• Structural Engineering and Mechanics
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• 제46권1호
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• pp.19-37
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• 2013

The optimum design of base isolation system considering model parameter uncertainty is usually performed by using the unconditional response of structure obtained by the total probability theory, as the performance index. Though, the probabilistic approach is powerful, it cannot be applied when the maximum possible ranges of variations are known and can be only modelled as uncertain but bounded type. In such cases, the interval analysis method is a viable alternative. The present study focuses on the bounded optimization of base isolation system to mitigate the seismic vibration effect of structures characterized by bounded type system parameters. With this intention in view, the conditional stochastic response quantities are obtained in random vibration framework using the state space formulation. Subsequently, with the aid of matrix perturbation theory using first order Taylor series expansion of dynamic response function and its interval extension, the vibration control problem is transformed to appropriate deterministic optimization problems correspond to a lower bound and upper bound optimum solutions. A lead rubber bearing isolating a multi-storeyed building frame is considered for numerical study to elucidate the proposed bounded optimization procedure and the optimum performance of the isolation system.

• Journal of the Earthquake Engineering Society of Korea
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• 제3권3호
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• pp.75-86
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• 1999

An analysis model is developed to evaluate the dynamic responses of a bridge system under seismic excitations, in which pounding actions between girders are considered in addition to other phenomena such as nonlinear pier motion, rotational and translational motions of foundations. The model also considers the abutment and restrainers connecting adjacent girders to prevent the unseating failures. Using the developed model, the longitudinal dynamic behaviors of a bridge system are examined for various peak ground accelerations, and the effects of the applied restrainers are investigated. It is found that the restrainers reduce the relative displacement with the shorter clearance length as well as the higher stiffness of the restrainers for moderate excitations. However, in the region with strong excitations the restrainers may yield due to the large relative displacement. Therefore, the extension of support length in addition to restrainers may need to prevent the unseating failure more effectively.

• Journal of Agricultural Extension & Community Development
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• 제20권4호
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• pp.989-1021
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• 2013

This paper examines the activating methods of heritage tourism by focusing on ecomuseum as regional revitalization strategy of agriculture heritage. Ecomuseum can be a vital tool to actualize the purpose of agriculture and fisheries heritage system, 'dynamic conservation' of 'a living heritage'. According to case study, Byeokgolje possesses high value to preserve and local government is planning to vitalize heritage tourism, but the system of heritage tourism is not properly equipped the four requisites for it (sincerity, educational value, entertainment, and nostalgia). Byeokgolje is insufficient system as an ecomuseum and has some challenging tasks to prepare the four requisites for ecomuseum(the legacy, museum, participation and contents) despite of high possibility. It is necessary that construct the four requisites for ecomuseum and fulfil the four requisites for heritage tourism to achieve the effect of regional revitalization by link to ecomuseum. That is, authentic contents developing, the participation of local residents, shakeholder, and creative class, site construction, academic approach, and providing the method of residents' income increasing are necessary.

• Journal of the Korean Society of Physical Medicine
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• 제10권4호
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• pp.101-106
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• 2015

PURPOSE: Application of an oscillating program for the lower extremities is an effective training method for increasing muscle strength. However, no oscillatory program has yet been identified to confirm the effectiveness of oscillation for balance ability and maximum muscle strength. We investigated the effects of an 8-week vibration exercise program on the maximum muscle strength and balance of the lower extremities. METHODS: Research subjects participating in the study were 22 male and female college students with no past history of diseases of the nervous or musculoskeletal systems. All subjects were randomly divided into two groups and performed their assigned experimental treatment 3 times a week over a period of 20 min for 8 weeks. Maximum strength of the quadriceps extension, flexion, and balance ability were measured using Biodex System 4 and Biodex balance systems. RESULTS: The 8-week oscillation program resulted in a significant increase in quadriceps extension and flexion strength in both male and female participants (p<.05). The balance ability also showed a significant improvement after the oscillation program (p<.05). The balance value was higher for male 17% than for female 21% (p<.05) participants. CONCLUSION: An 8-week oscillation program led to an increase in the strength of knee flexion and extension. The balance ability also improved significantly. This positive effect on balance ability was higher in female than in male subjects.

• Environmental and Resource Economics Review
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• 제14권3호
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• pp.699-728
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• 2005

This article is basically an extension of Barten(1993), Brown et al. (1995), Holt and Bishop's(2002) price formation system. A new dynamic price formation system is attempted considering full rationality of the consumers' side. The underlying idea of the new dynamic price formation system is that consumers are rational and farsighted and thus consider past and future consumptions in addition to current consumption to accept the prices traders called. In an empirical application, the U.S. commercial fish demand data are particularly interesting to this analysis in which the species are over fished, including many of the most valuable species. Especially, the grouper-snapper complex are under management jurisdiction of the National Marine Fisheries Council. In the empirical section, it shows how to adapt the model to estimate the marginal values to consumers of commercial fisheries. Since it is conceived of regulations as inducing movements along the marginal value curves, it is of growing importance to regional and national policy makers who are confronted with competing claims on diminishing fish stocks by commercial fisheries interests. It performs well and shows the plausible signs and magnitudes of price flexibilities and interaction among species. It further contributes to the general methodology of applied economics.

• Journal of Information Processing Systems
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• 제5권4호
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• pp.207-220
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• 2009

A large number of phone calls and data services will take place in indoor environments. In Long Term Evolution (LTE), femtocell, as a home base station for indoor coverage extension and wideband data service, has recently gained significant interests from operators and consumers. Since femtocell is frequently turned on and off by a personal owner, not by a network operator, one of the key issues is that femtocell should be identified autonomously without system information to support handover from macrocell to femtocell. In this paper, we propose a dynamic reservation scheme of Physical Cell Identities (PCI) for 3GPP LTE femtocell systems. There are several reserving types, and each type reserves a different number of PCIs for femtocell. The transition among the types depends on the deployed number of femtocells, or the number of PCI confusion events. Accordingly, flexible use of PCIs can decrease PCI confusion. This reduces searching time for femtocell, and it is helpful for the quick handover from macrocell to femtocell. Simulation results show that our proposed scheme reduces average delay for identifying detected cells, and increases network capacity within equal delay constraints.

• The Journal of Korean Physical Therapy
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• 제29권1호
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• pp.39-43
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• 2017

Purpose: This study was to investigate the effects of unilateral muscle fatigue in knee and ankle joints on balance and gait in healthy adults. Methods: Exercise inducing muscle fatigue in the knee joint consisted of concentric and eccentric contraction of dominant knee extensors in healthy adults by using the Leg Extension Rehap exercise machine (HUR, Finland). Exercise inducing muscle fatigue in the ankle joint was composed of voluntary contractions and forced contractions of the dominant plantar flexors in healthy adults. Exercises to induce muscle fatigue in the knee and ankle joints were performed until the subject complained of fatigue or pain, the occurrence of muscle fatigue was confirmed by electromyography. We measured static and dynamic balance using the Good Balance system and gait performance by RS-scan. Results: Static and dynamic balance ability and spatial-temporal gait decreased significantly after muscle fatigue in knee and ankle joint. Conclusion: These results show that unilateral muscle fatigue of the lower extremities affected postural control and gait. Therefore, therapists and sport trainers should minimize the risks of fall and injuries related to unilateral muscle fatigue.

• Structural Engineering and Mechanics
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• 제16권2호
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• pp.195-217
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• 2003

This paper, which is an extension of a previous work by Viola et al. (2002), deals with the dynamic stability of beams under a triangularly distributed sub-tangential forces when the effect of an elastically restrained end is taken into account. The sub-tangential forces can be realised by a combination of axial and tangential follower forces, that are conservative and non-conservative forces, respectively. The studied beams become unstable in the form of either flutter or divergence, depending on the degree of non-conservativeness of the distributed sub-tangential forces and the stiffness of the elastically restrained end. A non-conservative parameter ${\alpha}$ is introduced to provide all possible combinations of these forces. Problems of this kind are usually, at least in the first approximation, reduced to the analysis of beams according to the Bernoulli-Euler theory if shear deformability and rotational inertia are negligible. The equation governing the system may be derived from the extended form of Hamilton's principle. The stability maps will be obtained from the eigenvalue analysis in order to define the divergence and flutter domain. The passage from divergence to flutter is associated with a noticeable lowering of the critical load. A number of particular cases can be immediately recovered.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• 제26권5호
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• pp.511-517
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• 2016

This paper presents dynamic characteristics of a new actuator using magneto-rheological(MR) fluid between two electrode type coils. The concept of the actuator is to strengthen the force due to the magnetic field produced by the electrode-coil for MR fluid. The amount and direction of current input to the electrode-coils decide the characteristics of contraction-mode and extension-mode. For achieving the required actuating displacement and actuating force, the yield stress of the MR fluid between two electrode-coils is precisely changed by the input current. In this work, the MR fluid is operated in squeeze mode. The experimental results shown in this paper depict that it can be applied in the micro-level displacement and vibration control system.

• Proceedings of the ESK Conference
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• 대한인간공학회 1995년도 추계학술대회논문집
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• pp.156-163
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• 1995

An experimental protocol was developed and tested in this study in order to quantify the motor control capability of the trunk movement for both healthy subjects and low-back pain (LBP) patients. Information processing capacity (bits/second) (Fitts, 1954) and dynamic motor perfor- mance such as flexion/extension velocity and acceleration were measured as motor control parameters under the controlled range of motion (ROM). In this study, the original experimental propocol (Kim et al., 1993, 1994) was re-designed to reduce the length of the test via a series of statistical analyses for clinical application. The accuracy of the shortened protocol was statistically examined and indicated no difference conpared to the original protocol in terms of evaluating information processing capacity. This protocol was also tested among ten healthy subjects and ten LBP patients for validation purpose. The results showed that the information processing capacity was not significantly diffenent between two groups due to the large variation although there was an apparent mean difference. Average movement time showed a significant increase in LBP patients com- pared to healthy subjects. In conclusion, it was found that the new short experimental protocol could quantify the motor control capability of neuromuscular system of the trunk and also showed the applicability to patient population.