• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.162-162
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• 2019

Water Distribution Network (WDN) is a critical infrastructure to be maintained ensuring proper water supply to wide-spread consumers. The WDN consists of pipes, valves, pumps and tanks, and these elements interact each other to provide adequate system performance. If elements fail by internal or external interruptions, it may result in adverse impact to water service with different degree depending on the failed element. To determine an appropriate maintenance priority, the critical elements need to be identified and mapped in the network. In order to identify and prioritize the critical elements in WDN, an element-based simulation approach is proposed, in which all the elements composing the WDN are reviewed one at a time. The element-based criticality is measured using several resilience indexes that are newly developed in this study. The proposed resilience indexes are used to quantify the impacts of element failure to water service degradation. Here, three resilience indexes are developed, such as User Demand Severity, Economic Value Loss and Water Age Degradation, each of which intends to measure different aspects of consequences, such as social, economic, and water quality, respectively. For demonstration, the proposed approach is applied to a benchmark water network to identify and prioritize the critical elements.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.2
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• pp.439-449
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• 2019

The development of information technology represented by ICBMA (IoT, Cloud, Big Data, Mobile, AI), is leading to a surge in data and a numerical and quantitative increase in data centers to accommodate it. As the data center is recognized as a social infrastructure, It is very important to identify physical security threats in advance in order to secure safety, such as responding to a terrorist attack. In this paper, we develop physical security threat breakdown structure (PS-TBS) for easy identification and classification of threats, and verify the feasibility and effectiveness of the PS-TBS through expert questionnaires. In addition, we intend to contribute to the improvement of physical security level by practical use in detailed definition on items of PS-TBS.

• Healthcare Informatics Research
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• v.24 no.4
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• pp.387-393
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• 2018

Objectives: This paper describes an experience of implementing seamless service trials online and offline by adopting Internet of Things (IoT) technology based on near-field communication (NFC) tags and Bluetooth low-energy (BLE) beacons. The services were provided for both patients and health professionals. Methods: The pilot services were implemented to enhance healthcare service quality, improve patient safety, and provide an effective business process to health professionals in a tertiary hospital in Seoul, Korea. The services to enhance healthcare service quality include healing tours, cancer information/education, psychological assessments, indoor navigation, and exercise volume checking. The services to improve patient safety are monitoring of high-risk inpatients and delivery of real-time health information in emergency situations. In addition, the services to provide an effective business process to health professionals include surveys and web services for patient management. Results: Considering the sustainability of the pilot services, we decided to pause navigation and patient monitoring services until the interference problem could be completely resolved because beacon signal interference significantly influences the quality of services. On the other hand, we had to continue to provide new wearable beacons to high-risk patients because of hygiene issues, so the cost increased over time and was much higher than expected. Conclusions: To make the smart connected hospital services sustainable, technical feasibility (e.g., beacon signal interference), economic feasibility (e.g., continuous provision of new necklace beacons), and organizational commitment and support (e.g., renewal of new alternative medical devices and infrastructure) are required.

• Safety and Health at Work
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• v.12 no.1
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• pp.42-50
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• 2021

Introduction: Despite huge investments in new technology and transportation infrastructure, terrible accidents still remain a reality of traffic. Methods: Severe traffic accidents were analyzed from four prevailing modes of today's transportations: sea, air, railway, and road. Main root causes of all four accidents were defined with implementation of the approach, based on Flanagan's critical incident technique. In accordance with Molan's Availability Humanization model (AH model), possible preventive or humanization interventions were defined with the focus on technology, environment, organization, and human factors. Results: According to our analyses, there are significant similarities between accidents. Root causes of accidents, human behavioral patterns, and possible humanization measures were presented with rooted graphs. It is possible to create a generalized model graph, which is similar to rooted graphs, for identification of possible humanization measures, intended to prevent similar accidents in the future. Majority of proposed humanization interventions are focused on organization. Organizational interventions are effective in assurance of adequate and safe behavior. Conclusions: Formalization of root cause analysis with rooted graphs in a model offers possibility for implementation of presented methods in analysis of particular events. Implementation of proposed humanization measures in a particular analyzed situation is the basis for creation of safety culture.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.6
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• pp.45-54
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• 2003

A public key certificate may be revoked before its validity period due to causes like the owner identification information change or the private key damage. Since a certificate has long valid time relatively, it is possible to become revoked during lifetime of certificate. The main technical issue in the public key infrastructure is how to handle the status of the certificate. We propose a simple mechanism for online certificate status validation that is suited to the financial network The characteristic of the proposed method is to broadcast certificate revocation information by using verifier list. The experimental results provide the same realtime as OCSP(Online Certificate Status Protocol). The proposed mechanism reduces the network load for certificate status validation in highly concentrated unbearable network.

• Structural Monitoring and Maintenance
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• v.9 no.4
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• pp.305-321
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• 2022

Bridge structural health monitoring with the aim of continuously assessing structural safety and reliability represents a topic of major importance for worldwide infrastructure managers. In the last two decades, due to their potential economic and operational advantages, drive-by approaches experienced growing consideration from researcher and engineers. This work addresses two technical topics regarding indirect frequency estimation methods: bridge and vehicle dynamics overlapping, and bridge expansion joints impact. The experimental campaign was conducted on a mixed multi-span bridge located in Lombardy using a Ford Galaxy instrumented with a mesh of wireless accelerometers. The onboard time series were acquired for a number of 10 passages over the bridge,performed at a travelling speed of 30 km/h, with no limitations imposed to traffic. Exploiting an ad-hoc sensors positioning, pitch vehicle motion was compensated, allowing to estimate the first two bridge bending frequencies from PSD functions; moreover, the herein adopted approach proved to be insensitive to joints disturbance. Conclusively, a sensitivity study has been conducted to trace the relationship between estimation accuracy and number of trips considered in the analysis. Promising results were found, pointing out a clear positive correlation especially for the first bending frequency.

• Structural Engineering and Mechanics
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• v.86 no.2
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• pp.181-195
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• 2023

To predict the rheological behaviours along with the compressive strength of self-compacting concrete that incorporates environmentally friendly ingredients as cement substitutes, a comparative evaluation of machine learning methods is conducted. To model four parameters, slump flow diameter, L-box ratio, V-funnel time, as well as compressive strength at 28 days-a complete mix design dataset from available pieces of literature is gathered and used to construct the suggested machine learning standards, SVM, MARS, and Mp5-MT. Six input variables-the amount of binder, the percentage of SCMs, the proportion of water to the binder, the amount of fine and coarse aggregates, and the amount of superplasticizer are grouped in a particular pattern. For optimizing the hyper-parameters of the MARS model with the lowest possible prediction error, a gravitational search algorithm (GSA) is required. In terms of the correlation coefficient for modelling slump flow diameter, L-box ratio, V-funnel duration, and compressive strength, the prediction results showed that MARS combined with GSA could improve the accuracy of the solo MARS model with 1.35%, 11.1%, 2.3%, as well as 1.07%. By contrast, Mp5-MT often demonstrates greater identification capability and more accurate prediction in comparison to MARS-GSA, and it may be regarded as an efficient approach to forecasting the rheological behaviors and compressive strength of SCC in infrastructure practice.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.160-160
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• 2022

Floods are the most common natural disasters and are annually causing severe destructions worldwide. Human activities, along with expected increased extreme precipitation patterns as a result of climate change enhance the future potential of floods. There are proven evidence that infrastructure based responses to flood disaster is no longer achieving optimum mitigation and have created a false sense of security. Nature-based solutions(NBS) is a widely accepted sustainable and efficient approach for disaster risk reduction and involves the protection, restoration, or management of natural and semi-natural ecosystems to tackle the climate and natural crisis. Adoption of NBS in decision-making, especially in developing nations is limited due to a lack of sufficient scenario-based studies, research, and technical knowledge. This study explores the knowledge gap and challenges on NBS adoption with case study of developing nation, specially for flood management, by the study of multiple scenario analysis in the context of climate, land-use change, and policies. Identification and quantification of the strength of natural ecosystems for flood resilience and water management can help to prioritize NBS in policymaking leading to sustainable measures for integrated flood management.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.435-439
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• 2015

It is important for Singaporean companies to manage the multifaceted risks when forming international construction joint ventures (ICJVs) with developing countries. The objectives of this study are to assess the risks associated with Singaporean ICJVs with developing countries, and investigate the risk allocation preferences in these ICJVs. To fulfill these objectives, a literature review was carried out and a questionnaire survey was performed with 38 professionals. The survey results reported "political instability" as the most critical risk, and market level risks were less critical than country and project level risks. Additionally, the results showed agreement on the risk ranking between building and infrastructure ICJVs, despite significant differences in the criticalities of five risks. Furthermore, five risks were preferably allocated to host and foreign partners, respectively, while 13 risks could be shared among partners. As few studies have explored the risk allocation preferences in ICJVs, this study expands the literature. Also, the identification of the risks allows other companies to customize their own lists of critical risks, while the preferred risk allocation provides valuable information for companies from various countries that intend to form ICJVs with developing countries. Thus, this study contributes to the global body of knowledge relating to ICJVs.

• Journal of TMJ Balancing Medicine
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• v.13 no.1
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• pp.1-12
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• 2023

Objectives: This study was performed to review the research trends in the treatment of anorexia nervosa (AN) in Traditional Chinese Medicine (TCM). Methods: Studies were searched through The China National Knowledge Infrastructure (CNKI) database. The search term for the subject were 'Eating Disorder', and 'Anorexia Nervosa'. Clinical research that conducted TCM treatment for AN patients were included. Studies were analyze according to study design, therapy method, diagnostic criteria, population and intervention. Results: 23 articles were selected. According to study design, studies were classified into two randomized controlled trial (RCT), three single group before-and-after studies, and 18 case reports. According to therapy method, they included 19 herbal medicine studies, two acupuncture treatment studies, and two complex treatment studies. The most common pattern identification was 'liver depression with spleen deficiency' (肝鬱脾虛), and the most used herb was 'Root of Bupleurum falcatum' (柴胡). Most of the studies showed effective results in increasing appetite and weight. Conclusions: The results of our study demonstrate that TCM treatments for AN has been effective in alleviating chief symptoms. However, in terms of evidence-based medicine, lack of RCT on TCM treatments for AN and absence of objective diagnostic criteria in case reports are limitations. Therefore well-designed further clinical studies should be performed based on the results of this study are recommended.