• Korean Journal of Community Nutrition
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• v.4 no.2
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• pp.254-259
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• 1999

노화는 모든 사람에게 공통적으로 일어나는 자연스러운 현상이다. 그러나 이에 따른 신체적인 변화는 각 개인에 따라, 그리고 한 개인 안에서조차 각종 장기별로 다양한 속도로 진행된다. 노년기의 생리적인 변화는 예비용량(reserve capacity)의 저하에 따라 외부의 스트레스에 대처하여 항상성을 유지하는 능력이 감소되어 나타나게 된다. 안정적 상태에서 기능수준에는 큰 변화가 없으나 활동상태의 기능 수준은 연령증가에 따라 상당히 저하되는 것을 보여준다. 노년기의 생리적 변화에 따라 직병에 대한 감수성은 증가하나 대다수의 만성퇴행성질환은 특정 병리현상에 의해 발생하며 노화가 직접적인 원인으로 작용하지는 않는 것으로 알려지고 있다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.148-153
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• 2017

During natural ageing of HTPB propellant undergoes a series of slow physico-chemical degradation reactions. By using accelerated ageing conditions it is possible to simulate the material behaviour at different time-temperature conditions especially focused on the in-service conditions. Ageing behaviour of HTPB propellant were investigated using HFC(Micro-Heat Flow Calorimeter) is universal technique for measuring the rate of slow chemical and physical processes in long-term storage.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.5
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• pp.59-65
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• 2018

During natural aging, hydroxyl-terminated polybutadiene(HTPB) propellant undergoes a series of slow physico-chemical degradation reactions. By using accelerated ageing conditions it is possible to simulate the material behavior at different time-temperatures focusing on in-service conditions. Aging behaviors of HTPB propellant are investigated using HFC(heat flow calorimeter), a universal technique for measuring the rate of slow chemical and physical processes in long-term storage.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.192-193
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• 2019

본 논문에서는 배터리의 장기적인 노화에 따른 파라미터 분석을 C-rate에 따라서 진행하였다. 이를 위해 배터리 등가회로 모델 기반의 파라미터를 추출하여 분석하였으며 이를 통해 배터리가 노화함에 따라 나타나는 특성을 분석한다.

• Proceedings of the Korean Fiber Society Conference
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• 2002.04a
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• pp.329-332
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• 2002

고밀도 폴리에틸렌(HDPE, High Density Polyethylene) 지오멤브레인은 독성 폐기물 처리시설에서 차수재로 광범위하게 이용되고 있으며, 열이나, 자외선, 그리고 산소와 화학약품에 노출되었을 때의 내구성이 장기성능에 커다란 영향을 미친다 어떤 원인에 의해서 지오멤브레인이 산화될 경우에는 지오멤브레인의 파괴가 가속화되어 구조 시스템의 안정성을 저하시키는 심각한 현상이 발생하게 된다. (중략)

• Membrane Journal
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• v.29 no.4
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• pp.191-201
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• 2019

Before the commercialization of polymeric membranes applicable for industrial application, the homework remains for the high-performance polymers to overcome the practical challenge: long-term stability for prolonged service time. Polymers of intrinsic microporosity (PIMs), exhibiting exceptionally high fractional free volume and high permeability, are susceptible to physical aging where the extra volume created by the inefficient ladder-type packing will lead them from the volumetric equilibrium and reduce the free volume/permeability over time. Here, we will re-examine the physical aging of polymers of intrinsic microporosity, and discuss some of the most prominent attempts to mitigate physical aging in PIMs.

• Korean journal of health promotion
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• v.18 no.4
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• pp.147-158
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• 2018

Background: This study was designed to investigate the effects of usual negative emotional experiences on biological aging progression of human. Methods: A total of 237 subjects who visited the Health Promotion Center at Chungnam National University Hospital from May 2013 through September 2013 was enrolled. Each subject had been drawn up a structured questionnaire about usual experiences of depression, anxiety, anger, and anger expression. The degree of biological aging progression of each subject was computed by a specific formula which consisted of chronological age and biological age reflecting obesity and aging of main organs. Results: Trait anger and low education level showed the significant correlations with biological aging (r=0.160, P=0.014, and r=-0.189, P=0.024, respectively). Trait anger and low education level solely displayed the significant $R^2s$ for biological aging in consequence of multivariate analyses; $R^2=0.044$, P=0.020, and $R^2=0.022$, P=0.038, respectively. Conclusions: This study suggests that the significant relationship between usual anger experience (i.e., trait anger) and biological aging would be present. In addition, lower education level may be related with biological aging.

• Applied Chemistry for Engineering
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• v.35 no.1
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• pp.48-53
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• 2024

We predicted the calendar aging and long-term lifetime of lithium-ion batteries using an electrochemical-based SEI growth model. Numerical simulation was carried out employing the four different long-term SEI growth models (i.e., solvent diffusion limited model, electron migration limited model, Li-interstitial diffusion limited model, reaction limited model), and we calculated the capacity fade and loss of lithium inventory during calendar aging. The result showed that the electron migration limited model and Li-interstitial diffusion limited model showed lower capacity fade, while the solvent diffusion limited model and reaction limited model reached 80% of capacity fade within 10 years. During calendar aging, the lower storage temperature showed less capacity fade due to the hindrance of SEI growth rate. During cycling, the higher C-rate showed a shorter life cycle; however, the differences were not significant.

• International Journal of Highway Engineering
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• v.1 no.2
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• pp.121-133
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• 1999

This study was based on the evaluation of 9 asphalts that were produced in five major Korean refineries. The study was concentrated to identify the problems of the current asphalt specification (KS M 2201) and to determine the ranges of visco-elastic asphalt behavior. As a conventional asphalt property. asphalt penetration, ring and ball(R&B) softening point, asphalt viscosity, and flash point of asphalt were measured. Also Dynamic Shear Rheometer (DSR) were used to evaluate visco-elastic properties of asphalts in the $-20^{\circ}C$ through $30^{\circ}C$ temperature range. These properties before and after the short-term (RTFO) and long-term (PAV) aging were compared and analyzed to achieve the research objectives. The conclusion from this study can be summarized by the followings. The low temperature rheological behavior of all the straight asphalt from five major Korean refineries is similar regardless of asphalt grade. In the mean while, the rheological behavior at high and intermediate temperature of Korean straight asphalt varies depending on asphalt grade.

• Korean Chemical Engineering Research
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• v.48 no.6
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• pp.695-699
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• 2010

The propellant KM10, a single propellant manufactured from nitrocellulose, was known to cause natural degradation phenomena at long term storage. In this study, the self-life was estimated using high temperature acceleration aging tests and stockpile analysis test. For the life expectancy estimation, Arrhenius equation and Berthelot equation were used in the high temperature acceleration tests, and the first order regression was used in the Stockpile analysis test. The self-life of propellant KM10 using the Arrhenius equation and Berthelot equation showed significantly different results as 43.73, 16.53 years in the high temperature acceleration test, and it showed 42.94 years in the Stockpile analysis test. The value of self-life predicted by Arrhenius equation was reasonable when compared with the result of E. R. Bixon.