• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.6
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• pp.706-713
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• 1985

It is clear that when the amplitude of grinding chatter increases enough the contact between grinding wheel and workpiece cannot be sustained and the loss of contact occurs during a period of grinding chatter. In this paper the behavior of nonlinear grinding chatter due to the loss of contact has been studied. A nonlinear grinding chatter loop is developed where the loss of contact is considered as a nonlinear element of asymmetrical gain. The analysis is carried out in the time domain by numerical simulation and also in the complex domain by use of describing function method. The results show that two typical patterns of nonlinear grinding chatter can originate from the nonlinearity. One is an irregular chatter frequency at starting stage decreases to the natural frequency of grinding structure while the chatter amplitude increases and decreases repeatedly. The other is a limit cycle chatter of which the amplitude and frequency converge to constant and remain. This nonlinear behavior of grinding chatter has been well analyzed by the describing function method and confirmed by the numerical simulation.

• Journal of KIISE
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• v.43 no.11
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• pp.1201-1209
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• 2016

As the use of SNS continues to increase, various related studies have been conducted. According to the effectiveness of the topic model for existing theme extraction, a huge number of related research studies on topic model based analysis have been introduced. In this research, we suggested an automation system to analyze topics of each country and its distribution in twitter by combining world map visualization and issue matching method. The core system components are the following three modules; 1) collection of tweets and classification by nation, 2) extraction of topics and distribution by country based on topic model algorithm, and 3) visualization of topics and distribution based on Google geochart. In experiments with USA and UK, we could find issues of the two nations and how they changed. Based on these results, we could analyze the differences of each nation's position on ISIS problem.

• Journal of the Korean Applied Science and Technology
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• v.34 no.3
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• pp.427-435
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• 2017

To investigate whether genistein regulates menopause-induced obesity, it was studied the effects of genistein on anti-obesity effects in female ovariectomized (OVX) mice, an animal model of postmenopausal women. 7-week-old female mice (C57BL/6J) were randomly divided into three groups. All the animals received a high fat diet or a high fat diet supplemented with genistein for 8 weeks and variables and determinants of obesity were measured. The OVX mice had significantly higher body weight and adipose tissue mass than sham mice. However, genistein supplementation reduced body weight, adipose tissue mass, and adipocyte size of OVX mice. The OVX mice treated with genistein had significantly lower levels of serum triglycerides and total cholesterol than the vehicle-treated OVX mice. Lipid accumulation in liver was also markedly decreased by genistein in OVX mice. The results suggest that genistein can effectively prevent adiposity, adipocyte phertrophy, and llipid disorders caused by ovariectomy. Moreover, this study may contribute to the alleviation of metabolic syndrome, including obesity and hyerlipidemia in postmenopausal women.

• The Journal of the Korea Contents Association
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• v.9 no.1
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• pp.312-322
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• 2009

Linking between a virtual space and a physical space, ubiquitous computing is expected to create new business value. So far, however, there is no broadly accepted methodology to develop the services based on ubiquitous computing technology. Hence, this study aims to seek a systematic methodology for developing new services based on the concept of business model and to apply this in the areas of waste management practices. In addition, based on the evaluation of u-business services in waste management domain, killer services were selected, and then linked with the latest ubiquitous computing technologies. The results of this study are to be applicable to an environment friendly ubiquitous service model of u-City.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.175-183
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• 2017

In this study, the LINC project is finished and a new LINC+ has begun. For the settlement of mutual cooperation in universities and corporations, the main agenda of LINC+ project, this research attempts to find factors that are important to industries rather than the measurement of performance closely related to universities. From the companies' perspective, it is not easy to measure how much they are benefiting from mutual cooperation, although there are quantitative performance determinants such as sales, employment and export growth. Therefore, while estimating the satisfaction of industrial-educational cooperation and simultaneously estimating the satisfaction's effect to the development of companies, we try to estimate the contribution of satisfaction towards company development through subjective indicators. Through these efforts, we will raise the credibility of government policies through the cultivation of talented individuals who are customized to the industry through the cultivation of "Industry-Leading Universities" that we intend to pursue through the implementation of LINC+ business, and small and medium enterprises. Innovative support and the cooperation of industry-universities will increase job creation and ensure consistent industry. We will contribute to the mutual development of universities and industries.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.350-356
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• 2017

With increasing attention to real-time body detection, active research is being conducted on human body detection based on skin color. Despite this, most existing skin detection methods utilize static skin color models and have detection rates in images, in which colors are distorted. This study proposed a method of detecting the skin region using a fuzzy classification of the gradient map, saturation, and Cb and Cr in the YCbCr space. The proposed method, first, creates a gradient map, followed by a saturation map, CbCR map, fuzzy classification, and skin region binarization in that order. The focus of this method is to rigorously detect human skin regardless of the lighting, race, age, and individual differences, using features other than color. On the other hand,the borders between these features and non-skin regions are unclear. To solve this problem, the membership functions were defined by analyzing the relationship between the gradient, saturation, and color features and generate 108 fuzzy rules. The detection accuracy of the proposed method was 86.35%, which is 2~5% better than the conventional method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.755-761
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• 2017

In railways powered by AC power, the main circuit breaker (MCB) is used for supplying the electric power to the catenary of the vehicle. Generally, the main circuit breaker is located between the pantograph and the main transformer, and the phase of the power applied to the vehicle changes according to the operation timing of the main circuit breaker. The operation of the main circuit breaker should be actively controlled according to the phase of the power source, since the phase of the power causes unintended transient states in the vehicle's electrical system in the form of an inrush current and surge voltage. However, the MCB has a delay time when it operates which is not constant. Therefore, an intelligent controller is needed to predict the operation delay time and control the opening and closing of the MCB.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.1
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• pp.125-137
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• 2011

This study aims to know whether the Accreditation of Hospitals can help to improve productivity of hospital and affect the conversion factor. Based on the Malmquist productivity Index, the productivity of accredited hospital improves. There exists an tendency that as the scores of Accreditation rises, productivity increases. Also the higher the productivity, the lower the conversion factors in the rigid statistical evidence. This evidence is independent of hospital classification, geographical distribution, grouping. This evidence supports the productivity index can be included in the fee negotiations. It also means that rather than static efficiency, the multi-year change of productivity information can be usefully combined to set a conversion factor in Korean National Insurance Contract especially in the discussion of the structural change of payment system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.5950-5957
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• 2012

CPR with minimized hands-off time is one of integral factors for the improvement of the survival rate of patients. The purpose of this study was to examine the relationship of the installation of C-steps on the main stretcher to CPR accuracy and errors. The subjects in this study were 70 paramedics in 10 firehouses in the province of C(35 for control group, 35 for experimental group), and their CPR accuracy on the main stretchers was checked. As a result, it's found that the main stretchers equipped with the C-steps served to boost the accuracy of chest compression by creating suitable environments for that in terms of height and posture(t=65.104, p=.000), to improve the accuracy of artificial respiration by providing a proper amount of ventilation(t=5.207, p=.000), and to bolster the self-confidence of the paramedics about CPR(t=-10.612, p=.000). In conclusion, the mounting of C-steps on the main stretcher is expected to be of use for the improvement of the survival rate of cardiac-arrest patients by ensuring the precise performance of high-quality CPR.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.7
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• pp.2878-2885
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• 2012

In this study, the training and sporting equipment for leg rehabilitation featuring the MR fluids is proposed. The compact MR fluid brake is designed and manufactured to apply to the rehabilitation training and sporting mechanism. The resistance characteristic of the MR fluid brake is controllable by varying the magnetic field around the fluid. Under consideration of spatial limitation, design parameters which are related with the magnetic strength are determined to maximize to a torque using finite element method. The FE analysis is performed using a commercial code, ANSYS Workbench. The proposed brake device is manufactured, and its field-dependant torque is experimentally evaluated. When the electric current is supplied, the torque of the MR fluid brake is increased and the response is very fast. Depending on the strength of the current supply, torques of the MR fluid brake also increase similar to Bingham property of MR fluid.