• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.11
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• pp.2922-2931
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• 1994

We propose a modified 6-node element, where the sampling point of Gauss quadrature moved in the thickness direction. The modified 6-node element has been applied to static problems and forced motion analyses. In this study, this method is extended to the finite element analysis of the natural frequencies of two dimensional problems. We also propose a modified 16-node element for three dimensional problems, which behaves much like a 20-node element with smaller degree of freedom. The modified 6-node and 16-node elements have been applied to the modal analyses of beams and plates, respectively. The results agree well with the results of the 8-node or 20-node element models.

• Journal of Power Electronics
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• v.13 no.4
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• pp.712-718
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• 2013

This paper proposes a control method for reducing the total harmonic distortion (THD) of the grid current of three-phase grid-connected inverter systems when the grid voltage is distorted. The THD of the grid current caused by grid voltage harmonics is derived by considering the phase delay and magnitude attenuation due to the hardware low-pass filter (LPF). The Cauchy-Schwarz inequality theory is used in order to search more easily for the minimum point of the THD. Both the gain and angle of the compensation voltage at the minimum point of the THD of the grid current are derived with the variation of cut-off frequencies of the hardware LPF. Simulation and experimental results show the validity of the proposed control methods.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.316-317
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• 2018

This paper propse the DC link capacitor voltage balancing control for three level neutral point clamped converter with harmonic component injection method. The injcetion voltage consists of harmonic component and DC link capacitor voltage difference. Theoretical analysis is provided to balance the DC link voltage, and it shows that harmonic component compensates the unbalanced condition between the capacitors. Both simulations and experiments are carried out to show that the voltage unbalance have been decreased by the proposed method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.896-897
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• 2014

Multi-lane detection is useful for the smart navigation system. In this paper, a novel multi-lane detection method is presented. The proposed three point Laplacian filter (TPLF) can complement the weak points of the previous box filter and step filter. The experimental results validate the feasibility of the proposed multi-lane detection method.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.3 s.192
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• pp.117-123
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• 2007

This paper describes a three-probe system that can be used to measure the parallelism and straightness of a pair of rails simultaneously. The parallelism is measured using a modified reversal method, while the straightness is measured using a sequential two-point method. The measurement algorithms were analyzed numerically using a pair of functionally defined rails to validate the three-probe system. Tests were also performed on a pair of straightedge rails with a length of 250 mm and a maximum straightness deviation of $0.05{\mu}m$, as certified by the supplier. The experimental results demonstrated that the parallelism-measurement algorithm had a cancellation effect on the probe stage motion error. They also confirmed that the proposed system could measure the slope of a pair of rails about $0.06{\mu}rad$. Therefore, by combining this technique with a sequential differential method to measure the straightness of the rails simultaneously, the surface profiles could be determined accurately and eliminate the stage error. The measured straightness deviation of each straight edge was less than $0.05{\mu}m$, consistent with the certified value.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2001.05a
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• pp.15-19
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• 2001

This paper describes effectiveness and characteristics of 3 P(point) task analysis as a new Ergonomic and Kansei design method for extracting user demand especially. The key point in 3 P task analysis is to describe the flow of tasks and extract any problems in each task. A solution of a problem means a user demand. 3 P task analysis cal eliminate an oversight of check items by examining the users' information processing level. The suers' information processing level was divided into the following three stages for problem extraction: acquirement of information ---> understanding and judgment ---> operation. Three stages has fourteenth cues such as difficulty of seeing, no emphasis, mapping for extracting problems. To link analysis results to the formulation of a product concept. I added a column on the right side of the table for writing the requirements (user demand) to resolve the problems extracted from each task. The requirements are extracted by using seventh cues. Finally 3 P task analysis was compared with group interview to make the characteristics of 3 P task analysis, especially extracting user demand, clear.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7855-7862
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• 2015

Cadastral map information is created by registering parcel information such as location, lot number, land category and boundary through the cadastral survey. However, with regard to boundary point coordinate, computerized cadastral information data was registered to either two decimal places (unit in centimeter) or three decimal places (unit in millimeter) so that a confusion in cadastral administration and cadastral survey has been caused. Therefore, the purpose of this study is to look for a method of matching two different coordinate systems through the consideration of registration of cadastral information data and area calculation. In conclusion, the result of the investigation not only shows that areal change and the creation of minute polygons resulted from land alteration could be solved by changing boundary point coordinate from two decimal places to three decimal places, but also suggests that the related laws and regulations to register boundary point coordinate to three decimal places should be institutionally corrected and applied.

• Korean Journal of Computational Design and Engineering
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• v.1 no.1
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• pp.65-75
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• 1996

This paper describes an automatic finite element(FE) mesh generation for three-dimensional structures consisting of free-form surfaces. This mesh generation process consists of three subprocesses: (a) definition of geometric model, i.e. analysis model, (b) generation of nodes, and (c) generation of elements. One of commercial solid modelers is employed for three-dimensional solid and shell structures. Node is generated if its distance from existing node points is similar to the node spacing function at the point. The node spacing function is well controlled by the fuzzy knowledge processing. The Delaunay method is introduced as a basic tool for element generation. Automatic generation of FE meshes for three-dimensional solid and shell structures holds great benefits for analyses. Practical performances of the present system are demonstrated through several mesh generations for three-dimensional complex geometry.

• Journal of the Korea Computer Graphics Society
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• v.29 no.3
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• pp.93-103
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• 2023

The problem of reconstructing three-dimensional models of people and objects from color and depth images captured by low-cost RGB-D cameras has long been an active research area in computer graphics. Color and depth images captured by low-cost RGB-D cameras are represented as point clouds in three-dimensional space, which correspond to discrete values in a continuous three-dimensional space and require additional surface reconstruction compared to rendering using polygonal models. In this paper, we propose an effective ray-tracing based technique for visualizing point clouds rather than polygonal models. In particular, our method shows the possibility of an effective rendering method even in mobile environment which has limited performance due to processor heat and lack of battery.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.152-155
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• 2005

A method of three-dimensional curved surface generation was studied for multi-point dieless forming (MPDF) in the shipbuilding industry. Three-dimensional coordinates of punch elements were obtained from objective surfaces using a proprietary CAD program. MPDF surfaces were generated by adjusting the height of punch elements in accordance with the coordinates. Some problems, such as collision of punch elements and contact between plates and punch bodies, were anticipated from the analysis of the results. A twisted surface was formed successfully by MPDF in a laboratory scale, which suggests possibility of application of the technology to the shipbuilding industry.