• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.19 no.4
• /
• pp.1-5
• /
• 2011

The free-wing tilt-body aircraft is researched in the flight performance characteristics for center of gravity (CG) change. All of speed, body tilt angle and center of gravity change are simulated to determine the flight envelope by a non-linear 3-DOF mathematical model. In flight, this aircraft configuration changes by the tiltable empennage. Then, flight dynamics distinguishes from those of a conventional fixed-wing aircraft. Though flight performance and trimmability are studied by CG change, the flight model of free-wing tilt-body aircraft is to reduce the hidden risk and to achieve the successful flight test. It is analyzed the flight characteristics by CG change that distinguishes free-wing tilt-body aircraft from the conventional aircraft.

• Journal of the Society of Naval Architects of Korea
• /
• v.58 no.3
• /
• pp.158-166
• /
• 2021

In this paper, a numerical analysis technique using a body force model is investigated to estimate the available net thrust of multi-pod-driven ice-breaking vessels under bollard pull and overload conditions. To employ the body force model in present flow simulations, drag and thrust components acting on the pod unit are calculated by using Propeller Open Water (POW) test data. The available net thrusts according to the direction of operation are evaluated in both bollard pull and overload conditions under deep water. The simulation results are compared with the model test data. The available net thrusts, calculated by the present analysis for ahead operating modes at 3~6 knots which are typical speeds of the target vessel in arctic field, are agreed well with the model test results. It is also found that the present result for astern operating mode appears approximately 6 % larger than the model test result. In addition, the available net thrusts are calculated under the both operating conditions accompanied by shallow water effects, and the main cause of the difference is studied. Based on the result of the present study, it is confirmed that the body force model can be applied to the performance evaluation of multi-pod propulsion system and the main engine selection in early design stage of the vessel.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.39 no.10
• /
• pp.1039-1044
• /
• 2015

During the development of vehicles, durability tests are time consuming and costly. Recently, automobile companies have attempted to develop their own durability evaluation procedures by modifying and complementing . In this paper, we propose an integrated computer-aided engineering (CAE) method to evaluate the durability of a torsion beam axle (TBA). We compare this method with the standardized durability evaluation method used by an actual automobile company in order to determine the feasibility of this method. We compare the results with the test result data to enable us to estimate the reliability of the analysis results. In this study, we analyze the processes and results of the quasi-static fatigue analysis, and found improved methods and problems. Furthermore, we perform a thorough test using the requirements of the actual company. Based on the results, the structural analysis process in the quasi-static fatigue analysis method was superseded by the multi-body dynamics analysis process. Generally, this method is referred to as the resonance-fatigue analysis method.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.9
• /
• pp.1069-1075
• /
• 2013

An effective method is necessary for the real-time analysis of an unmanned military robot. To achieve highly efficient simulations, a subsystem synthesis method has been developed. The subsystem synthesis method separately generates equations of motion for the base body and for the subsystem. The equations of motion are expressed by DAE, which consist of differential equations and algebraic equations. To increase the accuracy and efficiency of solutions, DAE solvers such as the Direct, CS (Constraint Stabilization), and GCP (Generalized Coordinate Partitioning) method are employed. In this study, the subsystem synthesis method is applied for effective multi-body dynamics analysis of an unmanned military robot, and a comparative study of three different DAE solvers is carried out.

• Journal of Internet Computing and Services
• /
• v.12 no.1
• /
• pp.27-38
• /
• 2011

In this paper, we propose a multiple access scheme using MHP(Modified Hermite Polynomial) pulse and ternary code for high-data and low-data rate for Out-body WBAN(Wireless Body Area Network). To satisfy the requirement of WBAN system, UWB-IR has been considered as a promising candidate for Out-body WBAN. The proposed multiple access scheme, using orthogonal MHP pulse and ternary code sets, reduces multi-user interference and distinguishes user signal from multi-user signals. We propose two algorithms for synchronous and asynchronous WBAN system. The symbol is constructed by MHP pulses and time hopping duration to reduce multi-user interference in the synchronous WBAN system. The symbol also is constructed by ternary code to avoid collision between pulse trains in the asynchronous WBAN system. The results of the proposed multiple access scheme show a clear improvement of BER.

• Journal of Institute of Control, Robotics and Systems
• /
• v.8 no.6
• /
• pp.477-483
• /
• 2002

This paper deals with a workspace analysis of multi-legged walking robots in velocity domain(velocity workspace analysis). Noting that when robots are holding the same object in multiple cooperating robotic arm system the kinematic structure of the system is basically the same with that of a multi-legged walking robot standing on the ground, we invented a way ot applying the technique for multiple arm system to multi-legged walking robot. An important definition of reaction velocity is made and the bounds of velocities achievable by the moving body with multi-legs is derived from the given bounds on the capabilities of actuators of each legs through Jacobian matrix for given robot configuration. After some assumption of hard-foot-condition is adopted as a contact model between feet of robot and the ground, visualization process for the velocity workspace is proposed. Also, a series of application examples will be presented including continuous walking gaits as well as several different stationary posture of legged walking robots, which validate the usefulness of the proposed technique.

• Investigative Magnetic Resonance Imaging
• /
• v.23 no.2
• /
• pp.148-156
• /
• 2019

Hyperglycemia-induced hemichorea (HGHC) is a rare but characteristic hyperkinetic movement disorder involving limbs on one side of the body. In a 75-year-old woman with a left-sided HGHC, conventional brain MR imaging showed very subtle T1-hyperintensity and unique gadolinium enhancement in the basal ganglia contralateral to movements. Multi-parametric MRI was acquired using pulse sequence with quantification of relaxation times and proton density by multi-echo acquisition. Myelin map was reconstructed based on new tissue classification modeling. In this case report of multi-parametric MRI, quantitative measurement of myelin change related to HGHC in brain structures and its possible explanations are presented. This is the first study to demonstrate myelin loss related to hyperglycemic insult in multi-parametric quantitative MR imaging.

• Korean Journal of Health Education and Promotion
• /
• v.21 no.3
• /
• pp.53-66
• /
• 2004

Purpose: To compare differences in BMI, body weight perception and satisfaction, and eating behavior by gender among middle school students. Methods: From 19 middle schools in W city four classes in two middle schools were selected by cluster sampling with multi-stage sampling. A structured questionnaire was answered by 143 adolescents. Results: Differences in BMI between boys and girls were significant (x$^2$=13.15, p=.00l). Boys reported higher ideal body weight than girls (t=6.33, p<.000l), and discrepancy between ideal body weight and body weight perception in girls was significantly greater than in boys(t=-5.0l, p<.0001). There was no significant gender difference in body weight perception but more boys were satisfied with their body weight(t=-4.48, p<.0001). Comparison of eating behavior showed that girls reported high scores in disinhibition (t=-2.29, p<.05) and hunger (t=-2.81, p<.01), while boys reported higher scores in cognitive restraints (t=3.22, p<.01). Conclusion: Interventions to help girls improve body image and satisfaction with body image are crucial. In order to establish proper diet habits and balanced nutritional status for adolescents, educational interventions should address characteristics of eating behaviors.

• Applied Microscopy
• /
• v.18 no.2
• /
• pp.141-152
• /
• 1988

The developmental processes of the protein body are studied on endosperm cells of Panax ginseng during seed maturation periods. The spherosome, mitochondria, rough endoplasmic reticulum, and ribosome are observed and then are gradually increased in early endosperm cells. Protein body developed from vesicles produced by the rough endoplasmic reticulum and was formed at the enlarged ends of rough endoplasmic reticulum. Also, vacuole-like protein body was observed in associated with rough endoplasmic reticulum. Golgi complex is observed in associated with vacuole and its vesicles containing proteinaceous granules moved and accumulated to the vacuole. Proteinaceous granules are deposited in the spherical or oval shaped vacuole and gradually, vacuole is surrounded by the multi-membranous structure. Rough endoplasmic reticulum, ribosome, Golgi complex, and vacuole are observed in associated with protein body formation.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.1177-1182
• /
• 2004

The physical model considered here is a horizontal layer of fluid heated below and cooldabove with a heat-generating conducting body placed at the center of the layer. The body genrates a constant amount of heat as initial condition. Two-dimensional solution for unsteady natural convection is obtained using an accurate and efficient Chebyshev spectral methodology for various of Rayleigh number from $10^3$ to $10^6$. Multi-domain Technique is used to handle heat-generating conducting body. The results for the case of heat-generating body are also compared to those of adaibatic body.