• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2003.04a
• /
• pp.494-499
• /
• 2003

This paper concerns the static, dynamic and thermal characteristics analysis of a high-speed spindle system for horizontal machining centers with 45mm x50,000rpm. The spindle system is designed based on the angular contact ceramic ball bearings, built-in motor, oil-air lubrication method and oil jacket cooling method. The structural and thermal analysis models of spindle system are constructed by the finite element method. The static and dynamic characteristics are estimated based on the static deformation, modal parameter, mode shape and frequency response function, and the thermal characteristics are estimated based on the temperature rise, temperature distribution and thermal deformation. The analysis results illustrate that the designed spindle system has excellent structural and thermal stabilities

• 한국방재학회:학술대회논문집
• /
• 2008.02a
• /
• pp.711-714
• /
• 2008

The objective of this study is to analyze the relationship between the watershed characteristics and the critical duration of design rainfall. For estimation of critical duration, adjustment Huff's method and ILLUDAS urban runoff model were applied to urban 21 areas. Watershed characteristics such as area, channel length, channel slope, shape factor, and pipe density were used to simulate correlation analysis. The conclusions of this study are as follows; it is revealed that critical duration is influenced by the watershed characteristics such as pipe density, area and channel length. Also, multiple regression analysis using watershed characteristics is carried out and the determination coefficient of multiple regression equation shows 0.972.

• Journal of the military operations research society of Korea
• /
• v.27 no.1
• /
• pp.101-113
• /
• 2001

Taguchi and VTA(variation Transmission Analysis) methods have been widely used recently as new methods for product design. In this study, Taguchi method using analysis of variance and VTA method using regression analysis are reviewed and compared with each other in terms of parameter design and tolerance design. In analysis of variance, variation of quality characteristics arises from noise factors, therefore the optimal levels of design factors are selected to minimize the effect of noise factors. n regression analysis, variation of quality characteristics arises from variation of each own design factors. As a method to reduce variation of these quality characteristics, sensitivity analysis was performed for each design factors. An example of calculating tolerance interval for the given defect rate in PPM is also introduced. Especially, the new method is suggested to increase the estimation accuracy of variation of quality characteristics through regression analysis.

• Journal of Korean Society for Quality Management
• /
• v.25 no.2
• /
• pp.140-153
• /
• 1997

As product quality is maily determined in the product design and process design step, systematic design should be performed through parameter design and tolerance design. Therefore, we introduced analysis of variance and regression analysis as a statistical method which determine optimal levels of affective design factors to product characteristics, then we compared that process and result. In analysis of variance, variation of quality characteristics arises from noise factors, so the optimal levels of design factors are selected to minimize the effect of noise factors. In regression analysis, variation of quality characteristics aries from variation of each own design factors. As a method to reduce variation of these quality characteristics, sensitivity analysis was performed about each design factors. Through this sensitivity analysis, we represented process to calculate the interaction term of the factors.

• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.1844-1847
• /
• 1997

Assuming that EEG(electroencephalogram), which is generated by a nonlinear electrical of billions of neurons in the brain, has chaotic characteristics, it is confirmend by frequency spectrum analysis, log frequency spectrum analysis, correlation dimension analysis and Lyapunov exponents analysis. Some chaotic characteristics are related to the degree of brain activity. The slope of log frequency spectrum increases and the correlation dimension decreasess with respect to the activities, while the largest Lyapunov exponent has only a rough correlation.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.2217-2220
• /
• 2003

It is known that an EEG is characterized by the unique and personal characteristics of an individual. Little research has been done to take into account these personal characteristics when analyzing EEG signals. Often the EEG has frequency components which can describe most of the significant characteristics. These combinations are often unique like individual human beings and yet they have an underlying basic characteristics as well. We think that these combinations are the personal characteristics frequency components of the EEG. In this seminar, the EEG analysis method by using the Genetic Algorithms (GA), Factor Analysis (FA), and the Neural Networks (NN) is proposed. The GA is used for selecting the personal characteristic frequency components. The FA is used for extracting the characteristics data of the EEG. The NN is used for estimating the characteristics data of the EEG. Finally, in order to show the effectiveness of the proposed method, classifying the EEG pattern is carried out via computer simulations. The EEG pattern is evaluated under 4 conditions: listening to Rock music, Schmaltzy Japanese ballad music, Healing music, and Classical music. The results, when personal characteristics frequency components are NOT used, gave over 80 % accuracy versus a 95 % accuracy when personal characteristics frequency components are used. This result of our experiment shows the effectiveness of the proposed method.

• The Research Journal of the Costume Culture
• /
• v.23 no.2
• /
• pp.228-241
• /
• 2015

The purpose of this study was to verify the effect of mobile fashion shopping characteristics and perceived interactivity on perceived usefulness, and the effect of perceived usefulness on purchase attitude and purchase intention based on TAM (Technology Acceptance Model). We conducted the survey targeting smartphone users in their 20s~30s living in Seoul and metropolitan area. Among 483 data collected, we used 452 samples except 31 unreliable respondents for the analysis. To analyze the structural equation model, we did factor analysis, reliability analysis, and structural equation model analysis using SPSS 18.0 and AMOS 16.0. The results were as follows: We confirmed 5 mobile fashion shopping characteristics (enjoyment, credibility, instant connectivity, security, and personalization) and 3 perceived interactivity factors (control, responsiveness and two-way communication, and contextual offer) as results of confirmative factor analysis. Mobile fashion shopping characteristics and perceived interactivity had positive effects on perceived usefulness. Mobile fashion shopping characteristics affected perceived interactivity and also had indirect effect on perceived usefulness via perceived interactivity. In other words, mobile fashion shopping characteristics had direct and indirect effect on perceived usefulness. Perceived usefulness influenced purchase attitude and purchase attitude influenced purchase intention. Perceived usefulness had direct effect on purchase intention and the indirect effect through purchase attitude was significant.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.18 no.4
• /
• pp.44-50
• /
• 2010

Structural vibration is a significant problem in many multi-part or multi-component assemblies. In aircraft industry, structures are composed of various fasteners, such as bolts, snap, hinge, weld or other fastener or connector (collectively "fasteners"). Due to these, prediction and design involving dynamic characteristics is quite complicated. However, the current state of the art does not provide an analytical tool to effectively predict structure's dynamic characteristics, because consideration of structural uncertainties (i.e. material properties, geometric tolerance, dimensional tolerance, environment and so on) is difficult and very small fasteners in the structure cause a huge amount of analysis time to predict dynamic characteristics using the FEM (finite element method). In this study, to resolve the current state of the art, a new approach is proposed using the FEM and probabilistic analysis. Firstly, equivalent elements are developed using simple element (e.g. bar, beam, mass) to replace fasteners' finite element model. Developed equivalent elements enable to explain static behavior and dynamic behavior of the structure. Secondly, probabilistic analysis is applied to evaluate the PDF (probability density function) of dynamic characteristics due to tolerance, material properties and so on. MCS (Monte-Carlo simulation) is employed for this. Proposed methodology offers efficiency of dynamic analysis and reality of the field as well. Simple plates joined by fasteners are taken as an example to illustrate the proposed method.

• The Research Journal of the Costume Culture
• /
• v.7 no.1
• /
• pp.1-12
• /
• 1999

Analysis of Customer Characteristics on Environment-Friendly Clothing Products The purpose of this study is to analyze the characteristics of the environment-friendly customers in Korean fashion market. The study is analyzed through questionary paper to the domestic female group of more than or equal to age of twenty living in Seoul. The collected questionary paper is analyzed with SPSS/PC/sub +/ program and the method of statistical analysis used for this study is frequency analysis, factor analysis, cluster analysis, t-test, and crosstab analysis. The result of analysis of the characteristics of the environment -friendly customers involves the following: Firstly, there were no significant difference in the demographic characteristics between the environment-friendly customer group and non-environment-friendly customers group. Secondly, environment-friendly customers had more environmental programs, had seen and heard more environmental program through current news from TV, newspapers, and magazines, and had more interest in recycling or separated collecting of garbage, and been doing better recycling or separated collecting. These serial processes of research, have the meaning in confirming that segmented market for environment-friendly customers exists in the domestic fashion market, and these will not only set up the basis of research on the market of environment-friendly fashion product but also be able to contribute to propose future direction of research.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.9 no.4
• /
• pp.99-107
• /
• 2000

In this study, a static and dynamic characteristics analysis system for machine tool spindle systems with 3 lobe sliding bearing is developed based on Timoshenko theory, finite element method and windows programming techniques. And the characteristics value of 3 lobe sliding bearing such as eccentricity ratio, attitude angle, friction coefficient , stiffness coefficients, damping coefficients and so on, are determined by using the thermal equilibrium conditions of spindle systems. Since the developed system has various analysis modules related to static deformation analysis, modal analysis, frequency responses analysis and so on, it can be utilized to perform systematically the design an devaluation process of spindle systems with 3 lobe sliding bearing under windows GUI environment.