• Journal of Institute of Control, Robotics and Systems
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• v.8 no.9
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• pp.747-756
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• 2002

The automatic steering system for unmanned vehicle was developed. The magnet and MR (Magnetoresistive) sensors are used for the tue detecting system. The lateral distance between sensor and the center line of the road is determined by the linearization of the distance according to the output. The PD control theory is used for the design of the controller to compare with $H_\infty$ control theory. The $H_\infty$ control theory is used for the design of the controller to reduce the disturbance. The performance of the PD controller and $H_\infty$ controller is compared in simulations and tests. The PD controller is easy to tune in the test site. The $H_\infty$ controller is robust far the disturbances in the test results.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1700-1705
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• 2003

In this paper, the automatic steering system for unmanned vehicle was developed. The vision system is used for the lane detection system. This paper defines two modes for detecting lanes on a road. First is searching mode and the other is recognition mode. We use inverse perspective transform and a linear approximation filter for accurate lane detections. The PD control theory is used for the design of the controller to compare with $H_{\infty}$ control theory. The $H_{\infty}$ control theory is used for the design of the controller to reduce the disturbance. The performance of the PD controller and $H_{\infty}$ controller is compared in simulations and tests. The PD controller is easy to tune in the test site. The $H_{\infty}$ controller is robust for the disturbances in the test results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.12
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• pp.2008-2018
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• 1997

In this study, free vibration analysis of double through-the-width split beam is studied based on the author's earlier work. Each segment which constructs double through-the-width split beam is considered as Timoshenko beam. The effect of coupling between longitudinal and transverse vibration on the natural frequencies of split beams is considered. Data acquisition and modal test of double split beam for clamped-free boundary condition are carried out. Experimental and numerical results obtained by ANSYS were compared with the calculated data by present theory and their comparisons give good agreement with one another. The influences of the size and location of double split, shear deformation, and boundary conditions on the natural frequencies are demonstrated for illustrative purpose. Effects of double split on the dynamic characteristics of beams can be used to detect the size and the location of damages in structures.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.1
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• pp.78-89
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• 1993

A new theory based on the modified momentum and energy conservation has been proposed in order to overcome the drawbacks included in previous theories which are used for the determination of dynamic yield stresses and the investigation of dynamic behavior of metals. Then the improvements suggested by the new theory have been manifested through the analysis of the error included in the measurement of deformed length and through the comparison between the new theory, existing theories, and experimental results performed by previous workers. Meanwhile rod impact test has been performed which uses a compressed- air system for the acceleration of flat-ended cylindrical free-cutting brass rods. From the geomtrical measurements of deformed length, the dynamic yield stress of free-cutting brass has determined.

• Journal of Korean Academy of Nursing
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• v.35 no.7
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• pp.1362-1370
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• 2005

Purpose: The purpose of this study was to identify the degree of attaining a smoking cessation goal when an agreement on means to achieve smoking cessation among male college student smokers was established. Method: This study was planned as a nonequivalent control group non-synchronized design and the sample was divided into an agreement group and a comparison group by convenience sampling in a college of G city. The data was analysed with SPSS Win10.0 using a Likelihood $x^2-test$, Odds ratio, Paired t-test and ANCOVA. Result: The theory that the degree of smoking cessation will be higher in the agreement group than the Comparison group was rejected (${\delta}$ = 2.567, p = .055). The theory that nicotine dependency will be lower in the agreement group than the comparison group was supported (F = 3.965, P = .049); however, the theory that the number of cigarettes smoked per day will be lower in the agreement group than the comparison group was rejected (F = 1.342, p = .252). Conclusion: It has been shown that an agreement on means to achieve smoking cessation goals is a key factor to success in quitting smoking.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.9
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• pp.341-349
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• 2021

This study is conducted to fill the research gap in proposing and testing the relationship between "Attitudes about the overall image of the destination", "Subjective norms" and "Perceived behavioral control". Simultaneously, we examine the relationship between these variables and tourists' "intent to choose a destination.". While most previous studies only deal with the relationship between destination image and intended behavior of tourists, this study uses the theory of planned behavior (Ajzen, 1991) to explain the intended behavior of tourists. In addition, the Theory of Destination Image (Echtner & Ritchie, 1991) is used to explain the factor "attitudes about the overall image of the destination", contribute to supplementing and perfecting the Theory of Planned Behavior. This study uses a Structural Equation Modeling (SEM) to analyze a sample of 993 observations, the subjects of which are international tourists to Vietnam, to test the relationship between second-order constructs. The test results show that "Subjective norms" and "Perceived behavioral control" have an impact on "Attitudes about the overall image of the destination". Moreover, all these three factors have an impact on "Intent to choose destination", in which the factor "Perceived behavioral control" has the greatest impact on "intention to choose destination".

• The Journal of Asian Finance, Economics and Business
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• v.8 no.1
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• pp.45-52
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• 2021

The capital structure is one of the hot financial topics among researchers and scholars. Its importance comes from the fact that capital structure is closely related to companies' ability to meet different stakeholders' needs. A suitable capital structure will boost the business and create a competitive advantage in the context of fierce competition. Many companies choose an optimal debt level based on the trade-off between interest and debt costs. This study aimed to test the existence of trade-off theory in capital structure, the case of Vietnam's real estate companies, which are growing very fast recently. Instead of considering constant optimal leverage to test the trade-off model, we take advantage of the dynamic capital structure determined by growth opportunities, profitability, tax incentives, tangibility, liquidity, and firm size. The dynamic panel data regression was estimated by the system Generalized Method of Moment (Sys-GMM). The empirical evidence showed that real estate companies listed in the Vietnamese stock market might change their leverage toward a target capital structure determined by influential factors in a long-term perspective. In particular, the debt-to-asset ratio will change by approximately 14 percent, positively, in response to the difference between the current debt-to-asset ratio and the dynamic target debt-to-asset ratio.

• The Journal of Korean Society for School & Community Health Education
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• v.22 no.2
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• pp.25-40
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• 2021

Objectives: The purpose of this study was to examine effects of health promotion program based on self-efficacy theory on physiological indicators, self-efficacy, grits, and health promotion behavior in community elderly. Methods: A non-equivalent control group pre-post test design was used. The intervention group received the health promotion program based on self-efficacy theory for 8 weeks from October 8 to November 26, 2020. Results: t-test showed that systolic blood pressure (t=-2.12, p=.040), self-efficacy (t=3.78, p<.001), grit (t=3.75, p<.001) and health promotion behavior (t=2.89, p=.002) were significant differences between the two groups. In other hands BMI (t=-1.26, p=.213), diastolic pressure (t=-1.07, p=.287), total cholesterol (t=-1.67, p=.102), LDL-cholesterol (t=-0.76, p=.451), HDL-cholesterol (t=-0.57, p=.567) and triglyceride (t=-1.76, p=.094) were no significant difference between two groups. Conclusions: The health promotion program based on self-efficacy theory was found to be an effective nursing intervention program in improving physiological indicators, self-efficacy, grit and health promotion behaviors of community elderly.

• Computers and Concrete
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• v.30 no.4
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• pp.289-299
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• 2022

Based on the random cracking theory, the cylinder RVE model of reinforced concrete is established and the damage process is divided into three stages as the evolution of the cracks. The stress distribution along longitude direction of the concrete and the steel bar in the cylinder model are derived. The equivalent elastic modulus of the RVE are derived and the user-defined field variable subroutine (USDFLD) for the equivalent elastic modulus is well integrated into the ABAQUS. Regarding the tensile rebars and the concrete surrounding the rebars as the equivalent homogeneous transversely isotropic material, and the FEM analysis for the reinforced concrete beams is conducted with the USDFLD subroutine. Considering the concrete cracking and interfacial debonding, the macroscopic damage process of the reinforced concrete beam under four-point bending loading in the simulation. The volume fraction of rebar and the cracking degree are mainly discussed to reveal their influence on the macro-performance and they are calibrated with experimental results. Comparing with the bending experiment performed with 8 reinforced concrete beams, the bending stiffness of the second stage and the ultimate load simulated are in good agreement with the experimental values, which verifies the effectiveness and the accuracy of the improved finite element method for reinforced concrete beam.

• Journal of Ocean Engineering and Technology
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• v.38 no.1
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• pp.1-9
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• 2024

The vertical center of gravity (VCG) has a significant impact on the roll motion response of a surface ship, particularly oil tankers based on the oil level in the tanker after discharging oil at several stations or positional changes, such as changes in the superstructure and deck structure. This study examined the motion response of the Korea very large crude carrier 2 (KVLCC2) at various VCGs, especially roll motion when the VCG changed. The potential theory in the Ansys AQWA program was used as a numerical simulation method to calculate the motion response. On the other hand, the calculations obtained through potential theory overestimated the roll amplitudes during resonance and lacked precision. Therefore, roll damping is a necessary parameter that accounts for the viscosity effect by performing an experimental roll decay. The roll decay test estimated the roll damping coefficients for various VCGs using Froude's method. The motion response of the ship in regular waves was evaluated for various VCGs using the estimated roll-damping coefficients. In addition, the reliability of the numerical simulation in motion response was verified with those of the experiment method reported elsewhere. The simulation results showed that the responses of the surge, sway, heave, pitch, and yaw motion were not affected by changing the VCG, but the natural frequency and magnitude of the peak value of the roll motion response varied with the VCG.