• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.3
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• pp.207-215
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• 2015

In the last decade, increasing national research fund for recycling the waste FRP (fiber reinforced plastics) ships which has caused environmental problems, improves the technology making concrete-reinforcing fibers out of the waste FRP. Furthermore, the concrete with recycled FRP fiber was tested for the structural performance. Experimental strength tests show that use of recycled FRP powder does not reduce the compressive strength of high strength concrete, and does increase the fire resistance performance of high strength concrete significantly. But, the study in investigating the properties of recycled fiber powder from waste FRP has not been completed because of the absence of the method of separation of mat layer from the waste FRP. This study is to propose a new extracting method of the mat layer from waste FRP, which is the efficient and environment friendly system. and thus it is considered to be the useful recycling method for fire resistance high concrete products or structures.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.6
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• pp.77-84
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• 2007

It is increased electrical energy consumption with the development of intelligence society in hospitals and thus an energy conservation through efficient use of electricity became more important. This paper shows a reasonable design demand factor in hospitals, that was made by the systematic and statistical way considering actual conditions, such as investigated electric equipment capacity, peak power consumption, demand factor, etc., for 32 hospitals and 9 electrical design offices. In this dissertation, it is necessary to analyze the key features and general trend from the investigated data. It made an analysis of the feature parameters, such as average, standard deviation, median, maximum, minimun and thus it was carried the linear and nonlinear regression analysis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.6
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• pp.482-489
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• 2014

This paper suggests the new network scanning algorithm that makes use of measurement pilot of IEEE 802.11k. The purpose of suggesting this algorithm is to improve the existing network scanning schemes. After introducing new algorithm, this paper shows the difference of time property and energy property between former scanning schemes and new scheme with simulation results. Passive scan has a merit of low-power consumption but it takes too long time to fulfill whole scanning. On the contrary, an advantage of active scan is speed but it consumes more battery power than passive scan. By using measurement pilot's smaller interval than beacon interval, the suggested algorithm can consume less power than active scan does, and also make shorter scanning delay than passive scan does.

• Clean Technology
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• v.2 no.2
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• pp.201-213
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• 1996

Environmental regulation has traditionally focused on specific phenomena and adopted the so-called end-of-pipe approach. Recently, however, the new environmental paradigm is more concerned with minimization of waste generation, efficient material and energy use, pollution prevention, etc. The basis of above concept is that one must consider the environmental impacts of a product not only during its manufacturing stage, but during all life stages. In the present study, the current status of LCA and its importance to environmental impacts have been reviewed. In the usual approach to LCA, screening LCA method has been used to promote international competition and define environmental concerns during semiconductor manufacturing. In the present study, a review of semiconductor manufacturing process and its environmental implication has been conducted to quantify the material and energy requirements, minimize the waste generation, and evaluate production cost. Recommended activities are also specified for process modification to improve the process efficiency.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.685-688
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• 2005

An efficient sustain driver and a useful reset circuit composition technique are proposed for plasma display panel drive. The proposed sustain driver uses a series resonance between an external inductor and a panel to recover the energy dissipated by a capacitive displacement current of PDP. It consists of four switching devices, an inductor, and external capacitors, which supply sustain voltage sources. Although the amplitude of an input voltage source is twice as high as that of conventional sustain drivers, average voltage stress imposed on power switching devices is nearly same in their values. Moreover, the input voltage source can be directly applied for the use of a reset voltage source. Owing to this scheme, the proposed sustain driver and the embedded reset circuit have a simple configuration. The operational principle and design example are given with theoretical analyses. The validity of the proposed drive system is verified through experiments using a prototype equipped with a 7.5-inch-diagonal AC plasma display panel.

• Korean Journal of Materials Research
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• v.26 no.2
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• pp.73-78
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• 2016

$TiO_2$ nanoparticles were synthesized by a sol-gel process using titanium tetra isopropoxide as a precursor at room temperature. Ag-doped $TiO_2$ nanoparticles were prepared by photoreduction of $AgNO_3$ on $TiO_2$ under UV light irradiation and calcinated at $400^{\circ}C$. Ag-doped $TiO_2$ nanoparticles were characterized for their structural and morphological properties by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The photocatalytic properties of the $TiO_2$ and Ag-doped $TiO_2$ nanoparticles were evaluated according to the degree of photocatalytic degradation of gaseous benzene under UV and visible light irradiation. To estimate the rate of photolysis under UV (${\lambda}=365nm$) and visible (${\lambda}{\geq}410nm$) light, the residual concentration of benzene was monitored by gas chromatography (GC). Both undoped/doped nanoparticles showed about 80 % of photolysis of benzene under UV light. However, under visible light irradiation Ag-doped $TiO_2$ nanoparticles exhibited a photocatalytic reaction toward the photodegradation of benzene more efficient than that of bare $TiO_2$. The enhanced photocatalytic reaction of Ag-doped $TiO_2$ nanoparticles is attributed to the decrease in the activation energy and to the existence of Ag in the $TiO_2$ host lattice, which increases the absorption capacity in the visible region by acting as an electron trapper and promotes charge separation of the photoinduced electrons ($e^-$) and holes ($h^+$). The use of Ag-doped $TiO_2$ nanoparticles preserved the option of an environmentally benign photocatalytic reaction using visible light; These particles can be applicable to environmental cleaning applications.

• Journal of KIISE:Information Networking
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• v.33 no.6
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• pp.438-450
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• 2006

Geographic routing protocols are very attractive choice for routing in wireless sensor networks because they have been shown to scale better than other alternatives. Under certain ideal conditions, geographic routing works correctly and efficiently. The most commonly used geographic routing protocols include greedy forwarding coupled with face routing. Existing face routing algorithms use planarization techniques that rely on the unit-graph assumption. In real world, many conditions violate the unit-graph assumption of network connectivity, such as location errors, communication voids and radio irregularity, cause failure in planarization and consequently face routing. In this paper, we propose the direction-based geographic routing, which enables energy efficient routing under realistic conditions without planarization techniques. Our proposed approach is for the case in which many sensors need to collect data and send it to a central node. Simulation results show that the protocol exhibits superior performances in terms of energy consumption, delivery success rate, and outperforms the compared protocols.

• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.389-398
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• 2019

Hydrogen energy is not only a solution to climate change problems caused by the use of fossil fuels, but also as an alternative source for the industrial power generation and automotive fuel. Among hydrogen production methods, electrolysis of water is considered to be one of the most efficient and practical methods. Compared to that of the fossil fuel production method, the method of producing hydrogen directly from water has no emission of methane and carbon dioxide, which are regarded as global environmental pollutants. In this paper, the alkaline water electrolysis (AWE) and polymer electrolyte membrane water electrolysis (PEMWE), which are one of the hydrogen production methods, were discussed. Recent research trends of hydrocarbon electrolyte membranes and the crossover phenomenon of electrolyte membranes were also described.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.1
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• pp.24-31
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• 2019

The current study demonstrates an efficient procedure to create ingots from $Al_2O_3$ powder using the skull melting method to use these ingots as a starting material in conventional methods for growing synthetic single-crystal sapphire. Dimension of the cold crucible was 24 cm in inner diameter and 30 cm in inner height, 15 kg of $Al_2O_3$ powder was completely melted within 1 h at an oscillation frequency of 2.75 MHz, maintained in the molten state for 3 h, and finally air-cooled. The areal density and components of the cooled ingot by parts were analyzed through scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS). The areal density and $Al_2O_3$ content of the ingot were related to the temperature distribution inside the cold crucible during high-frequency induction heating, and the area with high temperature was high tends to be high in areal density and purity.

• Journal of Korea Society of Industrial Information Systems
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• v.28 no.1
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• pp.17-25
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• 2023

As the range of use of urban unmanned aerial vehicles (UAV) expands, it is necessary to operate UAVs efficiently because of its limited battery capacity. For this, it is required to find the optimal flight profile with various simulations. Therefore, it is important to predict the power and energy consumption of the UAV battery. In this paper, we analyzed the relationship between the speed and acceleration of the UAV and power consumption during the flight. Then, we derived a linear model, which is easily utilized. In addition, we also derived an accurate power consumption model based on deep neural network learning. To find the efficient model, we used learning data as 1) the GPS 3-axis velocity and acceleration data, 2) the IMU 3-axis velocity only, and 3) the IMU 3-axis velocity and acceleration data. The final model shows 5.86% error rate for power consumption and 1.50% error rate for the cumulative energy consumption.