• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.14 no.2
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• pp.69-78
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• 1978

It is well known that the aluminizing steel is excellent in corrosion resistance and heat resistance. Therefore it has been used as boiler parts, heat exchanger parts and guide rails which are used under comparatively simple conditions. Recently, it has been noticed that aluminizing steel has high resistance to various atmosphere, high temperature oxidation and seawater resistance. So its usage has been extended widely to the production of parts such as intake and exhaust valve of internal combustion engine, turbine blade and pipelines On ships which required such properties. It is considered that aluminium coated steel is excellent in wear resistance because of high hardness on main ingredient FezAIs of Fe-AI alloy layer existed in diffusion coating layer. And it will beused as a new material taking wear resitance with seawater resistance in marine field. However it is difficult to findout any report concering the wear behaviors or properties of alum in izing steel. In this study the experiment was carried out under the condition of rolling-sliding contact using an Amsler-type wear testing machine at 0.80, 0.91, 1. 10, 1. 25% of slip ratio and 55.43, 78.38, 110.85 kg/mm^2 of Hertz's contact stress in run-in period for the purpose of service-ability test of aluminizing steel as a wear resisting material and obtaining the available design data. The followings are the obtained results from the experimen tal study; 1) The 2nd diffusion material has most excellent wear resistance. This material has brought out about 18% decrease of wear weight in a lower friction load level and 40~G decrease in a higher level comparing to the raw material. 2) Satisfactory effect of wear resistivity cannot be much expected in 2nd diffusion specimens. This is considered due to the formation of fine void in the alloy layer near the boundary to the aluminium layer. 3) Fracture on friction surface of aluminizing steel by the rolling-sliding contact is spalling, and spalling crack occurres initially beneath the specimen surface near the boundary in diffusion coating layer.

• The Journal of the Korea Contents Association
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• v.15 no.12
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• pp.61-72
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• 2015

The capitalistic resistance movement attempted in most modern art areas was carried out through a complete convergence of the art and skill, which was the new formation of the symbolic boundary. Although this resistance movement was aimed at restoring artisan art through the revival of tbe work of handicraftsmen, it consequently caused the stratification of the art and became a de-artisan art excluding the autonomous labor. Hereupon, this study would focus on Bauhaus which attempted to dismantle the symbolic boundary through the convergence of the technology and art which actively used the condition the great industry brought only as an effort for the restoration of artisan labor, and would examine the actor-network of Bauhaus. Therefore, this study would examine the Bauhaus' artistic trend, the 16C Renaissance art promotion movement, and the 19C art crafts movement in the network-oriented relation, and would analyze the Bauhaus' ideological source which expressed design democracy through the bridging role of and analyze the artisan art and the mechanism that had the new technology fused. Furthermore, the convergence possibility of the 'collaboration spirit' being embodied as a philosophy of the democracy in the design continues with the tremendous influence of the new technology.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.2
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• pp.47-53
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• 2014

Three kinds of crystalline silicon have been used for the solar cell grade. First of all, single crystalline silicon is the main subject to enhance the production yield. Most of the efforts are focused on the control of the melt-crystal interface shape affected by the crystal-crucible rotation rate. The main subject in the multi-crystalline silicon ingot is the contamination control. Faster Ar gas flow above the melt surface will lower the carbon contamination in the crystal. And also, twin boundary electrically inactive is found to be more effective than grain boundary for the improvement of the MCLT. In the case of mono-like silicon material, propagation of the multi-crystalline silicon growing from the inner side crucible is the problem lowering the portion of the single crystalline part at the center of the ingot. Crystal growing apparatus giving higher cooling rate at the bottom and lower cooling rate at the side crucible was suggested as the optimum solution obtaining higher quality of the mono-like silicon ingot. Proper application of the seeds at the bottom of the crucible would be one of the solutions.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.22 no.3
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• pp.253-259
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• 2004

The sheetwise cadastral map data needs to become a Serial Cadastral Map (SCM) database for the promotion of the reliability of cadastral surveying, for the efficient operation of the Parcel Based Land Information System, and for the convenient use of land information as well. A large amount of money and time are required for the editing process of producing SCM DB in accordance with the $\ulcorner$Guideline for the Production of Serial Cadastral Maps$\lrcorner$ by the Ministry of Construction & Transportation if any of field surveying techniques is accompanied by. In addition, a boundary line that extends to a neat line does not meet the counterpart of the neighboring map sheet at a point. Such cases frequently occur and are much dependent upon the decisions of individuals in charge of editing or inspecting. The core processes of the research, firstly overlay SCM produced by the edition of the sheetwise cadastral maps with Autodesk Map on orthophoto images, secondly adjust the parcel boundaries which are delineated over more than one map sheet, and lastly compare the original boundary coordinates and areas with the corresponding adjusted ones and calculate root mean square errors (RMSEs). The research aims at promoting the quality of SCM by minimizing the inconsistency of parcel boundaries by means of the comparative analysis of the calculated RMSEs.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.38 no.2
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• pp.108-117
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• 2020

This study takes the Gyeongju Historic Areas Daereungwon Area as the research object, uses the Virtual Walkthrough method for virtual experience and evaluation, the visual characteristics were analyzed. To analyze landscape visual characteristics and to find out the relationship between image factors and visual preferences, the factor analysis and multiple regression analysis were conducted. The results are as follows: the results of preference analysis of the Daereungwon Area show that the preference of scene3 where located on the western boundary of Noseo-rl tumuli got the highest score, and the preference score of scene5 where located on the western boundary of Daereungwon less than three points. The results of factor analysis of visual characteristics, three factors were analyzed: regularity factor, spatiality factor and historical factor. The analysis of variance and multiple regression analysis results of the relationship between factor scores and visual preferences show that regularity factor was analyzed as the biggest factor that affects the visual preference of the Historical-cultural landscape Daereungwon Area. Virtual Walkthrough method has a strong three-dimensional and strong production of the real landscape scene, it's an effective method in landscape analysis. The results of research provides data and information for improving the visual quality of Historical-cultural landscape and it's expected to be applied in the future of landscape planning.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.23 no.1
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• pp.32-48
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• 2018

The mechanisms of $CH_4$ uptake into and release from the ocean are not well understood due mainly to complexity of the biogeochemical cycle and to lack of regional-scale and/or process-scale observations in the marine boundary layers. Without complete understanding of oceanic mechanisms to control the carbon balance and cycles on a various spatial and temporal scales, however, it is difficult to predict future perturbation of oceanic carbon levels and its influence on the global and regional climates. High frequency, high precision continuous measurements for carbon isotopic compositions from dissolved $CH_4$ in the surface ocean and marine atmosphere can provide additional information about the flux pathways and production/consumption processes occurring in the boundary of two large reservoirs. This paper introduces recent advances on optical instruments for real time $CH_4$ isotope analysis to diagnose potential applications for in situ, continuous measurements of carbon isotopic composition of dissolved $CH_4$. Commercially available, three laser absorption spectrometers - quantum cascade laser spectroscopy (QCLAS), off-axis integrated cavity output spectrometer (OA-ICOS), and cavity ring-down spectrometer (CRDS) are discussed in comparison with the conventional isotope ratio mass spectrometry (IRMS). Details of functioning and performance of a CRDS isotope instrument for atmospheric ${\delta}^{13}C-CH_4$ are also given, showing its capability to detect localized methane emission sources.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.75.2-75.2
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• 2010

Polymer electrolyte fuel cells (PEFCs) have received a lot of attention as a power source for both stationary and mobile applications due to their attractive feature. In general, the performance of PEFCs is highly affected by the property of the electrodes. A PEFC electrode essentially consists of a gas diffusion layer and a catalyst layer. The gas difusion layer is highly porous and hydrophobicized with PTFE polymer. The catalyst layer usually contains electrocatalyst, proton conducting polymer, even PTFE as additive. Particularly, the proton conducting ionomer helps to increase the catalytic activity at three-phase boundary and catalyst utilization. Futhermore, it helps to retain moisture, resulting in preventing the electrodes from membrane dehydration. The most widely used proton conducting ionomer is perfluorinated sulfonic acid polymer, namely, Nafion from DuPont due to its high proton conductivity and good mechanical property. However, there are great demands for alternative ionomers based on non-fluorinated materials in terms of high temperature availability, environmental adaptability and production cost. In this study, the electrodes with the various content of the sulfonated poly(ether sulfone) ionomer in the catalyst layer were prepared. In addition, we evaluated electrochemical properties of the prepared electrodes containing the various amount of the ionomers by using the cyclic voltammetry and impedance spectroscopy to find an optimal ionomer composition in the catalyst layer.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.1
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• pp.111-119
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• 2015

The negative factors of fishery in environmental aspect of view are Greenhouse gas emission problems by high usage of fossil fuel, destruction of underwater ecosystem by bottom trawls, reduction of resources by fishing and damage of ecosystem diversity. Especially, the Greenhouse gas emission from fisheries is an important issue due to Canc$\acute{u}$n meeting, Mexico in 1992 and Kyoto protocol in 2005. However, the investigation on the GHG emissions from Korean fisheries did not much carry out. Therefore, the quantitative analysis of GHG emissions from Korean fishery industry is needed as a first step to find a relevant way to reduce GHG emissions from fisheries. The purpose of this research is to investigate which degree of GHG emitted from fishery. Here, we calculated the GHG emission from Korean bottom pair trawl fishery using the LCA (Life Cycle Assessment) method. The system boundary and input parameters for each process level are defined for LCA analysis. The fuel use coefficient of the fishery is also calculated. The GHG emissions from the representative fishes caught by bottom pair trawl will be dealt with. Furthermore, the GHG emissions for the edible weight of fishes are calculated with consideration to the different consuming areas and slaughtering process also. The results will be helpful to understand the circumstances of GHG emissions from Korean fisheries.

• Advances in concrete construction
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• v.9 no.3
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• pp.235-248
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• 2020

Progressive collapse in a structure occurs when load bearing members are failed and the adjoining structural elements cannot resist the redistributed forces and fails subsequently, that leads to complete collapse of structure. Recently, construction using precast concrete technology is adopted increasingly because it offers many advantages like faster construction, less requirement of skilled labours at site, reduced formwork and scaffolding, massive production with reduced amount of construction waste, better quality and better surface finishing as compared to conventional reinforced concrete construction. Connections are the critical elements for any precast structure, because in past, major collapse of precast structure took place because of connection failure. In this study, behavior of four different precast wet connections with U shaped reinforcement bars provided at different locations is evaluated. Reduced 1/3^rd scale precast beam column assemblies having two span beam and three columns with removed middle column are constructed and examined by performing experiments. The response of precast connections is compared with monolithic connection, under column removal scenario. The connection region of test specimens are filled by cast-in-place micro concrete with and without polypropylene fibers. Performance of specimen is evaluated on the basis of ultimate load carrying capacity, maximum deflection at the location of removed middle column, crack formation and failure propagation. Further, Finite element (FE) analysis is carried out for validation of experimental studies and understanding the performance of structural components. Monolithic and precast beam column assemblies are modeled using non-linear Finite Element (FE) analysis based software ABAQUS. Actual experimental conditions are simulated using appropriate boundary and loading conditions. Finite Element simulation results in terms of load versus deflection are compared with that of experimental study. The nonlinear FE analysis results shows good agreement with experimental results.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.96-96
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• 2016

Nanotechnology mostly employs nano-materials and nano-structures with distinctive properties based on their size, structure, and composition. It is quite difficult to produce nano-materials and nano-structures with identical sizes, structures, and compositions in large quantities, because of spatiotemporal fluctuation of production processes. In other words, fluctuation is the bottleneck in nanotechnology. We propose three strategies to suppress such fluctuations: employing 1) difference between linear and nonlinear phenomena, 2) difference in time constants, and 3) nucleation as a bottleneck phenomenon. We are also developing nano- and micro-scale guided assembly using plasmas as a plasma nanofabrication.1-5) We manipulate nano- and micro-objects using electrostatic, electromagnetic, ion drag, neutral drag, and optical forces. The accuracy of positioning the objects depends on fluctuation of position and energy of an object in plasmas. Here we evaluate such fluctuations and discuss the mechanism behind them. We conducted in-situ evaluation of local plasma potential fluctuation using tracking analysis of fine particles (=objects) in plasmas. Experiments were carried out with a radio frequency low-pressure plasma reactor, where we set two quartz windows at the top and bottom of the reactor. Ar plasmas were generated at 200 Pa by applying 13.56MHz, 450V peak-to-peak voltage. The injected fine particles were monodisperse methyl methacrylate-polymer spheres of $10{\mu}m$ in diameter. Fine particles were injected into the reactor and were suspended around the plasma/sheath boundary near the powered electrode. We observed binary collision of fine particles with a high-speed camera. The frame rate was 1000-10000 fps. Time evolution of their distance from the center of mass was measured by tracking analysis of the two particles. Kinetic energy during the collision was obtained from the result. Potential energy formed between the two particles was deduced by assuming the potential energy plus the kinetic energy is constant. The interaction potential is fluctuated during the collision. Maximum amplitude of the fluctuation is 25eV, and the average is 8eV. The fluctuation can be caused by neutral molecule collisions, ion collisions, and fluctuation of electrostatic force. Among theses possible causes, fluctuation of electrostatic force may be main one, because the fine particle has a large negative charge of -17000e and the corresponding electrostatic force is large compared to other forces.