• Journal of the Korea Computer Industry Society
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• v.2 no.2
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• pp.165-180
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• 2001

This study is on the design and performance evaluation of a multi medium access control(MAC) protocol for multimedia access in the wireless ATM network. In general, MAC protocols for multimedia data transmission are classified into the fixed slot allocation algorithm that allocates base-station slots equally over terminals, and the dynamic slot allocation algorithm that with flexible penetration. The conventional slot allocation algorithms assign slots based on the average bandwidths required for various services types. Although the algorithms have a wide bandwidth for real-time-variant services, the slots are being wasted due the service types. To improve the slot waste problem, this thesis proposes a method that minimizes the waste by assigning variable slots based on the most appropriate bandwidth after a base-station analyzes the service type requested from terminals.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.524-526
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• 1999

In the construction of successful fuzzy models and/or controllers for nonlinear systems, the identification of a good fuzzy inference system is an important yet difficult problem, which is traditionally accomplished by a time-consuming trial-and-error process. In this paper, we propose a systematic identification procedure for complex multi-input single-output nonlinear systems with DNA coding method. A DNA coding method is optimization algorithm based on biological DNA as conventional genetic algorithms(GAs) are. The strings in the DNA coding method are variable-length strings, while standard GAs work with a fixed-length coding scheme. the DNA coding method is well suited to learning because it allows a flexible representation of a fuzzy inference system. We also propose a new coding method fur applying the DNA coding method to the identification of fuzzy models. This coding scheme can effectively represent the zero-order Takagi-Sugeno(TS) fuzzy model. To acquire optimal TS fuzzy model with higher accuracy and economical size, we use the DNA coding method to optimize the parameters and the number of fuzzy inference system. In order to demonstrate the superiority and efficiency of the proposed scheme, we finally show its application to a Duffing-forced oscillation system.

• The Journal of Information Systems
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• v.20 no.2
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• pp.81-107
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• 2011

Group features such as group cohesion and consistency on appropriation(COA), which have been constructed through social interactions, should be noted for characterizing online game, especially, clan based massively multi-players online game (MMOG). This study attempted to identify the relationship between group characteristics and users' effectiveness of MMOG considering group experience. For this purpose, a research model was suggested: group cohesion and COA are variables for explaining group features, perceived use control is a variable for individual competency of playing MMOG, and perceived winning and perceived enjoyment are dependent variables. Moreover, group experience was included as a moderating variables for two relationships, group cohesion-preceived winning and COA-perceived winning. For the validation of this research model, 100 users for Sudden Attack which is one of very well known MMOG games were surveyed by questionnaires. Before survey, they were grouped into 10 teams and were played over ten times by team for perceiving group consciousness. In result, most hypotheses were statistically supported except the relationship between group cohesion and perceived winning.

• Journal of the Ergonomics Society of Korea
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• v.17 no.1
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• pp.91-102
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• 1998

History of the Sensibility Ergonomics is explained. Concepts, definition, and research methods on the human sensibility are proposed for systematic applications of human sensibility studies to product and environment developments. Sensibility Ergonomics was born in socio-technological environments where consumers required aesthetic and satisfactory products in addition to useful and usable ones, and manufactures were trying to develop consumer-oriented, user-friendly products. Sensibility Ergonomics is defined as "multi-disciplinary and inter-disciplinary processes for developing products and environment as usable, comfortable and satisfactory with the information on human sensibility." Human sensibility is functionally defined as "feelings generated when perceived sensory and information stimuli are reflected from memory which has been accumulated through personal experiences." Human sensibility is affected by at least three factors: personal, social, and cultural. Consumers evaluate products in three aspects : functional, sensorial, and cultural sensibilities. Human sensibility is personal, dynamic, and ambiguous. It is generated reflectively and intuitively against external stimuli. No Physiological responses are accompanied, and one cannot control his/her sensibility. However, the sensibility affects the decision making or behavior of the person. To understand the human sensibility many inter-disciplinary methods should be used instead of one-variable approach. Micro-scopic studies such as Questionnaire, interview, behavioral analysis, and psychophysiological experiments can be performed. In addition, social and cultural studies are essential to understand an individual's sensibility. Results of sensibility studies can be applied to setup new interactions between human and machine through sensible(or affective) human-machine (computer) interfaces. Human-oriented and user-friendly products can be made with the information on human sensibility.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.3 s.234
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• pp.418-424
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• 2005

We present the design, fabrication and experimental results of 4-bit digital microinjectors, whose ejected droplet volumes are adjusted by the digital operation of a 4-bit microheater array. We design the reference microinjectors as well as its comparative test structures. In the fabrication process, we use a five-mask micromachining process and the total chip size of the fabricated microinjector is $7,640{\mu}m{\times}5,260{\mu}m.$ We measure the ejected droplet volumes and velocities, which are adjusted from $12.1{\pm}1.0~55.6{\pm}14.7pl\;and\;2.3{\pm}0.1~15.7{\pm}0.8m/s.$ respectively, depending on the 15 possible combinations of 4-bit microheater array. We also experimentally characterize the effect of geometric variation including the microheater size, inter-microheater gap, microchannel width and sequential operation of microheater array on the ejected droplet volume and velocity. Among these parameters, we find that the microheater size is the most dominant parameter affected to the ejected droplet volumes and velocities. Thus, the present microinjector has a potential for application to the high-resolution inkjet printers with multiple gray levels or high-precision fluid injectors with variable volume control.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.2 s.191
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• pp.110-117
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• 2007

In this paper, probabilistic distribution of chassis component fatigue life is determined statistically by applying the design of experiments and the Pearson system. To construct p - ${\varepsilon}$ - N curve, the case that fatigue data are random variables is attempted. Probabilistic density function (p.d.f) for fatigue life is obtained by the design of experiment and using this p.d.f fatigue reliability, any aimed fatigue life can be calculated. Lower control arm and rear torsion bar of chassis components are selected as examples for analysis. Component load histories which are obtained by multi-body dynamic simulation for Belsian load history are used. Finite element analysis is performed by using commercial software MSC Nastran and fatigue analysis is performed by using FE Fatigue. When strain-life curve itself is random variable, the probability density function of fatigue life has very little difference from log-normal distribution. And the cases of fatigue data are random variables, probability density functions are approximated to Beta distribution. Each p.d.f is verified by Monte-Carlo simulation.

• Journal of Distribution Science
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• v.14 no.12
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• pp.53-59
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• 2016

Purpose - The concept of lifetime job has disappeared, and men are interested in business foundation to work continuously with similar jobs. The value of business foundation is thought to be important in accordance with the viewpoint of society, government, individuals and family. Research design, data, and methodology - The economic exchange between South Korea and China has been expanded, and they are likely to play an important role in entry into China by business foundation in accordance with economic exchange between the two countries. As Korean residents inflow overseas, small businessmen business foundation shall be given attention scientifically and Korean Chinese business foundation shall be given attention as well. Results - The study investigated the effects on psychological characteristics and small business foundation motives upon business foundation will by using models. Self-efficacy and self achievement had positive influence upon small business foundation of Korean Chinese. The use of control variable had explanatory power (29.6%). Conclusions - The findings would help the government's small business foundation system to promote small business foundation and to be a guide for expansion in Korean Chinese's small business markets. An education program should be developed to strengthen Korean Chinese's self efficacy considering psychological characteristics.

• Journal of Korean Society for Atmospheric Environment
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• v.10 no.4
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• pp.224-232
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• 1994

A new neural network model has been developed to predict short-term air pollution concentration. In addition, a multiple regression model widely used in statistical analysis was tested. These models were applied for prediction of daily maximum ozone concentration in Seoul during the summer season of 1991. The time periods between May and September 1989 and 1990 were utilized to train set of learning patterns in neural network model, and to estimate multiple regression model. To evaluate the results of the different models, several Performance indices were used. The results indicated that the multiple regression model tended to underpredict the daily maximum ozone concentration with small r$^{2}$(0.38). Also, large errors were found in this model; 21.1 ppb for RMSE, 0.324 for NMSE, and -0.164 for MRE. On the other hand, the results obtained from the neural network model were very promising. Thus, we can know that this model has a prominent efficiency in the adaptive control for the non-linear multi- variable systems such as photochemical oxidants. Also, when the recent new information was added in the neural network model, prediction accuracy was increased. From the new model, the values of RMSE, NMSE and r$^{2}$ were 13.2ppb, 0.089, 0.003 and 0.55 respectively.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.5
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• pp.670-677
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• 1999

An analysis of generation and growth of multicomponent particles has been carried out to predict the size and composition distributions of particles generated in the Modified Chemical Vapor Deposition(MCVD) process. In MCVD process. scale-up of sintering and micro-control of refractive index may need the Information about the size and composition distributions of $SiO_2-GeO_2$ particles that are generated and deposited. The present work solved coupled steady equations (axi-symmetric two dimensions) for mass conservation, momentum balance. energy and species(such as $SiCl_4$, $GeCl_4$, $O_2$, $Cl_2$) conservations describing fluid flow. heat and mass transfer in a tube. Sectional method has been applied to obtain multi-modal distributions of multicomponent aerosols which vary in both radial and axial directions. Chemical reactions of $SiCl_4$ and $GeCl_4$ were included and the effects of variable properties have also been considered.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.601-603
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• 2013

The nodes of Ad-hoc network are made up of location registration for sending informations and a great number of packet transmissions to maintain routing route among the nodes. Under this environment, a huge number of traffics would be generated as mobility variable occurs more than in physical network. Hence, in this paper, focused on to study the relationship of nodes to analyze the extent of the traffic in order to control the traffics of the multi-hop in Ad-hoc.