• 한국구조물진단유지관리공학회 논문집
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• 제6권2호
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• pp.145-155
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• 2002

It is essential for health monitoring of a cable-stayed bridge to provide more accurate and enough information from the sensors. In experimental modal testing, the chosen measurement locations and the number of measurements have a major influence on the quality of the results. The choice is often difficult for complex structures like a cable-stayed bridge. It is extremely important a cable-stayed bridge to minimize the number of sensing operations required to monitor the structural system. In order to obtain the desired accuracy for the structural test, several issues must take into consideration. Two important issues are the number and location of response sensors. There are usually several alternative locations where different sensors can be located. On the other hand, the number of sensors might be limited due to economic constraints. Therefore, techniques such as methodologies, algorithms etc., which address the issue of limited instrumentation and its effects on resolution and accuracy in health monitoring systems are paramount to a damage diagnosis approach. This paper discusses an optimum sensor placement criterion suitable to the identification of structural damage for continuous health monitoring. A Kinetic Energy optimization technique and an Effective Independence Method are analyzed and numerical and theoretical issues are addressed for a cable-stayed bridge. Its application to a cable-stayed bridge is discussed to optimize the sensor placement for identification and control purposes.

• Smart Structures and Systems
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• 제21권2호
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• pp.171-185
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• 2018

Maintenance of deteriorated bridge structures has always been one of the challenging issues in developing countries as it is directly related to daily life of people including trade and economy. An effective maintenance strategy is highly dependent on timely inspections on the bridge health condition. This study is intended to investigate an approach for detecting bridge damage for the long-term health monitoring by use of copula theory. Long-term measured data for the seven-span plate-Gerber bridge is investigated. Autoregressive time series models constructed for the observed accelerations taken from the bridge are utilized for the computation of damage indicator for the bridge. The copula model is used to analyze the statistical changes associated with the modal parameters. The changes in the modal parameters with the time are identified by the copula statistical properties. Applicability of the proposed method is also discussed based on a comparison study among other approaches.

• Nuclear Engineering and Technology
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• 제52권10호
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• pp.2262-2273
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• 2020

Digital twin technology can provide significant value for the prognostics and health management (PHM) of critical plant components by improving insight into system design and operating conditions. Digital twinning of systems can be utilized for anomaly detection, diagnosis and the estimation of the system's remaining useful life in order to optimize operations and maintenance processes in a nuclear plant. In this regard, a conceptual framework for the application of digital twin technology for the prognosis of Control Element Drive Mechanism (CEDM), and a data-driven approach to anomaly detection using coil current profile are presented in this study. Health management of plant components can capitalize on the data and signals that are already recorded as part of the monitored parameters of the plant's instrumentation and control systems. This work is focused on the development of machine learning algorithm and workflow for the analysis of the CEDM using the recorded coil current data. The workflow involves features extraction from the coil-current profile and consequently performing both clustering and classification algorithms. This approach provides an opportunity for health monitoring in support of condition-based predictive maintenance optimization and in the development of the CEDM digital twin model for improved plant safety and availability.

• 웰빙융합연구
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• 제7권1호
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• pp.27-33
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• 2024

Purpose: This study investigates human error accidents in the Korean railway sector, emphasizing the need for systematic management to prevent such incidents, which can have fatal consequences, especially in driving-related jobs. Research design, data and methodology: This paper analyzed data from the Aviation and Railway Accident Investigation Board and the Korea Transportation Safety Authority, examining 240 human error accidents that occurred over the last five years (2018-2022). The analysis focused on accidents in the driving, facility, electric, and control fields. Results: The findings indicate that the majority of human error accidents stem from negligence in confirmation checks, issues with work methods, and oversight in facility maintenance. In the driving field, errors such as signal check neglect and braking failures are prevalent, while in the facility and electric fields, the main issues are maintenance delays and neglect of safety measures. Conclusions: The paper concludes that human error accidents are complex and multifaceted, often resulting from a high workload on engineers and systemic issues within the railway system. Future research should delve into the causal relationships of these accidents and develop targeted prevention strategies through improved work processes, education, and training.

• 대한치과의사협회지
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• 제50권1호
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• pp.6-12
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• 2012

As in all other parts in the body, oral tissue also undergoes dramatic changes with increasing age. Since these changes occasionally go beyond physiological scope, which may result in pathological changes, it is essential for dentist to understand changes caused by normal aging process. With increasing age, tooth morphology and occlusion also varies, especially loss of hard tissue, which is taking place in lifelong time, occurs as a result of tooth wear. When this loss of hard tissue is presented rapidly or excessively, functional and esthetical problems are raised, resulting in lowering quality of life of patient as well as making dental treatment for oral rehabilitation even more complex. Therefore, based on understanding of change in occlusion with increasing age, strategic approaches for maintenance of oral health in both functional and esthetic aspect are required as appropriate restoration and maintenance for progressive tooth wear enables desirable occlusal relationship. Carefully planned-restorative treatment in accordance with changed occlusal relationship is also required in the same context. Instead of taking changes in oral tissue as only a consequence of ageing, it is vital to educate patient and his or her guardian, assuring maintenance of oral hygiene and regular dental check-up are of utmost importance for improved oral health.

• 한국건설관리학회논문집
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• 제8권5호
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• pp.132-141
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• 2007

BTL 사업 대상 중 교육시설물은 교육인적자원부에 따르면 2007년까지 3개년에 걸쳐 13조원 이상 규모의 BTL 민간투자 사업을 발주하기로 하는 등 교육시설물의 건설은 국내 공공시설물 건설 사업에서 큰 비중을 점하고 있다. 본 연구에서는 교육시설물 BTL 사업의 비용 항목 중 운영관리비에 해당되는 위생관리비 산정 방법을 제시하였다. 또한 이를 바탕으로 유지관리 시스템의 주요 모듈을 개발하고, 개발된 모델의 타당성을 입증하기 위해 대안별 비용의 비교 분석을 실시하였다.

• 한국농촌간호학회지
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• 제5권1호
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• pp.33-39
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• 2010

Purpose: This study was done to identify change in self-concept of smoking experience in middle school students. Method: The study was a longitudinal survey design and used only the responses on self-concept and smoking state from the data of the Korea Youth Panel Survey (KYPS). The sample for this study consisted of 3,449 middle school students and the data were collected over a two-year period (2003-2004). Results: Self-esteem scores for the first and second year were significantly higher and self-stigma and aggression scores were significantly lower in the non-smoking maintenance group. There was a significant increase in self-esteem scores for students in second year who quit smoking compared to those in first year. There was a significant decrease in scores for attachment to surrounding people and emotional sense of control in second year students compared to those first year for students in the non-smoking maintenance group and the group that quit smoking. Self-intimacy scores were significantly lower in the smoking maintenance group. There was a significant increase in sex-role identity scores in second year students compared to those in first year for students in the group who newly started smoking. Conclusion: Findings from this study can contribute to designing appropriate smoking prevention strategies to improve self-constructs related smoking experiences in adolescents.

• 한국구조물진단유지관리공학회 논문집
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• 제20권6호
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• pp.1-9
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• 2016

본 논문은 교량의 예방적 유지관리 효과를 생애주기비용 절감 측면에서 분석 하였다. 예방적 유지관리는 현재 실시되고 있는 대응적 유지관리 전략과 대비 되는 유지관리 전략으로 교량의 열화지연을 통해 궁극적으로는 교량의 사용수명을 연장 시키며 생애주기비용을 절감시키는 유지관리 전략이다. 이러한 예방적 유지관리 효과를 분석하기 위해 교량의 공용연수에 따른 건전도 점수 변화 모델과 FHWA 자료를 바탕으로 한 국내 고속도로 교량의 건전도 점수에 따른 보수 보강 비용 모델을 제시 하였다. 제시한 복수의 모델과 국내외 참고 문헌을 바탕으로 제안된 예방적 유지관리 항목(청소와 도장)의 비용과 주기를 활용하여 사용수명 100년까지의 표준교량($1,730m^2$/교량) 당 생애주기 비용과 향후 20년간의 고속도로 총 유지관리 비용을 산정 하였다. 분석 결과 100년간 예방적 유지관리 활동으로 인해 교량 당 5억원의 절감효과를 볼 수 있으며 현재 예방적 유지관리 활동을 실시할 경우 20년 후(2035년)에는 총 1,837억원, 즉 연간 약 92억원의 비용 절감효과를 볼 수 있는 것으로 분석 되었다.

• 대한치과의사협회지
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• 제55권1호
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• pp.90-95
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• 2017

As residual ridge resorption occurs, complete dentures tend to become loose. Denture relining and rebasing are an essential element for improving a denture's stability and prevention side effect such as sore spot, epulis fissuratum. This paper focuses about health insurance is available for maintenance of complete denture and, methods of relining or rebasing.

• 한국주거학회논문집
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• 제15권4호
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• pp.65-74
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• 2004

As the advent of an aging society, housing for the elderly has been of great concern. Because the majority of the elderly prefers living in their own familiar homes rather than moving to new ones, this study is concerned with the ways use and maintenance of the existing houses from the viewpoint of their independent living. The data was analyzed with frequency, percentage, mean, correlation, and multiple regression by using the SPSS 10.0 for Windows. The findings from the study were: Needs for Affordance of interior design(AID) were required slightly above the average. Among the items of AID, physiological maintenance was the most demanding, and social facilitation, behavioral facilitation, and perceptual maintenance were sequentially followed in the level of needs. The elements that should be considered in housing environment plans for the elderly household ire: (a) use of slip-proof tiles for the floor of the bathroom, (b) installation of safety bars in the bathroom, and (c) installation of emergency buttons. It also turned out that educational levels and health status were the most significant factors on the needs for AID.