• The Journal of Korean Physical Therapy
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• v.30 no.2
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• pp.63-66
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• 2018

Purpose: The purpose of the current study was to examine the effects of exercise-induced fatigue of the plantar flexor muscle in the dominant ankle on the plantar flexor strength and postural control function of the contra-lateral side. Methods: Twenty-one young adults (male: 10, female: 11) volunteered to participate in this study. An exercise-induced fatigue protocol to induce fatigue was performed in the plantar flexor of the dominant ankle. For the fatigue protocol, the participants were instructed to raise their heels as high as possible in the position with one leg stance of the dominant lower limb, and the heel was then downed after holding for 1 second. The muscle strength of the contra-lateral plantar flexor was measured using a digital muscle strength test device, and the static and dynamic postural control were tested by acquiring the center of gravity velocity while performing one leg standing. A paired t-test was used to identify the differences between the pre- and post, and the data were analyzed using SPSS 12.0 software. Results: Comparison of the pre- and post-test data revealed a significant difference in the plantar flexor strength and dynamic postural control after exercise-induced muscle fatigue in the dominant side. On the other hand, there was no significant difference in the static postural control. Conclusion: These findings have practical implications, suggesting that unilateral muscle fatigue affects the ankle muscle strength and postural ability of the contralateral side.

• Journal of radiological science and technology
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• v.43 no.3
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• pp.187-194
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• 2020

Bone mineral density is a examination to measure the amount of bone in patients with metabolic bone disease. It is a low dose, but may cause unnecessary exposure to the gonads and other organs located in the periphery when examining the lumbar and proximal femurs. Therefore, the purpose of this study was to evaluated the exposure dose for each organ exposed during the bone mineral density through simulation, and analyzed the applicability of the subject to radiation shielding devices using 3D printing materials. As a result, the highest dose was shown at 11.47 uSv in the breast during lumbar examination and 8.98 uSv in the testis during proximal femur examination. Also, the farther away from the examination site, the lower the effect of the scattering-ray. The shielding effect of using 3D printing shielding device showed high results in proportion to the effective atomic number and specific gravity of the printing material. Among the printing materials, ABS + W showed an effect of at least 78.72 to 96.3 9% compared to the existing lead material.

• Journal of the Korean Wood Science and Technology
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• v.19 no.4
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• pp.52-61
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• 1991

In this paper, the difference of the property of absorption and desorption for five species in semi-steady state are studied. The species used are listed in Table 1 and the dimension of specimen was $8\times8{\times}T$(Tangential direction)cm and tested in various conditions. A change of average moisture content with time were measured in each cycles. The results obtained are summarized as follows. When the relative humidity in air was maximum or minimum, the distribution of moisture In wood of all specimens were illustrated by exponential curves of decrease or increased from lace 10 center of wood. From the consideration of coefficient of decrease(C), the amount of moisture change of spruce was larger than the others. The pheonomenon was considered no relation to the specific gravity in air dry, but the wood structures. The velocity of the absorption and desorption for species decreased in the order spruce(Picea sitchensis) neodobam(Fagus crenata), solsong(Tsuga heterophylla), meranti(Shorea sp.) and kaesoo(Cercidiphyllum japoicum). In case of constant temperature and water vapor pressure is changed. the amount of absorbed moisture was larger than that of constant water vapor pressure and temperature vaned. In this fact, it is considered that the property of sorption of wood is strongly influenced by vapor pressure gradient than temperature gradient.

• Communications of Mathematical Education
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• v.21 no.4
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• pp.663-676
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• 2007

In this paper we study tetrahedron's properties related with intersection of segments and planes using the principle of the lever. We analyze proof method using the principle of the lever, and describe how to prove intersection of segments and planes using the principle of the lever in tetrahedron.

• International Journal of Aeronautical and Space Sciences
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• v.12 no.4
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• pp.365-370
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• 2011

This paper presents the air-to-air missile autopilot design for a $180^{\circ}$ heading reversal maneuver during boost-phase. The missile's dynamics are linearized at a set of operating points for which angle of attack controllers are designed to cover an extended flight envelope. Then, angle of attack controllers are designed for this set of points, utilizing a pole-placement approach. The controllers' gains in the proposed configuration are computed from aerodynamic coefficients and design parameters in order to satisfy designer-chosen criteria. These design parameters are the closed-loop frequency, damping ratio, and time constant; these represent the characteristics of the control system. To cope with highly nonlinear and rapidly time varying dynamics during boost-phase, the global gain-scheduled controller is obtained by interpolating the controllers' gains over variations of the angle of attack, Mach number, and center of gravity. Simulation results show that the proposed autopilot design provides satisfactory performance and possesses good [ed: or "sufficient" or "excellent"] capabilities.

• Journal of Internet Computing and Services
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• v.8 no.4
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• pp.137-147
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• 2007

As Web-based online communities are rapidly growing, the agents in social groups need to know their measurable belief of trust for safe andsuccessful interactions. In this paper, we propose a computational model of trust resulting from available feedbacks in online communities. The notion of trust can be defined as an aggregation of consensus given a set of past interactions. The averagetrust of an agent further represents the center of gravity of the distribution of its trustworthiness and untrustworthiness. And then, we precisely describe the relationship between reputation, trust, and averagetrust through a concrete example of their computations. We apply our trust model to online internet settings in order to show how trust mechanisms are involved in a rational decision-making of the agents.

• Journal of Biosystems Engineering
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• v.26 no.1
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• pp.11-20
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• 2001

Experiments under the stationary and harvesting condition, were performed in order to investigate the vibration characteristics of a head-feeding combine. 6 degrees of freedom components of acceleration at the location of the center of the gravity, and 3 degrees of freedom components of acceleration at the location of the operator seat were measured independently. The vibration characteristics of the combine were estimated with the power spectral density of the time series data of accelerations. From this research, the following results were obtained. 1. Vibration of a head-feeding combine under the stationary condition(engine, thresher and cutter are driven without harvesting) is mainly influenced by the engine. Further, 1/3, 1/2 (sub-harmonic) frequency components of the engine are observed besides engine driving frequency component(45Hz). 2. Vibration of a head-feeding combine under the harvesting condition is influenced by the engine, threshing unit and driving unit. Namely, some kinds of vibration frequency components in harvesting are observed compared with stationary condition. Further, sub-harmonic frequency components of the engine are observed besides engine driving frequency component as same as stationary condition. From these results, it may be concluded that vibration of a head-feeding combine is characteristics of semi-periodic and nonlinear vibration.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.5
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• pp.101-109
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• 1994

Recently, four-wheel steering systems have been developed and studied as one of the latest automotive technologies for improving the handling characteristics of a vehicle. In much of the proposed four-wheel steering systems, the side slip angle at the vehicle's center of gravity is maintained at zero. This approach allows the greater maneuverability at low speed by means of counter-phase rear steering and the improved stability at high speed through same-phase rear steering. In this paper, the effects of several four-wheel steering systems are studied and discussed on the responsiveness and stability of the vehicle by using the linear analysis. Especially, the effects of the cornering stiffnesses of both front and rear wheels are investigated on the yaw velocity gain and critical speed of the vehicle.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.5
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• pp.82-91
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• 2011

In this paper, a planar model for mechanics of a vehicle/pedestrian collision incorporating road gradient is derived to evaluate the pre-collision speed of vehicle. It takes into account a few physical variables and parameters of popular wrap and forward projection collisions, which include horizontal distance traveled between primary and secondary impacts with the vehicle, launch angle, center-of-gravity height at launch, distance from launch to rest, pedestrian-ground drag factor, the pre-collision vehicle speed and road gradient. The model including road gradient is derived analytically for reconstruction of pedestrian collision accidents, and evaluates the vehicle speed from the pedestrian throw distance. The model coefficients have physical interpretations and are determined through direct calculation. This work shows that the road gradient has a significant effect on the evaluation of the vehicle speed and must be considered in accident cases with inclined road. In additions, foreign/domestic empirical cases and multibody dynamic simulation results are used to construct a least-squares fitted model that has the same structure of the analytical one that provides an estimate of the vehicle speed based on the pedestrian throw distance and the band within which the vehicle speed would be expected to be in 95% of cases.

• Journal of Broadcast Engineering
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• v.5 no.1
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• pp.123-129
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• 2000

This paper addresses a new double detection algorithm which is based on the fuzzy control in the adaptive echo canceller of communication system. In this method, the two input of the fuzzy inference for detecting double talk condition are used. The one is the cross-correlation coefficient between the error signal and the primary signal which is the summed signal of the real echo signal and the near-end signal. The other is the cross-correlation coefficient between the estimation error signal and the primary signal. The fuzzy controller made a fuzzification for two inputs by the membership functions of trapezoid and them became the composition using inference rules. The composed result is defuzzificated by the center gravity method. The output is compared with two threshold values to detect double talk and echo path variation effectively. It is confirmed by computer simulation that this fuzzy double talk detector is able to track echo path variation accurately.