• Progress in Superconductivity and Cryogenics
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• v.7 no.2
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• pp.35-38
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• 2005

One of the most serious problems in KEPCO system operation is higher fault current than the SCC(Short Circuit Capacity) of circuit breaker. There are many alternatives to reduce the increased fault current such as isolations of bus ties, enhancement of SCC of circuit breaker, applications of HVDC-BTB(Back to Back) and FCL(fault current limiter). But, these alternatives have some drawbacks in viewpoints of system stability and cost. As the superconductivity technology has been developed, the resistance type HTS-FCL(High Temperature Superconductor Fault Current Limiter) can be one of the most attractive alternatives to solve the fault current problem. To evaluate the accurate transient performance of resistance type HTS-FCL, it is needed that the dynamic simulation model considering transient characteristics during quenching and recovery state. Under this background, this paper presents the EMTDC model for resistance type HTS-FCL considering the nonlinear characteristic of final resistance value when quenching and recovery phenomena by fault current injection and clearing occurs.

• Transactions of Materials Processing
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• v.10 no.4
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• pp.347-354
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• 2001

Compression tests were carried out to investigate the hot-deformation behavior of Ti-6Al-4V alloy in the temperature range of $915^{\circ}C$ to $1015^{\circ}C$ and the strain rate range of $10^{-3}s^{-i}$ to $10s^{-1}$. Under the given test conditions, the hot-deformation of Ti-6Al-4V alloy was mainly led by dynamic recovery rather than by dynamic recrystallization. The activation energy for the plastic deformation in $\alpha+\beta$ field was about 894 kJ/mol and $\beta$ field was 332kJ/mo1. Processing map for hot working are developed on the basis of the variations of efficiency of power dissipation($\eta$=2m/m＋1) and flow instability criterion using the dynamic material model. The optimum process condition in the ($\alpha＋\beta$) field was obtained at the temperature ranges of $930^{\circ}C$ to $955^{\circ}C$$^{\circ}C$ and a strain rate of $10^{-3}s{-1}$.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.4
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• pp.39-52
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• 2000

A design of 2 stage S-DLVA(successive detector log video amplifier) was studied to detect wide dynamic radar pulse ranging from -70 ㏈m to 0㏈m. A basic design idea was focused on the linear detection in logarithmic scale of wide dynamic range radar pulses from nosie-like weak power of -70 ㏈m to relatively high power 0 ㏈m. It is highly formidable, since it requires high speed detection less than 10 nsec over the operating frequency ranges from 6 to 18 ㎓. A limiter diode, a tunnel diode and an L17-C were used as a protecting device, a detector diode and a log video amplifier in companion as a single stage detector to give voltage output proportional to the input power of about 35 ㏈ dynamic range. A protype of 2-stage DLVA having one more single stage detector was fabricated with a 32 ㏈ low noise amplifier and a 3 ㏈ hybrid coupler to provide total 70 ㏈ dynamic range detection. The logging characteristics were measured to have log slope of 25m.V/㏈ against 70 ㏈ logging range from -55 ㏈m to +15 ㏈m, the log linearity of within +/- 1.5 ㏈, and tangential sensitivity was at -63 ㏈m. The pulse dynamics of rise time and recovery time were measured as 50 nsec and 1.2 $\mu$sec, respectively. The reason might be due to the parasitic capacitances of packaged limiter, tunnel diode, and L17-C.

• Korean Journal of Metals and Materials
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• v.46 no.9
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• pp.563-571
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• 2008

The influence of annealing treatment on dynamic deformation behavior of ultra-fine grained aluminum alloys was investigated in this study. After equal-channel angular pressing at $200^{\circ}C$, most of the grains were considerably reduced to nearly equiaxed grains of $0.3{\mu}m$ in size. With an increment of various annealing treatments for 1 hour, resultant microstructures were found to be fairly stable at temperatures up to $200^{\circ}C$, suggesting that static recovery would be dominantly operative, whereas grain growth was pronounced above $250^{\circ}C$. The tensile test results showed that yield and ultimate tensile strengths decreased, but elongation-to-failure and strain hardening rate increased with increasing annealing temperature. The dynamic deformation behavior retrieved with a series of torsional tests was explored with respect to annealed microstructures. Such mechanical response was analyzed in relation to resultant microstructure and fracture mode.

• Physical Therapy Rehabilitation Science
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• v.11 no.4
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• pp.421-429
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• 2022

Objective: The purpose of this study was to compare and analyze the effects of arch support taping on static balance, static/dynamic foot contact area, and ground reaction force during walking according to the types of elastic tapes with mechanical elasticity differences. Design: Cross-sectional study Methods: Twenty-six participants selected for flexible flat feet through the navicular drop test were randomly assigned to non-taping, Dynamic-taping, and Mechano-taping conditions. Static balance and foot contact area were compared in the standing posture according to arch support taping conditions, and foot contact area and ground reaction force were compared during walking. Results: There was no significant difference in static balance according to the taping condition in the standing position, but the foot contact area in the Mechano-taping condition showed a significant decrease compared to the non-taping condition (p<0.05). The foot contact area during walking significantly decreased in the Dynamic-taping and Mechano-taping conditions (p<0.05), but there was no significant difference between the ground reaction force. Conclusions: Based on the results of this study, it was confirmed that among the types of elastic taping, arch support taping using dynamic taping and Mechano-taping has the effect of supporting the arch with high elastic recovery. Any type of elastic tape can be used for arch alignment in flexible flat foot.

• Journal of KIISE:Information Networking
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• v.35 no.3
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• pp.215-226
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• 2008

As sensor networks are used in various and dynamic applications, the function of sink-to-sensors reliable multicasting such as for task reprogramming is newly required. NAK-based error recovery schemes have been proposed for energy efficient reliable multicasting. However, these schemes have incompleteness problems such as the last packet loss. This paper introduces an ACK-based error recovery scheme, RM2I(Reliable Multicast with Implicit ACK and Indirect Recovery). It utilizes wireless multicast advantage in which a packet may be delivered to all of its omni-directional neighbor nodes. When a sender overhears a packet which its receiver forwards to the next nodes, it may interpret it as an ACK from the receiver. We call it an Implicit ACK. In Indirect Recovery, when a node receives a packet from neighbor nodes which are not its direct upstream node, it saves and utilizes it for error recovery. Using NS-2 simulator, we have analyzed their effects. We have also compared RM2I with the NAK-based error recovery scheme. In results, RM2I shows comparable performances to the ideal NAK-based scheme, except where Implicit ACK and Indirect Recovery do not occur at the edges of the networks.

• Journal of the Korean Society of Physical Medicine
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• v.18 no.4
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• pp.121-131
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• 2023

PURPOSE: The purpose of this study was to evaluate the effects of ice and hot packs on proprioception, balance, and muscle strength in knee extensor muscle fatigue. METHODS: A total of 31 male and female students in their twenties from a university in A, Chungnam, Korea, were selected as participants. Three experiments were conducted to assess static balance, dynamic balance, proprioception, and muscle strength before and after induction of muscle fatigue, and following intervention. RESULTS: In the case of stability typical (ST), a significant difference was observed in pillow with eye open (PO) when a Hot pack was applied (p < .05). The weight distribution index (WDI), showed significant differences in normal eye open (NO) and Normal eye closed (NC) tests when ice packs and hot packs were applied (p < .05). In the dynamic balance assessment using Y-balance, significant differences were observed in all values except for pre- and post-intervention in the medial and lateral directions (p < .05). The recovery of proprioceptive sensation showed a significant difference when ice packs were applied (p < .05). In muscle strength, significant differences were observed in all comparisons between measurement time points (p < .05). CONCLUSION: Rest was most effective for static balance, and cold and warm compresses were most effective in recovering dynamic balance. For proprioception, cold compresses were most effective. Muscle strength had a positive effect on recovery in all three intervention methods. These results show that cold and warm compresses can be useful in the recovery of various functions related to muscle fatigue.

• The Journal of Korean Physical Therapy
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• v.13 no.3
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• pp.495-507
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• 2001

The purpose of this study was to find the effects of the dynamic lumbar stabilization exercise on functional recovery of low back pain patients. The subjects were consisted of sixty patients who had nonspecific subacute low back pain. All subjects randomly assigned to dynamic lumbar stabilization exercise group. Williams exercise group and modalities treatment group. The dynamic lumbar stabilization exercise group received modalities treatment with dynamic lumbar stabilization exercise. Williams exercise group received modalities treatment with Williams flexion exercise and modalities treatment group received modalities treatment without exercise. The Oswestry low back pain disability questionnaire was used to measure disability of low back pain. Assessment was carried out before treatment fur obtain baseline measurement of low back pain and reassessment were carried out at after 20 and 40 treatment sessions. The results of this study were as following: 1. The Oswestry low back pain disability questionnaire scores were significantly decreased after 20th and 40th treatment in dynamic lumber stabilization exercise group(p<.05). 2. The Oswestry low back pain disability questionnaire scores were significantly decreased after 20th and 40th treatment in Williams exercise group(p<.05). 3. The Oswestry low back pain disability questionnaire scores were significantly decreased after 20th and 40th treatment in modalities treatment group(<.05). 4. There were no statistical difference between the 3 groups at pre-treatment with Oswestry low back pain disability questionnaire scores(p>.05). 5. There were no statistical difference between the 3 groups after 20th treatment with Oswestry low back pain disability questionnaire scores(p>.05). 6. There were statistical difference between the 3 groups after 40th treatment with Oswestry low back pain disability questionnaire scores(p<.05). 7. The Oswestry low back pain disability questionnaire scores were significantly decreased after 40th treatment in all 3 groups and the decrement were greater in order of dynamic lumbar stabilization exercise group. Williams exercise group and modalities treatment group.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.53-56
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• 2003

The disappearance of continuous yielding and the formation of an extended region in engineering stress-strain curves at tempering temperatures of 673-873K is closely related to the reduction of mobile dislocations during tempering and dynamic recovery during tensile deformation. In addition, the occurrence of discontinuous yielding at tempering temperature above 923K would be attributed to the formation of new strain-free polygonal ferrite grain.

• The Transactions of the Korea Information Processing Society
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• v.5 no.10
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• pp.2641-2653
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• 1998