• Textile Coloration and Finishing
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• v.34 no.2
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• pp.102-108
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• 2022

The physicochemical properties of stainless steel fibers which were modified by oxygen plasma treatment were analyzed through microscopy and XPS analysis. The wettability of the surface of the stainless steel fiber was observed by measuring water contact angle to find out the effect of the plasma treatment time on the surface characteristics of the stainless steel fiber. In addition, in order to understand the effect of oxygen plasma treatment on the deterioration of the stainless steel fiber properties, the physical properties due to plasma treatment was investigated by measuring the weight reduction, tensile strength, elongation, tensile modulus of the stainless steel fibers according to the treatment time. As a result, the stainless steel fiber surface was etched by the oxygen plasma and the surface became more wettable by the introduction of hydrophilic functional groups. However the physical properties of the stainless steel fiber were not significantly deteriorated even if the surface of the stainless steel fiber made hydrophilic.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.34 no.1
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• pp.21-29
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• 2023

This paper reviews the global effect of the coronavirus disease 2019 (COVID-19) pandemic on the mental health of children and adolescents in South Korea, the U.S., Japan, and China. We reviewed research on deteriorated mental health, including increased suicide, suicidal thoughts, and self-harm. Various studies have shown that students' mental health issues, such as depression and anxiety, have worsened during the COVID-19 pandemic. Furthermore, the number of students who committed suicide has significantly increased in the U.S. and Japan. Factors such as prior mental health status, change in daily routine, reduced physical activity, excessive screen time, overuse of electronic devices, and reduced social support have been reported to have a significant effect. The chain of deteriorating mental health among the youth began at the onset of COVID-19, social distancing, and school closure. As youths began to stay at home instead of going to school, they lost opportunities to connect with their friends or teachers, who could provide support outside of their homes. Young people spent less time on physical activity and more time online, which damaged their sleeping schedule and daily routine. In preparing for the post-pandemic phase, we should thoroughly analyze the long-term effects of the pandemic on youth mental health, while simultaneously tackling current imminent issues.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.279-287
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• 2018

Sealants are an important element of modern architecture and serve as a building protection against weathering by providing barriers against ingress of moisture, air, and other materials. Exposure to a variety of environments often reduces lifespan due to changes in physical, chemical and mechanical characteristics, and UV, humidity, and temperature expansion are important issues that are directly related to durability. In this study, a combined deterioration test chamber was developed to simulate the environment of the open air as an instrument for verifying the durability of structural sealing materials indoors. In order to replicate special weather conditions, such as yellow dust, acid rain, and contamination by microorganisms, it was deemed impossible to replicate the outdoor environment by 100 %, and the results of the results of the results of the external exposure test of the structural sealant and the combined deterioration testing device. As a result of the displacement test of the outdoor exposure test, it was determined that the sealant was breaking apart and that it would be smooth, and the displacement would be up to three times greater than the initial material value of 1 year. The displacement test results of the combined deterioration test device show the tendency to deteriorate, decreasing the elasticity and tensile characteristics. In the case of denatured silicon, the current 400 cycles have been completed to confirm 12 months of degradation of the external exposure. The deformation of the test specimen cannot be verified with the naked eye, so it is considered that the conditions of the specimen are more stable than the silicon sealant. As a result of the outdoor exposure test, if the combined deterioration test device is structured and proposed in the relevant guidance or specification, the anticipated lifespan of 12 months in the actual use environment can be verified indoors and below 3 months later, economically.

• Journal of the military operations research society of Korea
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• v.29 no.2
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• pp.100-110
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• 2003

Equipment replacement policy may not be defined with certainty, because physical states of any technological system may not be determined with foresight. This paper presents Markov Decision Process(MDP) model for army equipment which is subject to the uncertainty of deterioration and ultimately to failure. The components of the MDP model is defined as follows: ⅰ) state is identified as the age of the equipment, ⅱ) actions are classified as 'keep' and 'replace', ⅲ) cost is defined as the expected cost per unit time associated with 'keep' and 'replace' actions, ⅳ) transition probability is derived from Weibull distribution. Using the MDP model, we can determine the optimal replacement policy for an army equipment replacement problem.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.4
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• pp.112-122
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• 1999

In realistic control systems the nonlinear saturation attributes of the control actuator due to physical limitations should be taken into account This nonlinear saturation of actuators may cause not only deterioration of the control performance but also a large overshoot during start-up and shut-down. As the overshoot increases the system may become oscillatory unstable. in this paper the supervisor implementation which guarantees good performance for saturation operation and prevents reset wind up is presented, Moreover the sufficient conditions of the stability for saturated system using supervisory control with a dynamic controller are provided in the continuous-time and in the discrete-time domain Numerical example is illustrated to depict the efficiency of supervisory control for a typical satuaurated production-distribution system controlled by a discrete-time dynamic controller and to validate basic results by simulation.

• Journal of Applied Reliability
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• v.7 no.4
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• pp.173-181
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• 2007

Out door exposure to daylight and weather climate conditions can cause adverse effect on the properties of automotive plastic materials. The effects of sunlight exposure, especially ultra violet (UV) radiation, can break down the chemical bonds in a polymeric material. This degradation process is called photo-degradation and ultimately leads to color changes, cracking, chalking, the loss of physical properties and deterioration of other properties. To explore the effect of sunlight exposure on the automotive materials, this study investigated photo-oxidation degree and surface property change of molding parts by analytical methods. For the further study, accelerated weathering test methods are proposed, which can correlate with out door weathering, to predict long term performance of automotive plastic materials.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1963-1967
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• 2003

Communication device to use slight movement for serious disabled is proposed. This device is developed mainly for patients suffering from ALS or a cerebral infarction. They often have communication difficulty because of deterioration of muscular functions. Features of this device are that the device is wearable on the user’s body and that it detects the movement of eyebrow. Because of these features, it is quite easy to install the sensor on the patient’s body, not like the conventional sensors. Furthermore, an adaptive communication software is incorporated. A feature of this software is that the arrangement and size of the button and window on the display can be optimized depending on the user's physical ability. In the field test it is confirmed that the communication device developed in this study is successfully helped the people with disability for increasing their communication ability.

• Journal of the Korea Concrete Institute
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• v.16 no.3 s.81
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• pp.433-440
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• 2004

In order to improve the performance of concrete, generally, modern cements often incorporate several mineral admixtures. In this study, the experimental included the flow value, air content of mortar containing limestone powder and length change and compressive strength of mortar specimen immersed in sulfate solutions. From the experimental results, the limestone powder cement matrices improved the physical properties and sulfate resistance of cement matrices at $10\%$ replacement ratio of limestone powder. The $30\%$ replacement ratio of limestone powder was significantly deteriorated in sodium sulfate solution. Irrespective of fineness levels of limestone powder, length change and SDF of mortar specimens with only $10\%$ replacement was much superior to the other replacements.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2011.04a
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• pp.167-171
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• 2011

Managing apartments is critical not only to handling the physical deterioration over time, but also to the quality of community life, social environment and ultimately residents' satisfaction with the housing environment. Therefore, this study aims at understanding residents' awareness of apartment management, and finding the relationship between management activities and residents' satisfaction and participation by comparing an apartment with active management and an apartment without it. This study examines 1) management activities of two subject apartment complexes, and 2) how management activities affect residents' participation and satisfaction. Surveys were conducted of the residents, and SPSS statistics package was utilized to analyze the survey data. This study found that management activities of apartment complex have positive influence on residents' participation and satisfaction with their housing environment. The results of this study can be utilized as basic materials to develop effective guidelines and manual from the perspective of environmental management of apartment houses, in order to improve the participation of the residents in the apartment management.

• CELLMED
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• v.4 no.1
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• pp.1.1-1.13
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• 2014

Epilepsy has now become the most serious brain disorder. A number of synthetic antiepileptic drugs are available in practice, however their effectiveness does not grip true with the entire population suffering from epilepsy. Traditional systems of medicine are popular in developing countries and most of the population relies on traditional medicines for their primary health care need. Medicinal plants to be an important source of traditional medicines. Various plants are used for the treatment of epilepsy in traditional system of medicines and various plants are yet to be scientifically investigated. Phyto-constituents have been the basis of treatment of human diseases including epilepsy. Herbal products are extensively used for the treatment of many diseases worldwide and where allopathic fails or has severe side effects. Psycho neural drugs are also have very serious side effects like physical dependence, tolerance, deterioration of cognitive function and effect on respiratory, digestive and immune system. So the treatments through herbal medicines are widely used across the world due to their wide applicability and therapeutic efficacy with least side effects, which in turn has accelerated the research regarding natural therapy. In this review we have summarized some herbal anti-epileptics.