• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.9
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• pp.2227-2232
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• 2013

To obtain the system requirement specification in the beginning of the precision guidance system development, the effectiveness and reliability analysis for the system are necessary. The main purpose of this research is to obtain the system requirement specification for the high speed unmanned underwater vehicles by carrying out the effectiveness analysis using the modeling and simulation scheme. The effectiveness is position error for target position. Reaching accuracy is expected to be affected by the navigation sensor parameter. Assume that the navigation sensors that is consist of inertial navigation system(INS) and doppler velocity log(DVL) is the parameter. To analyze the effectiveness of each parameter, Monte-Carlo numerical simulation is performed in this research. The effectiveness analysis is carried out using circular error probability(CEP) and variance analyze scheme. Considering the cost function, the specification of the navigation sensor is provided. The cost function is consist of the INS and DVL specification and the price of those sensors.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.10
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• pp.797-805
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• 2014

The purpose of this study was to investigate the drag and lift characteristics of the cavitator of a supercavitating underwater vehicle and the pressure loss due to water intake. These investigations were performed by changing the diameter, velocity, radius of curvature of the intake, and angle of attack of the cavitator. With increasing ratio of the intake diameter to the cavitator diameter ratio($d/D_1$), the drag coefficient and the pressure loss coefficient of the water intake decreased. The greater the increase in the ratio of the intake velocity-to-free stream velocity ratio(S), the smaller was the decrease in the drag coefficient and the lift coefficient. When the intake had a radius of curvature(c), the pressure loss coefficient decreased. On the contrary, the effect of the radius of curvature on the drag coefficient was imperceptible. For angles of attack (${\alpha}$) of the caviatator in the range of $0^{\circ}$ to $10^{\circ}$, the drag coefficient and the pressure loss coefficient changed slightly, whereas the lift coefficient increased linearly with increasing angle of attack.

• Journal of the Korea Society of Computer and Information
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• v.27 no.10
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• pp.175-184
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• 2022

This study was conducted to analyze the effect of dance exercise in Aqua(AZ) and Land(ZG) environments on bone metabolism marker(BMM) and bone mineral density(BMD) and to suggested an effective exercise method to prevent osteoporosis and osteopenia. The subjects of the study were randomly assigned to an aqua zumba group (AZG, n=11), a zumba gold group (ZGG, n=13), and a control group (CG, n=12) for elderly women over 70 years age and 12 weeks, dance exercises were conducted twice time a week for 60 minutes. As a result of this study, OC was AZG(P<.001) and ZGG(P<.05), and IGF-1 was significantly increased in AZG(P<.01). However, there was no significant difference in DPD, BMD, and T-score. Therefore, dance (Zumba) exercise in Aqua and Land has positive effects on BMM and BMD in elderly women, so it is suggested as an effective intervention method to delay osteoporosis and osteopenia.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.4
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• pp.476-482
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• 2010

In this paper, we propose a robust path tracking control method for autonomous underwater vehicle with variable speed. The proposed path tracking controller consists of a kinematic controller and a dynamic controller. First, the kinematic controller computes the surge speed and yaw rate to follow the reference path with variable speed. Then the dynamic controller controls the thrust force and yaw torque to move the AUV actually. In the dynamic control, we assume that the sway speed is a disturbance. In addition the dynamic controller is designed based on sliding mode conrol. We also demonstrate the stability of the proposed control method by Lyapunov stability theory. Finally, simulation results illustrate the performance of the proposed control method.

• 월간산업보건
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• s.187
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• pp.50-52
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• 2003

우리들의 몸은 연령과 함께 쇠약해져 갑니다. 특히 40대, 50대가 되면 자신이 생각하고 있는 이상으로 몸이 쇠약해 있습니다. 유감스럽게도 연령에 의한 체력 저하는 피할 수 없겠지만, 운동부족으로 인한 체력 저하는 적절한 운동으로 예방할 수가 있습니다. 그러나 날마다 운동을 하고 있지 않던 사람이 갑자기 운동을 하기 시작하면 생각지 않았던 부상이나 사고를 일으킬 우려가 있기 때문에 적절한 운동방식, 강도, 빈도, 실시시간에 주의해서 하는 것이 중요합니다. 본 원고에서는 운동을 통한 건강관리에 있어서 부상이나 질병으로 이어지지 않도록 하기 위한 유의점을 구체적인 스포츠를 예로 들면서 해설하였습니다.

• The Journal of the Korea Contents Association
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• v.5 no.2
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• pp.177-185
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• 2005

The purpose of this study was to evaluate the effect of combined exercise on body composition, health-related fitness and blood lipid. Subjects was ten middle-aged man. The combined exercise program consisted of performed for 60min in a bout, 4 times a week at the intensity of heart rate max$(50\sim75%)$ for 12 weeks. and the change of %fat, learn body mass, body mass index, back strength, sit-up, sit and reach total cholesterol, low density lipoprotein cholesterol, triglyceride and high density lipoprotein cholesterol have been measured before and post exercise 12 weeks. Paired t-test was performed for data analysis at the 0.05 level of significance.

• Journal of Ocean Engineering and Technology
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• v.31 no.5
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• pp.371-377
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• 2017

This paper introduces a simulation-based determination method for hydrodynamic derivatives and 6DOF (degrees-offreedom) motion analysis for an underwater vehicle. Hydrodynamic derivatives were derived from second-order modulus expansion and composed of the added mass, and linear and nonlinear damping coefficients. The added mass coefficients were analytically obtained using the potential theory. All of the linear and nonlinear damping coefficients were determined using CFD simulation, which were performed for various cases based on the actual operating condition. Then, the linear and nonlinear damping coefficients were determined by fitting the CFD results, which referred to 6DOF forces and moments acting on an underwater vehicle, with the least square method. To demonstrate the applicability of the current study, 6DOF simulations for three different scenarios (L-, U-, and S-turn) were carried out, and the results were validated on the basis of physical plausibility.

• Journal of muscle and joint health
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• v.6 no.2
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• pp.317-324
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• 1999

The purpose of this study was to identify the relationship between self-efficacy and adherence of aquatic exercise in patients with chronic arthritis. Subjects were 54 patients with rheumatoid arthritis and osteoarthritis who had participated in the 6-week aquatic exercise program. The results indicated that the relationship between self-efficacy and aquatic exercise adherence in patients with chronic arthritis was statistically significant. A significant difference of self-efficacy was found between adherers and non-adherers and self-efficacy of adherer was higher than that of non-adherer(t=5.21, p=.000). Self-efficacy was significantly associated with the total duration of an aquatic exercise adherence(r=.44, p=.001). Based on these results, self-efficacy was the important factor which affect adherence of aquatic exercise in patients with chronic arthritis. Further study was suggested to identify the relationships among self-efficacy, exercise barrier and other possible factors.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.5
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• pp.469-476
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• 2008

In this paper, it is shown that an input-output (I/O) feedback linearized controller can be designed rationally by utilizing the time-scale properties of heave and pitch for an underwater vehicle. It is assumed that the dynamics of the vehicle is restricted to the vertical plane. An output-feedback control is designed, which stabilizes steady cruising paths. It is shown that the vehicle dynamics with acceleration as output becomes minimum phase. The dynamics can be transformed into a reduced system through a kind of partial linearization and singular perturbation technique. The reduced system is not only minimum phase but also exactly I/O linearizable via feedback. The I/O dynamic characteristics of the heave and pitch modes can be made linear and decoupled. Furthermore it becomes independent of cruising condition such as vehicle velocity. This study may help for designing autopilot systems for underwater vehicles.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.4
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• pp.214-224
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• 2021

Recently, as the technology of the supercavitating underwater vehicle is improved, the necessity of research for maneuvering characteristics of the supercavitating underwater vehicle has emerged. In this study, as a preliminary step to analyzing the maneuverability of a supercavitating underwater vehicle, the characteristics of cavity shapes and hydrodynamic forces generated in a supercavitating underwater vehicle with an angle of attack were evaluated numerically. First, the geometry was designed by modifying the shape of the existing supercavitating underwater vehicle. The continuity and the Navier-stokes equations are numerically solved, and turbulent eddy viscosity is solved by the k-ω SST model. The results present the characteristics of cavity shape and the hydrodynamic forces of the designed geometry with an angle of attack.