• Transactions of the Society of Information Storage Systems
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• v.1 no.1
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• pp.53-57
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• 2005

In order to measure signal quality of optical disc such as CD or DVD, jitter is used traditionally. The signal attained from a disc by optical pick-up is processed by analog circuits. And then, binary signal can be obtained by using proper silcer. After the signal is changed into binary format, jitter is calculated as a time difference between the binary signal and the reference time. Jitter is used to express the signal quality. In this paper, a new method that is able to offer more precise measurement of the signal quality fur high density optical disc than the jitter is proposed. We named it LPSNR (Level Peak Signal to Noise Ratio). The relationship between bER (bit error rate) and LPSNR is shown in the paper.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.6
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• pp.37-46
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• 2003

This paper is to predict quality deterioration resulting from a caulking process of yoke which is a part of automotive steering system. The caluking is a plastic deformation process involving such as impact of high speed tool, contacts between part and fixtures and strain rate sensitivity of the part material. Elaborate application of finite element method is neccesary to calculate changes of part dimensions because they fall into a level of tolerances. Simple work hardening and strain rate sensitive model is proposed fur the material and applied for the simulation by using Abaqus which is able to cater for elastoplastic rate sensitive material and contacts. Numerical results of test models that represent tensile bar and tensile plate are compared with material data inputs. Dimensional changes for the yoke are calculated from simulations and compared to the mesurements and they show good agreement. The method presented here with the material model proved to be valuable to assess quality deterioration for similar metal forming processes.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2003.05a
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• pp.349-359
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• 2003

Finding the factors to affect the success of the business web sites is critical to enhance their competitiveness. This paper categorizes these factors into 4 quality measures: system information, service and entertainment. The success is measured via user's satisfaction and loyalty. It surveys 474 Internet users to find the effect of the quality measures on web site success empirically. We confirm the causal effect of quality factors on users' satisfaction and loyalty. Furthermore, a comparative study is performed fur Web site types, such as finance, e-commerce (shopping mall), and entertainment. We note that the effect differs in web site types.

• Proceedings of the Korean Fiber Society Conference
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• 1998.10a
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• pp.398-401
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• 1998

The evenness of roving is greatly important fur the improvement of quality in final yarns. In order to produce even rovings, all fibers would have to be uniformly distributed over the whole rovings. However, that is ruled out by the inhomogeneity of fiber materials aid by the mechanical constraint. Accordingly, there are limits to the achievable fiber assembly evenness. Also, since the evenness of roving has greatly influenced on the evenness of slivers in drawing process, the optimum condition of drawing process is very important. (omitted)

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2001.05a
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• pp.311-317
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• 2001

The study on Shilla monumental inscription has beer accomplished by many historians. However, the research on enhancement of monumental inscription image using digital image processing technique is not sufficient. The preprocessing using computer is needed fur accurate interpretation of history. In this paper, digital image enhancement algorithm based on mathematical morphology for noise reduction and character clearness is proposed. In the experiment, the subjective image quality is improved using the proposed algorithm.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.553-556
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• 2000

This paper suggests the way to perform the handover by predicting the movement route of the mobile terminal by considering the movement pattern of the user. By considering the fact that the most users has the constant movement pattern, the channels needed fur the handover can be reserved, and the required quality of service (QoS) is maintained during handover. The suggested algorithm makes the channel allocation schemes more efficient.

• Journal of the Korean housing association
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• v.13 no.1
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• pp.44-52
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• 2002

As a result of the expansion of the nuclear family in society, there has been an increase in the number of elderly people who want to live independently of their children. Australia is one of the countries which has initiated an extensive welfare program for its senior citizens. These services include maintenance of, and alterations to their own homes to make living conditions safer and more manageable. This case study was aimed at finding ways of adapting the services provided in Australia, to meet the needs of elderly Koreans who are in similar situations. It evaluated houses which had been renovated and altered fur the normal as well as the disabled elderly in both Melbourne and Sydney. results of research were as following : 1) Most elderly usually wished to remain as long as possible in their own home and it made them very stable in psychologically. 2) Housing maintenance and alterations were provided as one of social care services fur elderly with low expense and loan from government. 3) Many elderly were also getting various kinds of social services, fur example, meals on wheels, transportation and cleaning service with housing alterations and these ones let their quality of life more improved. 4) Occupational therapist and Architect were always involved in the process of housing alterations for disabled elderly. 5) The alterations which related to bathroom, toilet and steps were very popular and those were considered essential design guide applications for planning of housing for elderly in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.6
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• pp.497-501
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• 2005

Dry film method was applied to fabricate lead-free transparent dielectric fur PDP(Plasma Display Panel). From various slurry compositions, it was able to find out the. best composition for producing high density green sheet. The slurry exhibited shear thinning characteristics which are known to be suitable fur producing a high quality green sheet. The thermal expansion coefficient of the fabricated transparent dielectric was measured to be $97{\times}10^{-7}/^{\circ}C$ which is close to the value of the glass substrate(PD-200). Cross sectional SEM of the transparent dielectric layer on PD-200 showed that the two layers were well attached each other with no observable gaps between them.

• Journal of Microbiology and Biotechnology
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• v.10 no.2
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• pp.119-136
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• 2000

Being autotrophic, algae occupy a trategic place in the biosphere. They produce oxygen both directly and indirectly through the chloroplasts of all green plants. The chloroplasts are believed to have originated from archaic prokaryotic algae through endosymbiosis with primitive eukaryotic cells. Phytoplankton and other algae regulate the global environment not only by releasing oxygen but also by fixing carbon dioxide. They affect water quality, help in the treatment of sewage, and produce biomass. They can be used to produce hydrogen which is a clean fuel, and biodiesel, and fix $N_2$ for use as a biofertilizer. Some other services of algae to the environment include restoration of metal damaged ecosystems, reducing the atmospheric $CO_2$ load and citigating global warming, reclamation of saline-alkaline unfertile lands, and production of dimethyl sulphide (DMS) and oxides of nitrogen (NOx) involved in the regulation of UV radiation. ozone concentration, and global warming. Algae can be valuable in understanding and resolving certain environmental issues.

• Journal of Welding and Joining
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• v.20 no.2
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• pp.102-108
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• 2002

Resistance spot welding of aluminum alloys is based upon Joule heating of the components by passing a large current in a short duration. Since aluminum alloys have the potential to replace steels fur automobile body assemblies, it is important to study the process robustness of aluminum spot welding process. In order to evaluate the effects of process parameters on the weld quality, major process variables and abnormal process conditions were selected and analyzed. A newly developed two-stage, sliding-level experiment was adopted fur effective parameter design and analysis. Suitable ranges of welding current and button diameters were obtained through the experiment. The effects of the factors and their levels on the variation of acceptable welding current were considered in terms of main effects. From the results, it is concluded that any abnormal process condition decreases the suitable current range in the weld lobe curve. Pareto analysis of variance was also introduced to estimate the significant factors on the signal-to-noise (S/N) ratio. Among the six factors studied, fit-up condition is found to be the most significant factor influencing the SM ratio. Using a Pareto diagram, the optimal condition is determined and the SM ratio is significantly improved using the optimal condition.