• Journal of Korean Society of Environmental Engineers
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• v.36 no.11
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• pp.781-790
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• 2014

Contaminants such as organic matters, nutrients and toxic chemicals in rivers and lakes with a weak flow rate are first removed from the water and accumulated in the sediments. Subsequently, they are released into the water column again, posing direct/indirect adverse effects on the water quality and aquatic ecosystems. In particular, phosphorus is known to accelerate the eutrophication phenomenon when it is released into the water column via physical disturbance and biological/chemical actions as one of important materials that determine the primary production of aquatic ecosystems and an element that is stored mainly in the sediments in the process of material circulation in the body of water. In this study, the effect on reducing phosphorus release in sediments was analyzed by applying different capping materials to lake water, where the effect of aquatic microorganisms is taken into account, and to distilled water, where the effect of microorganisms is excluded. The experimental results showed that capping with chemical materials such as Fe-gypsum and $SiO_2$-gypsum further reduced the phosphorus release by at least 40% compared to the control case. Composite materials like granule gypsum+Sand showed over 50% phosphorus release reduction effect. Therefore, it is determined that capping with chemical materials such as granule-gypsum and eco-friendly materials such as sand is effective in reducing phosphorus release. The changes in phosphorus properties in the sediments before and after capping treatment showed that gypsum input helped to change the phosphorus that is present in lake sediments into apatite-P, a stable form that makes phosphorus release difficult. Based on the above results, it is expected that the application of capping technology will contribute to improving the efficiency of reducing phosphorus release that occurs in river and lake sediments.

• Cartoon and Animation Studies
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• s.45
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• pp.283-298
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• 2016

Design is a fatal factor to differentiate and survive one product from the other in fierce competition of the market, when other conditions such as price or quality makes no much difference. Among many marketing tools, package design is known as a direct communication that visualizes and forms the very initial brand image of a product. Package design is not only for packing, transporting, storing and loading but for engraving the brand image in a consumers' mind and lead them to purchasing. One of recent package design trands is various ways of using character, not just as a printed image on the surface but as a part of three dimensional structure of package. If it succeed, the package design could give out the secondary fun and impact to the consumers. The package design with an effective character is itself a great marketing tool and valuable design asset, which can bring a further profit to the company. Especially, character-package can be a powerful and effective marketing method for various local products, in needs of further publication and sales with limited cost. It should motivate the sales of the products by grabbing their attention and taken as a souvenir. This research takes a character package as a useful marketing method for a local brand in Jeonju, South Korea, and tries to design a three dimensional package using its own character. Through the process, the research aims to propose an important design strategy for repositioning or enhancing an existing brand.

• International Journal of Highway Engineering
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• v.6 no.1 s.19
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• pp.47-56
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• 2004

To determine the pure bond strength between substrate and its overlayed concrete material, a direct pull-off test method was introduced by using a bi-material cylinder with which a penny-shaped crack was mountained at its interface. First, to evaluate the stress magnification or concentration at the interface, the energy release rates of a penny-shaped interface crack in remote tension loading on a bi-material cylinder were determined in terms of different modulus ratios and undonded area ratios(crack ratios) using a commercial finite element program. Then the energy release rates were calibrated as non-dimensional values in consideration of structural dimensions and applied forces. And to evaluate whether this new pull-off test method gives sound test results, three different sizes of unbended area ratios were incorporated along their interface in bi-material cylinders(sulphur polymer concrete + old concrete). Test results showed that all specimens were broken off at their interfaces as intended. Also the FEM analyses and test results indicated that a bi-material specimen with unbended area ratio of 0.4$\sim$0.6 is suitable for best accurate testing.

• Korean Chemical Engineering Research
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• v.43 no.1
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• pp.118-124
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• 2005

In this study, a novel deposition method of Pt catalysts onto Nafion membranes modified with polypyrrole (PPy) has been proposed for PEMFC application. The PPy/Nafion composite membranes were fabricated by chemical polymerization of pyrrole using $FeCl_3$ and $Na_2S_2O_8$ as initiator. The proton conductivity and water uptake of the chemically prepared PPy/Nafion composites were investigated. The ionic conductivity and water uptake of PPy/Nafion composite membrane prepared with $Na_2S_2O_8$ were decreased with polymerization time of pyrrole. In the case of $FeCl_3$, the ionic conductivity was almost retained and the water uptake was decreased with polymerization time of pyrrole. When the Pt particle was deposited on PPy/Nafion composites membrane by chemical reduction of $H_2PtCl_6$, the Pt loading on Nafion membrane was enhanced by polypyrrole due to electronic conduction property. The performance evaluation with membrane electrode assembly composed of Pt/PPy/Nafion composite and diffusion electrode was carried out using a single cell. As a result of fuel cell test, current density of $569mA/cm^2$ at 0.3 V has been obtained for MEA contained with Pt/PPy/Nafion composite. This study shows that direct deposition of Pt catalysts on Nafion impregnated polypyrrole is a promising method to prepare thin catalyst layer for the PEMFC.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.2
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• pp.201-212
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• 2012

There are some similar aspects at histological and morphological characteristics between the peri-implant tissue and periodontal tissue and the direct attachment between the titanium and soft tissue around the implant called as "Functional ankylosis" can prevent the apical infiltration of inflammatory and bone resorption around implant. But, the repeated connection and disconnection of the abutment can destroy the mucosal barrier of soft tissue around the implant and can cause the marginal bone resorption. The amount of marginal bone resorption may reduced if the prosthetic abutment is placed at that time of surgery. Connection of the prosthetic abutment at surgery was limited because the low accuracy of conventional method, but by using of Cone Beam Computed Tomography(CBCT) and guide surgery, the 3-dimensional accuracy of implant placement became much higher than before and it became possible. This is a clinical case of immediate connection of prosthetic abutment and provisional restoration by using of precise CBCT diagnosis and pre-fabricated zirconia customized abutment at surgery and the alternative method is described in this article because of the clinically contentable results.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.177-181
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• 2012

Dye-sensitized solar cells(DSSCs) based on $TiO_2$ film photo anode incorporated with different amount of grapheme nanosheet(GNS) are fabricated and their photovoltaic performance are investigated. The $TiO_2$-GNS composite electrode has been prepared by a direct mixing method. The DSSC performance of this composite electrode was measured using N3 dye as a sensitizer. The performance of DSSCs using the $TiO_2$-GNS composite electrodes is dependent on the GNS loading in the electrodes. The results show that the DSSCs incorporating 0.01 wt% GNS in $TiO_2$photo anode demonstrates a maximum power conversion efficiency of 5.73%, 26% higher than that without GNS. The performance improvement is ascribed to increased N3 dye adsorption, the reduction of electron recombination and back transport reaction as well as enhancement of electron transport with the introduction of GNS. The presence of both $TiO_2$(anatase) and GNS has been confirmed by FieldEmission Scanning Electron Microscopy(FE-SEM). The decrease in recombination due to GNS in DSSCs has been investigated by the Electrochemical Impedance Spectroscopy.

• Journal of the Korea Concrete Institute
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• v.24 no.2
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• pp.205-214
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• 2012

Crack widths play an important role in the serviceability limit state. When crack widths are controlled sufficiently, the reinforcement corrosion can be reduced using only existing concrete cover thickness due to low permeability in the region of finely distributed hair-cracks. Thus, the knowledge about the tensile crack opening is essential in designing more durable concrete structures. Therefore, numerous researches related to the topic have been performed. Nevertheless accurate measurement of a crack width is not a simple task due to several reasons such as unknown potential crack formation location and crack opening damaging strain gages. In order to overcome these difficulties and measure precise crack widths, a displacement measurement system was developed using digital image correlation. Accuracy calibration tests gave an average measurement error of 0.069 pixels and a standard deviation of 0.050 pixels. Direct tensile test was performed using ultra high performance concrete specimens. Crack widths at both notched and unnotched locations were measured and compared with clip-in gages at various loading steps to obtain crack opening profile. Tensile deformation characteristics of concrete were well visualized using displacement vectors and full-field displacement contour maps. The proposed technique made it possible to measure crack widths at arbitrary locations, which is difficult with conventional gages such as clip-in gages or displacement transducers.

• Spatial Information Research
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• v.12 no.2
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• pp.181-191
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• 2004

Nowadays, GPS-photogrammetry can be applied to the basemap production, a land register and NGIS. And from now on, as the increase of GPS receiver rate, the study on the interpolation methods considering the exact movement of an aircraft at photoflight and the study on the supplement of GPS defect by INS are required continuously. GPS-Photogrammetry, which are based on the direct measurement of the projection centers and attitude at the moment of camera exposure time through loading the GPS receiver in aircraft. This photogrammetric methods can of for us to acquire the exterior orientation parameters with only minimum ground control points, even the ground control process could be completely skipped. Consequently, we can drastically reduce the time and cost far the mapping process. In this thesis, two test flights were conducted in area to evaluate the performance of accuracy and efficiency through the analysis of results between the two photogrammetric methods, that is, traditional photograrammetry, GPS-Photogrammetry. Test results shows that a large variety of advantages of GPS-Photogrammetry against traditional photogrammetry is to be verified. Especially, the number of ground control points for the exterior orientation could be saved more than 70～80%, and the cost far map production 30～50%, respectively. In addition, it was convinced that the large reduction of control points has not any effect on the block accuracy.

• Polymer(Korea)
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• v.26 no.5
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• pp.691-700
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• 2002

Interstitial therapy using biodegradable polymeric device loaded with anticancer agent can deliver the drug to the tumor site at high concentration, resulting in an increase of therapeutic efficacy. 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU, carmustine) is most commonly used as chemotherapeutic agent for brain tumors. The design of implantable device is regarded as an important factor lot the efficient delivery of antitumor agent to targeting site. In order to control the release profile of drug, the release pattern of BCNU with the changes of various dimension and additives was investigated. The PLGA wafers containing 3.85, 10, 20 and 30% of BCNU were prepared in various shape (diameter of 3, 5 and 10 mm, thickness of 0.5, 1 and 2 mm) by direct compression method. In vitro drug release profile of BCNU-loaded PLGA wafers could be controlled by changing the dimension of wafers such as initial drug content, weight, diameter, thickness, volume and surface area of wafers, as well as PLGA molecular weight and additives. Drug release from BCNU-loaded PLGA wafers was facilitated with an increase of BCNU-loading amount or presence of poly(N-vinylpyrrolidone)(PVP) or sodium chloride (NaCl). The effects of various geometric factors and additives on the BCNU release pattern were confirmed by the investigation of mass loss and morphology of BCNU-loaded PLGA wafers.

• Tunnel and Underground Space
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• v.26 no.3
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• pp.220-234
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• 2016

Sprayable waterproofing membrane has been considered as a substitute for a sheet waterproofing membrane in a variety of underground excavation works. However, fundamental properties of sprayble waterproofing membrane have not been fully given yet. In this study, a new two-component sprayable waterproofing membrane prototype was developed. In addition, its physico-mechanical properties were measured and compared with those of two kinds of thin spray-on liners where constitutive materials and construction methods are very close to each other. From direct tensile tests, the sprayable waterproofing membrane with elongations at break between 250% and 300% showed much higher ductility than TSLs. However, the sprayable waterproofing membrane had a limitation as a support member since its bond strength and loading capacity was lower than those of TSLs. From three-dimensional X-ray CT images, the porosity of the sprayable waterproofing membrane was estimated to be 26.13%. However, most of pores which might have been generated during membrane curing were not observed to be interconnected but isolated.