• Journal of the Korean Chemical Society
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• v.54 no.6
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• pp.749-754
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• 2010

In this study, rubber vulcanization property, change in physical property, morphology and chemical characteristics of blended rubber depending on various IR/CR ratio were investigated for the purpose of the improvement of material property and durability. The effect of surface treatment by chlorine on the friction coefficient was also studied with various conditions of surface treatment. In terms of vulcanization property, as the amount of CR content increased, the speed of cure was decreased, while the density of crosslinking stayed constant. It means hardness and modulus were increased as the CR content increased. It is related to change in cure property and mechanical strength was improved by the effect of crystallization reaction. In the aging property, as the CR content increases, the changed amount of basic properties were decreased, which acts as a reducing factor in change of aged property by complementing weak point in mechanical property. It was found that the degree of property change for surface treated samples were reduced. According to the microscopic result, the degree of surface dispersion on rubber blends was increased by increasing CR content. Rubber surface showed uniform direction in pattern with increased smoothness and luster by treatment with chlorine. The degree of rubber reforming was measured by the remaining amount of chlorine and the friction coefficient was dependent on the amount of chlorine combined with rubber. In the initial stage of surface treatment, from 10 to 40 phr, the friction coefficient of specimen was rapidly reduced. However, as the concentration of chlorine solution increased, the change in friction coefficient was decreased.

• Journal of Soil and Groundwater Environment
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• v.14 no.6
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• pp.1-18
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• 2009

A series of three-dimensional numerical simulations using a generalized multidimensional hydrodynamic dispersion numerical model is performed to simulate effectively and to evaluate quantitatively impacts of urbanization on density-dependent groundwater flow and salt transport in a coastal aquifer system, Suyeong-Gu, Busan, Korea. A series of steady-state numerical simulations of groundwater flow and salt transport before urbanization with material properties of geologic formations, which are established by numerical modeling calibrations considering all the urbanization factors, is performed first without considering all the urbanization factors. A series of transient-state numerical simulations of groundwater flow and salt transport after urbanization is then performed considering the urbanization factors individually and all together. Finally, the results of both numerical simulations are compared with each other and analyzed. The results of the numerical simulations show that density-dependent groundwater flow, salt transport, and seawater intrusion in the coastal aquifer system are intensively and extensively impacted by the urbanization factors. Especially, these urbanization factors result in the changes of the total groundwater volume and salt mass in the coastal aquifer system. However, such impacts of each urbanization factor are not spatially uniform but locally different.

• Journal of Soil and Groundwater Environment
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• v.12 no.5
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• pp.33-36
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• 2007

In recent years the convective-dispersive equation has been often discredited in predicting subsurface solute transport under field conditions due to presence of preferential flow paths. Kim et al. (2005) proposed a simple equation that can predict the breakthrough of solutes without excessive data requirements. In their Generalized Preferential Flow Model (GPFM), the soil is conceptually divided in a saturated "distribution layer" near the surface and a "conveyance zone" with preferential flow paths below. In this study, we test the model with previously published data, and compare it with a classical convective-dispersive model (CDM). With three parameters required-apparent water content of the distribution zone, and solute velocity and dispersion in the conveyance zone-GPFM was able to describe the breakthrough of solutes both through silty and sandy loam soils. Although both GPFM and CDM fitted the data well in visual, variables for GPFM were more realistic. The most sensitive parameter was the apparent water content, indicating that it is the determining factor to apply GPFM to various soil types, while Kim et al. (2005) reported that changing the velocity of GPFM reproduced solute transport when same soils were used. Overall, it seems that the GPFM has a great potential to predict solute leaching under field conditions with a wide range of generality.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.9
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• pp.826-834
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• 2004

In this paper, we fabricated thick film monopole antennas using Bi$_2$O$_3$-doped BaTi$_4$$O_{9}$ ceramics for small size and broadband intenna. In the result, the high permittivity was fixed and the quality factor was also significantly decreased by the formation of secondary phase of Bi$_4$Ti$_3$O$_{12}$ repleced by addtion Bi. The antenna property influenced by the quality value more than the permittivity. The bandwidth of antenna was increased to 33 %. On the other hand, the gain was reduced to -4.3 dBi. Also radiation patterns were showed low dBi value by increasing of dielectric loss. Specially, Measured x-y plane radiation patterns was distorted as the dispersion of wavelength and high permittivity difference. But the result is showed execellent bandwidth because of low quality value in all formation range.nge.

• Journal of the Korean Electrochemical Society
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• v.12 no.2
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• pp.181-188
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• 2009

Pt catalyst was adsorbed on Carbon nanofiber (CNF) by modified polyol method after acid treatment of the carbon support with $HNO_3$ and $H_{2}SO_{4}$. As the time for acid treatment increases, more oxygen functional groups on carbon surface were produced which improve the loading amount and dispersion of Pt catalyst on carbon supports. In order to inspect the effect of CNF acid treatment time on electrochemical corrosion, constant potential of 1.4 V was applied to a single cell for 30 min and the amount of $CO_2$ emitted was monitored with on-line mass spectrometry. According to the results of our experiment, more $CO_2$ was produced with Pt/ oxidized-CNF catalyst in compared to that with unoxidized-CNF. Increasing acid treatment time also induces the more $CO_2$ emission. Besides, performance degradation after corrosion test expanded with severer carbon corrosion. From the observed results, it can be concluded that the acid treatment of CNF is beneficial to catalyst loading, but it also is a significant factor declining the fuel cell durability by accelerating electrochemical oxidation of carbon support.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.12
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• pp.689-695
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• 2015

A biofilm filtration for the removal of gaseous pollutants has been recognized as a process with a complex interaction between the gas flow characteristics and the process operating variables. This study aims to develop an one dimensional dynamic numerical model which can be utilized as a tool for the analysis of biofilm filtration process operated in plug flow mode. Since, in a plug flow system, minor environmental changes in a gaseous unit process cause a drastic change in reaction and the interaction between the pollutants is an influencing factor, plug flow system was generalized in developing the model. For facilitation of the model development, dispersion was simplified based on the principles of material balance. Several reactions such as competition, escalation, and control between the pollutants were included in the model. The applicability of the developed model was evaluated by taking the calibration and verification steps on the experimental data performed for the removal of BTX at both low and high flow concentration. The model demonstrated a correlation coefficient ($R^2$) greater than 0.79 under all the experimental conditions except for the case of toluene at high flow condition, which suggested that this model could be used for the generalized gaseous biofilm plug flow filtration system. In addition, this model could be a useful tool in analyzing the design parameters and evaluating process efficiency of the experiments with substantial amount of complexity and diversity.

• Journal of Information Management
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• v.37 no.2
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• pp.1-20
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• 2006

It has lately been recognized that the sharing and exchanging of the research results information is the critical factor to improve the research productivity. So many institutions are planning or developing the information systems which provide the research information services for researcher. But it has very difficulty in integrating the research resources information due to the dispersion and heterogeneity in data sources, and semantic and structural difference in describing data. We propose the semantic web based methodology and conceptual framework for raising the interoperability of metadata about research results information, which will support the integration of the distributed research data for information services in the end. We first introduce the ontology which is developed based on Standard Metadata of Research Results Information published by STISC. Then to show the applicability in real-world environment, we express the metadata of research information in RDF/RDFS according to ontology. Finally we proposed the conceptual architecture of research information service system which shows the main components, the functional requirements, and the principal and design direction at implementing the system.

• Ecology and Resilient Infrastructure
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• v.6 no.4
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• pp.191-199
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• 2019

Road development is considered an important factor in invasion and dispersion of ailen plants by damaging the natural ecosystems and connecting the detached landscapes into long tubular structures. In this study, vegetation survey was carried out according to the topographical characteristics of cut slope, fill slope, and flat land at the construction site in order to understand the effect of road developemt on the change of the floristic composition of ailen plants. Road developement projects caused a lot of changes in annual and biennial alien plants because of continuous disturbances. Changes in species composition of alien plants decreased in the cut slope. On the other hand, the ailen palnts of the fill slope increased. The increase or decrease alien plants on flat land were identified depending on where it occurred, and no major trend was found. The cause of these change was driven by unintentionally introduced alien plants. In particular, the cut slope with a high occurence of unintentional ailen plants should not be used as a source of high-risk alien plants such as ecosystem disturbances. Since the transplanted species were intentionally planted by the landscape plan, it was possible to identify colonies from early stages and spread to the nearby flat land. Therefore, in order to minimize the impact of road slope vegetation on the surrounding ecosystem during and after road construction, it is suggested to plant high viability plants in the landscape design during the environmental impact assessment consultation.

• Journal of Conservation Science
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• v.27 no.1
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• pp.31-40
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• 2011

Copper-red (Dongwha, Jinsa) is Korean traditional inorganic pigment used for red-coloring on the porcelain surface during Goryeo and Joseon Periods. Trace amounts of copper-red porcelains are handed down because of the technical difficulty of making and coloring of the pigment. It is known that copper ore sources were extensively distributed in Korea according to old literatures and some of them are still producing copper ore at this present. Main types of copper-bearing mineral in Korea are chalcopyrite ($CuFeS_2$) and malachite ($Cu_2CO_3(OH)_2$), and they are easily collected from the ground surface. This means Korea had geographical and economic geological advantages for supplying raw material of the pigment. These two minerals showed good red-coloring in color test for porcelain pigment. As a coloring element, copper showed micro size less than $5{\mu}m$ in diameter in glaze matrix. The dispersion of copper particle is the most decisive factor for red chromaticity of copper-red porcelain, as well as copper content of the pigment.

• Journal of the Korean Association of Geographic Information Studies
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• v.16 no.4
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• pp.39-53
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• 2013

Although the efficient formation of urban space structure is a key factor in energy saving and environmentally-friendly aspect, the maintenance of the center and sub-center of the city that are key factors has been becoming increasingly difficult due to the variability and complexity of urban activities. In the case of Busan, amid the expansion of urban scale due to rapid economic development and overpopulation, systematic approaches to professional diagnosis and maintenance have been significantly insufficient - other than the city basic plan which has been conducted at an interval of 20 years. For the effective management of urban central area, systematic monitoring of the CBD through demand forecast and blight forecast at a city level must first be implemented. In order to fulfill this goal, this study is to figure out the current state of the CBD through the diagnosis on blight of the urban central area in the viewpoint of rehabilitation of the CBD and to propose the measures for practical utilization of the information about space for the further management of the central area of the city. For analysis, the study looks into the present state in terms of physical index, economic index, and social index. And then as a micro-approach by utilizing economic index, the study has thoroughly examined the economic blight of the Seomyun urban central area of Busan. The outcome of the analysis shows that in terms of population distribution and land utilization the area is in the stage of inefficient dispersion after having gone through the stage of suburbanization. It is expected that this study, as the material that proves the necessity of enhancing the function of the CBD, can propose the direction for the management of the urban center of Busan through blight prediction and management of the urban center and can provide the basic data for the long-term urban development that aims at the efficient strengthening of functions of the CBD.