• Korean Journal of Computational Design and Engineering
• /
• v.3 no.4
• /
• pp.211-222
• /
• 1998

Parametric design is an important modeling paradigm in CAD/CAM applications, enabling efficient design modifications and variations. One of the major issues in parametric design is to develop a geometric constraint solver that can handle a large set of geometric configurations efficiently and robustly. In this appear, we propose a new approach to geometric constraint solving that employs a graph-based method to solve the ruler-and-compass constructible configurations and a numerical method to solve the ruler-and-compass non-constructible configurations, in a way that combines the advantages of both methods. The geometric constraint solving process consists of two phases: 1) planning phase and 2) execution phase. In the planning phase, a sequence of construction steps is generated by clustering the constrained geometric entities and reducing the constraint graph in sequence. in the execution phase, each construction step is evaluated to determine the geometric entities, using both approaches. By combining the advantages of the graph-based constructive approach with the universality of the numerical approach, the proposed approach can maximize the efficiency, robustness, and extensibility of geometric constraint solver.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.8
• /
• pp.1466-1470
• /
• 2007

MEMS design flow based on DFM concept is presented and applied to gyroscope design as a test case. It is purposed to contribute to the yield improvement by considering the process-related parameters from the design phase. After defining the performance requirements, the sensitivity analysis should be done on the draft design(s) to find out the key parameters related with the device performance. By doing so, TEG can be designed for the selected process and/or material parameters. Through a set of test runs, the process capability is characterized and the material properties are extracted using the TEG. Then we can estimate the virtual yield of the current process for the designed device by running Monte Carlo analysis where the process and/or material property variations are considered. The estimated yield will make us redesign the device to be more robust or improve the current process to have the smaller variations.

• Journal of Korean Association for Spatial Structures
• /
• v.13 no.2
• /
• pp.47-55
• /
• 2013

The design composition elements and the mechanical behavior of trusses have been investigated for Pratt trusses. As a result, it was determined that the design composition elements of the trusses consist of the composition of webs, the distance between joints, the chords profile, the depth of the truss, and the double chord composition. In addition, by analyzing models with a variation of elements, comprehensive features of structural behavior have been presented for variations of design of Pratt trusses. This is to provide more effective and useful design information on truss structure in the architectural and structural planning stage.

• Journal of the Korea Fashion and Costume Design Association
• /
• v.17 no.3
• /
• pp.61-71
• /
• 2015

In this study, visual evaluation was performed with changes in peplums design to provide data which can enhance wearing image effects at the production of peplums one-piece. According to changes in volume and position of peplums, a total of 9 stimulants were chosen. Then, they were evaluated using a seven-point rating scale against 50 fashion students. The data has been analyzed by Factor Analysis, ANOVA, $Scheff{\acute{e}}$'s Test and the MCA method. The results of the study are as follows : 1. According to factor analysis, the components of visual evaluation depending on the changes in volume and position variations of peplums were divided into four factors: elegance, individuality, upper body correction and upper body emphasis. 2. According to visual evaluation depending on changes in the position variations of peplum, 'high waist' and 'natural waist' revealed a significant difference in elegance, individuality and upper body correction. 'Low waist' was observed in all four positions. 3. According to visual evaluation depending on the changes in volume of peplums, a significant difference at $45^{\circ}$ was observed in except for elegance. Significant differences at $90^{\circ}$ and $180^{\circ}$ were observed in all four positions. 4. In terms of interactions over in volume and position variations of peplums, interaction effects were found in two factors.

• The Bulletin of The Korean Astronomical Society
• /
• v.44 no.1
• /
• pp.43.2-43.2
• /
• 2019

In many astrophysical systems, smooth large-scale variations coexist with small-scale fluctuations. For example, a large-scale velocity or density gradient can exist in molecular clouds that have small-scale fluctuations by turbulence. In redshifted 21cm observations, we also have two types of signals - the Galactic foreground emissions that change smoothly and the redshifted 21cm signals that fluctuate fast in frequency space. In many cases, the large-scale variations make it difficult to extract information on small-scale fluctuations. We propose a simple technique to remove smooth large-scale variations. Our technique relies on multi-point structure functions and can obtain the magnitudes of small-scale fluctuations. It can also be used to design filters that can remove large-scale variations and retrieve small-scale data. We discuss how to apply our technique to irregularly spaced data, such as rotation measure observations toward extragalactic radio point sources.

• Proceedings of the KIEE Conference
• /
• 2004.10a
• /
• pp.182-184
• /
• 2004

This paper presents a PI controller tuning method for high performance permanent magnet synchronous motor (PMSM) drives under load variations using clustering fuzzy algorithm. In many speed tracking control systems PI controller has been used due to its simple structure and easy of design. PI controller, however, suffers from the electrical machine parameter variations and disturbances. In order to improve the tracking control performance under load variations, the PI controller parameters are modified during operation by clustering fuzzy method. This method based on optimal fuzzy logic system has simple structure and computational simplicity. It needs only sample data which is obtained by optimal controller off-line. As the sample data implemented in the adaptive fuzzy system can be modified or extended, a flexible control system can be obtained Simulation results show the usefulness of the proposed controller.

• Korean Journal of Optics and Photonics
• /
• v.27 no.1
• /
• pp.32-40
• /
• 2016

The characteristics of an optical system vary depending on wavelength and ambient temperature. Based on the thin-lens approximation, we investigate the conditions for stabilizing an optical system against wavelength and temperature variations at the same time. The conditions are applied to designing a laser scanning system consisting of two lenses. The change in the effective focal length of the scanning system against wavelength and temperature variations is very small, as expected.

• Journal of international Conference on Electrical Machines and Systems
• /
• v.2 no.3
• /
• pp.342-348
• /
• 2013

As a number of wind power generation systems have been installed in power systems in the world, frequency fluctuations due to output power variations from wind farms have become a serious problem. Battery systems have been studied for smoothing the output variations and decreasing the resulting frequency fluctuations. Among these studies, efficient design of battery systems is one of the most important subjects from a point of view of cost. This paper presents a comparative analysis of the smoothing effect between the conventional moving average method and a new method based on frequency response analysis.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.11
• /
• pp.2655-2663
• /
• 1993

In order to evaluate the relative significance of tolerance management of various elements in a VHS VTR tape transport system, the effect of geometric variations of the elements from standard design values on the tape traveling path is studied. The tape is modeled as a string and each element in the tape transport system is modeled as a cylinder whose radius, position vector and orientation vector are specified. An numerical algorithm is proposed to find the coordinates of tape entry points and tape exit points for the elements from which the tape traveling path can be completely described. By using the suggested algorithm, an error sensitivity analysis of tape traveling path due to the geometric variations of tape transport elements is performed for a particular model in the market and the elements demanding relatively strict tolerance management are identified.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.14 no.1
• /
• pp.44-50
• /
• 2015

This paper presents a heuristic process-optimization procedure for minimizing warpage in injection-molded parts based on the dynamic robust design methodology. The injection molding process is known to have intrinsic variations of its process conditions due to various factors, including incomplete process control facilities. The aim of the robust design methodology advocated by Taguchi is to determine the optimum design variables in a system which is robust to variations in uncontrollable factors. The proposed procedure can determine the optimal robust conditions of injection molding processes at a minimum cost through a trade-off strategy between the degree of warpage and the packing time.