• Journal of Internet of Things and Convergence
• /
• v.2 no.1
• /
• pp.1-6
• /
• 2016

The IOT environment, people connected to the network, object, everything such as space (Things) generates data in real time. The information between the object collecting, sharing, are utilized. Currently health care, research in various fields such as smart home has been promoted. Also appeared concepts emphasized all things(IOE) Internet connection between the geographic space and the Internet. Human, while important connections between the objects, such as objects, studies of efficient and secure authentication technologies have been developed. In this paper, we propose a RADIUS (Remote Authentication Dial In User Service) protocol for improved mutual authentication between each object in the IOT environment.

• The Journal of Korea Robotics Society
• /
• v.12 no.4
• /
• pp.419-424
• /
• 2017

Twisted string actuators (TSAs) are tendon-driven actuators that provide high transmission ratios. Twisting a string reduces the length of the string and generates a linear motion of the actuators. In particular, TSAs have characteristic properties (compliance) that are advantageous for operations that need to interact with the external environment. This compliance has the advantage of being robust to disturbance in force control, but it is disadvantageous for precise control because the modeling is inaccurate. In fact, many previous studies have covered the TSA model, but the model is still inadequate to be applied to actual robot control. In this paper, we introduce a modified variable radius model of TASs and experimentally demonstrate that the modified variable radius model is correct compared to the conventional variable radius string model. In addition, the elastic characteristics of the TSAs are discussed along with the experimental results.

• Mass Spectrometry Letters
• /
• v.6 no.3
• /
• pp.59-64
• /
• 2015

Quadrupole ion trap mass analyzer with a simplified geometry, namely, the cylindrical ion trap (CIT), has been shown to be well-suited using in miniature mass spectrometry and even in mass spectrometer arrays. Computation of stability regions is of particular importance in designing and assembling an ion trap. However, solving CIT equations are rather more difficult and complex than QIT equations, so, analytical and matrix methods have been widely used to calculate the stability regions. In this article we present the results of numerical simulations of the physical properties and the fractional mass resolutions m/Δm of the confined ions in the first stability region was analyzed by the fifth order Runge-Kutta method (RKM5) at the optimum radius size for both ion traps. Because of similarity the both results, having determining the optimum radius, we can make much easier to design CIT. Also, the simulated results has been performed a high precision in the resolution of trapped ions at the optimum radius size.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.16 no.6
• /
• pp.58-64
• /
• 2008

An aluminum radius rod using rheo-forging method has been developed for heavy commercial vehicles to decrease vehicle unsprung weight. To design the shape of the rod, structural simulations are performed using two load cases. To evaluate durability performance of the rods, a test system which has simultaneous 3 axes actuating system is developed. And 3 axes durability test conditions are established based on vehicle field tests. Using the test systems and the conditions, the durability test is carried out and the rods have passed the test conditions of 700,000 cycles. The weight of a developed aluminum radius rod is 4.2kg and it was drastically reduced by 48.8 percent in comparison with the weight of a steel radius rod.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.11a
• /
• pp.59-62
• /
• 1999

Inception and propagation of electrical tree and properties of Partial discharge(PD) pulses accompanying with tree as a function of needle tip radius in low density polyethylene were discussed. To study on these characteristics in different tip radius, we used specimens with needle-plane electrode system made of LDPE, observed inception and propagation of electrical tree by optical microscope with computer and investigated the characteristics of the phase resolved PD pulses accompanying with propagation of electrical tree. The PD quantities detected and analysed were PD magnitude, mean phase angle, average discharge, and the statistical characteristics of the PD pulses. As the tip radius ${\gamma}$ increases, tree inception stress E$\sub$i/ converges to constance value. This result suggests that tree inception stress E$\sub$i/ increases due to stress relaxation when the tip radius is small. Branch-type electrical tree was formed When E$\sub$i/ is 640-750[kV/mm]. bush-type electrical tree when E$\sub$i/ is 370∼400[kV/mm], branch-like electrical tree when E$\sub$i/ is 370-400[kV/mm].

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.6 s.171
• /
• pp.55-60
• /
• 2005

This paper has been focused in developing of plastic lens with ultra-precision and low birefringence ability using by injection molding simulation tools. The simulation tools, $3D-Timon^{TM}\;and\;Asu-Mold^{TM}$ were applied to visualize indirectly the flow pattern of melted polymer enter the mould and the simulation results are verified as compared with the experimental results. Birefringence and polarized light generated in injection molding process was also calculated for each injection conditions and compared with .the pictures of experimented optical lens go through the polarized light plates device. A spherical radius of plastic optical lens transcribed from profile of mould core surface was measured to estimate the geometrical accuracy fer the each injection conditions. It is confirmed that the simulation results about flow pattern and polarized light area coincided in experimental results. It is known that increasing in thickness shrinkage at center of lens, the spherical radius is larger from comparing the graph measured spherical radius and the thickness shrinkage at center of lens

• Journal of Soil and Groundwater Environment
• /
• v.13 no.3
• /
• pp.15-20
• /
• 2008

The investigation on the previous paper(Jn. of KoSSGE vol.12, no.3), which proposed three empirical equations for the different aquifers was carried out. To draw out a single equation from the three different equations the mean value of the involution factors was adopted allowing different proportional coefficients for the different aquifers. On the other hand it was found that the square root value of storativity ratio, ${\sqrt{{S_p}/{S_o}}}$ in each well is almost equal to its wellbore radius ratio, ${r_e}/{r_w}$. From this fact, the proportional coefficients can be substituted with assumed aquifer storativity and a generalized empirical equation for the effective wellbore radius has been derived.

• Journal of the Korean Mathematical Society
• /
• v.58 no.6
• /
• pp.1385-1405
• /
• 2021

Let A be a positive bounded linear operator acting on a complex Hilbert space (𝓗, ⟨·,·⟩). Let ω_A(T) and ║T║_A denote the A-numerical radius and the A-operator seminorm of an operator T acting on the semi-Hilbert space (𝓗, ⟨·,·⟩_A), respectively, where ⟨x, y⟩_A := ⟨Ax, y⟩ for all x, y ∈ 𝓗. In this paper, we show with different techniques from that used by Kittaneh in [24] that $$\frac{1}{4}{\parallel}T^{{\sharp}_A}T+TT^{{\sharp}_A}{\parallel}_A{\leq}{\omega}^2_A(T){\leq}\frac{1}{2}{\parallel}T^{{\sharp}_A}T+TT^{{\sharp}_A}{\parallel}_A.$$ Here T^#_A denotes a distinguished A-adjoint operator of T. Moreover, a considerable improvement of the above inequalities is proved. This allows us to compute the 𝔸-numerical radius of the operator matrix $\(\array{I&T\\0&-I}\)$ where 𝔸 = diag(A, A). In addition, several A-numerical radius inequalities for semi-Hilbert space operators are also established.

• Tribology and Lubricants
• /
• v.36 no.6
• /
• pp.359-364
• /
• 2020

Numerical investigation of the groove trap effect with variation in the groove-edge radius of curvature is presented here. The trap effect is evaluated in a two-dimensional sliding bearing using computational fluid dynamics (CFD). This simulation is based on the discrete phase model (DPM) and standard k - ε turbulence model using commercial CFD software, FLUENT. The numerical results are evaluated by comparisons with streamlines and particle trajectories in the grooves. Grooves are applied to various lubrication systems to improve their lubrication characteristics, such as load carrying capacity increment, leakage reduction, frictional loss reduction, and preventing three-body abrasive wear due to trapping effect. This study investigates the grove trapping effect for various groove-edge radius of curvature values and Reynolds numbers. The particle is assumed to be made of steel, with a circular shape, and is injected as a single particle in various positions. One-way coupling is used in the DPM model because the single particle injection condition is applied. Further, the "reflect" condition is applied to the wall boundary and "escape" condition is used for the "pressure inlet" and "pressure outlet" boundaries. From the numerical results, the groove edge radius is found to influence the groove trap effect. Moreover, the groove trap effect is more effective when applying the groove edge radius.

• Journal of Life Science
• /
• v.18 no.11
• /
• pp.1532-1537
• /
• 2008

The purpose of this study was to investigate the effect of different arthroplasty designs on knee kinematic and lower limb muscular activation for up-stair and down-stair movement. 3-D video analysis of whole body and joint kinematics and EMG analysis of quadriceps and hamstrings were conducted. One-way ANOVAs were used for statistical analyses (p=0.05). The single-radius group exhibited more arthroplasty limb quadriceps EMG and hamstring coactivation EMG than the multi-radius group. Single-radius demonstrated more abduction angular displacement and reached peak abduction earlier than the multi-radius arthroplasty limb. The single- radius the percent body fat showed similar values in the Elderly, Single and Multi-radius group among the periods, however Control group was Lowered among the periods. Single-radius group limb also increased the quadriceps muscle activation level to produce more knee extension moment to compensate for the short quadriceps moment arm. Resting metabolic rate was significantly increased in control group in the period of LI. Energy expenditure was extremely increased in all groups except control group among the periods. We can say this is the exercise effects.