• KSTLE International Journal
• /
• v.1 no.1
• /
• pp.63-68
• /
• 2000

Angular contact ball bearings are mainly used in the spindle, which requires high speed and stiffness. The heat generation is studied by experiments and simulations using a pair of angular contact ball bearings. The temperature variation of inner and outer races and the temperature increment distribution are measured by using thermocouples for the rotational speed, preload, viscosity of lubricant. The measured values from experiments are used to estimate the heat conduction rate. The method of oil-air lubrication is used for the experiment. The amount of conduction heat transfer to the test spindle and the convection heat transfer coefficients long the spindle are computed by using inverse method with temperature increment distribution. Total heat generation rate is estimated with the heat partition rate which is calculated from temperatures of inner and outer races. In addition, the empirical factor of oil-air lubrication method for Palmgren's heat generation model is suggested. The empirical friction coefficients, which are obtained from the experiments, depend on the preload condition, and can give us more accurate estimation of the heat generation in ball bearings.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.8 no.1
• /
• pp.83-95
• /
• 2000

Lift, drag, pitching moment, what we call longitudinal aerodynamic coefficient, effects airplanes directly, so the method to find the accurate result quickly is an important factor from the beginning of the aircraft design. There are different ways to find aerodynamic coefficient such as empirical methods, numerical analysis methods, wind tunnel tests, and finally through an actual flight tests, but choosing the best methods depends on the due date or the cost. The accuracy varies on each design level, but all this methods have relationship to complement and balance each other, so by combining proper methods, the best result can be obtained. At this paper, empirical methods and numerical analysis method were experimented, compared, and reviewed to find the availability of each method and by combining two methods accurate result was obtained. So, we applied this methods to predict the aerodynamic coefficient on cruise configuration aircraft, and was able to obtain more accurate result on the low speed longitudinal aerodynamic coefficient. Also by watching there result, we are able to predict the errors before the actual wind tunnel test.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.5 no.4
• /
• pp.199-211
• /
• 2009

The purpose of this study is to elicit influential factors on accepting IPTV services and define the casual relationship between the factors, and "user satisfaction", "re-use intention", "stranger recommendation intention", in an attempt to provide useful guidelines to IPTV carriers, contents providers and equipment makers for their forming IPTV service models and marketing strategies. For this end, the theoretical background of this study has been brought from relevant literature, and theoretical study models have been established by logical reasoning of the interrelation among diverse components. Then, the established models have been analyzed by using statistical packages "SPSS(12.0), LISREL(8.72)". Finally theoretical and practical significance and future study direction have been suggested. To make sure of effective validity of IPTV service adoption models above, empirical studies should be made continuously. And then vertical and horizontal studies at a specific point would show ever-changing causal relationship, helping to promote financial outcome of relevant companies and organizations.

• Bulletin of the Korean Chemical Society
• /
• v.24 no.9
• /
• pp.1265-1268
• /
• 2003

The estimation of retention factors by correlation equations with physico-chmical properties maybe helpful in chromatographic work. The physico-chemical properties were water solubility (S), hydrophobicity (P), total energy ($E_t$), connectivity index 1 ($^1{\chi}$), hydrophilic-lipophlic balance (x) and hydrophilic surface area (h) of isoflavones. The retention factors were experimentally measured by RP-HPLC. Especially, the empirical regulations of water solubility and hydrophobicity were expressed in a linear form. The equation between retention factors and various physico-chemical properties of isoflavones was suggested as $k = a_0 + a_1\;log S + a_2log\;P^Q + a_3(E_t) + a_4(^1{\chi}) + a_5(x) + a_6(h)$, and the correlation coefficients estimated were relatively higher than 0.95. The empirical equations might be successfully used for a prediction of the various chromatographic characteristics of substances, with a similar chemical structure.

• Journal of the Korean Data and Information Science Society
• /
• v.19 no.4
• /
• pp.1081-1089
• /
• 2008

Beginning in the 2007-2008 season, the men's pro-basketball league changed a foreigner selection method by introducing a draft system which leads to a tryout from the free agency system. Also in the same season, the woman's pro-basketball league changed its system from one that permitted foreign players to one that doesn't allow foreign player participation. The reason for this change is thought to be financial problems. However this institutional change brings about the reduction in the quality of basketball and it will affect spectators in a negative way. The empirical study attempted to analyze the effects which follows an institutional change in Korean men's pro-basketball. The research showed that the men's pro-basketball league wasn't affected at all due to foreigner selection method by a draft system that led to a tryout from the free agency system.

• Journal of Digital Convergence
• /
• v.2 no.1
• /
• pp.113-126
• /
• 2004

In this paper we would like to provide a help to implementing KMS(Knowledge Management System) in public sector. For this purpose, we set up five contingency environmental factors and three process factors of knowledge management. And then investigates affecting factors effect on the performance of KMS in public sector by empirical study, A field survey of public officers in Korea local government was conducted. Complete data for 333 KMS users was analyzed to determine relationship of the research constructs. The system of evaluation and compensation is the most important factor effects on the process of KM and the performance of KMS. These results provide empirical evidence that supports the necessity of rational motivation systems does lead to effective implementation of KMS in public sector.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.864-869
• /
• 2004

In this paper, a blackbox approach is carried out to model the nonlinear dynamic bushing model. One-axis durability test is performed to describe the mechanical behavior of typical vehicle elastomeric components. The results of the tests are used to develop an empirical bushing model with an artificial neural network. The back propagation algorithm is used to obtain the weighting factor of the neural network. Since the output for a dynamic system depends on the histories of inputs and outputs, Narendra's algorithm of 'NARMAX' form is employed in the neural network bushing module. A numerical example is carried out to verify the developed bushing model.

• International Commerce and Information Review
• /
• v.6 no.1
• /
• pp.77-98
• /
• 2004

This paper examines the major determinants affecting the user satisfaction on e-Trade portal sites in small and medium-sized exporters. The development of our research model is based on the empirical studies on the service quality of information system, web sites or Internet shopping mall, and on the factors influencing the user satisfaction. With the help of a regression analysis and factor analysis, five hypotheses are derived and tested. The results from regression analysis suggest that the user satisfaction of e-Trade portal sites is affected by information characteristics and ease of use of e-Trade portal sites. In addition, the user satisfaction of e-Trade portal sites is enhanced by support for international trade. Our findings will be useful, especially for those who are planning to build user-oriented e-Trade portal sites.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.11 no.4
• /
• pp.151-157
• /
• 2003

In this paper, a blackbox approach is carried out to model the nonlinear dynamic bushing model. One-axis durability test is performed to describe the mechanical behavior of typical vehicle elastomeric components. The results of the tests are used to develop an empirical bushing model with an artificial neural network. The back propagation algorithm is used to obtain the weighting factor of the neural network. Since the output for a dynamic system depends on the histories of inputs and outputs, Narendra algorithm of 'NARMAX' form is employed to consider these effects. A numerical example is carried out to verify the developed bushing model.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.8 no.3
• /
• pp.754-760
• /
• 2004

The purpose of this paper is to examine the empirical analysis for charging factors and the evaluation models of internet site. Thus this is to analyze the charging factors affecting the consumer satisfaction of health information sites in the Internet. Based on the covariance structural model applied to a customer survey, this study shows that among the characteristics of the site, contents has the most significant effect on charging factor and customer satisfaction, which in turn affects the consumer willingness to recommend the site to others.