• Journal of Korea Water Resources Association
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• v.57 no.10
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• pp.711-723
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• 2024

Water distribution systems are important large-scale social infrastructure facilities for maintaining human society. Large-scale social infrastructure facilities are increasing due to urbanization and industrialization. However, one of the problems caused by the progress of urbanization and industrialization is carbon dioxide (CO₂) emissions. In this study, a Life Cycle Carbon Emission Analysis (LCCEA) model was proposed to analyze the amount of CO₂ generated during the life cycle of water distribution systems, such as installation, maintenance, and repair. Based on the proposed LCCEA model, low-carbon optimal design was performed and compared with cost-optimal design. As a result of applying the LCCEA model to domestic and international water distribution systems, the low-carbon optimal design showed a decrease in total and annual CO₂ emissions compared to the cost-optimal design. In addition, when CO₂ emissions were converted to costs and compared, the low-carbon optimal design showed better results in terms of cost. The LCCEA model can be applied to various water distribution systems as well as domestic and international water supply networks used in this study, and it will show good results in the design and operation of water distribution systems.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.11
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• pp.1767-1776
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• 2001

For the stable operation of high speed air spindle, the low rotational inertia and high damping ratio of spindle shafts as well as high fundamental natural frequency are indispensable. Conventional steel spindles are net appropriate for very high speed operation because of their high rotational inertia and low damping ratio. In this study, a high speed spindle composed of carbon fiber epoxy composite shaft and steel flange was designed for maximum critical speed considering minimum static deflection and radial expansion due to bending load and centrifugal force during high speed relation. The stacking angle and the stacking thickness of the composite shaft and the adhesive bonding length of the 7teel flange were selected through vibrational analysis considering static and thermal loads due to temperature rise.

• Journal of KIBIM
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• v.5 no.4
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• pp.11-22
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• 2015

Government efforts for green growth policy initiatives demand low-carbon technologies in the road construction industry. The purpose of this paper is to develop an algorithm of a road alignment design solution for establishing the multi-dimensional information, and to calculate carbon emission quantity due to the geometric design elements in the planning phase of road alignment. The paper developed a calculation method for carbon emission quantity by drawing a speed profile reflected in the operating speed, acceleration and deceleration, which are majors factor of carbon emissions while driving and by applying a carbon emission factor. From this effort, it enabled alignment planning to reduce carbon emission. Object-based parametric design methods of the cross-sections were proposed for alignment planning, and the paper demonstrated a BIM-based road alignment planning solution. The proposed solutions can provide multi-dimensional information on carbon emission quantity and cross section elements through driving simulation. It is expected to allow construction of eco-friendly roads by deriving optimal road alignment to minimize environmental costs.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.3
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• pp.7-13
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• 2019

Recently, an automobile market used to natural gas has emerged as fast-growing as the several countries, who holds abundant natural fuel resources, has promoted to supply the national agency for an automobile car. LNG fuel vessel is more efficient in another way as the energy density is high, but it requires a high technology and investment to maintain extreme low temperature. CNG fuel vessel are relatively low-cost alternative to LNG, but poorly economical in terms of energy density as well as showing safety issues associated with compressed pressure. The development of adsorbed natural gas (ANG) has emerged as one of potential solutions. Therefore, it is desirable to reduce the weight of vessel by applying light-weighed a composite carbon fiber in order to response to the regulation of $CO_2$ emission. Herein, this study make the prototype ANG vessel not only based on the optimal design and analysis of material characteristic but also based on the shape design, and it suggest a new type for the composite carbon fiber vessel which verified functional test. Moreover, the detail shape design is analyzed by a finite element analysis, and its verifies the ANG vessel.

• Journal of computational fluids engineering
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• v.14 no.1
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• pp.78-85
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• 2009

A combined theoretical and numerical study is conducted to design a slit nozzle for large-area liquid coating. The objectives are to guarantee the uniformity in the injected flow and to provide the capability of explicit control of flow rate. The woking fluid is a dilute aqueous solution containing single-walled carbon nanotubes and its low viscosity and the presence of dispersed materials pose technical hurdles. A theoretical analysis leads to a guideline for the geometric design of a slit nozzle. The CFD-based numerical experiment is employed as a verification tool. A new flow passage unit, connected to the nozzle chamber, is proposed to permit the control of flow rate by using the commodity pressurizer. The numerical results confirm the feasibility of this idea. The optimal geometry of internal structure of the nozzle has been searched for numerically and the related issues are discussed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.107-108
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• 2021

In the global trend of countries around the world announcing the declaration of carbon neutrality, the development of low-carbon cement in the cement industry can be seen as a very important issue that can determine the future development of the cement industry in the future. Therefore, this study evaluated the strength characteristics of limestone cement paste with limestone powder of CaCO3 and refinery desulfurization waste catalyst of high Al₂O₃ content, and using a Minitab mixture design to optimize a limestone cement content. As a resuls it was confirmed that limestone cement paste with 5-10% of limestone powder and 1.25-2.5% of the waste catalyst exhibits similar compressive strength to that of OPC.

• Journal of Korean Society of Water and Wastewater
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• v.37 no.6
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• pp.335-345
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• 2023

In Korea, as part of the Green New Deal project toward a carbon-neutral society, it is necessary to build a climate-resilient urban environment to green the city, space, and living infrastructure. To this end, SWMM-ING was improved and the model was modified to analyze the carbon reduction effect. In addition, I plan to select target watersheds where urbanization is rapidly progressing and evaluate runoff, non-point pollution, and carbon reduction effects to conduct cost estimation and optimal design review for domestic rainwater circulation green infrastructure. In this study, green infrastructure facilities were selected using SWMM-ING. Various scenarios were presented considering the surface area and annual cost of each green infrastructure facility, and The results show that the scenario derived through the APL2 method was selected as the optimal scenario. In this optimal scenario, a total facility area of 190,517.5 m² was applied to 7 out of 30 subwatersheds to achieve the target reduction. The target reduction amount was calculated a 23.50 % reduction in runoff and a 26.99 % reduction in pollutant load. Additionally, the annual carbon absorption was analyzed and found to be 385,521 kg/year. I aim to achieve additional carbon reduction effects by achieving the goal of reducing runoff and non-point pollution sources and analyzing annual carbon absorption. Moreover, considering the scale-up of these interventions across the basin, it is believed that an objective assessment of economic viability can be conducted.

• Journal of Sensor Science and Technology
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• v.30 no.4
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• pp.250-254
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• 2021

A highly sensitive and selective non-dispersive infrared (NDIR) carbon dioxide gas sensor requires achieving high transmittance and narrow full width at half maximum (FWHM), which depends on the interface of the optical filter for precise measurement of carbon dioxide concentration. This paper presents the design, simulation, and fabrication of a Fabry-Perot filter based on a distributed Bragg reflector (DBR) for a low-cost NDIR carbon dioxide sensor. The Fabry-Perot filter consists of upper and lower DBR pairs, which comprise multilayered stacks of alternating high- and low-index thin films, and a cavity layer for the resonance of incident light. As the number of DBR pairs inside the reflector increases, the FWHM of the transmitted light becomes narrower, but the transmittance of light decreases substantially. Therefore, it is essential to analyze the relationship between the FWHM and transmittance according to the number of DBR pairs. The DBR is made of silicon and silicon dioxide by RF magnetron sputtering on a glass wafer. After the optimal conditions based on simulation results were realized, the DBR exhibited a light transmittance of 38.5% at 4.26 ㎛ and an FWHM of 158 nm. The improved results substantiate the advantages of the low-cost and minimized process compared to expensive commercial filters.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.6
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• pp.84-92
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• 2013

This study improves the formability in fine-blanking the lock plate of car seat belts using a low carbon steel(SM35C) plate. The optimal die design for the forming process is proposed using rules for process planning based on theories and field experiences. The optimal design is analyzed using commercial finite element software in order to solve the fracture problems in the extrusion process. Through the improved layout based on the FEM results, the fracture of the extruded part and the roll over problem are solved. Furthermore, it is demonstrated through the shown from experiments that the extruded part does not break in the modified die.

• Structural Engineering and Mechanics
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• v.71 no.3
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• pp.283-290
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• 2019

In global competition manufacturing companies have to produce modern, new constructions from advanced materials in order to increase competitiveness. The aim of my research was to develop a new composite cellular plate structure, which can be primarily used for structural elements of road, rail, water and air transport vehicles (e.g. vehicle bodies, ship floors). The new structure is novel and innovative, because all materials of the components of the newly developed structure are composites (laminated Carbon Fiber Reinforced Plastic (CFRP) deck plates with pultruded Glass Fiber Reinforced Plastic (GFRP) stiffeners), furthermore combines the characteristics of sandwich and cellular plate structures. The material of the structure is much more advantageous than traditional steel materials, due mainly to its low density, resulting in weight savings, causing lower fuel consumption and less environmental damage. In the study the optimal construction of a given geometry of a structural element of a road truck trailer body was defined by single- and multi-objective optimization (minimal cost and weight). During the single-objective optimization the Flexible Tolerance Optimization method, while during the multi-objective optimization the Particle Swarm Optimization method were used. Seven design constraints were considered: maximum deflection of the structure, buckling of the composite plates, buckling of the stiffeners, stress in the composite plates, stress in the stiffeners, eigenfrequency of the structure, size constraint for design variables. It was confirmed that the developed structure can be used principally as structural elements of transport vehicles and unit load devices (containers) and can be applied also in building construction.