• Journal of Hydrogen and New Energy
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• v.35 no.1
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• pp.75-82
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• 2024

In this study, design parameter exploration based on finite element analysis was performed to find the optimal shape of bellows, the key component of compressor-embedded refueling tank for a newly developed hydrogen refueling station capable of high-pressure charging above 900 bar. In the design parametric study, the design variables took into account the bellows shapes such as contour radius and span spacing, and the response factors were set to the maximum stress and the gap in the contact direction. In the shape design of the compressor bellows for hydrogen refueling station considered in this study, it was found that adjusting the contour span is an appropriate design method to improve the compression performance and structural safety. From the selection of optimal design, the maximum stress was reduced to 49% compared to the initial design without exceeding the material yield stress.

• Journal of Korean Association for Spatial Structures
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• v.7 no.3 s.25
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• pp.57-66
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• 2007

The membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The material property of the membrane has strong axial stiffness, but little bending stiffness. The design procedure of membrane structures are needed to do shape finding, stress-deformation analysis and cutting pattern generation. In shape finding, membrane structures are unstable structures initially. These soft structures need to be introduced initial stresses because of its initial unstable state, and happen large deformation phenomenon. Therefore, in this paper, we investigate the convergence of solution and the speed according to the control variables and the method of shape analysis.

• Journal of the Korean Institute of Landscape Architecture
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• v.27 no.3
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• pp.58-68
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• 1999

Purpose of this thesis is to find out the relationship among the amount of change and the visual cognition, and the visual preference which people like and can feel. Through the investigation of relationships between the amount of change, which indicates the degree of visual variation and the visual preference, the amount of change and the visual cognition, and the visual preference and the visual cognition, basic design data will be supplied, which can satisfy users' desire as much as possible in the most economic way. In order to investigate the relationship between the visually produced the amount of change and preferences, graphic simulation, in which variables other than the visual change are controlled, has been proceeded. Graphic factors of the visual change in the cyber exterior space are determined on the point of location (base plane, vertical plane, overhead plane), shape, size and color. As for the relationship between the amount of change and the preference, only the size is effective. since preferences on the location, shape and color are individual preferences, no common trend can be found. Therefore, we cannot say that which shape or color is better, Since the location, shape and color are qualitative change and the size is the quantitative change, the size can be the measurable change quantity. The relationship between the amount of change of size and the degree of preference is found to be inverse U-shape, i.e., as the amount of change of size increases the degree of preference first increases and, after a certain level, decreases. The same result has been obtained in photo simulation.

• Tunnel and Underground Space
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• v.8 no.4
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• pp.332-341
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• 1998

Conventional polishing of stone panel edges has been done by hand. While this has changed somewhat with the advent of automatic machines, it is still very much a hand finishing technology. For the development of edge shape milling tool, the primary test on characteristics of edge shape milling tool was carried out. This paper presents the results of tests focused upon the milling capability that was varied by the variables of operation parameters. Author tried to confirm the effect of six operation parameters of equipment such as rotation speed, advance speed, applied load, water flow rate and rotational direction. The result from test was described in term of shape milling capability that was defined as cutting volume of rock by unit weight of tool wear. The variance of the results could indicate the optimum level of each operating parameters. The test was also carried out to determine the abrasion resistance varied according to the abrasive flow rate. The abrasion resistance was increased with the abrasive flow rate, but over some rate it was not changed.

• Journal of ILASS-Korea
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• v.23 no.4
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• pp.192-204
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• 2018

In this study, a 3D CFD analysis method for the combustion process was established for a low calorific value syngas-diesel dual-fuel engine operating under very lean fuel-air mixture condition. Also, the accuracy of computational analysis was evaluated by comparing the experimental results with the computed ones. To simulate the combustion for the dual-fuel engine, a new dual-fuel chemical kinetics set was used that was constituted by merging two verified chemical kinetic sets: n-heptane (173 species) for diesel and Gri-mech 3.0 (53 species) for syngas. For dual-fuel mode operations, the early stage of combustion was dominated by the fuel burning inside or near the spray plume. After which, the flame propagated into the syngas in the piston bowl and then proceeded toward the syngas in the squish zone. With the baseline injection system and piston shape, a significant amount of unburned syngas was discharged. To solve this problem, effects of the injection parameters and piston shape on combustion characteristics were analyzed by calculation. The change in injection variables toward increasing the spray plume volume or the penetration length were effective to cause fast burning in the vicinity of TDC by widening the spatial distribution of diesel acting as a seed of auto-ignition. As a result, the unburned syngas fraction was reduced. Changing the piston shape with the shallow depth of the piston bowl and 20% squish area ratio had a significant effect on the combustion pattern and lessened the unburned syngas fraction by half.

• Journal of Aerospace System Engineering
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• v.13 no.1
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• pp.29-37
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• 2019

The objective of this study was to investigate the influence of the blade shape on the impeller performance, for design optimizing of the high airflow impeller. First, the quantity, angle, and length of blades, which are considered to have a large influence on the impeller performance, were selected as design variables. Then, 27 cases of impeller shapes were selected according to the design of experiment (DOE). To predict the conduct of the blower based on the selected impeller shape, flow analysis was performed using the immersed solid method of ANSYS CFX. In the CFD results, the highest airflow was expected in the impeller having a combination of 50 EA, $6^{\circ}$ and 5 mm. Finally, a blower with the original impeller shape and the optimized impeller shape was fabricated using a 3D printer, and the analysis tendency and experimental tendency were verified through experiments.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.2_2
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• pp.327-332
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• 2023

As interest in eco-friendly and fuel-efficient electric vehicles has increased globally, there has also been a growing interest in the efficiency, vibration, and noise of motors for electric vehicles Electric vehicles generally have significantly lower driving ranges per charge compared to the maximum driving range per fueling of internal combustion engine vehicles. Additionally, there are issues with various vibrations and noise generated by the motor that can cause discomfort for passengers. Therefore, research is necessary to reduce losses, vibration, and noise of the motor to improve the driving range of electric vehicles. IPMSM with a purchased design can obtain additional reluctance torque by utilizing the difference in inductance between the d and q axes. However, due to this reluctance torque, torque ripple occurs larger than other motors. The increase in torque ripple also increases noise and vibration. Since the reluctance torque, which is the main cause of torque ripple, is determined by the shape of the motor components, torque ripple can be reduced through shape optimization. In this paper, a rotor shape for reducing torque ripple and core loss that causes vibration, noise, and efficiency to decrease of IPMSM for electric vehicles was proposed. Optimization design was carried out by changing the shape of the q-axis path of the rotor to reduce the difference in inductance of the d and q-axis of the rotor. Finally, in order to verify the validity of the design variables derived through the optimal design, the original model and the improved model were compared through the FEM. Compared to the original model, the improved model's torque verifying ripple was reduced by about 62% and core loss was reduced by about 29%, the superiority of the improved model.

• Journal of the Korean Society of Clothing and Textiles
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• v.48 no.3
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• pp.563-575
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• 2024

This study analyzed 2D bodice sloper changes according to combinations of the lateral neck and shoulder points of a 3D mannequin's shoulder lines. The relationship between the 3D shape and 2D pattern was analyzed. The shoulder line was set to a default of 1cm in front of or behind the lateral neck point, 1cm in front or behind the lateral shoulder point and 1cm vertically above the lateral neck or shoulder point. When the lateral neck point was moved backward, the front neck depth, front and back shoulder height, and shoulder length in the 3D shape increased, whereas the back neck's depth and width decreased. In the 2D pattern, the back shoulder height decreased. As the lateral shoulder point moved backward, all items of the 3D shape showed little change. However, the front shoulder height for the 2D pattern decreased. Consequently, the back shoulder height increased, and the lateral neck point was raised vertically by 1cm. Meanwhile, only the back neck depth and shoulder length decreased while all other items increased; however, in the 2D pattern, the front neck width and shoulder line showed no notable change. The shoulder point was raised vertically by 1cm, and the front and back shoulder heights of the 3D shape and 2D pattern were decreased.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.357-360
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• 2007

The profile ring rolling process of Ti-6Al-4V alloy was designed by finite element(FE) simulation and experimental analysis. The design includes geometry design and optimization of process variables. The geometry design such as initial billet and blank sizes, and final rolled ring shape was carried out with the calculation method based on the uniform deformation concept between the wall thickness and ring height. FEM simulation was used to calculate the state variables such as strain, strain rate and temperature and to predict the formation of forming defects during ring rolling process. Finally, the mechanical properties of profiled Ti-6Al-4V alloy ring product were analyzed with the evolution of microstructures during the ring rolling process.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2414-2419
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• 2007

A rectangular fin with variable fin height, fin length and surrounding temperature is analyzed using a one-dimensional analytical method. Both the heat loss from a rectangular fin with non-insulated fin tip and that with insulated fin tip are presented as a function of the fin height, fin tip length and the convection characteristic number. The relative error in the heat loss of these two cases is also given as a function of the same variables. One of the results shows that the trend of heat loss for both cases with the variation of given variables is similar even though the relative error increases as the shape of the fin becomes shorter and fatter.