• 드라이브 ㆍ 컨트롤
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• 제12권4호
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• pp.28-34
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• 2015

Because heavy-duty construction vehicles such as excavators are required for good engine-room cooling capacity, a hydraulic gear motor is adopted in the cooling fan drive mechanism to actively control the output speed, instead of adopting the conventional ON/OFF type belt drive. While gear motors are normally limited to 140bars of operating pressure, those for the cooling fan are capable of operating at continuous pressures of up to 220bars. After assembly, all gear motors for high pressure must pass an aging test which is a kind of the wearing process between the gear teeth and motor housing. During the aging process with gradual pressure increments, gear sticking sometimes occurs due to abnormal wear, resulting in defects. This paper focuses on a gear-sticking free aging test controller that is designed together with the knowledge of an experienced operator and the analysis results of experimental data of the gear jamming phenomenon. From the aging experiment, it is demonstrated that the developed controller that can alter the setting pressure of the load pump is effective for stabilizing the abrupt increase in the motor input pressure, thus preventing the hydraulic motor from stopping. This is expected to be helpful for the reduction of defects and increase in productivity.

• 약학회지
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• 제19권4호
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• pp.219-226
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• 1975

Physical and chemical properties on the aging inhibition mechanism of hydrous aluminum oxide were studied by means of dehydration velocity, activation energy, DTA, TGA, IR spectra, X-ray diffraction and TMA. During aging, changes may occur in the hydrous aluminum oxide structure which results in a loss of acid reactivity and in crystal formation to the hydrated hydrous alumina. The results obtained from the X-ray diffraction pattern and DTA, TGA thermogram studies showed that the aging product stabilized with either sorbitol or mannitol was hydrous aluminum oxide ($Al_{2}O_{3}{\cdot}xH_{2}O$) but the aging product not stabilized with either sorbitol or mannitol product not stabilized was hydrated hydrous aluminum oxide $Al_{2}O_{3}{\cdot}xH_{2}O{\cdot}yH_{2}O$. The activation energy of dehydration of the hydrous almina was about 17 Kcal. mol$^{1}$ deg$^{-1}$ which was observed a little less than that of 22 kcal.mol.$^{-1}$ deg.$^{-1}$ of or mannitol, the inhibition mechanism in the aging process from oxide is assumed to prevent the formation of the hydrated hydrous aluminum oxide and the aging process is thought of as analogous to the polymorphic transformations which occur as a system converts to its most stable state.

• 한국기계가공학회지
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• 제21권1호
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• pp.56-65
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• 2022

The electrochemical corrosion properties of austenitic AISI 304 steel subjected to a long-term-aging heat treatment were investigated. AISI 304 steel was aged at 700 ℃ for up to 10,000 h. The variation in the microstructure of the aged specimens was observed by optical microscopy and scanning electron microscopy. Electrochemical polarization experiments were performed to obtain the corrosion current density (Icorr) and corrosion potential (Ecorr). Analyses indicated that the metastable intermetallic carbide M₂₃C₆ formed near the γ/γ grain boundary and coarsened with increasing aging time; meanwhile, the δ-ferrite decomposed into the σ phase and into M₂₃C₆ carbide. As the aging time increased, the current density increased, but the corrosion potential of the austenitic specimen remained high (at least 0.04 ㎛/cm²). Because intergranular carbide was absent, the austenitic annealed specimen exhibited the highest pitting resistance. Consequently, the corrosion resistance of austenitic AISI 304 steel decreased as the aging heat treatment time increased.

• Nuclear Engineering and Technology
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• 제56권4호
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• pp.1472-1479
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• 2024

Cyber-Physical Energy Systems (CPESs) integrate cyber and hardware components to ensure a reliable and safe physical power production and supply. Renewable Energy Sources (RESs) add uncertainty to energy demand that can be dealt with flexible operation (e.g., load-following) of CPES; at the same time, scenarios that could result in severe consequences due to both component stochastic failures and aging of the cyber system of CPES (commonly overlooked) must be accounted for Operation & Maintenance (O&M) planning. In this paper, we make use of Deep Reinforcement Learning (DRL) to search for the optimal O&M strategy that, not only considers the actual system hardware components health conditions and their Remaining Useful Life (RUL), but also the possible accident scenarios caused by the failures and the aging of the hardware and the cyber components, respectively. The novelty of the work lies in embedding the cyber aging model into the CPES model of production planning and failure process; this model is used to help the RL agent, trained with Proximal Policy Optimization (PPO) and Imitation Learning (IL), finding the proper rejuvenation timing for the cyber system accounting for the uncertainty of the cyber system aging process. An application is provided, with regards to the Advanced Lead-cooled Fast Reactor European Demonstrator (ALFRED).

• 한국생명과학회:학술대회논문집
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• 한국생명과학회 2000년도 제28회 학술심포지엄
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• pp.9-10
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• 2000

The aging process is multifactorial and results from the combined effects of inherited(genetic) and acquired factors including life style, food habits, physical activity, and diseases. That give rise to the various approaches in aging. We are trying to study biological changes with aging, In detail we are focused on gene and protein function accompanied by normal or abnormal aging process, especially our efforts are aimed at revealing the functional relationship of proteins in aging as a final product of gene. We expect that proteomic approach to the study of protein function involved in aging should give us variety of integrated data to understand biological changes of long lived lives, We have applied expression proteomics to rat liver bred in dietary restriction or in at libitum to elucidate the effects of food habit on aging. Expression proteomics shows us protein profile in a selected tissue or cells as a whole and gives us the information about protein expression level, posttranslational modification and degenerative modification of expressed proteins. Comparative analysis of young and old rat liver by two dimensional gels shows that gene expression of several proteins was down regulated in old rats and some protein expression level is increased with aging. Dietary restriction slows down these changes of gene expression and in some proteins there's no difference in protein expression level at same ages in comparison with rats bred in at libitum. About forty protein was identified by peptide mass fingerprint with MALDI-TOF and rest of the protein of interest is in the course of identification, Also we are trying to make mitochondrial and cytosolic proteom reference map. These suborganelle proteom map will gives us the information about low abundance proteins and cellular localization of proteins. Proteomics is a growing methodology to study biological system. High throughput qualitative and qualitative aspect of this approach will gives us large amount of integrated information and speed up our understanding about biological system

• 대한토목학회논문집
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• 제32권2A호
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• pp.109-116
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• 2012

지진격리장치로서 납고무받침의 동적 특성은 주재료인 고무재료의 동적거동과 비선형 성질에 의존하고 있다. 역학적이나 환경적인 영향으로 인해 고무재료에 노화가 진행되고 결국에는 손상이 불가피하게 발생하게 된다. 고무재료의 노화의 주원인은 높은 온도에서 반응열로 인한 산화반응으로 알려져다. 이에 따라 납고무받침의 가속 열 노화실험을 수행하여 열 노화 전 후에 대해 받침의 특성값을 상호 비교하였다. 실험 결과 열 노화 현상은 전단강성과 에너지 감쇠 그리고 등가감소계수에 영향이 있음을 알 수 있었다. 또한 열 노화에 의한 동적특성의 저하를 실제 교량에 적용하여 납고무받침의 열 노화가 교량의 교각의 내진성능에 미치는 영향을 수치해석을 통해 비교분석하였다. 해석결과 납고무받침에 대하여 열 노화에 따른 기본 특성변화가 교량의 내진성능에 미치는 영향은 크지 않음을 알 수 있었다.

• 약학회지
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• 제35권4호
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• pp.277-282
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• 1991

Rheological, colloidal and micromeritical properties were followed to investigate aging mechanisms of hydrous aluminum oxide suspension using Zeta-meter systems, BET adsorption apparatus, Master sizer and electronmicroscope. The results indicate that hydrous aluminum oxide suspension revealed plastic flow with thixotropy. The viscosity, thixotropy and yield value were increased with increasing concentration. During aging process, the viscosity and thixotropic index were increased by an addition of glycerin, however, sorbitol stabilized aging process of the suspension being accompanied with growth of particle size and reduction in specific surface area, pore area and pore volume, and consistency. Diminution of adsorptive power of the particles was also protected by addition of sorbitol to hydrous aluminum oxide suspension. From these results, one of aging mechanism of hydrous aluminum oxide suspension assumed growth and/or crystallization of colloidal particles in aqueous suspension.

• KIEE International Transactions on Power Engineering
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• 제5A권1호
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• pp.40-45
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• 2005

Substation facilities have become extremely large and complex parts of electric power systems. The development of condition monitoring and diagnosis techniques has been a very significant factor in the improvement of substation transformer security. This paper presents a method to analyze the cause, the degree, and the aging process power transformers by the Self Organizing Map (SOM) method. Dissolved gas data were non-linearly transformed by the sigmoid function in SOM that works much the same way as the human decision making process. The potential for failure and the degree of aging of normal transformers are identified by using the proposed quantitative criterion. Furthermore, transformer aging is monitored by the proposed criterion for a set of transformers. To demonstrate the validity of the proposed method, a case study is performed and its results are presented.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.143.1-143.1
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• 2003

Peroxynitrite and 4-hydroxynonenal (4-HNE) are highly reactive molecules which are generated under oxidative stress condition and during aging. Many proteins in living organism are modified by them and consequently associated with various diseases including cardiovascular and neurodegenerative diseases. We hypothesize that peroxynitrite and 4-HNE modified serum proteins are also associated with aging process. To establish information on peroxynitrite and 4-HNE adducted proteins for aging study, we used proteins methods, 2D-PAGE and MALD-TOF MS, to identify modified proteins from young (70month) and old (25-month) rat serum. (omitted)

• 한국융합학회논문지
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• 제8권10호
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• pp.351-358
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• 2017

본 연구는 영화 '수상한 그녀'에서 노령화에 대한 애도의 과정을 융 복합적으로 분석하였다. 영화의 내용을 반복적으로 탐색하면서 주인공이 노화과정에서 나타난 노년의 상실감을 애도의 과정으로 해석하면서 정신분석학적으로 탐색하였다. 즉 노화 과정을 인생의 재해석 과정과 향후 삶에 대한 발달적 태도 변화를 애도의 심리세계로 정신분석학적으로 분석하였다. 연구결과의 애도과정은 '상실과 결핍' ${\rightarrow}$ '도피와 퇴행' ${\rightarrow}$ '탈동일시와 탈집중' ${\rightarrow}$ '새로운 현실 적응'으로 나타났다. 이와 같은 결과에 의하여 상담자는 내담자의 애도작업이 원만하게 이루어지도록 심리적 애도환경 조성에 주력해야 할 뿐 아니라, 내담자의 애도능력 향상을 위한 복합적 상담기법을 구사할 수 있어야 함을 제언하였다.