• Transactions of the Korean Society of Automotive Engineers
• /
• v.12 no.1
• /
• pp.168-173
• /
• 2004

This article describes the design of a hydraulic system for a power split type continuously variable transmission (CVT). The CVT considered here, is composed of planetary gears, clutches, and a torque converter which is mainly used for the realization of CVT function. Similar to automatic transmissions, the hydraulic system of CVT is designed for supplying hydraulic flows and pressures to each component of CVT, in order to activate the clutch engagements and torque converter operation, and to cool the drivetrain. By using the mathematical models of drivetrain, a simulation program was developed to investigate the power performance of CVT equipped vehicle and the operating conditions of each component of CVT. And the design parameters of the hydraulic system and clutches were calculated using the operating conditions and power requirements which obtained from the simulation results. Finally the hydraulic circuit design of prototyped valve body is presented based on the numerical results of this analysis.

• Journal of the Korean Society of Mechanical Technology
• /
• v.13 no.4
• /
• pp.63-69
• /
• 2011

Hull forms for catamaran type small fishing boat powered by electric motor are newly developed by experimental approaches. Model tests for two hull forms having different length are made at circulating water channel. Resistance performance and wave patterns are compared to carry out an analysis of the effect of extension of main body. The results show that the extension of main body can give better resistance performance above a certain velocity.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.23 no.2
• /
• pp.229-234
• /
• 2012

This paper presents channel measurements for wireless body area network(WBAN) and provides performance evaluation from the measurement. We measured the radio propagation in 2.45 GHz ISM band in an anechoic chamber according to various human movements and the position of transmit antennas. Two transmit antennas are mounted on different positions of human body for the purpose of comparing the diversity gain and correlation between the channels in $2{\times}1$ multiple-input single-output(MISO) systems. The experimental results show that the outage capacity is closely related with the correlation coefficient between channels in transmit diversity system.

• Journal of the Society of Naval Architects of Korea
• /
• v.55 no.4
• /
• pp.289-296
• /
• 2018

The offshore subsea platforms are connected to subsea pipelines to transport gas/oil from wells. The pipe is a multilayered structure of polymer and steel for compensating both flexibility and strength. The pipe also requires reinforcement structures to endure the extreme environmental conditions. A vertebrae structure of bend restrictors is one of the reinforcement structures installed to protect the subsea pipe from excessive bending deformations. In this study, structural behaviors of the subsea pipeline with bend restrictors are investigated by the multi-body contact analysis in Abaqus 6.14-2. Contact forces of each bend restrictor extracted from the multi-body contact analysis can be boundary conditions for topology design optimization in Altair Hyperworks 13.0 Hypermesh-Optistruct. Multiple design constraints are considered to obtain a manufacturable design with efficient material usage. Through the multi-body contact analysis with optimized bend restrictors, it is confirmed that the bending performance of the optimized design is enhanced.

• Korean Journal of Applied Biomechanics
• /
• v.13 no.3
• /
• pp.27-46
• /
• 2003

The purposes of this study were to determine the functions of actions of the limbs during each of the three support phases of the triple jump and their relationships with the performance of the triple jump. Four elite male triple jumpers were participated as subjects. The statistical analyses used were the Pearson product moment correlation coefficient for establishing relationships and simple regression analyses to determine and compare the relationships between the change of the horizontal velocity and the change of the vertical velocity during different support phases. A level of significance at p<.05 was set. The actions of the arms were responsible for about 25%, 25%, and 30% of the decrease in the horizontal velocity of the whole body center of gravity during the support phases of the hop, step, and jump, respectively. The change in the velocities of the whole body center of gravity due to the actions of the free limbs were significantly related with the whole body center of gravity during each support phase. The action of the support leg was associated with the decrease in the horizontal velocity and the increase in the vertical velocity of the whole body center of gravity during each support phase.

• Journal of the Korean Society of Physical Medicine
• /
• v.12 no.4
• /
• pp.61-71
• /
• 2017

PURPOSE: The purpose of the present study was to investigate the effects of whole body vibration exercise on balance, muscle strength and falls efficacy in the elderly. METHODS: In this blinded randomized allocation study, 27 elderly were assigned to a whole-body vibration exercise group (n=14), consisting of 25 min structured exercises for 2 days per week for 6 weeks and a control group (n=13) performing the same program without vibration. At baseline and after the 6-week intervention, balance was measured using the Korean version of the Berg balance scale (K-BBS), timed up and go (TUG) test and functional reach test (FRT). Muscle strength was determined using the 30-s chair stand test (CST). Fear of falling was assessed using the Korean version of falls efficacy scale (K-FES). Paired t-test and independent t-test were used for within and between group comparisons, respectively. RESULTS: After the intervention, the experimental group showed significantly higher changes in all the parameters (K-BBS score, TUG test, CST, K-FES score) (p<.05) compared with the control group. However, there was no significant change in all parameters in the control group (p>.05). CONCLUSION: The whole-body vibration exercise program may be helpful to improve balance, mobility, muscle performance and fear of falling in the elderly.

• Journal of Ocean Engineering and Technology
• /
• v.22 no.4
• /
• pp.84-89
• /
• 2008

It is hard to find experimental data for a model test of small high-speed planning boats. It is difficult to verify the performance seen in a model test for a high-speed boat because the ship-model scale-ratio is very small and the flow velocity of the circulating water channel and the X-carriage speed of the towing tank are restricted. Therefore most hull-form designs for high-speed small boats depend on the sea-trial test result for similar boats or evaluation through numerical calculations. This study investigated the anti-rolling effect of the stern sub-body in a 50-knot doss planning boat. To carry out this work, new model test procedures were set up in the actual sea. Using this method, the anti-rolling effect of the stern sub-body was investigated. A stern sub-body attached to a planning boat was proved to be effective in reducing the roll and pitch angle.

• Journal of Communications and Networks
• /
• v.17 no.4
• /
• pp.419-427
• /
• 2015

There have been increases in the elderly population worldwide, and this has been accompanied by rapid growth in the health-care market, as there is an ongoing need to monitor the health of individuals. Wireless body area networks (WBANs) consist of wireless sensors attached on or inside the human body to monitor vital health-related problems, e.g., electrocardiograms (ECGs), electroencephalograms (EEGs), and electronystagmograms (ENGs). With WBANs, patients' vital signs are recorded by each sensor and sent to a coordinator. However, because of obstructions by the human body, sensors cannot always send the data to the coordinator, requiring them to transmit at higher power. Therefore, we need to consider the lifetime of the sensors given their required transmit power. In the IEEE 802.15.6 standard, the transmission topology functions as a one-hop star plus one topology. In order to obtain a high throughput, we reduce the transmit power of the sensors and maintain equity for all sensors. We propose the multiple-hop transmission for WBANs based on the IEEE 802.15.6 carrier-sense multiple-access with collision avoidance (CSMA/CA) protocol. We calculate the throughput and variance of the transmit power by performing simulations, and we discuss the results obtained using the proposed theorems.

• The Korean Journal of Rehabilitation Nursing
• /
• v.20 no.1
• /
• pp.33-41
• /
• 2017

Purpose: This study is a descriptive study to analyze the relationship between the cognitive function, body image and pain, and the influencing factors on the daily life performance of brain injured patients. Methods: The study subjects were 119 inpatients with brain injury who gave informed consent. The activities of daily living (ADLs), cognitive function, pain and body image were measured by Modified Barthel Index (K-MBI), K-MMSE (Mini-Mental State Examination), Visual Analog Scale (VAS), Semantic Differential Method (SDM), respectively. Results: ADLs was significantly associated with body image, cognitive function, and pain. Multiple regression analysis showed that paralysis, consciousness, cognitive function, and pain were significant factors influencing ADLs. Overall, approximately 48% of total variability in the ADLs could be explained by the 4 variables ($R^2=.477$, p<.001). Conclusion: To improve ADLs of brain injury patients, a deeper understanding of paralysis, consciousness, cognitive function, and pain of patients is required and active nursing invention should be conducted.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.05a
• /
• pp.1032-1037
• /
• 2003

Although the holes on the shell case are very important fer the acoustic performance, it is difficult to solve the problem because the case includes thin bodies. Hence, in the past, only the method of trial and error, which depends on the engineer's intuition and experience, was available fur the design of holes. Many researchers have tried to solve the thin-body acoustic problems, since the conventional boundary element method (BEM ) using the Helmholtz integral equation fails to yield a reliable solution fer the numerical modelling of radiation anti scattering of sound from thin bodies. In the area of the analysis of thin-body acoustic problem, three approaches are generally used; the multi-domain BEM, the indirect variational BEM, and the normal derivative integral equation And there has been just a f9w study reported on the design optimization for the acoustic radiation problems by using only the conventional BEM. For the thin-body acoustics, however, no further study in the optimization fields has been reported. In this research, the normal derivative integral equation is adopted as an analysis formulation in the thin-body acoustics, and then used fur the optimization. The analytical approaches for the design of holes are proposed by using a topology optimization technique and a genetic algorithm. The proposed approaches are implemented and validated using numerical examples.