• Korean Journal of Heritage: History & Science
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• v.47 no.4
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• pp.74-91
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• 2014

The stone statues in the site of Mireuksaji Temple(Iksan, South Korea) were created after the stone pagoda was built in 639. They, transitional statues between animal sculptures and human shaped statues made from the late Goryeo dynasty until the early Joseon dynasty, were set up at the four corners of the stone pagoda by way of guardians. In the case of three statues, their surfaces were denudated and their iconographies have been indiscernible. However, the one in the southwest clearly shows its iconography. It is inferior in properties to the other three statues in the northwest, the northeast and the southeast respectively, but on the other hand its iconography has been well maintained. The reason is related to exposure to harmful environments; specifically, the retaining wall, built around the stone pagoda in the 17th century, had the southwest statue inside and could naturally worked as a buffer against harmful environments. As a result, for about 400 years there has been difference in weathering conditions between the three stone statues and the southwest statue, which brought denudation, the consequent indiscernibleness of iconography and biological invasion to the three statues, notwithstanding superior properties(northwest statue:$176kgf/cm^2$, northeast statue:$109kgf/cm^2$, southeast statue:$273kgf/cm^2$). In contrast, the southwest statue significantly shows its iconography with black contaminants and granule decomposition, despite inferior properties($133kgf/cm^2$). Defenseless exposure to external environment is not recommended for the stone statues, because it is hard to preserve the extant iconography. Herein lies the application of the data on microclimate around Mireuksaji Temple. As regards the weathering zone in which the stone statues are located, Conservation increases in acidity and frequency as years go by, Hereat, in the approach to the Conservation of stone statues, the first consideration needs to be morphological historicity rather than geographical location.

• Korean Journal of Heritage: History & Science
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• v.51 no.1
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• pp.32-47
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• 2018

The purpose of this study is to examine the vegetation maintenance project that was conducted as a part of the Official Development Assistance (ODA) project for the historic site of Angkor, to analyze the aspects and characteristics of the project, and to derive implications for the establishment of future policies and strategies. First, the key words used in the vegetation maintenance project at the historic site of Angkor do not only refer to the concept of plants (and more specifically to 'trees') but also to the concept of heritage. In other words, the concept of heritage is not limited to architectural structures but is also intended to mean the vegetation and surroundings that form the historic site. Second, the expansion of the value of vegetation has contributed to the establishment of the basic principles of conservation based on the 'coexistence' between architectural structures and vegetation; here, vegetation has come to be recognized as an 'essential' element in the conservation of historic sites. Third, the range of vegetation maintenance has expanded from each tree to the surroundings of the temples, and vegetation maintenance came to adopt 'integrative' and 'active' directions to improve not only the growth environment of the vegetation but also the viewing environment experienced by visitors. This change means that it is necessary for the historic site maintenance project to comprehensively deal with the temples and their surrounding areas. Fourth, for the effective performance of the ODA project, the role of the International Coordinating Committee for the Safeguarding and Development of the Historic Site of Angkor (ICC-Angkor), under the influence of UNESCO, was expanded from an examination of the problems with the existing projects to a search for solutions to technical consultation and supervision. This implies that, in order to perform the ODA project in a way that is appropriate to the local conditions, it is important to reach gradual and phased agreements with ICC-Angkor.

• Journal of the Korean Geotechnical Society
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• v.26 no.7
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• pp.117-133
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• 2010

A hybrid system of soil-nailing and compression anchor is proposed in this paper; the system is composed of an anchor bar (installed at the tip) with two PC strands and a steel bar. After drilling a hole, installing proposed hybrid systems, and filling the hole with grouting material, prestress is applied to the anchor bar to restrict the deformation at the head and/or to prevent shallow slope failures. However, since the elongation rate of PC strand is much larger than that of steel bar, yield at the steel bar will occur much earlier than at the PC strand. It means that the yield load of the hybrid system will be overestimated if we simply add yield loads of the two - anchor bar and PC strands. It might be needed to try to match the yielding time of the two materials by applying the prestress to the anchor bar. It means that the main purpose of applying prestress to the anchor bar should be two-fold: to restrict the deformation at the nail head; and more importantly, to maximize the design load of the hybrid system by utilizing load transfer mechanism that transfers the prestress applied at the tip to the head through anchor bar. In order to study the load transfer mechanism in a systematic way, in-situ pullout tests were performed with the following conditions: soil-nailing only; hybrid system with the variation of prestress stresses from 0 kN to 196 kN. It was found that the prestress applied to the anchor system will induce the compressive stress to the steel bar; it will result in decrease in the slope of load-displacement curve of the steel bar. Then, the elongation at which the steel bar will reach yield stress might become similar to that of PC strands. By taking advantage of prestress to match elongations at yield, the pullout design load of the hybrid system can be increased up to twice that of the soil-nailing system.

• Journal of the Korean Association of Geographic Information Studies
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• v.18 no.4
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• pp.14-30
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• 2015

This paper attempted to analyze the hydraulic effects that the dredging can take as an alternative to reduce possible damages of flooding due to the overflow of river levee in meandering rivers, where riverbed aggradation, seepage and erosion may occur. In order to make a hydraulic analysis in a section of meandering rivers, a two-dimensional hydraulic analysis model, RMA-2, was selected. The GIS was applied to construct two-dimensional finite element grids to consider the hydraulic conditions before and after dredging. The water surface elevations, depths, velocities, and tractive forces were compared before and after the dredging. The difference of water surface elevation between the inside and outside of river was turned out to be the maximum value of 0.58m under the design flood condition. It could be evaluated that the tractive force at the bank decreased about 42 to 67% on average for all the sections. These results could give valuable information that the dredging of the stream channel at the meandering sections decreased the risk of overflow, seepage and erosion of the banks. The methodologies given in this study will contribute to mitigating the flood damages in the surrounding farmlands.

• Physical Therapy Rehabilitation Science
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• v.5 no.4
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• pp.210-214
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• 2016

Objective: The aim of this study was to measure the muscle architectural parameters of abdominal muscles in healthy individuals by rehabilitative ultrasound imaging (RUSI) and to investigate their changes after bridging exercise in various environments. Design: Cross-sectional study. Methods: The study included 40 healthy participants (19 men, 21 women). Subjects were randomly allocated to a stable surface group (SG, n=20) or an unstable surface group (UG, n=20). The participants assumed three positions in rest, bridging exercise with knee flexion $60^{\circ}$, and bridging exercise with knee flexion $90^{\circ}$ for the measurement of abdominal muscle thickness by RUSI. For the resting position, the participants held the head neutral in a hook-lying position and the dominant side was measured. For contraction, the participants performed the bridging exercise with the knee joint in $60^{\circ}$ and $90^{\circ}$ of flexion for 10 seconds each. Results: For transversus abdominis, external oblique muscle thickness, within the stable surface group and the unstable surface group, no significant contraction difference was observed in both the $60^{\circ}$ and $90^{\circ}$ bridge exercise conditions. Contraction difference of internal oblique muscle was significantly larger at $90^{\circ}$ than at $60^{\circ}$ within the SG (p<0.05). But within the UG, no significant contraction difference was shown. There was no significant contraction difference between the surface group and the unstable SG at $60^{\circ}$ condition and at $90^{\circ}$ condition in all measured muscles. Conclusions: The contraction difference is different for each muscle during bridge exercise with knee flexion $60^{\circ}$ and bridging exercise with knee flexion $90^{\circ}$. Muscle contraction difference is generally large when exercised on an unstable surface than a stable surface, but these are not statistically significant when bridging exercise is performed using dynamic air cushion for unstable surface.

• Korean Journal of Construction Engineering and Management
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• v.18 no.2
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• pp.30-37
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• 2017

In Korea, additional indirect costs generated from the time period extension of public construction projects have been studied. Practical claims against such costs are increasing. There are no clear criteria for calculating the delay cost caused by the extension, and thus calculation methods differ across entities. Logical valid calculation methods have also not been researched. Further, there are no Korean studies on the additional indirect cost caused by a suspension in a public construction project on a long-term continuing contract. The purpose of this research is to propose a method of calculating the indirect cost incurred by construction time extension that reflects the characteristics of Korean public construction projects. The cost patterns generated during construction periods were analyzed, and then the current criteria of calculating the indirect costs caused by the extension were examined. Following this, actual conditions and practices in the field were surveyed and the current calculation method was applied to a model case to compare the actual cost and that determined from the current calculation method. Issues with the current method were identified by this comparison. Based on this, this research proposes a method of calculating the total actual cost caused by a suspension in a public construction project that is appropriate for calculating the additional indirect cost generated by a suspension in a public construction project on a long-term continuing contract.

• Journal of Wetlands Research
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• v.17 no.1
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• pp.11-18
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• 2015

As the seriousness of water pollution resulted from nitrogen is being magnified, research has been conducted to reduce nitrogen in sewage as well as wastewater. Particularly research on innovative nitrogen removal methods that are based on the reaction of nitritation and are economically feasible and eco-friendly has been receiving attention. However, research on the applicability and efficiency of the methods based on the reaction of nitritation has not been completely done yet. Accordingly, the current study has analyzed the characteristics of sewage flowing into municipal wastewater treatment plants, primary clarifier supernatant, recycled water, and livestock wastewater and also operated a laboratory-level reactor. The result shows that recycled water and livestock wastewater contain higher-concentration nitrogen than other kinds of sewage, so they increase nitrogen loading in the water treatment line. And the result of operating a reactor shows that because of ammonium nitrogen low concentration, sewage and primary clarifier supernatant do not induce the reaction of nitritation. Also, there exist differences in the conditions of retention time inducing the reaction of nitritation by the types of sewage, and this seems to be attributed to organic compound and ammonium nitrogen concentration. Among the kinds of sewage inducing the reaction of nitritation, anaerobic digester supernatant indicates the highest efficiency.

• Smart Media Journal
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• v.6 no.4
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• pp.58-64
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• 2017

Modern society is characterized by rapid increase in world population, aging of the rural population, decrease of cultivation area due to industrialization. The food problem is becoming an important issue with the farmers and becomes rural. Recently, the researches about the field of the smart farm are actively carried out to increase the profit of the rural area. The existing smart farm researches mainly monitor the cultivation environment of the crops in the greenhouse, another way like in the case of poor quality t is being studied that the system to control cultivation environmental factors is automatically activated to keep the cultivation environment of crops in optimum conditions. The researches focus on the crops cultivated indoors, and there are not many studies applied to the cultivation environment of crops grown outside. In this paper, we propose a method to improve the harvestability of poor areas by monitoring the areas with bad harvests by using big data analysis, by precisely predicting the harvest timing of fruit trees growing in orchards. Factors besides for harvesting include fruit color information and fruit weight information We suggest that a harvest correlation factor data collected in real time. It is analyzed using the Apache Spark engine. The Apache Spark engine has excellent performance in real-time data analysis as well as high capacity batch data analysis. User device receiving service supports PC user and smartphone users. A sensing data receiving device purpose Arduino, because it requires only simple processing to receive a sensed data and transmit it to the server. It regulates a harvest time of fruit which produces a good quality fruit, it is needful to determine a poor harvest area or concentrate a bad area. In this paper, we also present an architectural model to determine the bad areas of fruit harvest using strong data analysis.

• Journal of the Korea Concrete Institute
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• v.15 no.1
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• pp.117-124
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• 2003

Reinforced concrete structures under sever conditions such as marine structures, bridges and structures constructed with aggregates(dredged from sea), can be deteriorated from corrosion of the reinforcing bars. The purpose of this study is to evaluate the anti-corrosive performance of coated steel using polymer cement slurry. Polymer cement slurry with various polymer dispersions and corrosion inhibiting agent were coated to the surface of bars, and tested for accelerated corrosion tests. Tests include immersion in NaCl 10% solution, chloride ion spray, autoclave cure, autoclave cure after carbonation, penetration of NaCl 10 % solution, carbonation after penetration of NaCl 10% solution. Test results, show that the anti-corrosive performace is considerably improved by using polymer cement slurry at surface of steel. And this trend is marked by adding of corrosion inhibiting agent. This difference of the anti-corrosive properties is hardly recognized according to types of polymer dispersions. The coated steel using polymer cement slurry will be improved to a great extent compared to those of plain steel when increasing content of chloride ion in cement concrete.

• Journal of the Korea Concrete Institute
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• v.19 no.6
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• pp.785-793
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• 2007

An electrochemical transient response technique was used to study the corrosion of reinforcing steel bar in the concrete. Analysis of the transient electrochemical potential response in a corrosion interface to an applied current has enabled the separate components that make up the measured transient response to be isolated. These components display a range of resistances and capacitances, dependent on the corrosion conditions of the reinforcing steel, which may be attributed to the corrosion process, to effects within the concrete cover or to film effects on the surface of the concrete. In this technique, the corrosion rate was evaluated by summing all of the resistances in the separate components to obtain an aggregated corrosion resistance. However, it is possible that not all resistances identified are associated with the corrosion process. The results obtained show that the corrosion rates are significant dependent on the assignment of the separate components to either corrosion or to other processes. The assignment of resistive components associated with the corrosion rate can be clearly identified by taking a series of the transient measurement at different lateral distances from the corroding reinforcing steel. An inappropriate selection of measurement time however may result in an additional resistance, which is not associated with corrosion, being included or part of the resistance associated with corrosion being left out.