameter. Finally, we machined micro grooves for fiexibility as width 300.mu.m depth 100.mu.m and port for micro-devices mounting as length 100.mu.m width 300.mu.m depth .mu.m on the outer wallof polyurethane biopolymer tube which is used as medical device.

• Journal of the Ergonomics Society of Korea
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• v.26 no.4
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• pp.17-24
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• 2007

Analyses of eye tracking and think-aloud protocol data were performed to examine novice-expert differences in perceptual and cognitive aspects of air traffic controllers' situation awareness. In Experiment 1, three groups of field air traffic controllers (experts, intermediates, novices) were asked to perceive situations that were manipulated by situation complexity. In Experiment 2, protocol analysis for previous situation awareness tasks was performed to extract different task models and strategy models as a function of expertise. Then delayed-recall task and interviews about air control plans for the recalled situations were also executed. Results showed that expert controllers concentrate only on several critical features and have their own strategies to reduce mental workloads.

• Journal of the Optical Society of Korea
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• v.18 no.4
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• pp.370-376
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• 2014

We optimized the design of the flat encapsulant of a light-emitting diode (LED) package to obtain higher light output power (LOP), both by experiment and simulation using three-dimensional ray-tracing software. In the experiment, the refractive index of the encapsulant was varied (1.41 and 1.53). In addition, double-layer structures with these refractive indices (1.41/1.53) were investigated by varying the shape of the interface between the two among flat, concave, and convex. The experiments showed that the LOP of the double-layer encapsulant with convex interface increased by 13.4% compared to the single-layer encapsulant with a refractive index 1.41, which was explained by the increase of the light extraction efficiency (LEE) in connection with the increase of the critical angle (${\theta}_c$) and the decrease of the Fresnel reflection.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.341-348
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• 1999

In the finite elemenet analysis of metal forming problems, the most critical input is the flow stress of workpiece. Conventionally, the flow stress of a metal at elevated temperatures is assumed to be a function of strain, strain rate and temperature, and obtained by experiment. However, if the workpiece is not continuously deformed as in mulit-pass rolling, the flow stress obtained by experiment is no longer valid because it does not consider the microstructure evolution occurring between deformations. In the present study, it was attemped that the flow stress of steel in the austenite region be obtained equations. It was applied to the prediction of flow stress variation at each stand during hot finishing rolling of steel.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.1
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• pp.1-8
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• 2004

Thermal distortion is a critical issue in machine tools, especially in high speed machining. This is the reason why recent machine tools have thermal compensation function. To compensate thermal distortion, it is necessary to make a model that has some relationship between temperature and deformation. Various experimental methods ye widely been used in thermal test: constant spindle speed, unit step speed increase, random spindle speed, etc. This paper focuses on which type of spindle operation condition is good for thermal experiment. Also, experimental data is modeled using multiple linear regression models and compared each other to select a method. Consequently, it turned out at e condition of 75％ constant of maximum spindle speed is good enough to generate temperature and distortion data.

• Fisheries and Aquatic Sciences
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• v.3 no.2
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• pp.163-171
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• 2000

A series of numerical experiments are performed to examine the generation of inter-annual variations by an inertial current in an idealized semi-enclosed basin with dimension comparable to that of the East Sea. Model results indicate that the inter-annual variations dominate the kinetic energy spectrum with a peak around the time scales of 2-3 years. These variations are mostly due to the westward propagating meanders and large eddies induced by the instability of current, indicating their dependency on the eddy-resolving capacity of the model. They are generated in the interior of the basin but their energy is largely confined near the western boundary such that the east-west dimension of the basin cannot be considered as a critical factor as long as the basin covers enough western boundary region. Overall, this study suggests that the inter-annual variation observed in the East Sea is due to the meandering and large eddies induced by the instability of the current.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.3
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• pp.98-104
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• 2009

The objective of this paper is to investigate the effect of factors on the dynamic stiffness variation of boring bar. The experiment was carried out by Taguchi Method and Orthogonal array table. The results indicate that overhang was found out to be dominant factor with 95% confident intervals and feed rate and depth of cut were insignificant. In addition, analysis of loss function shows that loss value increased sharply from 3D to 4D(D is a shank diameter). Consequently, there is critical point which changes property of dynamic stiffness.

• Corrosion Science and Technology
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• v.3 no.5
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• pp.179-186
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• 2004

Recently the alloy development of duplex stainless steel has been done. On this study we studied the effect of the corrosion resistance according to the composition variety of C, Cr, N in the alloy elements of duplex stainless steel. materials which have below 0.1[mm/year] corrosion rate enable to use for corrosion-resisting materials, generally. On this experiment we inspected the effect of the composition variety of C, Cr, N in duplex stainless steel and the heat treatment, which the condition was the water quenching after the heat treatment for 1hr. The experiment was done on the basis of the ASTM G48A test, Critical pitting temperature(CPT), and ASTM G-61(Electrochemical tests for cyclic polarization).