• Proceedings of the KSR Conference
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• 2002.10b
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• pp.1065-1073
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• 2002

A new damage identification technique using static displacement data is developed to assess the structural integrity of bridge structures. In the conventional damage assessment techniques using dynamic response, it is usually difficult to obtain a significant natural frequencies variation from the measured data because the natural frequencies variation is intrinsically not sensitive to the damage of a bridge. In this proposed identification method, the stiffness reduction of the bridges can be estimated using the static displacement data measured periodically and a specific loading test is not required. The static displacement data due to the dead load of the bridge structure can be measured by devices such as a laser displacement sensor. In this study, structural damage is represented by the reduction in the elastic modulus of the element. The damage factor of the element is introduced to estimate the stiffness reduction of the bridge under consideration. Finally, the proposed algorithm is verified using various numerical simulation and compared with other damage identification method. Also, the effect of noise and number of damaged elements on the identification are investigated. The results show that the proposed algorithm is efficient for damage identification of the bridges.

• Journal of the Korean Society of Safety
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• v.16 no.4
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• pp.1-6
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• 2001

An experimental study was carried out to investigate the emission characteristics of LP gas burner for the Practical combustion conditions including fm voltage, inlet area, gas Pressure, emission resistance, duct length and height. The result shows that CO is almost remains constant for the emission fan voltage, but significantly increases with the reduction rate of air inlet, up to 3000ppm at 50% of reduction rate. Also, the variation of gas pressure has no effect to CO of gas boiler due to its governor which controls gas pressure secondly, but it gives an rapid increase of CO for the gas range. The emission resistance test shows that CO is suddenly increased with the reduction rate of emission duct above 70% and main burner is stopped at 90%. The reverse wind test shows that CO is suddenly increased with the air velocity above 7m/s and main burner is stopped at 9m/s. The more horizontal length of emission duct is long and the vertical height is low, CO is infinitesimally increased.

• International Journal of Quality Innovation
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• v.2 no.2
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• pp.24-33
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• 2001

As we know, the quality of processes is technically depicted by variation, a product or process with the best quality must naturally require the variation as less as possible. The variation is usually reduced with many ways, say, by adjusting parameters settings under robust design with many turns expensive experiments. So ones are trying to reach the robustness by detecting cheap and simple methods. In this paper, a both practical and simple technique for quality improvement, namely reducing the variation, by data classification is studied. First, all possible system factors are included, which may dominate the variation law. And then we make use of the past observations and their classification as well as boxplot charts to find out the internal rule between the variation and the system factor. Next, adjust the location of the system factor according to the rule so that the variation could, to some extent, be lessened. Finally, two typical quality improvement cases based on data classification are presented.

• Applied Science and Convergence Technology
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• v.27 no.2
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• pp.35-37
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• 2018

The redox reaction on graphene nanoribbon (GNR) field effect transistors(FET) has been studied. In detail, upon employing an electrolyte gating, we verified electron transport performance modulation of GNR FET by monitoring conductance variation under oxidation and reduction processes. The conductance enhancement of GNR via removal of PMMA residue on graphene surface during redox cycles was also observed.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.669-674
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• 2002

This paper describes the properties analysis of concrete using bleeding reduction agent. According to the results, the fluidity and the air content of fresh concrete with increase of bleeding reduction agent show little difference in compare with plain concrete which does not use bleeding reduction agent. The efficiency of bleeding reduction agent is confirmed because in variation of W/C and slump, the increase of bleeding reduction agent dosage reduces bleeding remarkably. And the compressive strength of hardened concrete does not show any differences with increase the dosage of bleeding reduction agent. Bleeding reduction agent does not have bad effect on the quality of concrete such as fluidity, air content and the strength of hardened concrete and so on, the dosage of it can reduce bleeding effectively.

• International Journal of Quality Innovation
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• v.4 no.1
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• pp.148-159
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• 2003

Variation is the archenemy of quality. To reduce or control the variation in a complex production unit, firstly we need to identify the location of the root cause of the variation. This paper discusses the detection of variability and the techniques used for reduction of variation for a production unit consisting of many processes. In the first part of this paper, the background of variability detection in production systems is introduced which is then followed by a weighted network corresponding to correlation matrix of all processes. Based on the network and clustering criterion of maximum spanning tree, a classification of all processes is derived. Furthermore, the variation of each process in a class is determined by residual analysis. In the last part, the use of methods of robust design for the processes with a larger variability is discussed.

• Journal of the Semiconductor & Display Technology
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• v.7 no.4
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• pp.23-28
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• 2008

A high speed automated pitch variation unit (HAPU) related to semiconductor category sorting movement of the test handler system was developed. In the design process, 'DMADOV' step of 6-Sigma method has been applied. The design result for the desirable pitch variation was a 3:1 reduction rack-pinion and a linkage which are operated by servomotors. The realization and reliability of the mechanism was obtained at the design stage by FEM analysis, and by robust design using Taguchi orthogonal array against weight and deformation. Finally, the validity of the high speed variation mechanism was confirmed via inspection using a high speed camera while performing pitch variation.

• Korean Institute of Interior Design Journal
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• v.27 no.3
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• pp.136-144
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• 2018

The purpose of this study is to examined the unconscious response of the pupil in the observation toward the image in the eye-tracking experiments that target on a large complex cultural space. Twenty-five men participated in this experiment and the observation data were analyzed in seconds per minute on watching time. It could examine the unconscious response of information searching in the change of pupil size in the process of observing the space. The results could be defined as following several points. First, it was possible to outline the unconscious response characteristics of pupil by analyzing sudden changes in pupil size as total, cumulative, and individual. The response characteristics using frequency and time can be utilized as the analytical method to examine the degree of interest of spatial components according to the purpose of analysis in the future. Second, according to the over ${\pm}5%$ of cumulative variation rate on the pupil size change, during in the 60 seconds, the continuous pupil dilation was used 25.2 seconds in 8.8 rounds and the pupil reduction was used 18.0 seconds in 7.0 rounds. Third, when the variation rate of ${\pm}5%$ or more was regarded as the sudden changes on pupil size by individual variation, the pupil dilation was 7.2 rounds of 8.6 seconds and pupil reduction was 6.0 seconds in 5.0 rounds. This means that the pupil increases 9.3% in one expansion and decreases -8.5% in the reduction process. As regarding pupil changes as cumulative rate, it appeared high change rate on pupil reduction but it became higher on pupil dilation in individual.

• Journal of the Korean Society of Hazard Mitigation
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• v.7 no.4
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• pp.85-95
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• 2007

The variation of hydraulic and hydrologic aspect of urban area according to the strongly seasonal variation of rainfall and the increment of urbanization has caused the runoff variation and increased the flood damage, and thus made a difficulty to manage water resources in urban area. Recently, as a part of efforts to resolve these problems, the facilities for reducing runoff increasing due to urbanization have a tendency to install in our country. In this study, more effective Infiltration-Storage System(ISS) is proposed and its reducing effect is analyzed by hydraulic experimental study. The infiltration characteristics of runoff reduction facilities are examined as varying artificial rainfall and a material of infiltration layers being able to consider the influence of urban development. As a result of comparison of infiltration rate of the upper and lower parts, the infiltration rate in the lower part is larger than that of the upper part. Thus, the ISS is more available than existing runoff reduction facilities. Results obtained in this study can be provided fundamental data for improvement of existing runoff reduction facilities and practical use of ISS.

• Journal of Power Electronics
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• v.16 no.3
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• pp.1036-1045
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• 2016

This paper presents a novel control strategy for passive output filter reduction using an active output filter. The proposed method achieves the dual-function of regulating the output voltage ripple and output voltage variation during load transients. The novel control strategy allows traditional simple voltage controllers to be used, without requiring the expensive current sensors and complex controllers used in conventional approaches. The proposed method is verified with results from a 125-W forward converter.