• Proceedings of the KSR Conference
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• 2009.05a
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• pp.565-573
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• 2009

Even in case of new materials, materials that are not only harmless for the current global environment but also have high-performance and high-function are sought-after in consideration of the global environmental problems. Moreover, in construction areas where a large amount of cement and concrete are used, the establishment of the recycling technology or transformation into resources and energy materials are being put in place. And also, in a situation where the slow and relaxed city and rural life have a high priority, the need for cement and concrete as environmentally friendly new materials that best suit the emotions in human beings is on the rise and a new way to make good use of cement and concrete as new materials in construction technology should be sought. The recently introduced functional and environmentally friendly concrete is aimed at enhancing health through the adjustments of the body biorhythm using far-infrared. Minerals that contain a great amount of the elements with the frequent occurrence of the infrared among earth minerals and concrete are mixed to use structures or finishing materials, which will tackle the issues of smells, mold and corrosion.

• Journal of Environmental Science International
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• v.27 no.2
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• pp.99-107
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• 2018

In order to design the improvement process for T-N removal, the treatment process of Suyoung, Gangbyeon, and Noxan sewage treatment plants (STP) in Busan was anlayzed. Suyoung STP shows a T-N removal efficiency of about 69.8% with MLE(Modified Ludzack ettinger) and A2O+MBR. However, it is necessary to improve the process to maintain over DO of 1 mg/L and is required to install a flow control tank to minimize the rainfall effect. Gangbyun STP shows a about 70.2% T-N removal efficiency with A2O+GFF(gravity fiber filtration). However, in order to improve T-N removal efficiency, it is needed to install MLE process to treat recycle water. Noksan STP shows a T-N removal efficiency of about 71.0% with MLE+Chemical treatment and shows stable T-N concentration in effluent. However, it is required a toxic chemical management process because bad wastewater flows into the STP, also is necessary a process improvement in order to increase internal recycling ratio. Especially, it is required a process improvement to increase HRT of nitrification tank because Suyoung and Gangbyeon STPs shows low nitrification efficiency during winter season.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.11a
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• pp.5-9
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• 2007

The construction method for Foamed-Concrete has not been important due to following process of construction work. However, according to the code about enhance of energy saving design policy and impact noise, noised isolation has been used in construction site so that the resistance for cracking and capability for insulating of Foamed-Concrete has been required. Therefore, new alternatives are demanded. Optimum mixing design, which can get the improvement of insulation and resistance of crack for Foamed-Concrete adding EVA chip, was derived and also the device, applying to construction site, was invented to equalize quality. This device can measure quantity of all input and placement, and show up the sum of placement and mixing design on a touch screen. This valuable construction method is friendly environment and recycling method because of using EVA chip, by-product of an EVA insole scrap burned or embedded, as a light-weight aggregate.

• Smart Structures and Systems
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• v.9 no.2
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• pp.189-206
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• 2012

This paper focuses on the actuation system combined with a piezoelectric transducer and an electric circuit, which leads to a new insight; the electric actuation system is equivalent to mechanical variable-stiffness actuation systems. By controlling the switch in the circuit, the electric status of the piezoelectric transducer is changed, and consequently a variable-stiffness mechanism is achieved on the electric actuator. This proposed actuator features a shift in the equilibrium point of force, while conventional electrically-induced variable-stiffness actuators feature the variation of the stiffness value. We intensively focus on the equilibrium shift in the actuation system, which has been neglected. The stiffness of the variable-stiffness actuator is periodically modulated by controlling the switch, to suppress the vibration of the system in an open-loop way. It is proved that this electric actuator is equivalent to its mechanical counterpart, and that the electrical version has some practical advantages over the mechanical one. Furthermore, another kind of electrically-induced variable-stiffness actuator, using an energy-recycling mechanism is also discussed from the viewpoint of open-loop vibration control. Extensive numerical simulations provide comprehensive assessment on both electrically-induced variable-stiffness actuators employed for open-loop vibration control.

• Hwankyungkyoyuk
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• v.23 no.2
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• pp.129-144
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• 2010

The purpose of this study was to examine the pre-service elementary teachers' perceptions and attitudes toward sustainable development. Subjects were 152 university students, who were surveyed by questionnaire. The instrument consisted of totally 41 items which were constructed by 3 components; 'the perception of concept of sustainable development', 'the attitude toward the relationship between economy and environment' and 'the practical intention of personal change for sustainable lifestyle'. The key findings suggest that most students associate strongly the concepts of sustainable development with their environmental as against economic and social aspect. Most of them incline toward eco-centrism but they had complex attitudes concerning the relationship between economy and environment. They have intention to act for sustainable lifestyle such as purchasing habits, recycling, energy water saving, forms of transportation, nature conservation and education. However, they prefer to act passively than actively in a certain aspect of sustainable lifestyle. Understanding of pre-service elementary teachers' perceptions of and attitudes toward sustainable development will be helpful to work out teaching and learning strategies in environmental education.

• Journal of the Korean Institute of Rural Architecture
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• v.14 no.2
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• pp.35-42
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• 2012

This research intends to find the concept of eco-village in suburban area which various people can experience. For this, we established general ideas through theoretical reflections, and found an objective of suburban eco-village through functional practices. According to the research, a composition of eco-village to reduce the environmental load consists of three major functions. First, by forming traditional meanings of eco-village community, it creates eco-friendly life through energy saving and resource recycling. Second, it functions as relieving the stress of the urbanites and healing their mind and body in the nature of formed eco-village community. Finally, the implementation of eco-village is an idea of group of people who tends to live with nature. Thus, by recovering the nature and by preserving the nature with eco-friendly concept, it will be developed by a place where people can experience the importance of nature. However, these three functions should reflect regional characteristics sufficiently, and through saving and utilizing the history, culture and ecological resources of the regions, it gives positive support to local natives' sustainable life. Consequently, it will show the right direction of development of suburban eco-village through each case analysis of these three functions.

• Environmental Engineering Research
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• v.19 no.3
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• pp.185-195
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• 2014

Despite the enormous technical and economic efforts to improve environmental conditions, currently about 40% of the global population (or 2 billion people) are still lack access to safe water supply and adequate sanitation facilities. Pollution problems and transmission of water- related diseases will continue to proliferate. The rapid population growth and industrialization will lead to a reduction of arable land, thus exacerbating the food shortage problems and threatening environmental sustainability. Natural systems in this context are a transdisciplinary approach which employs the activities of microbes, soil and/or plants in waste stabilisation and resource recovery without the aid of mechanical or energy-intensive equipments. Examples of these natural systems are: waste stabilisation ponds, aquatic weed ponds, constructed wetlands and land treatment processes. Although they require relatively large land areas, the natural systems could achieve a high degree of waste stabilisation and at the same time, yield potentials for waste recycling through the production of algal protein, fish, crops, and plant biomass. Because of the complex interactions occurring in the natural systems, the existing design procedures are based mainly on empirical or field experience approaches. An integrated kinetic model encompassing the activities of both suspended and biofilm bacteria and some important engineering parameters has been developed which could predict the organic matter degradation in the natural systems satisfactorily.

• Journal of Korea Foundry Society
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• v.25 no.6
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• pp.254-258
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• 2005

Semisolid process is possible in any material system possessing a freezing range where the microstructure should consist of the nondendritic globular solid phase separated and enclosed by the liquid phase, referred to as semisolid slurry. There are two primary semisolid processing routes, thixocasting and rheocasting. Especially, rheocasting process has become a new focus in the field of semisolid process because of its many advantages such as no special billet required and possibility of in-house scrap recycling, compared with the thixocasting process. In-Ladle direct thermal control (DTC) rheocasting has been developed, based on the fact that there is slurry and mush transition in every molten metal and the transition, which normally occurs in the range of liquid traction of 0.1 to 0.6, could be controlled by controlling solid shape and relative solid-liquid interfacial energy. In this study, A356 Al alloy was investigated to verify In-Ladle DTC rheocasting for obtaining semisolid slurry. Modeling of heat transfer was carried out to investigate the effect of pouring temperature and ladle material, geometry and temperature and the simulation results were compared with the actual experiments.

• Journal of Microbiology
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• v.43 no.5
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• pp.451-455
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• 2005

In this study, whole cells and a crude enzyme of Candida peltata were applied to an electrochemical bioreactor, in order to induce an increment of the reduction of xylose to xylitol. Neutral red was utilized as an electron mediator in the whole cell reactor, and a graphite-Mn(IV) electrode was used as a catalyst in the enzyme reactor in order to induce the electrochemical reduction of $NAD^+$ to NADH. The efficiency with which xylose was converted to xylitol in the electrochemical bioreactor was five times higher than that in the conventional bioreactor, when whole cells were employed as a biocatalyst. Meanwhile, the xylose to xylitol reduction efficiency in the enzyme reactor using the graphite-Mn (IV) electrode and $NAD^+$ was twice as high as that observed in the conventional bioreactor which utilized NADH as a reducing power. In order to use the graphite-Mn(IV) electrode as a catalyst for the reduction of $NAD^+$ to NADH, a bioelectrocatalyst was engineered, namely, oxidoreductase (e.g. xylose reductase). $NAD^+$ can function in this biotransformation procedure without any electron mediator or a second oxidoreductase for $NAD^+/NADH$ recycling

• Advances in aircraft and spacecraft science
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• v.3 no.1
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• pp.29-43
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• 2016

Composite materials are rapidly gaining popularity as an alternative to metals for structural and load bearing applications in the aerospace, automotive, alternate energy and consumer industries. With the advent of thermoplastic composites and advances in recycling technologies, fully recyclable composites are gaining ground over traditional thermoset composites. Stamp forming as an alternative processing technique for sheet products has proven to be effective in allowing the fast manufacturing rates required for mass production of components. This study investigates the feasibility of using the stamp forming technique for the processing of thermoplastic, recyclable composite materials. The material system used in this study is a self-reinforced polypropylene composite material (Curv$^{(R)}$). The investigation includes a detailed experimental study based on strain measurements using a non-contact optical measurement system in conjunction with stamping equipment to record and measure the formability of the thermoplastic composites in real time. A Design of Experiments (DOE) methodology was adopted to elucidate the effect of process parameters that included blank holder force, pre heat temperature and feed rate on stamp forming. DOE analyses indicate that feed rate had negligible influence on the strain evolution during stamp forming and blank holder force and preheat temperature had significant effect on strain evolution during forming.