• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.587-598
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• 2008

In the trackbed design using elastic multi-layer model, the stress-dependent resilient modulus is an important input parameter, which reflects substructure performance under repeated traffic loading. The resilient moduli of crushed stone and weathered granite soil were developed using nonlinear dynamic stiffness, which can be measured by in-situ and laboratory seismic tests. The prediction models of resilient modulus varying with the deviatoric or bulk stress were proposed (Park et al., 2008). To investigate the performance of the prediction models proposed herein, the elastic response of the test trackbed near PyeongTaek, Korea was evaluated using a 3-D nonlinear elastic computer program (GEOTRACK) and compared with measured elastic vertical displacement during the passages of freight and passenger trains. The material types of the test sub-ballasts are crushed stone and weathered granite soil, respectively. The calculated vertical displacements within the sub-ballasts are within the order of 1mm, and agree well with measured values with the reasonable margin. The prediction models are thus concluded to work properly in the preliminary investigation. The prediction models proposed for resilient modulus were verified by the comparison of the calculated vertical displacements with measured ones during train passages.

• Journal of Ocean Engineering and Technology
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• v.34 no.1
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• pp.1-12
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• 2020

Although there are many kinds of advanced ballast water management systems, pioneering studies for ballast-water free ship and minimal ballast water ship concepts are in progress. In this study, the existing alternatives of ballast water are reviewed and a new design concept is studied on the basis of the existing bulk carrier hull form. To develop a new design alternative which has minimal ballast for ballast water discharge free operation, the new concept should have technical feasibilities that are related to the role of the ballast water, berth access, loading constraints, etc. For this purpose, a simplified systems engineering basis design approach is adopted using a business model as the system analysis and control tool. To check the performance feasibility of the new concept, ship resistance performance is reviewed based on a model scale ship resistance performance analysis.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.537-543
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• 2003

This paper presents the improved procedure to assess static and dynamic strength of crawler type excavators. A fully integrated model including front attachment and chassis was prepared for structural analysis. In this paper, two types of loading input methods were investigated and the method imposing digging force directly on bucket tooth was more convenient than imposing cylinder reaction force on cylinder pin even if the two methods showed no discrepancy in analysis results. Static strength analysis was carried out for eight analysis scenarios based on two extreme digging positions, maximum digging reach position and maximum digging force positions. The results from static strength analysis were compared with measured stresses, cylinder pressures and digging forces and showed a good quantitative agreement with measured data. Dynamic strength analysis was carried out for simple reciprocation of boom cylinders. It was recognized that the effect of compressive stiffness of hydraulic oil was very important for dynamic structural behavior. The results from dynamic strength analysis including hydraulic oil stiffness were also compared with measured acceleration data and showed a qualitative agreement with measured data.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.5
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• pp.15-21
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• 2015

The glass used for Mobile Camera Window is required to have high strength. Cell type manufacturing by means of CNC is widely used for camera window. Individual loading and unloading is needed for each process, such as painting and PVD, in cell type manufacturing. The purpose of this study is to search the enhanced manufacturing process with sheet type throughout bulk unit production in painting and PVD. This study includes sheet type manufacturing processes such as laser cutting, wet etching, 2nd tempering, printing, and AF/AR coating.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.4 no.4
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• pp.201-208
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• 2000

The reduction of NO by hydrocarbons was investigated over Cu/Al$_2$O$_3$catalysts using a stainless steel flow reactor under highly oxidising diesel exhaust conditions(up to 15%). Three different Cu loadings(1,5 and 10wt.%) on an $Al_2$O$_3$support were prepared and characterized using spectroscopic techniques. The catalytic activity tests show that different Cu loadings as well as temperature, oxygen, and hydrocarbon concentration levels significantly influence the NO reduction. Increasing Cu loadings up to 5 and 10wt.% decreases the catalytic activities for NO reduction due to the formation of a bulk crystalline CuO phase, as observed from XRD and SEM images. In particular, the visualization of the copper dispersion on the surface using the SEM-BEI technique provides information on the extent of copper saturation, particle size, and the effects on NO reduction. However, the lower Cu loading(1 wt.%) increases the catalytic activity with a temperature window of 720-810K, thereby favoring the formation of well dispersed isolated Cu species, e.g. Cu(sup)2+ ions, which is related to selective NO reduction. The effects of other reaction parameters, such as oxygen, the hydrocarbon level and type, and byproduct emissions are further discussed.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.160.1-160.1
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• 2014

Using a density functional theory calculation including van der Waals (vdW) corrections, we report that $H_2$ adsorption in a cubic-crystalline microporous metal-organic framework (MOF-5) leads to volume shrinkage, which is in contrast to the intuition that gas adsorption in a confined system (e.g., pores in a material) increases the internal pressure and then leads to volumetric expansion. This extraordinary phenomenon is closely related to the vdW interactions between MOF and $H_2$ along with the $H_2$-$H_2$ interaction, rather than the Madelung-type electrostatic interaction. At low temperatures, $H_2$ molecules adsorbed in the MOF-5 form highly symmetrical interlinked nanocages that change from a cube-like shape to a sphere-like shape with $H_2$ loading, helping to exert centrosymmetric forces and hydrostatic (volumetric) stresses from the collection of dispersive interactions. The generated internal negative stress is sufficient to overcome the stiffness of the MOF-5 which is a soft material with a low bulk modulus (15.54 GPa).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.10
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• pp.1048-1053
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• 2002

In this paper, thin film bulk acoustic resonator(TFBAR) lattice and balanced type filter topologies are designed and fabricated. Aluminium nitride and platinum are used for piezoelectric material and top and bottom electrodes, respectively. Air-gap is placed to avoid silicon substrate loading effect and the performance of these lattice and balanced filters is compared with ladder filters. These filters have selectivity over 15 dB for lattice type and 30 dB for balanced type and reveal wider bandwidth of the ladder filters. For balanced type filters, minor tuning procedure is not needed and they are readily available for RF filter in wireless applications.

• International Journal of Naval Architecture and Ocean Engineering
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• v.5 no.3
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• pp.454-467
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• 2013

A practical Ship Inner Shell Optimization Method (SISOM), the purpose of which is to improve the safety of the seagoing transport ship by decreasing the maximum Still Water Bending Moment (SWBM) of the hull girder under all typical loading conditions, is presented in this paper. The objective of SISOM is to make the maximum SWBM minimum, and the section areas of the inner shell are taken as optimization variables. The main requirements of the ship performances, such as cargo hold capacity, propeller and rudder immersion, bridge visibility, damage stability and prevention of pollution etc., are taken as constraints. The penalty function method is used in SISOM to change the above nonlinear constraint problem into an unconstrained one, which is then solved by applying the steepest descent method. After optimization, the optimal section area distribution of the inner shell is obtained, and the shape of inner shell is adjusted according to the optimal section area. SISOM is applied to a product oil tanker and a bulk carrier, and the maximum SWBM of the two ships is significantly decreased by changing the shape of inner shell plate slightly. The two examples prove that SISOM is highly efficient and valuable to engineering practice.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1712-1723
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• 2008

In the trackbed design using an elastic multi-layer model, the stress-dependent resilient modulus is the key input parameter, which reflects substructure performance under repeated traffic loading. The prediction models of resilient modulus of crushed stone and weathered granite soil were developed from nonlinear dynamic stiffness, which can be combined by in-situ and laboratory seismic measurements. The models accommodate the variation with the deviatoric and/or bulk stresses. To investigate the performance of the prediction models proposed, the elastic response of the test trackbed near PyeongTaek, Korea was evaluated using a 3-D nonlinear elastic computer program (GEOTRACK) and compared with measured elastic vertical displacement caused by the passages of freight and passenger trains. The material types of the test sub-ballasts are crushed stone and weathered granite soil, respectively. The calculated vertical displacements within the sub-ballasts are within the order of 1mm, and agree well with measured values with the reasonable margin. The prediction models are thus concluded to work properly in the preliminary investigation.

• Restorative Dentistry and Endodontics
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• v.10 no.1
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• pp.71-83
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• 1984

The purpose of this study was to evaluate the transmission spectrum of the set calcium hydroxide dental cement (Dycal, L.D. Caulk Co. Milford, Del.) Cement was prepared for A T R spectra at a low powder-to-liquid ratio of 3.0gm/ml in order to retard the reaction and facilitate the manipulation of loading the cement into the cell. Spectra were recorded on an I R Spectrophotometer (MX-1, FT) at an agle of incidence of 55. The A T R cell was a RIIc Model TR5 with a hemisperical KRS-5 (Thallium-Bromide-Iodide). A spectrum was recorded within 3 minutes. Further spectra were recorded after 5,10,30 minutes and 1,5,24, 72 hours. The results were as follows; 1. The setting reaction between acid paste and base past would take place fastly within 10 minutes after mix, and that would be slow until 72 hours after mix. 2. In the set cements, some methyl salicylate and calcium hydroxide remained unreacted until 72 hours after mix. 3. The setting reaction and the reaction rate occuring at the surface and in the bulk cements were similar. 4. The chelates were bound together between calcium hydroxide and methyl salicylate.