• Journal of the Korea Institute of Building Construction
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• v.18 no.5
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• pp.419-427
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• 2018

The purpose of this study is to recycle steel slag generated from the iron producing process and to use steel slag as a construction material which is currently landfilled Steel slag is subjected to aging treatment due to the problem of expansion and collapse when it reacts with water. The Slag Atomizing Technology (SAT) method developed to solve these problems of expanding collapse of steel slag. In this study, experimental study on the emergency repair mortar using the reducing slag, electric arc furnace slag and silicon manganese slag manufactured by the SAT method is Reduced slag was shown an accelerated hydration when it was replaced with rapidly-setting cement, and the rate of substitution was equivalent to 15%. It is shown that the electric furnace oxide slag is equivalent to 100% of the natural aggregate, and it can be replaced by 15-30% when the silicon manganic slag is substituted for the electric furnace oxide slag. With the above formulation, it was possible to design the rapidly repair mortar for road use. These recycling slags can contribute on achieving sustainability of construction industry by reducing the use of cement and natural aggregates and by reducing the generation of carbon dioxide and recycling waste slag.

• Journal of KIISE:Computer Systems and Theory
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• v.28 no.5
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• pp.213-217
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• 2001

Excessive memory buffer requirement in continuous media playback is a serious impediment of wide spread usage of on-line multimedia service. Skewed access frequency of available video files provides an opportunity of re-using the date blocks which has been loaded by one session for later usage. We present novel algorithm which minimizes the buffer requirement in multiple sessions of multimedia playbacks. In continuous media playback originated from the disk, a certain amount of memory buffer is required to synchronize asynchronous disk. Read operation and synchronous playback operation. As aggregate playback bandwodth increases, larger amount of buffer needs to be allocated for this synchronization purpose. The focus of this work is to study the asymptotic behavior of the synchronization buffer requirement and to develop an algorithm coping with this excessive buffer requirement under bandwidth congestioon. We argue that in a large scale continuous media server, it may not be necessary to read the blocks for each session directly from the disk. The beauty of our work lies in the fact that it dynamically adapts to disk utilization of the server and finds the optimal way of servicinh the individual sessions while minimizing the overall buffer space requirement. Optimality of the proposed algorithm is shown by proof. The effectiveness and performance of the proposed scheme is examined via simulation.

• Resources Recycling
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• v.17 no.5
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• pp.52-59
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• 2008

Sol-gel process applied in this study was carried out by chelation of metal ions and citric acid. From the results of thermal gravimetric analysis and XRD analysis of gel powder obtained through sol-gel and heat treatment, gel powders are mostly amorphous, and crystallize completely at $900^{\circ}C$, and the crystalline structure of YAG increases with increasing calcinations temperature. Since YAG prepared by sol-gel & calcinations process was porous, and the sape and size was irregular and nonuniform, the shape and size of YAG powder had to be controlled. Therefore the effects of organic materials such as ethylene glycol and surfactant on the crystalline structure of YAG powder were investigated. Polyesterification of ethylene glycol and citric acid separated reaction area of metal ions in the solution and decreased the size of YAG primary particles. The addition of Igepal 630 as surfactant formed the droplet in the solution, and increased the size of primary particles which forms the aggregate of YAG In order to obtain monodispersed YAG particles of uniform size, gel powder prepared with organic materials had to be milled before calcination. And milling process was very important for obtaining YAG of uniform size.

• The KIPS Transactions:PartA
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• v.15A no.1
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• pp.53-60
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• 2008

Streaming media has contributed to a significant amount of today's Internet Traffic. Like traditional web objects, rich media objects can benefit from proxy caching, but caching streaming media is more of challenging than caching simple web objects, because the streaming media have features such as huge size and high bandwidth. And to support various bandwidth requirements for the heterogeneous ubiquitous devices, a transcoding proxy is usually necessary to provide not only adapting multimedia streams to the client by transcoding, but also caching them for later use. The traditional proxy considers only a single version of the objects, whether they are to be cached or not. However the transcoding proxy has to evaluate the aggregate effect from caching multiple versions of the same object to determine an optimal set of cache objects. And recent researches about multimedia caching frequently store initial parts of videos on the proxy to reduce playback latency and archive better performance. Also lots of researches manage the contents with segments for efficient storage management. In this paper, we define the 9-events of transcoding proxy using 4-atomic events. According to these events, the transcoding proxy can define the next actions. Then, we also propose the segment-based caching policy for the transcoding proxy system. The performance results show that the proposing policy have a low delayed start time, high byte-hit ratio and less transcoding data.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.230-236
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• 2019

Recently, issues related to the quality of concrete have continuously resulted in surface quality problems, such as the exfoliation of concrete surfaces due to the cost reduction of cement and poor quality fine aggregate, scaling of surfaces caused by laitance, and plastic shrinkage cracks. Prompted by social issues, the application of a photo catalyst to road structures is being attempted to solve the environmental problems caused by fine dust and automobile exhaust. In this study, chemical admixtures were developed to improve the surface quality of concrete and to apply and distribute titanium dioxide in nanoscale sizes to provide basic data for the development of a photocatalyst-curing agent. As a result of the experiment, silicon and silane were reviewed as a raw material as a curing agent to develop a high performance curing agent with better film performance than conventional curing agents because they could form a film quickly on a fresh concrete surface. The distributed stability of the ultrasonic disperser showed the best performance through an outdoor test for four weeks to review the dispersion measures for the application of nanomaterials.

• Restorative Dentistry and Endodontics
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• v.27 no.1
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• pp.24-33
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• 2002

Leakage studies have been performed frequently, since a fluid-tight seal provided by various dental fill-ing materials has been considered clinically important. The leakage of the various root-end filling materials has been widely investigated mostly dye penetration method. These dye studies cannot offer any information about the quality of the seal of a test material over a long period of time The purpose of this study was to evaluate the microleakage of root end cavities in blood contamination filed amalgam, intermediate restorative material(IRM), light cured glass ionomer cement(GI) and mineral trioxide aggregate(MTA) by means of a modified fluid transport model. Fifty standard human root sections, each 5mm high and with a central pulp lumen of 3mm in diameter, were and filled with our commonly used or potential root end fill ing materials after they were contaminated with blood. At 24h. 72h, 1, 2, 4, 8, and 12 weeks after filling, leakage along these filling materials was determined under a low pressure of 10KPa(0.1atm) using a fluid transport model. The results were as follows : 1 MTA group showed a tendency of decreasing percent of gross leakage (20m1/day) in process of time, whereas the other materials showed a tendency of increasing in the process time. 2. At the all time interval, GI group leaked significantly less than amalgam group and IRM group (p＜0.05). 3. At the 4 weeks, the percentage of gross leakage in MTA group decreased to 0% thereafter, the low per-centage of gross leakage was maintained in MTA group until the end of the experiment, whereas the percentage in IRM group increased to 100% 4. At the 12 weeks, percentage of gross leakage was significantly low in MTA group(0%), comparison with GI group(40%), amalgam group(90%) and IRM group(100%), but there was no significant difference between latter two materials.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.91-98
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• 2009

Recently, production cost of ready mixed concrete has been increased due to the rising cost of raw materials such as cement and aggregate etc. cause by the upturn of oil price and increase of shipping charge. The delivery cost of ready mixed concrete companies, however, has been decreased owing to their excessive competition in sale. Consequently, ready mixed concrete companies began to manufacture the concrete by mixing ground granulated blast furnace slag(GGBF) and fly-ash in order to lower the production cost. Therefore, the objective of this study was to predict 28 days strength of GGBF slag concrete by early strength(warm and hot water curing method) for the sake of managing with ease the quality of ready mixed concrete. In experimental results, the prediction equation for 28 days compressive strength of GGBF slag concrete could be produced through the linear regression analysis of early strength and 28 days strength. In order to acquire the reliability, all mixture were repeated as 3 times and each mixture order was carried out by random sampling. The prediction equation for 28 days strength of GGBF slag concrete by 1 day compressive strength(accelerated testing) according to warm and hot water curing method won the good reliability.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.1
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• pp.101-109
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• 2009

This CW(Construction wastes) are increasing as construction industry is growing, so many countries make efforts to recycle CW. Korea also made a stipulation for recycling CW. But the main content of this stipulation is for using recycled aggregates. Advanced countries try to increase reuse rate of not only recycled aggregate but also other kinds of wastes. So they are adopting SDM(separating dismantlement) method and we are also planning to make the system for SDM. This study is about SDM analysis through construction field investigation and difference analysis between SDM and UDM comparing predictive amount by UDM with real generated amount by SDM. First, the generated amount of construction wastes by SDM is more than estimated amount by UDM, and mixed waste was specially reduced more than UDM. The warehouse is easier than the office building to applicate SDM. But still there is no manual for SDM in the site, so establishment of SDM is demanded.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.7
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• pp.846-851
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• 2005

In this paper, we propose Genetic Algorithms(GAs)-based Optimized Polynomial Neural Networks(PNN). The proposed algorithm is based on Group Method of Data Handling(GMDH) method and its structure is similar to feedforward Neural Networks. But the structure of PNN is not fixed like in conventional neural networks and can be generated in a dynamic manner. As each node of PNN structure, we use several types of high-order polynomial such as linear, quadratic and modified quadratic, and it is connected as various kinds of multi-variable inputs. The conventional PNN depends on the experience of a designer that select the number of input variables, input variable and polynomial type. Therefore it is very difficult to organize optimized network. The proposed algorithm leads to identify and select the number of input variables, input variable and polynomial type by using Genetic Algorithms(GAs). The aggregate performance index with weighting factor is proposed as well. The study is illustrated with tile NOx omission process data of gas turbine power plant for application to nonlinear process. In the sequel the proposed model shows not only superb predictability but also high accuracy in comparison to the existing intelligent models.

• Preventive Nutrition and Food Science
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• v.9 no.1
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• pp.21-28
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• 2004

We purified and characterized a crude polysaccharide from Spirodela polyrhiza with anti-complement activities. The crude polysaccharide fraction (SP-0) which had potential anti-complement activity was extracted in hot water for 4 hrs at 10$0^{\circ}C$. The ethanol-precipitate, the crude polysaccharide traction (SP-1), showed a potent anti-complement activity. Further purification of the crude polysaccharide (SP-1) was carried out by cetavlon, ion exchange chromatography and gel column chromatography. Among cetavlon fractions, SP-4 showed the most potent anti-complement activity. When 100 $\mu\textrm{g}$/mL of SP-4 was incubated with an equal volume of normal human serum (NHS), the TCH$_{50}$ was reduced by about 78%. When the SP-4 fraction was further purified by DEAE-Sepharose (Cl$^{[-10]}$ ), the SP-4IIa, SP-4IIb and SP-4IIc, absorbed fractions, were almost the same as the anti-complement activities of SP-4. SP-4IIc, having the greatest potential activation and the highest yield by ion exchange chromatography, was further purified by gel column chromatography on a Sepharose CL-6B column. Four polysaccharide fractions of SP-4IIc-1, SP-4IIc-2, SP-4IIc-3 and SP-4IIc-4 were obtained, consisting mainly of arabinose, rhamnose, galactose and glucose, with approximate molecular weights of about 305,000, 132,000, 64,000 and 12,000, respectively. Among these subfractions, SP-4IIc-1 had the most potent anti-complement activity. When the SP-4IIc-1 aggregate was applied to a gel column chromatography in 10 mM and 50 mM NaCl solution, the position of the peak fractions shifted to a low molecular weight region, and the molecular weight of SP-4IIc-1 decreased with increased NaCl concentration in the gel column chromatography. It was found that the self-aggregation formed spontaneously in void volume by gel column chromatography using Sepharose CL-6B in water and the self-aggregation significantly affected the anti-complement function.