• Journal of the Korean Society for Precision Engineering
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• v.27 no.8
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• pp.62-69
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• 2010

Internal lathe machining with a boring bar is weak with respect to vibration because the bar is long and slender. Therefore, it is important to study the dynamic characteristics of a boring bar. The purpose of this study was to identify the effects of overhang and cutting conditions on the dynamic response characteristics of a boring bar. For an efficient experiment, an $L_g(3^3)$ orthogonal array was applied and the results were quantitatively analyzed by ANOVA. Overhang, feed per revolution, and depth of cut were selected as independent variables. Meanwhile, dynamic stiffness, damping ratio, damping coefficient, and acceleration were chosen as dependent variables. The vibration signal was obtained from an accelerometer attached to the boring bar, followed by visualization by a signal analyzer. The effect of overhang was found to have a significant effect on the dynamic stiffness, damping ratio, and damping coefficient, but the other variables did not. As the length of the overhang increased, the dynamic stiffness decreased and the damping ratio increased. In addition, the damping coefficient increased until the length of the overhang was 4D (where D is the shank diameter), after which it remained constant. The acceleration decreased until the overhang length was 4D, and then increased sharply when the overhang was increased further. From these results, the behavioral trend of the damping characteristics changed when its overhang length was 4D. Consequently, there is a critical point that the dynamic characteristics of boring bar change.

• Journal of Distribution Science
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• v.14 no.12
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• pp.99-105
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• 2016

Purpose - In the present study, it has become the most important necessity in our daily lives that consumers' psychological factors affect the use of smartphones, and it has been analyzed through behavioral economic approaches. In this respect, the present study is intended to apply the heuristic theory and the prospect theory among behavioral economics theories to examine how psychological factors affect consumers' product selection. Research design, data, and methodology - In the present study, using smartphone repurchase as a dependent variable, whether regulatory focus effects have interaction effects on behavioral economic theories and behavioral economic effects such as possession (ownership) effects, framing effects, and brand recollection. As an analysis method, questionnaire surveys conducted with university students in Incheon were examined through Two-Way ANOVAs using the SPSS23 package. Results - The analysis from the results are as follows. Using smartphone repurchase as a dependent variable, the main effects and interaction effects on two variables; satisfaction difference with product functions and positive framing variable were statistically significant. Using repurchase as a dependent variable was statistically significant, there was no interaction effect between the two variables; satisfaction difference with product functions and the difference of brands in possession. Using smartphone repurchase as a dependent variable, interaction effects on two variables; satisfaction difference with product functions and the lengths of product possession periods were not statistically significant. The results from the analyses of interaction effects of brand recollection and brands type were statistically significant in possession using repurchase as a dependent variable. The results from the analyses of the main effect of the brands type were statistically significant in possession using repurchase as a dependent variable. Conclusions - The implication of the present study is that it suggests the factors that became important for customers' smartphone purchase following the change in the meaning of smartphones from practical products in the past to hedonic products. Limitations of the present study are first, the study subjects are limited to students and the number of copies in questionnaires is only approximately 130, which is insufficient, so that the present study is not sufficient as a study for entire smartphone users.

• Korean Journal of Agricultural Science
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• v.43 no.3
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• pp.299-319
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• 2016

The National Forest Inventory (NFI) is important for providing fundamental data for basic forest planning and the establishment of forest policies for the purpose of implementing sustainable forest management. The purpose of this study is to present the development of Korea's NFI including legal basis, sampling design, and measured variables and to review the usage of NFI data. The survey methods and forestry statistics among the Unites States, Canada, Japan, China, and European countries were briefly compared. Total 140 publications utilizing NFI data between 2008 and 2015 were categorized with 15 subjects. Korea has conducted the NFI 6 times since 1971, but only the $6^{th}$ NFI is comparable with the fifth, the previous NFI, because the permanent sampling plots have been shared between the periods. The Korean Forestry Statistics contains only half as many variables as that of advanced countries in Forestry. More researches were needed to improve consistent measurement of diverse variables through implementation of advanced technologies. Additional data for Forest Health Monitoring since the NFI $6^{th}$ must be under quality control which will be an essential part of the inventories for providing the chronological change of forest health.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.5
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• pp.676-682
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• 2014

In this paper, precipitation echo(PRE) and non-precipitaion echo(N-PRE)(including ground echo and clear echo) through weather radar data are identified with the aid of neuro-fuzzy algorithm. The accuracy of the radar information is lowered because meteorological radar data is mixed with the PRE and N-PRE. So this problem is resolved by using RBFNN and judgement module. Structure expression of weather radar data are analyzed in order to classify PRE and N-PRE. Input variables such as Standard deviation of reflectivity(SDZ), Vertical gradient of reflectivity(VGZ), Spin change(SPN), Frequency(FR), cumulation reflectivity during 1 hour(1hDZ), and cumulation reflectivity during 2 hour(2hDZ) are made by using weather radar data and then each characteristic of input variable is analyzed. Input data is built up from the selected input variables among these input variables, which have a critical effect on the classification between PRE and N-PRE. Echo judgment module is developed to do echo classification between PRE and N-PRE by using testing dataset. Polynomial-based radial basis function neural networks(RBFNNs) are used as neuro-fuzzy algorithm, and the proposed neuro-fuzzy echo pattern classifier is designed by combining RBFNN with echo judgement module. Finally, the results of the proposed classifier are compared with both CZ and DZ, as well as QC data, and analyzed from the view point of output performance.

• Journal of International Academy of Physical Therapy Research
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• v.12 no.1
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• pp.2295-2301
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• 2021

Background: Physical therapy applied to stroke patients is recognized as a treatment that promotes function recovery, and it is a widely known fact that constant exercise should be performed. However, there are insufficient studies on exercise intensity and exercise time that can minimize side effects and maximize function recovery for exercise therapy. Objectives: To determine the effect of exercise variables on CPK generation during aerobic exercise in stroke patients and to discover how to use appropriate exercise intensity and time when conducting an exercise for function recovery in stroke patients. Design: Quasi-experimental research. Methods: This study classified subjects into three groups (low-intensity exercise group: LIE, moderate-intensity exercise group: MIE and high-intensity exercise group: HIE) according to exercise intensity, and was further classified into two groups (10-minute exercise group: 10MG and 20-minute exercise group: 20MG) according to exercise time variables within each exercise intensity group. After, the change in CPK according to exercise intensity and time was confirmed through hematological analysis. Results: In LIE and MIE, the CPK blood concentrations before and after exercise were increased in 10MG and 20MG, which was not statistically significant (P>.05). In HIE, the CPK blood concentrations before and after exercise were increased in 10MG, and it was statistically significant (P<.05). In HIE, the CPK blood concentrations before and after exercise were increased in 20MG, and it was statistically significant (P<.01). In 10MG and 20MG, the CPK blood concentrations before and after exercises were increased in all intensity group, and there was a statistically significant difference only in HIE. Conclusion: From the results of this study, considering CPK, it will be helpful to recover and improve function if the exercise intensity setting is applied in the type of moderate intensity exercise during physical therapy interventions in stroke patients.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.419-422
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• 2003

The hydraulic excavator has been a popular research object for automation because of its multi-workings and economic efficiency. The objective of this paper is to design each components and to construct boom, arm, bucket circuit. These models modeled with AMESim show us change of variables and behavior of excavator. Simulation model will be used for simulator of excavator.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.892-897
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• 2003

This paper considers the design of mixed $H_2/\;H_{\infty}$ controllers for linear time-invariant descriptor systems. Firstly, an $H_{\infty}$ and $H_2$ synthesis problem for a descriptor system are presented separately in terms of linear matrix inequalities (LMIs) based on the bounded real lemma. Then, the existence of a mixed $H_2/\;H_{\infty}$ controller by which the $H_2$ norm of the second channel is minimized while keeping the $H_{\infty}$ norm bound of the first channel less than ${\gamma}$, is reduced to the linear objective minimization problem. The class of desired controllers that are assumed to have the same structure as the plant is parameterized by using the linearizing change of variables. In addition, we show the procedure by which a obtained descriptor controller can be transformed to a non-descriptor one.

• Proceedings of the IEEK Conference
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• 2001.06c
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• pp.185-188
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• 2001

In this paper, a cascade fuzzy control method is proposed, which presents a robustness of the effect of disturbances, and in which the number of rules of the controller increase linearly instead of exponentially with the number of input variables. The proposed fuzzy control method is composed of cascade structure. Each stage has a state and a change of state, and one consequent control variable, and previous consequent control variable is an input of next stage. Simulation of the proposed controller, which is applied to the linear and nonlinear system as SISO (single-input single-output) system, showed that the proposed control method has a good control performance and robustness of disturbances compared with a conventional fuzzy control method.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.83-86
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• 1991

This paper presents a method that optimizes the teeth shape of linear induction motor. Independent variables are x-coordinate change of four nodes at each tooth, and its objective function is thrust at start. As a result, linear induction motor with high quality which its thrust increases up to 10% per pole can be designed.

• Journal of Korean Academy of Nursing
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• v.33 no.8
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• pp.1161-1170
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• 2003

Purpose. The purpose of this study was to examine the effects of a rehabilitation program on hope and self-efficacy in a sample of homeless adolescent substance abusers at a halfway house in Seoul, Korea. Methods. Five residents of a halfway house were provided with a 16-week rehabilitation program based on a cognitive-behavioral approach. To evaluate the effectiveness of the program, this study used a single-case experimental design with the variables - hope and self-efficacy - being measured at pre-, post-, and follow-up tests. Results. While three participants showed considerable positive changes in hope and self-efficacy after the program, two participants did not show any positive changes. Despite this lack of consistent patterns in the effectiveness of the rehabilitation program, there was a qualitative change in social status (such as academic and work status) for the participants at the follow-up test. Conclusion. A rehabilitation program based on a cognitive-behavioral approach may improve the hope and self-efficacy of homeless adolescent substance abusers at a halfway house and help them to reintegrate into society.