• 한국항공운항학회지
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• 제27권4호
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• pp.105-113
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• 2019

The commercial pilot retirement age has continued to 65 since the International Civil Aviation Organization(ICAO) amended the recommended age limit from 60. The target of this review is to analyse whether aged pilots have an increased age-dependent risk of medical incapacitation. Medical in-flight incapacitation is actually very rare event and the demonstrated annual incapacitation rate provides an acceptable risk within the criteria known as 1% safety rule for a pilot undertaking air transport operations while some controversies exist. There is a possibility that the accident rate has decreased due to the improved skill by increasing pilot's age. At the decision of flight or not for elderly airline pilot the interacting factors of personal health status, piloting experience and new flight environments should be considered to define job limit criteria than mere the age. Results of a survey led by airline pilot association in Korea shows 65% of airline pilots are willing to fly without any age limit and 87% agreed that age limit is worthy to extend beyond current standard on the basis of medical examinations. Only 11% agreed to maintain current age limit.

• 한국생활과학회지
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• 제20권3호
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• pp.713-729
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• 2011

The purpose of this study is to suggest an activation plan for community centers. The community centers, categorized into 3 types by the number of visitors, were comparatively analyzed by their programs, operation, and visitors' opinion. 6 community centers in Heungduk-gu, Cheongju-city, their 6 operators, and their 220 visitors were the sample. This study surveyed community centers on the spot about their space characteristics and programs, interviewed operators, and asked questionnaires to visitors. The data of the 3 categorized centers were analyzed by frequency, average, and percentage. The following is the result: 1) The number of visitors was dependent on the type of residence and age of the residents. The activated community centers were found in residence type apartment blocks, and with an age group in its 40s. 2) The space satisfaction was dependent on the year of construction; it was higher with newer buildings and wider sizes. 3) All the centers were affirmative on the communication of the participants of programs. In conclusion, the activation plan of the community center has to comprise a renovation of old buildings, public promotion, and the development of programs taking into consideration the age group of the residents.

• Nuclear Engineering and Technology
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• 제56권2호
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• pp.526-535
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• 2024

This paper proposes a safety-critical standby component unavailability model that contains aging effects caused by the elapsed time from installation, component degradation due to surveillance tests, and imperfect maintenance actions. An application of the model to a Motor-Operated Valve and a Motor-Driven Pump involved in the HPIS of a VVER/1000-V446 nuclear power plant is demonstrated and compared with other existing models at component and system levels. In addition, the effects of different unavailability models are reflected in the NPP's risk criterion, i.e., core damage frequency, over five maintenance periods. The results show that, compared with other models that do not simultaneously consider the full effects of degradation and maintenance impacts, the proposed model realistically evaluates the unavailabilities of the safety-related components and the involved systems as a plant age function. Therefore, it can effectively reflect the age-dependent CDF impact of a given testing and maintenance policy in a specified time horizon.

• 한국품질경영학회:학술대회논문집
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• 한국품질경영학회 1998년도 The 12th Asia Quality Management Symposium* Total Quality Management for Restoring Competitiveness
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• pp.269-276
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• 1998

This paper proposes an opportunistic age replacement policy. The system has two types of failures. Type I failures (minor failures) are removed by minimal repairs, whereas type II failures are removed by replacements. Type I and type II failures are age-dependent. A system is replaced at type II failure (catastrophic failure) or at the opportunity after age T, whichever occurs first. The cost of the minimal repair of the system at age z depends on the random part C(z) and the deterministic part c(z). The opportunity arises according to a Poisson process, independent of failures of the component. The expected cost rate is obtained. The optimal $T^{\ast}$ which would minimize the cost rate is discussed. Various special cases are considered. Finally, a numerical example is given.

• Imaging Science in Dentistry
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• 제30권4호
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• pp.235-242
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• 2000

Purpose: To evaluate the effect of the systemic osteoporosis on radiographic density of alveolar bone and cortical thickness of mandible. Materials and Methods: The bone mineral density values of lumbar and femur were measured by dual-energy X-ray absorptiometry and T scores of lumbar, femur were obtained respectively. Radiographic densities of alveolar bones and panorama mandibular index (PMI, represents as cortical thickness) were analysed statistically according to age and T score variables. Results: The radiographic density of alveolar bone of maxillary molar showed significant difference by age and femur T group. That of mandibular molar showed significant difference between femur T group. Panorama mandibular index showed significant difference between age groups. Conclusion: The radiographic density of alvealar bones was more dependent on age and femur T than lumbar T. Cortical thickness of mandible was correlated with increasing age.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.591-594
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• 2005

Concrete structure that has been constructed in real field is on multi-axial stress state condition. After placing of concrete, hydration heat and shrinkage of concrete can cause various stress conditions with respect to the restraint level and condition. So, to predict the early age behavior of concrete structure, multi-axial material model is required and microplane model is acceptable. Recently, many studies have been performed on the microplane model, but the model developed up to now has been related to hardened concrete that material property is constant with concrete age. So, it is inappropriate to apply this model immediately to analyze the early age behavior of concrete. In this study, microplane model that can predict early age behavior of concrete was developed and cracking analysis using that was performed to describe cracking behavior for massive concrete sturucture.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권2호
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• pp.142-148
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• 2005

This paper proposes a cell age model for Penicillium chrysogenum fed-batch cultivation to supply a qualitative insight into morphology-associated dynamics. The average ages of the segregated cell populations, such as growing cells, non-growing cells and intact productive cells, were estimated by this model. A combined model was obtained by incorporating the aver-age ages of the cell sub-populations into a known but modified segregated kinetic model from literature. For simulations, no additional effort was needed for parameter identification since the cell age model has no internal parameters. Validation of the combined model was per-formed by 20 charges of industrial-scale penicillin cultivation. Meanwhile, only two charge-dependent parameters were required in the combined model among approximately 20 parameters in total. The model is thus easily transformed into an adaptive model for a further application in on-line state variables prediction and optimal scheduling.

• Journal of Yeungnam Medical Science
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• 제13권2호
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• pp.261-271
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• 1996

저자들은 1992년 1월 1일부터 1995년 6월 30일까지 영남대학병원에서 양에너지 방사선 골밀도 측정기로 요추 골밀도를 측정한 자연적 폐경기 여성 136명을 대상으로 설문과 의무기록지를 검토하여 연령, 신장, 체중, 초경 및 폐경 연령, 자녀수, 모유수유 자녀수, 경구 피임력, 골다공증의 가족력, 우유 및 커피섭취량, 흡연 및 음주력 그리고 신체활동량을 평가하였다. 평균 연령은 55.2세였고, 평균 폐경 연령은 47.9세였다. 골밀도는 신장, 체중 그리고 신체활동량과 유의한 양의 상관관계를 보였고, 나이, 폐경 후 기간 그리고 자녀수와는 유의한 음의 상관관계를 보였다. % age-matched 골밀도는 나이, 신장, 체중, 신체활동량 그리고 폐경 후 기간과 유의한 상관관계를 보였다. 골밀도를 종속변수로 한 다중회귀분석에서는, 폐경 후 기간, 신체활동량 그리고 체중이 골밀도에 영향을 주는 유의한 변수였고, 그 중 폐경 후 기간이 가장 영향을 주는 변수였다. 나이의 효과를 통제하기 위해 % age-matched 골밀도를 종속변수로 한 다중회귀분석에서는, 신체활동량과 체중이 % age-matched 골밀도에 영향을 주는 유의한 변수였고, 신체활동량이 가장 영향을 주는 변수였다. 그 결과 폐경기 여성의 골밀도에 영향을 미치는 인자들 중 나이의 영향을 배제하면 신체활동량과 체중이 중요한 인자로 생각된다. 그러므로 지속적인 신체활동이 골다공증의 예방에 중요하다는 것을 알 수 있었다.

• 한국도로학회논문집
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• 제16권6호
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• pp.59-67
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• 2014

PURPOSES : The purpose of this study is to analyse the longitudinal steel strain and stress of continuously reinforced concrete pavement(CRCP) with longitudinal and transverse direction at early age using stress dependent strain analysis method. METHODS : To measure the longitudinal steel strain, 9-electrical resistance and self-temperature compensation gauges were installed to CRCP test section (thickness = 250mm, steel ratio = 0.7%) and continuously measured 10min. intervals during 30days. In order to properly analyze the steel stress first, temperature compensation process has been conducted. Secondly, measured steel strains were divided into stress dependent strain (elastic strain) and stress independent strain (thermal strain) and then stress dependent strain was applied to stress calculation of longitudinal steels. RESULTS : Steel strains were successfully measured during 30days. To verify the accuracy of temperature compensation process, measured coefficient of thermal expansion(COTE,$11.46{\times}10^{-6}m/m/^{\circ}C$) of longitudinal steel before paving was compared with that of unrestrained steel. Max. steel stress in the transverse direction shows about 266MPa at 23days after placement. CONCLUSIONS : Steel stresses in the longitudinal and transverse direction have been evaluated. In longitudinal direction, steel stress from the crack was rapidly reduced from 183MPa at crack to 18MPa from 600mm apart the crack. From this observation, stress effective length can be identified as within 600mm apart from the crack. In transverse direction, max. stress point was located near the center of pavement width and stress level(266MPa) is about 66% of yield stress of steel.

• Biomolecules & Therapeutics
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• 제29권4호
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• pp.399-409
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• 2021

1,2-Diacetylbenzene (DAB) is a metabolite of 1,2-diethylbenzene, which is commonly used in the manufacture of plastics and gasoline. We examined the neurotoxic effects of DAB in young and old rats, particularly its effects on hippocampus. Previously, we reported DAB impairs hippocampal neurogenesis but that the underlying mechanism remained unclear. In this study, we evaluate the toxicities exhibited by DAB in the hippocampi of 6-month-old (young) and 20-month-old (old) male SD rats by treating animals intraperitoneally with DAB at 3 mg/kg/day for 1 week. Hippocampal areas were dissected from brains and RNA was extracted and subjected to RNA-seq analysis. RNA results showed animals exhibited age-dependent sensitivity to the neurotoxic effects of DAB. We observed that inflammatory pathways were up-regulated in old rats but that metabolism- and detoxification-related pathways were up-regulated in young rats. This result in old rats, especially upregulation of the TREM1 signaling pathway (an inflammatory response involved in Alzheimer's disease (AD)) was confirmed by RT-PCR. Our study results provide a better understanding of age-dependent responses to DAB and new insight into the association between DAB and AD.