• 한국주거학회:학술대회논문집
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• 한국주거학회 2008년도 춘계학술발표대회 논문집
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• pp.225-230
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• 2008

High-rise and high-density apartment complexes has been built and supplied on a large scale in the metropolis and metropolitan areas since 1980s in order to solve housing shortage in cities. Recently they are raising deterioration problems for aging more than 20 years. moreover, those problems show very special characters such as simultaneity and a large scale. The purpose of this study is to propose a direction for the development of the evaluating indicators to measure the level of deterioration of apartments. The level of deterioration of apartments can be evaluated by housing performance. In order to evaluate the deterioration comprehensively, the housing performance indicators should be developed on the social, economical, and physical dimension. This study analyzed the concept of the apartment deterioration and compared housing performance indicators through literature review. First of all, when considering various factors in the evaluation of the deteriorated apartments, such as evaluating ranges, attributes and dimensions, housing performance indicators should be structured with the hierarchical framework. Second, housing performance indicators evaluating the level of deterioration of apartments should include social, psychological, and cultural aspects of home environments in order to understand adequately the attitude of the middle class toward services that apartments provide. Third, in previous researches, most criteria have been developed and weighted based on only expert opinions regarding performance indicators. So, It is necessary to include residents' opinions in developing performance indicators since they can provide more practical and feasible aspects the experts could not experience or understand.

• 대한산업공학회지
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• 제33권1호
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• pp.70-75
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• 2007

This paper discusses condition based preventive replacement for deteriorating systems. The system continuouslydeteriorates in time and fails at any deterioration level which is always monitored, It is replaced at failure or atsome deteriorated level preventively before failure. The deterioration process is represented by a Weibulldistribution with a time-linear scale parameter. The cost rate function is formed considering replacement costand opportunity loss cost and deterioration dependent failure distribution, If the system has an increasingdeterioration dependent failure rate, the optimal deterioration level for preventive replacement can be determinedfrom minimizing the cost rate. An illustrative example is given for a Weibull deterioration dependent failuredistribution.

• 한국도로학회논문집
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• 제19권5호
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• pp.1-11
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• 2017

PURPOSES : This study is aimed at development of a stochastic pavement deterioration forecasting model using National Highway Pavement Condition Index (NHPCI) to support infrastructure asset management. Using this model, the deterioration process regarding life expectancy, deterioration speed change, and reliability were estimated. METHODS : Eight years of Long-Term Pavement Performance (LTPP) data fused with traffic loads (Equivalent Single Axle Loads; ESAL) and structural capacity (Structural Number of Pavement; SNP) were used for the deterioration modeling. As an ideal stochastic model for asset management, Bayesian Markov multi-state exponential hazard model was introduced. RESULTS:The interval of NHPCI was empirically distributed from 8 to 2, and the estimation functions of individual condition indices (crack, rutting, and IRI) in conjunction with the NHPCI index were suggested. The derived deterioration curve shows that life expectancies for the preventive maintenance level was 8.34 years. The general life expectancy was 12.77 years and located in the statistical interval of 11.10-15.58 years at a 95.5% reliability level. CONCLUSIONS : This study originates and contributes to suggesting a simple way to develop a pavement deterioration model using the total condition index that considers road user satisfaction. A definition for level of service system and the corresponding life expectancies are useful for building long-term maintenance plan, especially in Life Cycle Cost Analysis (LCCA) work.

• Asian-Australasian Journal of Animal Sciences
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• 제28권6호
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• pp.816-826
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• 2015

The present experiment evaluated the influence of moisture level and anaerobic fermentation on aerobic stability of total mixed ration (TMR). The dynamic changes in chemical composition and microbial population that occur after air exposure were examined, and the species of yeast associated with the deterioration process were also identified in both non-fermented and fermented TMR to deepen the understanding of aerobic deterioration. The moisture levels of TMR in this experiment were adjusted to 400 g/kg (low moisture level, LML), 450 g/kg (medium moisture level, MML), and 500 g/kg (high moisture level, HML), and both non-fermented and 56-d-fermented TMR were subjected to air exposure to determine aerobic stability. Aerobic deterioration resulted in high losses of nutritional components and largely reduced dry matter digestibility. Non-fermented TMR deteriorated during 48 h of air exposure and the HML treatment was more aerobically unstable. On dry matter (DM) basis, yeast populations significantly increased from $10^7$ to $10^{10}cfu/g$ during air exposure, and Candida ethanolica was the predominant species during deterioration in non-fermented TMR. Fermented TMR exhibited considerable resistance to aerobic deterioration. Spoilage was only observed in the HML treatment and its yeast population increased dramatically to $10^9cfu/g$ DM when air exposure progressed to 30 d. Zygosaccharomyces bailii was the sole yeast species isolated when spoilage occurred. These results confirmed that non-fermented and fermented TMR with a HML are more prone to spoilage, and fermented TMR has considerable resistance to aerobic deterioration. Yeasts can trigger aerobic deterioration in both non-fermented and fermented TMR. C. ethanolica may be involved in the spoilage of non-fermented TMR and the vigorous growth of Z. bailii can initiate aerobic deterioration in fermented TMR.

• 한국농공학회논문집
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• 제58권3호
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• pp.81-90
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• 2016

It is significant to redevelop the deterioration reservoir through raising for countermeasure to climate change and Earthquake improvement of reservoir. This study aims to investigate the behavior of deterioration reservoir with poor-fabricated core subjected to raising water level and earthquake using numerical analysis. From the analysis results, water level raising and earthquakes induce crack and subsidences at the crown and the front side of deterioration reservoir. For the reinforcement of the deterioration reservoir is required appropriate measures method and raised method suitable, drainage and slope protection method judged to be necessary.

• 한국주거학회논문집
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• 제20권6호
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• pp.89-99
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• 2009

The purpose of this research is to determine the deterioration characteristics of high-rise and high-density apartment complexes in 1st period new towns in order to regenerate apartments as sustainable residential environments in Korea. For this purpose, the level of deterioration was evaluated by using 'evaluating indicators of the level of deterioration of high-rise and high-density apartments'. The deterioration characteristics were determined inclusively and concretely based on evaluation results. In addition, the deterioration level according to residents' awareness of the deterioration of their apartment was evaluated. This study was conducted by methods of field data collection, staff interview, field measurement, and resident survey according to the measurement of the evaluating indicators. And the re-organized questionnaire based on the evaluating indicators was utilized for a survey of resident's awareness. The results are as follows: In the physical dimensions of apartments, the deterioration characteristics included deteriorated equipment and a decline in structural performance due to the aging of the apartment, a shortage of parking spaces, and the low flexibility of the bearing wall structure, etc. In terms of the social dimensions, the apartments showed an increase in the number of elderly households, a shortage of community facilities, and a lack of the opportunity for community participation etc. In terms of the economic dimensions, the apartments showed limitations in maintenance & repair and a lack of environmentally friendly features.

• 한국주거학회논문집
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• 제20권4호
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• pp.131-142
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• 2009

High-rise and high-density apartment complexes have been built and supplied on a large scale in the 1st period of the New Town project in metropolitan areas since the late 1980s. Now It has become necessary to improve those apartment complexes, which have serious deterioration problems for aging more than about 20 years accompanying simultaneity and a large scale. The purpose of this research is to develop the evaluating indicators to measure the level of deterioration of apartments inclusively and practically in order to regenerate apartments as sustainable residential environments. This study is composed of the following four parts; (a) establishing the conceptual model of evaluation of apartment deterioration, (b) selecting evaluation items, (c) constituting evaluation measurement, and（ｄ)weighting evaluation indicators. First, deterioration of apartments was conceptualized by physical. social, and economical aspects in terms of sustainable development and proposed the conceptual model of hierarchy structure of evaluation of apartment deterioration by literature reviews. Second, evaluating items were selected based on literature reviews of existing indicators and preceding studies about apartments of Korea and foreign countries. The evaluating indicators were identified as a total of 77 evaluating items which were composed of three dimensions and 9 attributes on the basis of the conceptual model. They cover comprehensive scope of the apartment such as unit, building, complex, and site. Third, as the measurement, the 5 point ordinal scale measure was suggested. The evaluating measurement including measure standards, measure methods, and measure contents were developed by each evaluating items. Lastly, the weighting of evaluating indicators was analyzed by AHP method conducted by survey on the expert group. Items were identified as high contributors or low contributors. The weighting of these items could suggest several evaluations according to the situation. The evaluation of the level of deterioration can be done by both total evaluation and a specific field of evaluation. In addition, it is easy to grasp deteriorated attributes or dimensions by providing a radar and bar chart showing evaluation results. These evaluating indicators could be a useful tool to grasp actual methods for the regeneration of apartments.

• Earthquakes and Structures
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• 제24권5호
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• pp.333-343
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• 2023

Various seismic isolation and reduction devices have been applied to suppress the longitudinal vibration of continuous girder bridges. As representative devices, lead rubber bearing (LRB) and fluid viscous damper (FVD) might suffer from deterioration during the long-term service. This study aims to evaluate the impact of device deterioration on the seismic responses of continuous girder bridges and investigate the seismic behavior of deteriorated LRBs and FVDs. Seismic performance of a simplified bridge model was investigated, and the influence of device deterioration was evaluated by the coefficient of variation method. The contribution of LRB and FVD was assessed by the Sobol global sensitivity analysis method. Finally, the seismic behaviors of deteriorated LRBs and FVDs were discussed. The result shows that (i) the girder-pier relative displacement is the most sensitive to the changes in the deterioration level, (ii) the deterioration of FVD has a greater effect on the structural responses than that of LRB, (iii) FVD plays a major role in energy dissipation with a low degradation level while LRB is more essential in dissipating energy when suffering from high degradation level, (iv) the deteriorated devices are more likely to reach the ultimate state and thus be damaged.

• 한국수자원학회논문집
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• 제55권spc1호
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• pp.1167-1175
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• 2022

본 연구에서는 노후도를 보다 간단히 평가할 수 있는 운영지수 분석법을 개발하였고 이를 기존의 노후도 분석법과 비교 분석하였다. 청주시 상수관망에 적용하여 노후도를 비교 분석하였으며 사용성을 입증하였다. 기존의 간접평가법 분석결과, 율량동(구시가지), 내덕1동, 용암2동 상수관망의 노후도가 가장 높은 것으로 분석되었으며, 신뢰성해석을 통한 안전도 분석 결과 내덕1동 상수관망이 직경 200 mm, 300 mm 강관 모두 파괴확률 3.21%, 4.65%로 안전도가 가장 취약한 것으로 분석되었다. 운영지수 분석법의 경우, 내덕1동 상수관망이 직경 200 mm, 300 mm 강관 모두 위험도 0.2609, 0.2644로 가장 높은 것으로 분석되었으며, 개량 우선순위는 비슷한 것으로 나타났다. 따라서 향후 운영지수 분석법을 통해 상수도관을 보다 간단하게 노후도를 분석하여 상수관망의 운영관리에 활용이 가능할 것으로 판단된다.

• Tribology and Lubricants
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• 제26권2호
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• pp.111-121
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• 2010

The purpose of this study is to examine the effect of diesel soot contents on the deterioration of engine oil in terms of the changes in the dielectric constants of diesel engine oils. Therefore, it is figured out the level of oil deterioration by investigating how are the dielectric constants of diesel engine oils changed according to changes in diesel soot contents. The measured data will be able to be used as the reference data to judge the level of oil deterioration induced by diesel soot when the previously developed oil deterioration sensor will be applied at diesel vehicles in the future.