• Research in Mathematical Education
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• v.14 no.1
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• pp.79-98
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• 2010

To analyze the relationships between self-control, thinking quality and mathematical academic achievement, 197 senior school students were asked to complete questionnaires called "self-control ability on mathematics for middle school students" and "thinking quality for senior school students." The results were as follows: (1) There was strongly positive relevance between self-control ability, thinking quality and mathematical academic achievement. (2) A model was presented in which self-control ability had a direct impact on mathematical academic achievement, meanwhile had indirectly influenced mathematical academic achievement by thinking quality which acted as the intermediate variable. Thinking quality had a direct impact on mathematical academic achievement, too. (3) There's no significant difference between the two groups of boys and girls on the structural weights.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.601-606
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• 1992

In this paper, we consider an optimal guidance problem with both the terminal impact angle and control constraints in addition to the usual zero miss distance constraint. We first present the optimal solution of the problem for the missile of an arbitrary order, and show that it is a linear combination of a step response and a ramp response of the missile. Therefore the usual practice of using the control obtained by saturating the optimal solution for the case of unlimited control may result in a large terminal miss. A method called the initial command saturation is suggested to reduce this terminal miss, where the control in the initial phase of guidance is forced to be saturated until a certain condition for a guidance variable is met.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.6
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• pp.497-506
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• 2015

A composite guidance law for impact angle control against nonstationary nonmaneuvering targets is proposed. The proposed law is based on the characteristics of proportional navigation and generates two kinds of guidance commands during the homing phase. The first command is to keep the desired look angle, and the second is to attack the target with impact angle constraint. The switch of guidance phases occurs when the specific light-of-sight(LOS) angle determined from the engagement information is satisfied. The calculation method of the maximum achievable impact angle is also proposed to design easily the desired impact angle within the missile capability. Numerical simulations are performed to investigate the performance and characteristics of the proposed law.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2017.05a
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• pp.401-402
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• 2017

• Nuclear Engineering and Technology
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• v.26 no.2
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• pp.197-204
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• 1994

In a PWR rod cluster control assembly(RCCA) for shutdown is released upon action of control rod drive mechanism and falls down through the guide thimble by its weight. Drop time and impact velocity of the RCCA are two key parameters with respect to reactivity insertion time and the mechanical integrity of fuel assembly. Therefore, the precise control of drop time and impact velocity is prerequisite to modifying the existing design features of the RCCA and guide thimble or newly designing them. During its falling down into the core, the RCCA is retarded by various forces acting on it such as fluid resistance caused by the RCCA movement, buoyance and mechanical friction caused by contacting inner surface of the guide thimble, etc. However, complicated coupling of the various forces makes it difficult to derive an analytical dynamic equation for the drop time and impact velocity. This paper deals with the development of a computer program containing an analytical dynamic equation applicable to the Korean Fuel Assembly(KOFA). The computer program is benchmarked with an available single control rod drop tests. Since the predicted values are in good agreement with the test results, the computer program developed in this paper can be employed to modify the exiting design features of the RCCA and guide thimble and to develope their new design features for advanced nuclear reactors.

• Asia-Pacific Journal of Business
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• v.10 no.3
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• pp.125-142
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• 2019

The study wanted to verify the effect of emotional sub-compression, a negative variable of emotional labor, on job performance, on security personnel working at private security companies, and further to verify how the impact on emotional sub-compression can affect job performance through the first draft of regulation. Empirical analysis through the study model showed that emotional edema was not a significant effect, but a negative effect on job performance, and that it did not affect the control focus itself. This revealed that emotional harmony has been shown to have a negative impact on performance due to the present state and conflicting situations in one's emotions, which means that emotional harmony does not affect negative or positive effects depending on a person's attributes. It also showed that the temperamental control focus on job performance had a positive impact on employees with an improvement focus and had a negative impact on employees with a preventive focus, and that a temperamental control focus between emotional dissonance and job performance had an effect. This indicated that job performance was affected by a temperamental control focus and that employees with an improvement focus had a positive effect and had a positive effect on performance. The implications of the study in this study are that it can have target differentiation in the areas where the study was conducted on guard workers, a social issue related to the study of emotional labor, and it can be meaningful that the study of emotional labor had a control focus and measured both positive and negative tendencies. It is also believed that there will be contributions to the verification of differences in performance resulting from employee propensity and by linking it with a variable called emotional instability. However, the data collected have the limitations of the subject and region, and the emphasis on cross-sectional analysis and the representative of the various emotions to verify the negative effects of emotional labor, and the problem of securing reliability related to the adjustment focus verification are the limitations of the research.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.8
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• pp.737-742
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• 2015

Course correction munition are a weapson system for precision attacks and are assembled by applying a ballistic control system to existing projectiles. The roll control system is a subsystem of the ballistic control system and is placed between the guidance and control units inside of the projectile, which undergoes a 5000g lateral acceleration. Thus, it is very important to design the system to endure this load. Many developed countries evaluate the performance and safety of course correction munitions' parts using live-fire gun launch tests or a soft recovery system. However, these methods are expensive and slow. Thus, in this study, we develop impact analysis model of the roll control system using CAE. We apply the code to simulate impact phenomenon and use Johnson-Cook material model for modeling the high strain rate effect on the materials. We also design bearings in detail to analyze their behavior and verify the reliability of CAE model through gas-gun impact tests of the roll control system.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.4
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• pp.719-728
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• 2017

This paper proposes a synthesis of new guidance law to generate an evasive maneuver against enemy's missile interception while considering its impact angle, acceleration, and field-of-view constraints. The first component of the synthesis is a new function of repulsive Artificial Potential Field to generate the evasive maneuver as a real-time dynamic obstacle avoidance. The terminal impact angle and terminal acceleration constraints compliance are based on Time-to-Go Polynomial Guidance as the second component. The last component is the Logarithmic Barrier Function to satisfy the field-of-view limitation constraint by compensating the excessive total acceleration command. These three components are synthesized into a new guidance law, which involves three design parameter gains. Parameter study and numerical simulations are delivered to demonstrate the performance of the proposed repulsive function and guidance law. Finally, the guidance law simulations effectively achieve the zero terminal miss distance, while satisfying an evasive maneuver against intercept missile, considering impact angle, acceleration, and field-of-view limitation constraints simultaneously.

• Transactions of Materials Processing
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• v.24 no.6
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• pp.425-430
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• 2015

In the current paper, the effects of initial slug design on the earring of an Al rectangular battery case manufactured by impact extrusion were studied. During impact extrusion, non-uniform metal flow between the long and the short sides of the battery case leads to earring, which is subsequently trimmed. Process parameters such as friction, aspect ratio of the battery case, the die shape and the forming temperature tend to induce earring because they cause greater non-uniform metal flow. Large aspect ratio of the battery case and high friction between slug and die can greatly affect the earring of a rectangular battery case. To make a rectangular battery case without earring, it is necessary to control metal flow uniformly during impact extrusion. One of the ways to reduce the earring is to control the metal flow of slug at the initial upsetting stage. To analyze the effects of the initial slug design on earring, FE analysis was conducted using DEFORM 3D. Two types of initial slug designs were evaluated where volume was removed along either the width or thickness directions. The results show that the initial slug design can be effective in adjusting the uniformity of metal flow.

• Korean Journal of Child Studies
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• v.32 no.5
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• pp.67-84
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• 2011

This study examined the effects of parental control and children's autonomy on self-esteem, using a sample of 415 school-age children (208 boys and 207 girls) recruited in Seoul. Ordinary Least Square regressions revealed a variety of gender-based differences in the associations among these three variables. Boys with high maternal behavioral control had high levels of self-esteem, whereas girls under low paternal psychological and high behavioral control reported high levels of self-esteem. Boys with high maternal behavioral control and girls with high paternal behavioral control also reported high levels of autonomy. Autonomy was found to exert a positive impact on self-esteem for both boy and girls. Autonomy played a mediating role in the relationships between maternal behavioral control and self-esteem for boys, and between paternal behavioral control and self-esteem for girls. These findings highlight the differential influences of psychological control and behavioral control on autonomy and self-esteem, as well as the relative impact of the opposite sex parent on the development of autonomy and self-esteem in late childhood.