• Geomechanics and Engineering
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• 제19권6호
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• pp.499-511
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• 2019

The reliability of reinforced concrete structures is frequently compromised by the deterioration caused by reinforcement corrosion. Evaluating the effect caused by reinforcement corrosion on structural behaviour of corrosion damaged concrete structures is essential for effective and reliable infrastructure management. In lifecycle management of corrosion affected reinforced concrete structures, it is difficult to correctly assess the lifecycle performance due to the uncertainties associated with structural resistance deterioration. This paper presents a stochastic deterioration modelling approach to evaluate the performance deterioration of corroded concrete structures during their service life. The flexural strength deterioration is analytically predicted on the basis of bond strength evolution caused by reinforcement corrosion, which is examined by the experimental and field data available. An assessment criterion is defined to evaluate the flexural strength deterioration for the time-dependent reliability analysis. The results from the worked examples show that the proposed approach is capable of evaluating the structural reliability of corrosion damaged concrete structures.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1522-1528
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• 2007

Electric Power cable is the apparatus that receives electric power from the Korea Electric Power Corporation and supplies electric power to electric train and annex facilities of each railway station. With substantial ripple effect during power blackout accidents, such power blackout accidents must be coped with by discriminating the status of insulation deterioration of electric power cable in advance. Discrimination of insulation deterioration of the electric power cable is normally executed while the power is disconnected and it is very difficult to discover, at early stage, the insulation deterioration of the power cable in operational state since the duration of inspection is limited. This research aims to consider method of diagnosing the insulation deterioration of electric power cable in On-Line state rather than diagnosis in Off-Line state in order to secure reliability of power supply by reducing duration of power blackout (accidental blackout and blackout during works) and by seeking reduction in equipment and manpower used in diagnosis of deterioration through prevention of the accident itself prior to occurrence through early restoration of accident due to insulation deterioration of the electric power cable and assessment of performance of the cable under operation.

• 기본간호학회지
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• 제18권3호
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• pp.317-327
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• 2011

Purpose: The purpose of this study was to contribute data toward prevention from advancing dementia and also prevention of deterioration in cognitive impairment by constructing an optimal prediction model and verifying factors influencing cognitive impairment in elders with dementia who reside at home. Methods: The participants in this study were 351 elders who were registered at dementia day care centers in 11 regions of Metropolitan Incheon. Collected data were analyzed using SPSS Statistics 17.0 and SAS 9.1. Bootstrap method using the Clementine program 12.0 was applied to build an optimum prediction model. Results: Gender and education (general characteristics), alcohol, urinary/fecal incontinence, exercise, weight, and ADL (state of health), and depression (psychological state) were found to have an affect on cognitive impairment in these elders. Conclusion: Study results indicate nine key factors that affect cognitive impairment of elders with dementia who reside at home and that could be useful in prevention and management nursing plans. These factors could also be used to expand the role of nurses who are working in community day care centers, and can be applied in the development and provision of various programs to aid retention and improve cognitive function as well as preventing deterioration of cognition.

• 디지털융복합연구
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• 제20권4호
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• pp.651-659
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• 2022

본 연구의 목적은 코로나19로 인한 가정경제 악화가 조손가정 청소년의 정신건강에 미치는 영향을 파악하는 것이다. 이를 위해 본 연구는 질병관리청에서 구축한 2020년 제16차 청소년건강행태조사의 원자료를 활용하여 코로나19로 인한 가정경제 악화 여부가 조손가정 청소년의 불안, 스트레스, 우울, 자살생각에 미치는 영향을 분석하였다. 연구질문에 대한 주요 결과는 다음과 같다. 첫째, 589명의 조손가정 청소년 중 39%가 코로나19로 인한 가정경제 악화를 경험했다. 또한 가정경제 악화를 경험한 청소년이 그렇지 않은 청소년에 비해 불안과 스트레스의 점수가 높았고, 우울과 자살생각의 경험 비율이 높았다. 둘째, 회귀분석 결과, 조손가정 청소년의 코로나19로 인한 가정경제 악화의 경험은 불안, 스트레스, 우울, 자살생각에 통계적으로 유의미한 정적 영향을 미쳤다. 본 연구의 분석 결과를 기반으로 코로나19와 같은 재난 상황에서 조손가정 청소년의 정신건강을 보호하기 위한 방안을 논의하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.739-744
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• 2001

In this study, experimental research was carried out to develop protective finishing, coating materials and new hybrid technique for deteriorating prevention and high durability in concrete structures. It had sufficiently recommended performance for the protective finishing method of concrete structures through testings. This is more progressive double membrane method than single membrane type designed by conventional method. It was found that this hybrid construction method had very excellent performance to improve the durability of existing concrete structures and attain the beauty of concrete structures.

• 한국안전학회지
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• 제17권2호
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• pp.69-75
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• 2002

Current fire safety in the construction sites has developed piecemeal over a considerable period of time. However, the law and regulation of fire safety is insufficient to protect fro in the construction sites. The frequency of fire in the construction sites is very rare but it brings longterm deterioration durability of building structure and large scale industrial calamity. There are many process of works and each work deals with many kind of flammable material, so it is very difficult to find a proper safety fire prevention. This study executed the questionnaire and fire experiment of the welding work to provide effective fire prevention counterplan.

• 한국농공학회지
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• 제65권3호
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• pp.32-39
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• 2023

• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1450-1458
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• 2018

Commutation failures can deteriorate the availability of high-voltage direct current (HVDC) links and may lead to outage of the HVDC system. Most commutation failures are caused by voltage reduction due to ac system faults on inverter side. The commutation failure process can be divided into two stages. The first stage, from the occurrence to the clearing of faults, is called 'Deterioration Stage'. The second stage, from the faults clearing to restoring the power system stability, is called 'Recovery Stage'. Based on the analysis of the commutation failure process, this paper proposes a direct-current fuzzy controller including prevention and recovery controller. The prevention controller reduces the direct current to prevent Commutation failures in the 'Deterioration Stage' according to the variation of ac voltage. The recovery controller magnifies the direct current to speed up the recovery of power system in the 'Recovery Stage', based on the recovery of direct voltage. The validity of this proposed fuzzy controller is further proved by simulation with CIGRE HVDC benchmark model in PSCAD/EMTDC. The results show the commutation failures can be mitigated by the proposed direct-current fuzzy controller.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2003년도 Proceeding
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• pp.141-148
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• 2003

Customer retention is a common concern for many industries and a critical issue for the survival in today's greatly compressed marketplace. Current customer retention models only focus on detection of potential defectors based on the likelihood of defection by using demographic and customer profile information. In this paper, we propose a dynamic procedure for defection detection and prevention using past and current customer behavior by utilizing SOM and Markov chain. The basic idea originates from the observation that a customer has a tendency to change his behavior (i.e. trim-out his usage volumes) before his eventual withdrawal. This gradual pulling out process offers the company the opportunity to detect the defection signals. With this approach, we have two significant benefits compared with existing defection detection studies. First, our procedure can predict when the potential defectors could withdraw and this feature helps to give marketing managers ample lead-time for preparing defection prevention plans. The second benefit is that our approach can provide a procedure for not only defection detection but also defection prevention, which could suggest the desirable behavior state for the next period so as to lower the likelihood of defection. We applied our dynamic procedure for defection detection and prevention to the online gaming industry. Our suggested procedure could predict potential defectors without deterioration of prediction accuracy compared to that of the MLP neural network and DT.

• 대한안전경영과학회지
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• 제12권4호
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• pp.53-60
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• 2010

When a fire breaks out, it is difficult to find out the causes of the fire, because combustible things around fire scene are usually burnt away. Among many causes of fires are electronic wires, this thesis deal with the destroyed sheath of electronic wires caused by fire. It was studied with the use of measurement devices focusing on the distinctions of wires and conductors. This study especially emphasized the process of deterioration, burning pattern, and composition of electronic wire conductor. It also has a phenomenological approach to the distinctive cause of fire by some partial force. The fire prevention methods have been suggested through the analysing results of fire patterns. This study is expected to be a useful material for analyzing various electrical fires.