• Journal of the Korean Society of Industry Convergence
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• v.18 no.3
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• pp.181-190
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• 2015

This paper presents a new approach to control the position of robot arm in workspace a robot manipulator under unknown system parameters and bounded disturbance inputs. To control the motion of the manipulator, an inverse dynamics control scheme was applied. Since parameters of the robot arm such as mass and inertia are not perfectly known, the difference between the actual and estimated parameters was considered as a external disturbance force. To identify the known parameters, an improved robust control algorithm is directly derived from the Lyapunov's Second Method. A robust control algorithm is devised to counteract the bounded disturbance inputs such as contact forces and disturbing forces coming from the difference between the actual and the estimated system parameters. Numerical examples are shown using SCARA arm with four joints.

• Journal of Educational Research in Mathematics
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• v.13 no.1
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• pp.25-55
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• 2003

In the school mathematics, the negative numbers have been instructed by means of intuitive models(concrete situation models, number line model, colour counter model), inductive-extrapolation approach, and the formal approach using the inverse operation relations. These instructions on the negative numbers have caused students to have the difficulty in understanding especially why the rules of signs hold. It is due to the fact that those models are complicated, inconsistent, and incomplete. So, students usually should memorize the sign rules. In this study we studied on the didactical phenomenology of the negative numbers as a foundational study for the improvement of teaching negative numbers. First, we analysed the formal nature of the negative numbers and the cognitive obstructions which have showed up in the historic-genetic process of them. Second, we investigated what the middle school students know about the negative numbers and their operations, which they have learned according to the current national curriculum. The results showed that the degree they understand the reasons why the sign rules hold was low Third, we instructed the middle school students about the negative number and its operations using the formal approach as Freudenthal suggest ed. And we investigated whether students understand the formal approach or not. And we analysed the validity of the new teaching method of the negative numbers. The results showed that students didn't understand the formal approach well. And finally we discussed the directions for improving the instruction of the negative numbers on the ground of these didactical phenomenological analysis.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.275-281
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• 2001

While basic input parameters for the performance and noise of axial fan are flow rate, pressure rise, rotating speed, and fan diameter, the geometric parameters of blade are sweep angle, solidity, and camber angle. The sweep angle does not affect fan performance much, but on fan noise significantly. Solidity and camber angle are very critical design parameters acting on the fan performance directly. The solidity and camber angle are closely related, therefore they have to be carefully determined for the low-noise and high-performance fan. In This paper, different design points are selceted and also geometric parameters are deliberately changed for the comparison of fan noise. As a result, at the same performance, the input rotational speed affects radiated noise more significantly than others. When solidity and camber angle are increased more than those by iDesignFan／sup TM／ program, more noise is experienced. The blade sweep method and blade numbers at same solidity are observed to results in different levels of performance and noise.

• Korean journal of food and cookery science
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• v.12 no.3
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• pp.339-345
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• 1996

Food waste is an inverse measure of consumer acceptability of the food as served and hence a potential determinant of food qualify. The plate waste of patients was examined by a visual method at one hospital. Patients were asked to record after each item on their menu the amount consumed in quantitative terms: None, 1/4, l/2, 3/4, all. The survey showed that 65% of all patients surveyed left some of their food during hospitalization. Mean wastes for soups and meat side dishes were found to be larger than those for cooked meals and vegatable side dishes. At the same time, a questionnaire survey was used to determine the view of patients of key aspects of the hospital foodservice system. The majority of patients surveyed left their cooked meal because of low appetite, whereas patients indicated that Food is not tasty was the primary reason for leaving soups and other side dishes.'Satisfaction' scores were significantly correlated with the patients' age and appetite at the time.

• Journal of Korean Society for Atmospheric Environment
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• v.25 no.4
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• pp.339-346
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• 2009

The objectives of this study were to introduce spatial interpolation methods which have been applied in recent papers, to apply three methods (nearest monitor, inverse distance weighting, kriging) to domestic data (Ulsan cohort) as an example of estimating the personal exposure levels. We predicted the personal exposure estimates of 2,102 participants in Ulsan cohort using spatial interpolation methods based on information of their residential address. We found that there was a similar tendency among the estimates of each method. The correlation coefficients between predictions from pairs of interpolation methods (except for the correlation coefficient between nearest montitor and kriging of CO and $SO_2$) were generally high (r=0.84 to 0.96). Even if there are some limitations such as location and density of monitoring station, spatial interpolation methods can reflect spatial aspects of air pollutant and spatial heterogeneity in individual level so that they provide more accurate estimates than monitor data alone. But they may still result in misclassification of exposure. To minimize misclassification for better estimates, we need to consider individual characteristics such as daily activity pattern.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.5 s.98
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• pp.151-159
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• 1999

A self-propulsive polishing robot is proposed as a method which automates a floor polisher. The proposed robot with two rotary brushes does not require any mechanism such as wheels to obtain driving forces. When the robot polishes a floor with its two brushes rotating, friction forces occur between the two brushes and the floor. These friction forces are used to move the robot. Thus, the robot can move in any direction by controlling the two rotary brushes properly. In this paper, firstly a dynamics model of a brush is presented. It computes the friction force between the brush and the floor. Secondly, the dynamics of the proposed robot is presented by using the bush dynamics. Finally, the inverse dynamics is solved for the basic motions, such as the forward, backward, leftward, rightward motions and the pure rotaion. This paper will contribute to realize a self-propulsive polishing robot as proposed above, In addition, this paper will give basic ideas to automate the concrete floor finishing trowel, because its basic idea for motion is similar to that of the proposed robot.

• Korean Journal of Acupuncture
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• v.36 no.4
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• pp.292-299
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• 2019

Objectives : DongUiBoGam is one of the representative medical literatures in Korea. We used text mining methods and analyzed the characteristics of the indications of each meridian in the second chapter of DongUiBoGam, WaeHyeong, which addresses external body elements. We also visualized the relationships between the meridians and the disease sites. Methods : Using the term frequency-inverse document frequency (TF-IDF) method, we quantified values regarding the indications of each meridian according to the frequency of the occurrences of 14 meridians and 14 disease sites. The spatial patterns of the indications of each meridian were visualized on a human body template according to the TF-IDF values. Using hierarchical clustering methods, twelve meridians were clustered into four groups based on the TF-IDF distributions of each meridian. Results : TF-IDF values of each meridian showed different constellation patterns at different disease sites. The spatial patterns of the indications of each meridian were similar to the route of the corresponding meridian. Conclusions : The present study identified spatial patterns between meridians and disease sites. These findings suggest that the constellations of the indications of meridians are primarily associated with the lines of the meridian system. We strongly believe that these findings will further the current understanding of indications of acupoints and meridians.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.11
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• pp.507-517
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• 2020

The present research intends to examine the relationship between the Big Five personality traits and leadership initiations among the marketing executives in Delhi NCR (INDIA), and seeks to uncover the predictors of leadership initiations within personality traits. The data are collected through online survey method using different social media platforms. A sample of 233 (male =136 and female =97) marketing executive's responses were included. The data collected with the help of self-reported Big Five model inventory and leadership initiation test. The collected data were analyzed statistically by using descriptive statistics, correlation. and stepwise multiple regression analysis. The results revealed that the age of respondents inversely correlated with leadership initiation. Neuroticism revealed significant inverse correlation with leadership initiation, whereas significant positive correlations were found between extraversion, conscientiousness, agreeableness, and leadership initiations, while openness to experience revealed insignificant positive correlation with leadership initiation. Extraversion and conscientiousness appeared as the most dominant personality traits among marketing executives, irrespective of gender, that positively influenced leadership initiation and appeared as the predictor of leadership initiation. In male executives extraversion and age emerged as the predictors of leadership behavior, while in female executives extraversion and openness to experience personality traits appeared as the predictors of leadership initiation.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.12 no.3
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• pp.389-394
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• 2005

Purpose: This study was done to examine the relationship between life stress and depression, and the effect of social support of 100 Koreans living in the Phillippines. Theoretically social support is considered to mediate the relationship between lift stress and depression. Method: Data were collected from April 1 to May 30, 2002 and analysed using SAS. The first, two hypotheses were tested using Gamma, a measure of association for ordinal variables. Partial gamma was used to test the third hypothesis. Patterns of elaboration described by Babbie(1986) were selected to interpret the relationship of the three variables in the analysis. Results: 1) There was a positive relationship between life stress and depression(Gamma=.45, p=.017), and a inverse relationship between social support and depression(Gamma=-.561, p=.002). Thus the first, two hypotheses were supported. 2) When social support was controlled, the relationship between life stress and depression increased under the condition of low social support but with high social support, the relationship decreased. Conclusion: It can be interpreted that life stress is positively related to depression under the condition of low social support, however this relationship may be reversed with high social support.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.2
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• pp.17-25
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• 2013

Performance of DI diesel engine with high fuel injection method is directly related to the emission characteristics and fuel consumption. At present, diesel injection system with piezo element is replacing conventional solenoid type due to their faster electro-mechanical properties. In this study, it was investigated the sensitivity characteristics regarding internal hydraulic modeling based on the AMESim environment of piezo-driven injector The analytic parameter for this study defined such as In/Out orifice, injection hole's diameter and driven voltage on piezo stack. As the results, it was shown that these parameter influence on a fast response characteristics of piezo-driven injector. Also we found fuel pressure recovery time is faster about 0.1 ms due to larger IN orifice diameter. And larger OUT orifice diameter occurs maximum pressure drop with faster its timing of about 0.2 ms.