• 한국안전학회지
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• 제21권4호
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• pp.13-18
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• 2006

In spite of frequent defect in industrial boilers, life assessment or diagnostic method for them has not been actively studied. In this research, SS400 carbon steel used in industrial boilers is simulated with artificial aging heat treatment. To do qualitative life assessment, differences in micro-structures and hardness of SS400 by the degradation time are studied. In addition, variation in material properties by aging was observed with the tensile test at room temperature and $179^{\circ}C$ and changes in ductile to brittle transition temperature was observed with the charpy impact test performed at several test temperature.

• 비파괴검사학회지
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• 제22권3호
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• pp.284-291
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• 2002

전기비저항법을 이용하여 2.25Cr-1Mo 강의 경년열화도를 평가하고자 하였다. 2.25Cr-1Mo 강이 $540^{\circ}C$에서 장시간 노출되었을 때 일어나는 미세조직 변화를 모사하기 위해 인공 열화를 실시하였으며 열화에 따른 미세조직 인자 (고용원소의 함량), 기계적 성질 (연성-취성 천이온도 ), 전기비저항을 측정하여 이들간의 상호관계를 구하고자 하였다. 열화재에서는 기지내의 고용 원소 (Mo 와 Cr)의 고갈이 나타났다. 연성-취성 천이온도는 열화 초반부에 급격히 증가 후 포화되는 경향을 보인 반면 전기비저항은 열화 초반부에 급격히 감소 후 포화되는 경향을 보였다. 즉, 열화 시간에 따른 연성-취성 천이온도의 변화 경향과 전기비저항의 변화는 서로 반대적으로 변화하는 관계를 나타내었다.

• 한국안전학회지
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• 제17권4호
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• pp.71-79
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• 2002

It was attempted to evaluate the degree of degradation of thermally aged 2.25-1Mo steek by ultrasonic monlinear parameter(UNP) measurement and X-ray diffraction analysis of extracted carbide. Artificial aging was performed to simulate the microstructural degradation in 2.25Cr-1Mo steel arising from long time exposure at $540{\circ}C$. Microstructural analysis (number of carbides per unit area) and measurements of mechanical properties(Vickers hardness, DBTT) and degradation evaluation parameters(UNP and intensity ration of X-ray diffraction peak of electrolytically extracted carbide) were performed. Both of UNP and intensity ratio of X-ray diffraction peak for M6C carbide to that of M23C6 carbide(IR) increased abruptly in the initial 1000 hour of aging and then changed little. UNP and IR were proposed as potential parameters to evaluate the degree of aging degradation of 2.25Cr-1Mo steel.

• 한국전기전자재료학회논문지
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• 제15권8호
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• pp.678-686
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• 2002

This paper presents the effects of accumulation of surface charges on hydrophobic level and the changes of surface potential decay with various artificial environment treatments on high temperature vulcanized (HTV) silicone rubber used for outdoor insulating material. For this study, the charging apparatus by corona discharge, in which grid electrode was installed between the main corona and ground electrode, was used. From this study, it was found that the accumulation of surface charges above a critical surface potential on silicone insulating materials could lead to the temporary loss of surface hydrophobicity. In addition, corona stress and water absorption stress increase the decay rate of surface charges of HTV silicone rubber, while ultraviolet (UV) stress causes longer decay time. We could conclude that the effects of surface charges on hydrophobicity level and the changes of surface state by various artificial treatments were found through a trend of surface potential decay.

• 한국인공지능학회지
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• 제2권1호
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• pp.4-6
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• 2014

These days, aging, the aged and patients rapidly increased to produce problems, for instance, rapid increase of demand on medical service, higher medical expenses, low quality of the elderly's lives, shortage of physicians and nurses, and others [1]. These days, not only IT technology but also medical technology has taken the lead in settlement of the problems. Patients see a doctor to be given medical treatment and service when they are sick to have difficulty. The study investigated lifestyle monitoring system of chronic disease patients to indicate variation depending upon time. The health care is likely to solve problems of the elderly and chronic disease patients and to satisfy desire of better life quality by living healthy life and to diagnose diseases and give medical treatment and to give solutions in accordance with changes of paradigm of medical services.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.9-10
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• 2007

In this paper, we investigated the effect of solar cell breakage on maximum output power of PV module. The test result using artificial light source didn't give any change in output power in case of crack near electrical ribbon. Also, there was a reduction in output power in case of increasing of crack area far from electrical ribbon. But, this experiment is under artificial light source test method. So, when such a PV module is outdoor for a long time, there would be problems on electrical output power and durability because of thermal aging phenomenon of solar cell breakage.

• Computers and Concrete
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• 제10권1호
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• pp.49-57
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• 2012

Nano-particle-reinforced cement mortars have been the basis of research in recent years and a significant growth is expected in the future. Therefore, optimization and quantification of the effect of processing parameters and mixture ingredients on the performance of cement mortars are quite important. In this work, the effects of nano-silica, water/binder ratio, sand/binder ratio and aging (curing) time on the compressive strength of cement mortars were modeled by means of artificial neural network (ANN). The developed model can be conveniently used as a rough estimate at the stage of mix design in order to produce high quality and economical cement mortars.

• Journal of Korean Dental Science
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• 제10권1호
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• pp.29-34
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• 2017

Purpose: The purpose of this study was to evaluate the microleakage of various types of resin-bonded fixed partial dentures (RBFPDs) after artificial aging. Materials and Methods: Forty models with missing first molar were fabricated using artificial resin teeth and were divided into four groups: Group A, conventional RBFPDs design; Group B, modified RBFPDs design; Group C, assembled 3-piece RBFPDs design; and Group D, assembled 3-piece RBFPDs with different occlusal rest positions. Half of the specimens underwent chewing simulation process (240,000 cycles, 50 N load, 1.7 Hz) and thermocycling (temperatures $5^{\circ}C{\sim}55^{\circ}C$, dwelling time 30 seconds) and the remaining 20 specimens didn't receive any treatment. All the specimens were immersed in 2% methylene blue solution for 24 hours to evaluate microleakage, and were sectioned at the middle part of abutment teeth. To evaluate the microleaskage, a dye penetration was calculated. Result: With artificial aging, cyclic loading and thermocycling, a 3-piece RBPFD and a 2-piece RBPFD using original tooth undercuts have significantly lower microleakge (P<0.05) compared to the conventional design of RBPFD and modified RBPFD. Conclusion: Within the limit of this experiment, the assembled RBFPDs exhibited a smaller microleakage than the conventional RBFPDs, implying that the assembled RBFPDs can be more effective for reducing the dislodgement of the RBFPDs.

• 융합정보논문지
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• 제7권6호
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• pp.201-207
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• 2017

수전설비의 고장은 산업과 가정 등 전력을 사용하는 모든 곳에 정전사고를 발생시켜 많은 불편과 문제의 원인이 되고 있다. 수전설비 고장의 주요 원인으로는 노후화를 비롯하여 태풍, 지진을 비롯한 자연재해와 동물 등으로 파악되고 있다. 현재는 수전설비의 온도가 높아지면 고장이 발생한다는 추측만으로 온도의 고온이 지속되는 것을 모니터링한다. 따라서 적기에 수전설비의 고장에 대응하기 어려운 측면이 존재하는 것이 사실이다. 이 논문에서 제안하는 수전설비 모니터링 시스템은 갑작스런 자연재해 등으로 인한 고장을 제외한 일반적인 고장에 대해 효율적으로 대응하는 방안으로 제안한다. 수전설비 모니터링 시스템은 열 감지 센서를 부착하여 수전설비를 실시간으로 감시하고, 감시한 데이터를 수집하여 인공신경망을 이용한 학습을 통해 축적된 정보를 이용하여 고장을 예측한다. 인공신경망의 학습과 실험을 통하여 제안 방식이 효율적임을 보였다.

• 농촌계획
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• 제8권3호
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• pp.41-48
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• 2002

Spatially distributed characteristic of longevity regions analysed using GIS tools. Fundamental factors for long life are categorized into natural conditions and artificial conditions. Degree of longevity is defined and used as a key parameter in analyzing longevity region. It is visually shown that aging areas are moving with time and variances of social and economic status. It is concluded that the degree of longevity is increased with improving living quality because of improvement of economic activities and living environment. However, longevity regions of recent times have slightly reversed tendency against urban areas in the manner of moving toward areas where social and economical activities are relatively weaker.