• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.3
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• pp.37-46
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• 2024

This study investigates the evolution of concrete damage due to chloride-induced steel corrosion through Impact-echo (IE) testing. Three reinforced concrete specimens, each measuring 1500 mm in length, 400 mm in width, and 200 mm in thickness, were fabricated using three concrete mixture proportions of blended cement types: ordinary Portland cement, ground granulated blast-furnace slag and fly ash. Steel corrosion in the concrete was accelerated by impressing a 0.5 A current following a 35-day cycle of wet-and-dry saturation in a 3% NaCl solution. Initial IE data collected during the saturation phase showed no significant changes, indicating that moisture had a minimal impact on IE signals and highlighting the slow progress of corrosion under natural conditions. Post-application of current, however, there was a noticeable decline in both IE peak frequency and the P-wave velocity in the concrete as the duration of the impressed current increased. Remarkably, progressive monitoring of IE proves highly effective in capturing the critical features of steel-corrosion induced concrete deterioration, such as the onset of internal damages and the rate of damage propagation. These results demonstrate the potential of progressive IE data monitoring to enhance the reliability of diagnosing and prognosticating the evolution of concrete damage in marine environment.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.268-268
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• 2016

Chemical sensors have attracted much attention due to their various applications such as agriculture product, cosmetic and pharmaceutical components and clinical control. A conventional chemical and biological sensor is consists of fluorescent dye, optical light sources, and photodetector to quantify the extent of concentration. Such complicated system leads to rising cost and slow response time. Until now, the most contemporary thin film transistors (TFTs) are used in the field of flat panel display technology for switching device. Some papers have reported that an interesting alternative to flat panel display technology is chemical sensor technology. Recent advances in chemical detection study for using TFTs, benefits from overwhelming progress made in organic thin film transistors (OTFTs) electronic, have been studied alternative to current optical detection system. However numerous problems still remain especially the long-term stability and lack of reliability. On the other hand, the utilization of metal oxide transistor technology in chemical sensors is substantially promising owing to many advantages such as outstanding electrical performance, flexible device, and transparency. The top-gate structure transistor indicated long-term atmosphere stability and reliability because insulator layer is deposited on the top of semiconductor layer, as an effective mechanical and chemical protection. We report on the fabrication of InGaZnO TFTs with silver nanowire as the top gate electrode for the aim of chemical materials detection by monitoring change of electrical properties. We demonstrated that the improved sensitivity characteristics are related to the employment of a unique combination of nano materials. The silver nanowire top-gate InGaZnO TFTs used in this study features the following advantages: i) high sensitivity, ii) long-term stability in atmosphere and buffer solution iii) no necessary additional electrode and iv) simple fabrication process by spray.

• Management & Information Systems Review
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• v.39 no.2
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• pp.39-60
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• 2020

Block chain technology is one of the core elements for realizing the 4^th industrial revolution, and many efforts have been made by government and companies to provide services based on block chain technology. In this study we analyzed the benefits of block chain technology for EVMS and designed EVMS block chain platform with increased data security and work efficiency for project management data, which are important assets in monitoring progress, foreseeing future events, and managing post-completion. We did the case studies on the benefits of block chain technology and then conducted the survey study on security, reliability, and efficiency of block chain technology, targeting 18 block chain experts and project developers. And then, we interviewed EVMS system operator on the compatibility between block chain technology and EVM Systems. The result of the case studies showed that block chain technology can be applied to financial, logistic, medical, and public services to simplify the insurance claim process and to improve reliability by distributing transaction data storage and applying security·encryption features. Also, our research on the characteristics and necessity of block chain technology in EVMS revealed the improvability of security, reliability, and efficiency of management and distribution of EVMS data. Finally, we designed a network model, a block structure, and a consensus algorithm model and combined them to construct a conceptual block chain model for EVM system. This study has the following contribution. First, we reviewed that the block chain technology is suitable for application in the defense sector and proposed a conceptual model. Second, the effect that can be obtained by applying block chain technology to EVMS was derived, and the possibility of improving the existing business process was derived.

• Tuberculosis and Respiratory Diseases
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• v.61 no.2
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• pp.121-128
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• 2006

Background: The "health-related quality of life" (HRQL) for patients with chronic respiratory disease has been emphasized, because chronic respiratory disease (CRD) is chronic and progressive, and it finally causes disability. HRQL instruments may be useful for monitoring patients' progress or for determining the most appropriate choice of treatment. We describe the adapting St George's Respiratory Questionnaire (SGRQ), which is a self-administered questionnaire developed by Jones et al. (1991), into the Korean version for covering three domains of health for the patients suffering with airways disease. Method: We obtained the original SGRQ from the author after gaining permission. For adaptation, we created an expert panel and translated the original questionnaire into Korean language. The translated questionnaire was then back-translated by bilingual experts and we compared it with the original questionnaire. After correction and feasibility testing, 74 patients with chronic respiratory disease (COPD, asthma, destroyed lung) completed the Korean version of the SGRQ. The clinical status of each patients was evaluated concurrently with measurement of their health status. Result: The Korean version of the SGRQ was acceptable and easy to understand. Cronbach's alpha reliability coefficient was 0.92 for the overall scale and 0.63 for the "Symptoms", subscale, 0.87 for the "Activity", subscale, and 0.89 for the "Impacts" subscales. The correlation coefficients between the overall score and the Borg scale score, oxygen saturation, and forced expiratory volume in one second ($FEV_1$) were 0.52, -0.32 and -0.26, respectively. These results support that the Korean SGRQ was correlated with other measurements. Conclusion: The Korean SGRQ was reliable and valid for patients with chronic respiratory disease, such as COPD, asthma, and destroyed lung. The SGRQ score was well correlated with other respiratory measurements as well. Although further studies should complete the adaptation work, our results suggest that the SGRQ may be used in Korea and also for international studies involving Korean CRD patients.