• Korean Journal of Materials Research
• /
• v.34 no.8
• /
• pp.395-399
• /
• 2024

Among various organic materials suitable for silicon-based inorganic-organic hybrid solar cells, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) has been extensively studied due to its high optical transmittance, high work function, and low bandgap characteristics. The electro-optical properties of PEDOT:PSS have a significant impact on the power conversion efficiency of silicon-organic hybrid solar cells. To enhance the photovoltaic properties of the silicon-organic hybrid solar cells, we developed a method to improve the properties of the PEDOT:PSS film using Ag nanowires (NW) instead of conventional solvent addition methods. The influence of the Ag NW on the electro-optical property of the PEDOT:PSS film and the photovoltaic performance of the silicon-organic hybrid solar cells were investigated. The addition of Ag NW further improved the sheet resistance of the PEDOT:PSS film, enhancing the performance of the silicon-organic hybrid solar cells. The present work using the low sheet resistance PEDOT:PSS layer paves the way to develop simple yet more efficient silicon-organic hybrid solar cells.

• International Journal of Highway Engineering
• /
• v.10 no.1
• /
• pp.87-95
• /
• 2008

One way to shield an atypical structure to secure the occupant safety of an impact vehicle is to stack energy absorbing material modules around the structure. To be applicable to a cushion module, material must have enough energy absorbing capabilities while satisfying the safety requirements of the vehicle occupant. Static compression test of the potential materials gives a good indication which material is good for a slacking module. This paper presents the mechanical properties that a cushion material must have to satisfy the safety requirements. Static tests are performed for Quard-Guard system module, sand bag, recycled tires, Geo-Container, Geo-Cell and Expanded Polystyren (EPS) Blocks. Static test results are discussed and EPS block of $30kg/m^{3}$ density showed good potential for a cushion module. To check the dynamic effect of EPS block, drop tests have been made up to 35.6km/h impact speed. Drop test results are compared with static test results and no appreciable difference was found. To improve the EPS module property, making holes to the block is suggested and drop test are performed for the modified blocks. From the drop test results, design values are suggested.

• Polymer(Korea)
• /
• v.39 no.1
• /
• pp.64-70
• /
• 2015

Thermally expandable microcapsules (TEMs) can be expanded upon heating since the activation energy of liquid hydrocarbon at the core of the TEMs increased at high temperature. Due to this property, TEMs are widely used in the industry as blowing agents or light-weight fillers. In this article, chemical blowing agent and TEM were used for making polypropylene (PP) foams, and their mechanical properties were compared. Physical properties (tensile strength, impact strength etc.) of PP foams decreased with increasing the amount of blowing agents while weight of specimen decreased. However, PP foam produced with TEMs showed higher impact strength than the one with a chemical blowing agent. In order to figure out the difference of impact strength, the morphology of PP foamed was investigated. Expanding properties of TEM can be controlled by changing core back distance.

• Journal of Welding and Joining
• /
• v.30 no.1
• /
• pp.64-71
• /
• 2012

The characteristics of high heat input (342kJ/cm) EG (Electro Gas Arc) welded joint of EH36-TM steel has been investigated. The weld metal microstructure consisted of fine acicular ferrite (AF), a little volume of polygonal ferrite (PF) and grain boundary ferrite (GBF). Charpy impact test results of the weld metal and heat affected zone (HAZ) met the requirement of classification rule (Min. 34J at $-20^{\circ}C$). In order to evaluate the relationship between the impact toughness property and the grain size of HAZ, the austenite grain size of HAZ was measured. The prior austenite grain size in Fusion line (F.L+0.1 mm) was about $350{\mu}m$. The grain size in F.L+1.5 mm was measured to be less than $30{\mu}m$ and this region was identified as being included in FGHAZ(Fine Grain HAZ). It is seen that as the austenite grain size decreases, the size of GBF, FSP (Ferrite Side Plate) become smaller and the impact toughness of HAZ increases. Therefore, the CGHAZ was considered to be area up to 1.3mm away from the fusion line. Results of TEM replica analysis for a welded joint implied that very small size ($0.8\sim1.2{\mu}m$) oxygen inclusions played a role of forming fine acicular ferrite in the weld metal. A large amount of (Ti, Mn, Al)xOy oxygen inclusions dispersed, and oxides density was measured to be 4,600-5,300 (ea/mm2). During the welding thermal cycle, the area near a fusion line was reheated to temperature exceeding $1400^{\circ}C$. However, the nitrides and carbides were not completely dissolved near the fusion line because of rapid heating and cooling rate. Instead, they might grow during the cooling process. TiC precipitates of about 50 ~ 100nm size dispersed near the fusion line.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.12
• /
• pp.3833-3838
• /
• 2009

This paper introduces a measurement system for mechanical properties of sport shoes using an industrial robot. The robot system used in this paper is a commercial Puma type robot system(FARA AT2 made by SAMSUNG Electronics) with 6 joints and the end-effector is modified to produce a human walking motion. After analyzing human walking with a high speed video camera, each joint angle of the robot system is extracted to be used in the robot system. By using this system, ground impact forces were measured during stepping motion with 3 different shoe specimens made of 3 different hardness outsoles, respectively. As other mechanical properties, both bending moments to bend the toe part of the same specimen shoes and pronation quantities during walking motion were measured as well. In the impact test with the same depth of deformation under the ground level, the effect of the outsole hardness was clearly appeared such that the harder outsole produces the higher ground reaction force. The bending test and the pronation test also show proportional increments in the bending stiffness and the moment Mx according to the outsole hardness. Throughout such experiments, the robot system has produced consistent results so that the system could be used in obtaining valuable informations for a shoe designing process.

• Journal of Korean Society of Water and Wastewater
• /
• v.26 no.5
• /
• pp.669-683
• /
• 2012

The water supply pipes are buried across wide range of areas, so it is hard to spot them using excavation and takes a large amount of expense. Thus, there is a high risk for direct research and application, accompanying many difficulties in implementation of them. Therefore, it is more economical and convenient to use indirect evaluation variables than direct evaluation of the buried pipes in assessing the degree of pipe deterioration. To assess the degree of pipe deterioration using the indirect evaluation variables, it should be done first to identify how and to what extent they affect the degree of deterioration. This study measured the evaluation variables for pipe deterioration using the pipe endoscope and analyzed the measurement results and the degree of impact on the pipes. In addition, this study attempted to evaluate the adequateness of the pipe deterioration evaluation using the indirect variables based on the analysis results. The evaluation variables measured through the pipe endoscope were the thickness of sediments, size of scale, degree of desquamation and condition of connections. For the indirect evaluation variables, the data such as the property data from GIS pipe network map as well as the material, diameter, age and pipe lining material of the pipe, road type, leakage frequency, average water velocity and water pressure using the leakage repair records was collected. Using the collected data, this study comparatively analyzed the indirect evaluation variables for the degree of pipe deterioration and the results from the pipe endoscope to choose appropriate variables for pipe deterioration evaluation and calculated the weights of the indirect variables on the degree of deterioration. The results showed that the order of the impact of indirect variables on deterioration was pipe age > pipe lining material > road type > leakage frequency > average water velocity with their weights of 0.45, 0.20, 0.15, 0.10, and 0.10, respectively. Conclusively, the results suggest that the measures of sediment thickness, scale size, degree of desquamation and condition of connections are appropriate for the evaluation of pipe deterioration and sufficient for the analysis of the impact of the indirect variables on deterioration.

• Journal of Environmental Impact Assessment
• /
• v.23 no.5
• /
• pp.323-336
• /
• 2014

Using hedonic price method, this paper analyzes the impact of restriction for water quality protection on property value with the officially announced price of reference land in the city of Namyangju in 2012 to evaluate Water Use Fee, based on beneficiary pays principle, levied on the downstream area of the Han River in Korea. The results from the regression analyses of the models used show that the double-log model is the preferred model in the case of Namyangju. Using the double-log model, the total compensation for the city of Namyangju is estimated to be 8.6 trillion won with 95% confidence interval between 4.4 trillion and 12.4 trillion won. Under the perpetuity compensation scheme at the discount rate of 10%, the estimated annual compensation is 0.9 trillion won with 95% confidence interval between 0.4 trillion and 1.2 trillion won. This is more than Water Use Fee collected in 2012 for the Han River, which is approximately 0.5 trillion won. Considering the size of the restricted area of the Paldang area, which is more than 18 times of that of Namyangju, the rate of Water Use Fee, which is based on beneficiary pays principle and imposed on the residents of the downstream area, needs to be increased to sufficiently compensate the economic loss caused to the upstream areas of the Han River in Korea.

• Applied Chemistry for Engineering
• /
• v.25 no.1
• /
• pp.90-95
• /
• 2014

Nylon66 extrudates as a function of the extrusion number were prepared by a twin screw extruder. Chemical structures, thermal properties, melt index, crystal structures, mechanical properties such as the tensile strength, elongation at break and impact strength, and rheological property were measured by FT-IR, $^1H$-NMR, melt indexer, DSC, TGA, XRD, universal tensile tester, Izod impact tester, and rheometer. FT-IR and $^1H$-NMR characterizations indicated that the number of extrusions did not affect the chemical structure. The decrease in the molecular weight was checked by the melt index of extrudates. There were no effects of the thermal history on the melting and degradation temperature. The tensile and impact strength and modulus were found to be similar, regardless of the number of extrusions, but the elongation decreased significantly. The complex viscosity of extrudates at low frequencies decreased with the extrusion number. No structural changes after extrusion were confirmed from the fact that there was no change in the slope and shape of G'-G" plot.

• Elastomers and Composites
• /
• v.38 no.3
• /
• pp.262-272
• /
• 2003

Maleic anhydride-grafted-polypropylene(PP-g-MA) were used as a blend component and a compatibilizer, respectively, for two reactive blends of polyamide 66(PA 66)PP-g-MA binary blends and PA 66/polypropylene(PP)/PP-g-MA ternary blends. The goal of this work was to investigate the property differences between binary and ternary blends. Tensile strength, flexural modulus, heat deflection temperature, impact strength, melt flow index, and the dependence of melt viscosity on the shear rate were examined. The impact strengths of binary blends were higher than those of ternary blends at all compositions, since the in situ synthesis of PP-g-PA 66 copolymer through the imide formation between the amine end group of PA 66 and the anhydride group of PP-g-MA gave the increase of molecular weight and was more popular in binary blends than in ternary blends. In case of ternary blends, most of the properties were superior to those of binary blends, owing to the better properties of PP compared with PP-g-MA. The toughened binary blends with 70/30(PA 66/PP-g-MA) and 80/20 ratios were not commercially applicable due to their poor processibility. So, the ternary blends which showed lower melt viscosities were recommended for the commercial applications.

• Korean small business review
• /
• v.43 no.1
• /
• pp.51-83
• /
• 2021

This study empirically examined how the technology innovation competence of the 4th Industrial Revolution Enterprises affects management performance. It also analyzed whether there would be any difference in business performance between the 4th Industrial Revolution Enterprises and the non-4th Industrial Revolution Enterprises. The samples for analysis were analyzed using in-situ data of 2,543 enterprises classified as technical innovation enterprises and the 4th Industrial Revolution Enterprises through Korea Technology Finance Corporation's in-house technical evaluation. Variables for technology innovation competence were analyzed using variables such as the size of manpower of research and development, the level of research and development organizations, the number of intellectual property rights, the ratio of intangible assets, the amount of knowledge properties, the amount of research and development investment, and the intensiveness degree of research and development. In terms of the impact of the 4th Industrial Revolution Enterprises' technology innovation competence on business performance, all factors except for the level of research and development organizations were found to affect business performance, which supported the study hypothesis. In particular, it was confirmed that the amount of knowledge properties has had a relatively greater impact on business performance. In addition, the average comparative analysis between the 4th Industrial Revolution Enterprises and the non-4th Industrial Revolution Enterprises confirmed that the 4th Industrial Revolution Enterprises conducted higher values in the business performance.