• Communications for Statistical Applications and Methods
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• v.7 no.3
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• pp.871-884
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• 2000

Using simulation, we compare the perturbation analysis estimate and the forward difference estimate for the first and second derivatives of performance measures in a Markov renewal process. We find the perturbation analysis estimate has much les mean squared error than the traditional forward difference estimate.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.45
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• pp.347-356
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• 1998

For assessing the capability of a process, the quantification of process location and variation is central to understanding the quality of units produced from the manufacturing process. Conventional process capability indices is insufficient to drive out the information for process condition, furthermore it is very difficult to evaluate the process capability accurately when the target value is not consistent with the center of specification, and/or the shape of distribution is changed, but the process incapability indices is enable to provide more detailed information to evaluate the process capability by dividing information about the process mean and variance. In this paper, we have a brief review and comparison about these indices, provide an understanding of the relationships between the process capability indices and the incapability indices. And we explore the strengths and weakness of these indices as they apply to normally distributed process, and to examine the effect that non-normality has on these indices.

• Journal of Korean society of Dental Hygiene
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• v.12 no.5
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• pp.861-870
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• 2012

Objectives : This study has made a comparison of the difference between the periodontal parameter before and after applying dental hygiene process on patients requiring supportive periodontal therapy at a private dental clinic. Methods : The entire process was conducted on 74 patients. As a result of analyzing the difference in periodontal parameters such as PPD>4mm, BOP, and O'Leary Index of 29 patients that has completed 1 circle of dental hygiene process. Results : All periodontal parameters in all subject patients had been significantly reduced(p<0.05). Furthermore, as a result of comparing the periodontal conditions of the smoking group and non-smoking group, complier and non-complier, all parameters were reduced with a significant difference in the non-smoking group and the complier, but the smoking group and the non-complier did not show difference in all parameters. As a result of making an assessment of before and after dental hygiene process according to PRA classifications, high risk group has been generally changed to moderate or low risk group. Conclusions : Accordingly, the supportive periodontal therapy applying dental hygiene process has been shown to be effective. The dental hygiene process in periodontal patients who require continuous management is anticipated to be a very efficient process.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 1998.12a
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• pp.84-84
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• 1998

• Proceedings of the Technology Innovation Conference
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• 1992.12a
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• pp.5-32
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• 1992

• Journal of Technology Innovation
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• v.1 no.1
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• pp.28-51
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• 1993

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.11
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• pp.718-724
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• 2014

In this work, in order to manufacture the photoelectrode of dye-sensitized solar cells, the different anatase $TiO_2$ paste was prepared by simple route using hydrothermal method. In comparison with the traditional preparing process, the hydrothermally synthesized $TiO_2$ gel was used to make paste directly. Thus, the making process was simplified and the solar conversion efficiency was improved. In comparison with 5.34% solar energy efficiency of HP-1 photoelectrode, the 6.23% efficiency of HDP-1 electrode was improved by 16.67%. This is because hydrothermally synthesized $TiO_2$ gel was used to make paste directly, the dispersibility between $TiO_2$ particles was improved and get the smoother network, leading to the charge transport ability of the electron generated in dye molecular was improved. Further, HDP-2 photoelectrode delivered the best results with Voc (open circuit voltage), Jsc (short circuit current density) FF (fill factor) and ${\eta}$(solar conversion efficiency) were 0.695 V, $15.81mA\;cm^{-2}$, 61.48% and 6.80%, respectively. In comparison with 5.34% of HP-1 photoelectrode, it was improved by 27.34%.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.23 no.2
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• pp.95-102
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• 2013

Objectives: The aim of this study is to present an appropriate sampling method for individual exposure assessment based on a comparison of toluene diisocyanate (TDI) concentrations collected through different sampling methods by work process type. Methods: Two plants handling TDIs in the Incheon area were selected. The samplings were taken during respective processes of spray painting, drying, grinding, and foaming, in which the production of TDIs took on different forms. For the sampling methods for airborne TDIs, open-face cassette holder, modified 2-piece cassette holder, and impinger were used, and the sampling was performed simultaneously at the same locations. Results: The comparison of TDI collection concentrations by each process depending on the sampling method showed high concentrations in the order of the impinger, modified 2-piece cassette holder, and open-face cassette holder for spray painting and foaming. In all processes with the exception of drying, TDI collection concentrations were higher for sampling done with the modified 2-piece cassette holder than with the open-face cassette holder. Conclusions: Based on these results, the modified 2-piece cassette holder was found to be a more appropriate sampling method than the open-face cassette holder when taking individual samples of TDIs from spray painting, grinding, and foaming processes. In particular, for individual exposure assessment of the spray painting process, which features comparatively high collection concentrations compared to the other processes, the use of a modified 2-piece cassette holder is considered appropriate.

• Structural Engineering and Mechanics
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• v.76 no.2
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• pp.175-191
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• 2020

In this study, the effect of Nano silica (SiO2) on the buckling strength of the glass fiber reinforced laminates containing the machining process causes holes were investigated. The tests have been applied on two status milled and non-milled. To promote the mechanical behavior of the fiber-reinforced glass epoxy-based composites, Nano sio2 was added to the matrix to improve and gradation. Nano sio2 is chosen because of flexibility and high mechanical features; the effect of Nanoparticles on surface serenity has been studied. Thus the effect of Nanoparticles on crack growth and machining process and delamination caused by machining has been studied. We can also imply that many machining factors are essential: feed rate, thrust force, and spindle speed. Also, feed rate and spindle speed were studied in constant values, that the thrust forces were studied as the main factor caused residual stress. Moreover, entrance forces were measured by local calibrated load cells on machining devices. The results showed that the buckling load of milled laminates had been increased by about 50% with adding 2 wt% of silica in comparison with the neat damaged laminates while adding more contents caused adverse effects. Also, with a comparison of two milling tools, the cylindrical radius-end tool had less destructive effects on specimens.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.1
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• pp.73-84
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• 1995

New morphological positioning algorithm and inspection method are presented and compared with a method by means of the Hough transform. The positioning algorithm is the process of finding the center and the rotated angle of the surface mounted device (SMD). The inspection method is capable of detecting the location of broken or bent leads. In order to obtain the center and the orientation of the SMD rapidly, the Hough transform method utilizes feature points (concave points) and is executed on a DSP board. The proposed morphological method is implemented by using the morphological skeleton subsets, and an ultimate orientation is decided by the Hit-or-Miss transform (HMT). In the inspection process, two inspection methods also are presented. The first method utilizes the morphological methods, i.e., opening and closing. It is performed before the positioning process and called an initial inspection. The second method follows the positioning process and is performed by an inspection of intersections of rulers and the lead edge (or the skeleton). It is a ruling technique which is referred to as a detailed inspection. We find the morphological approach is preciser and faster than the Hough approach by the comparison of the proposed algorithms.